Amphiphilic microgels with a diblock copolymer-like network architecture (each subchain of the network is a diblock copolymer chain) were studied at the interface of two immiscible liquids (oil and water) using mesoscopic computer simulations. It was shown that adsorption of microgels to the interface causes not only deformation of the soft particles, which is primarily controlled by their cross-linking density and incompatibility of the liquids but also microphase separation inside them. One of the blocks is considered to be water-soluble and the other as soluble in oil only, i.e., both liquids are selective solvents for the copolymer. In contrast to dense block copolymer systems, where microphase separation is driven by the incompatibility of the blocks, the microphase separation within the microgel swollen at the interface is solely caused by the incompatibility of the different liquids. Water-soluble blocks uptake water from the water phase, and water-insoluble blocks uptake oil from the oil phase in a proportion, which is determined by a composition of the copolymer. Therefore, the location of the different blocks determines the location of the different liquids, whose incompatibility stabilizes nanodomains. Thus, the subchains remain swollen (each block is swollen in the corresponding liquid) and the incompatibility between blocks alone does not cause microphase separation. Under uniaxial compression of monolayers of such microgels, the morphology of the interfacial ensemble was found to vary from elongated lamellar domains oriented along the compression axis for highly cross-linked particles to onion-like structures for weakly cross-linked particles. Finally, using one-dimensional structure factor analysis and two-dimensional diffraction patterns, the evolution of nanoscale ordering in monolayers during compression was tracked, confirming the emergence of lamellar nanodomains.
Constrained liquid–liquid phase separation in polymer networks is fundamental; however, how nonlinear elasticity modulates the critical threshold remains elusive, particularly in noncovalent lower critical solution temperature hydrogels. To decouple thermodynamics from nonlinear elasticity without altering molecular compatibility, we developed physically crosslinked poly(vinyl butyral) hydrogels. By fixing the degree of acetalization and varying the molecular weight, we utilized chain length to topologically tune the crosslinking density and extensibility. Analysis indicates that thermal memory primarily stems from metastable supersaturation stabilized by elastic constraints. Although the low swelling temperature sets the thermodynamic driving force, the molecular weight determines the strain-stiffening intensity. Crucially, strain stiffening amplifies the elastic penalty of phase separation, establishing a quantitative correlation between critical supersaturation and network elasticity. Consequently, the thermoplastic window is directly driven by the strain-stiffening-modified modulus. Finally, we demonstrated that this hydrogel can serve as an electricity-free time–temperature indicator for cold chains, thereby establishing a mechanothermodynamic framework for the design of topologically smart hydrogels.
Conventional structural designs of proton exchange membranes often fail to decouple ion transport efficiency from the adverse effects of dense polymer chain packing. Consequently, achieving a balance among high proton conductivity, favorable dimensional stability, and superior mechanical toughness remains a formidable challenge. In this study, we present a strategic approach to manipulate the segmental distribution of polycarbazole-based proton exchange membranes by exploiting the positional isomerism of phenyl substitution, thereby promoting the formation of free volume and microphase-separated morphologies. Two isomeric polymers, S-PEM-100 (featuring a rigid linear backbone) and T-PEM-100 (featuring a rigid twisted backbone), were synthesized via superacid-catalyzed polycondensation. Molecular dynamics simulations and CO2 adsorption–desorption measurements revealed that the twisted geometry of T-PEM-100 hinders dense interchain packing, leading to a substantially increased free volume, whereas S-PEM-100 retains compact π–π stacking. Small-angle X-ray scattering (SAXS), atomic force microscopy (AFM), and transmission electron microscopy (TEM) confirmed that this enlarged free volume facilitates the self-assembly of sulfonic acid groups into large, well-connected hydrophilic domains. Consequently, T-PEM-100 achieved a high proton conductivity of 166.9 mS cm–1 at 80 °C and exhibited outstanding performance in both pure water electrolysis and H2/O2 fuel cells. This work provides fundamental insights into leveraging molecular geometry for the design of high-performance proton exchange membranes for sustainable energy applications.
Topological constraints (i.e., chain noncrossing) play a key role in determining the physical properties of polymer materials in industry or the biological functions of biomacromolecules in life, with the entanglement effect in a long-chain linear polymer melt or concentrated solution being a famous demonstration. In this work, we carried out extensive molecular dynamics simulations of the Kremer–Grest model and computationally investigated dynamic features of the intrinsically unentangled (short) linear polymers in melts when a fraction of small rings is added, aiming to uncover an essential role, if existing, of linear-ring threading, a special topological constraint, in polymer dynamics of those intrinsically unentangled linear polymers. Our simulations reveal that, unexpectedly and interestingly, a dynamic slowing down clearly results from the presence of ring molecules in the system of the intrinsically unentangled linear polymers. This conclusion is strongly supported by our simulation results, including mean-square displacement, diffusion constant, and stress relaxation in the linear-ring mixture systems with varying fractions of rings. Furthermore, it is essentially implicated from our simulation results that effective entanglements between those intrinsically unentangled linear polymers are formed by adding rings, which is then confirmed by topological analysis. The underlying physical origin of the effective entanglements being formed, and thus the dynamic slowing down of those short linear chains, lies in the fact that rings act as the bridging molecules, which, via linear-ring threading, topologically link short linear chains together, i.e., forming percolated structures finally.
Abstract Full-color luminescent materials, especially white-light-emissive materials covering the entire visible spectrum, are gaining increasing attention owing to their wide applications. The incorporation of clusteroluminescence into full-color luminescent materials could avoid the aggregation-caused quenching problem of traditional fluorescent dyes. In addition, supramolecular chemistry provides an efficient method to prepare tunable full-color and white luminescent materials through dynamic non-covalent interactions, thereby eschewing tedious organic synthesis and enabling stimuli responsiveness. Herein, we report a full-color and white luminescent system constructed by a supramolecular polymer gel with clusteroluminescence based on pillararenes. This supramolecular polymer gel exhibited unique clusteroluminescence and can serve as a matrix material for different dye molecules to prepare full-color and white luminescent materials. Due to the dynamic properties of the supramolecular polymer gel, the obtained materials showed stimuli-responsive fluorescence emission. Further, this system was successfully utilized in the fields of full-color and white-light-emitting diodes, multicolor inks, and information encryption.
