Soft Matter最新文献

{"title":"Granular structure and heterogeneous deformation preceding avalanches.","authors":"Ibrahim Awada, Michel Bornert, Vincent Langlois, Julien Léopoldès","doi":"10.1039/d6sm00684a","DOIUrl":"https://doi.org/10.1039/d6sm00684a","url":null,"abstract":"<p><p>Granular packings undergo intermittent rearrangements, known as precursors, before avalanche onset. Using grain-scale tracking in an inclined granular layer, we show experimentally that the number and recurrence of precursors change with the compatibility between the anisotropic structure inherited from preparation and the subsequent loading direction. Preparation also modifies the propagation of the mobility front, defined as the region in which the packing undergoes measurable displacement: frequent precursors produce small progressive advances, whereas rare precursors involve larger extensions. By contrast, several features remain unchanged across protocols. The ensemble-averaged displacement always decays exponentially with depth over approximately four grain diameters, while the local shear-strain variance follows a common quadratic scaling with the mean strain. A two-state model suggests that regardless of the packing structure, local strain heterogeneities affect approximately one quarter of the elementary cells, superimposed on the exponential strain profile. The reported results separate preparation-dependent precursor activity from the robust spatial features of the deformation preceding avalanches.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149101168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Splay and bend elasticity in two-dimensional nematic liquid crystals.","authors":"Peerizah Manav Singh, Debabrata Deb","doi":"10.1039/d6sm00642f","DOIUrl":"https://doi.org/10.1039/d6sm00642f","url":null,"abstract":"<p><p>We present a molecular dynamics simulation study of the Frank orientational elastic constants, namely, splay (<i>K</i>₁) and bend (<i>K</i>₃), in a two-dimensional (2D) thermotropic nematic liquid crystal composed of Gay-Berne ellipses with interaction parameters (3, 5, 2, 1) and aspect ratio 3 : 1. The elastic constants are extracted <i>via</i> the molecular orientation fluctuation method, in which the ensemble-averaged Fourier-transformed orientational order tensor is fitted to a bilinear surface in reciprocal wavevector space within the nematic director frame. A systematic finite-size analysis over five system sizes (<i>N</i> = 10 000 to <i>N</i> = 160 000) identifies <i>N</i> = 160 000 as the optimal system size for convergence toward the thermodynamic limit, with fitting errors below 3.2% for <i>K</i>₁ and below 2.1% for <i>K</i>₃. Both elastic constants decrease monotonically with increasing temperature, reflecting the progressive loss of orientational order as the nematic-to-isotropic transition is approached. Throughout the nematic phase, <i>K</i>₃ > <i>K</i>₁ at all state points, with a bend-to-splay ratio <i>K</i>₃/<i>K</i>₁ ≈ 2 that remains robust across the nematic phase and decreases toward unity only near the transition. The orientational order is further characterized <i>via</i> the orientational correlation function <i>g</i>₂(<i>r</i>), which exhibits algebraic decay <i>g</i>₂(<i>r</i>) ∼ <i>r</i>^{-<i>η</i>₂(<i>T</i>)} throughout the nematic phase, confirming quasi-long-range orientational order consistent with the Mermin-Wagner theorem. The decay exponent <i>η</i>_2,fit(<i>T</i>) increases monotonically with temperature and reaches ≈1/4 at the nematic-to-isotropic transition, consistent with the universal Kosterlitz-Thouless prediction. A comparison with the Nelson-Halperin formula reveals near-quantitative agreement deep in the nematic phase ((<i>T</i>) = <i>η</i>_2,fit/<i>η</i>_2,NH ≈ 0.880-0.870 at <i>T</i> = 0.90-0.95), providing independent validation of the computed elastic constants, while the systematic decrease of (<i>T</i>) toward higher temperatures signals the growing role of critical fluctuations near the transition.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149101363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reference gap technique in viscoelestic sphere impact modeling.","authors":"Xiaoyan Ye, Yingnan Xiu","doi":"10.1039/d6sm00384b","DOIUrl":"10.1039/d6sm00384b","url":null,"abstract":"<p><p>Hydrogel spheres, which undergo large deformations under external force, are widely used in applications ranging from soil conservation to biomedicine, soft robotics, and wearable devices. These large deformations induce strong nonlinearities and emergent phenomena, such as collective granular jamming, which remain difficult to capture within a unified numerical framework. In this study, we propose a discrete-continuous model incorporating a reference gap to construct a continuum hydrogel sphere with tunable Young's modulus. When elastic and surface energies become comparable, surface tension is explicitly incorporated into the model. Then, the relationship between the macroscopic Young's modulus and the microscopic stiffness coefficient is established by quasi-static compression of hydrogel spheres and isotropic compression of rectangular hydrogel blocks. We further evaluate the dynamic behavior of hydrogel spheres with Young's modulus <i>Y</i> ranging from 100 Pa to 50 000 Pa and a Poisson's ratio of 0.5, impacting a rigid substrate at velocities ranging from 0.5 m s^-1 to 4.5 m s^-1, and validate the results against experimental observations. The evolution of morphology and spreading diameter of the superelastic hydrogel spheres, as well as the forces and stresses exerted on spheres, are investigated. The simulation results demonstrate a transition in contact morphology from point contact to Hertzian contact, and eventually to global deformation, accompanied by a corresponding evolution in stress distribution, from point like concentration to single-ring and multi-ring patterns. These phenomena are governed by the propagation of mechanical waves and are characterized by elastic-capillary Mach numbers corresponding to supersonic, critical, subcritical, and highly low subcritical regimes.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" ","pages":"6272-6284"},"PeriodicalIF":2.9,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148928486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geometry-mediated shear softening in dense ordered granular packings.","authors":"Liuchi Li, Konstantinos Karapiperis","doi":"10.1039/d6sm00598e","DOIUrl":"10.1039/d6sm00598e","url":null,"abstract":"<p><p>Shearing a packing of solid granular grains can be difficult, especially when the solid fraction is high and the boundary confinement is strong. It was recently shown that embedding voids in grains can make a packing easier to shear when such voids make the grains auxetic. Here, we use finite element simulation to show that auxeticity is not a necessary condition even in a seemingly very constrained setting: shearing dense and ordered granular packings under a constant solid fraction. More specifically, by changing the geometry-but not the occupied area-of a void embedded in a grain, we are able to induce an apparent elastic anisotropy and softening of the grain under shear, which collectively leads to a significant reduction-up to 90%-of the apparent shear modulus of a packing of these grains. Complementary analysis shows that this reduction correlates well with a decrease in contact-force anisotropy, and is insensitive to system size and contact friction variation. Our results highlight how grain-scale geometry, mediated by multi-body contact mechanics, modulates macroscopic system-scale elasticity, providing a minimal design mechanism towards targeted collective mechanical properties of soft granular metamaterials.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" ","pages":"6362-6369"},"PeriodicalIF":2.9,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148965820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mobile-group dominated dynamics and sequence of mobility transitions in facilitated random walk model of glass.","authors":"Leo S I Lam, Chun-Shing Lee, Hai-Yao Deng, Qiang Zhai, Yunyi Tang, Cho-Tung Yip, Haihui Ruan, Man-Kin Fung, Chi-Hang Lam","doi":"10.1039/d6sm00435k","DOIUrl":"10.1039/d6sm00435k","url":null,"abstract":"<p><p>Glassy dynamics has been a topic of ongoing debate for decades. We investigate a recently proposed facilitated random walk (FRW) model, which is a kinetically constrained model (KCM) with random constraints and is a coarse-grained version of the distinguishable-particle lattice model (DPLM) of glass. Dynamics in the FRW model with a finite density of particles are dominated by mobile groups of particles enjoying emergent facilitated dynamics. We observe a diffusion coefficient power-law with respect to the particle density, with the exponent identified as the dominant mobile group size. In addition, simplified FRW systems initiated with a few particles at the same site exhibit a sequence of mobility transitions, explaining the dynamical dominance of mobile groups. For such systems with two particles, the mobility transition point is calculated exactly.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" ","pages":"6351-6361"},"PeriodicalIF":2.9,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148965860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Weak <i>versus</i> strong polyelectrolyte complexes: two-phase quantification shows chemistry-dependent ion uptake and hydration.","authors":"Giulia Allegri, Jurriaan Huskens, Ricardo P Martinho, Saskia Lindhoud","doi":"10.1039/d6sm00554c","DOIUrl":"https://doi.org/10.1039/d6sm00554c","url":null,"abstract":"<p><p>Designing robust, salt- and pH-responsive polyelectrolyte complex (PEC)-based materials requires controlling the dense-phase composition, including polymer stoichiometry, ion uptake, and hydration, because these parameters ultimately govern mechanics and transport. Yet, these coupled parameters are rarely quantified across coexisting phases, especially under off-stoichiometric mixing. Here, at pH = 6.5 and 250 mM NaCl, we provide a phase-resolved comparison of a weak, charge-regulating system formed by poly(allylamine)/poly(acrylic acid) (PAH/PAA) and a strong, fixed-charge system formed by poly(diallyldimethylammonium)/poly(4-styrenesulfonate) (PDADMAC/PSS). Polymers and ions in both the dense PEC phase and supernatant were quantified using multinuclear NMR (¹H, ²³Na, ³⁵Cl), and bulk hydration was assessed gravimetrically. In both systems, the dense phase converges toward a preferred near-stoichiometric polymer composition, while off-stoichiometry is stored predominantly in the supernatant. Normalized two-phase balances show that most recovered polymer is found in the PEC phase (∼90% for PAH/PAA and ∼80% for PDADMAC/PSS at <i>F</i>^- = 0.5), whereas the large majority of the recovered Na⁺/Cl^- remains in the supernatant and only a small fraction is assigned to the PEC phase. PAH/PAA exhibits a composition-dependent increase in bulk liquid retention at high <i>F</i>^- and supernatant pH shifts consistent with proton exchange, suggesting that proton-coupled charge regulation contributes to charge compensation. In contrast, PDADMAC/PSS shows a small dense-phase ion fraction consistent with fixed-charge polymer pairing. Together, these results provide a transferable phase-composition framework based on stoichiometry, ion partitioning, and bulk hydration, for comparing these two selected PEC chemistries at the same preparation conditions, supporting rational PEC materials design.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149078994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A coarse-grained molecular dynamics study of nanoscale phospholipid-cholesterol vesicles: curvature effects on cholesterol distribution and vesicle structure.","authors":"Zhibo Deng, John M Seddon, Fernando Bresme","doi":"10.1039/d6sm00361c","DOIUrl":"10.1039/d6sm00361c","url":null,"abstract":"<p><p>Nanoscale lipid bilayer vesicles are widely used as model systems for exosomes and synaptic vesicles, released by cells for intercellular communication, in which strong membrane curvature couples molecular packing to asymmetry between the two lipid-bilayer monolayers. Here, we investigate DPPC, POPC or DLiPC phospholipid (PC)/cholesterol bilayer vesicles using coarse-grained molecular dynamics simulations, systematically varying phospholipid chain unsaturation, cholesterol content (0-50 mol%), and vesicle diameter (10-30 nm for the DPPC system). Cholesterol undergoes rapid redistribution on submicrosecond timescales, and is preferentially enriched in the inner leaflet of all vesicles studied, with the degree of asymmetry depending on the vesicle curvature, cholesterol content and PC chain saturation. Increasing cholesterol content induces bilayer thickening, reduced area per lipid and enhanced chain ordering. Highly curved vesicles are thinner than planar bilayers. These effects depend strongly on PC unsaturation and vesicle size, highlighting the synergistic role of these variables in controlling membrane structure and cholesterol partitioning in nanoscale vesicles.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" ","pages":"6238-6249"},"PeriodicalIF":2.9,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148910155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synthesis of flat, skateboard colloidal particles with triaxial asymmetry using the film deformation method.","authors":"Lakshmi Savitha Tanikella, Mahesh Ganesan","doi":"10.1039/d6sm00622a","DOIUrl":"10.1039/d6sm00622a","url":null,"abstract":"<p><p>We produce prolate ellipsoidal polymeric colloids with triaxial asymmetry, resembling the shape of a skateboard. The particles are characterized by unequal polar and equatorial semiaxes and are produced by a simple modification to the film squeezing method, which conventionally yields only biaxially symmetric spheroids. These particles contribute to the growing library of shape anisometric polymer colloids and given their unequal principal axes, they could serve as interesting building blocks for designing colloidal systems such as crystals, gels and active suspensions.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" ","pages":"6191-6197"},"PeriodicalIF":2.9,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148987168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Viscoelastic solutions formed from resveratrol-based trimeric anionic surfactants.","authors":"Yanling Zheng, Shilian Fu, Xiaomei Pei, Zhao Chen, Binglei Song, Zhenggang Cui, Danhua Xie","doi":"10.1039/d6sm00795c","DOIUrl":"10.1039/d6sm00795c","url":null,"abstract":"<p><p>Achieving high viscoelasticity in additive-free anionic surfactant systems remains a significant challenge. Herein, taking the natural product resveratrol as the starting material, a series of resveratrol-based star-type trimeric anionic surfactants (Res-trisC_<i>n</i>Na, <i>n</i> = 14, 16, 18) were designed and synthesized. These surfactants exhibit ultra-low critical micelle concentrations (CMCs < 0.01 mM), approximately three orders of magnitude lower than those of conventional single-chain counterparts. Notably, these surfactants form highly viscoelastic solutions without any additives at relatively low concentrations-a behavior rarely observed in single-component anionic surfactant systems. Res-trisC₁₆Na exhibits the best rheological performance, achieving a zero-shear viscosity of 1671.2 Pa s and a relaxation time of 41.67 s at 80 mM. Cryo-TEM and SAXS analyses confirmed the formation of flexible wormlike micelles. The remarkable viscoelasticity is attributed to the long, rigid stilbene spacer, which restricts the spatial proximity of the hydrophobic chains within individual molecules and produces a pseudo-volume, thereby favoring one-dimensional micellar growth. These findings demonstrate that long, rigid spacers are effective design elements in oligomeric surfactants forming viscoelastic solutions and provide a new route for the high-value utilization of natural products.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" ","pages":"6343-6350"},"PeriodicalIF":2.9,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148965850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ordering in confined two-dimensional nematic systems: mesoscopic simulations based on different mean-field potentials.","authors":"Humberto Híjar, Apala Majumdar","doi":"10.1039/d6sm00110f","DOIUrl":"10.1039/d6sm00110f","url":null,"abstract":"<p><p>We use nematic Multi-particle Collision Dynamics (N-MPCD) simulations to study confined nematic liquid crystals in square domains, with three distinct mean-field potentials: the classical Maier-Saupe and Marrucci-Greco models, and a more recent model due to Ilg, Karlin, and Öttinger. These potentials incorporate diverse physical features, including spatial gradients and nonlinear dependencies on the order parameter, to describe nematic ordering at mesoscopic scales. We derive coarse-grained equations from a Fokker-Planck description with tensorial closures, and analyse the emergence of order as a function of interaction strength, <i>U</i>, in two dimensions (2D). We estimate the critical interaction strength for the onset of nematic ordering (also interpreted as the isotropic-nematic transition in 2D) and the nematic coherence length in 2D, for the three different mean-field models. This enables a rigorous correspondence between the N-MPCD parameters (the system size <i>R</i> and <i>U</i>) and the continuum Landau-de Gennes theoretical parameters. We systematically study equilibrium and metastable configurations, including relaxation pathways to stable equilibria, on square domains with tangent boundary conditions, for all three mean-field potentials. Our results confirm universal equilibrium and metastable configurations for all three mean-field potentials. Our results also suggest that the N-MPCD predictions are consistent with the continuum Landau-de Gennes predictions, regardless of the choice of the underlying mean-field potential and approximations, for large <i>R</i> and large <i>U</i>.</p>","PeriodicalId":103,"journal":{"name":"Soft Matter","volume":" ","pages":"6304-6322"},"PeriodicalIF":2.9,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148962728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}