Soft Matter[JOURNAL]
Sun
200 papers
Coupling of electrospinning and photo-induced processes for advanced nanofibrous polymeric materials: current state-of-the-art and future perspectives.
Vu TN, Vitale A
Soft Matter · 2026 May · PMID 41954372 · Publisher ↗
Electrospinning is a versatile and widely adopted technique for the fabrication of nanofibrous polymeric materials with high surface area, interconnected porosity, and tunable architectures. However, conventional electro...
Electrospinning is a versatile and widely adopted technique for the fabrication of nanofibrous polymeric materials with high surface area, interconnected porosity, and tunable architectures. However, conventional electrospun mats often suffer from limited mechanical robustness, poor resistance to water or solvents, and restricted control over functionality, which hampers their deployment in advanced applications. In recent years, the integration of electrospinning with photo-induced processes has emerged as a powerful strategy to overcome these limitations by enabling controlled polymerization, crosslinking, and surface functionalization under mild and spatially selective conditions. This review provides a comprehensive overview of the current state of the art in coupling electrospinning with photo-induced reactions for the design of advanced nanofibrous polymeric materials. Both photopolymerization during fiber formation and post-spinning photo-induced crosslinking or grafting are discussed, with emphasis on the underlying chemistries, including free-radical (meth)acrylate systems, thiol-ene click reactions, photocycloaddition-based processes, and cationic photopolymerization. Representative examples spanning low-molecular-weight precursors, macromers, polymers, and hybrid organic-inorganic systems are critically analyzed to highlight structure-property-function relationships and processing-reactivity interplay. Beyond summarizing recent advances, this review outlines key challenges and future perspectives, including reaction-jet coupling, scalability, sustainability, and the development of dynamic and multifunctional fibrous systems. By framing electrospinning as a reactive manufacturing platform enabled by photochemistry, this work aims to guide future research toward the rational design and translation of next-generation nanofibrous materials for biomedical, environmental, energy, and smart-material applications.
Disentangling microstructural elements of shear thickening suspensions computer simulations of a minimal model.
Buchholtz WCJ, Blair DL, Urbach JS … +2 more , Vinutha HA, Del Gado E
Soft Matter · 2026 May · PMID 41954138 · Publisher ↗
We use a minimal model for a dense suspension undergoing thickening and thinning to investigate microstructural changes in 2d simulations. Our simulations show that in steady flow the contact network contains distinct bu...
We use a minimal model for a dense suspension undergoing thickening and thinning to investigate microstructural changes in 2d simulations. Our simulations show that in steady flow the contact network contains distinct building blocks which are clearly signaled by sharp peaks in the radial distribution function, similar to what is observed in granular jamming. These structures deform during thinning. Non-Gaussian stress fluctuations that only emerge during thickening are associated to power law tails in the distribution of local contact forces, which tend to emerge when the flow-induced building blocks form large spanning assemblies. The subset of the contact network characterized by strong contact forces and connectivity large enough to be rigid or over-constrained is increasingly likely to percolate as the system starts to thicken, and to percolate over larger strain windows during thickening. The tendency of these structures to span the sample and to persist is dramatically reduced during thinning, where instead their deformation allows for a more homogeneous spatial redistribution of contact forces, significantly reducing the fluctuations of the macroscopic stress over time.
Kinetic theory of dilute weakly charged granular gases with hard-core and inverse power-law interactions under uniform shear flow.
Kobayashi Y, Kikuchi MR, Iizuka S … +1 more , Takada S
Eur Phys J E Soft Matter · 2026 Apr · PMID 41952017 · Publisher ↗
We develop a kinetic-theory framework to investigate the steady rheology of a dilute gas interacting via a repulsive potential under uniform shear flow. Starting from the Boltzmann equation with a restitution coefficient...
We develop a kinetic-theory framework to investigate the steady rheology of a dilute gas interacting via a repulsive potential under uniform shear flow. Starting from the Boltzmann equation with a restitution coefficient that depends on the impact velocity and potential strength, we derive evolution equations for the stress tensor based on Grad's moment expansion. The resulting expressions for the collisional rates and transport coefficients are fitted with simple analytical functions that capture their temperature dependence over a wide range of shear rates. Comparison with direct simulation Monte Carlo (DSMC) results shows excellent quantitative agreement for the shear stress, temperature anisotropy, and shear viscosity. We also analyze the velocity distribution functions, revealing that the system remains nearly Maxwellian even under strong shear.
Recyclable flexible sensors based on digital-light-processing 3D printing of a thermoplastic elastomer and facile transfer of pencil-marked graphite films.
Wang L, Liu M, Guo D … +6 more , Jin F, Bi C, Zhang H, Jiang L, Chen S, Xiong Z
Soft Matter · 2026 Apr · PMID 41949081 · Publisher ↗
Light-based 3D printing has revolutionized the development of flexible strain sensors by enabling the customizable fabrication of geometrically complex structures with high precision. A recyclable elastomer substrate for...
Light-based 3D printing has revolutionized the development of flexible strain sensors by enabling the customizable fabrication of geometrically complex structures with high precision. A recyclable elastomer substrate for strain sensors based on photocuring 3D printing is highly desirable from ecological and economic perspectives. However, it is hard to achieve both printability and recyclability simultaneously since crosslinked polymer networks are difficult to reprocess. In this study, in order to recycle the digital-light-processing (DLP)-3D-printed sensor elastomer, a design strategy for fabricating stretchable strain sensors was proposed by combining direct DLP-3D-printing of a thermoplastic poly(isodecyl acrylate)(PIDA)/poly(styrene--ethylene-butylene--styrene)(SEBS) elastomer and transferring a conductive layer of pencil-marked graphite films onto it. The photoresin for printing was prepared by dissolving commercial thermoplastic elastomer SEBS in monomer IDA without any crosslinker. Attributed to the linear polymer molecular structure and the good mechanical properties of SEBS, the photocured elastomer showed good thermoplasticity and elasticity. The PIDA/SEBS sensor has a wide sensing range (strain: 0-280%) with high sensitivity (gauge factor: 9355). The 3D printed finger sleeve sensor can monitor the movement of finger bending precisely. By erasing the conductive pencil marks, the PIDA/SEBS elastomer can be remolded to prepare a new strain sensor.
Glass transition and subphase anchoring govern the emergence of viscoelasticity in polymer interfaces.
Ashkenazi D, Alexandris S, Vermant J … +2 more , Vlassopoulos D, Gottlieb M
Soft Matter · 2026 Apr · PMID 41947755 · Publisher ↗
Determining the rheological properties and the interfacial structure-property relationships for complex fluid-fluid interfaces is crucial for understanding physiological systems, and for designing and engineering industr...
Determining the rheological properties and the interfacial structure-property relationships for complex fluid-fluid interfaces is crucial for understanding physiological systems, and for designing and engineering industrial processes. While it is well established that polymer-laden interfaces can exhibit viscoelastic properties, the relationship between polymer molecular characteristics and interfacial mechanical response remains insufficiently understood. In this work, we investigate the role of two fundamental polymer properties: dynamic flexibility as manifested by the glass transition temperature () and anchoring strength to the water subphase. We examine the relative importance of these two properties as they govern interfacial morphology and rheology. To this end, we systematically study six homopolymers - poly(dimethylsiloxane), poly(-butyl acrylate), poly(methyl methacrylate), poly(-butyl methacrylate), poly(4-vinylphenol), and polystyrene, that span a range of values and water subphase interaction strengths. Their interfacial behavior is characterized by Langmuir-Pockels trough isotherms, interfacial shear rheology, Brewster angle microscopy (BAM), and neutron reflectivity. Film thickness and homogeneity are evaluated. Our findings show two distinct interfacial regimes: polymers with below room temperature exhibit a morphology composed of discrete globular domains. Quantitative analysis of film thickness shows large interfacial heterogeneity. Their Langmuir isotherms are fully reversible, showing no hysteresis nor relaxation upon compression. Interfacial rheology measurements yield no detectable shear moduli. In contrast, high- polymers form 1-2 nm thick continuous interfacial films. Their isotherms display pronounced hysteresis, significant relaxation at high compression, and no recovery after the first compression. They exhibit measurable viscoelastic moduli, even at moderate surface concentrations below full coverage of the interface. Polystyrene, with no interfacial affinity, fails to form an interfacial film and thus produces inconsistent rheological footprint. Taken together, these results establish that the formation of a viscoelastic polymer interface requires both a glass transition temperature exceeding the operating temperature and some minimal level of interaction with the aqueous subphase.
Non-local rheology in granular media: a perspective on the 2015 EPJE Paper by Bouzid et al.
Pouliquen O
Eur Phys J E Soft Matter · 2026 Apr · PMID 41945266 · Publisher ↗
The study "Non-local rheology in dense granular flows: Revisiting the concept of fluidity," published in 2015 in The European Physical Journal E (vol. 38) by Mehdi Bouzid and collaborators, stands as an important contrib...
The study "Non-local rheology in dense granular flows: Revisiting the concept of fluidity," published in 2015 in The European Physical Journal E (vol. 38) by Mehdi Bouzid and collaborators, stands as an important contribution to the rheology of granular materials. In their work, the authors critically discuss the differences between proposed non-local models and provide clear pathways to discriminate between them. This perspective paper revisits the state of the art at the time of the Bouzid et al's publication, highlighting its role in inspiring subsequent research. We then explore recent advancements since 2015, which, while significant, have not yet fully resolve the questions originally raised by Bouzid et al.
Glassy dynamics and nanoconfinement: what we learned, what comes next.
Napolitano S
Eur Phys J E Soft Matter · 2026 Apr · PMID 41944979 · Publisher ↗
Over the past three decades, spatial confinement has reshaped our understanding of polymers as glass-forming materials. Rather than merely perturbing bulk behavior, geometric and interfacial constraints introduce new len...
Over the past three decades, spatial confinement has reshaped our understanding of polymers as glass-forming materials. Rather than merely perturbing bulk behavior, geometric and interfacial constraints introduce new length and time scales that actively transform materials response, underpinning a range of otherwise distinct phenomena, from microscopic dynamics and macroscopic relaxation to vitrification and mechanical properties. By reducing at least one system dimension to the nanoscale, combined experimental, theoretical, and simulation efforts have revealed how confinement selects which dynamic modes remain active, uncovering relaxation pathways that might be silent in the bulk. These convergent insights have matured into a robust conceptual framework, which continues to evolve as new questions emerge. This perspective focuses on three themes that I consider central to this evolution: the decoupling of thermal and dynamical signatures of the glass transition under confinement, the emergence of finite low-frequency rigidity in confined liquids and soft solids, and the stabilization of long-lived nonequilibrium states mediated by interfaces and reduced dimensionality. The discussion of these topics points toward a necessary evolution: further progress will require theories that move beyond equilibrium descriptions to explicitly incorporate nonequilibrium pathways and emergent microscopic routes to macroscopic relaxation, ultimately bridging the gap toward a more complete, predictive description of glassy polymer dynamics.
Interfacial adsorption competing with thermal mixing in confined hydrogen-bonded polymer bilayers.
Tetsutani H, Ohno M, Nakanishi Y … +6 more , Miyazaki T, Takenaka M, Yamada NL, Seto H, Aoki H, Yamamoto K
Soft Matter · 2026 May · PMID 41944806 · Publisher ↗
In confined polymer thin films, interfacial chain adsorption can fundamentally compete with thermally driven interdiffusion, leading to mixing behavior distinct from bulk systems. Here, we investigated ultrathin hydrogen...
In confined polymer thin films, interfacial chain adsorption can fundamentally compete with thermally driven interdiffusion, leading to mixing behavior distinct from bulk systems. Here, we investigated ultrathin hydrogen-bonded PMMA/PVPh bilayers on silicon substrates using complementary X-ray reflectivity, neutron reflectivity, and near-edge X-ray absorption fine structure spectroscopy. Thermal annealing induced progressive interdiffusion and eventual miscibility across the bilayer. However, even after apparent homogenization, a nanometer-thick PVPh-rich layer persisted at the substrate interface and remained resistant to dissolution in a good solvent. Neutron scattering length density profiles revealed that this low-SLD interfacial region survived at elevated temperatures, while surface-sensitive spectroscopy confirmed preferential enrichment and strongly stabilized adsorption of PVPh chains at the oxide interface. These findings demonstrate that strong polymer-substrate interactions can arrest complete interfacial homogenization under confinement, generating asymmetric composition profiles despite bulk miscibility. The results highlight the fundamental role of surface-induced stabilization of adsorbed chains in governing mixing and structural evolution in ultrathin polymer films.
Rational design of amphiphilic pyrrolidinium derivatives: structure-activity correlation and alkyl chain tuning for superior antimicrobial activity.
Vasilieva EA, Kuznetsova DA, Babkin RA … +5 more , Kuznetsov DM, Lubina AP, Voloshina AD, Valeeva DN, Zakharova LY
Soft Matter · 2026 Apr · PMID 41944565 · Publisher ↗
A novel amphiphilic pyrrolidine derivatives, 1-alkyl-1-(2-(hexyl carbamoyloxy)ethyl)pyrrolidinium bromides (CPS--6, where = 12, 14, 16, and 18), were synthesized and characterized. Comprehensive investigations demonstra...
A novel amphiphilic pyrrolidine derivatives, 1-alkyl-1-(2-(hexyl carbamoyloxy)ethyl)pyrrolidinium bromides (CPS--6, where = 12, 14, 16, and 18), were synthesized and characterized. Comprehensive investigations demonstrated that the amphiphiles synthesized exhibit multifunctional properties and meet stringent biomedical criteria. CPS--6 possess membranotropic activity and are capable of forming mixed lipid/surfactant bilayers, imparting a positive surface charge and stabilizing biological membranes. Surfactant-based supramolecular systems exhibit the properties of micellar nanocontainers, demonstrate enhanced solubilization capacity toward hydrophobic probe Orange OT and antibiotic amphotericin B, and are characterized by nanoscale dimensions of 2-10 nm along with a high positive zeta potential of up to +89 mV. Encapsulation of amphotericin B into CPS--6 results in a significant enhancement of its antifungal activity against . The amphiphiles also exhibit high antimicrobial activity against both Gram-positive and Gram-negative bacteria, including methicillin resistant strains. The most pronounced effect was observed for the dodecyl and tetradecyl homologues, which significantly surpassed the activity of amoxicillin and ciprofloxacin. Investigation of the mechanisms of antimicrobial action revealed that CPS--6 do not disrupt the cell wall of at the MIC and MBC; however, they impair cytoplasmic membrane permeability and induce membrane depolarization, particularly in the case of CPS-12-6. The amphiphiles demonstrated moderate hemotoxicity (HC = 37-50 µM), which showed a weak dependence on the alkyl tail length. CPS-14-6 exhibited the highest selectivity against (SI = 39), whereas CPS-18-6 was markedly less selective (SI = 2), indicating a higher risk of hemolysis at a comparable MIC.
Excitability induced binary interactions in self-propelled Belousov-Zhabotinsky droplets.
Meshram VB, Shajahan TK
Soft Matter · 2026 Apr · PMID 41944024 · Publisher ↗
The Belousov-Zhabotinsky (BZ) reaction is an example of a nonlinear chemical oscillator, where the reagents undergo successive oxidation and reduction over a period of time. When a droplet containing the BZ reaction is p...
The Belousov-Zhabotinsky (BZ) reaction is an example of a nonlinear chemical oscillator, where the reagents undergo successive oxidation and reduction over a period of time. When a droplet containing the BZ reaction is placed in an oily medium, it can move without external force. This self-propelled motion of the BZ droplet is caused by the chemical oscillation inside the BZ droplet and the Marangoni effect at its boundary. In this experimental work, we explore the interaction of the BZ droplet as a function of excitability (sodium bromate). We find that the frequency of oscillations, the speed of the BZ droplet, and changes in the direction of motion increase as a function of sodium bromate. When there are multiple droplets, the interaction time between droplets decreases with sodium bromate. We also analysed the interaction of the two droplets when their volumes are different. We observed three types of interactions: the droplets can approach head-on, they move along parallel paths, or the big droplet follows the smaller droplet. The interaction time is maximum when the big droplet follows the small droplet. These findings offer insights into controlling and understanding emergent phenomena in active matter systems.
Inference of the 3D pressure field exerted by a single cell from a thin membrane transverse deformation.
Bédel Q, Dupré L, Destainville N
Eur Phys J E Soft Matter · 2026 Apr · PMID 41942677 · Full text
Numerous cell types relate to their immediate environment by exerting a three-dimensional pressure field on their environment, with components both longitudinal and transverse to the cell membrane. This pressure field ca...
Numerous cell types relate to their immediate environment by exerting a three-dimensional pressure field on their environment, with components both longitudinal and transverse to the cell membrane. This pressure field can in principle be measured by traction force microscopy experiments. Compared to other approaches, the technique of protrusion force microscopy gives access with high spatial resolution to the pressure field by measuring the deformation of a thin elastic membrane using atomic force microscopy (AFM). However, while the pressure field under interest is three-dimensional, the height profile measured by AFM is only one-dimensional. We propose a solution to this inverse problem and we explore its regime of applicability in the experimental context.
Formation of cylindrical shells via sphere packing from fluidized beds.
Oliveira VPS, Borges DS, Franklin EM … +1 more , Peixinho J
Eur Phys J E Soft Matter · 2026 Apr · PMID 41931265 · Full text
The results of a numerical investigation of fluidized beds of spherical particles in a narrow vertical cylindrical pipe, with particular attention to the spontaneous settling along the wall, are reported. Starting from a...
The results of a numerical investigation of fluidized beds of spherical particles in a narrow vertical cylindrical pipe, with particular attention to the spontaneous settling along the wall, are reported. Starting from a steady fluidized state, the particles fluctuate because of fluid-particle, particle-particle, and particle-wall interactions. The particles are heavier than the fluid, with diameters d yielding ratios of pipe to particle diameters and 4.7. For given ranges of flow velocities and bed sizes, particles settle on the wall, with a decrease in the bed height and particle fluctuations. Either a glass- or crystal-like shell forms along the pipe wall, in qualitative agreement with previous experiments. The polydispersity and the particle-particle friction are varied to test the stability of the particulate shell formation. The shell structure is analyzed by unwrapping it in a plane and locating all particles and their contact points, and we find that it exhibits a hexagonal lattice with a defects density that increases with polydispersity. The shell formation is hindered by polydispersity, and there exists a critical point for polydispersity above which a crystal-like shell is unstable. In a particular case of bidisperse beds, the crystal-like shell only appears when the particle-particle friction is high enough. Finally, we compute the contact forces within particle-particle chains and in particle-wall contacts, which sustain the cylindrical shell, highlighting the dominant role of particle-particle forces.
Perspective on "Active Brownian particles moving in a random Lorentz gas".
Reichhardt C, Reichhardt CJO
Eur Phys J E Soft Matter · 2026 Apr · PMID 41925789 · Full text
Self-propelled active matter can exhibit vastly different behavior than systems with purely Brownian motion. In Eur. Phys. J. E 40, 23 (2017), Zeitz, Wolf, and Stark compared an active matter particle with a Brownian par...
Self-propelled active matter can exhibit vastly different behavior than systems with purely Brownian motion. In Eur. Phys. J. E 40, 23 (2017), Zeitz, Wolf, and Stark compared an active matter particle with a Brownian particle moving in a random obstacle array. They showed that near the obstacle percolation density, both Brownian and active particles exhibit the same subdiffusive behavior, but the active particle reaches a steady state more rapidly. They also found that for high activity, the active particle has a lower effective diffusion than the Brownian particle due to the increased self-trapping effect generated by the activity. This result opens new directions for the study of active matter in disordered media, including bacteria in porous media, active colloids on quenched disorder, and active particles in crowded environments.
Morphological changes in smectic liquid crystal microstructures.
Sato D, Sumino Y, Yamamoto T … +2 more , Muševič I, Takenaka Y
Soft Matter · 2026 May · PMID 41925320 · Full text
We report temperature-induced morphological transitions of smectic liquid crystal (LC) microstructures from fibers to disc- and umbrella-like structures. We used two systems based on 4-cyano-4'--octyloxybiphenyl (8OCB):...
We report temperature-induced morphological transitions of smectic liquid crystal (LC) microstructures from fibers to disc- and umbrella-like structures. We used two systems based on 4-cyano-4'--octyloxybiphenyl (8OCB): an 8OCB/decanol system and an 8OCB/cetyltrimethylammonium bromide (CTAB) system. In both systems, LC fiber structures grew from the droplets upon cooling. The LC fiber structures in both systems underwent similar morphological transitions into umbrella-like structures an intermediate disc-like structure. Furthermore, we observed that repeated temperature cycling induced reversible morphological transitions between umbrella- and disc-like structures. We developed a simple free-energy model, based on elastic and topological defect energies, that explains these morphological changes. These findings suggest design principles for stimuli-responsive smectic LC microstructures and may provide physical insight into the deformation of phase-separated, membraneless organelles.
Coupling of colloidal rods to the dynamic order of active nematic films.
Rivas DP, Head LC, Berret JF … +3 more , Shendruk TN, Reich DH, Leheny RL
Soft Matter · 2026 Apr · PMID 41924865 · Full text
We report the dynamics of active nematic films and the hydrodynamic forces they generate measurements on micrometer-scale magnetic rods positioned in close proximity to the films. In the absence of an external magnetic...
We report the dynamics of active nematic films and the hydrodynamic forces they generate measurements on micrometer-scale magnetic rods positioned in close proximity to the films. In the absence of an external magnetic field, the rods translate with the flow of the film, and the long axes of the rods maintain parallel alignment with the film's local nematic director, even though the rods are not in direct contact with the film. The rods' translational and orientational dynamics are hydrodynamically coupled to the velocity field and its gradients in the active film. This alignment and translation facilitate measurement of correlations of the nematic director in the frame of reference of the active flow, which display a periodicity that is not present in the correlation function calculated at a fixed point in space. We identify hydrodynamic torques as the source of the rods' alignment with the time-varying local director. By applying magnetic torques external fields to rotate the rods out of alignment with the director, we characterize their relaxation back toward alignment and thereby quantify the hydrodynamic torques imposed on the rods. These measurements provide insight into the flow-aligning hydrodynamic properties of active nematic films, which are thought to play a fundamental role in the nematic order.
Dynamical networking of polymer networks with dedicated cross-linker particles.
du Toit N, Müller-Nedebock KK, Pellicane G
Eur Phys J E Soft Matter · 2026 Apr · PMID 41922872 · Full text
This paper extends a field-theoretical dynamical networking formalism for mesoscopic polymer dynamics to explicitly include dedicated cross-linker particles. Cross-linkers are represented within a Martin-Siggia-Rose gene...
This paper extends a field-theoretical dynamical networking formalism for mesoscopic polymer dynamics to explicitly include dedicated cross-linker particles. Cross-linkers are represented within a Martin-Siggia-Rose generating functional and reversibly coupled to polymers through Gaussian networking fields, enabling an approximation scheme that reduces their degrees of freedom while remaining compatible with polymer dynamics. The framework is applied to a two-species polymer system in which intra- and inter-species cross-linking are assigned different statistical advantages. Effective networking potentials are derived and used to calculate correlation functions and dynamic structure factors. To validate these results, molecular dynamics simulations of semi-flexible polymers with reversible intra- and inter-species cross-linking are performed. Simulations show that cross-linking decreases polymer persistence lengths and local alignment, and the resulting trajectories yield dynamic structure factors consistent with theoretical predictions. Qualitative comparison reveals that in both approaches, cross-linking broadens the diffusive peaks and enhances the high-frequency tails of the structure factors. Together, theory and simulation provide complementary insights into the dynamics of cross-linked polymers, establishing a tractable framework that captures essential features observed in experiments and offering a basis for exploring more complex synthetic and biological networks.
Hyperuniformity in ternary fluid mixtures: the role of wetting and hydrodynamics.
Padhan NB, Voigt A
Soft Matter · 2026 Apr · PMID 41920008 · Publisher ↗
Phase separation in multicomponent fluids is central to understanding the organization of complex materials and biological structures. The multicomponent Cahn-Hilliard-Navier-Stokes (CHNS) equations offer a robust framew...
Phase separation in multicomponent fluids is central to understanding the organization of complex materials and biological structures. The multicomponent Cahn-Hilliard-Navier-Stokes (CHNS) equations offer a robust framework for modeling such systems, capturing both diffusive dynamics and hydrodynamic interactions. In this work, we investigate hyperuniformity-characterized by suppressed large-scale density fluctuations-in ternary fluid mixtures. These serve as prototypical example of multicomponent fluids and are governed by the ternary CHNS equations. Using large-scale direct numerical simulations in two dimensions, we systematically explore the influence of wetting conditions and hydrodynamic effects on emergent hyperuniformity. Similar to binary systems we observe that the presence of hydrodynamics weakens the hyperuniform characteristics. However, also the wetting properties have an effect. We find that in partial wetting regimes, all three components exhibit comparable degrees of hyperuniformity. In contrast, for complete wetting scenarios, where one component preferentially wets the other two, the wetting component displays a significant reduction in hyperuniformity relative to the others. These findings suggest that wetting asymmetry can act as a control parameter for spatial order in multicomponent fluids.
Modeling tumor transport and growth with poroelastic biopolymer networks.
Li Z, Ren Y, Kemkar S … +6 more , Mollenkopf P, Kochanowski J, Janmey PA, Purohit PK, Radhakrishnan R, Vining KH
Soft Matter · 2026 Apr · PMID 41919661 · Full text
The mechanical properties of the extracellular matrix (ECM) regulate tumor growth and invasion in the tumor microenvironment. Models of biopolymer networks have been used to investigate the impact of elasticity and visco...
The mechanical properties of the extracellular matrix (ECM) regulate tumor growth and invasion in the tumor microenvironment. Models of biopolymer networks have been used to investigate the impact of elasticity and viscoelasticity of the ECM on tumor behavior. Under tumor compression, these networks also show poroelastic behavior that is governed by the resistance to water flow through their pores. This work investigates the hypothesis that stress-dependent transport properties of biopolymer networks regulate tumor growth. Here, alginate hydrogels are used as a model ECM system with tunable ionic and hybrid ionic/covalent crosslinking. Hydrogel stiffness, viscoelasticity, and stress relaxation behavior were characterized using stepwise axial compression. Among these properties, we find poroelastic fluid outflow dominates ECM stress relaxation, as the measured water flux was significantly affected under compression. Continuum mechanics-based modeling was developed to formulate and calculate the chemical potential gradients of water (solvent) in the hydrogels under compression. This framework was extended into an advection-diffusion framework to quantify growth factor (solute) distribution under varying strengths of stress and diffusion indexed by the relative strength of convective to diffusive transport, characterized by the Péclet number. An agent-based computational simulation showed that the Péclet numbers based on our experimental timescales strongly influenced tumor growth over longer, more physiologic timescales. Together, these results highlight the important role of water flux and transport in three-dimensional biopolymer networks.
Activated solids: spontaneous deformations, non-affine fluctuations, softening, and failure.
Nath P, Das D, Sengupta S … +1 more , Chaudhuri D
Soft Matter · 2026 Apr · PMID 41919597 · Publisher ↗
Internal activity can fundamentally reshape the mechanical behavior of solids, yet its role in softening and failure remains incompletely understood. In this study, we investigate spontaneous deformations in activated so...
Internal activity can fundamentally reshape the mechanical behavior of solids, yet its role in softening and failure remains incompletely understood. In this study, we investigate spontaneous deformations in activated solids non-affine fluctuations that quantify local rearrangements relative to global strain. Using scaling analysis and numerical simulations, we show that non-affinity in crystalline solids grows quadratically with active speed and increases linearly with persistence time before saturating. Spatial correlations reveal an activity-dependent growing correlation length, while relaxation dynamics are governed by the active persistence time. With increasing activity, the distributions of local non-affinity broaden, become more skewed, and develop heavy tails, eventually forming a secondary maximum that signals coexisting small and large non-affinities; this heterogeneity precedes defect formation and two-step melting from solid to hexatic and ultimately to fluid. Finally, we demonstrate that spatially patterned activation provides a simple route to locally induce non-affinity and mechanical softening. Our predictions are experimentally testable and suggest a pathway to tunable mechanics in adaptive metamaterials, with implications for mechanical regulation in biological systems.
Symmetry breaking of interacting charge-regulated planar macroions at low salt concentration.
Itani AMN, Bossa GV, Hossain F … +1 more , May S
Soft Matter · 2026 Apr · PMID 41919562 · Publisher ↗
The charge of macroions such as colloids and membranes can often be regulated by reversible ion adsorption or dissociation reactions. When two chemically identical macroions interact across an electrolyte, charge regulat...
The charge of macroions such as colloids and membranes can often be regulated by reversible ion adsorption or dissociation reactions. When two chemically identical macroions interact across an electrolyte, charge regulation will typically lead to the same charge density on both macroion surfaces. However, it was recently demonstrated that a non-ideal, Frumkin-like adsorption behavior of the ions can lead to a spontaneous symmetry breaking, where the coupling of charge regulation leads to different surface charge densities on both macroions in thermal equilibrium. While previous modeling was carried out numerically in the presence of salt for selected systems, we argue that the no-salt limit captures experimentally relevant situations at low salt concentration. We therefore focus on macroions with dissociable surface groups in the absence of salt, where the Poisson-Boltzmann equation can be solved analytically and the spontaneous emergence of uniform but different degrees of dissociation on both macroions signifies a symmetry breaking. Using a perturbation approach we derive analytic results for the local stability of the symmetric state. This not only provides a complete thermodynamic characterization of the symmetry breaking as function of all parameters, it also uncovers previously unrecognized features. First, depending on the degree of non-ideality, the symmetry breaking transition can be continuous or discontinuous. Second, metastable states do exist far away from critical points but not in their vicinity. And third, electrostatic interactions generally act toward weakening or suppressing the occurrence of symmetry breaking.
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