Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session W26: Self-Assembly of Soft Matter Materials in Multi-Component Solvent SystemsFocus Recordings Available
|
Hide Abstracts |
Sponsoring Units: DSOFT Chair: Yuyin Xi, University of Delaware/NIST Room: McCormick Place W-187B |
Thursday, March 17, 2022 3:00PM - 3:12PM |
W26.00001: Responsive Interfacial Assemblies Thomas P Russell, Shaowei SHi We have developed versatile approach to generate photoresponsive microcapsules by assembling supramolecular NPSs (s-NPSs) at the oil-water interface. Different from traditional NPSs, mainly formed by electrostatic interactions, the s-NPSs used here consist of water soluble α-cyclodextrin (α-CD) modified gold NPs (α-CD NPs) and oil-soluble polymer ligand, azobenzene terminated poly-L-lactide (Azo-PLLA). The host-guest molecular recognition between the α-CD and Azo functionalities can be dynamically controlled by using light as an external trigger, toggling the assemblies encapsulating the microcapsules from a jammed state to an unjammed state, enabling a jamming-controlled diffusion and release of cargoes dispersed in the droplets. Since the size of the droplet can be arbitrarily large or small, this fascinating behavior can also be realized in macroscopic structured liquids having a cubic shape, where the shape of liquids can be changed from a highly nonequilibrium shape to the classic spherical shape with no change in the volume by the jamming-to-unjamming transition of the interfacial assembly of s-NPSs. Similarly, s-NPS, based on the molecular recognition of ferrocene (Fc) and β-cyclodextrin (β-CD) at the oil-water interface. Present an alternative strategy to generate responsive assemblies. Normally, uncharged Fc is strongly bound in the cavity of β-CD by host–guest recognition, whereas the charged Fc+ dissociates rapidly. This association and dissociation effect can be reversibly manipulated by a redox process. As a result, a desirable assembly/jamming and disassembly/unjamming of NPSs is achieved, leading to an efficient encapsulation and release of cargo. The s-NPSs exhibit remarkably high interfacial activity. |
Thursday, March 17, 2022 3:12PM - 3:24PM |
W26.00002: Structural and textural diversity during phase separation of binary mixtures of smectic and isotropic fluids Yuma Morimitsu, Nakyung Kim, Manesh Gopinadhan, Eric B Sirota, Ozcan Altintas, Jonathan D Saathoff, Paul A Heiney, Karen I Winey, Chinedum Osuji Phase separation due to thermally induced demixing in multicomponent liquid-liquid systems is a near-ubiquitous phenomenon; the same can be said regarding precipitation of solids from solution, whether as crystalline or amorphous materials. Here, we explore an intermediate scenario that has been little studied to date. We examine the demixing of structured fluids, liquid crystals, in binary mixtures with solvents. Simple binary mixtures of a smectic-forming mesogen with a long-chain aliphatic solvent show remarkable diversity in phase-separated structures. The structures result from the interplay among interfacial tension, mesogen anchoring, viscosity, and mesophase elasticity, which are parameterized by the composition and temperature of the system. We show that various morphologies can result, including thread-like LC filaments, singly- and doubly-twisted threads, and nematic or smectic droplets with associated defect textures. These results highlight the rich diversity of end-states that are accessible due to the combination of structural anisotropy and fluidity of the LC component. |
Thursday, March 17, 2022 3:24PM - 3:36PM |
W26.00003: Controlling Microphase Separation In Graphene Dispersions - Diffusion-Limited Aggregation to MesoCrystallization David Z Ager, John Texter Advances in polymerized ionic liquids (PIL) have made it feasible to prepare thermodynamically stable dispersions of nanocarbons (SWCNT, MWCNT, graphene) by top-down liquid phase exfoliation processes. A versatile stimuli-responsiveness of some PIL makes it possible to destabilize such dispersions to create interesting materials from fast destabilization in the diffusion-limited aggregation limit to formation of mesocrystals on conformal substrates. We illustrate introductory examples for the case of concentrated aqueous graphene dispersions where destabilization is controlled by varying the ionic solvent components in water that modulate the solvation of the PIL ionic sites. These phenomena can be understood in terms of reversible (pinned) spinodal decompositions exhibited by such PIL in binary solvent systems. Collateral phenomena, including reversible poration, multi-time scale micro-phase separations, isotropic-to-nematic transitions, and rheo-optical effects are also illustrated. |
Thursday, March 17, 2022 3:36PM - 3:48PM |
W26.00004: Aggregation of charge colloidal particles in the binary solvent: not all sizes are equal Yun Liu, Ramon Castaneda Priego, Jose R Villanueva-Valencia It has long been established that when moving the temperature of a binary solvent close to its demixing temperature, an effective attraction can be introduced between colloidal particles, and drive the formation of large particle aggregates. Combining with the results measured by AFM and small angle neutron scattering (SANS), we show that for small charged particles (radius between 5 and 10 nm) in the mixture of water/2,6-lutidine, the particle aggregation is highly sensitive to the particle size. Larger sized particles tend to aggregate first. This size sensitive aggregation is thus potentially a generic particle purification method to separate particles by sizes. Further, this size sensitive aggregation is also observed in samples with much larger particles (average particle size of about 50 nm) with a large size polydispersity. Comparing to the diameter of the particles, the relative range of the attraction of the investigated samples ranges from about 6% to about 60%. Thus, we expect that the observed size sensitive aggregation may work for a wide range of charge particle systems, and may be a generic phenomenon of a system with both an attraction and charge repulsion. |
Thursday, March 17, 2022 3:48PM - 4:00PM |
W26.00005: Tunable Orientation and Assembly of Polymer-Grafted Nanocubes atFluid-Fluid Interfaces Yilong Zhou, Tsung-Yeh Tang, Brian H Lee, Gaurav Arya Self-assembly of faceted nanoparticles is a promising route for fabricating novel nanomaterials but fabricating low-dimensional assemblies with tunable particle orientation is challenging. In this talk, I will demonstrate that trapping surface-functionalized faceted nanoparticles at fluid-fluid interfaces is a viable approach for controlling particle orientation and facilitating their assembly into low-dimensional superstructures. Using molecular dynamics simulations of polymer-grafted nanocubes in a polymer bilayer, we show that the nanocubes can be induced into different orientations by tuning the graft density and their interaction with the two polymer layers. The orientational preference of the nanocubes is found to be governed by an interplay between the interfacial area occluded by the particle, the difference in interactions of the grafts with the two layers, and the stretching of polymer grafts towards the interface. The resulting homogeneously oriented nanocubes were then shown to assemble into unusual architectures, including rectilinear strings, close-packed sheets, bilayer ribbons, and perforated sheets. The assembly approach could therefore be used to fabricate unique arrays of nanoparticles with possible applications in plasmonics, optics, and catalysis. |
Thursday, March 17, 2022 4:00PM - 4:12PM |
W26.00006: Spatiotemporal Evolution of Diffusiophoresis in a 2D Drying of mixed-sized Colloidal Droplet Zhiyu Jiang, H Daniel Ou-Yang Particle segregation during drying of mixed-sized colloidal suspension has been attributed to diffusiophoresis that large particles migrate in the concentration gradient of the small particles. However, diffusiophoresis has not been observed in colloidal mixtures to rule out other effects such as convection or sedimentation which could also give rise to particle segregation. To eliminate sedimentation and convection, an experiment was designed by using an H2O/D2O mixture to match the mass-density of the polystyrene particles and the aqueous solvents. Experiments show the mass-density matching reduced both sedimentation and convection when drying took place in a drop of colloidal suspension confined between two glass slides with a gap of 150 um. Upon drying, a concentration gradient of small fluorescent particles (the majority species) and motion of the different color-labeled large particles (at very low concentration) were measured by time-lapse confocal microscope. The drift speed of large particles was found to depend on both the concentration gradient of the small particles and the salt concentration of the suspension. The ratio of the drift velocity and the concentration gradient, so called diffusiophoretic mobility, was found to decrease with the salt concentration and non-linear with the concentration. These experiments show diffusiophoresis followed only qualitatively with the models developed by Sear and Warren's theories. Sharp drops of the mobility occurred at large density gradient where the absolute densities were also high suggesting the diffusiophoresis motions were hindered by crowding. By eliminating convection and sedimentation, this study quantifies diffusiophoresis in the drying of mixed-sized colloids, and crowding induced hinderance limits the degree of segregation by diffusiophoresis. |
Thursday, March 17, 2022 4:12PM - 4:48PM |
W26.00007: Bicontinuous Biphasic Liquid Emulsions from Ternary Fluid Mixtures Invited Speaker: Daeyeon Lee Bicontinuous interfacially jammed emulsion gels (bijels) are a unique class of soft matter that is produced by arresting spinodal decomposition of biphasic mixtures via interfacial attachment and jamming of particles. Several strategies to form bijels including thermal quenching of homogenous binary mixtures and shearing phase-separated biphasic mixtures in the presence of neutrally wetting particles have been introduced. As a complementary method, we explore the formation of bijels from a homogenous ternary mixture of water, oil and co-solvent. Phase separation is triggered by inducing the removal of the co-solvent via extraction or evaporation. The use of silica nanoparticles and ionic surfactants enables continuous and scalable manufacturing bijels with controllable morphologies and domain sizes down to a few hundreds of nanometers. This presentation will describe the effect of solvent removal process (extraction vs. vaporization) on the morphology and microscale structure of bijels. Surfactant-free bijels stabilized by mixtures of hydrophobic and hydrophilic nanoparticles can be produced; the ratio of these two particles must be changed depending on the polarity of the oil phase, enabling the fabrication of bijels with a wide range of oils of varying polarity. Moreover, we demonstrate that bicontinuous emulsion gels can be produced by inducing partial coalescence of nanoparticle-covered emulsion droplets via nucleation and growth, resulting in bijels with unique microstructures that are substantially different from those observed in spinodal decomposition-based bijels. |
Thursday, March 17, 2022 4:48PM - 5:00PM |
W26.00008: Solvent Segregation Driven Gel (SeedGel) Formation via Self-assembly of Nanoparticles in Binary Solvents Yuyin Xi, Yun Liu Due to the high specific surface area and interconnected channels, bicontinuous structures have found a broad range of applications in energy storage, membrane science, and biomaterials. Here, we report a new type of colloidal gel, solvent segregation driven gel (SeedGel), that successfully stabilizes such bicontinuous channels. SeedGel consists of alternating particle and solvent domains, which is driven by the solvent phase separation using temperature. A model system of nanoparticles in a binary solvent mixture of water/ 2,6-lutidine is used to demonstrate the formation of the SeedGel. Interestingly, the binary solvent also leads to bicontinuous structures with water (particles favor) enriched in the particle domain. Excellent thermo-reversibility and structure reproducibility over multi-length scales are confirmed by the studies using ultra-small angle neutron scattering (USANS) and small-angle neutron scattering (SANS). Ramping rate is shown to accurately control the channel width of the bicontinuous domains. Different binary solvents can be used to adjust the gelation temperature of SeedGel, making it adaptable for various applications over a wide temperature range. And the refractive index of these domains can also be manipulated by controlling the partition of the solvents in different domains to gain interesting optical properties. |
Thursday, March 17, 2022 5:00PM - 5:12PM |
W26.00009: A Generic Explanation of the Mechanism of Co-solvency Xiangyu Zhang, Jing Zong, Dong Meng Mixed solvents are extensively utilized in solution processing of polymers. In solvent mixtures, polymers are often observed to exhibit highly non-trivial behaviors. One example is co-solvency --- polymers that collapse in two different poor solvents become soluble in their mixtures. Explanations based on chemistry-specific arguments are less than satisfactory in carving out a clear physical picture of this intriguing phenomena. In this study, we conduct theorical calculations and computer simulations based on a generic polymer solution model in order to offer a clear account of the driving mechanism of co-solvency. We show that co-solvency results from the composite nature of polymer-solvent interactions, made up of the van der Waals type interactions and associations such as hydrogen bonding. Competition of the two effects gives rise to collapsed conformation when polymers are mixed with each solvent individually. In binary solvent mixtures, cross competitions among the four factors can lead to a swollen polymer conformation at suitable solvent compositions. Implications of the predicted collapse-swelling-collapse transition on the bulk solution phase behavior is further explored using the generic model. The obtained phase diagram compares well with existing experiment data. |
Thursday, March 17, 2022 5:12PM - 5:24PM |
W26.00010: Cononsolvency-induced Micellization of Diblock Copolymers in Multi-solvent Solutions Dong Meng, Xiangyu Zhang Selective solvents are commonly used for inducing micellization of diblock copolymers (DBCs), where the solvophobic and solvophilic blocks form the micellar core and corona, respectively. Here, based on the theoretical concept of cononsolvency developed from our previous studies of multi-solvent polymer solutions, we demonstrate a different path to DBC micellization that is induced by cononsolvent behavior by one of the DBC blocks in a binary solvent mixture. Theoretical calculations and computer simulations will be combined in this study to explore the parameter space in which cononsolvency-induced micellization is stabilized versus macro phase separation, and to characterize the dependence on solvent composition of the critical micelle concentration, the aggregation number, as well as the micellar core-shell structure. Comparing to micelles formed in selective solvent, cononsolvency-induced micelles exhibit sensitive response to solvent composition and allow a greater level of control over morphologies owing to an expanded set of interaction parameters. Findings from this study provide the guiding principles for realizing this new type of micelles in experiments and showcase the versatility in designing polymer self-assembly strategies using multi-component solvent systems. |
Thursday, March 17, 2022 5:24PM - 5:36PM |
W26.00011: Bicontinuous soft solids with a gradient in channel size designed for energy storage applications Job Thijssen, Andrew B Schofield, David J French We present examples of bicontinuous interfacially jammed emulsion gels ("bijels") with a designed gradient in the channel size along the sample. These samples are created by quenching binary fluids which have a gradient in particle concentration along the sample, since the channel size is determined by the local particle concentration. A gradient in local particle concentration is achieved using a two-stage loading process, with different particle volume fractions in each stage. Confocal microscopy and image analysis were used to quantitatively measure the channel size of the bijels. Bijels with a gradient in channel size of up to 2.8%/mm have been created. Such tailored soft materials could act as templates for energy materials optimised for both high ionic transport rates (high power) and high interfacial area (high energy density), potentially making them useful in novel energy applications. |
Thursday, March 17, 2022 5:36PM - 5:48PM |
W26.00012: Self-assembly of two-component soft systems controlled by pairwise interactions. Alberto S Scacchi, Sousa Javan Nikkhah, Maria Sammalkorpi, Tapio Ala-Nissila Self-assembly in natural and synthetic molecular systems can create complex aggregates or materials whose properties and functionalities rise from their internal structure and molecular arrangement. The key microscopic features that control such assemblies remain poorly understood, nevertheless. We demonstrate how the intrinsic length scales and their interplay in terms of inter-species molecular interactions can be used to tune soft matter self-assembly. |
Thursday, March 17, 2022 5:48PM - 6:00PM |
W26.00013: Biomimetic subcellular structures from phase separation of an aqueous two-phase system Huanqing Cui, Ho Cheung Shum Hierarchical subcellular structures synergically regulate essential cellular activities through dynamic assembly. Despite extensive efforts, scientists and engineers have yet to reproduce a similar level of dynamics thoroughly. To understand and eventually demonstrate the dynamic structures and interactions, aqueous two-phase systems (ATPSs), emerge as a promising in-vitro model due to their all-water and biocompatible environment. Here, we design a smart ATPS consisting of poly (N-isopropyl acrylamide) (PNIPAM) and dextran. By regulating concentrations and ambient temperature, biomimetic subcellular structures such as phase-separated droplets and viscoelastic networks are generated through liquid-liquid phase separation and liquid-to-solid phase separation. The reversible changes of PNIPAM configurations from hydrophilic coils to hydrophobic globules enable the resulting ATPS to exhibit the reversible transition between liquid droplets and viscoelastic networks. Understanding the mechanism will enable precise control of the biomimetic subcellular structures, with potential implications on the regulation of the phase separation of biomolecular condensates. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700