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Mechanical enhancement of hydrophobically associating hydrogels by solvent-regulated phase separation
Polymer ( IF 4.1 ) Pub Date : 2020-09-16 , DOI: 10.1016/j.polymer.2020.123042
Wei Cui , Yifeng Cai , Yong Zheng , Rong Ran

Hydrogels have a wide range of potential applications due to their unique soft and hydrated structure. Many applications, however, require an efficient combination of mechanical properties including strength, stiffness, toughness, and viscoelasticity, which is rarely achieved. In this work, we report the simultaneously strengthening, stiffening, and toughening of a conventionally weak gel, hydrophobically associating hydrogel, by a simple regulation of external solvent. Phase separation is induced when the hydrogel is immersed into the mixed solvent that has a relatively high concentration of a poor solvent, resulting in the increment of polymer volume fraction in the gel. As a result, strong inter/intra polymer interactions emerge at the nanoscale, which serve the role of sacrificial bonds to dissipate large amounts of energy. The phase-separated, viscoelastic hydrogel exhibits significant enhancements in strength, stiffness, and toughness by up to 270-, 9200-, and 2500-folds, respectively, exceeding a great many tough hydrogels. Periodically changing the solvent enables the reversible phase-separation process, facilitating the regulation of mechanical properties of the hydrogel upon demand. This solvent-regulated phase-separation strategy, due to its facile procedure, repeatability, and high efficiency, offers a universal guideline to toughen weak hydrogels.



中文翻译:

通过溶剂调节相分离机械增强疏水缔合水凝胶

水凝胶由于其独特的柔软和水合结构而具有广泛的潜在应用。然而,许多应用需要有效地结合机械性能,包括强度,刚度,韧性和粘弹性,而这是很难实现的。在这项工作中,我们报告了通过外部溶剂的简单调节,传统上较弱的凝胶(疏水缔合水凝胶)的同时增强,硬化和增韧。当将水凝胶浸入具有相对较高浓度的不良溶剂的混合溶剂中时,会引起相分离,从而导致凝胶中聚合物体积分数的增加。结果,在纳米级出现了强大的内部/内部聚合物相互作用,这起到了牺牲键的作用,以耗散大量能量。相分离 粘弹性水凝胶的强度,刚度和韧性分别显着提高了270倍,9200倍和2500倍,大大超过了许多坚韧的水凝胶。周期性地改变溶剂能够进行可逆的相分离过程,从而有利于根据需要调节水凝胶的机械性能。由于其易于操作,可重复性和高效率,这种溶剂调节的相分离策略可为增韧弱水凝胶提供通用指导。根据需要促进调节水凝胶的机械性能。由于其易于操作,可重复性和高效率,这种溶剂调节的相分离策略可为增韧弱水凝胶提供通用指导。根据需要促进调节水凝胶的机械性能。由于其易于操作,可重复性和高效率,这种溶剂调节的相分离策略可为增韧弱水凝胶提供通用指导。

更新日期:2020-09-22
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