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Hybrid Functional Materials from Controlled Assembly of Polymer & Inorganic Nanoparticles: Self-Assembly of Polymer & Inorganic Nanoparticles
10:30am - 12:30pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 19
Jie He, Organizer, University of Connecticut; Yao Lin, Organizer; Zhihong Nie, Organizer; So-Jung Park, Organizer, Ewha Womans University; Zhihong Nie, Presider; So-Jung Park, Presider, Ewha Womans University
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
Division/Committee: [PMSE] Division of Polymeric Materials Science and Engineering
Sunday
From 2D assemblies to 3D printed plasmonic sensors
10:30am - 11:00am USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 19
Luis Liz Marzan, Presenter
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
The tumor microenvironment, where numerous cell types interact to create a distinctive physiology, is characterized by deregulated metabolic features. In the recent years, 3D cancer models have been optimized to more accurately recreate and study the complex mechanisms behind tumor metabolism which supports cancer invasion, progression, and response to treatment. Because of the growing interest in studying in situ these complex systems, the development of novel technologies is critical to overcome the existence difficulties. In this context, surface enhanced Raman scattering (SERS) appears as a useful tool for label-free detection and imaging of diverse molecules of interest among the extracellular components. Herein, we present the application of nanostructured plasmonic substrates comprising micropatterned Au nanoparticle superlattices and 3D-printed hybrid scaffolds, to the precise SERS detection of selected tumor metabolites which shape the cancer landscape.

Sunday
Reversible self-assembly of stimuli-responsive polymer-ligated nanocrystals with tunable optical and catalytic properties
11:00am - 11:30am USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 19
Zhiqun Lin, Presenter, Georgia Institute of Technology
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
In this talk, I will discuss a unique amphiphilic-nonlinear-block-copolymer-nanoreactor strategy for crafting stable hairy nanocrystals with light- as well as thermal-promoted reversible and reliable self-assembly and tunable optical and catalytic properties. The size and shape of hairy nanocrystals can be precisely tailored by modulating the length of inner hydrophilic block of nonlinear block copolymers. The permanent anchoring of stimuli-responsive polymers on the nanocrystal surface renders the attractive feature of self-assembly and disassembly of nanocrystals on demand using stimuli of different wavelengths or temperature. Specifically, photo-responsive polymer-ligated noble metal nanocrystals display tunable surface-plasmon resonance absorption and the reversible transformation of nanocrystals between their dispersed and aggregated states. Moreover, thermo-responsive polymer-ligated noble metal nanocrystals manifest controllable catalytic activity in nonmonotontic (i.e., non-Arrhenius-type dependence on temperature) or on/off (i.e., effectively switched “on” and “off” catalysis over temperature) manner over a broad region of temperature. Photo-responsive polymer-ligated all-inorganic perovskite nanocrystals will also be discussed. By extension, this strategy enables the crafting of a family of stable stimuli-responsive nanocrystals and their assemblies for fundamental research in self-assembly and crystallization kinetics of NPs as well as potential applications in optics, optoelectronics, magnetic technologies, sensory materials and devices, catalysis, nanotechnology, and biotechnology.
Sunday
Supramolecular engineering: From Frank-Kasper phase to Quasi-Frank-Kasper phase and quasi-crystals
11:30am - 12:00pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 19
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
Inverse design and inverse thinking are critical steps in the new materials developments (materials genome approach). When we design materials with specific functional properties, we often start with independent building blocks which possess well-defined molecular functions and precise chemical structures. Using the “Molecular Lego” approach, we can then, in some cases with multiple steps, assemble such elemental building blocks together in preferred secondary structures (or packing schemes) to construct materials possessing topologically mandated hierarchical structures with desired functions. In this talk, a unique approach along this inverse design and inverse thinking path will be presented. Various “giant molecules” based on “nano-atoms” are designed and synthesized. “Nano-atoms” refer to shape- persistent molecular nanoparticles (MNPs) such as fullerenes, polyhedral oligomeric silsesquioxanes, polyoxometalates, and folded globular proteins, and others. These “nano- atoms” possess precisely-defined chemical structures, surface functionalities and molecular shapes, which serve as elemental units for the precision synthesis of “giant molecules” via methods such as click chemistry and other efficient chemical transformations. These “giant molecules” include, but are not limited to, giant surfactants, giant shape amphiphiles, and giant polyhedra. These “giant molecules” can assemble into diverse highly ordered building blocks (spherical and non-spherical) to further construct the thermodynamically stable and metastable hierarchical structures By designing of single component and multiple component blending systems, unconventional Frank-Kasper structures, quasi-Frank-Kasper structures and ten-folded quasi-crystals are able to be constructed. This approach has provided a versatile platform for engineering nanostructures that are not only scientifically intriguing, but also technologically relevant.
Sunday
Macroscopic materials assembled from nanoparticle superlattices
12:00pm - 12:30pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 19
Robert Macfarlane, Presenter
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
Nanoparticle assembly has been proposed as an ideal means to program the hierarchical organization of a material by using a selection of nanoscale components to build the entire material from the bottom up. Multiscale structural control is highly desirable because chemical composition, nanoscale ordering, microstructure and macroscopic form all affect physical properties. However, the chemical interactions that typically dictate nanoparticle ordering do not inherently provide any means to manipulate structure at larger length scales. Nanoparticle-based materials development therefore requires processing strategies to tailor micro- and macrostructure without sacrificing their self-assembled nanoscale arrangements. In this talk, we will demonstrate methods to rapidly assemble gram-scale quantities of faceted nanoparticle superlattice crystallites that can be further shaped into macroscopic objects in a manner analogous to the sintering of bulk solids. The key advance of this method is that the chemical interactions that govern nanoparticle assembly remain active during the subsequent processing steps, which enables the local nanoscale ordering of the particles to be preserved as the macroscopic materials are formed. The nano- and microstructure of the bulk solids can be tuned as a function of the size, chemical makeup and crystallographic symmetry of the superlattice crystallites, and the micro- and macrostructures can be controlled via subsequent processing steps. This work therefore provides a versatile method to simultaneously control structural organization across the molecular to macroscopic length scales.

Hybrid Functional Materials from Controlled Assembly of Polymer & Inorganic Nanoparticles: Synthesis of Polymer & Inorganic Nanoparticles
02:00pm - 04:00pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 20
Jie He, Organizer, University of Connecticut; Yao Lin, Organizer; Zhihong Nie, Organizer; So-Jung Park, Organizer, Ewha Womans University; Jie He, Presider, University of Connecticut; Yao Lin, Presider
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
Division/Committee: [PMSE] Division of Polymeric Materials Science and Engineering
Sunday
Controlled self-assembly of conjugated organic polymeric amphiphiles driven by crystallization: Hybrid functional materials with applications in energy funneling
02:00pm - 02:30pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 20
Prof. Ian Manners, Presenter, University of Victoria
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
In this talk recent developments concerning a promising “seeded growth” route to well-defined 1D and 2D nano- and microparticles termed “living” crystallization-driven self-assembly (CDSA), will be briefly described. Living CDSA can be regarded as a type of “living supramolecular polymerization” that is analogous to living covalent polymerizations of molecular monomers but on a much longer length scale (typically, 10 nm – 5 microns). Living CDSA also shows analogies to biological “nucleation-elongation” processes such as amyloid fiber growth.

The building blocks or “monomers” used for living CDSA consist of a rapidly expanding range of crystallizable amphiphiles such as block copolymers, homopolymers with charged termini, or planar p-stacking molecules with a wide variety of chemistries. The seeds used as “initiators” for living CDSA are usually prepared from preformed polydisperse 1D or 2D micelles by sonication. In addition, recent results indicate that living CDSA is scalable.

This talk will focus on the preparation and photophysical properties of hybrid materials which exploit the long exciton diffusion lengths in conjugated polymer nanofibers prepared by living CDSA.

Sunday
Polymer crystallization-driven nanoparticle assembly
02:30pm - 03:00pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 20
Christopher Li, Presenter
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
In recent years, extensive efforts have been devoted to assembling nanoparticles into ordered structures such as 1D chains, 2D sheets, and 3D crystals. Numerous approaches have been reported. Functionalized polymers have been used to crystallize into a variety of patterns for nanoparticle assembly. In this presentation, we will discuss how polymer crystallization can be employed to direct nanoparticle assembly in situ. We will show that nanoparticles can play an integral role in polymer crystallization. Competition between polymer crystallization and nanoparticle close packing leads to a variety of new structures with broken translational symmetry. Furthermore, colloidosomes were successfully used as a unique template to tune polymer crystallization, leading to polymer crystalsomes. We, therefore, envisage that polymer crystallization provides a unique means to guide nanoparticle assembly for functional nanomaterials.
Sunday
Manipulating the interface between polymers and metal–organic framework nanoparticles in aqueous environments
03:00pm - 03:30pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 20
Jarad Mason, Presenter, University of California, Berkeley; Christopher DelRe; Malia Wenny; Joy Cho; Ricardo Sanchez
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
The design of advanced microporous materials is critical to many biomedical and energy-related technologies that require the efficient storage or transport of small molecules, including drug delivery, bioimaging, and gas separations. Despite their high internal surface areas and substantial tunability, metal-organic frameworks (MOFs) are often limited as functional building blocks for these technologies due to chemical decomposition or physical aggregation in water. Although modifying MOF surfaces with polymers can help stabilize and prevent aggregation in colloidal MOF suspensions, the MOF-polymer interface itself is still poorly understood, particularly in aqueous environments. Here, we will discuss efforts to disperse MOF nanocrystals in water using non-covalently associated amphiphilic polymers and to probe the microscopic nature of the MOF-polymer interface in aqueous solutions.
Sunday
Well-defined binary mixed homopolymer brushes grafted on small nanoparticles
03:30pm - 04:00pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 20
Bin Zhao, Presenter
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
Mixed polymer brushes are an intriguing class of surface responsive materials that have been shown to exhibit distinct morphologies under different conditions. When these brushes are grafted on nanoparticles (NPs), the substrate curvature is expected to affect their self-assembled morphologies. Although simulation studies have shown a variety of unique nanostructures formed from mixed brush-grafted small NPs and have suggested a route for the fabrication of multivalent patchy NPs with well controlled number and locations of functional sites, little experimental work has been reported. By immobilizing an asymmetric difunctional initiator (Y-initiator) onto small silica NPs, we have successfully synthesized mixed poly(tert-butyl acrylate)/polystyrene brushes on small NPs with high grafting densities, precisely controlled molecular weights, and narrow dispersities through sequential surface-initiated atom transfer radical polymerization (ATRP) of tert-butyl acrylate and nitroxide mediated radical polymerization (NMRP) of styrene. ATRP and NMRP are two different “living”/controlled radical polymerization techniques, allowing for tuning of the molecular weights of the two grafted polymers independently. Transmission electron microscopy studies reveal that the mixed brushes grafted on small NPs undergo lateral microphase separation when cast from chloroform, resulting in distinct truncated wedge-shaped nanostructures. In contrast, mixed brushes that are grafted on much larger particles self-assemble into more uniform nanostructures.

Hybrid Functional Materials from Controlled Assembly of Polymer & Inorganic Nanoparticles: Synthesis of Polymer & Inorganic Nanoparticles
04:30pm - 06:30pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 22
Jie He, Organizer, University of Connecticut; Yao Lin, Organizer; Zhihong Nie, Organizer; So-Jung Park, Organizer, Ewha Womans University; Jie He, Presider, University of Connecticut; Yao Lin, Presider
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
Division/Committee: [PMSE] Division of Polymeric Materials Science and Engineering
Sunday
Micron-scale soft actuators fabricated from multi-shell polystyrene particle-gold nanoparticle nanohybrids
04:30pm - 05:00pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 22
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
Actuators made of soft matter are needed for a variety of fields ranging from biomedical devices to soft robotics to microelectromechanical systems. While there are a variety of excellent methods of soft actuation known, the field is still an area of intense research activity as new niches and needs emerge with new technology development. Here, we describe a soft actuation system based on a core-multi-shell particle, which moves via photothermal expansion. The system consists of a novel polystyrene-based thermally expandable microsphere, with a secondary shell of a silicate-silane graft copolymer, to which gold nanoparticles are covalently linked. The gold nanoparticles act as photothermal nano-transducers, converting light energy into the thermal energy necessary for microsphere expansion, which in turn results in material movement. Actuation is shown in isolated particles in thermal and photothermal regimes using metal ceramic heaters or 520 nm laser illumination, respectively. Macroscale actuation is demonstrated by making a composite material of particles suspended in the transparent elastomer polydimethylsiloxane. The sample demonstrates an inchworm-like movement by starting from an arched geometry. Overall, this work describes a new particle-based actuation method for soft materials, and demonstrates its utility in driving the movement of a composite elastomer.

Sunday
Ligand design strategies for functional nanoparticle assembly structures
05:00pm - 05:30pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 22
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
Surface Initiated Atom Transfer Radical Polymerization (SI- ATRP) in its various modifications has emerged as a versatile toolbox to control and tailor the properties and interactions of interfaces and to enable the synthesis of hybrid materials with unprecedented property combinations. The resulting materials have attracted interest because the high-level structural control of the architecture of polymer-tethered surfaces enables tailoring of the interactions, microstructure and properties of particulate-based materials.
This presentation will review recent findings regarding the role of polymer modification on the assembly and properties of nanoparticle-based materials. In the first part, the role of polymer modification on the mechanical properties of colloidal assembly structures will be presented. Recent examples of the interplay between phononic and photonic properties in brush particle-based materials will be shown to illustrate how the subtle control of polymer chains at interfaces can instigate novel physical properties in hybrid materials that cannot be realized in ‘classical’ composite materials that are fabricated by mixing of particle and polymer constituents. In the second part, the opportunities to control particle interactions via modulation of polymer graft composition will be discussed. Examples will show how particle organization can be modulated by superposition of microphase separation processes contributed by block copolymer ligands. In the third part, the concept of copolymer brush architectures with lock-and-key interactions will be introduced as a means to enable brush particle assembly structures with self-heal ability.

Sunday
Synthesis and machine learning based analysis of patchy nanoparticles
05:30pm - 06:00pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 22
Qian Chen, Presenter, University of Illinois at Urbana-Champaign
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
I will discuss my group’s two recent progresses on constructing a library of hybrid patchy nanoparticles. Synthetically, we applied the concept of “island formation” established for planar substrates, where ligands cluster as they adsorb, to preparing gold nanoparticles of diverse shapes with precisely sized polymer patches. These polymer patches adapt their configuration in response to external stimulus and modulate the self-assembly behaviors of the nanoparticles. Meanwhile, we applied machine learning based data-mining method to relate synthesis conditions with the patterns of the patchy nanoparticles, to allow for predictive synthesis and design. Such fundamental understanding of the synthesis, interaction and assembly of patchy nanoparticles can bear relevance to their increasing ramifications in addressing staggering national needs in environment, energy, and health.

Sunday
Hybrid gold nanoparticle assemblies: Dendrimer, stars copolymers and e-sensors
06:00pm - 06:30pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 22
Dr Rigoberto Advincula, Presenter, Case Western Reserve University
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
The synthesis of various hybrid nanoparticle-polymer assemblies pre-supposes the ability to utilize various synthetic approaches based on topologically exact grafting methods. The use of dendrimers and star copolymers enables the synthesis of the various hybrid nanoparticle building blocks. Dendrimers can be based on convergent and divergent approaches of carefully designed AB2 monomers to dendrons that can be linked. Star copolymers can be used to graft polymer brushed on nanoparticle surfaces. Here we demonstrate that the use of various dendrimer synthon approaches together with hybrid nanoparticle systems including electropolymerizable moieties afford an excellent assembly protocol to produce
nanostructured coatings, nanopatterns, sensors, and therapeutic agents. We describe polymer assemblies based on conjugated polythiophenes, polybenzylethers, tethered carbazole units, and polyethyleneimine star copolymers, to control the grafting on surfaces and electropolymerization methods. The key to the analysis of such materials is the use of surface-sensitive analytical methods.

Hybrid Functional Materials from Controlled Assembly of Polymer & Inorganic Nanoparticles: Self-Assembly of Polymer & Inorganic Nanoparticles
07:00pm - 09:00pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 20
Jie He, Organizer, University of Connecticut; Yao Lin, Organizer; Zhihong Nie, Organizer; So-Jung Park, Organizer, Ewha Womans University; Zhihong Nie, Presider; So-Jung Park, Presider, Ewha Womans University; Qian Chen, Presider, University of Illinois at Urbana-Champaign
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
Division/Committee: [PMSE] Division of Polymeric Materials Science and Engineering
Sunday
Stabilizing and functionalizing inorganic nanocrystals via metal-ligand coordination interactions
07:00pm - 07:30pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 20
Hedi Mattoussi, Presenter
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
Colloidal nanocrystals made of transition metal cores, prepared via bottom-up solution growth routes, offer great promises for use in wide range of applications and as functional platforms for integration in biomedicine. To facilitate these uses, we have developed a set of high affinity metal-coordinating polymers that are optimally-adapted for surface functionalizing a variety of inorganic nanocrystals. The ligand design exploits the effectiveness of the one-step nucleophilic addition reaction to simultaneously introduce several “custom-adapted” anchoring groups along with solubilizing blocks and reactive functionalities into a single macromolecule. We have more recently used this strategy to test the ability of N-heterocyclic carbene (NHC)-modified ligands to coordinate and stabilize luminescent CdSe-ZnS core-shell quantum dot (QD) dispersions in hydrophilic media. In particular, we probed the effects of ligand structure and coordination on the coating affinity to the nanocrystals. We find that such NHC-based ligands rapidly coordinate onto the QDs (requiring ~ 10 min of reaction time), which reflects the soft Lewis base nature of the NHC groups, with its two electrons sharing capacity. Removal of the hydrophobic cap and promotion of carbene-driven coordination on the nanocrystals have been verified by 1H NMR spectroscopy, while 13C NMR was used to identify the formation of carbene-Zn complexes. The newly-coated QD dispersions exhibit great long term colloidal stability over a wide range of conditions. Additionally, we find that coordination onto the QD surfaces affects the optical and spectroscopic properties of the nanocrystals. These include a size-dependent red-shift of the absorption and fluorescence spectra and a pronounced increase in the measured fluorescence intensity when the samples are stored under white light exposure, compared to those stored in the dark.
Sunday
Withdrawn
07:30pm - 08:00pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 20
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual

Sunday
Self-assembly of the small-sized polymeric Janus particles containing one or a few linear polymer chains
08:00pm - 08:30pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 20
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
The small-sized polymeric Janus particles (SPJPs) are the Janus particles whose one side consists of a polymeric particle with a cross-linked structure, and the other side consists of one or a few linear polymer chains. In the common solvent, SPJPs have a size in the range from a few to a dozen nanometers, comparable to the size of a block copolymer random coil in a good solvent. Similar to an amphiphilic block copolymer, amphiphilic SPJPs have the ability of self-assembling in solution to form regularly structured assemblies that are similar in size and morphology to the assemblies of block copolymers formed in the selective solvent. However, SPJPs have the characteristics of particles, and thus their self-assembly behavior and the structure and properties of the resultant assemblies are quite unique. 1. In the solvent selective for the linear polymer chains, SPJPs can self-assemble at higher concentrations to form regular structures because SPJPs can move more freely due to the less chain entanglements. 2. The particle in the structure of the SPJP make the assemblies different. For example, the SPJPs assemblies formed in the selective solvent of the linear chains have no or much less chain entanglements, so its structure can dissociate under ultrasound; SPJP self-assembly can be used as a general method for preparing the ultrasonic responsive polymer assemblies. In addition, when the SPJP assemblies were formed in the selective solvent for the particle, the strong repulsion between the particles in the shell can lead to dissociation of the assemblies. 3. The particle in the structure of SPJPs provides a versatile platform for functionalization of the assembly. For example, slow covalent crosslinking reactions within the particles can drive morphologic transformation of the assemblies gradually and automatically. Therefore, the linear chain provides the SPJPs excellent self-assembly ability, while the particle provides a versatile platform for regulating the structure and function of the polymeric assembly.
Sunday
Nanocomposite films and assemblies using functional polymers and perovskite nanocrystals
08:30pm - 09:00pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 20
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
Lead halide perovskite nanocrystals (NCs) are emerging as an exciting class of colloidal semiconductors owing to their defect tolerance that enables intense, narrow photoluminescence emission without the need for surface passivation steps. Despite this, these NCs suffer from a lack of chemical (and thus optical) stability, and even all-inorganic cesium lead halides CsPbX3 (X = Cl, Br, I) exhibit a relatively fragile ionic crystal in polar solvents, as well as weakly bound ligand shells. As such, new methods are needed to shield perovskite NCs from degradation, which we are working on from the standpoints of ammonium bromide (ω-NH3Br) terminated polymers as halide precursors for NC synthesis, as well as polymer zwitterions for post-synthetic ligand exchange. This lecture will describe our use of such NC preparation and composite film formation techniques, including NCs assembly into optically transparent nanocomposite films utilizing conjugated polymers as ligands and/or involving NC binding by zwitterionic pendent groups. Nanocomposite structures resulting from these methods retain their photoluminescence emission for months, in some cases even after submerging in water. Looking forward, current investigations into polymer microstructure, zwitterion chemistry, and device fabrication are under investigation with the intention of gaining fundamental insights into perovskite NC structure, chemistry, and stability.

Hybrid Functional Materials from Controlled Assembly of Polymer & Inorganic Nanoparticles: Biointerface of Polymer & Inorganic Nanoparticles
10:30am - 12:30pm USA / Canada - Eastern - August 23, 2021 | Room: Zoom Room 21
Jie He, Organizer, University of Connecticut; Yao Lin, Organizer; Zhihong Nie, Organizer; So-Jung Park, Organizer, Ewha Womans University; Zhihong Nie, Presider; So-Jung Park, Presider, Ewha Womans University
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
Division/Committee: [PMSE] Division of Polymeric Materials Science and Engineering
Monday
Valency control through electron equivalents: The VSEPR equivalent for colloidal crystals
10:30am - 11:00am USA / Canada - Eastern - August 23, 2021 | Room: Zoom Room 21
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
Colloidal crystal engineering of complex, low symmetry architectures is challenging when isotropic building blocks are assembled. Here, we describe an approach to generating such structures based upon programmable atom equivalents (PAEs; nanoparticles functionalized with many DNA strands) and mobile electron equivalents (EEs; small particles functionalized with a low number of DNA strands complementary to the PAEs). Under appropriate conditions, the spatial distribution of the EEs breaks the symmetry of isotropic PAEs, akin to the anisotropic distribution of valence electrons or coordination sites around a metal atom, leading to a set of well-defined coordination geometries and access to three new low symmetry crystalline phases. All three represent first examples of colloidal crystals, with two of them having elemental analogs and the third, a triple double-gyroid structure, having no known natural equivalent.
Monday
Molecular control of the structure and properties of chiral nanoparticle superstructures
11:00am - 11:30am USA / Canada - Eastern - August 23, 2021 | Room: Zoom Room 21
Nathaniel Rosi, Presenter
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
Replacing one atom or linkage in an organic molecule or polymer can dramatically affect its
structure and properties. Chemists have long leveraged the power of synthesis to adjust and fine tune the properties of molecules and materials. Nanoparticles are a class of fundamental structural and functional building blocks for the construction of new materials. The properties of these materials depend on the size, shape, and composition of the constituent nanoparticles as well as their precise organization within the material. In order to fine tune the properties of the material, we must be able to carefully adjust the organization of its component nanoparticles. We are interested in using the power of synthetic chemistry to program and carefully adjust the structure and properties of hierarchical nanoparticle-based materials. This talk deals with peptide-based methods for controlling the synthesis and assembly of nanoparticles into well-defined chiral helical architectures. It will be demonstrated that the atomic make-up of the peptide constructs can be carefully adjusted and that these subtle yet purposeful modifications lead to significant structural changes to the chiral nanoparticle superstructure assembly and properties.

Monday
Structural complexity in chiral nanoassemblies and biomimetic composites
11:30am - 12:00pm USA / Canada - Eastern - August 23, 2021 | Room: Zoom Room 21
Nicholas Kotov, Presenter, University of Michigan
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
The structural complexity of composite biomaterials and biomineralized particles arises from the hierarchical ordering of inorganic building blocks over multiple scales. While empirical observations of complex nanoassemblies are abundant, physicochemical mechanisms leading to their geometrical complexity are still puzzling, especially for non-uniformly sized components. In the recent studies we developed graph theory (GT) for the description of nanoscale materials [1,2] and in this talk, I will describe how it can be applied to (a) chiral hierarchically organized particles (HOPs) with twisted spikes and other morphologies from polydisperse Au-Cys nanoplatelets [1] and (b) nanofibrous composites for batteries [2] and implantable electronics [3].
The complexity of Au-Cys HOPs is higher than biological counterparts or other complex particles as enumerated by graph theory (GT). Complexity Index (CI) and other GT parameters can be applied to a variety of different nanoscale materials to assess their structural organization. As the result of this analysis, we determined that intricate organization of HOPs emerges from competing chirality-dependent assembly restrictions that render assembly pathways primarily dependent on nanoparticle symmetry rather than size. These findings and HOPs phase diagrams open a pathway to a large family of colloids with complex architectures and unusual chiroptical and chemical properties.
Developed GT methods can also be applied to the design of complex biomimetic composites for energy and robotics applications [2] and implantable devices [3] establishing the relations between the functionalities and GT parameters of the biomimetic materials.
<br /> Fig. 1: HOPs self-assembled from chiral (a) and racemic (b) nanoparticles with corresponding graph theory models and complexity indexes (<i>CI</i>) [1].


Fig. 1: HOPs self-assembled from chiral (a) and racemic (b) nanoparticles with corresponding graph theory models and complexity indexes (CI) [1].


Monday
Monolithic bioinspired chiral nematic organization of cellulose nanocrystals with enhanced hydrogen bonding
12:00pm - 12:30pm USA / Canada - Eastern - August 23, 2021 | Room: Zoom Room 21
Division: [PMSE] Division of Polymeric Materials Science and Engineering
Session Type: Oral - Virtual
We present bioinspired crack-free monolithic chiral nematic films in the capillary confinement through a unidirectional flow of cellulose nanocrystals (CNC) with enhanced hydrogen bonding. To achieve the uniform long-range nanocrystals organization during drying, we employed tunicate-inspired hydrogen-bonding-rich 3,4,5-trihydroxyphenethylamine hydrochloride (TOPA) for physical crosslinking of nanocrystals and polyethylene glycol (PEG) as a relaxer of internal stresses in the vicinity of the capillary surface. The CNC/TOPA/PEG film is self-assembled into a left-handed chiral structure parallel to flat walls, and films displayed herringbone organization across the interfacial region. The resulting ultrathin films also exhibit higher mechanical performance than CNC/PEG film with reduced cracks compared to pure CNC films. The chiral nematic ordering of modified TOPA-PEG-CNC material spreads through the entire thickness of robust monolithic films and across centimeter-sized surface areas, facilitating consistent, vivid interference colors, and enhanced circular polarization. Overall, we demonstrate a minimal amount of TOPA molecules in the CNC/TOPA/PEG composite can enhance the ultimate tensile strength and toughness, control the optical reflection peak position, and improve circular polarization.