Reset

Advanced Filters
Structure to Function in Supramolecular Polymers & Materials:
04:30pm - 06:00pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 44
Pol Besenius, Organizer, University of Mainz; Roxanne Kieltyka, Organizer, Universiteit Leiden; John Matson, Organizer, Virginia Tech; John Matson, Presider, Virginia Tech; Rachel Letteri, Presider, Texas A&M University
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - Virtual
Division/Committee: [POLY] Division of Polymer Chemistry
Sunday
Stimuli-responsive metallosupramolecular polymer networks
04:30pm - 04:55pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 44
Dr. Christoph Weder, Presenter
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - Virtual
Supramolecular polymers (SMPs), in which the monomer units are connected by directional secondary interactions instead of covalent bonds, offer properties that merge the characteristics of conventional polymers with the reversible and dynamic nature of supramolecular interactions. The possibility to reversibly disassemble SMPs and shift the equilibrium from macromolecules to oligomers or monomers facilitates their processing and recycling, imparts stimuli-responsive properties, and enables functions such as reversible adhesion, healing, and mechanical morphing. However, most supramolecular polymers exhibit mechanical properties that are inferior to those of conventional commodity plastics. We show here that this problem can be overcome in semicrystalline metallosupramolecular polymer networks. These materials combine attractive mechanical properties, notably high stiffness and strength, with high thermal stability. Such materials can be toughened by creating blends that micro-phase separate into hard and soft domains and optional plasticization. The mechanical properties of these materials can be tuned over a large range by simple variation of the ratio of the two constituents. The option to combine the supramolecular monomers in any ratio further allows the creation of compositionally graded objects in which the mechanical properties can be varied in a spatially controlled manner.

Sunday
The presence of noncovalent interactions in organic semiconductors has been demonstrated to be beneficial in several applications, resulting in the enhancement of charge transport and device efficiency. Particularly, semiconducting supramolecular polymers resulting from hydrogen-bonding interactions have been proven to increase solar cell efficiency by 50%. Nevertheless, the race for achieving efficiency records, has hampered research focused on solving other fundamental issues. Regarding hydrogen-bonding, no comparative studies have been performed, finding scattered examples in literature with different semiconductors, hydrogen-bonding units and without complete studies including both, the optoelectronic and self-assembly properties. The main goal of our research is to understand the role and impact of hydrogen bonds in supramolecular electronics in order to apply them efficiently in devices. Here we show a comparative study using diketopyrrolopyrrole (DPP) as a model electroactive segment and how the results obtained are translated into state-of-the-art materials, such as quinquethiophene-rhodanine and isoindigo derivatives. Different families of hydrogen-bonded DPP supramolecular polymers displaying different hydrogen-bonding parameters (position, number, function, chirality) will be discussed, including photoconductivity measurements, charge transport and spin state correlation in real devices. Finally, the results obtained with DPP will be expanded to the state-of-the art semiconductors, showing the results obtained in rhodanine-based systems.
Diketopyrrolopyrrole conjugated model. Hydrogen-bonded parameters explored. State-of-the-art materials.<br /> Optical, morphological and electrical characterization

Diketopyrrolopyrrole conjugated model. Hydrogen-bonded parameters explored. State-of-the-art materials.
Optical, morphological and electrical characterization


Sunday
Tuning the molecular packing of supramolecular assembly by H-bonding and impact on morphology
05:20pm - 05:35pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 44
Dr. Amrita Sikder, Presenter, University of Birmingham; Prof Rachel OReilly
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - Virtual
Self-assembly is one of the most fundamental characteristics of life. Nature uses self-assembly to build supramolecular materials that possesses fascinating properties (self-healing, adaptive, reconfigurable and responsive) which are fundamental for many complex biological functions. Understanding the self-assembly processes of biological systems facilitates the fabrication of novel supramolecular materials and vice versa. Although significant work has been done in the field of supramolecular self-assembly to develop innovative materials, still it remains a challenging task to precisely control the morphology of a particular self-assembled system and mostly depends on trial and error method. Scientists have long endeavored to develop alluring nanostructures by introducing various noncovalent forces to the constituting building blocks of the amphiphile. Hydrogen-bonding is one of the important noncovalent interaction that can be utilized to generate elegant nanostructure by imparting directionality in the self-assembled systems and DNA double helix, folding of proteins are to name a few that exist in nature. Therefore, exploration of H-bonding mediated self-assembly is of fundamental interest. Here we have demonstrated the impact of H-bonding on supramolecular assembly of structurally near identical -amphiphiles (Scheme 1) by systematically varying the number of H-bonding units. NDI-1 with two H-bonding units formed nanotubes in aqueous medium. Interestingly, when the amide bond was replaced by an ester group, the amphiphile NDI-2 revealed nano-ribbon morphology. Whereas, NDI-3 lacking any H-bonding functionality formed cylindrical micelles. Spectroscopic measurements revealed that H-bonding plays a crucial role in molecular packing which was reflected in the fluorescence properties of the self-assembled systems as well. Highlights of these results will be described in the presentation.

Sunday
Responsive polymers: Hysteresis, bistability, read/write-memory and logic gate function
05:35pm - 06:00pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 44
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - Virtual
Stimuli responsive materials change their state in response to external stimuli. Switching between different states enables to read and write information, and to perform logical operations. This requires reversibity and bistability, which for responsive materials so far has been realized by triggering chemical reactions to drive phase transition between the respective two states.

Here we successfully demonstrate bistability, remanence, reversible write/read information storage and logic gate function for a responsive linear polymers and block copolymers based on the intrinsic hysteresis of the volume phase transition, without chemical reactions. Information can be written by thermal writing on a reflective display using a laser, or simply manually by using heated or cooled pen tips. We furthermore demonstrate a memory function and an AND-logic gate function, which is based on temperature and pH-values as input. We show that the hysteresis is related to cluster domain formation occurring at the volume phase transition, which is a very common phenomenon for thermally responsive polymers such that this principle is applicable to a broad range of responsive materials.

Circular Economy of Polymers:
07:00pm - 09:00pm USA / Canada - Eastern - August 22, 2021 | Room: B2 - EXHIBIT HALL
Dr. Dimitris I Collias, Organizer, Proctor Gamble; Martin James, Organizer, Procter & Gamble Co; John Layman, Organizer
Division: [POLY] Division of Polymer Chemistry
Session Type: Poster - In-person
Division/Committee: [POLY] Division of Polymer Chemistry
Sunday
Withdrawn
07:00pm - 09:00pm USA / Canada - Eastern - August 22, 2021 | Room: B2 - EXHIBIT HALL
Division: [POLY] Division of Polymer Chemistry
Session Type: Poster - In-person

Structure to Function in Supramolecular Polymers & Materials:
07:00pm - 09:00pm USA / Canada - Eastern - August 22, 2021 | Room: B2 - EXHIBIT HALL
Pol Besenius, Organizer, University of Mainz; Roxanne Kieltyka, Organizer, Universiteit Leiden; John Matson, Organizer, Virginia Tech
Division: [POLY] Division of Polymer Chemistry
Session Type: Poster - In-person
Division/Committee: [POLY] Division of Polymer Chemistry
Sunday
Single crystals of mechanically entwined helical covalent polymers
07:00pm - 09:00pm USA / Canada - Eastern - August 22, 2021 | Room: B2 - EXHIBIT HALL
Division: [POLY] Division of Polymer Chemistry
Session Type: Poster - In-person
Double helical conformation of polymer chains is widely observed in biomacromolecules and plays an essential role in exerting their biological functions, such as molecular recognition and information storage. It has remained challenging however to prepare synthetic helical polymers, and those that exist have mainly been limited to single stranded polymers or short oligomeric double helices. Here, we report the synthesis of covalent helical polymers, with high molecular weight, from the achiral monomer hexahydroxytriphenylene through spiroborate formation. Polymerization and crystallization occurred simultaneously under solvothermal conditions, forming single crystals of the resulting helical covalent polymers. Characterization by single-crystal X-ray diffraction shows that each crystal consists of pairs of mechanically entwined polymers. No strong non-covalent interactions are observed between the two helical polymers forming a pair; instead, each strand interacts with neighbouring pairs through hydrogen bonding. Each individual crystal is made up of helical polymers of the same handedness, but the crystallization process produces a racemic conglomerate, with equal amounts of right-handed and left-handed crystals.
Single crystals of a helical covalent polymer have been obtained from an achiral monomer through spiroborate formation. Polymerization and crystallization occur simultaneously to give a network of pairs of entwined helical strands of the same handedness. No strong non-covalent interactions were observed between the two helical polymers forming a pair; instead, each interacts with neighbouring pairs through hydrogen bonding.

Single crystals of a helical covalent polymer have been obtained from an achiral monomer through spiroborate formation. Polymerization and crystallization occur simultaneously to give a network of pairs of entwined helical strands of the same handedness. No strong non-covalent interactions were observed between the two helical polymers forming a pair; instead, each interacts with neighbouring pairs through hydrogen bonding.


Sunday
Withdrawn
07:00pm - 09:00pm USA / Canada - Eastern - August 22, 2021 | Room: B2 - EXHIBIT HALL
Division: [POLY] Division of Polymer Chemistry
Session Type: Poster - In-person

Sunday
Withdrawn
07:00pm - 09:00pm USA / Canada - Eastern - August 22, 2021 | Room: B2 - EXHIBIT HALL
Division: [POLY] Division of Polymer Chemistry
Session Type: Poster - In-person

Sunday
Antibiotic-resistant Gram-negative bacteria are an emergent pathogen, causing millions of infections worldwide. While there are several classes of antibiotics that are effective against Gram-positive bacteria, the outer membrane (OM) of Gram-negative bacteria excludes high molecular weight hydrophobic antibiotics, making these species intrinsically resistant to several classes of antibiotics, including polyketides, aminocoumarins, and macrolides. The overuse of antibiotics, such as b-lactams has also promoted the spread of resistance genes throughout Gram-negative bacteria, including the production of extended spectrum b-lactamases (ESBL). The combination of innate and acquired resistance makes it extremely challenging to identify antibiotics that are effective against Gram-negative bacteria. In this study, we have demonstrated the synergistic effect of outer membrane permeable cationic polyurethanes with rifampicin, a polyketide that would otherwise be excluded by the OM, on different strains of E. coli, including a clinically isolated uropathogenic multidrug resistant (MDR) E. coli. Rifampicin combined with a low dose treatment of a cationic polyurethane reduced the MIC in E. coli of rifampicin by up to 64-fold. The compositions of cationic polyurethanes were designed to have low hemolysis and low cell cytotoxicity, while maintaining high antibacterial activity. Our results demonstrate the potential to rescue the large number of available OM-excluded antibiotics to target normally resistant Gram-negative bacteria via synergistic action with these cationic polyurethanes.

Fourth CME NASA Symposium: Chemistry for Resilient Human Space Exploration:
08:00am - 10:00am USA / Canada - Eastern - August 23, 2021 | Room: A313-A314
Dr. Michael A Meador, Organizer, Meador Aerospace Materials Group, LLC; Prof Robert Nolan, Organizer, The City University of New York; George Rodriguez, Organizer; Ksenia Takhistova, Organizer, Presider, CME; Jonathan Rall, Presider; Dr. Michael A Meador, Organizer, Presider, Meador Aerospace Materials Group, LLC; Mary Kirchhoff, Presider, American Chemical Society
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - Hybrid
Division/Committee: [POLY] Division of Polymer Chemistry
Monday
Introduction to the fourth CME NASA symposium
08:00am - 08:01am USA / Canada - Eastern - August 23, 2021 | Room: A313-A314
Jonathan Rall, Presenter; Dr. Michael A Meador, Presenter, Meador Aerospace Materials Group, LLC
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - Hybrid
POLY in the proud sponsor of the Fourth CME NASA Symposium which Brings Together Industry, Academia, Government and the Public to Enlarge and Enhance the STEM Talent Pool. The goal is to propel cutting-edge developments in chemical sciences to advance human space travel and translate them into new knowledge to improve the lives of people and make their dreams a reality. Join us for these two days packed with inspirational research, industry advances and job trends.

Monday
Ladder of life detection
08:01am - 08:30am USA / Canada - Eastern - August 23, 2021 | Room: A313-A314
Dr. Mary E Voytek, Presenter, NASA Headquarters; Michael New
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - Hybrid
The talk will describe the history and features of the Ladder of Life Detection, a tool intended to guide the design of investigations to detect microbial life within the practical constraints of robotic space missions. To build the Ladder, we have drawn from lessons learned from previous attempts at detecting life and derived criteria for a measurement (or suite of measurements) to constitute convincing evidence for indigenous life. We summarize features of life as we know it, how specific they are to life, and how they can be measured, and sort these features in a general sense based on their likelihood of indicating life. Because indigenous life is the hypothesis of last resort in interpreting life-detection measurements, we propose a small but expandable set of decision rules determining whether the abiotic hypothesis is disproved. In light of these rules, we evaluate past and upcoming attempts at life detection. The Ladder of Life Detection is not intended to endorse specific biosignatures or instruments for life-detection measurements, and is by no means a definitive, final product. It is intended as a starting point to stimulate discussion, debate, and further research on the characteristics of life, what constitutes a biosignature, and the means to measure them.

Monday
Searching for life on ocean worlds
08:30am - 09:00am USA / Canada - Eastern - August 23, 2021 | Room: A313-A314
Mark Nevau, Presenter
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - Hybrid
Several icy moons of the giant planets harbor subsurface oceans. At least one has a chemistry (pH, major elements, redox gradients, simple and macromolecular organic compounds) similar to inhabited places in our ocean. Progress in approaches to searching for life is being infused into ocean moon missions designed to discover either life beyond Earth or the first habitat where life is unseen.
Enceladus Orbilander mission concept for the Planetary Science & Astrobiology Decadal Survey of the National Academies. Credit: M. Neveu/Enceladus Orbilander Concept Study Team/M. Wallace/Applied Physics Laboratory/W0W Inc.

Enceladus Orbilander mission concept for the Planetary Science & Astrobiology Decadal Survey of the National Academies. Credit: M. Neveu/Enceladus Orbilander Concept Study Team/M. Wallace/Applied Physics Laboratory/W0W Inc.


Monday
Nitrogen and habitability on Mars: Insights from missions, meteorites, and terrestrial analogs
09:00am - 09:30am USA / Canada - Eastern - August 23, 2021 | Room: A313-A314
Dr. Jennifer C Stern, Presenter, NASA
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - Hybrid
Life on Earth evolved metabolic pathways to fix atmospheric nitrogen to more biochemically available molecules for use in proteins and informational polymers. For this reason, “Follow the nitrogen” has been proposed as a strategy in the search for life on Mars. We discuss detections of fixed nitrogen on Mars by the Mars Science Laboratory (MSL) Curiosity Rover, recent evidence of nitrogen bearing compounds in Martian meteorites, and nitrogen systematics in terrestrial analogs to illuminate the role of nitrogen in the habitability on Mars.

Monday
NASA composites technology: A chronicle
09:30am - 10:00am USA / Canada - Eastern - August 23, 2021 | Room: A313-A314
Mr. John Vickers, Presenter, NASA
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - Hybrid
Advancements in composites materials and manufacturing supports the future of space exploration as well as national competitiveness needs. NASA research and development efforts in composites materials over the past 25 years has been well integrated across the TRL spectrum. NASA is seeking to take advantage of spacecraft applications that would benefit from substantial weight savings and important cost savings compared to traditional state of the art materials. This presentation examines past and present NASA R&D efforts, together with the technical and cultural barriers, and future directions of research and innovation.

Young Industrial Polymer Scientist Award in honor of Victoria Piunova:
10:30am - 12:15pm USA / Canada - Eastern - August 23, 2021 | Room: A311-A312
J Hedrick, Organizer, Presider, IBM Research
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - Hybrid
Division/Committee: [POLY] Division of Polymer Chemistry
Monday
Aliphatic polycarbonates: A new class of broadly applicable biologics
10:30am - 11:05am USA / Canada - Eastern - August 23, 2021 | Room: A311-A312
J Hedrick, Presenter, IBM Research
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - Hybrid
Amongst these use cases for aliphatic polycarbonates, application to biomedicine requires the most diverse functional group arsenal. Although there exist over 700 1, 3- diols that can be transformed to 6-membered cyclic carbonates, the vast majority of reports use 2,2- bis(hydroxymethyl) propionic acid (bis-MPA) as a foundational building block owing to the cost, ease of installation of functional groups, and since the subsequent monomer is derivatized at the 5-position, distal to the polymerization site, polymerization conditions (ROP) tend to be universal. Similarly, inexpensive and readily available functional 1, 5- diols have been exploited as precursors to 8-membered cyclic carbonates. Transformation of these functional monomers and subsequent polymers have been applied to numerous applications that include drug, gene and cell delivery as well as the use of the polymer as a stand-alone therapeutic including antimicrobials, anticancer agents and antiviral therapies packaged as micelles, hydrogels or coacervates. Specifically, we address the multi-faceted problem of drug-resistance as well as other important concerns in disease treatment exploiting polymer science to develop novel macromolecular therapeutics for treating infectious disease and cancer. Overall, the field of macromolecular therapeutics offers significant promise for improving human health by applying the tools of polymer and supramolecular chemistries together with nanotechnology to create materials for precise, highly effective disease treatment that does not induce resistance.
Monday
Polymeric hydrogels for the fabrication of engineered living materials
11:05am - 11:40am USA / Canada - Eastern - August 23, 2021 | Room: A311-A312
Alshakim Nelson, Presenter
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - Hybrid
Additive manufacturing (or 3D printing) has re-emerged into the spotlight in the last 5 years driven by the rapid progress in hardware and software. Along with these advances, new materials are required to meet the demands of emerging technologies. Herein, we present multi-stimuli-responsive hydrogels designed for direct-write 3D printing. Triblock copolymers based on F127 or poly(alkyl glycidyl ethers) were developed and formulated into stimuli-responsive hydrogels that (1) underwent a reversible sol-gel transition in response to temperature, (2) exhibited shear-thinning behavior, and (3) cross-linked in the presence of UV-irradiation. The syntheses, characterization, and patterning of these materials will be presented. The application of these polymer hydrogels toward printing microbes for immobilized whole-cell catalysis will also be discussed.

Monday
Supramolecular biomaterials enabling innovations in drug formulation and delivery
11:40am - 12:15pm USA / Canada - Eastern - August 23, 2021 | Room: A311-A312
Eric A Appel, PhD, Presenter, Stanford University
Division: [POLY] Division of Polymer Chemistry
Session Type: Oral - Hybrid
Supramolecular biomaterials exploiting rationally-designed non-covalent interactions can enable innovative approaches to drug formulation and delivery. For example, supramolecular interactions can be used to generate dynamically cross-linking polymer networks, yielding shear-thinning and self-healing materials that exhibit viscoelastic mechanical properties similar to biological tissues and flow properties enabling minimally invasive implantation in the body though direct injection or catheter delivery. In this talk we will discuss the preparation, characterization and application of a class of physical hydrogels generated by non-covalent interactions between modified biopolymers (BPs) and nanoparticles (NPs). Owing to the dynamic, non-covalent interactions between the NPs and BPs, the hydrogels flow under applied stress and their mechanical properties recover completely within seconds when the stress is relaxed, demonstrating the shear-thinning and injectable nature of the materials. Moreover, these interactions have been shown to be entropically driven, causing these materials to elicit alternative temperature-dependent mechanical properties than typically observed in physical hydrogels. Further, the hierarchical construction of these biphasic hydrogels allows for multiple therapeutic compounds to be entrapped simultaneously and delivered with identical release profiles, regardless of their chemical make-up, over user-defined timeframes ranging from days to months. These materials have proven to be particularly promising as controlled delivery technologies in vaccines and cancer immunotherapy - applications where precise release of complex mixtures of compounds over prolonged timeframes is crucial. Overall, this presentation will demonstrate the utility of a supramolecular approach to the design of biomaterials affording unique opportunities in the formulation and controlled release of therapeutics.