Soft Matter[JOURNAL]
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200 papers
Ion size controls the conductivity of solid polymer electrolytes.
Rajahmundry GK, Patra TK
Soft Matter · 2026 Jun · PMID 42201757 · Publisher ↗
Solid polymer electrolytes (SPEs) are ion-containing solid materials composed of a polymer matrix that enables ionic transport while maintaining mechanical stability. The correlations among ion clustering, microstructure...
Solid polymer electrolytes (SPEs) are ion-containing solid materials composed of a polymer matrix that enables ionic transport while maintaining mechanical stability. The correlations among ion clustering, microstructure, and conductivity of SPEs are of significant interest for the development of more efficient energy storage materials. In pursuit of this objective, here, we assess and elucidate the effects of cation-anion and ion-monomer size ratios on the conductivity of a model SPE. We show that high ion-monomer and cation-anion size asymmetries promote better mixing of the ions with the polymer matrix. Under these conditions, the ion-dipole moment interaction dominates over the ion-ion interaction and improves the ion dispersion in the polymer matrix. At the same time, these interactions are not sufficiently strong to induce persistent ion pair localization, thereby facilitating faster ion transport. These two size ratios are thus key to tailoring the properties of SPEs with immediate relevance to the development of SPEs for energy storage devices.
Viscoelasticity and elastoplasticity in the power law creep and yielding of gels and fibre network materials under stress.
Hertaeg MJ, Fielding SM
Soft Matter · 2026 Jun · PMID 42201753 · Publisher ↗
We study computationally the creep and yielding of athermal gels and fibre network materials under a constant imposed shear stress, within a minimal model of interconnected filaments with central forces in = 2 spatial d...
We study computationally the creep and yielding of athermal gels and fibre network materials under a constant imposed shear stress, within a minimal model of interconnected filaments with central forces in = 2 spatial dimensions. Each filament is assumed Hookean initially, then breaks irreversibly above a threshold strain. At early times after the imposition of a small stress, we find purely viscoelastic creep response associated with non-affine deformations within the material, with solid terminal behaviour for a network coordination > 2 = 4 and initially floppy response for < 4. For a marginally connected network, = 4, we find sustained power law creep with a strain rate ∼ and strain ∼ as a function of time after the imposition of the stress. This viscoelastic regime gives way at later times to elastoplastic creep arising from filament breakage, broadening the range of values of and time over which power law creep occurs, compared to a network with filament breakage disallowed. This accumulating filament breakage can weaken the network to such an extent that catastrophic material failure then occurs after a long delay, which we characterise. Finally, we consider the implications of viscoelastic elastoplastic deformation for the extent to which a material will recover its original shape if the load is removed after some interval of creep.
Cruising and jumping: the effect of microplastics on the swimming behavior of copepods measured by 3D Lagrangian particle tracking velocimetry.
Michalec FG, Praud O, Lorite-Diez M … +3 more , Cazin S, Souissi S, Climent E
Eur Phys J E Soft Matter · 2026 May · PMID 42201637 · Full text
Calanoid copepods are key components of marine and estuarine food webs. Exposure to various classes of pollutants induces changes in their swimming behavior. This raises concerns about potential effects on critical proce...
Calanoid copepods are key components of marine and estuarine food webs. Exposure to various classes of pollutants induces changes in their swimming behavior. This raises concerns about potential effects on critical processes such as feeding, mating, predator avoidance and vertical migration. The effect of pollution by microplastics is not well known. We investigated in a large experimental tank the effects of the smallest size fraction of microplastics on the swimming behavior of the estuarine copepod Eurytemora affinis. Because the motion of zooplankton is intrinsically linked to that of the ambient fluid, we recorded copepods moving freely in calm water and in grid-generated turbulence to recreate some of the hydrodynamic conditions they experience in their natural environment. Using an advanced implementation of 3D Lagrangian particle tracking velocimetry, we simultaneously measured copepod trajectories and the surrounding flow field at high temporal resolution. In calm water, copepods alternated between periods of cruising and sudden relocation jumps. In turbulence, copepod motion was dominated by transport by the flow, yet jumps allowed copepods to deviate from the flow streamlines. The measurement of the relative velocity of copepods with respect to the underlying flow enabled us to characterize the statistics of these jumps. Turbulence significantly increased jump frequency without modifying their amplitude or duration. Following a 12-hour exposure to polyethylene fragments at 300 g/L, copepods showed increased jump frequency in calm water corresponding to 40 % increase in energetic cost. In contrast, exposure to microplastics produced weak additional effects on swimming behavior under turbulent conditions. These results confirm the existence of an active response to turbulence in E. affinis and are consistent with a hyperactive behavior triggered by exposure to microplastic pollution.
The impact of a compound drop on a solid surface: the influence of shell viscosity.
Singh RR, Mandal DK
Soft Matter · 2026 Jun · PMID 42201319 · Publisher ↗
A study of a compound drop impacting a surface is presented. The drop is of single-core, shell type, with the shell containing oil at three viscosities (1, 10, and 100 cSt) and the core containing water. The influence of...
A study of a compound drop impacting a surface is presented. The drop is of single-core, shell type, with the shell containing oil at three viscosities (1, 10, and 100 cSt) and the core containing water. The influence of varying viscosities and the Weber number (We) on impact is reported. The spread dynamics are found to be majorly influenced by the shell. With a rise in shell viscosity, the maximum spreading factor (, maximum spread's ratio to the drop's pre-impact diameter) declines for a given impact velocity. At higher impact velocities, finger formation at the outer periphery and splash are comprehended for the low and medium-viscosity shells, respectively. The shell forms a film for the core to spread and retract, and thereby influences the core's spreading and retracting dynamics. At lower Reynolds numbers (Re) for the 1 cSt shell and all Re for the 10 cSt shell drops, total separation of the core at the end of retraction is reported. Partial separation is observed for lower viscosity shells at higher Re, while no separation is found in higher viscosity shells. The physics of the core jet length until separation is explored. To verify the shell's viscosity influence, the measured is compared with a theoretical model developed indigenously. A good comparison is observed. The novelty lies in demonstrating a systematic experimental study of compound drops focused on shell viscosity, and in developing a simplified model to predict the maximum spread.
Transient negative capacitance in ferroelectric and twist-bend ferroelectric nematic liquid crystals.
Dhakal NP, Talwar M, Siddiquee Z … +4 more , Karcz J, Kula P, Salamon P, Jákli A
Soft Matter · 2026 Jun · PMID 42199057 · Publisher ↗
The negative capacitance (NC) of ferroelectric materials can be used in conventional electronics to reduce power dissipation. Recently, NC was shown (N. P. Dhakal, A. Adaka, R. J. Twieg, N. A. Clark and A. Jákli, , 2025,...
The negative capacitance (NC) of ferroelectric materials can be used in conventional electronics to reduce power dissipation. Recently, NC was shown (N. P. Dhakal, A. Adaka, R. J. Twieg, N. A. Clark and A. Jákli, , 2025, , 014029, DOI: 10.1103/fjx3-jd2y) to exist in a fluid ferroelectric nematic (N) liquid crystal material as well. Studies presented in this paper strongly indicate that NC exists in all ferroelectric nematic liquid crystal materials provided that the polarization switching time is larger than the rise time of the applied square-wave voltage. Additionally, NC was studied in a recently discovered fluid twist-bend ferroelectric nematic liquid crystal (N) material while switching its ferroelectric polarization. In contrast to the 2 NC ranges found in conventional ferroelectric crystals and ferroelectric nematic liquid crystals, in the N phase, the polarization switching happens in two steps leading to four negative capacitance ranges in the - hysteresis curves. Our measurements and analyses also provide estimates of the rotational viscosities and the physical mechanisms of the polarization switching steps in the N phase.
Modeling elastoviscoplastic materials using physics-informed neural networks.
Valipour Goodarzi B, Foudazi R
Soft Matter · 2026 Jun · PMID 42189592 · Publisher ↗
Elastoviscoplastic (EVP) materials pose significant challenges for predictive modeling, especially under large amplitude oscillatory shear (LAOS) conditions due to their nonlinear rheological behavior. While various mode...
Elastoviscoplastic (EVP) materials pose significant challenges for predictive modeling, especially under large amplitude oscillatory shear (LAOS) conditions due to their nonlinear rheological behavior. While various models have been proposed to describe yielding and viscoelastic transitions, their application to experimental data remains limited due to computational complexity, poor generalizability, and difficulty in fitting noisy data. This work re-evaluates rheological modeling of EVP materials by using a physics-informed neural network (PINN) approach that embeds a modified Saramito model into the training framework. By directly fitting time-dependent stress data on typical EVP materials, this method circumvents the need for gradient estimation from noisy measurements and offers a data-efficient, differentiable, and generalizable alternative to conventional fitting methods. A shear-thinning formulation is introduced to reflect the decreasing viscosity at higher strain amplitudes. The proposed PINN approach is validated using both synthetic and experimental data, demonstrating stable recovery of physical parameters, enhanced interpretability, and improved predictive capability across a range of strain amplitudes. This framework bridges microstructural deformation modes with rheological modeling, offering a powerful tool for understanding and predicting nonlinear viscoelastic behavior in soft matter.
Plug flow down to the nanoscale can induce partial solidification of confined fluids.
Chen S, Zhang H, Guo Z … +2 more , Pagonabarraga I, Zhang X
Soft Matter · 2026 Jun · PMID 42188720 · Publisher ↗
In this work, we employ molecular dynamics simulation to study the anomalous fluid behavior of plug nanoflows. We find that the simultaneous use of plugging and nano-confinement suppresses the ability of fluids to flow,...
In this work, we employ molecular dynamics simulation to study the anomalous fluid behavior of plug nanoflows. We find that the simultaneous use of plugging and nano-confinement suppresses the ability of fluids to flow, leading to molecular clogging. Our simulations demonstrate that molecular clogging enhances the fluid/solid friction in a non-linear manner and leads to various novel flow patterns. Our analysis reveals that the non-monotonic friction behavior is a consequence of the sudden transition of the confined fluid from a liquid state to a partial solid-like state when the pore size decreases. The partial solidification features a piecewise response of the liquid velocity, pressure, and density distributions. The solidification in fact originates from the combined action of clogging and interfacial friction: clogging increases friction, inducing an enhanced internal compression of the confined liquid that causes partial solidification. The driving mode also critically alters the flow patterns: constant-velocity driving yields piecewise flow profiles, while constant-force driving triggers abrupt stick-slip transitions in small pores where solidification occurs. Our findings challenge the traditional view of confined fluids as homogeneous liquids and establish a compression-based mechanism linking interfacial friction, molecular clogging, and flow-induced solidification.
On the role of surfactants in emulsions and foams.
Langevin D
Soft Matter · 2026 Jun · PMID 42186981 · Publisher ↗
This perspective article is centered around my work related to surfactant science. The field is multidisciplinary, linked to physics, chemistry and biology. It is part of the field of soft matter and is well connected to...
This perspective article is centered around my work related to surfactant science. The field is multidisciplinary, linked to physics, chemistry and biology. It is part of the field of soft matter and is well connected to industrial applications. My particular expertise deals with liquid surfaces, an area that expanded considerably with the advent of miniaturization, , when surfaces begin to matter. I started my research with surface light scattering and surface rheology investigations. The light scattering technique allows measurements of low interfacial tension systems, and led me to investigate microemulsions. After this work, I used my knowledge in surface rheology to investigate emulsions and foams, which are not thermodynamically stable, in contrast with microemulsions. The work is still ongoing, in particular to reach a better understanding of coalescence of bubbles and drops. I will show how interesting it is to use knowledge on surface layers at macroscopic interfaces to better understand microemulsions, emulsions and foams. I conclude with considerations on the perspectives of the research field.
Mechanically robust PEDOT:PSS hydrogel mild liquid metal crosslinking.
Zhou Q, Azapagic A, Eiting A … +5 more , Won S, Boyadzhiev A, Sant H, Fernandes DCC, Zhang H
Soft Matter · 2026 Jun · PMID 42171437 · Publisher ↗
Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) hydrogels are promising for bioelectronic applications but are constrained by the lack of mild processing strategies and limited mechanical robustness. I...
Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) hydrogels are promising for bioelectronic applications but are constrained by the lack of mild processing strategies and limited mechanical robustness. In this work, we report a crosslinking strategy for PEDOT:PSS hydrogels based on eutectic gallium-indium (EGaIn). In aqueous environments, Ga releases Ga ions that interact with PSS chains, modifying the electrostatic interactions between the PEDOT chain and the PSS chain to form ionic crosslinks within the polymer network. The resulting Ga-crosslinked PEDOT:PSS hydrogels exhibit a storage modulus (') of up to 2500 Pa. Microscopic characterization reveals a transition from a porous structure to a more compact, flake-like morphology, which contributes to the improved mechanical stability. Ga crosslinking leads to a reduction in electrical conductivity, reflecting the altered polymer interactions associated with ionic crosslink formation. The combination of mechanical enhancement and preserved ionic-electronic mixed conduction suggests that these hydrogels hold promise for organic electrochemical transistor (OECT) applications, where reduced initial conductivity can be advantageous for device operation.
Hopping dynamics of a tracer particle confined in a fluctuating lattice.
Kim S, Song Y, Sung BJ … +2 more , Saito S, Kim JS
Soft Matter · 2026 Jun · PMID 42171327 · Publisher ↗
We investigate the hopping dynamics of a tracer particle in a two-dimensional fluctuating lattice using Brownian dynamics simulations. Conventional analyses based on the mean square displacement and the self-intermediate...
We investigate the hopping dynamics of a tracer particle in a two-dimensional fluctuating lattice using Brownian dynamics simulations. Conventional analyses based on the mean square displacement and the self-intermediate scattering function reveal subdiffusive behavior characteristic of hopping transport, but these averaged quantities cannot resolve individual hopping events. To overcome this limitation, we apply hop functions originally developed for glassy and supercooled liquids, which enable the identification of discrete hopping events and provide microscopic insight into tracer dynamics. In this fluctuating lattice, direct tracking of tracer trajectories between interstitial sites offers a clear reference for validating hop-function definitions. We systematically evaluate different formulations by assessing their accuracy in identifying hopping events, reproducing residence-time distributions, and predicting free-energy barriers from hop-function probability distributions. Our results demonstrate that, among the tested formulations, the newly proposed () yields the most accurate identification of hopping events and achieves excellent quantitative agreement with both direct trajectory tracking and umbrella-sampling free-energy barriers across a wide range of fluctuation regimes. These findings establish hop-function analysis as a robust and quantitatively reliable tool for characterizing tracer dynamics in confined, thermally fluctuating environments.
The sinking dynamics of a solid intruder in concentrated cornstarch suspensions studied using ultra-fast magnetic resonance imaging.
Kirov NK, McLaren CP, Pruessmann KP … +2 more , Müller CR, Penn A
Soft Matter · 2026 Jun · PMID 42171320 · Full text
The sinking of intruders in concentrated cornstarch suspensions is governed by localized, transient dynamics that are difficult to access experimentally because of the opacity of the material. Here, we use real-time magn...
The sinking of intruders in concentrated cornstarch suspensions is governed by localized, transient dynamics that are difficult to access experimentally because of the opacity of the material. Here, we use real-time magnetic resonance imaging (MRI) to investigate the sinking of spherical intruders in cornstarch suspensions at solid fractions = 0.41 and 0.44. Ultra-fast 1D MRI measurements show that, consistent with earlier reports, the intruders pass through an impact transient, an oscillatory sinking regime, and late stop and go cycles near the bottom boundary. By varying the intruder diameter at fixed suspension composition, we find that larger intruders sink more slowly, while the oscillations in the intermediate sinking regime exhibit similar characteristic frequencies and amplitudes for all three sizes. A reduced drag-memory model further shows that these oscillatory sinking velocities can be described reasonably well by a common phenomenological history-dependent response for the presented conditions. The 1D MRI signal maps reveal synchronous signal modulations around the intruder, indicating that the oscillatory motion is coupled to repeated growth and partial relaxation of a perturbed suspension region. Complementary 2D MR velocimetry shows that the motion is not purely vertical, but also includes oscillations in the horizontal direction. We show that the surrounding flow and strain rate fields are strongly heterogeneous, with deformation becoming progressively concentrated beneath the intruder prior to arrest.
Modeling the slow Arrhenius process (SAP) in polymers.
Ginzburg VV, Gendelman OV, Napolitano S … +2 more , Casalini R, Zaccone A
Soft Matter · 2026 Jun · PMID 42171270 · Publisher ↗
Amorphous glass-forming polymers exhibit multiple relaxation processes, including the structural α-relaxation associated with the glass transition and faster secondary relaxations that typically follow Arrhenius behavior...
Amorphous glass-forming polymers exhibit multiple relaxation processes, including the structural α-relaxation associated with the glass transition and faster secondary relaxations that typically follow Arrhenius behavior. Recently, a distinct slow Arrhenius process (SAP) has been observed at frequencies well below the α-process. Although Arrhenian in its temperature dependence, the SAP involves much longer relaxation times, and its microscopic origin remains unclear. Here, we extend the two-state, two-timescale (TS2) theory to describe both the α-relaxation and the SAP within a unified framework. We propose that the SAP represents the high-temperature limit of an αβ-like process in a coarse-grained fluid of dynamically correlated clusters. With renormalized interaction energies and coordination parameters, the same model quantitatively reproduces both α and SAP data across multiple polymers without additional adjustable parameters and explains the observed Meyer-Neldel compensation behavior. The theory further predicts that the SAP should deviate from Arrhenius behavior at sufficiently low temperatures, transitioning to Vogel-Fulcher-Tammann-Hesse-like dynamics, thereby offering a physically transparent interpretation of cluster-scale relaxation in glass-forming polymers.
Cooperative effect of local active stresses on the macroscopic contractility of elastic fiber networks.
Kumar A, Quint DA, Dasbiswas K
Soft Matter · 2026 Jun · PMID 42171246 · Publisher ↗
The collective action of actively contractile units embedded in elastic biopolymer networks plays a crucial role in regulating the network's macroscopic mechanical response. Here, we investigate how the macroscopic bound...
The collective action of actively contractile units embedded in elastic biopolymer networks plays a crucial role in regulating the network's macroscopic mechanical response. Here, we investigate how the macroscopic boundary stress in model elastic fiber networks depends on the number and nature of embedded contractile units, each exerting an isotropic force dipole, as well as on the bending stiffness of fibers. We find that the macroscopic stress increases nonlinearly with the number of dipoles due to mutual stiffening of initially soft, bending-dominated networks. Using effective medium theory, we relate this enhanced contractility to an increase in the effective average network coordination number due to constraints imposed by the force dipoles. By comparing three distinct force dipole models that differ in their local structures, we demonstrate that the specific manner in which an active unit constrains the network strongly influences the onset and nature of the stiffening transition. Our results highlight that not only the quantity but also the local geometry of force-generating units critically determines the macroscopic mechanical behavior. This framework provides a physical basis for understanding how biological systems-such as molecular motors in the cytoskeleton, or adherent cells in the extracellular matrix-can modulate network-scale nonlinear elastic properties through local tuning of active force-generating units.
A simple model for poration-induced electrodeformation of giant vesicles.
Thaokar RM, Kumar R, Behera N … +1 more , Maoyafikuddin M
Soft Matter · 2026 Jun · PMID 42171221 · Publisher ↗
This work attempts to understand the mechanism of poration induced deformation in giant unilamellar vesicles (GUVs) under pulsed DC fields, using a simple semi-analytical model. The coupled equations of electroporation,...
This work attempts to understand the mechanism of poration induced deformation in giant unilamellar vesicles (GUVs) under pulsed DC fields, using a simple semi-analytical model. The coupled equations of electroporation, electrohydrodynamics, and membrane mechanics are solved within the limit of small deformations. The excess membrane area, generated by electroporation, is assumed to manifest as amplitudes of higher-order shape deformation modes, thereby resulting in prolate or oblate cylindrical or square shapes. The origin of these higher modes is essentially due to electropore-induced, polar angle-dependent membrane conductance. The model qualitatively and semi-quantitatively, with a correction factor (fitting parameter) though, captures the square shape modes for = 1, prolate ellipsoids (cylinders) for > 1, and oblate cylinders for < 1, where = / is the ratio of the electrical conductivity of the inner fluid () to that of the outer fluid ().
Light-tunable DNA interactions enable spatiotemporal assembly and relaxation-driven crystallization of colloids.
Ducrot E, Hage PA, van Ravensteijn BGP … +2 more , Pine DJ, Voets IK
Soft Matter · 2026 Jun · PMID 42171201 · Full text
Self-assembly of colloidal particles enables the formation of complex superstructures, yet precise control over assembled structures remains challenging and assembly pathways primarily rely on temperature, a global trigg...
Self-assembly of colloidal particles enables the formation of complex superstructures, yet precise control over assembled structures remains challenging and assembly pathways primarily rely on temperature, a global trigger. Here, we introduce a strategy to dynamically modulate DNA-mediated colloidal interactions using azobenzene-functionalized DNA strands (azoDNA) grafted on colloidal particles, programming the interaction landscapes in space and time. Photo-isomerization of the azobenzene moiety allows reversible and continuous tuning of the stability of DNA duplexes, enabling light-controlled regulation of interparticle binding under isothermal conditions. By varying illumination conditions, the effective melting temperature of the colloids can be adjusted over a wide range, allowing reversible assembly, spatially patterned aggregation, and dynamic reconfiguration of colloidal structures at the scale of a few particles. Beyond reversible switching, we show that the slow thermal relaxation of azobenzene provides a new route to relaxation-mediated colloidal crystallization, in which the gradual recovery of DNA stickiness promotes ordered crystal growth. These results demonstrate how light can be used to program both the strength and the temporal evolution of DNA-mediated interactions, offering a versatile platform for spatiotemporally controlled self-assembly and adaptive colloidal materials.
A supramolecular gel platform for selective naked-eye recognition of thorium(IV) ion.
He Y, Yu XQ, Yu S
Soft Matter · 2026 May · PMID 42171194 · Publisher ↗
The naked-eye detection of Th poses a critical analytical challenge. While stimulus-responsive hydrogels offer a potential solution by converting recognition events into visible macroscopic phase transitions, this promis...
The naked-eye detection of Th poses a critical analytical challenge. While stimulus-responsive hydrogels offer a potential solution by converting recognition events into visible macroscopic phase transitions, this promising mechanism has not been specifically explored for Th. We demonstrate a supramolecular hydrogel platform using a 1,1'-binaphthyl derivative (BINAB). BINAB hydrogel forms through the self-assembly of molecules into a 3D fibrous network hydrogen bonding and π-π stacking, with the resulting network confining the solvent to induce gelation. The gel exhibits thorium-induced collapse and displays high specificity toward Th. Mechanism studies indicate that the recognition involves the terminal carboxyl groups of BINAB forming a 1 : 1 complex with Th, whereby this high-affinity interaction triggers selective precipitation and disintegration of the gel network, enabling specific and naked-eye recognition of Th among 24 metal ions.
Influence of rigid-soft domains on proton conduction and microstructure in block copolymer membranes.
Kumar A, Chang DW
Soft Matter · 2026 May · PMID 42171188 · Publisher ↗
In ionic copolymers, chemically distinct domains can be combined to enhance proton transport and stability. In this work, we integrated a rigid engineering plastic, poly(ether ether ketone) (PEEK), with phosphonated poly...
In ionic copolymers, chemically distinct domains can be combined to enhance proton transport and stability. In this work, we integrated a rigid engineering plastic, poly(ether ether ketone) (PEEK), with phosphonated polystyrene chains to fabricate membranes containing complementary rigid and soft molecular domains. The rigid PEEK chains provided thermal stability and mechanical integrity, while the flexible phosphonated polystyrene domains enabled proton conduction under anhydrous or low-humidity conditions. The resulting membranes exhibited a proton conductivity approaching 10 S cm at 50% relative humidity and 1 bar vapor pressure. Structural analysis revealed planar, porous surfaces and supported the role of proton hopping as the dominant conduction mechanism, with activation energies in the range of 0.08-0.50 eV. These findings highlight how rigid-soft molecular design can balance stability and conductivity, making such membranes promising candidates for use as separators in hydrogen or methanol fuel cells.
Dynamic permeability in metastable droplet interfacial bilayers.
Sarma NA, King DA, Wu X … +4 more , Helms BA, Ashby PD, Russell TP, Omar AK
Soft Matter · 2026 Jun · PMID 42171117 · Publisher ↗
Membrane pores are implicated in several critical functions, including cell fusion and the transport of signaling molecules for intercellular communication. However, these structural features are often difficult to probe...
Membrane pores are implicated in several critical functions, including cell fusion and the transport of signaling molecules for intercellular communication. However, these structural features are often difficult to probe directly. Droplet interfacial bilayers offer a synthetic platform to study such membrane properties. We develop a theory that links size-selective transport across a metastable membrane with its transient structural properties. The central quantity of our theory is a dynamic permeability that depends on the mechanism of pore growth, which controls the transient distribution of pore sizes in the membrane. We present a mechanical perspective to derive pore growth dynamics and the resulting size distribution for growth Ostwald ripening and discuss how these dynamics compare to other growth mechanisms such as coalescence and growth through surfactant desorption. We find scaling relations between the transported particle size, the pore growth rate, and the time for a given fraction of particles to cross the membrane, from which one may deduce the dominant mechanism of pore growth, as well as material properties and structural features of the membrane. Finally, we suggest experiments using droplet interfacial bilayers to validate our theoretical predictions.
Overview: the Janus-nature of molecular CO in charge adjustment at wet surfaces.
Vogel P, Qaisrani MN, Rasenat M … +5 more , Lützenkirchen J, Sulpizi M, Beyer D, Holm C, Palberg T
Soft Matter · 2026 Jun · PMID 42171115 · Publisher ↗
Molecular CO readily dissolves in aqueous electrolyte solutions and partially dissociating to form carbonic acid. The decharging effects of the dissociation products mediated by the ensuing pH-shift and the additional sa...
Molecular CO readily dissolves in aqueous electrolyte solutions and partially dissociating to form carbonic acid. The decharging effects of the dissociation products mediated by the ensuing pH-shift and the additional salinity are well established. However, the effects of dissolved molecular CO have not been studied systematically. We summarize recent and novel investigations on the role of CO regarding charge control at surfaces submersed in aqueous electrolytes. In our electrokinetic and conductometric measurements on representative surfaces, we took special care to control and monitor the electrolyte composition . We discriminate the effects of molecular and dissociated CO control experiments using HCl. Depending on the surface under investigation and the charging mechanisms involved, we find that molecular CO assists either charging, de-charging and/or recharging. This contrasting charge regulating behaviour reveals the Janus nature of dissolved molecular CO with respect to charge control at wet surfaces. In our complementary molecular dynamics simulations, Q4 silica and 9% ionized Q3 silica surfaces are studied as hydrophobic/hydrophilic, respectively charged/uncharged, analogues, as well as uncharged Q3 silica and molecularly rough Isoleucin-coated quartz surfaces. In all cases, we find that the charge-neutral CO molecule physisorbs in a thin diffusive layer close to the surface, which leads to pronounced re-structuring of the electric double layer. Based on this result, we suggest to interpret the experimentally observed Janus nature of molecular CO in terms of a local decrease of the dielectric permittivity. This in turn leads to a local strengthening of electrostatic interactions dominating the double layer structure next to charged surfaces. Specifically, we propose that CO induces a dielectric charge regulation for weakly acidic surface groups, assists the incorporation of OH into the H-bond network at smooth inert surfaces, and induces significant ion-correlations promoting co-ion binding. Overall, we demonstrate that molecular CO allows for a controlled charge-adjustment in opposing directions. We anticipate that our findings on the one hand provide substantial challenges for analytical or numerical modelling as well as for controlled experimental work, but on the other hand bear important practical implications for applications ranging from desalination to bio-membranes.
Plasticization as a tool for tuning the dynamics of polymerized ionic liquids: insights from molecular dynamics simulations.
Ahmad A, Vogel M
Soft Matter · 2026 Jun · PMID 42171111 · Publisher ↗
Using molecular dynamics simulations, we show that the dynamical properties of a polymerized ionic liquid (PIL), which features backbone-embedded imidazolium rings, can be tuned by plasticization with a simple ionic liqu...
Using molecular dynamics simulations, we show that the dynamical properties of a polymerized ionic liquid (PIL), which features backbone-embedded imidazolium rings, can be tuned by plasticization with a simple ionic liquid (SIL). Our structural analysis reveals a basically linear dependence of the local ionic environments on the PIL : SIL ratio. Moreover, we observe that the self diffusion coefficients and structural relaxation times vary continuously between the limiting cases of the pure PIL and pure SIL when changing the mixing ratio. Thereat, the concentration dependence is well described by the Gordon-Taylor equation. Upon cooling, and exhibit non-Arrhenius temperature dependence, while the Stokes-Einstein prediction ∝ is fulfilled to a high degree for all compositions. PIL-SIL mixing does not result in enhanced dynamical heterogeneity and leads to similar changes in the motions of the non-polymerized cations and anions, suggesting strong dynamical couplings between these constituents. Finally, Nernst-Einstein estimates of the room-temperature dc conductivity are reasonably high and amount to ∼10-10 S cm even at ∼25-50% PIL fractions. We conclude that electrolytes with favorable and tunable transport properties can be obtained from SIL plasticization of PILs, in particular, when the polymeric component has backbone-embedded charges.
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