Stretching-induced ion complexation in physical polyampholyte hydrogels
Stretching-induced ion complexation in physical polyampholyte hydrogels
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DOI：
10.1039/c6sm01833e
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发表时间：
2016-01-01
期刊：
影响因子：
3.4
通讯作者：
Gong, Jian Ping
中科院分区：
文献类型：
--
作者：
Cui, Kunpeng;Sun, Tao Lin;Gong, Jian Ping
近年来，我们通过在水中无规共聚的方法开发了一系列电荷平衡型聚两性聚合物（PA）物理水凝胶，这些水凝胶具有非常高的韧性、自愈能力和粘弹性。PA水凝胶的优异性能归因于通过链间和链内相互作用形成的动态离子键。随机性导致离子键强度分布较宽，强键作为永久交联，赋予弹性，而弱键可逆断裂和重新形成，耗散能量。在这项工作中，我们开发了一种简单的物理方法，称为预拉伸法，以提高PA水凝胶的性能。通过在制备状态下对样品施加预拉伸，透析过程中的离子络合明显加快，最终性能大大提高。进一步分析表明，预拉伸引起的强键形成是导致最终性能变化的原因。预拉伸降低了体系的熵，增加了链的排列，从而增加了形成强键的可能性。
Recently, we have developed a series of charge balanced polyampholyte (PA) physical hydrogels by random copolymerization in water, which show extraordinarily high toughness, self-healing ability and viscoelasticity. The excellent performance of PA hydrogels is ascribed to dynamic ionic bond formation through inter-and intra-chain interactions. The randomness results in ionic bonds of wide strength distribution, the strong bonds, which serve as permanent crosslinking, imparting the elasticity, while the weak bonds reversibly break and re-form, dissipating energy. In this work, we developed a simple physical method, called a pre-stretching method, to promote the performance of PA hydrogels. By imposing a pre-stretching on the sample in the as-prepared state, ion complexation during dialysis is prominently accelerated and the final performance is largely promoted. Further analysis suggests that the strong bond formation induced by pre-stretching is responsible for the change in final performance. Pre-stretching decreases the entropy of the system and increases the chain alignment, resulting in an increased possibility for strong bond formation.