Soft matter roadmap^*

Abstract

Soft materials are usually defined as materials made of mesoscopic entities, often self-organized, sensitive to thermal fluctuations and to weak perturbations. Archetypal examples are colloids, polymers, amphiphiles, liquid crystals, foams. The importance of soft materials in everyday commodity products, as well as in technological applications, is enormous, and controlling or improving their properties is the focus of many efforts. 

From a fundamental perspective, the possibility of manipulating soft material properties, by tuning interactions between constituents and by applying external perturbations, gives rise to an almost unlimited variety in physical properties. Together with the relative ease to observe and characterize them, this renders soft matter systems powerful model systems to investigate statistical physics phenomena, many of them relevant as well to hard condensed matter systems.
 
Understanding the emerging properties from mesoscale constituents still poses enormous challenges, which have stimulated a wealth of new experimental approaches, including the synthesis of new systems with, e.g., tailored self-assembling properties, or novel experimental techniques in imaging, scattering or rheology. Theoretical and numerical methods, and coarse-grained models, have become central to predict physical properties of soft materials, while computational approaches that also use machine learning tools are playing a progressively major role in many investigations.

This roadmap paper intends to give a broad overview of recent and possible future activities in the field of soft materials, with experts covering various developments and challenges in material synthesis and characterization, instrumental, simulation and theoretical methods as well as general concepts.

Thermoresponsive oil-continuous gels based on double-interpenetrating colloidal-particle networks

“…Due to its ubiquity, addressing fundamental questions about the origin of the colloidal gel state and elucidating the interplay between structure and internal dynamics is crucial for controlling the properties of soft materials. 1 These materials are found in ceramics, films, cosmetics, paints and coatings, pharmaceuticals, foods, etc. 1 Several routes to colloidal gelation have been proposed.…”

“…1 These materials are found in ceramics, films, cosmetics, paints and coatings, pharmaceuticals, foods, etc. 1 Several routes to colloidal gelation have been proposed. These include non-equilibrium kinetic arrest via spinodal decomposition, kinetic arrest based on competing short-range attractive depletion and long-range electrostatic repulsion, equilibrium arrest induced by highly anisotropic and limited interactions, and other combinations of aggregation pathways.…”

“…These include non-equilibrium kinetic arrest via spinodal decomposition, kinetic arrest based on competing short-range attractive depletion and long-range electrostatic repulsion, equilibrium arrest induced by highly anisotropic and limited interactions, and other combinations of aggregation pathways. 1–3…”

“…17 Despite their potential, these systems also present significant challenges, including the need for novel synthesis routes, production in larger quantities, exquisite geometry and surface design to control interactions, anisotropic non-uniform packing, slow gelation, non-uniform stress distribution, among other considerations. 1,14,18…”

Modeling the Temperature-Dependent Size Change of Polydisperse Nano-objects using a Deep Generative Model

“…The group of soft materials ranges from colloids and polymers to gels, liquids, and biomaterials and has become a high-profile research topic due to its many important applications. − Microgels are an interesting class of soft materials as they combine properties of colloids, polymers and large-scale gels . Especially the volume phase transition of microgels is a largely spread research topic with continuously increasing importance. − With their soft and cross-linked polymer network, microgels may hold for various applications attributed to their property to adsorb molecules and particles inside their inner structure and release them again under controllable conditions. − Depending on the building blocks used, external stimuli, such as temperature, pH, or ionic strength, change the microgel volume and polymer density drastically.…”