Soft Matter[JOURNAL]
Sun
200 papers
Realizing microrheological response of configurable viscoelastic media with a dynamic optical trap.
Halder S, Khan M
Soft Matter · 2026 Jul · PMID 42300958 · Publisher ↗
The local viscoelastic (VE) environment governs the motion of an embedded microsphere and consequently, pertinent dynamical phenomena. However, studying such phenomena with varying VE properties remains challenging for v...
The local viscoelastic (VE) environment governs the motion of an embedded microsphere and consequently, pertinent dynamical phenomena. However, studying such phenomena with varying VE properties remains challenging for various reasons, including the strong coupling among the VE parameters and their dependence on experimental conditions, such as temperature. Here, we demonstrate the experimental realization of configurable VE media with broad variations, wherein the VE properties can be systematically and independently tuned, employing a dynamic optical trap. Specifically, the dynamics of a particle in a slowly diffusing optical trap provides the linear microrheological response of single-relaxation VE fluids, namely Jeffreys or Maxwell-Voigt (MV) fluids, where the trap strength and its diffusion coefficient regulate the elastic response and the low-frequency viscosity, respectively. The characteristic features in the mean square displacement (MSD) of the trapped particle match those of a probe particle in real MV fluids, and the simulation results follow the harmonically bound Brownian particle with long-time diffusion model describing single-relaxation complex fluids. Our scheme is further validated by demonstrating excellent quantitative agreement between the experimentally observed MSDs of the trapped bead and those from the corresponding analytical predictions. We extend the applicability of this scheme for realizing the microrheological response of double-relaxation VE media by incorporating appropriately correlated noise in the trap trajectory, signifying its validity for any linear VE media with multiple relaxations. Our scheme can be further extended to realize probe particle dynamics in an active VE environment, , an entangled network of active polymers, by translating the trap along an active Brownian trajectory. Therefore, our scheme enables systematic microrheological studies in VE regimes that are otherwise challenging to realize or not readily accessible with real materials.
Beyond pair entropy: orientational many-body correlations in supercooled glass-forming liquids from a four-point structural entropy.
Kushawah S, Chakraborty D, Jose PP
Soft Matter · 2026 Jul · PMID 42300952 · Publisher ↗
The conventional pair entropy, derived from the isotropic radial distribution function (), systematically underestimates structural ordering in supercooled glass-forming liquids. We argue that this failure arises because...
The conventional pair entropy, derived from the isotropic radial distribution function (), systematically underestimates structural ordering in supercooled glass-forming liquids. We argue that this failure arises because , constructed from the isotropic (), is inherently insensitive to the many-body orientational correlations that become accessible only through a four-point conditional distribution evaluated in a local particle-centered frame. To recover this information, we introduce a three-dimensional four-point structural entropy , constructed from the four-point conditional distribution function (,,) evaluated in a local particle-centered reference frame, and derive its exact decomposition into a radial contribution and a weighted orientational entropy . Applying this framework to the canonical KA binary mixture, we find that accounts for a substantial fraction of across the full temperature range studied, reflecting genuine icosahedral and dodecahedral angular ordering present at all temperatures-as independently established by Zhang and Kob-rather than a numerical artifact. These results demonstrate that (,,) encodes angular structural information entirely invisible to the conventional () and to the thermodynamic excess entropy , and that provides a tractable thermodynamic measure of packing-driven orientational ordering across the supercooled regime.
A percolation-based theoretical model reveals the structural origin of strain-stiffening in semiflexible fibrous networks.
Zhou Y, Yang S, Cao L … +8 more , Ren J, Bai R, Yang Y, Peng R, Yao J, Chen X, Shao Z, Ling S
Soft Matter · 2026 Jul · PMID 42300947 · Publisher ↗
Semiflexible fibrous networks are extensively found in biological tissues and engineered materials, exhibiting distinct mechanical properties situated between purely flexible and rigid networks. Understanding the underly...
Semiflexible fibrous networks are extensively found in biological tissues and engineered materials, exhibiting distinct mechanical properties situated between purely flexible and rigid networks. Understanding the underlying mechanisms governing their nonlinear strain-stiffening behavior remains challenging due to limitations in current theoretical frameworks, which predominantly focus on fiber stiffness, crosslinking density, and fiber interactions, without fully addressing changes in the network topology during deformation. Here, we propose a percolation-based theoretical model to elucidate the mechanical response and strain-stiffening behavior of semiflexible fibrous networks under tensile loading. By explicitly defining percolation parameters such as node connectivity, fiber connection probability, percolation threshold, and the rigidity percolation giant component (RPGC), we quantitatively correlate the microscopic fiber rigidity transitions with macroscopic network mechanics. Our molecular dynamics simulations combined with graph theory analysis demonstrate the central role of RPGC formation in the transition from non-affine to affine deformation regimes. Numerical results confirm that our percolation model captures the nonlinear stress-strain trend observed in simulation, particularly the onset of strain-stiffening. Additionally, we identify a three-stage deformation behavior: initially non-affine, transitioning to entropy-driven affine deformation, and ultimately dominated by enthalpic affine deformation, which provides detailed insights into the microstructural evolution of fibrous networks under strain. This percolation-based framework offers a comprehensive mechanistic understanding of semiflexible fiber networks, which may inform the rational design and optimization of biomimetic materials and engineered network structures.
Modeling the organizational heterogeneity of cholesterol-enriched microdomains in the neuronal membranes of gray and white matter of Alzheimer's brain: a computational lipidomics study.
Peesapati S, Chakraborty S
Soft Matter · 2026 Jul · PMID 42300919 · Publisher ↗
Alzheimer's disease (AD) is a leading cause of death among the elderly, with no existing treatment. The development of therapies is further hindered by a limited understanding of the molecular pathogenesis and the absenc...
Alzheimer's disease (AD) is a leading cause of death among the elderly, with no existing treatment. The development of therapies is further hindered by a limited understanding of the molecular pathogenesis and the absence of reliable early-detection biomarkers. Neuroimaging and lipidomic studies reveal structural and biochemical alterations in both gray and white matter in AD patients, including disruptions in membrane organization and neuronal signaling pathways. In the present work, we employed lipidomics-guided modeling of membranes in gray and white matter regions under healthy and diseased (AD) conditions, and used all-atom molecular dynamics (MD) simulations to examine how AD-associated alterations in lipid composition influence the structure, spatial organization, and micro-heterogeneity of neuronal plasma membranes. The data suggest that Alzheimer's disease-associated lipid alterations in gray matter (GM) and white matter (WM) impact membrane thickness and microdomain distribution, highlighting the critical role of lipid composition in maintaining neuronal membrane homeostasis and function. Higher-order cholesterol-ceramide-sphingomyelin-enriched domains are more abundant in the neuronal membranes of the GM region under diseased conditions. Under AD-mimicking conditions, lipidomic analyses demonstrate that neuronal membranes in GM experience more substantial compositional and structural remodeling than those in WM. Our results show significant changes in membrane microdomain distribution across the lipid bilayers, and, interestingly, these changes are more pronounced in the gray matter than in the white matter. This study establishes a framework for modeling the tissue-specific lipidomics data to understand how disease-driven compositional changes affect the structure, organization, and dynamics of biological membranes.
Ionic microsphere-reinforced multifunctional conductive hydrogel sensors for human motion monitoring.
Ren J, Wang Y, Zhang W … +3 more , Zhou Z, Li Y, Yang W
Soft Matter · 2026 Jul · PMID 42300898 · Publisher ↗
Hydrogel-based flexible sensors are attractive for wearable electronics because of their softness, conformability, and tissue-like mechanics. Nevertheless, integrating high toughness, robust adhesion, self-healing abilit...
Hydrogel-based flexible sensors are attractive for wearable electronics because of their softness, conformability, and tissue-like mechanics. Nevertheless, integrating high toughness, robust adhesion, self-healing ability, anti-freezing capability, and reliable strain sensitivity into a single hydrogel remains challenging. Here, we report a multifunctional conductive hydrogel in which ionic liquid-functionalized microspheres (MS) are introduced into an oxidized xanthan gum/chitosan (OXG/CS) matrix to serve as reinforcing nodes, dynamic physical crosslinking sites, and sacrificial energy-dissipation units. The microspheres interact strongly with the surrounding polymer chains through hydrogen bonding and electrostatic interactions, while the OXG/CS network provides reversible imine bonds. This hybrid dynamic network markedly improves the mechanical performance of the hydrogel, yielding an elongation at break of more than 970%, a toughness of 320 kJ m, and strong interfacial adhesion, while retaining excellent self-healing behavior. The incorporation of ionic species also endows the hydrogel with high conductivity (4.1 S m) and excellent anti-freezing performance. As a strain sensor, the hydrogel exhibits high sensitivity, with a gauge factor of 6.70 in the 100-600% strain range and can reliably detect subtle physiological signals such as pulse waves and vocal-cord vibrations. These results demonstrate that ionic microsphere reinforcement is an effective strategy for constructing multifunctional hydrogel sensors for use in complex environments.
Underwater mussel-inspired adhesive formed by simple coacervation.
Gimenez G, Parron A, Rufino A … +5 more , Lapeyre V, Goudeau B, Douliez JP, le Coz C, Perro A
Soft Matter · 2026 Jun · PMID 42300761 · Publisher ↗
Mussels possess a remarkable natural ability to adhere on wet surfaces such as rocks in marine environments. This adhesion is attributed to proteins that undergo phase separation to form coacervates. These coacervates ca...
Mussels possess a remarkable natural ability to adhere on wet surfaces such as rocks in marine environments. This adhesion is attributed to proteins that undergo phase separation to form coacervates. These coacervates can further assemble into systems that evolve into structured fluids, where a polymer-rich viscoelastic phase becomes continuous while the solvent-rich phase remains dispersed. Here, we report a poly(acrylic acid)-based system functionalized with cationic and hydrophobic moieties that reproduces key features of this behavior. Upon pH variation, the polymer undergoes self-coacervation, leading to the formation of dense droplets. These droplets progressively sediment and coalesce, resulting in a local increase in concentration. This process is accompanied by a transition toward a continuous polymer-rich phase in which water droplets are retained, consistent with a phase inversion driven by concentration increase. Rheological measurements show that this transition is associated with a marked increase in viscoelasticity and interfacial adhesion, as quantified by tack measurements. These results highlight how the balance between electrostatic and hydrophobic interactions governs the transition from a dispersed coacervate state to a continuous viscoelastic material with adhesive properties. This bioinspired system offers a promising strategy for the development of effective underwater adhesives and opens new avenues in the design of biomimetic materials for wet-surface bonding applications.
Formation of assembloids by DNA-mediated synthetic cell self-assembly.
Burgstaller A, Lopez EAL, Hwang GM … +2 more , Jahnke K, Staufer O
Soft Matter · 2026 Jul · PMID 42300727 · Publisher ↗
Approaches in tissue engineering, organoid culture, and organs-on-chip have propelled the development of increasingly sophisticated models of human tissues. However, as they are formed from natural cells, it is challeng...
Approaches in tissue engineering, organoid culture, and organs-on-chip have propelled the development of increasingly sophisticated models of human tissues. However, as they are formed from natural cells, it is challenging to control their molecular composition and biophysical properties, increasing variability and limiting their robustness. To overcome these limitations, we introduce a self-assembly strategy for synthetic cells that enables the formation of millimeter-sized synthetic constructs based on single synthetic cells. Specifically, we functionalize the lipid membrane of synthetic cells with cholesterol-tagged single-stranded DNA aptamers, which drive programmable intercellular adhesion through sequence-specific hybridization. This allows individual synthetic cells to interconnect into higher order 3D constructs. By varying aptamer complementarity, internal architecture with spatially distinct functional zones and tuneable mechanical properties can be encoded. Most importantly, the DNA-driven self-assembly operates directly in cell culture medium, is compatible with high-throughput microwell formats enabling scalable screening workflows and is reversible by DNA displacement. To demonstrate the biological functionality of these synthetic tissues, we incorporate T cell-stimulatory antibodies into spatially segregated tissue regions. This design mimics lymph node organization and supports infiltration of natural primary human T cells, which subsequently expand within the synthetic tissue. Together, these results establish a route to tissue-scale matrices built from synthetic cell collectives and represent a critical step toward functionally integrating living and non-living matter.
Enhancing electromechanical responsiveness of PVC gels ion size control.
Takahashi K, Urakawa O, Inoue T
Soft Matter · 2026 Jul · PMID 42300666 · Publisher ↗
Soft electroactive polymer materials are of great interest for soft robotics and biomedical applications because of their large deformability and fast response. Plasticized poly(vinyl chloride) (PVC) gels, particularly P...
Soft electroactive polymer materials are of great interest for soft robotics and biomedical applications because of their large deformability and fast response. Plasticized poly(vinyl chloride) (PVC) gels, particularly PVC/dibutyl adipate (PVC/DBA) gels, exhibit significant bending deformation under relatively low electric fields. In this study, we enhanced the electromechanical response of PVC/DBA gels by adding salts with controlled ion sizes, including ionic liquids and lithium salts. Rheological measurements revealed a critical gelation concentration (PVC weight fraction) of = 0.013 and a fractal dimension of 1.88. At a fixed PVC concentration ( = 0.143) corresponding to a post-gel state, salt addition (5.4 × 10 mol g) increased electrical conductivity by approximately fivefold without significantly affecting elasticity. All gels showed anode-directed bending under an DC electric field, with deformation magnitudes more than five times larger than those of salt-free gels. The most pronounced bending was observed for gels containing a small anion, bis(fluor sulfonyl)imide, and a large cation, 1-ethyl-3-methylimidazolium, which is attributed to asymmetric effective charge densities formed in the electric double layer at the electrodes. These results demonstrate that the ion size control of added salts is an effective strategy for enhancing the electromechanical performance of PVC/DBA gels under low electric fields.
3D morphology and phase-selective transport in amphiphilic silicone hydrogels: experiments and multiscale simulations.
Ito E, Kawagoe Y, Okabe T
Soft Matter · 2026 Jun · PMID 42300639 · Publisher ↗
Amphiphilic bicontinuous nanophase-separated networks can, in principle, provide independent pathways for transporting hydrophobic and hydrophilic species, yet PIPS membranes still lack a tightly validated link between 3...
Amphiphilic bicontinuous nanophase-separated networks can, in principle, provide independent pathways for transporting hydrophobic and hydrophilic species, yet PIPS membranes still lack a tightly validated link between 3D domain connectivity, domain identity, and phase-selective transport. Here, we study amphiphilic silicone hydrogels formed by PIPS from hydrophobic silicone segments and hydrophilic monomers using complementary experiments and multiscale modeling. TEM combined with Fourier analysis resolves nanoscale phase separation, and 3D TEM reconstruction supports a bicontinuous morphology in a representative ternary formulation, providing insight into domain connectivity and composition. To connect structure and function, we measure permeability trends using oxygen as a probe for silicone-rich pathways and sodium ions as a probe for the hydrophilic network, revealing composition-dependent, phase-specific transport. To rationalize morphology formation, key interaction descriptors are extracted from all-atom molecular dynamics and transferred to reactive dissipative particle dynamics simulations of PIPS, yielding domain features consistent with experiments. Finally, domain-restricted random-walk analyses capture the phase-dependent diffusion trends and show that transport selectivity cannot be explained by the domain volume fraction alone; instead, pathway geometry (, tortuosity), which depends on monomer identity, makes a key contribution. Together, these results establish an experiment-simulation workflow linking molecular interactions to 3D morphology and selective transport, enabling the simulation-guided design of amphiphilic membranes.
The cocktail method: influence of microbubble shell homogeneity on acoustic behavior and stability.
Poc P, Guerriero G, Büchler J … +8 more , Grossrieder T, Cattaneo M, Collado-Lara G, Blanken N, Oberhuber I, Kusch J, Supponen O, Schuerle S
Soft Matter · 2026 Jun · PMID 42300627 · Full text
The influence of lipid shell organization on the acoustic behavior of microbubbles (MBs) has become a focal point of ultrasound research. Recent studies have demonstrated that even monodisperse MBs from the same batch ca...
The influence of lipid shell organization on the acoustic behavior of microbubbles (MBs) has become a focal point of ultrasound research. Recent studies have demonstrated that even monodisperse MBs from the same batch can exhibit profoundly different acoustic responses. As high-resolution ultrasound imaging and MB-assisted drug delivery continue to advance, this heterogeneity may compromise performance, causing artifacts and reducing localization accuracy. This study investigates phospholipid organization on the MB surface during both formation and dynamic volumetric changes. Using a panel of membrane probes and labeled lipids in combination with high-resolution confocal microscopy, we characterize lipid surface dynamics, phase behavior, and micro-viscosity. We introduce the 'cocktail method', a straightforward thermal procedure designed to produce seemingly domainless MBs and evaluate how these structural modifications influence acoustic behavior. Our results identify distinct characteristics among individual lipid components during shell formation and provide a qualitative assessment of viscosity within specific lipid phases during expansion and compression. Collectively, these findings reveal that lipid organization impacts shell elasticity and acoustic behavior. Furthermore, we show that the intrinsic physicochemical properties of the lipids DSPC and DSPE-PEG5000 drive an inevitable degree of phase separation that persists despite thermal quenching. This study aims to improve our understanding of the relationship between microbubble lipid architecture and its impact on shell viscoelasticity, stability, and acoustic behavior, ultimately aiding the development of predictable microbubbles for advanced medical applications.
Sequential reaction control during polymerization and formation processes of reactive polyurethane coatings adjusting molecular weight and isocyanate content of the prepolymer.
Zhao B, Xu H, Liu J … +6 more , Zhang J, Duan H, Müller-Buschbaum P, Chen W, Qi D, Zhong Q
Soft Matter · 2026 Jun · PMID 42300583 · Publisher ↗
Sequential reaction control during polymerization and formation processes of reactive polyurethane (RPU) coatings is achieved by adjusting the molecular weight and isocyanate content of the prepolymer. Due to the differ...
Sequential reaction control during polymerization and formation processes of reactive polyurethane (RPU) coatings is achieved by adjusting the molecular weight and isocyanate content of the prepolymer. Due to the different reactivities between the linear chain extender 1,4-butanediol (1,4-BDO) and star-shaped cross-linker 2-ethyl-2-(hydroxymethyl)-1,3-propanediol (TMP), the cross-linking process can be slower than the chain extension, especially under an atmosphere with high viscosity. Thus, by changing the molecular weight () of poly(tetrahydrofuran) (PTMEG) during the preparation of the prepolymer, the viscosity as well as the reaction process can be precisely controlled. When the of PTMEG is 2900 g mol, the obtained mixture presents high viscosity, which enlarges the reactive difference between 1,4-BDO and TMP. Instead of simultaneous reactions, the chain extension and cross-linking are sequentially set. However, when the of PTMEG is reduced to 1000 g mol, the low viscosity causes the difference in reactivity between 1,4-BDO and TMP to be less prominent. The chain extension and cross-linking simultaneously set in, and the three-stage process no longer exists. Similar to the of PTMEG, the isocyanate content of the prepolymer also significantly influences viscosity the external plasticizer effect during the polymerization and formation processes. Thus, by simply adjusting and the isocyanate content of the prepolymer, not only the reactions, but also the structure of RPU coatings can be fine-tuned. The obtained mechanism can be used as the theoretical guidance for controllable polymerization and formation in the PU industry.
Preparation and electrorheological properties of a La-doped MOF-Ti composite encapsulated with TiO.
Pang H, Zhang C, Shan Z … +4 more , Li S, Ma L, Wang B, Hao C
Soft Matter · 2026 Jun · PMID 42300582 · Publisher ↗
Electrorheological fluids (ERFs) are intelligent suspensions capable of rapidly transitioning from liquid-like to solid-like states under an applied electric field. In this work, titanium dioxide-coated, lanthanum-doped...
Electrorheological fluids (ERFs) are intelligent suspensions capable of rapidly transitioning from liquid-like to solid-like states under an applied electric field. In this work, titanium dioxide-coated, lanthanum-doped metal-organic framework (MOF) nanoparticles (La-MOF@TiO) were synthesized a combined solvothermal-hydrolysis method as a high-performance electrorheological (ER) material. The incorporation of lanthanum ions allows precise tuning of the material's dielectric response, and structural stability, while the titania coating forms a tunable core-shell architecture, demonstrating unique potential in ER applications. SEM and TEM analyses, together with elemental mapping, were employed to examine the morphology, microstructure, and component distribution of the samples. Phase composition and chemical states were determined by XRD, FT-IR, and XPS. Nitrogen adsorption-desorption was used to evaluate changes in surface area and pore characteristics, and dielectric spectroscopy was conducted to probe polarization behavior. The ER properties of La-MOF@TiO-based ERFs were assessed using a HAAKE rotational rheometer. A shear-stress plateau of 400 Pa was obtained for MLa-80@TiO nanocomposites at an electric field strength of 3 kV mm and a particle mass fraction of 10 wt%. The results indicate that, compared to solely lanthanum-doped MOF particles, the La-MOF@TiO nanocomposites possess superior electrical properties and excellent ER characteristics.
Modelling the role of interaction heterogeneity in the gelation of micron-scale colloidal systems.
Wu PT, Peng YS, Crocker JC … +1 more , Sinno T
Soft Matter · 2026 Jun · PMID 42300556 · Publisher ↗
Micron-scale colloids functionalized with supramolecular moieties represent a versatile platform for self-assembly. Single-stranded DNA functionalization, in particular, has been shown to be a highly tunable approach for...
Micron-scale colloids functionalized with supramolecular moieties represent a versatile platform for self-assembly. Single-stranded DNA functionalization, in particular, has been shown to be a highly tunable approach for inducing short-ranged attractive interparticle interactions that can be used to drive self-assembly into a wide range of crystalline structures. Recently, it has been noted that variability in the extent of surface functionalization across a population of colloids results in 'interaction heterogeneity', or IH, in which the binding strength between a pair of colloids varies according to the density of DNA strands on their surfaces. We have shown in previous work that IH strongly impacts colloidal crystal nucleation and growth but its impact on gelation further away from equilibrium conditions remains underexplored. In this study, we employ molecular simulations to systematically investigate the role of IH in colloidal gelation driven by thermal quenches. We consider four types of IH distributions: monodisperse (no IH), Gaussian, bidisperse, and uniform distributions, and analyze their effects on gel structure and gelation dynamics. Our results show that while IH minimally impacts macroscopic gel structure, it profoundly alters the local gel environment, as revealed by coordination number (CN) distributions. Principal component analysis of CN moments highlights distinct structural trends arising from the presence of IH, underscoring the sensitivity of local gel structure to IH. We also show that IH leads to a sequential aggregation of strong and weak binders, where strong binders first form a gel 'backbone' and weak binders subsequently decorate it. These findings highlight IH as a key parameter for modulating gel microstructure without significantly perturbing macroscopic organization.
Theoretical modeling and scaling laws in hydrogels incorporating convoluted chain entropy and interchain repulsion.
Li M, Lu H
Soft Matter · 2026 Jun · PMID 42300548 · Publisher ↗
The macroscopic mechanical properties of hydrogels are primarily determined by their microscopic network architecture. However, current micromechanical models typically neglect interchain repulsive interactions, and thei...
The macroscopic mechanical properties of hydrogels are primarily determined by their microscopic network architecture. However, current micromechanical models typically neglect interchain repulsive interactions, and their influence on macroscopic stresses within the network structure remains insufficiently clarified. This study develops a theoretical model that integrates polymer chain conformational entropy with interchain repulsive interactions, establishing scaling laws for model parameters across a range of polymer concentrations. Initially, the polymer reference interaction site model (PRISM) for polymer solutions is utilized to quantify interchain repulsive interactions, which captures the steric repulsion arising between polymer chains. Moreover, the model framework is established by characterizing the crosslinked and entangled chain components within the network structure using the classical eight-chain and tube-constraint framework, where power-law scaling relations are derived for each component. Finally, the proposed model is validated against the reported experimental data, thus providing a robust theoretical framework for the precise design of hydrogel network structures and their mechanical properties.
Elastocapillary lifting and encapsulation of water by a triangular elastic film under gravity.
Shibata K, Kanda H, Tanaka Y … +1 more , Sumino Y
Soft Matter · 2026 Jul · PMID 42300535 · Publisher ↗
We investigate the encapsulation of water by a thin elastic film as a minimal model of elastocapillary self-folding with fluid transport. An equilateral triangular polydimethylsiloxane film is lifted quasi-statically fro...
We investigate the encapsulation of water by a thin elastic film as a minimal model of elastocapillary self-folding with fluid transport. An equilateral triangular polydimethylsiloxane film is lifted quasi-statically from a water surface, while its side length and thickness are systematically varied. Depending on these parameters, the film exhibits three distinct morphologies: folding, recoiling, and liquid encapsulation. We show that the morphology is governed by the interplay of surface, gravitational, and bending energies, and that encapsulation occurs only within a narrow parameter region where the elastocapillary, elastogravity, and capillary length scales become comparable. This provides a simple physical criterion for liquid encapsulation by elastic films.
Theory of hybrid defects, with coupled orientational order parameters, on flat and curved surfaces.
Paik L, Selinger JV
Soft Matter · 2026 Jun · PMID 42300459 · Publisher ↗
Many physical systems involve two types of orientational order, which are coupled together. For example, ferroelectric nematic liquid crystals have coupled polar and nematic order, and tilted hexatic phases have coupled...
Many physical systems involve two types of orientational order, which are coupled together. For example, ferroelectric nematic liquid crystals have coupled polar and nematic order, and tilted hexatic phases have coupled polar and hexatic order. In these systems, defect structures can be quite complex. Here, we investigate phases with two types of two-dimensional orientational order, -atic and -atic, where and are two distinct integers. We simulate these phases in a flat disk with strong radial anchoring, and on a spherical surface, because both of these geometries require the presence of defects. If the coupling between the two types of order is weak, then the defects are connected by a network of diffuse walls, and the system forms a stable domain structure. As the coupling increases, the domain walls become sharper and shorter. For very strong coupling, the higher-order defects merge into the lower-order defects, forming stretched defect cores.
Two-step yielding in a jammed microgel suspension.
Kanheerampockil F, Kurian RM, Bryant G … +1 more , Bhat S
Soft Matter · 2026 Jun · PMID 42300355 · Publisher ↗
We report the mechanism underlying two-step yielding in repulsive colloidal microgel glasses under shear deformation. Strain sweep and start-up flow experiments demonstrate the existence of two-step yielding, which was f...
We report the mechanism underlying two-step yielding in repulsive colloidal microgel glasses under shear deformation. Strain sweep and start-up flow experiments demonstrate the existence of two-step yielding, which was further investigated by creep-recovery, and Lissajous-Bowditch curves to probe intra-cycle nonlinearities. By increasing the microgel volume fraction, we track the transition from entropic to jammed glass regimes and examine the distinct roles of particle softness and crosslinking heterogeneity in yielding behaviour. Soft core-shell particles exhibit two-step yielding in the jammed glass regime at a frequency of = 1 rad s. We compare the results for three types of particles: soft core-shell; stiff core-shell; and homogeneously crosslinked. We find that stiff core-shell and homogeneous particles do not exhibit two-step yielding under any experimental conditions. These findings demonstrate that softness combined with a core-shell particle structure is necessary to support two-step yielding. Intra-cycle nonlinearities reveal that strain stiffening develops between the first and second yield points, arising from resistance to macroscopic flow at and beyond the first ″ peak. This resistance to cage breaking originates from the strong interlocking of interpenetrated polymer chains that occurs during microgel deformation and compression in the jammed state. Macroscopic flow begins at the second yield point, where particles escape their cages by breaking the interlocking structure, leading to the '-″ crossover.
Conformal phase-transition hydrogel interfaces for high fidelity electrophysiological sensing and data-driven inference.
Li X, Tang W, Wang M … +3 more , Moretti G, Lin J, Shi C
Soft Matter · 2026 Jun · PMID 42300257 · Publisher ↗
While gelatin-based conductive hydrogels can acquire electrophysiological signals over multiple days, the statistical consistency and analytical utility of these long-term recordings for data-driven interpretation remain...
While gelatin-based conductive hydrogels can acquire electrophysiological signals over multiple days, the statistical consistency and analytical utility of these long-term recordings for data-driven interpretation remain inadequately assessed. To address this, we developed a gelatin-quaternary ammonium chitosan (GT-QCS) hydrogel electrode that leverages a rapid, temperature-triggered sol-gel transition. Its fluid precursor conforms to complex skin topographies, forming a strongly adhesive interface within two minutes. The ionically crosslinked network shows high stretchability (∼400% strain), tissue-matched modulus (∼73 kPa), strong adhesion (544.1 mN cm), breathability (WVTR ≈ 605 g m day), and low dehydration (∼13% water loss after 30 days). This combination enables stable, week-long acquisition of high-fidelity sEMG, ECG, and EEG signals. The utility of these signals for data-driven analytics was quantitatively validated through a convolutional neural network, which achieved high accuracy in gesture recognition using the long-term sEMG data. Furthermore, the electrode-skin impedance and EEG signal fidelity remained stable over a seven-day period, outperforming standard conductive paste that typically dries within hours. This work demonstrates how phase-transition-enabled hydrogel electrodes can bridge material design with data-driven physiological analysis, offering a general approach for intelligent wearable bioelectronics.
Photo-crosslinked pluronic hydrogels: micelle self-assembly and thermoresponsive behavior.
Habib M, Fragoso J, Joly-Duhamel C … +5 more , Habas JP, Catrouillet S, Tourrette A, Sharkawi T, Blanquer S
Soft Matter · 2026 Jun · PMID 42300214 · Publisher ↗
Amphiphilic block copolymers, such as pluronic triblock copolymers, are widely employed to engineer stimuli-responsive hydrogels for applications ranging from biomedicine to energy and food industries. In this study, we...
Amphiphilic block copolymers, such as pluronic triblock copolymers, are widely employed to engineer stimuli-responsive hydrogels for applications ranging from biomedicine to energy and food industries. In this study, we investigated how the self-assembly temperature of pluronic P123, P104, and F127 affects the crosslinking behavior and the temperature-dependent volume changes of the resulting hydrogels. Each pluronic bearing hydroxyl end-group was functionalized with methacrylic moieties to enable chemical photo-crosslinking and hydrogel formation. Before crosslinking, the impact of chain-end functionalization on micellar organization was evaluated using rheological measurements to map changes in the phase diagrams of the micellar solutions. The results revealed significant shifts in micellar organization for all three pluronics following methacrylation of the hydroxyl groups. Photorheological experiments further demonstrated that the micellar organization directly influenced the kinetics of chemical crosslinking: organized micellar states facilitated faster and more efficient photocrosslinking reactions. Temperature sweeps on the crosslinked systems showed that F127-MA, P123-MA, and P104-MA hydrogels exhibited significantly reduced thermoresponsiveness when crosslinked in an organized state. Finally, the rheologically observed thermal behavior was correlated with the hydrogels' swelling properties. The thermal responses of the pluronic hydrogels resulted in up to 30% water release when crosslinked in an isotropic state, compared to 20% when crosslinked in an organized state. These findings highlight the critical role of micellar organization in tuning the physicochemical properties of pluronic-based hydrogels.
Wetting morphologies and apparent line tension of nanodroplets on soft substrates.
Zhao B, Wang S, Auernhammer GK
Soft Matter · 2026 Jun · PMID 42300208 · Publisher ↗
The size dependence of contact angles for small droplets on solid substrates is typically attributed to line tension. While previous studies have shown that the apparent line tension on rigid substrates is wettability-de...
The size dependence of contact angles for small droplets on solid substrates is typically attributed to line tension. While previous studies have shown that the apparent line tension on rigid substrates is wettability-dependent, the influence of substrate stiffness on line tension for soft, deformable substrates remains elusive. Here, we experimentally demonstrate that the apparent line tension on soft substrates exhibits a clear dependence on substrate stiffness. Using atomic force microscopy to image ionic liquid nanodroplets on polydimethylsiloxane substrates with varying cross-linking densities, we find that the contact angles depend on both the droplet contact radius and the substrate stiffness. Analysis based on the modified Young's equation for soft substrates yields negative apparent line tensions ranging from -5.9 × 10 to -3.5 × 10 J m, in good agreement with theoretical predictions and previous experimental results on rigid substrates. Notably, the absolute value of the apparent line tension decreases on softer substrates, revealing a direct coupling between substrate elasticity and the thermodynamic excess free energy in the three-phase confluence region.
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