From theoretical aspects to practical food Pickering emulsions: Formation, stabilization, and complexities linked to the use of colloidal food particles.

We noticed that in literature, the term Pickering emulsion (PE) is used as soon as ingredients contain particles, and in this review, we ask ourselves if that is done rightfully so. The basic behavior taking place in particle-stabilized emulsions leads to the conclusion that the desorption energy of particles is generally high making particles highly suited to physically stabilize emulsions. Exceptions are particles with extreme contact angles or systems with very low interfacial tension.

Self-stratification and phase separation in drying binary colloidal films.

Hypothesis: Films that develop compositional heterogeneity during drying offer a promising approach for achieving tailored functionalities. These functionalities can be realized by strategically directing different components during the drying process. One approach to achieve this is through spontaneous size segregation of colloidal particles.

De novo DNA-based catch bonds.

All primary chemical interactions weaken under mechanical stress, which imposes fundamental mechanical limits on the materials constructed from them. Biological materials combine plasticity with strength, for which nature has evolved a unique solution-catch bonds, supramolecular interactions that strengthen under tension. Biological catch bonds use force-gated conformational switches to convert weak bonds into strong ones.

Moderated ionic bonding for water-free recyclable polyelectrolyte complex materials.

While nature extensively uses electrostatic bonding between oppositely charged polymers to assemble and stabilize materials, harnessing these interactions in synthetic systems has been challenging. Synthetic materials cross-linked with a high density of ionic bonds, such as polyelectrolyte complexes, only function properly when their charge interactions are attenuated in the presence of ample amounts of water; dehydrating these materials creates such strong Coulombic bonding that they become brittle, non-thermoplastic, and virtually impossible to process. We present a strategy to intrinsically moderate the electrostatic bond strengths in apolar polymeric solids by the covalent grafting of attenuator spacers to the charge carrying moieties.

3D printable soft and solvent-free thermoplastic elastomer containing dangling bottlebrush chains.

Polymer networks containing bottlebrush chains are emerging materials with exceptionally soft and highly tunable mechanical properties. However, such materials have not been extensively implemented in functional processing techniques such as three-dimensional (3D) printing. Here, we introduce a new design of soft and solvent-free polydimethylsiloxane (PDMS)-based thermoplastic elastomer which contains dangling and space-filling bottlebrush chains, featuring a yield stress and a rapid recovery after stress removal; both required for high spatial fidelity 3D printing.

Elongated particles discharged with a conveyor belt in a two-dimensional silo.

The flow of elliptical particles out of a two-dimensional silo when extracted with a conveyor belt is analyzed experimentally. The conveyor belt-placed directly below the silo outlet-reduces the flow rate, increases the size of the stagnant zone, and it has a very strong influence on the relative velocity fluctuations as they strongly increase everywhere in the silo with decreasing belt speed. In other words, instead of slower but smooth flow, flow reduction by belt leads to intermittent flow.

Quantitative imaging methods for heterogeneous multi-component films.

The drying of multi-component dispersions is a common phenomenon in a variety of everyday applications, including coatings, inks, processed foods, and cosmetics. As the solvent evaporates, the different components may spontaneously segregate laterally and/or in depth, which can significantly impact the macroscopic properties of the dried film. To obtain a quantitative understanding of these processes, high-resolution analysis of segregation patterns is crucial.

Spatially heterogenous dynamics in colloidal gels during syneresis.

Syneresis, the compaction of a material accompanied by fluid expulsion, is a typical mechanical instability which exists among colloidal gel based materials and that negatively affects the quality of relevant applications. We shed light onto the internal dynamics of model colloidal gels undergoing syneresis using Laser Speckle Imaging (LSI). The resulting dynamical maps capture the distinct differences in spatial and temporal relaxation patterns between colloidal gels comprising solid and liquid particles.

Cross-linker Mobility Governs Fracture Behavior of Catch-Bonded Networks.

While most chemical bonds weaken under the action of mechanical force (called slip bond behavior), nature has developed bonds that do the opposite: their lifetime increases as force is applied. While such catch bonds have been studied quite extensively at the single molecule level and in adhesive contacts, recent work has shown that they are also abundantly present as crosslinkers in the actin cytoskeleton. However, their role and the mechanism by which they operate in these networks have remained unclear.

Active microrheology of protein condensates using colloidal probe-AFM.

Protein condensates resulting from liquid-liquid phase separation have long been studied as bio-adhesives and coating materials for various applications. More recently, they are also being scrutinized as models for membraneless organelles in cells. Quantifying their interfacial mechanics and rheology at micrometer scales is vital for better understanding the physics underlying membraneless organelles in cells and for developing and improving technological applications of protein condensates.

In-situ and quantitative imaging of evaporation-induced stratification in binary suspensions.

The drying of a multi-component dispersion, such as water-based paint, ink and sunscreen to form a solid film, is a widespread process. Binary colloidal suspensions have proven capable of spontaneous layer formation through size segregation during drying. To design bespoke stratification patterns, a deeper understanding of how these emerge is crucial.

Synthesis of well-defined linear-bottlebrush-linear triblock copolymer towards architecturally-tunable soft materials.

Linear-bottlebrush-linear (LBBL) triblock copolymers are emerging systems for topologically-tunable elastic materials. In this paper, a new synthetic methodology is presented to synthesize LBBL polystyrene--bottlebrushpolydimethylsiloxane--polystyrene (PS--bbPDMS--PS) triblock copolymer the "grafting onto" approach where the precursors are individually synthesized through living anionic polymerization and selective coupling reaction. In this two-step approach, polystyrene--polymethylvinylsiloxane (PS--PMVS) diblock copolymer with a low dispersity couples with another living PS block to form PS--PMVS--PS triblock copolymer.

Force Transmission in Disordered Fibre Networks.

Cells residing in living tissues apply forces to their immediate surroundings to promote the restructuration of the extracellular matrix fibres and to transmit mechanical signals to other cells. Here we use a minimalist model to study how these forces, applied locally by cell contraction, propagate through the fibrous network in the extracellular matrix. In particular, we characterize how the transmission of forces is influenced by the connectivity of the network and by the bending rigidity of the fibers.

An actin mechanostat ensures hyphal tip sharpness in to achieve host penetration.

Filamentous plant pathogens apply mechanical forces to pierce their hosts surface and penetrate its tissues. Devastating pathogens harness a specialized form of invasive tip growth to slice through the plant surface, wielding their hypha as a microscopic knife. Slicing requires a sharp hyphal tip that is not blunted at the site of the mechanical interaction.

Stretchy and disordered: Toward understanding fracture in soft network materials via mesoscopic computer simulations.

Soft network materials exist in numerous forms ranging from polymer networks, such as elastomers, to fiber networks, such as collagen. In addition, in colloidal gels, an underlying network structure can be identified, and several metamaterials and textiles can be considered network materials as well. Many of these materials share a highly disordered microstructure and can undergo large deformations before damage becomes visible at the macroscopic level.

Large Scale Hydrodynamically Coupled Brownian Dynamics Simulations of Polymer Solutions Flowing through Porous Media.

Large scale simulations of polymer flow through porous media provide an important tool for solving problems in enhanced oil recovery, polymer processing and biological applications. In order to include the effects of a wide range of velocity and density fluctuations, we base our work on a coarse-grain particle-based model consisting of polymers following Brownian dynamics coupled to a background fluid flow through momentum conserving interactions. The polymers are represented as Finitely Extensible Non-Linear Elastic (FENE) dumbbells with interactions including slowly decaying transient forces to properly describe dynamic effects of the eliminated degrees of freedom.

Sharing the Load: Stress Redistribution Governs Fracture of Polymer Double Networks.

The stress response of polymer double networks depends not only on the properties of the constituent networks but also on the interactions arising between them. Here, we demonstrate, via coarse-grained simulations, that both their global stress response and their microscopic fracture mechanics are governed by load sharing through these internetwork interactions. By comparing our results with affine predictions, where stress redistribution is by definition homogeneous, we show that stress redistribution is highly inhomogeneous.

Core-Shell Microcapsules from Unpurified Legume Flours.

Plant-based ingredients are key building blocks for future sustainable advanced materials. Functionality is typically higher for highly purified plant-based ingredients, but this is at the expense of their sustainability value. Here, a method is introduced for creating a soft functional material, with structural elements ranging from the nanometer to the millimeter scale, directly from legume flours.

A slicing mechanism facilitates host entry by plant-pathogenic Phytophthora.

Phytophthora species, classified as oomycetes, are among the most destructive plant pathogens worldwide and pose a substantial threat to food security. Plant pathogens have developed various methods to breach the cuticle and walls of plant cells. For example, plant-pathogenic fungi use a 'brute-force' approach by producing a specialized and fortified invasion organ to generate invasive pressures.

Single-Step Application of Polyelectrolyte Complex Films as Oxygen Barrier Coatings.

Polyelectrolyte complex (PEC) films such as polyelectrolyte multilayers have demonstrated excellent oxygen barrier properties, but unfortunately, the established layer-by-layer approaches are laborious and difficult to scale up. Here, we demonstrate a novel single-step approach to produce a PEC film, based on the use of a volatile base. Ammonia was used to adjust the pH of poly(acrylic acid) (PAA) so that direct complexation was avoided when it was mixed with polyethylenimine (PEI).

Long-term single-cell imaging and simulations of microtubules reveal principles behind wall patterning during proto-xylem development.

Plants are the tallest organisms on Earth; a feature sustained by solute-transporting xylem vessels in the plant vasculature. The xylem vessels are supported by strong cell walls that are assembled in intricate patterns. Cortical microtubules direct wall deposition and need to rapidly re-organize during xylem cell development.

The role of temperature in the rigidity-controlled fracture of elastic networks.

We study the influence of thermal fluctuations on the fracture of elastic networks, via simulations of the uniaxial extension of central-force spring networks with varying rigidity. Studying their failure response, both at the macroscopic and microscopic level, we find that an increase in temperature corresponds to a more homogeneous stress (re)distribution and induces thermally activated failure of springs. As a consequence, the material strength decreases upon increasing temperature, the microscopic damage spreads over a larger area and a more ductile fracture process is observed.

Propagation and attenuation of mechanical signals in ultrasoft 2D solids.

The propagation of elastic waves in soft materials plays a crucial role in the spatiotemporal transmission of mechanical signals, e.g., in biological mechanotransduction or in the failure of marginal solids.