Soft Matter[JOURNAL]
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200 papers
Effects of "antifreeze" oligopeptides and electric fields on unidirectional ice growth in thin water layers.
Katoh M, Waku T, Hagiwara Y
Soft Matter · 2026 May · PMID 42093385 · Publisher ↗
The suppression of ice crystal growth is an important issue in several fields, such as food preservation in the food industry and the preservation of cells, tissues, and organs in medicine. The use of non-toxic additives...
The suppression of ice crystal growth is an important issue in several fields, such as food preservation in the food industry and the preservation of cells, tissues, and organs in medicine. The use of non-toxic additives, such as antifreeze proteins, is effective for this suppression. Oligopeptides, which are antifreeze protein segments, have recently shown unsatisfactory suppression of ice growth in solution. This study aimed to examine whether the suppressive effect of oligopeptides could be augmented by applying direct- and alternating-current electric fields. We conducted experiments by freezing an aqueous solution of oligopeptides. Successive images of the ice/solution interface were captured using a video camera. The interface velocities were calculated from the images. In the case of water, the interface velocities around the electrodes were lower than those between the electrodes. The latter interface velocities depended on the electric fields. These findings indicate that changes in the orientation of water molecules may contribute to these variations in interface velocities. In the case of the oligopeptide solution, the dependence of the interface velocities in the middle between the electrodes on the strength of the electric field applied was inconsistent with that for water. The interface velocities around the electrodes were different when an alternating-current electric field was applied. This resulted in the migration of oligopeptides caused by the electric fields. We predicted the lateral migration of oligopeptide aggregates in cases with intermittent direct-current and alternating-current electric fields, in which the electrostatic and induced forces varied in space and time. The changes in the lateral positions of the aggregates over time were more noticeable near the electrodes than between the electrodes. This noticeable migration may disturb the local growth of crystalline ice adjacent to the aggregates.
Mechanistic insights into hydrophobicity-dependent antimicrobial selectivity of quaternary ammonium poly(oxanorborneneimide) polymers using coarse-grained simulations.
Richardson JD, Rotello VM, Van Lehn RC
Soft Matter · 2026 May · PMID 42084043 · Publisher ↗
The rapid rise of antibiotic resistance to small molecule drugs has driven the development of materials that directly target and disrupt bacterial cell membranes. Inspired by antimicrobial peptides (AMPs), synthetic poly...
The rapid rise of antibiotic resistance to small molecule drugs has driven the development of materials that directly target and disrupt bacterial cell membranes. Inspired by antimicrobial peptides (AMPs), synthetic polymers are gaining attention as promising antimicrobial materials because their molecular properties, such as hydrophobicity and charge, can be tuned to enhance selective killing of bacterial mammalian cells. Poly(oxanorborneneimide) (PONI) polymers, featuring rigid bicyclic monomer units to mimic the amphiphilicity of AMPs, have exhibited high selectivity against a broad spectrum of Gram-negative and Gram-positive bacteria over human cells depending upon their side chain functionalities. However, the mechanistic basis of this selectivity remains poorly understood, limiting the physiochemical insight needed to efficiently design new PONI polymers with enhanced selectivity. In this study, we present a molecular dynamics (MD) simulation framework to investigate PONI-membrane interactions and extract several mechanistically relevant descriptors correlated with experimentally determined activities. Building upon prior experimental studies, we model four PONI polymers with side chains of increasing hydrophobicity to understand interactions with model , methicillin-resistant (MRSA), and human red blood cell (RBC) membranes. Central to this framework, we develop a generalizable coarse-grained parameterization strategy for PONI polymers within the MARTINI 3 force field to enable simulation of polymer-membrane interactions at experimentally relevant length and timescales. Our simulations reveal that experimental activities against different membranes can be related to the propensity for PONI polymers to insert into the membrane, driven by electrostatic and hydrophobic interactions. We find that differences in membrane lipid composition, particularly strong enrichment of cardiolipin in bacterial membranes, play a critical role in the highly selective interactions of moderately hydrophobic polymers with bacterial RBC membranes, in contrast with the non-selective toxicity toward both bacterial and human RBC membranes observed with highly hydrophobic polymers.
Effects of hydrostatic pressure on epithelial dome formation and stability.
Meng J, Xie G, Zheng Y … +9 more , Chen H, Xia P, Xu P, Xu Y, Tian L, Gao Q, Tan Y, Li D, Ji B
Soft Matter · 2026 May · PMID 42065586 · Publisher ↗
Hydrostatic pressure in living organisms is crucial for the formation and stability of hollow structures in tissues and organs. However, the underlying mechanisms governing the collective cell responses to pressure in th...
Hydrostatic pressure in living organisms is crucial for the formation and stability of hollow structures in tissues and organs. However, the underlying mechanisms governing the collective cell responses to pressure in these processes have not yet been fully understood. Here, we developed a hydrostatic pressure generator to produce various pressures of physiological magnitudes and explored their effects on dome structure formation in the epithelial monolayer. We found that the positive hydrostatic pressure promoted dome formation, while the negative one suppressed it. The positive pressure induced cell autophagy and thus increased transepithelial electrical resistance, which elevated osmotic pressures inside the dome. In addition, the positive pressure induced reorganization of the actin-cytoskeleton, which stabilized the cytoskeleton network and weakened cell-matrix adhesion. Interestingly, during dome expansion, the negative pressure promoted the expansion, which eventually led to dome rupture, while the positive pressure suppressed the expansion and subsequent rupture. Our numerical simulations revealed that the negative pressure produced larger intercellular normal stress within the dome wall, making the dome more prone to rupture. These findings revealed the biophysical mechanisms by which hydrostatic pressure regulates dome formation and stability and provided insights into the effect of external pressure on collective cell behaviors during tissue morphogenesis.
Human lungs fluid mechanics: an overview of current modelling techniques.
Romanò F
Eur Phys J E Soft Matter · 2026 Apr · PMID 42053866 · Full text
Fluid mechanics governs numerous physiological processes in the respiratory system, influencing airflow dynamics, particle transport and aerosol formation, airway stability, mucus transport, surfactant mechanics, and pul...
Fluid mechanics governs numerous physiological processes in the respiratory system, influencing airflow dynamics, particle transport and aerosol formation, airway stability, mucus transport, surfactant mechanics, and pulmonary oedema. Over the past decades, engineers, physicists, and biomedical scientists have developed a wide range of models to describe these processes across multiple spatial and temporal scales. This paper provides an integrated overview of current modelling techniques in pulmonary fluid mechanics, emphasizing the multiscale and multiphysics nature of the lung. After discussing the principal challenges in simulating the mechanics of human lungs, we review the hierarchy of modelling approaches, from first-principle continuum formulations to reduced-order and data-driven models. We then explore strategies for coupling these models and conclude with a perspective on future directions, including the need for benchmark cases and clinically robust indicators for model validation.
Structural aging of a cohesive and amorphous granular solid under cyclic loading.
Hobson-Rhoades W, Durian DJ, Fan Y … +1 more , Xiao H
Soft Matter · 2026 May · PMID 42052725 · Publisher ↗
We investigate how cyclic loading evolves the structure and deformation behavior of a granular raft composed of particles floating at an air-oil interface. The raft has a disordered particle packing structure and is cohe...
We investigate how cyclic loading evolves the structure and deformation behavior of a granular raft composed of particles floating at an air-oil interface. The raft has a disordered particle packing structure and is cohesive due to capillary interactions between particles. Under uniaxial cyclic loading with a small strain amplitude, the raft's packing structure experiences an aging process characterized by logarithmically increasing packing fraction and decreasing structural heterogeneity. The observed structural change is due to particle dynamics that are organized around morphologically evolving voids in the raft. The raft is then subjected to quasi-static tension or compression tests until failure. In comparison with non-aged rafts, the rafts that experienced cyclic loading show a higher strength, higher stiffness, and lower ductility, along with qualitatively different features, such as a stress overshoot in the loading curve.
Rod particle-like viscoelastic behavior of hydroxypropylmethyl cellulose samples with narrow molar mass distributions dissolved in aqueous solutions.
Yoshida M, Nakagawa D, Arai K … +2 more , Horikawa Y, Shikata T
Soft Matter · 2026 May · PMID 42052719 · Publisher ↗
The viscoelastic behaviors of aqueous solutions of hydroxypropylmethyl cellulose (HpMC) samples with narrow molar mass distributions were investigated over a wide concentration () range. The degree of substitution by met...
The viscoelastic behaviors of aqueous solutions of hydroxypropylmethyl cellulose (HpMC) samples with narrow molar mass distributions were investigated over a wide concentration () range. The degree of substitution by methyl groups and the molar substitution number by hydroxypropyl groups of the samples were 1.8 and 0.15. The weight average molar masses () were 210, 310 and 440 kg mol, and the molar mass distribution indices were less than 1.3 for each sample. The zero-shear viscosity (), the average relaxation time (), and the steady state compliance () determined in the range for HpMC molecules to fully entangle were determined using the molecular number density ( = /, where is the Avogadro constant) and the rod particle length () of HpMC molecules. The results were reasonably understood on the basis of entangled rod particle suspension rheology, in which and are described with and is described with . Consequently, all the obtained viscoelastic data clearly revealed that the HpMC molecules behave as rod-like particles even in a fully entangled concentration range.
Interfacial ion transport in cellulose nanocrystal-based ionogels with low ionic liquid content.
Ge Y, Shultz K, Sundo J … +2 more , Paren BA, Akcora P
Soft Matter · 2026 May · PMID 42052699 · Publisher ↗
This study investigates the gel formation of cellulose nanocrystals (CNCs) in a hydrophobic ionic liquid, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (HMIm-TFSI), with the addition of a co-solvent, dime...
This study investigates the gel formation of cellulose nanocrystals (CNCs) in a hydrophobic ionic liquid, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (HMIm-TFSI), with the addition of a co-solvent, dimethylformamide (DMF). CNC-based ionogels prepared with very low HMIm-TFSI contents (0.1-0.5 wt%) exhibit higher molar ionic conductivity than gels containing larger amounts of HMIm-TFSI. Application of electric fields to CNC mixtures containing 0.4 wt% HMIm-TFSI induces CNC alignment but does not enhance macroscopic ionic conductivity, indicating that conductivity is not governed by CNC orientation. The enhanced ion mobility and conductivity of CNC-HMIm-TFSI gels are attributed to structuring of HMIm-TFSI near CNC surfaces, which facilitates efficient interfacial ionic transport. Unlike the polymer-CNC networks that are capable of confining a high amount of ionic liquid (95 wt%), the CNC gels with a low HMIm-TFSI amount can order liquids at the interfacial layers and exhibit higher conductivity than the neat ionic liquid.
Coupling of lipid phase behavior and protein oligomerization in a lattice model of raft membranes.
Basu S, Farago O
Soft Matter · 2026 May · PMID 42052686 · Publisher ↗
Membrane proteins often form dimers and higher-order oligomers whose stability and spatial organization depend sensitively on their lipid environment. To investigate the physical principles underlying this coupling, we e...
Membrane proteins often form dimers and higher-order oligomers whose stability and spatial organization depend sensitively on their lipid environment. To investigate the physical principles underlying this coupling, we employ a lattice Monte Carlo model of ternary lipid mixtures that exhibit liquid-disordered (L) and liquid-ordered (L) phase coexistence. In this framework, proteins are represented as small membrane inclusions with tunable nearest-neighbor interactions with both lipids and other proteins, allowing us to examine how protein-lipid affinity competes with protein-protein interactions and lipid-lipid demixing. We find that the balance of these interactions controls whether proteins remain dispersed, assemble into small oligomers, or form large stable clusters within L domains, and that increasing the protein concentration further promotes coarsening of the ordered phase. To incorporate ligand-regulated activation, we extend the model to a kinetic Monte Carlo scheme in which proteins stochastically switch between inactive and active states with distinct affinities. The inverse switching rate, relative to the time required for a protein to diffuse across the characteristic size of the L domains, governs the aggregation behavior. Rapid switching yields only transient small oligomers, slow switching reproduces the static limit with persistent large clusters, and intermediate rates produce broad cluster-size distributions. These results highlight the interplay between lipid phase organization, protein-lipid affinity, and activation dynamics in regulating membrane protein oligomerization, a coupling that is central to signal transduction and membrane organization in living cells.
Reconstitution of metabolic reactions within self-assembled, multi-compartment protein vesicles.
Shin J, Woods W, Jang Y
Soft Matter · 2026 May · PMID 42052638 · Publisher ↗
Artificial cells that reproduce the spatial organization of metabolism offer a powerful platform for understanding and controlling complex biochemical pathways. In this work, we engineer globular protein vesicles (GPVs)...
Artificial cells that reproduce the spatial organization of metabolism offer a powerful platform for understanding and controlling complex biochemical pathways. In this work, we engineer globular protein vesicles (GPVs) by exhibiting octopine dehydrogenase (ODH), a model monomeric enzyme, on vesicle membranes through the self-assembly of recombinant fusion proteins. The enzymatic GPVs are constructed from two complementary fusion protein building blocks: ODH fused with a glutamic acid-rich leucine zipper (ODH-Z) and an elastin-like polypeptide fused with an arginine-rich leucine zipper (Z-ELP). The oppositely charged leucine zipper pairs (Z and Z) form a heterodimer electrostatic interactions, driving vesicle assembly. Because these interactions are sensitive to ionic strength and stoichiometry, we investigate the effects of salt concentration and molar ratio on self-assembly behavior and vesicle morphology. Enzymatic assays show that ODH displayed on GPVs exhibits enhanced stability and sustained catalytic activity compared to the free enzyme. To recapitulate a two-step enzyme cascade representing the terminal steps of glycolysis and anaerobic fermentation observed in marine invertebrates, we created a hierarchical multicompartment architecture consisting of nanoscale ODH-displaying vesicles (∼500 nm in diameter) encapsulated within giant GPVs (tens of micrometers). We further engineered co-encapsulation and nested configurations to control pyruvate generation and transport across compartments. Fluorescence-based monitoring of NADH consumption reveals that these architectures produce distinct reaction kinetics, underscoring the role of spatial organization in modulating enzymatic behavior. Together, these results highlight the potential of GPVs as customizable platforms for rebuilding metabolic processes within artificial cell-like compartments.
The effect of weathering environments on microplastic chemical identification with Raman and IR spectroscopy: Part II. polystyrene, polyethylene terephthalate, and nylon 6.
Phan S, Ramtahal JJ, Luscombe CK
Soft Matter · 2026 May · PMID 42046971 · Publisher ↗
The use of spectroscopic techniques to identify microplastics found in the environment is challenging because weathered microplastics undergo chemical changes that make their spectra drastically different from their pris...
The use of spectroscopic techniques to identify microplastics found in the environment is challenging because weathered microplastics undergo chemical changes that make their spectra drastically different from their pristine counterparts. In previous work, we reported the findings from systematic artificial weathering of polyethylene and polypropylene for 0-26 weeks in four different weathering environments (air, DI water, artificial seawater, and Puget Sound seawater), characterized by Raman and IR spectroscopy (https://doi.org/10.1016/j.polymertesting.2022.107752). This manuscript provides the final part of the study's findings, which includes the Raman and IR spectroscopy information on the weathering effects on polystyrene (PS), polyethylene terephthalate (PET), and nylon 6 (PA6) with the goal to evaluate how these weathering effects affect the reliability of polymer identification. Our results show that spectral changes are often non-linear, lacking a clear exposure-time trend. While PS exhibited significant oxidation by IR in DI water, these changes were not detectable by Raman spectroscopy, highlighting a risk for researchers who rely on a single technique. Both PS and PA6 showed more degradation peaks in DI water than in seawater, which suggests that chlorine radicals from salt may inhibit the formation of some degradation products. This work underscores the need to use complementary IR and Raman analysis to avoid misinterpretation of environmental microplastics and their aging state.
Following the formation of single-chain nanoparticles generated by interblock crosslinking within diblock copolymers: a Monte Carlo simulation study with adjustable interaction strength between the blocks.
Voigt A, Strauch C, Höfken T … +6 more , Wahab M, Hadwich W, Barner-Kowollik C, Hübler C, Schneider S, Plamper FA
Soft Matter · 2026 May · PMID 42046932 · Publisher ↗
We investigated the folding and crosslinking of diblock copolymers with interblock-crosslinkable units in dilute solution. We used a bead-spring model for the polymer and Monte Carlo simulations for the crosslinking. At...
We investigated the folding and crosslinking of diblock copolymers with interblock-crosslinkable units in dilute solution. We used a bead-spring model for the polymer and Monte Carlo simulations for the crosslinking. At no and small interblock attractive interaction, the observed zipping between spatially proximate crosslinkers results in single-chain nanoparticles resembling expanded ladder-type polymers. Stronger attractive interactions between the different blocks lead to an enhanced internal confinement resulting in more compact, randomly crosslinked structures. The structural outcome of the "reactive" Monte Carlo (MC) simulations was also qualitatively recovered by applying "reactive" molecular dynamics (MD) simulations.
Dynamics of particles suspended in field-enhanced microscale flows.
Halder D, Yee A, Yoda M … +1 more , Prakash S
Soft Matter · 2026 Jun · PMID 42037513 · Publisher ↗
Understanding the dynamics of particles suspended in a flowing liquid is a fundamental fluid mechanics problem. Over the last several decades, significant advances in our theoretical and experimental understanding of the...
Understanding the dynamics of particles suspended in a flowing liquid is a fundamental fluid mechanics problem. Over the last several decades, significant advances in our theoretical and experimental understanding of these particle-laden flows have been used to manipulate particles in a variety of applications. In particular, recent developments in micro- and nanoscale fabrication and nanotechnology have increased the range of applications, as well as requirements, for manipulating suspended particles with radii less than a few micrometers. We focus here on the surprising and largely unexplained dynamics of neutrally buoyant particles suspended in two common microscale flows, namely Poiseuille and electroosmotic flows, where the particles are subject to both surface forces (, due to pressure gradients) and body forces (, due to electric fields). This perspective review summarizes current developments and identifies opportunities for future advances. Particles suspended in flows can demonstrate both individual and collective behaviors that lead to unusual and unexpected physicochemical hydrodynamics. These dynamics are a long-standing subject of interest, and there has been significant research on the fundamentals of particle-fluid interactions and suspension dynamics because of their relevance to nano- and microscale robotics, drug delivery, biosensing, nanomaterials, optical systems, and biotechnology. The review focuses on the dynamics of nanoscale colloidal particles within confined microscale flows, discussing past discoveries and current state-of-art research, and concluding with suggestions for future research directions.
Dynamic water film assisted laser micromachining of micro-array structured surfaces for inducing hydrophobicity: analysis model and experimental study.
Yang J, Lian Z, Jin H … +3 more , Wang J, Xu J, Tian Y
Soft Matter · 2026 May · PMID 42028926 · Publisher ↗
With the advantages of non-contact processing and high precision, laser micromachining technology has shown great potential for applications in functional surface fabrication. However, thermal damage issues inevitably ar...
With the advantages of non-contact processing and high precision, laser micromachining technology has shown great potential for applications in functional surface fabrication. However, thermal damage issues inevitably arise during the machining process. This study takes Ti6Al4V titanium alloy as the research object and compares the processing effects of laser direct processing (LDP) and dynamic water film assisted laser machining (DWFALM). The effects of varying laser processing spacing on surface morphology and wetting properties were investigated. The results indicate that, compared with the conventional LDP technique, DWFALM reduces the extent of the heat-affected zone (HAZ), suppresses molten layer formation, and mitigates microcrack defects. By adjusting the scanning spacing, a superhydrophobic surface with a contact angle (CA) of up to 167.6° and a rolling angle (RA) as low as 2.2° was fabricated. In addition, the CA prediction model established in this study was consistent with the experimental measurements, with an average error below 2%. This research achievement not only provides theoretical guidance for the controllable preparation of superhydrophobic surfaces but also offers new approaches for achieving efficient and low damage surface processing. The micro-array-structured superhydrophobic Ti6Al4V surface fabricated by DWFALM shows potential for applications in anti-fouling, anti-icing, seawater desalination, and related fields.
Soft matrix: probing local mechanical properties in amorphous solids.
Sreekumari A, Adhikari M, Pingua N … +5 more , Krishnan VV, Sengupta S, Chaudhuri P, Karmakar S, Vasisht VV
Soft Matter · 2026 May · PMID 42026986 · Publisher ↗
Understanding how amorphous solids yield under shear is central to predicting material failure, yet prescribing reliable local yielding criteria remains a fundamental challenge. Here we introduce the soft matrix method,...
Understanding how amorphous solids yield under shear is central to predicting material failure, yet prescribing reliable local yielding criteria remains a fundamental challenge. Here we introduce the soft matrix method, which creates a minimally constrained and elastically coupled environment that allows localized regions of an amorphous solid to yield naturally. This method overcomes key limitations of earlier approaches and provides a robust platform for probing failure mechanisms in soft disordered materials. Using this framework, we analyze localized yielding by systematically varying the size of the local probe region in our microscopic simulations, and we uncover an intrinsic length scale () that governs local failure, showing that grows with the age of the system. The age dependence appears not only in the distribution of local yield stresses but also in the pseudogap exponent , which quantifies the marginal stability of amorphous solids. These insights offer a pathway toward improved elastoplastic modeling of disordered materials.
Self-assembly of quasicrystals under cyclic shear.
Maire R, Plati A, Smallenburg F … +1 more , Foffi G
Soft Matter · 2026 May · PMID 42023720 · Publisher ↗
We investigate the self-assembly of two-dimensional dodecagonal quasicrystals driven by cyclic shear, effectively replacing thermal fluctuations with plastic rearrangements. Using particles interacting a smoothed square...
We investigate the self-assembly of two-dimensional dodecagonal quasicrystals driven by cyclic shear, effectively replacing thermal fluctuations with plastic rearrangements. Using particles interacting a smoothed square-shoulder potential, we demonstrate that cyclic shearing drives initially random configurations into ordered quasicrystalline states. The resulting non-equilibrium phase diagram qualitatively mirrors that of thermal equilibrium, exhibiting square, quasicrystalline, and hexagonal phases, as well as phase coexistence. Remarkably, the shear-stabilised quasicrystal appears even where the zero-temperature equilibrium ground state favours square-hexagonal coexistence, suggesting that mechanical driving can stabilise quasicrystalline order in a way analogous to entropic effects in thermal systems. The structural quality of the self-assembled state is maximised near the yielding transition, even though the dynamics are slowest there. Yet, the system still quickly forms monodomain quasicrystals without any complex annealing protocols, unlike at equilibrium, where thermal annealing would be required. Finite-size scaling analysis reveals that global orientational order decays slowly with system size, indicative of quasi-long-range order comparable to equilibrium hexatic phases. Overall, our results establish cyclic shear as an efficient pathway for the self-assembly of complex structures.
Molecular dynamics investigation of the impact of methylation on the nematic phase of phenyl benzoate mesogens and dimers.
Votava JS, Davidson EC, Webb MA
Soft Matter · 2026 May · PMID 42023546 · Publisher ↗
Liquid crystals (LCs) possess anisotropic mechanical and optical properties with applications ranging from soft robotics to display technology. Despite advances in the precise synthesis of liquid crystalline materials, t...
Liquid crystals (LCs) possess anisotropic mechanical and optical properties with applications ranging from soft robotics to display technology. Despite advances in the precise synthesis of liquid crystalline materials, the microscopic origins of substituent effects, which impact functional performance, are not always well understood. Here, we use molecular dynamics (MD) simulations to investigate how methyl substitution affects the nematic phase behavior of liquid crystal monomers and dimers composed of phenyl benzoate cores flanked by aliphatic tails. Methylation induces a decrease in the nematic-isotropic transition temperature. Using data-driven analysis, we find that for monomers this decrease is associated with an increase in flexibility of core-adjacent aliphatic torsions that influence overall mesogen conformation. For dimers, this manifests as a shift from a continuum of accessible conformations in the isotropic phase to occupying more distinct hairpin and extended states in the nematic phase. The latter exhibits a bend angle consistent with experimental signatures of a modulated nematic phase. Together, these results show how minor changes in chemical structure can impact the conformational ensemble of liquid crystals, trading local conformational entropy for global nematic order, in turn influencing their macroscopic transition temperatures.
Delamination and out-of-plane deformation in drying colloidal suspensions.
Lilin P, van Rees WM, Ibrahim M … +1 more , Bischofberger I
Soft Matter · 2026 May · PMID 42017343 · Publisher ↗
A drop of a colloidal suspension placed on a substrate forms a solid particle deposit as it dries. As water evaporates, large gradients in pore pressure inside the porous deposit cause shrinkage and stresses. The deposit...
A drop of a colloidal suspension placed on a substrate forms a solid particle deposit as it dries. As water evaporates, large gradients in pore pressure inside the porous deposit cause shrinkage and stresses. The deposit cracks, then delaminates from the substrate, and bends out of plane, creating a striking three-dimensional structure. Previous models have attributed the out-of-plane deformation to pore pressure gradients through the deposit's thickness, a hypothesis our findings contradict. Through a combination of interference and confocal microscopy, we show that the final curvature strongly depends on the deposit thickness, with thinner deposits curving more. We propose a mechanism where the curvature is driven not by vertical pressure gradients, but by much larger radial pressure gradients across the length of the deposit. The resulting in-plane differential shrinkage creates geometric frustration that is resolved through out-of-plane buckling. We validate this mechanism using non-Euclidean plate simulations, which successfully reproduce the buckling behavior and the observed dependence of curvature on thickness.
Dynamics of Marangoni-driven elliptical Janus particles.
Masanta P, Sarkar R, Parmananda P … +1 more , Chelakkot R
Soft Matter · 2026 May · PMID 42011710 · Publisher ↗
We investigate the spontaneous motion of an elliptical Janus particle, driven by Marangoni forces, on a water surface to understand how particle shape and size influence its dynamics. The Janus particle is one-half infus...
We investigate the spontaneous motion of an elliptical Janus particle, driven by Marangoni forces, on a water surface to understand how particle shape and size influence its dynamics. The Janus particle is one-half infused with a substance such as camphor, which lowers the surface tension upon release onto the water surface. The resulting surface tension gradient generates Marangoni forces that propel the particle. For fully camphor-infused (non-Janus) particles, previous studies have shown that motion occurs along the short axis of the ellipse. However, for Janus particles, our experiments reveal a much richer steady-state dynamics, depending on both the particle's eccentricity and size. To understand these dynamics, we develop a numerical model that captures the connection between the spatio-temporal evolution of the camphor concentration field and the Marangoni force driving the particle. Using this model, we simulate the motion of particles with varying eccentricities-from nearly circular to highly elongated shapes. The simulations qualitatively reproduce all the trajectories observed in experiments and provide insights into how particle geometry influences the dynamics of chemically driven anisotropic particles. With the help of the numerical model, we compute a full phase diagram characterising the dynamical states as a function of surfactant properties.
Dynamics of emulsion drop impact, spreading and evaporation: the effect of internal phase gelation.
Cordova-Gonzalez M, Bazazi P, Hejazi SH
Soft Matter · 2026 May · PMID 42011707 · Publisher ↗
The dynamics of drop impact, spreading, and evaporation on solid surfaces are fundamental to many processes, including agricultural spraying, printing, combustion, and coating. While these behaviors are well understood f...
The dynamics of drop impact, spreading, and evaporation on solid surfaces are fundamental to many processes, including agricultural spraying, printing, combustion, and coating. While these behaviors are well understood for single phase liquids, less is known about emulsions with complex internal structures. Here, we report an experimental study on the dynamics of water-in-oil emulsion droplets containing either liquid or gelled aqueous phases. The continuous phase is composed of -heptane and Span 80 micelles, while the dispersed phase is a reactive sodium silicate-ammonium bicarbonate solution that undergoes gelation. Internal gelation changes the rheological response of the dispersed phase and therefore modifies dissipation during spreading and drying. During the impact stage, the dynamics are similar for both emulsion types within our experimental resolution, whereas during the subsequent spreading stage, gel-containing emulsions reach smaller wetted areas. Measured maximum spreading factors are broadly consistent with unified inertial-capillary-viscous scaling for water emulsions, while gel emulsions show systematic deviations at higher internal-phase fractions. Bottom-view fluorescence imaging reveals distinct drying patterns: isolated circular deposits for water emulsions and rugged, interconnected structures for gel emulsions. These findings highlight the importance of the internal droplet structure in governing impact and drying dynamics, with implications for a wide range of emulsion-based technologies.
Entropic depletion of macromolecular solutes induces symmetry-breaking surface wrinkling in myelin figures.
Vyas AP, Sambre PD, Wang L … +2 more , Deshmukh P, Parikh AN
Soft Matter · 2026 May · PMID 42011525 · Publisher ↗
Smectic liquid crystals, including multilamellar stacked lipid bilayers, strongly resist compression along the normal layer but bend readily. When mechanically stressed-such as by dehydration, osmotic stress, physical co...
Smectic liquid crystals, including multilamellar stacked lipid bilayers, strongly resist compression along the normal layer but bend readily. When mechanically stressed-such as by dehydration, osmotic stress, physical confinement, or even electric fields-they release elastic compressive energy by buckling into undulatory surface patterns reminiscent of the well-known Helfrich-Hurault instability. Although documented extensively for lamellar liquid crystals, observations of the Helfrich-Hurault instability in cylindrical smectic liquid crystals are scant. Here, we investigate the behavior of myelin figures-cylindrical smectic-A liquid crystals consisting of thousands of concentric amphiphilic bilayer lamellae separated by aqueous channels-when subjected to mechanical compression by the hyperosmotic stress from the osmolyte-laden surrounding bath. We find that the colligative ideal osmotic pressure exerted by small molecular osmolytes alone is insufficient to induce long-lived, surface instabilities. Using real-time optical and confocal fluorescence microscopy, we show that exposure to hypertonic solutions of low-molecular-weight osmolytes (, sucrose and glycerol) leaves myelin surfaces largely smooth, even at elevated osmotic pressures. By contrast, solutions containing macromolecular osmolytes such as polyethylene glycol and dextran trigger pronounced symmetry-breaking surface instabilities in bundles of juxtaposed myelins. These instabilities manifest as long-wavelength, quasi-sinusoidal corrugations that propagate axially and preferentially localize at inter-myelin interfaces. Quantitative analysis reveals that the wavelength and amplitude of the corrugations depend on osmolyte size, even at nominally identical osmotic pressures, further implicating excluded-volume effects. Fluorescently labeled osmolytes are excluded from corrugated interfacial regions, supporting a depletion-driven mechanism. We propose that macromolecular osmolytes generate colligatively non-ideal osmotic stresses and entropic depletion forces that stabilize interlocking surface undulations by increasing the free volume available to the depletants. These findings identify solute entropy and excluded-volume interactions as key drivers that stabilize Helfrich-Hurault-type undulatory instabilities in cylindrical smectics. They further suggest a general physical mechanism by which macromolecular crowding can induce large-scale structural remodeling in soft, multilamellar systems relevant to both synthetic materials and biological assemblies.
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