Smart material

Abstract: Shape-engineerable and highly densely packed single-walled carbon nanotubes and their application as super-capacitor electrodes

Abstract: Interest in stimuli-responsive polymers has persisted over many decades, and a great deal of work has been dedicated to developing environmentally sensitive macromolecules that can be crafted into new smart materials. However, the overwhelming majority of reports in the literature describe stimuli-responsive polymers that are sensitive to only a few common triggers, including changes in pH, temperature, and electrolyte concentration. Herein, we aim to highlight recent results and future trends that exploit stimuli that have not yet been as heavily considered, despite their unique potential. Many of the topics represent clear opportunities for making advances in biomedical fields due to their specificity and the ability to respond to stimuli that are inherently present in living systems. Recent results in the area of polymers that respond to specific antigen–antibody interactions, enzymes, and glucose are specifically discussed. Also considered are polymeric systems that respond to light, electric, magnetic, and sonic fields, all of which have potential in the area of controlled release as a result of their ability to be applied in a non-invasive and easily controlled manner. Thiol-responsive and redox-responsive polymers are also highlighted, with particular attention being devoted to their reversible dynamic covalent chemistry. It is our goal to emphasize these underutilized adaptive behaviors so that novel applications and new generations of smart materials can be realized.

Abstract: Shape-memory polymers (SMPs) undergo significant macroscopic deformation upon the application of an external stimulus (e.g., heat, electricity, light, magnetism, moisture and even a change in pH value). They have been widely researched since the 1980s and are an example of a promising smart material. This paper aims to provide a comprehensive review of SMPs, encompassing a fundamental understanding of the shape-memory effect, fabrication, modeling and characterization of SMPs, various actuation methods and multifunctional properties of SMP composites, and potential applications for SMP structures. A definition of SMPs and their fundamentals are first presented. Next, a description of their fabrication, characterization and constitutive models of SMPs are introduced. SMP composites, which act to improve a certain function as functional materials or the general mechanical properties as structural materials, are briefly discussed. Specially, the SMP composites can be developed into multifunctional materials actuated by various methods, such as thermal-induced, electro-activated, light-induced, magnetic-actuated and solution-responsive SMPs. As smart materials, the applications of SMPs and their composites receive much interest, including deployable structures, morphing structures, biomaterials, smart textiles and fabrics, SMP foams, automobile actuators and self-healing composite systems.

Abstract: Magnetorheological (MR) fluids, foams and elastomers comprise a class of smart materials whose rheological properties may be controlled by the application of an external magnetic field. MR fluids are liquids whose flow or shear properties are easily controlled to enable a variety of unique torque transfer or vibration control devices. MR foams, in which the controllable fluid is contained in an absorptive matrix, provide a convenient way of realizing the benefits of MR fluids in highly cost sensitive applications. MR elastomers are solid, rubber-like materials whose stiffness may be controlled to provide tunable or adjustable mounts and suspension devices.

Abstract: In this review a strategy for the design of bioinspired, smart, multiscale interfacial (BSMI) materials is presented and put into context with recent progress in the field of BSMI materials spanning natural to artificial to reversibly stimuli-sensitive interfaces. BSMI materials that respond to single/dual/multiple external stimuli, e.g., light, pH, electrical fields, and so on, can switch reversibly between two entirely opposite properties. This article utilizes hydrophobicity and hydrophilicity as an example to demonstrate the feasibility of the design strategy, which may also be extended to other properties, for example, conductor/insulator, p-type/n-type semiconductor, or ferromagnetism/anti-ferromagnetism, for the design of other BSMI materials in the future.