Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session S17: Macromolecular Engineering of FormulationsFocus Recordings Available
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Sponsoring Units: DPOLY Chair: Vivek Sharma, University of Illinois Chicago Room: McCormick Place W-184BC |
Thursday, March 17, 2022 8:00AM - 8:36AM |
S17.00001: Engineering polymer brush nanoparticles to disrupt asphaltene aggregation Invited Speaker: Sibani Biswal AA/AMPS is the copolymer of acrylic acid and 2-acrylanmido-2 methylpropanesulfonic acid (AMPS). Due to the carboxylic group (scale inhibition and dispersion) and sulfonic acid group (strong polarity) in this copolymer, AA/AMPS has high salt tolerance. Grafting of poly(AA-AMPS) chains onto iron oxide nanoparticles results in stable dispersions that can tolerate high salinities and temperatures. We will describe how these nanoparticle-polymer formulations can be used to inhibit asphaltene, a class of macromolecules found in crude oils, deposition of mineral surfaces. Asphaltenes have large aromatic cores with a large number of heteroatoms that have a high propensity for aggregation. Our results reveal that AA/AMPS nanoparticles interrupt the aggregation of asphaltenes by disrupting the pi-pi stacking between the aromatic cores. We utilize a porous media microfluidic device that can be used to visualize and measure the dynamics of asphaltene deposition in the presence of the AA-AMPS nanoparticles. New insights into how the nanoparticle-polymer aggregate influences the deposition profile of asphaltene agregates will be described. |
Thursday, March 17, 2022 8:36AM - 8:48AM |
S17.00002: Evolution of Polymer Colloid Structure During Precipitation and Phase Separation Jason X Liu, Navid Bizmark, Douglas Scott, Richard Register, Mikko Haataja, Sujit S Datta, Craig Arnold, Rodney Priestley Polymer colloids arise in a variety of contexts ranging from synthetic to natural systems. The structure of polymeric colloids is crucial to their function and application. Hence, understanding the mechanism of structure formation in polymer colloids is important to enabling advances in their production and subsequent use as enabling materials in new technologies. Here, we demonstrate how the specific pathway from precipitation to vitrification dictates the resulting morphology of colloids fabricated from polymer blends. Through continuum simulations, free energy calculations, and experiments, we reveal how colloid structure changes with the trajectory taken through the phase diagram. We demonstrate that during solvent exchange, polymer–solvent phase separation of a homogeneous condensate can precede polymer–polymer phase separation for blends of polymers that possess some degree of miscibility. For less-miscible, higher-molecular-weight blends, phase separation and kinetic arrest compete to determine the final morphology. Such an understanding of the pathways from precipitation to vitrification is critical to designing functional structured polymer colloids. |
Thursday, March 17, 2022 8:48AM - 9:00AM |
S17.00003: Aqueous formulation of concentrated semi-conductive fluid using polyelectrolyte complexation My Linh Le, Dakota T Rawlings, Scott Danielsen, Rhys M Kennard, Michael L Chabinyc, Rachel A Segalman A processable fluid containing extremely high concentration of conjugated polymer can be formed via the coacervation of a conjugated polyelectrolyte (CPE) with a polymeric ionic liquid (PIL). The phase diagram of the CPE-PIL mixture shows a broad region of coacervation that stretches across all polymer concentrations. The viscous coacervate contains up to 50 wt% polymer, approximately 50 times higher than concentrations commonly achieved in conventional solution processing. This coacervate was blade-coated into solid films of mm-scale thickness with improved CPE conjugation length, likely due to the reduction in backbone torsional disorders. As a result, the electronic conductivity of the complexed film upon subsequent acid doping is twice as high as that of the CPE film, despite the fact that half of the complexed film is composed of an insulator. This work shows that polyelectrolyte complexation is a promising route to the formulation of highly loaded conjugated polymer fluids for industrial-scale fabrication, with added benefits on charge transport through the improved control of the conjugated polymer conformation. |
Thursday, March 17, 2022 9:00AM - 9:12AM |
S17.00004: Effect of the Polymer Glass Transition on Size Stability in Salted Colloidal Dispersions Douglas Scott, Robert K Prud'homme, Rodney Priestley Polymeric nanoparticles (NPs) offer a wide range of available chemistries for use in applications such as interfacial adsorption, self-assembly, and encapsulation. However, to maintain the advantageous properties enabled by their size, NPs must be stabilized via repulsive interactions to minimize aggregation over time. While ionic strength is commonly used to adjust properties of charged NP dispersions, additional formulation handles for tuning species-specific interactions would allow for greater control over dispersion properties and enable use of multi-component particle morphologies. |
Thursday, March 17, 2022 9:12AM - 9:24AM |
S17.00005: Increasing ionic conductivity within thermoplastics melts via commercial additives to enable mesoscale fiber formation from melt electrospinning Laura Clarke, Neelam Sheoran, Brenton D Boland, Samuel R Thornton, Jason Bochinski Electrospinning is a nanofiber formation process that relies on the interaction between ions in a polymer fluid (solution or melt) and an applied electric field. Although fibers produced from melts are expected to have superior mechanical properties (compared to those from solutions), melt electrospinning is notoriously unpopular: the higher viscosity of melts makes it difficult to feed fluid through a narrow needle and is often blamed for large fiber diameters. On the other hand, the role of low ionic conductivity in thermoplastic melts as a barrier to nanofiber formation has been underexplored. We used an unconfined configuration (i.e., needle-free) that mitigates the practical challenges of high viscosity and enables a fundamental study of the length scales impacted by viscosity and those altered by conductivity*. Two polyethylene formulations with different viscosities were utilized and a chemically-compatible commercial anti-static agent was used to introduce additional ionic conductivity. The key role of conductivity in determining the jet radius (which sets the upper limit on the fiber size) is discussed in the context of fluid mechanics theory and previous simulations. Increased conductivity resulted in a 20× decrease in fiber diameter and formation of a significant fraction of sub-micron diameter fibers. Parameters which affect the conversion of the liquid jet to a solid fiber and the pertinent theory are also outlined. *Soft Matter, 2021, DOI: 10.1039/D1SM01101D |
Thursday, March 17, 2022 9:24AM - 10:00AM |
S17.00006: Macromolecular Engineering of Degradable Photocurable Resins Invited Speaker: Travis W Walker Photocurable resins, typically consisting of a combination of multi-functional monomers and oligomers, a photoinitiator, and an optical absorber, are formulated for numerous applications in light-based 3D printing. By strategically incorporating novel, biocompatible, anhydride-based oligomers that are available solely through our innovative synthesis route, formulation development has provided expanded physical properties of 3D-printed materials that chemically degrade in the presence of water. Chemical degradation leads to controlled and predictable erosion of the crosslinked network from the surface inward on a time span of hours, days, or weeks. The physiochemical behavior of the polymer network in unique environments is heavily influenced by incorporation of different degrees of hydrophobicity into the matrix backbone. Practical material-oriented methods of altering the capability for anhydride-based materials to degrade in their solid state at controlled rates include changing the monomers that are used, changing the length of the monomer, changing functionalities that are associated with the ‘R’ group of the polymer (i.e., the internal structure of the monomer), and changing the formulation of the photocurable resin. Characterization techniques for measuring the erosion rate, mechanical integrity, water uptake, and swelling of the parts that are 3D printed upon exposure to water are explored. Future work includes the incorporation of functionalized particles and fillers for advanced applications that require controlled and predictable delivery. |
Thursday, March 17, 2022 10:00AM - 10:12AM Withdrawn |
S17.00007: Unexpected phase behavior in polymer blend electrolytes detected via small angle neutron scattering Kevin W Gao, Rachel L Snyder, Jaeyong Lee, Geoffrey W Coates, Nitash P Balsara Polymer blends are usually immiscible as the entropy gain from mixing is negligible due to the connectivity of long chain polymers. Small angle neutron scattering (SANS) offers an unambiguous method for determining phase behavior by utilizing contrast in scattering lengths. Using SANS, we show that it is possible to obtain homogeneous mixtures of two chemically distinct polymers with a lithium salt for electrolytic applications. This approach is motivated by the success of using mixtures of organic liquids in modern lithium-ion batteries. We study polymer/polymer/salt blend electrolytes with the following polymers: poly(ethylene oxide) (PEO), poly(1,3,6-trioxocane) (P(2EO-MO)), and poly(1,3-dioxolane) (P(EO-MO)). PEO/P(2EO-MO), PEO/P(EO-MO), and P(EO-MO)/P(2EO-MO) blends are all miscible in the salt-free state, but minute salt addition (r = 0.005, where r is the molar ratio of Li atoms in the salt to O atoms in the polymers) leads to phase separation. PEO/P(2EO-MO) and PEO/P(EO-MO) blends become miscible again when salt concentration is increased beyond a critical value (r ≥ 0.075). However, P(EO-MO)/P(2EO-MO) blends remain immiscible for all subsequent salt concentrations, despite their chemical similarity. Our observations are inconsistent with the “like dissolves like” rule. |
Thursday, March 17, 2022 10:12AM - 10:24AM |
S17.00008: The nSoft Autonomous Formulation Laboratory: X-Ray and Neutron Scattering for Industrial Formulation Discovery Peter Beaucage, Tyler B Martin While scattering methods (SAXS, SANS, WAXS) are workhorse techniques for characterizing model macromolecular formulations, they have not been widely used to characterize real products, largely because the large number of components (10-100) often precludes rational mapping between component fractions, structure, and product stability. Multimodal characterization and machine learning (ML) tools promise to greatly reduce the expense of exploring the stability boundaries of a particular, desirable phase in highly multicomponent products. Here we describe the development of the Autonomous Formulation Laboratory, a highly adaptable platform capable of autonomously synthesizing and characterizing liquid mixtures with varying composition and chemistry using x-ray and neutron scattering in addition to a suite of secondary measurements such as optical imaging, UV-vis-NIR and capillary rheometry. We will demonstrate the application of the platform to systems ranging from model block copolymer formulations to industrial systems from personal care, biopharmaceutical, and alternative energy partner companies. Future directions in algorithms and instrumentation to study the far-from-equilibrium self-assembly processes that underlie many real products will also be discussed. |
Thursday, March 17, 2022 10:24AM - 10:36AM |
S17.00009: AC-electrospinning Nanofibers from Polymer-CdTe QD Complex Coacervates JAMUNA K VAISHNAV, Yingxi Elaine Zhu Luminescent nanofibers have emerging popularly in our contemporary scientific community because of their potential applications in developing flexible displays, smart wearable fabrics, fluorescent printing, and etc. However, incorporating luminescent materials, such as quantum dots and (in)organic fluorophores, in polymeric fibers remains practically challenging. Here, we have investigated a facile and rapid ac-electrospinning process to fabricate luminescent flexible, ultralong fibers through complex coacervate of polyethylene (PEG) coated CdTe QDs and polyacrylic acid (PAA), where the complex viscoelasticity can be modified by compositions to enable the nanofiber spinning. Polymer-QD composite nanofibers of varied width and length can be controlled by electrospun jets with regulating the applied AC voltage and frequency. Confocal microscopic characterization of the resulting fibers confirms bright green luminescence of the integrated CdTe QDs uniformly distributed along the entire length of the fibers. Ac-voltage and frequency-dependent fiber diameter are also quantified by SEM characterization The current study showcases the exploitation of coacervate solution to assimilate highly photostable QDs in flexible polymer nanofibers for broad biomedical and nanotechnological applications. |
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