Tough Double-Network Gels and Elastomers from the Nonprestretched First Network.

Double-network (DN) gels and elastomers, which consist of two (or more) rubbery polymer networks with contrasting physical properties, have received significant attention as they are extremely tough soft materials. The first network of tough DN materials should be more brittle and weaker than the second network. In this paper, we re-examined the structural requirements of the covalently cross-linked first network of tough DN materials and established a nonprestretching strategy.

Instant Thermal Switching from Soft Hydrogel to Rigid Plastics Inspired by Thermophile Proteins.

Proteins of thermophiles are thermally stable in a high-temperature environment, adopting a strategy of enhancing the electrostatic interaction in hydrophobic media at high temperature. Herein, inspired by the molecular mechanism of thermally stable proteins, the synthesis of novel polymer materials that undergo ultrarapid, isochoric, and reversible switching from soft hydrogels to rigid plastics at elevated temperature is reported. The materials are developed from versatile, inexpensive, and nontoxic poly(acrylic acid) hydrogels containing calcium acetate.