Faculty of Advanced Life Science, Global Station for Soft Matter, Global Institution for Collaborative Research and Education (GSS, GI-CoRE), Hokkaido University, Kita-21 Nishi-11, Kita-ku, Sapporo, 001-0021, Japan.
Graduate School of Life Science, Hokkaido University, Kita-21 Nishi-11, Kita-ku, Sapporo, 001-0021, Japan.
Adv Mater. 2020 Jan;32(4):e1905878. doi: 10.1002/adma.201905878. Epub 2019 Nov 18.
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. By the cooperative effects of hydrophobic interaction and ionic interaction, the hydrogels undergo significant spinodal decomposition and subsequent rubbery-to-glassy transition when heated to an elevated temperature. As a result, the gels exhibit super-rapid and significant hikes in stiffness, strength, and toughness by up to 1800-, 80-, and 20-folds, respectively, when the temperature is raised from 25 to 70 °C, while the volumes of the gels are almost unchanged. As a potential application, the performance of the materials as athletic protective gear is demonstrated. This work provides a pathway for developing thermally stiffened materials and may significantly broaden the scope of polymer applications.
嗜热生物的蛋白质在高温环境中具有热稳定性，它们采用在高温疏水环境中增强静电相互作用的策略。受耐热蛋白质的分子机制启发，本文报道了一类新型聚合物材料的合成，该材料在高温下可超快速、等容和可逆地从软水凝胶转变为硬塑料。这些材料是由含有醋酸钙的多功能、廉价且无毒的聚丙烯酸水凝胶开发而成。通过疏水相互作用和离子相互作用的协同作用，水凝胶在加热到高温时会发生显著的旋节分解，随后发生橡胶态到玻璃态的转变。结果，当温度从 25°C 升高到 70°C 时，凝胶的刚度、强度和韧性分别提高了 1800 倍、80 倍和 20 倍，而凝胶的体积几乎不变。作为一种潜在的应用，本文展示了该材料作为运动防护装备的性能。这项工作为开发热增强材料提供了一种途径，并可能显著拓宽聚合物应用的范围。
