Themed collection 2021 Soft Matter Emerging Investigators

This themed collection of Soft Matter highlights the work of emerging investigators in the field of soft matter. Editor-in-Chief Darrin Pochan introduces the issue.

The use of hydrogels has garnered significant interest as biomaterial and drug delivery platforms for anti-infective applications.

Lipid membranes envelope live cells and mediate vital biological functions through regulated spatiotemporal dynamics. This review highlights the role of neutron scattering, among other approaches, in uncovering the dynamic properties of lipid membranes.

Properties of supramolecular nanostructures are mediated by conformational, exchange, and water dynamics. Here we review experimental methods and recent reports of dynamics characterization of small molecule nanomaterials.

Physical models can help us to infer, from the shape of the outer membrane, which biological processes happen inside the living cell.

Engineered living materials integrate genetic engineering and synthetic materials to program stimuli responses that enable the fabrication of devices for diverse applications.

Electrohydrodynamics is among the most promising techniques for manipulating liquids in microsystems.

We discover a new regime in which the extensibility of bottlebrush polymer networks is inversely proportional to the network stiffness.

Generalized mode-coupling theory, a first-principles-based theory, systematically improves the prediction of phase diagrams for sticky hard spheres.

The adsorption of solid particles on the surface of solubilizing oil droplets can significantly enhance the droplets’ self-propulsion speeds.

Unique observations of cutting energy in silicone elastomers motivate a picture of soft fracture that qualitatively and quantitatively links far-field tearing with push cutting for the first time.

We study quasi two-dimensional, monodisperse systems of active Brownian particles (ABPs) for a range of activities, stiffnesses, and densities.

We find the aqueous PEO–SDS mixtures show a significantly weaker concentration-dependent variation in the extensional relaxation time, filament lifespan, and extensional viscosity values than anticipated by the shear viscosity vs. concentration plots.

Small amounts of transmembrane peptides can significantly alter the collective dynamics in lipid membranes even when there are no changes in the average membrane structure.

In vitro reconstitutions of lipid membranes can contain residual hydrophobic solvents. We investigate the influence of residual solvents on lipid bilayers properties using Molecular Dynamics simulations.

Owing to the local/heterogeneous structures in supercooled liquids, after several decades of research, it is now clear that supercooled liquids are structurally different from their conventional liquid counterparts.

Biomimetic vesicle prototissues have been designed as a model for cellular tissues. Prototissues display spheroidal or sheet like morphologies, and have predictable vesicle–vesicle adhesion strengths, typical sizes, and degree of compaction.

We describe a straightforward way to determine the poroelastic diffusion coefficient of a hydrogel particle by first indenting it via swelling in a granular packing, and then monitoring how its indented shape relaxes after it is removed.

We report a transient twist observed in common thermotropic, achiral liquid crystals at the transition between the smectic and the nematic phase. This is explained with the combined effect of the change of the elastic constants at the phase transition and of the confining geometry.

When a soft elastic body impacts upon a smooth solid surface, the intervening air fails to drain, deforming the impactor. High-speed imaging with the VFT reveal rich dynamics and sensitivity to the impactor's elastic properties and the impact velocity.

When adhesive emulsions are flowed in 2D constrictions, their local rearrangements are impaired, leading to higher deformations. The adhesive emulsions are globally more aligned in the direction of elongation, leading to a global polarization.

Using evanescent wave microscopy to study near-surface, semi-dilute polymer solution flows provides simultaneous access to the mechanical behaviour of the liquid and the boundary condition at the interfaces. Our results highlight the importance of electrostatic interactions between the polymers and the bounding wall.

We study dynamic reshaping of lipid vesicles under osmotic shocks via molecular dynamics simulations. We identified rich morphology transformations, and observed a separation of time scales between the shock absorption and the shape relaxation.

Via a simple elastic swimmer actuated magnetically, we present a first study to examine how shear-thinning rheology impacts the fluid-structure interaction and hence the elastohydrodynamic propulsion performance at low Reynolds numbers.

Performing large-scale simulations of active particles and employing finite-size-scaling analysis, we provide exhaustive evidence that motility-induced critical point belongs to the Ising universality class.

Antioxidant polysulfide nanoparticles can be electrospun within nanofibre scaffold patches to provide anti-inflammatory action.

Negative osmotic pressure drives non-equilibrium phase separation of “reversible” colloidal gels subjected to weak external stress, manifesting as yield under fully intact network.

Using experiments and modeling, we study the spontaneous wrapping of a negatively charged microfiber around a positively charged disk-shaped particle immersed in a liquid.

We describe, characterise and explain emerging heterogeneity of red bolood cell partitioning within a network substantially deviating from empirical predictions.

Onsager's variational principle is extended and applied to the dynamic modeling of active soft matter such as the directional motion of individual self-propelled units and the dynamics of active polar droplets on solid substrates.

Nanoconfining scaffolds can be used to orient and shape organic semiconductor crystals during solution-phase crystallization depending on the scaffold geometry and the native crystal growth habit.

A coarse-grained model for analysis and design of hybrid DNA-protein nanoscale structures.

We propose a new tracking-free method for the quantification of multiscale dynamics in 2D and 3D cell collectives.

Wetting in a nearly rectangular channel.

A drying multi-component liquid droplet in a confined geometry leaves a uniform dried pattern. The evaporated vapors are stagnated inside the closed chamber, which induce Marangoni effects that contribute to suppress the coffee-ring pattern.

Magnetic actuation has emerged as a powerful and versatile mechanism for diverse applications, ranging from soft robotics, biomedical devices to functional metamaterials.

Dynamic networks with precise spacers between boronic ester bonds were investigated over a broad temperature window. Arrhenius behavior breaks down and an increase in relaxation time is observed when approach the glass transition temperature.

We show that the Plateau–Rayleigh instability can be suppressed by the interfacial self-assembly and crosslinking of nanoparticles, potentially introducing a new approach for additive manufacturing.

We show deterministic control of adhesive crack initiation, propagation, and arresting by integrating a granular jamming layer into adhesive films.

In situ polymer grafting from the mid-block of an ABA triblock copolymer leads to morphology transitions and enhanced mechanical properties.

A complex, three-stage fracture process is described for hydrogels, resulting in material failure. This process is markedly different than that observed in brittle materials, and we describe how this process varies with network architecture.

A method for changing the salt and polymer concentrations of coacervates independently is developed and used to investigate their rheology.

Optical quantification of intracellular mass density using optical diffraction tomography (ODT) and cell mechanics using Brillouin spectroscopy under 3D mechanical confinement.

The adhesion of rough surfaces comprised of dewetted thermoplastic asperities on an elastomer is controlled by changing the applied compressive load.

Biological cells have long been of interest to researchers due to their capacity to actively control their shape.

Characterization of N-phenylmaleimide-terminated poly(ethylene glycol)s and their application to a tetra-arm poly(ethylene glycol) gels

A wide range of proteins create shape transformations of membranes. The remodeling is a coupling between the energetic cost of membrane bending, protein recruitment which induce local spontaneous curvature and protein diffusion on the membrane.

To improve the understanding of phototaxis, we investigate the origin of our photocatalytic particles’ peculiar scotophobicity (fear of darkness).

Free-energy landscape of crystallized syndiotactic-polystyrene polymorphism from quantum-mechanical calculations and coarse-grained simulations.

Protic ionic liquids (PILs) are the largest and most tailorable known class of non-aqueous solvents which possess the ability to support amphiphile self-assembly.

A systematic study of the effect of metal–ligand interactions on the viscoelastic properties of the reversible polymer networks.

We introduce graph theory measures and demonstrate how transitions in microstructural conformations can be quantified and correlated to the rheology.

We developed a new type of visible-range photothermal microscopy for measurement of optical absorption with excellent spatial resolution.

We measured by neutron reflectometry the loss of asymmetry in solid supported lipid bilayers, revealing an intrinsic interplay between passive lipid flip-flop and lipid phase transition.

The cytoskeleton, a complex network of protein filaments and crosslinking proteins, dictates diverse cellular processes ranging from division to cargo transport.

(Right) Optical micrograph (TRITC–Phalloidin) of a fibroblastoid cell. (Left) Configuration obtained from theoretical model using the adhesion sites of the experimental data as input.