Abstract The poly(N-isopropylacrylamide-co-N-maleylgelatin) [P(NIPAAm-co-N-MAGEL)] hydrogel was prepared by the free radical polymerization of N-isopropylacrylamide (NIPAAm) and N-maleylgelatin (N-MAGEL) with N,N′-methylene bis(acrylamide) (BIS) as the cross linker in the complete aqueous environment. The hydrogel becomes opaque when the temperature exceeds lower critical solution temperature (LCST) and goes back to its original transparent state when it is cooled below the LCST which can be finely tuned as it shows a linear dependence on the concentration of Na+, Mg2+ and Al3+. Interestingly, different from Na+ and Mg2+, Al3+ could mediate the transparency of the hydrogel even when the temperature is below LCST and induce the formation of double-network (DN) hydrogel. Metal-ion-carboxylate supramolecular interactions are proposed to dominate this property through ionic cross-linking. The hydrogel could be used as the temperature and metal ions controlled smart window. Effects of metal ions on swelling characteristics, mechanical property and microstructures of the hydrogel were further investigated.

中文翻译：

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用于智能窗户的具有热响应性的金属离子介导的水凝胶

摘要 通过 N-异丙基丙烯酰胺 (NIPAAm) 和 N-马来酰明胶 (N-MAGEL) 的自由基聚合制备了聚 (N-异丙基丙烯酰胺-co-N-马来酰明胶) [P(NIPAAm-co-N-MAGEL)] 水凝胶。 N,N'-亚甲基双（丙烯酰胺）（BIS）作为完全水性环境中的交联剂。当温度超过下临界溶解温度 (LCST) 时，水凝胶变得不透明，当它冷却到 LCST 以下时，水凝胶会恢复到原来的透明状态，这可以进行微调，因为它显示出对 Na+、Mg2+ 和 Al3+ 浓度的线性依赖性. 有趣的是，与 Na+ 和 Mg2+ 不同，即使温度低于 LCST，Al3+ 也可以调节水凝胶的透明度并诱导双网络 (DN) 水凝胶的形成。金属-离子-羧酸盐超分子相互作用被提议通过离子交联来支配该特性。水凝胶可用作温度和金属离子控制的智能窗口。进一步研究了金属离子对水凝胶溶胀特性、力学性能和微观结构的影响。