In this brief review, an introduction of the underlying mechanisms for the shape memory effect (SME) and various shape memory phenomena in polymers is presented first. After that, a summary of typical applications in sensors based on either heating or wetting activated shape recovery using largely commercial engineering polymers, which are programmed by means of in-plane pre-deformation (load applied in the length/width direction) or out-of-plane pre-deformation (load applied in the thickness direction), is presented. As demonstrated by a number of examples, many low-cost engineering polymers are well suited to, for instance, anti-counterfeit and over-heating/wetting monitoring applications via visual sensation and/or tactual sensation, and many existing technologies and products (e.g., holography, 3D printing, nano-imprinting, electro-spinning, lenticular lens, Fresnel lens, QR/bar code, Moiré pattern, FRID, structural coloring, etc.) can be integrated with the shape memory feature.

Self‐healing polymer is a kind of intelligent material with the capability to repair damage automatically. In this paper, a type of polyurethane containing carboxyl groups is reported that demonstrates thermally assisted healing effects. This polymer can be healed even 72 h after cutting and also has a repeatable healing property. The self‐healing efficiency can reach 90% when comparing the tensile strength of the healed sample to the original sample. Carboxyl content plays an important role in the self‐healing property; polyurethane with no carboxyl groups cannot be healed. The mechanism of self‐healing showed that hydrogen bonding interactions between carboxyl groups and diffusion of poly(ethylene glycol) chains contribute to the self‐healing behavior. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45929.

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Water as a common, easily obtained, and environmentally friendly stimulus has been explored in stimuli-responsive materials. In this paper, a series of composites, named as PVA­(n)-CMC­(m)-GA, were prepared by filling the carboxymethyl cellulose sodium (CMC) into chemical cross-linked poly­(vinyl alcohol) (PVA). These composites demonstrated both water induced shape memory and self-healing effect. CMC with water sensitivity help the composite absorbing water to decrease the T g of composite to cause shape recovery. And CMC with water solubility is also a good healing agent, which can freely move across the cutting cross-section in wet condition and form hydrogen bonds with PVA chains in dry condition to achieve healing. Water can affect the hydrogen bonding interactions between CMC and PVA, and which play a key role in the water-stimuli responsive properties. This study provides a relatively simple and low cost way to obtain water-induced multifunction materials.

A series of silicone based elastic shape memory hybrids are fabricated. Their shape memory performance, mechanical behaviors at room temperature with/without programming and during fitting at 37 • C are investigated. It is found that these materials have good shape memory effect and are always highly elastic. At 37 • C, there are 10 min or more for fitting. Thus, it is concluded that this type of material has great potential as an elastic shape memory material for comfort fitting.

The shape memory effect (SME) refers to the ability of a material to recover its original shape, but only in the presence of a right stimulus. Most polymers, either thermo-plastic or thermoset, can have the SME, although the actual shape memory performance varies according to the exact material and how the material is processed. Vitrimer, which is between thermoset and thermo-plastic, is featured by the reversible cross-linking. Vitrimer-like shape memory polymers (SMPs) combine the vitrimer-like behavior (associated with dissociative covalent adaptable networks) and SME, and can be utilized to achieve many novel functions that are difficult to be realized by conventional polymers. In the first part of this paper, a commercial polymer is used to demonstrate how to characterize the vitrimer-like behavior based on the heating-responsive SME. In the second part, a series of cases are presented to reveal the potential applications of vitrimer-like SMPs and their composites. It is concluded that the vitrimer-like feature not only enables many new ways in reshaping polymers, but also can bring forward new approaches in manufacturing, such as, rapid 3D printing in solid state on space/air/sea missions.

Conidia of Beauveria bassiana Bb-202, which have the potential for the control of the coleopteran pests, were produced on rice by solid-state fermentation (SSF) using tray bioreactor. As the solid substrate thickness increased, the production of conidia decreased. By cutting substrate into many small uniform pieces, metabolic heat and gas transfer in center of substrate could be improved. We concluded that the highest yield of 3.94×1012 conidia kg-1 rice was obtained as the substrate of 2cm thickness was cut into many small pieces (6cm×4cm×2cm). And the average yield of conidia increases by 45%. It indicated that cut solid substrate into many pieces would increasing the surface area of substrate. So the conidia yields were significantly increased.

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