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Liquid foams are concentrated dispersions of gas bubbles in a small amount of surfactant solution, which are perpetually out of equilibrium systems. The process of liquid draining through networks of Plateau borders in a fresh foam is so-called foam drainage, as a result of both gravitational and capillary forces, which has great effect on the stability of foams. From the view of foam physics and dynamics, this paper briefly introduces foam structure and major lifetime limiting factors of foam. The substantial progress on the theory of drainage, measuring techniques for liquid fractions, drainage in both one dimension and two dimensions, and drainage in microgravity circumstances are overviewed throughout. Remaining tasks are discussed and a multiscale methodology for foam drainage is proposed for future investigations.

In this paper, we review some recent achievements in thermal metamaterials, including novel thermal devices, simplified experimental method, macroscopic thermal diode based on temperature-dependent transformation thermotics, and the important role that soft matters play in the experimental confirmations of thermal metamaterials. These works pave the developments in transformation mapping theory and can surely inspire more designs of thermal metamaterials. What is more, some approaches provide more flexibility in controlling heat flow, and they may also be useful in other fields that are closely related to temperature gradient, such as the Seebeck effect and many other domains where transformation theory is valid.

The field-induced soft smart materials are a kind of soft matter whose macroscopic properties (mechanical, or optical) can be significantly and actively controlled and manipulated by external fields such as magnetic field, electric field, temperature or light. In this paper, we briefly review the research and application progress of the field-induced soft smart materials in recent years and discuss the development problems and trend in this research area. In particular, we focus on three typical field-induced soft materials of smart materials: magnetorheological fluid, electrorheological fluid, and temperature and light sensitive polymer gel.

An experimental approach is employed by using transparent electrodes to investigate the column size distribution where an external electric field applied to a colloidal suspension is increased. The coarsening profile of ER suspension is strongly related to field strength, but is insensitive to particle size. In addition, the interaction among the suspended particles, i.e. the shear stress, corresponding to the mean column diameter is studied and the power-law dependence is found at low field range. However, this dependence is not valid when the field strength surpasses a threshold value.

The hydrodynamic model for soft-matter quasicrystals with 14-fold symmetry is investigated. The 14-fold symmetry soft-matter quasicrystals belong to the second kind of soft-matter quasicrystals. The most distinction between the first and the second kinds of the soft-matter quasicrystals lies in the four elementary excitations including two phason elementary excitations exist for the latter. The equations of motion for point group 14 mm soft-matter qusicrystals are given, and an initial-boundary value problem of the equations is solved by applying the finite difference method. The effects of the phonons, first phasons, second phasons, fluid phonon and their interactions in space-time domain are explored.

The study of optical spatial solitons in nematic liquid crystals (NLC) has greatly improved the understanding of light localization in reorientational nonlocal media. We report some of the latest progress with reference to bright and dark solitary waves in NLC, bright and dark nematicons, discussing models and methods for their description and simulation. We give an account of exact and approximate solutions, as well as nematicon bistability.

In reorientational soft-matter with uniaxial character, such as nematic liquid crystals (NLCs), self-confined beams into spatial optical solitons are graded-index waveguides subject to birefringent walkoff. We investigate a router to be realized in a planar cell with an inhomogeneous distribution of the optic axis. Based on the input beam position, the proposed demultiplexer can direct the soliton and the copolarized guided-wave signal(s) to various output ports, enhancing the transverse separation of the exit channels and therefore minimizing crosstalk. Both the soliton and the signal(s) maintain their phasefronts normal to launch and exit wavevectors, allowing for excellent coupling into output channels/fibers at the device exit.

A highly nonlocal optical response in space has been shown to heal several shortcomings of beam self-action in nonlinear optics. At the same time, nonlocality is often connected to limits and constraints in both temporal and spatial domains. We provide a brief and rather subjective review of what we consider the main benefits and some drawbacks of a highly nonlocal response in light localization through nonlinear optics, with several examples related to reorientational soft matter, specifically nematic liquid crystals.

Computer simulations and in particular mesoscopic simulation techniques such as the dissipative particle dynamics (DPD) technique, enable researchers to study the complexities of soft material and polymeric systems by performing in silico experimentations alongside in vivo experiments. In addition, these mesoscopic simulations allow scientists and engineers to characterize and optimize the actual experiments in a more efficient manner. The DPD is one the most reliable mesoscopic simulation techniques for phenomenological investigation of soft matter and polymeric systems. In this review, which is complimentary to an earlier review also by the present authors on DPD methodology and complex fluid application (Moeendarbary et al., 2009), we categorize and review the notable published works, and document efforts that applied the DPD simulation technique to various important soft matter and polymeric applications, over the last decade.

Micro- and nano-scale hydrogel lines can be fabricated on substrates by top-down approaches such as lithography and micro/nano-imprint. When in contact with a solvent, the hydrogel lines swell under the constraint of the substrate, often resulting in distorted shapes or instability patterns. In this paper, using a nonlinear finite element method, the effects of material and geometry on swell-induced instability of substrate-attached hydrogel lines are studied. Firstly, with a two-dimensional plane-strain model, we show that crease-like surface instability occurs in hydrogel lines with the width-to-height aspect ratio greater than a critical value. Next, for relative low aspect ratios, we show that a global buckling instability occurs. In both cases, the critical conditions depend on the material parameters that characterize the elastic stiffness of the polymer network and the chemical interaction between solvent and polymer in the hydrogel.

Morphogenesis is a result of complex biological, chemical, and physical processes in which differential growth in biological systems is a common phenomenon, especially notable in plant organs such as petals and leaves. Mechanisms of these biologic structures have been studied in recent years with a growing focus from the mechanics point of view. However, understanding differential-growth-induced shape formation quantitatively in plant organs remains largely unknown. In this study, we conduct quantitative experimental measurement, theoretical analysis, and sufficient finite element analysis of constrained differential growth of a thin membrane-like structure. By deriving the corresponding strain energy expression of a buckled growing sample, we can calculate the shape function of such membrane structures explicitly. The results of this work demonstrate the effect of growth function, geometry characteristics, and material property. Our research points to potential approaches to novel geometrical design and inspirations on the microscale and the macroscale for items such as soft robotics and flexible electronics.

Going down the particle size to nanodomain opens up innovative allies to expedite the physical and chemical properties of materials, and in turn, facilitates the manipulation of their catalytic propensity. Herein, we provide a succinct perspective of the wide spectrum of nanoparticles (NPs) in catalysis highlighting the underlying chemistry of different aspects, the introspective thread connecting them, and the ways to devise operando algorithms for exploiting such inter-connected systems. Following an introductory section discussing the generic miens of NPs, we went on to discuss the role of nanocrystals, especially various crystal facets and morphological anomalies in catalysis. The electronic shuttling involved in these catalysis vis-à-vis surface plasmon effect, Mott–Schottky contact, and Z-scheme systems, all in the nanodomain, was then explained. Following this, we introduced the concept of “Soft Matter” and “Active Matter”, essentially the ones exploiting previously discussed chemistry, and explained the role of their in situ morphological precedence and stimuli-induced motility in catalysis. Finally, the emerging concept of Operando Systems Chemistry Algorithm (OSCA) was instituted discussing the devising strategies of tandem compartmentalized chemical arrays as individual algorithm analogs to sequentially impact the properties of aforementioned soft and active matters for targeted catalytic assays.