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The Synergy of Theory and Experiment: A Symposium in Honor of Prof. John F. Stanton:
02:00pm - 05:20pm USA / Canada - Pacific - March 23, 2022 | Location: Room 25C (San Diego Convention Center)
T. Daniel Crawford, Presider; Jürgen Gauss, Organizer; Anna Krylov, Organizer; T. Daniel Crawford, Presider
Division: [PHYS] Division of Physical Chemistry
Session Type: Oral - Hybrid
Division/Committee: [PHYS] Division of Physical Chemistry

John F. Stanton, the William R. Kenan, Jr. Professor of Chemistry at the University of Florida’s Quantum Theory Project, is a role model for physical chemists: an insightful theorist who has developed some of the most important quantum chemical models who also works in close collaboration with an array of experimentalists pursuing some of the most challenging problems in molecular spectroscopy. In the spirit and recognition of Prof. Stanton’s work, this symposium will bring together theorists and experimentalists pursuing the state of the art of molecular quantum mechanics.

Wednesday
3659420 - Professor John F. Stanton: An outstanding career in science
02:00pm - 02:20pm USA / Canada - Pacific - March 23, 2022 | Location: Room 25C (San Diego Convention Center)
Henry Schaefer, Presenter
Division: [PHYS] Division of Physical Chemistry
Session Type: Oral - Hybrid
John Stanton has been a pioneer in science for morte than 30 years.
Wednesday
3654294 - Vibronic perturbation theory for Jahn-Teller and pseudo-Jahn-Teller molecules
02:20pm - 02:50pm USA / Canada - Pacific - March 23, 2022 | Location: Room 25C (San Diego Convention Center)
Bryan Changala, Presenter
Division: [PHYS] Division of Physical Chemistry
Session Type: Oral - Hybrid
Non-adiabatic effects play a central role in the spectroscopy and dynamics of open-shell and electronically excited molecules, but the vibronic coupling implicit in such systems poses both computational and conceptual challenges. Although a variety of sophisticated time- and frequency-domain techniques exist that accurately treat non-adiabatic molecules, such methods are often expensive and scale steeply with molecular size. This talk will describe some perturbative approaches to the vibronic problem, with a particular focus on the low-energy structure of Jahn-Teller and pseudo-Jahn-Teller molecules within a quasi-diabatic framework. We will discuss the minimal zeroth-order models that accurately capture the essential correlation between electronic and vibrational degrees of freedom and demonstrate that perturbative corrections based on them can provide accurate predictions even for strongly coupled systems. Some interesting phenomena not usually encountered in pure vibrational problems, such as mean-field symmetry breaking, appear along the way. We hope this approach can ultimately be developed into an efficient and accurate method for predicting spin-rovibronic spectroscopic Hamiltonians of small and medium-sized molecules.
Wednesday
3661615 - Spectral deconvolution of side chain effects in conformer population of protonated tripetides
02:50pm - 03:10pm USA / Canada - Pacific - March 23, 2022 | Location: Room 25C (San Diego Convention Center)
Division: [PHYS] Division of Physical Chemistry
Session Type: Oral - Hybrid
Conformational changes of protein and peptides, especially due to different amino acid substituents, is of interest across many fields of science. Due to the challenges of analyzing a protein’s full local environment, small peptides can be used as model systems to determine the effect of the side chain on the conformation population. To investigate how the side chain affects the intramolecular hydrogen-bonding environment and can give rise to different conformation populations, a series of tripeptides starting from Gly-Gly-Gly-H+, in which glycine monomers are systematically replaced by alanine, are explored in this contribution.
Highly resolved vibrational spectra of these species are obtained using Cryogenic Ion Vibrational Spectroscopy (CIVS). Additionally, conformer specific IR-IR double resonance techniques are used to isolate and quantify the conformational population and their changes upon amino acid substitution. Comparison with electronic structure calculations reveals the presence of three main conformational families which are differentiated by the protonation site and the hydrogen bonding around the amine group. The effect of the methyl side chain is found to mainly arise from electronic effects, modulating the proton affinities of nearby functional groups. Preferential protonation at either the carbonyl or the amine can be predicted using calculated local proton affinities. Cooperative and competing effects are also found to occur. From these model systems, information can be extrapolated to larger peptides.

Wednesday
3657061 - Assessing anharmonic effects in small hydrogen bonded systems
03:10pm - 03:30pm USA / Canada - Pacific - March 23, 2022 | Location: Room 25C (San Diego Convention Center)
Gregory Tschumper, Presenter
Division: [PHYS] Division of Physical Chemistry
Session Type: Oral - Hybrid
The honoree of this symposium has had a tremendous impact in many areas of chemistry, and his work at the interface between experimental and computational spectroscopy is just one example. This presentation will provide and overview of the systematic examination of the vibrational frequencies for a series of simple hydrogen bonded dimers with convergent ab initio quantum mechanical electronic structure techniques. Anharmonic effects are assessed with second-order vibrational perturbation theory (VPT2) for these homo- and heterogeneous dimers composed of small fragments such as H2O, HF, HCN, HCl, and H2S, but we are also in the process of extending the analysis to vibrational configuration interaction (VCI) theory in some cases. Direct comparison to experimentally measured fundamental vibrational frequencies reveals that VPT2 anharmonic frequencies computed with the CCSD(T) method and large correlation consistent basis sets appropriately augmented with diffuse functions typically differ by no more than a few wavenumbers for the intramonomer fundamental vibrations, including the challenging donor stretch. The corresponding dissociation energies that include the VPT2 anharmonic zero-point vibrational energies also tend to closely match reliable experimental D0 values. The computed results are usually accurate enough to identify and/or potentially resolve experimental discrepancies.
Wednesday
Intermission
03:30pm - 03:50pm USA / Canada - Pacific - March 23, 2022 | Location: Room 25C (San Diego Convention Center)
Division: [PHYS] Division of Physical Chemistry
Session Type: Oral - Hybrid

Wednesday
3650327 - Recent scientific adventures combining experimental and computational spectroscopy
03:50pm - 04:20pm USA / Canada - Pacific - March 23, 2022 | Location: Room 25C (San Diego Convention Center)
Timothy Zwier, Presenter
Division: [PHYS] Division of Physical Chemistry
Session Type: Oral - Hybrid
This talk will present some recent examples in which laboratory studies of molecular spectra have been synergistically combined with computational studies to bring new insights to the structure, dynamics, and excited state behavior of exotic molecules, free radicals, ions, and molecular complexes.
Wednesday
3662248 - Non-covalent interactions in multifunctional molecular complexes
04:20pm - 04:40pm USA / Canada - Pacific - March 23, 2022 | Location: Room 25C (San Diego Convention Center)
Nathanael Kidwell, Presenter
Division: [PHYS] Division of Physical Chemistry
Session Type: Oral - Hybrid
The interplay between chemical functionality and structure is a key factor in the photophysics and photochemistry of complex, flexible molecules, often giving rise to multiple potential energy surfaces. Adequate description of this relationship to understand the outcomes and properties of polyatomic molecules is made even more difficult as the number of isomers and conformations increase substantially with the size of the system. The inclusion of water-mediated interactions is often needed due to dramatic effects on the conformational preferences and photophysics. Therefore, close collaboration between experimental and theoretical methods is required to obtain a molecular-level view of such complex chemical systems. To address these opportunities, we will illustrate our fruitful, collaborative efforts to investigate the non-covalent interactions of molecular complexes using single-conformation spectroscopy and dynamics techniques to probe the photo-initiated outcomes on multiple potential energy surfaces. Thus, the photophysical, photochemical and structural details of the target conformational isomers and complexes enable multifaceted comparisons to several theoretical methods and predictions.
Wednesday
3662230 - Orbital optimized density functional theory for core-level spectroscopy
04:40pm - 05:00pm USA / Canada - Pacific - March 23, 2022 | Location: Room 25C (San Diego Convention Center)
Division: [PHYS] Division of Physical Chemistry
Session Type: Oral - Hybrid
Density functional theory (DFT) based modeling of electronic excited states is useful for investigating photophysical/photochemical properties and spectroscopic characterization of large systems. The widely used linear response time-dependent DFT (TDDFT) approach is, however, not effective at modeling many types of excited states, including (but not limited to) charge-transfer states, doubly excited states, and core-level excitations. State-specific orbital optimization (OO) can ameliorate these challenges, but has been historically underutilized due to the risk of "variational collapse" down to the ground state. We present a recently developed method for reliably converging OODFT solutions without variational collapse, for the same computational scaling as ground state DFT. We subsequently apply this method to compute core-level spectra and demonstrate excellent agreement with experiment (~0.3 eV RMS error) with the modern SCAN functional, sans any empirical shift. OODFT methods can also be used to interpret transient X-ray absorption experiments, and several such applications will be presented. Time permitting, we would also discuss inclusion of scalar relativistic effects into OODFT, which is essential for accurately modeling core electrons of heavy atoms.
Comparison of TDDFT and Restricted Open-Shell Kohn-Sham (ROKS, an OODFT protocol) for prediction of 40 excitation energies out of 1s orbitals of C,N,O and F.

Comparison of TDDFT and Restricted Open-Shell Kohn-Sham (ROKS, an OODFT protocol) for prediction of 40 excitation energies out of 1s orbitals of C,N,O and F.

O K-edge spectrum of CO<sup>+</sup> from experiment, OODFT (recoupled SCAN) and equation of motion coupled cluster (EOM-CCSD).

O K-edge spectrum of CO+ from experiment, OODFT (recoupled SCAN) and equation of motion coupled cluster (EOM-CCSD).


Wednesday
3644778 - Accuracy of VPT2/CCSD(T) IR spectral estimation for broadened signals at STP conditions
05:00pm - 05:20pm USA / Canada - Pacific - March 23, 2022 | Location: Room 25C (San Diego Convention Center)
Division: [PHYS] Division of Physical Chemistry
Session Type: Oral - Hybrid
We present the accuracy of predicting excitation frequencies and absorption cross sections of gaseous IR spectra at room temperature and pressure via VPT2. Theorists such as J. Stanton have demonstrated that CCSD(T)/VPT2 treatments to estimate excitation energies are regularly accurate to within a few wavenumbers for single-reference molecules without pathological anharmonicity under experimental conditions. However, estimation of broadened signals, intended for use in the Earth’s atmospheric temperature/pressure ranges, represents a different quantity altogether. Broadened signals reflect the superposition of Doppler/collisional effects coupled to transition dipole matrix elements for intensity. We also employ harmonic derivative-testing to identify Fermi and Dennison-Darling resonances. We compare CCSD(T)/VPT2 spectra of 10 molecules to NIST and HITRAN experimental databases. Our results benchmark the statistical error distributions of excitation frequencies and absorption cross sections. We similarly examine the statistical error distributions of using CCSD(T) diagonal couplings with MBPT(2) off-diagonal couplings as a reduced-cost scheme, as well as MBPT(2) for all vibrational couplings. All errors were found to be normally distributed.
Incorporating Polymer Science into the Classroom:
02:00pm - 06:00pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 14 (Marriott Marquis San Diego Marina)
Heather Broadhead, Organizer, Presider; Philip Costanzo, Organizer, Presider; Dominik Konkolewicz, Organizer; Sarah Morgan, Organizer, Presider
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - In-person
Division/Committee: [POLY] Division of Polymer Chemistry
Wednesday
3654217 - Seeing the flexibility of polymers
02:00pm - 02:15pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 14 (Marriott Marquis San Diego Marina)
Jamie Sorrell, Presenter
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - In-person


Polymers are a key component in today’s society. Part of what makes polymers so prevalent is their durability. This is partially due to their viscoelastic nature, which imparts both solid and liquid-like behavior. Overall, this can lead to differences in polymer performance based on the testing rate. To impart a better understanding of how applied forces can determine how polymers behave, we designed a lesson plan for tenth-grade students revolving around stretching speed of slime. First, students will be engaged by stretching puddy. Students will observe that gum breaks when it is stretching quickly, but can reach extreme elongation if stretched slowly. Second, students will then explore how to collect data to determine the stretching rate of the gum; they will stretch their gum for one hundred centimeters while videoing and timing the stretch in ten centimeters increments. Finally, after discussing how to compile their collected data on a distance vs. time graph, students will create a standard stretchy slime sample and conduct a rate test on the slime. Students will manipulate the standard sample recipe to try to improve the rate of the stretchy slime. Finally, the findings will be assessed, and the results presented in a poster session. This activity is a great way for students to manipulate and test the qualities of polymers in a high school setting.

Wednesday
3652861 - Polymer science and engineering curriculum and laboratory activities developed for high school classrooms by RET participants at the University of Southern Mississippi
02:15pm - 02:30pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 14 (Marriott Marquis San Diego Marina)
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - In-person
Teachers participating in the National Science Foundation Research Experience for Teachers (RET) Site for Sustainable Polymer Engineering Research at the University of Southern Mississippi engage in six-weeks of summer research with faculty in the School of Polymer Science and Engineering. Teachers engage in project themes that include (1) Reducing waste through design of degradable and bio-based polymers, (2) Improving water quality through polymer sensors and delivery vehicles, (3) Enabling alternative energy approaches with high performance polymers. RET participants work with faculty and graduate students to develop research-based laboratory activities for implementation in their classrooms that incorporate real-world polymer examples while addressing national science standards. RET Participants also mentor Middle School Science Teacher Workshop participants to assist in the development of polymer science and engineering curriculum for middle school students. Throughout the year, RET faculty and graduate student mentors visit RET participant’s classrooms to assist in facilitating the research-based lesson and to lead hands-on laboratory activities. An overview of the successful summer research program will be highlighted, with examples of engaging activities that explore fundamental science and engineering concepts. Successful tools used to develop lessons and improve the impact of polymer research in the classroom will be presented.
2021 RET Participants

2021 RET Participants


Wednesday
3657458 - Research experience for teachers: Bringing polymer science into the high school classroom
02:30pm - 02:45pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 14 (Marriott Marquis San Diego Marina)
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - In-person
As part of the Research Experience for Teachers (RET) program at the University of Southern Mississippi's School of Polymer Science and Engeering, a lesson plan was created through which students learn the science of tensile testing as well as how to be better stewarts of the environment. Thorugh this lesson, students learned the role that polymers play in their everyday lives, while becoming aware of the growing marine microplastics problem. Students took a pretest to assess their prior knowldege of the products made from polymers, such as desks, pencils and even clothing. The teacher assessed the student's prior knowledge of the growing marine microplastics problem and the efects it has on marine life. Through independent research and teacher-led discussion, videos and interviews, students discovered how fishing lines contribute to the growing marine microplastics problem. Students were given materials to assemble redfish rigs using four commonly available polymers (Nylon, PE, PVDF and PP). Students form a hypothesis on which polymer they think has the highest tensile strength, and therefore has the least chance of fouling. The students were grouped, with four students per group, and the students constructed crude tensile testing apparatuses to test the tensile strength of the fishing lines. The students used these apparatuses to test the redfish rig made from each polymer, with four total tensile testing stations and each testing station set up to test a different polymer. The groups gathered data, created graphs, reported that data to classmates, as well as compared data across the class. The students, then made four more redfish rigs using what they learned through the first trial of tensile testing. Ultimately, the students learned about the growing microplastics problem and how they can be better environmental stewards.

Wednesday
3657517 - Rational designing of one-dimensional photonic crystal
02:45pm - 03:00pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 14 (Marriott Marquis San Diego Marina)
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - In-person
Understanding and controlling light-matter interactions is of central interest for various applications such as communication, renewable energy, and sensing technologies. Photonic crystals (PCs) are a class of materials that can manipulate propagation of electromagnetic waves to on-demand display different color, using at least two materials with distinct refractive indices. Briefly, the mechanism of reflection of light in 1-D photonic crystal is driven by following parameters: (1) layer thickness dictates the wavelength of the reflected light according to Bragg’s equation and (2) the difference between the refractive indices dictates the intensity of the reflected light. The goal of this RET project was to develop two suitable polymers (polystyrene and phenolic resin) and to design their appropriate thicknesses to fabricate a stack of bi-layer films for preparing a photonic crystal that would reflect light in a targeted wavelength range (visible, ~400-700 nm) with desired intensity. Specifically, the layer thickness can be controlled by varying the polymer solution concentrations for spin coating. Additionally, we identified a step of surface treatment is necessary for improving the wettability between distinct polymer layers. Through this project, we successfully developed a lesson for chemistry course that may be used for high school and junior-college students.[ZQ1] This lesson addresses the 5 Es of learning at this level (engage, explore, explain, elaborate and evaluate) where students demonstrate an understanding of the nature of properties of various types of chemical solutions, develop and use models to explain the dissolving process in solvents at the molecular level by spin-coating paints on various surfaces.

Wednesday
3640994 - Zooming in on polymer chemistry and designing a polymer synthesis experiment for virtual undergraduate laboratory
03:00pm - 03:25pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 14 (Marriott Marquis San Diego Marina)
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - In-person
Teaching polymer chemistry principles early in the undergraduate curriculum allows students to find connections between chemistry and real-world applications and can promote interest in science and scientific research. Performing laboratory experiments on polymers is of equal importance when integrating polymer concepts into undergraduate-level lectures. There are several lab demonstrations on polymer science in synthesis, characterization, and applications, yet more, easy-to-handle experiments are needed that connect polymers to organic reactions, spectroscopy, and sustainability, especially in a virtual setting. We designed a virtual experiment to incorporate the synthesis of high sulfur-content polymers into the general chemistry laboratory during the pandemic (Figure 1). Teaching assistants (TAs) performed the experiments and collected the necessary data and observations for students. Video recordings of the polymerization reactions, reaction times, and collages of digital images depicting reaction progress (viscosity and color changes) are provided to students. During a single 3-hour long virtual lab meeting, students watch the lab videos, read the student handout and a research paper, and discuss the results and observations with their peers and lab TAs. The lab experiment demonstrates the interdependence of general chemistry learning objectives including chemical bonding, radicals, reaction kinetics, thermodynamics, stoichiometric calculations, and spectroscopy. In addition, this virtual experiment introduces undergraduate students to polymer chemistry, encourages them to look beyond the textbooks and lecture resources by using literature articles, and connects general chemistry concepts with upper-level chemistry classes. Post-lab survey results show that students find the video recordings and group discussions on the polymerization reactions very helpful in understanding a new concept within a virtual distant-learning environment.
<b>Figure 1.</b> Polymer synthesis design for virtual undergraduate lab

Figure 1. Polymer synthesis design for virtual undergraduate lab


Wednesday
3649480 - From dairy waste to sustainable hydrogels: An advanced polymer teaching lab experiment
03:25pm - 03:50pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 14 (Marriott Marquis San Diego Marina)
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - In-person
Showcasing current innovations in sustainable polymers presents an opportunity to apply green chemistry concepts. Furthermore, students are exposed to the importance of a circular economy and the United Nations Sustainable Goal of responsible production and consumption. Herein, we present a teaching lab experiment highlighting several green chemistry principles including the usage of renewable feedstocks, high atom economy, energy efficient synthesis, waste prevention, and using water as a benign solvent. This experiment creates a biobased hydrogel derived from either lactose or sucrose, natural disaccharides which can be sourced from dairy waste or sugarcane feedstocks. The carbohydrate monomers are appended with photoreactive methyl methacrylate groups that are crosslinked to generate a hydrogel with tunable physical properties by varying the crosslinking density. Structure-property relationships are assessed through comparative studies that involve performing compression tests to measure the modulus of elasticity, and water uptake analysis at different pH. Using two different disaccharide monomers adds an inquiry-based approach to the experiment. Additionally, the comparison of the disaccharide methacrylate hydrogels to commercially available products highlight the importance of evaluating competitive properties. Classroom implementations at the University of Minnesota and Augsburg University will be shared including student results, learning outcomes, and critique of the experiment.
Examples of student prepared sugar methacrylate hydrogels

Examples of student prepared sugar methacrylate hydrogels


Wednesday
Intermission
03:50pm - 04:20pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 14 (Marriott Marquis San Diego Marina)
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - In-person

Wednesday
3657388 - Teaching polymer synthesis using the CREATE method
04:20pm - 04:45pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 14 (Marriott Marquis San Diego Marina)
Frank Leibfarth, Presenter
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - In-person
The CREATE (Consider, Read, Elucidate the hypothesis, Analyze and interpret and data, and Think of the next Experiment) method of teaching enhances student critical thinking skills while teaching fundamental aspects of polymer synthesis through an intensive analysis of primary literature. This CREATE approach requires students to read and analyze a set of foundational papers published on Polymer Synthesis. Content knowledge is acquired as an underlying principle to understand why and how the study was conducted, what hypotheses were presented, and how each piece of data contributes to the manuscript. Through the CREATE method, students complete pre-class assignments, and the in-class portion of the curriculum is focused on small group guided discussions that use diverse pedagogical tools to encourage critical thinking and contextualizing the work, such as concept mapping, experimental design, and data visualization. These diverse tools naturally provide a dynamic learning environment that encourages student engagement and provides a variety of content delivery mechanisms for students with different learning styles. In this lecture, I will present how I have used the CREATE method to teach an undergraduate/graduate level Polymer Synthesis course.

Wednesday
3662526 - Critically appraised topic (CAT) pedagogy to conduct virtual undergraduate polymer research
04:45pm - 05:10pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 14 (Marriott Marquis San Diego Marina)
Dr. Michelle Gaines, Presenter
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - In-person
The COVID pandemic introduced new challenges for experimentalists to progress research goals outside of the traditional lab environment. Thus, the pandemic required me to develop a meaningful virtual framework for students to achieve course credit for undergraduate research. To achieve these goals, I implemented the Critically Appraised Topic (CAT) technique to answer a relevant research question from the information presented in relevant articles collected from the literature. CAT is an evidence-based practice, developed medical practitioners to help synthesize the massive volume of peer-reviewed information in medical and scientific journals. The technique involves obtaining a standardized summary of research evidence organized around a clinical question. Ultimately, CAT provides a detailed critique of the research on a topic, summarized into a clinical relevance statement. Although CAT is most often used to synthesize technical medical information, I used the technique in my polymer chemistry research lab to teach students how to conduct a detailed review of the chemical scientific literature and thus conduct qualitative research. The steps involved with employing the CAT are to: 1) Ask, 2) Search, 3) Appraise, 4) Apply, & 5) Evaluate. In summary, each student developed a research question such as “What is the consensus on the existing research on 3D-cell culture made from hydrogels?” Once formulated, the students conducted a systematic search of the literature in PubMed and SciFinder, by incorporating specific search terms and evaluating the relevance of each queried result. They summarized the key findings from a subset of relevant research articles (4-6 articles) and identified the themes that coincided with answering their research question. Each student reported their findings in the form of a written report and technical oral presentation, and several of them presented their findings to the Spelman community during our annual Spelman Research Day.
Summary of Key Findings from CAT conducted on the research question: “What is the consensus on the existing research on 3D-cell culture made from microgels?”

Summary of Key Findings from CAT conducted on the research question: “What is the consensus on the existing research on 3D-cell culture made from microgels?”


Wednesday
3662262 - Development and assessment of guided inquiry activities for polymer science
05:10pm - 05:35pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 14 (Marriott Marquis San Diego Marina)
Jennifer Laaser, Presenter
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - In-person
Guided inquiry learning is a powerful framework for active learning in STEM classrooms. To enable instructors to employ guided inquiry techniques in college-level polymer science classrooms, we have developed a collection of 19 guided inquiry activities designed to help students explore core topics in polymer chemistry, polymer physics, and polymer characterization. The activity collection, which is freely available and under ongoing development, has been used successfully as the primary instructional material for an undergraduate course in synthesis and characterization of polymers at the University of Pittsburgh over the past three years. Initial pre/post assessments in this course suggest that the guided inquiry approach improves students' confidence in figuring out how to solve unfamiliar problems and in reaching conclusions from given data or evidence even in upper-level chemistry electives. Implementation and evaluation of the activities at other universities will be a critical next step for refining the collection to serve as a useful resource across a wide range of educational contexts.
Excerpt from a guided inquiry activity on molecular weight and dispersity included in the described collection.

Excerpt from a guided inquiry activity on molecular weight and dispersity included in the described collection.


Wednesday
3656670 - Polymer bonds to green and sustainable chemistry
05:35pm - 06:00pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 14 (Marriott Marquis San Diego Marina)
Jane Wissinger, Presenter
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - In-person
An upper division green chemistry lecture course provides an excellent opportunity to illustrate how chemistry and chemical engineering majors can connect their science knowledge to society and sustainable innovations in future careers. As one of many topics covered, polymers and plastics resonates strongly with students as a challenge to scientists to maximize the benefits polymers bring to human quality of life while minimizing their negative effect on health and the environment. The detrimental impact of plastics on marine life particularly accentuates the unintended consequences of the ubiquitous use of polymers in commercial products, and necessitates the need for creative scientists willing to address these challenges.

In the polymers module, students are tasked with applying the fundamental skills of functional groups, bonding, and reactivity to solidify their knowledge of polymer structures/representations, syntheses, and (un)reactivity. Statistics showing the massive growth of the polymer industry illustrate material scientists’ mastery in design for functionality using a reductionist approach, but failure to foresee the pollution that would result. Students read current literature articles demonstrating modern approaches to sustainable polymers using a systems thinking approach and targeting a circular economy. Classroom discussions center on examples, many from the University of Minnesota’s Center for Sustainable Polymers (CSP), where advances in use of renewable monomers, greener processes, and design for recyclability, degradability, and composting are accomplished through innovative chemistries. CSP graduate students or postdocs are often guest speakers and provided with the professional development opportunity to share their research.

Students research their own polymer topic of choice and complete an assignment that spans the molecular structure to broader society contributions that can be realized. Connecting these advances in polymeric materials to attaining the United Nations 17 Sustainable Development Goals highlights the essential role scientist will play in a sustainable future.

General Papers/New Concepts in Polymeric Materials:
02:00pm - 06:00pm USA / Canada - Pacific - March 23, 2022 | Location: Marriott Grand Ballroom: Section 2 (Marriott Marquis San Diego Marina)
Daniel Savin, Organizer; Mahsa Haseli, Presider
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - In-person
Division/Committee: [PMSE] Division of Polymeric Materials Science and Engineering
Wednesday
3643702 - Non-fluorinated diatomaceous earth based hydrophobic sponge for oil/water separation
02:00pm - 02:20pm USA / Canada - Pacific - March 23, 2022 | Location: Marriott Grand Ballroom: Section 2 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - In-person
Applications of natural diatomaceous earth (DE) particles in industrial applications have taken great attention in the last few years as an alternative to the synthetic siliceous micro-nano particles, due to high porosity, low cost, and eco-friendliness. DE particles are a good substitute for synthetic silica due to their higher siliceous content (more than 80%). The properties of the organic waste adsorbent depend on the superhydrophobicity of the surface and as well as higher open cell structure of the polymer adsorbent. Surface modified superhydrophobic/hydrophobic DE particles will enhance the surface properties of polyurethane (PU) polymer form. During this study, raw DE undergoing non-fluorosilane surface modification with the help of octadecyltrichlorosilane. Modified DE’s are going to be characterized using scanning electron microscope (SEM), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR) and contact angle to understand the properties of the modified DE particles. Superhydrophobic DE particles will be firmly attached to PU form to create a higher open cell structure superhydrophobic/hydrophobic PU form. Resulting superhydrophobic/hydrophobic DE-PU form able to show higher adsorption capacity on oil present in the wastewater systems.

Wednesday
3647162 - Determination of chemical warfare agent distilled mustard, HD, mass uptake trends in polyurethane and polysiloxane-based polymers and associated composites using liquid and vapor chemical exposure conditions
02:20pm - 02:40pm USA / Canada - Pacific - March 23, 2022 | Location: Marriott Grand Ballroom: Section 2 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - In-person
This work focuses on determining physicochemical interactions that influence the resistance of materials to chemical contamination, specifically for the case of chemical warfare agent exposure to polymers used as binders in composite materials like coatings. Experimental work has been performed to study the differences in chemical mass uptake for HD (bis(2-chloroethyl) sulfide, distilled mustard) by polyurethane- and polysiloxane-based thin films and associated high solids-loaded coatings, including the use of probe non-agent molecules to interrogate specific penetrant-polymer interactions. Retention of chemical warfare agent mass is assessed by chromatographic analysis of extraction solutions generated by post-exposure immersion of materials in contaminant-specific solvents. By changing the means of exposure to materials, whether direct deposition of a neat liquid droplet to the material surface or exposure to vapor emanating from a proximal droplet in a closed volume, relative differences in the contributions of different routes of retention (e.g., molecular diffusion, liquid phase surface adhesion) can be surmised. This is particularly important for the case of screening steps for formulation of engineered coatings materials for which there are many constituents, each of which may individually or cooperatively affect the overall chemical resistance of the coating material. Details will be presented that cover estimations of the time-varying vapor concentration that leads to an integrated total dose or exposure and how this compares to the exposure condition associated with the liquid phase deposition of discrete agent droplets. The understanding garnered from considering chemical retention not only informs next generation decontamination approaches but also coatings formulations that are tuned for chemical resistance, reduced decontamination burden, and mitigated hazard for Warfighter personnel. [Approved for Public Release: Distribution Unlimited]
Wednesday
3647180 - Acid-doped biopolymer nanocoatings for flame retardant polyurethane foam
02:40pm - 03:00pm USA / Canada - Pacific - March 23, 2022 | Location: Marriott Grand Ballroom: Section 2 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - In-person
Soft furnishing fires contribute to 29% of fire causalities and $5.7 billion in direct property damage annually. Polyurethane foam, a common component in soft furnishings known for its comfort and flexibility, poses a risk of exposure to toxic gases and propagation due to melt dripping when ignited. Various acid salts were added to a layer-by-layer assembled nanocoating, consisting of chitosan (CH) and carboxymethyl cellulose (CMC), to improve flame retardancy and understand the salt influence on the flammability of polyurethane foam. The phosphoric acid doped coating exhibits self-extinguishing behavior, with reduced peak heat release rates (pkHRR) and reduced foam damage. By depositing this environmentally-benign coating on polyurethane foam, the inherent danger of soft furnishing fires can be significantly reduced and in a non-toxic manner.
Wednesday
3648557 - Effect of heparin/collagen layer-by-layer coating in immunomodulatory functions of mesenchymal stromal/stem cells stimulated by IFN-γ
03:00pm - 03:20pm USA / Canada - Pacific - March 23, 2022 | Location: Marriott Grand Ballroom: Section 2 (Marriott Marquis San Diego Marina)
Mahsa Haseli, Presenter
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - In-person
Human mesenchymal stromal cells (hMSCs) are multipotent cells that have been proposed for cell therapies due to their immunosuppressive capacity that can be enhanced in the presence of interferon gamma (IFNγ). In this study, multilayers of heparin (HEP) and collagen (COL) (HEP/COL) were used as a bioactive surface to enhance the immunomodulatory activity of hMSCs using soluble IFNγ. Multilayers were formed, via layer-by-layer assembly, varying the final layer between COL and HEP and supplemented with IFNγ in the culture medium. This study evaluates the viability, adhesion, real-time growth, differentiation, and immunomodulatory activity of hMSCs on HEP/COL surfaces. HMSCs viability, adhesion, and growth were superior when cultured on HEP/COL surfaces compared to tissue culture plastic. The possibility of inducing hMSCs to differentiate into osteoblasts and adipocytes was measured by exposing them to differentiation medium specific to each lineage after IFNγ treatment. This study confirms that hMSC osteogenic and adipogenic differentiation remained unaffected when cultured in HEP/COL multilayers. This study measures the level of indoleamine 2,3-dioxygenase (IDO) secretion to evaluate the hMSCs immunomodulatory factor expression. IDO expression was higher on HEP/COL surfaces treated with IFNγ. This study investigates the suppression of T-cell proliferation in peripheral blood mononuclear cells (PBMC) when co-cultured with hMSCs on HEP/COL multilayers with IFNγ. hMSCs cultured in HEP/COL surfaces in the presence of soluble IFNγ have a greater capacity to suppress T-cell proliferation from CD3/CD28-activated peripheral blood mononuclear cells. Altogether, (HEP/COL) multilayers with IFNγ in culture medium provides a potent means of enhancing and sustaining immunomodulatory activity to control hMSCs immunomodulation leading to a potential improvement in the efficacy of hMSCs-based therapies aimed at treating inflammatory and immune diseases.
Wednesday
3648852 - Mussel-inspired polymeric coatings with single/dual/multiple antimicrobial and antifouling functions
03:20pm - 03:40pm USA / Canada - Pacific - March 23, 2022 | Location: Marriott Grand Ballroom: Section 2 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - In-person
Development of smart switchable surfaces to solve the inevitable bacteria attachment and colonization have attracted plenty of attentions, however, it proves very challenging to achieve on-demand regeneration for non-contaminated surfaces. We develop a series of stimuli-responsive antibacterial surfaces via host-guest interaction assembly, catechol structural adhesion, as well as electrostatic interaction, topologically combining stimuli-responsive polymers upon target surfaces. From the point view of structural design, the peculiar hydration layer generated by hydrophilic segments severs the route of initial bacterial attachment and subsequent proliferation, while the synergistic effect on chain conformation transformation and peculiar antimicrobial groups greatly promotes the on-demand bacterial release in response to the external factors switch. These resultant surfaces exhibit triple successive antimicrobial functions simultaneously: (i) resist ~85% of initial bacterial attachment, (ii) kill ~90% of inevitable bacteria attack, and (iii) release over 95% of killed bacteria even after several cycles. These results not only present potential and promising strategies to develop renewable antibacterial surfaces with successive antimicrobial functions, but also contribute several new antimicrobial platforms for biomedical or surgical applications.

Wednesday
Intermission
03:40pm - 04:00pm USA / Canada - Pacific - March 23, 2022 | Location: Marriott Grand Ballroom: Section 2 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - In-person

Wednesday
3648944 - Withdrawn
04:00pm - 04:20pm USA / Canada - Pacific - March 23, 2022 | Location: Marriott Grand Ballroom: Section 2 (Marriott Marquis San Diego Marina)
Session Type: Oral - In-person

Wednesday
3649552 - Encoding pressure sensitive adhesion in brush architecture
04:20pm - 04:40pm USA / Canada - Pacific - March 23, 2022 | Location: Marriott Grand Ballroom: Section 2 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - In-person
Pressure sensitive adhesives (PSAs) are typically manufactured through exploratory mixing of polymers with various additives such as tackifiers and plasticizers to meet application specific requirements defined by tack stress, work of adhesion, bulk stiffness, and cohesive strength. These composite materials are difficult to fine-tune without changing chemical composition, which compounds the risk of low molecular weight compound leachability and property drift. Development of brush-like PSAs with precisely controlled network architecture overcomes these pitfalls by establishing viscoelastic control in one homogenous additive-free material. Herein, an adhesion-by-architecture approach to PSA engineering is examined. Polyisobutylene was utilized as a model brush-like elastomer system showing architecturally programmable adhesion behaviors empowered by the independent control over relaxation times and equilibrium modulus. Studies suggest this approach translates to a variety of chemistries including acrylate systems. This approach is advanced to the brush graft-copolymer platform demonstrating a combination of high tack and high cohesive strength. The graft copolymer bottlebrush architecture enhances the viscoelastic control to six independent architectural variables while physical crosslinks permit hot-melt preparation and molding. Furthermore, we establish direct structure property correlations between brush polymer architectures, viscoelasticity, and adhesion to cover a variety of PSA applications.

Wednesday
3652137 - Interfacial protein assembly as a chemical-free strategy towards surface functionalization
04:40pm - 05:00pm USA / Canada - Pacific - March 23, 2022 | Location: Marriott Grand Ballroom: Section 2 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - In-person
For many materials and devices, the physicochemical properties and functionalities of their surfaces are vitally important for their performance. Traditional methods for surface modification utilize covalent strategies, such as grafting "from/to", or non-covalent strategies, such as layer-by-layer deposition. However, these methods suffer from critical drawbacks, such as low grafting density, non-biocompatibility, or the requirement for specific surface chemistries and geometries. In this talk, we present our work on leveraging the self-assembly of silk fibroins, a class of network-forming structural proteins, at solid-liquid interfaces as a versatile "chemical-free" approach towards functionalizing surfaces. Our studies have shown that in conditions which balance protein-protein and protein-surface interactions, interfacial silk fibroin self-assembly can yield adherent, defect-free coatings on a wide range of organic and inorganic substrates. These coatings transform the physicochemical properties of surfaces and endow new functionality without requiring covalent chemistry, adhesion motifs, specific substrate geometries, or surface pre-activation. Due to the amphiphilicity of silk fibroins, our coating strategy tolerates both hydrophobic and hydrophilic surfaces, including PTFE, PDMS, TiO2, stainless steel, and other common materials. The properties and morphologies of self-assembled coatings depend on the silk fibroin sequence. For example, coatings assembled from Bombyx mori silk fibroin improve cell adhesion and neurite extension, while coatings assembled from recombinant spidroin inhibit cellular attachment. Furthermore, we have recently found that macromolecular "payloads" can be incorporated into coatings via interfacial co-assembly with silk fibroin. Thus, whereas fouling of surfaces by proteins has long been considered an undesirable but unavoidable problem, our research utilizes this robust phenomenon the basis of a modular and versatile bottom-up approach for creating multifunctional surfaces.
Wednesday
3652376 - Wetting transparency of ultrathin polymer films
05:00pm - 05:20pm USA / Canada - Pacific - March 23, 2022 | Location: Marriott Grand Ballroom: Section 2 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - In-person
The wetting behavior of ultrathin polymer coatings (< 100 nm) has been reported to deviate from bulk as thicknesses approach intermolecular interaction length scales, where surface wetting becomes influenced by underlying substrates. Such unique wetting properties have been extensively investigated for 2D materials such as graphene as a “wetting transparency” phenomenon, and study into polymer wetting is essential to advance emerging nanocoatings such as atomic/chemical vapor deposition. However, the fundamental wetting mechanism in ultrathin polymer films is not well understood due to a lack of systematic study of homogeneous layers. In this study, we aim to decouple surface energy contributions to wetting behavior from long-range van der Waals (vdW) forces and short-range hydrogen bonding interactions utilizing a model cross-linked bilayer system of well-studied polymers: poly(methyl methacrylate) (PMMA) and polystyrene (PS). We hypothesize that the critical thickness of wetting transparency for polymer coatings is larger than that for 2D materials because polymeric materials are more corporative, i.e., vdW forces propagate longer distances than in graphene. Using equilibrium contact angle as a measure of surface energy, we calculated contact angle dependence on polymer film thickness based on vdW potentials from Lifshitz theory to estimate Hamaker constants that characterize molecular-molecular interactions. We observed that experimental contact angles deviated from their bulk values at film thicknesses around ~10 nm, longer than predicted values (~2 nm). Moreover, the ability for the model system to hydrogen bond manifested as a dominating force in surface energy and wetting, suggesting interruption of vdW potential contributions. This initial finding supports our hypothesis that vdW forces may influence longer distances for wetting transparency than the vdW potential predicts. This presentation will discuss surface energy contributions from short- and long-range molecular interactions from experimental contact angle measurements and compare them to theoretical predictions previously established to gain further insight on enthalpic contributions from the bilayer polymer surface and provide critical information on wetting of ultrathin coatings.

Wednesday
3655647 - Initial bacterial retention on polydimethylsiloxane of various stiffnesses; the relevance of modulus (mis)match
05:20pm - 05:40pm USA / Canada - Pacific - March 23, 2022 | Location: Marriott Grand Ballroom: Section 2 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - In-person
Controlling the colonization of materials by microorganisms is crucial in a wide range of industrial and clinical settings. Owing to continuous advances in polymer chemistry, polymer-based devices have become increasingly used to reduce chronic infection and medical device failure. However, the underlying mechanisms that govern the interactions of bacteria with material surfaces remain poorly understood.The material properties, which alter bacterial attachment, are intricately entangled and include chemistry, hydration, surface charges, topography and mechanical properties. In order to shed further light on the complex issue of cell-substrate adhesion and the impact on it by surface elasticity, we investigated the initial bacterial retention of Escherichia Coli on model poly(dimethysiloxane) (PDMS) surfaces.
Our reference PDMS system was designed such that out of the three parameters, that determine bacterial retention (chemical composition, stiffness and surface topography), only one was systematically varied, i.e. the mechanical stiffness. Initial bacterial retention could thus be monitored depending on a single parameter, i.e. materials Young’s modulus. Substrates were engineered such that the surface modulus values, as measured by atomic force microscopy, ranged between 2 and 9 MPa. This was achieved by varying the crosslinking density of PDMS. Following crosslinking, we performed Soxhlet extraction to investigate the effect of non-crosslinked, free chains. The number of bacteria retained, as assessed by initial retention studies, decreases with the increase of both the bulk and surface mechanical stiffness values down to a value corresponding to the Young’s modulus of the bacterial cell. For higher values than this threshold, the number of adherent bacteria remains constant. We tentatively explain this observation by considering conformal overlay of bacterial and material surfaces, which might be addressed by considering elastocapillary effects and contact mechanics between bacteria and a soft elastomer surface.
The number of colonies forming units as a function of a) the bulk Young’s modulus and b) the nanoscale Young’s modulus

The number of colonies forming units as a function of a) the bulk Young’s modulus and b) the nanoscale Young’s modulus


Wednesday
3655941 - Withdrawn
05:40pm - 06:00pm USA / Canada - Pacific - March 23, 2022 | Location: Marriott Grand Ballroom: Section 2 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - In-person

General Papers/New Concepts in Polymeric Materials:
02:00pm - 06:00pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 25 (Marriott Marquis San Diego Marina)
Daniel Savin, Organizer, Presider
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
Division/Committee: [PMSE] Division of Polymeric Materials Science and Engineering
Wednesday
3659627 - Effect of precise and non-precise linker length, backbone polarity, and dispersity on thermal and rheological properties of dynamic ethylene networks
02:00pm - 02:20pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 25 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
The precise placement of ionic and non-ionic side groups has been shown to have a strong impact on the crystallization of polyolefins and polyacetals, resulting in unique temperature dependent crystal phases and enhanced proton conduction. A series of dynamic ethylene networks were synthesized to study the effect of precise and non-precise linker length, backbone polarity, and dispersity on the thermal and rheological properties of these networks. Oscillatory shear rheology was performed over a 100 degree temperature window to measure the rubbery plateau modulus and the terminal relaxation behavior. Glass transition temperature and crystallization studies were performed using differential scanning calorimetry. Precise vs non-precise linkers show negligible impact on the rubbery plateau modulus and have a similar glass transition temperature, but the induction period for crystallization in the non-precise networks is longer than the precise network. This builds upon our previous work on the evolution of melting temperatures in dynamic ethylene networks. A comparison of the glass transition temperature (Tg) normalized relaxation times of dynamic ethylene oxide vs dynamic ethylene networks suggests that for the same precise linker length the backbone polarity doesn’t influence relaxation behavior. The effect of odd vs even linker length in polymer networks is another example of the impact of precise chemistry on properties such as the glass transition and melting transition temperatures. In contrast to previous works on permanent networks, the odd even effect is not observed in the dynamic ethylene networks.
Wednesday
3661024 - Unexpected direct synthesis of benzil-linked polymers for electrochemical energy storage via the benzoin reaction
02:20pm - 02:40pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 25 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
ABSTRACT: New strategies for the sustainable synthesis of redox-active organic polymers could lead to next-generation organic electrode materials for electrochemical energy storage and electrocatalysis. Among redox-active moieties, benzils or aromatic 1,2-diones are particularly attractive due to their potentially high gravimetric capacities and fast charge/discharge rates. Herein, we demonstrate that the cyanide-catalyzed polymerization of aldehydes via the benzoin reaction unexpectedly leads directly to insoluble redox-active 1,2-dione-linked polymers instead of the expected benzoin-linked materials, as confirmed by solid-state nuclear magnetic resonance spectroscopy and electrochemical characterization. In particular, the thiophene-based polymer CORN-BP-2 (CORN = Cornell University) is a promising organic electrode material due to its high gravimetric charge storage capacity (106 mAh/g), exceptional rate capabilities (64% capacity retention when the discharge rate is increased from 0.1 to 10 A/g), and excellent long-term cycling stability. As such, the tandem benzoin-oxidation reaction reported here represents a promising new strategy for the sustainable synthesis of redox-active organic materials.
Wednesday
3662224 - Designing a new lattice model to simulate low-molecular-weight block copolymers for nanolithographic applications
02:40pm - 03:00pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 25 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
A new lattice model is designed to be suitable for simulating low-molecular-weight block copolymer (BCP) melts currently used in experiments to achieve sub-10nm domain sizes (i.e., having an invariant degree of polymerization between 102 and 103). It gives an isothermal compressibility comparable to real polymers such as poly(styrene) and poly(methyl methacrylate), high Monte Carlo simulation efficiency, and the fluctuation effects important for the low-molecular-weight BCPs. With its high lattice coordination number, the model can also be readily used for branched chains such as star BCPs. When the Shaffer’s method of preventing bond-crossing (J. Chem. Phys. 1994, 101, 4205) is implemented, it can further be used to study simultaneously the static and dynamic properties of low-molecular-weight BCPs needed for nanolithography.
Wednesday
3660060 - Icephobic coatings with exceptional mechanical durability
03:00pm - 03:20pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 25 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
Icing of surfaces is an omnipresent phenomenon in the winter that can adversely impact a wide spectrum of systems including transportation systems (aircrafts, drones, trains, etc.), infrastructures, and energy systems. A range of surfaces including slippery, liquid infused, low interfacial toughness and stress-localized surfaces have been developed to minimize ice adhesion on surfaces. However, low durability of these surfaces under various mechanical, chemical, and environmental stimuli and especially rain erosion has limited their applicability to real applications. Although stress localized surfaces have shown to be a promising method to implement icephobicity and long-term durability simultaneously, but they fail in harsh condition of rain-erosion
Here, we present a new material paradigm to develop highly durable ice-shedding surfaces that passes the rain erosion test at a speed of 172 m/s done by a third party. In this paradigm, we boosted mechanical properties such as weathering , scratch resistance, and strength of the coating without affecting icephobic performance. Such passive coatings with exceptional mechanical properties are so promising for high performance applications such as aerospace industry and wind turbines with low maintenance cost and long-lasting performance.

Wednesday
3660855 - Hydrophobic polymers with various ion exchange capacities for direct air capture of carbon dioxide
03:20pm - 03:40pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 25 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
The rise in emission of greenhouse gases has brought up many concerns worldwide. Since emission reductions alone cannot be a solution to climate change, negative emission technologies are needed. Direct air capture (DAC) is one such technology that can capture CO2 directly from ambient air and reduce the CO2 concentration in the atmosphere. To achieve that, sorbents with high capturing capacity and low cost, and fast kinetics are required. The current study investigates a series of amine-based polymers with hydrophobic characteristics that utilize moisture-driven CO2 capture and release. We synthesized series of acrylate-based networks that contained a variable amount of ammonium and trifluoromethane groups to tailor the ion exchange capacity and hydrophobicity. These sorbents absorb CO2 when exposed to ambient air and release it when in contact with an aqueous solution. To further investigate the capturing capacity of the hydrophobic sorbents, they were cryomilled into powders. The powdered sorbents were then tested in moisture-swing set up for different cycle times. The capturing capacity and kinetics of the solid and powdered form factors were investigated.
Wednesday
Intermission
03:40pm - 04:00pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 25 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid

Wednesday
3658873 - Study on piezoelectric characterisation of solvent cast PVDF film incorporated with TiO2 and CNF
04:00pm - 04:20pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 25 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
Polyvinylidene fluoride (PVDF) is one of the most outstanding semi-crystalline polymers which generates piezoelectricity when pressure or a mechanical force acts on it. In the present study, polyvinylidene fluoride (PVDF)/TiO2/CNF electroactive film was prepared through solvent casting method by coating the substrate with a Dimethylformamide (DMF) and Polyethylene glycol(PEG) included polymer solution, which was evaporated at room temperature. The crystallization behavior, dynamic mechanical properties, and electroactive properties of the prepared PVDF/TiO2 /CNF electroactive films were investigated by testing methods such as the Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) while the cross-section and the surface of the films were observed under a scanning electron microscope (SEM). The piezoelectric test was conducted by using a Cathode ray oscilloscope (CRO) which projected the desired β phase, the piezoelectric phase obtained by crystallizing the mixed solution of PVDF /TiO2 / CNF. With the positive output voltage values, we conclude that incorporating TiO2 & CNF improved the piezoelectricity of the pure PVDF film. The results indicate that PVDF /TiO2 / CNF composite films can be applied to the fabrication of self-sensing devices such as Heartbeat sensors, Actuators, and Energy harvesting applications

Wednesday
3660895 - Interplay of peptide secondary structure, microphase-separated morphology, and shape memory response in bioinspired peptide-polyurea hybrids
04:20pm - 04:40pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 25 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
Peptides have been used as building blocks for responsive materials due to their tunable hierarchical structure driven by self-assembly behavior. However, few studies have focused on the relationship between secondary structure (α-helix and β-sheet), morphology, and shape memory effect (SME) in peptidic hybrids. To expand this understanding, we probed the impact of secondary structure and hierarchical organization on thermo-responsive shape memory properties by utilizing bioinspired peptide-polyurea hybrids. Peptide motifs were incorporated to the soft segment of non-chain extended polyureas as poly(β-benzyl-L-aspartate)n-b-poly(dimethylsiloxane)-b-poly(β-benzyl-L-aspartate)n (PBLAn-b-PDMS-b-PBLAn) to control the soft segment ordering and degree of phase segregation driven by secondary structure. The α-helical arrangement stabilized by intra-molecular hydrogen bonding led to a microphase-separated and hierarchically-ordered morphology, resulting in an increase of the shape fixing ratio. In contrast, β-sheet ordering yielded a lower shape fixity, which was attributed to a phase-mixed structure via extensive inter-intermolecular hydrogen bonding between the hard block and peptide segments. These findings suggest that, while a microphase-segregated morphology is critical for shape memory performance, the inclusion of peptide building blocks provide an additional handle of SME due to variations in secondary structure. We also explored the effect of thermal annealing on the shape memory behavior of these peptide-polyurea hybrids to demonstrate the tunability of this platform. Overall, this research highlights the role of hydrogen bonding arrangement (inter- vs. intra- molecular) and hierarchical structure on shape memory response.
Wednesday
3658751 - Withdrawn
04:40pm - 05:00pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 25 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid

Wednesday
3659775 - Development of a mobile detection system in handheld format for the quantitative determination of vicinal diketones from green beer
05:00pm - 05:20pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 25 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
Quality assurance of beer and the monitoring of the brewing process are important challenges for every brewery. The vicinal diketones (VDKs) play an essential role as quality parameters in the maturation of beer and in the determination of the optimal storage time.
An important representative among the VDKs is the diketone diacetyl, which causes an off-taste in beer even at relatively low concentrations. It is formed during the fermentation process, but is gradually degraded during beer aging.
A major disadvantage of the analytical methods established to date is that the concentrations of diketones in beer in the range of 0.01 to 0.1 mg/l are too low for the analytical methods to be carried out directly. Therefore sample preparation using a more complex enrichment method (e.g. steam distillation, headspace GC) is required for such an analysis, which has so far practically excluded simple on-site analysis.
The aim of this research project is the development of a mobile measuring unit for fast enrichment and detection of VDKs from green beer. Here we report on the use of hydrogels based on polyacryloylhydrazide (PAH) to capture diketones from beer and release them again for detection. Crosslinked polyacryloylhydrazide was synthesized by reacting polymethyl acrylate with hydrazine. The polymer was then crosslinked with diethyl malonate to form a hydrogel. The reaction of the hydrazide group with the diketones in green beer to form hydrazones and the reversibility of this bond makes this polymer system suitable for separating the diketones. Subsequent acid-catalyzed hydrolysis in a smaller volume releases the diketones in significantly higher concentration and purity for photometric determination. This makes it possible to enrich diacetyl from a beer sample in such a way that the diacetyl content can then be determined photometrically using UV/VIS spectroscopy with a detection limit of up to 0.01 mg/l.

Wednesday
3657297 - Structure-based coarse graining of homopolymer solutions using PRISM theory: Designing the implicit-solvent model from an explicit-solvent model OnDemand
05:20pm - 05:40pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 25 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
Implicit-solvent (IS) models are widely used in molecular simulations of solutions, with the advantage of dramatically saving the amount of computation and the hope of faithfully reproducing some properties of the corresponding explicit-solvent (ES) model. In practice, however, an IS model often gives qualitatively different results from the corresponding ES model. In this work, we take a simple model system of homopolymer solutions as an example to examine the features of the effective pair potential between polymer segments in the IS model that is designed, using the well-developed polymer reference interaction site model (PRISM) theory, to reproduce the pair correlation functions between polymer segments in the corresponding ES model. To assess the accuracy of the PRISM theory, we also quantitatively compare its predictions with Monte Carlo (MC) simulation results, both for the ES model.
Wednesday
3661444 - Micellar structure of the hydrophobically modified polyethylene oxide (PEO): A combinational study of scattering and molecular dynamic simulations
05:40pm - 06:00pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 25 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
Polyethylene oxide (PEO) end-capped with cholesterol (Chol-PEO-Chol) has been used as linkers in order to form interconnected network (gel) for biomedeical applications. In this presentation, we will demonstrate that Chol-PEO-Chol forms flower-like micelle, which is confirmed by combination of experimental methods and molecular dynamic simulations. The critical micelle concentrations of the polymers increase with the molecular weight of PEO as determined by fluorescence spectroscopy and dynamic light scattering. The overall size and internal structure of such micelles were also determined through dynamic light scattering, small angle neutron and X-ray scattering. The small angle scattering data were simultaneously fitted with a core-two-shell model, revealing a nearly dry cholesterol core, an inner and outer shell of PEO with approximately 50% and 88% of water content, respectively. The dimension and water contents are consistent with the MD simulation outcomes, validating the formation of flower-like micelles. In case of 10k and 20k, coexistence of unimers and flower-like micelles are found presumably due to an increase in the hydrophilicity of the Chol-PEO-Chol. Lastly, aggregation number (Nagg) of micelles are estimated to be practically invariant with respect to the molecular weight of PEO.
General Papers/New Concepts in Polymeric Materials:
02:00pm - 06:00pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 24 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
Division/Committee: [PMSE] Division of Polymeric Materials Science and Engineering
Wednesday
3654745 - Dynamic color change in electrospun nanofibers
02:00pm - 02:20pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 24 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
The design of soft materials that change their optical properties in response to a variety of external stimuli is one step towards mimicking the dynamic color changing systems that are observed in nature. We present a simple, multi-responsive system where the interference colors of core/sheath nanofibers and nanofibrous mats can be dynamically tuned with confinement (i.e. fiber diameter), temperature, and UV/Vis irradiation. Nanofibers are fabricated using coaxial electrospinning with a nematic liquid crystal core and a polymer sheath. The result is a soft, flexible mat of material that displays distinct interference colors on a macro (mm) and micro (µm) scale. A Raith-Sørensen interference color chart is calculated and is consistent with the colors observed in electrospun fibers demonstrating the ability to precisely tune the interference color by modifying the fiber diameter to achieve the desired color. We show the color can be tuned both thermally and photochemically leading to a multiple stimuli-responsive system that displays ideal properties for use in “smart” textiles for wearable soft sensors and fabrics.
Wednesday
3654849 - Revealing the melt and solvated aggregation of π-conjugated polymers with large-scale atomistic molecular dynamics
02:20pm - 02:40pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 24 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
Recent synthetic efforts to design polymer-based materials for electronics and optical applications offering mechanical deformability while maintaining efficient semiconducting characteristics have incorporated small alkyl segments directly into otherwise π-conjugated polymer backbones. Here, a family of diketopyrrolopyrrole-tetrathiophene (DPP-4T) variants is explored in melt via large-scale atomistic molecular dynamics (MD) simulations to examine the effect of alkyl segments incorporated into the polymer backbones on the polymer structure, dynamics, and thermal properties. Longer alkyl segments lead to polymer chains that are more flexible, compact, and mobile, with lower thermal transitions for the condensed phase. Further, the chain structures and solution-phase aggregation of experimentally relevant polymer chains are explored via MD of long (~100 kDa) π-conjugated polymer chains of the related polymer family diketopyrrolopyrrole-dithienothiophene (DPP-DTT) in explicit chlorobenzene solvent, with the aim of connecting solution-state structures and dynamics with polymer structures identified in the solid state.
Wednesday
3655353 - Controlled fabrication of MOF-polymer composites with hierarchical pore structure via high internal phase emulsion templates
02:40pm - 03:00pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 24 (Marriott Marquis San Diego Marina)
Dr. He Zhu, Presenter
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
Materials with hierarchical pore structure are widely found in nature. These materials have macropores for rapid transport, micropores for sufficient exchange/reaction, and mesopores that act as channels between the macropores and micropores. Metal-organic frameworks (MOFs) are an emerging class of porous organic-inorganic hybrid materials with high porosity, large specific surface area, and high thermal stability, which are showing great potential in various fields such as gas storage, separation, chemical sensors, and catalysis. The construction of polymer composites with hierarchical pore structure using MOFs as basic building blocks can improve the mass transfer performance of the materials, while solving the problem that MOF particles are not easy to handle and recover, thus enhancing their applications in various fields. This work demonstrates a facile strategy for the construction of MOF-polymer hierarchically porous monoliths via high internal phase emulsion templates. The obtained materials show good performances in the environmental applications.
MOFs stabilized high internal phase emulsions

MOFs stabilized high internal phase emulsions


Wednesday
3658013 - Reversible shape- and color- tunable block copolymer particles driven by photoisomerizable surfactant OnDemand
03:00pm - 03:20pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 24 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
Polymer particles that switch their shape and color in response to light are of great interest to develop programmable smart materials. Herein, we report block copolymer (BCP) particles with reversible shapes and colors, activated by irradiation with UV and visible lights. This shape transformation of the BCP particles is achieved by a spiropyran-based surfactant (SP-DTAB) that changes its amphiphilicity upon photoisomerization. Under UV light (365 nm) irradiation, the hydrophilic ring-opened merocyanine form of SP-DTAB surfactant affords the formation of spherical, onion-like BCP particles. In contrast, when exposed to visible light, surfactants with the ring-closed form yields prolate or oblate BCP ellipsoids with axially stacked nanostructures. Importantly, the change in BCP particle morphology between spheres and ellipsoids is reversible over multiple UV and visible light irradiation cycles. In addition, the shape- and color-switchable BCP particles are integrated to form a composite hydrogel, demonstrating their potential as high-resolution displays with reversible patterning capabilities.
Wednesday
3656290 - Transesterification vitrimers activated by fluorinated groups
03:20pm - 03:40pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 24 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
Vitrimers are polymer networks in which associative exchange reactions can take place under specific conditions, and confer reprocessability to the insoluble materials. Recently, catalyst-free vitrimers have emerged as a new generation of vitrimers able to overcome potential leaching, ageing and sintering issues of catalysts and to ensure the preservation of the vitrimer properties after numerous reshaping processes. Here, we present a novel approach to prepare catalyst-free transesterification vitrimer. The transesterification reactions usually catalyzed using an organometallic complex or a nucleophile, are, in our materials, activated by the presence of fluorinated groups located at the alpha or beta position of the ester groups. Due to the high electron-withdrawing effect of fluorine, these activating groups not only vastly accelerate the network formation (acid ring opening reaction of epoxydes) but also strongly promote the transesterification reactions at relatively low temperaure (150°C), thus allowing easy reshaping of polymer networks. This original approach, very efficient for transesterification vitrimers, is likely also applicable to other Covalent Adaptable Networks relying on other exchange reactions.
Wednesday
Intermission
03:40pm - 04:00pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 24 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid

Wednesday
3654548 - Development of polymer gels for atmospheric water harvesting OnDemand
04:00pm - 04:20pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 24 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
In drought prone areas and other regions without potable water, sustenance of life becomes challenging. To address this problem, it is critical to develop novel materials and methodologies for harvesting atmospheric water. Furthermore, for effective moisture collection the materials need to be thermally responsive, in order to switch between moisture absorbing and moisture releasing at low temperatures (between 40 and 50°C). One promising category of materials for effective atmospheric water harvesting is polymer based, moisture absorbent hydrogels.
In this research several moisture absorbent hydrogel were synthesized and their performances for atmospheric water harvesting were evaluated. The gels consisted of two main components, a water absorbent material, such as polypyrrole doped with chloride, and a polymeric network, such as poly N - isopropylacrylamide, for storing the absorbed water. The performance of the gels for capturing atmospheric water (measured as percent increase in mass over time) was evaluated at different temperature and relative humidity conditions. Furthermore, the performance of the gels over multiple cycles of absorption and desorption of water was evaluated. The results showed significant promise for real world atmospheric water harvesting to generate potable water.

Wednesday
3655665 - Self-assembly and conductivity studies of Fmoc-tripeptides containing histidine and aspartic acid: An investigation of structure, morphology, and applications
04:20pm - 04:40pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 24 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
While the self-assembly of small peptides has been widely investigated for a myriad of biomaterials applications, their ionic transport properties remain largely underexplored, particularly within the Proton Exchange Membrane Fuel Cell (PEMFC) realm. This presentation explores the self-assembly and conductivity properties of Fmoc-supported, Histidine- and Aspartic Acid-based tripeptides, as more sustainable, greener alternatives to catalyst ink layers. These small molecules self-assemble into gels held together via hydrogen bonds, charge, and hydrophobic interactions. Characterization data indicate the presence of β-sheets, therefore facilitating the formation of proton wires. Additionally, impedance studies in bulk and thin films show promising conductivity values, which present an opportunity for re-imagining perfluorinated PEMFC catalyst ink layers through N- and O-accepting/donating, side chain moieties, leading to vehicular transport at high relative humidity. While the ionic transport properties of H- and Asp- peptides are still to be fully understood, a relationship between β-sheets, proton transfer and humidity presents a positive outlook for the future of engineering self-assembled peptides for energy applications.
Wednesday
3644101 - Sulphur copolymer via emulsion polymerization: Synthesis, characterization, and application perspective OnDemand
04:40pm - 05:00pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 24 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
Numerous studies have manifested the concern of heat and mass transfer loss for sulfur copolymers generation via inverse vulcanization. To overcome the mass and energy losses, sulfur-acrylic copolymers synthesized via emulsion polymerization. An outlook for the preparation of sulfur-acrylic emulsion at high temperature in an aqueous medium was provided. Conducted indagating aims to provide a method for the preparation of elemental sulfur copolymers via emulsion polymerization. Acrylic monomers (acrylic acid, butyl methacrylate, methyl methacrylate) and styrene evolved with elemental sulfur to generate the crosslinked structure polymer in the presence of surfactants and initiator. Emulsion polymerization technique help to control the reaction kinetics and enhance the yield. The monomeric compounds are polymerized in the presence of emulsifiers Sodium dodecyl sulfate and Triton X-114 to form stabilized micelles using Potassium persulfate (KPS) polymerization initiator. Formation of sulfur-acrylic-emulsion (SAE) polymer is confirmed by XRD, FTIR, SEM, TEM, DSC, and TGA. Prepared emulsion polymers can be easily processed into thin film at room temperature. XRD and DSC results confirm that crystalline sulfur is completely converted to amorphous form of polymer, and FTIR indicate the reaction completion and presence of C-S bonds. TGA results validate the thermal properties strapped with increasing crosslinking density. SEM and TEM images used to analyze the surface morphology of sulfur co-polymer which present the core-shell structure as shown in the Figure. The prepared polymer exhibits the potential properties to utilize as cathode material for lithium sulfur batteries as well as for water treatment applications.

Wednesday
3643998 - Infectivities of influenza H3N2 and feline calicivirus infectivity on some surfaces of polymeric materials
05:00pm - 05:20pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 24 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
Since the pandemic of COVID-19, people are concerned about the viral infection and sensitive to them. The infection could occur not only through human or animals, but also innanimated matters. If so, how long could viruses and bacteria could be active on materials surfaces? Such an information should be valuable as important characteristics for materials' surfaces. There might be many methods to invesitigate the characteristics. Since 2019, an International Standard (ISO 21702) has been established to evaluate the activity of virion on materials' surfaces. In this experiment, we used Influenza (H3N2) and Feline Calicivurs, checked the viral activities on some polymer sheets such as PE, PP, Silicone and ABS according to the ISO, compared the results and discussed the differences from the viewpoint of materials surface characteristics.
Wednesday
3655448 - Synthesis of high MW and strength polyisobutylene-based polyurethane and its use for the development of a synthetic heart valve
05:20pm - 05:40pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 24 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
Polyisobutylene-based polyurethanes (PIB-PUs) containing approximately 70 wt.% PIB are biocompatible, biostable and calcification resistant thermoplastic elastomers (TPEs) of moderate cost for long term implantable medical devices. These TPEs have outstanding hydrolytic, oxidative, and enzymatic resistance, together with exceptional softness, barrier properties, low creep and low cell adhesion. The inert continuous PIB (-CH2-C(CH3)2-) soft segments shield the environmentally vulnerable urethane (-NHCOO-) hard segments and lead to exceptional biostability. Over the last decade several studies have been carried out to improve PIB-PU properties. However, we are unaware of disclosures of high molecular weight PIB-PUs with high mechanical properties. Herein we disclose the synthesis of PIB-PU containing 70 wt.% PIB with Mn >100 kDa exhibiting 32 MPa ultimate strength and 630 % elongation. The synthesis was achieved by precisely controlled stoichiometry and using highly purified reagents. These PIB-PUs are designed for biomaterial applications where earlier PIB-PUs could not be used.

Wednesday
3656150 - Thermo-responsive salogels with dynamic covalent bonds for shape stabilization of an inorganic phase change material
05:40pm - 06:00pm USA / Canada - Pacific - March 23, 2022 | Location: Pacific Ballroom: Section 24 (Marriott Marquis San Diego Marina)
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Hybrid
Inorganic salt hydrates are of interest as phase change materials (PCMs) because of their high latent heat of fusion, high volumetric energy storage density, enhanced thermal conductivity, and non-flammability compared to their organic counterparts. However, their low viscosity and flowability above their melting point leads to problems such as phase separation, leakage, and corrosion in thermal management applications. Our group previously demonstrated the ability of poly(vinyl alcohol) (PVA) to form thermo-responsive physical gels in the high salinity environment of salt hydrates due to dehydration of polymer chains. In addition, salogels formed from hydrogen bonding between PVA and polyamidoamine dendrimers were shown to shape stabilize lithium nitrate trihydrate (LNH). Here we expand our work to another PCM- calcium nitrate tetrahydrate (CNH), in which PVA formed strong gels containing >95% PCM. ATR-FTIR spectroscopy was applied to reveal the gelation mechanism. The salogels were further strengthened by the dynamic covalent borate ester linkages between PVA and borax to prevent leakage of CNH above its melting point (42 °C). In contrast to the gels in water, PVA-borax salogels were found to be thermo-responsive and could be disassembled reversibly and repeatably allowing for easy filling and removal of PCM from a heat exchanger module. The gel-sol transition temperature, determined from rheology, was highly tunable over a wide temperature range (7-70 °C) and could be controlled by adjusting PVA molecular weight, degree of hydrolysis, borax amount, and pH. Thermal behavior over multiple melting/freezing cycles was found to be repeatable and bulk salogels showed shape stabilization of PCM above its melting point without leakage. The dynamic covalent bonding confers self-healing capability to the salogels, which was demonstrated using both rheology experiments and in bulk salogel samples.