Zhang Jing Wen, Dong Dian Dian, Guan Xiao Yu, Zhang En Mian, Chen Yong Mei, Yang Kuan, Zhang Yun Xia, Khan Malik Muhammad Bilal, Arfat Yasir, Aziz Yasir
College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science & Technology, Xi'an, China.
National Demonstration Center for Experimental Light Chemistry Engineering Education (Shaanxi University of Science & Technology), Xi'an, China.
Front Chem. 2020 Mar 10;8:102. doi: 10.3389/fchem.2020.00102. eCollection 2020.
Tough gel with extreme temperature tolerance is a class of soft materials having potential applications in the specific fields that require excellent integrated properties under subzero temperature. Herein, physically crosslinked Europium (Eu)-alginate/polyvinyl alcohol (PVA) organohydrogels that do not freeze at far below 0°C, while retention of high stress and stretchability is demonstrated. These organohydrogels are synthesized through displacement of water swollen in polymer networks of hydrogel to cryoprotectants (e.g., ethylene glycol, glycerol, and d-sorbitol). The organohydrogels swollen water-cryoprotectant binary systems can be recovered to their original shapes when be bent, folded and even twisted after being cooled down to a temperature as low as -20 and -45°C, due to lower vapor pressure and ice-inhibition of cryoprotectants. The physical organohydrogels exhibit the maximum stress (5.62 ± 0.41 MPa) and strain (7.63 ± 0.02), which is about 10 and 2 times of their original hydrogel, due to the synergistic effect of multiple hydrogen bonds, coordination bonds and dense polymer networks. Based on these features, such physically crosslinked organohydrogels with extreme toughness and wide temperature tolerance is a promising soft material expanding the applications of gels in more specific and harsh conditions.
具有极端温度耐受性的坚韧凝胶是一类软材料，在需要在零下温度下具有优异综合性能的特定领域具有潜在应用。在此，展示了一种物理交联的铕（Eu）-海藻酸盐/聚乙烯醇（PVA）有机水凝胶，其在远低于0°C的温度下不会冻结，同时保留了高应力和拉伸性。这些有机水凝胶是通过将水凝胶聚合物网络中溶胀的水置换为冷冻保护剂（例如乙二醇、甘油和d-山梨醇）来合成的。由于冷冻保护剂的较低蒸气压和抑冰作用，当冷却至低至-20°C和-45°C的温度后，溶胀有水-冷冻保护剂二元体系的有机水凝胶在弯曲、折叠甚至扭曲后仍可恢复到其原始形状。由于多重氢键、配位键和致密聚合物网络的协同作用，物理有机水凝胶表现出最大应力（5.62±0.41MPa）和应变（7.63±0.02），分别约为其原始水凝胶的10倍和2倍。基于这些特性，这种具有极端韧性和宽温度耐受性的物理交联有机水凝胶是一种有前途的软材料，可在更特殊和苛刻的条件下扩展凝胶的应用。
