Previously, we prepared a tough nanocomposite interpenetrating hydrogel by chemical crosslinking of acrylamide (AM) with vinyl-modified silica nanoparticles (VSNPs), combined with physical crosslinking of polyvinyl alcohol (PVA). It is well-known that posttreatment method and molecular weight play important roles in the mechanical properties of the tough hydrogels. In this paper, different post-treatment methods, i.e., freeze-thaw and annealing-swelling and varying PVA degree of polymerization (500 and 1700) were used to prepare the nanocomposite interpenetrating hydrogels. The effects of posttreatment and PVA molecular weight on the mechanical and swelling properties were investigated in detail. Tensile tests showed that annealing-swelling process exerted a more pronounced influence on elevating the tensile strength of nanocomposite interpenetrating hydrogels, which arose from the increased crystallization degree of PVA and the denser network. Hydrogels with lower PVA molecular weight have higher tensile strength after freeze-thaw cycle than that with higher PVA molecular weight. Cyclic loading–unloading tests revealed that the gels with lower molecular weight of PVA can dissipate higher energy at 100% strain. The swelling kinetic study revealed that the swelling behaviors of nanocomposite interpenetrating hydrogels followed the pseudo-second-order dynamic equation.

中文翻译：

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具有高韧性的纳米复合互穿水凝胶：后处理和分子量的影响

此前，我们通过丙烯酰胺 (AM) 与乙烯基改性二氧化硅纳米粒子 (VSNPs) 的化学交联，结合聚乙烯醇 (PVA) 的物理交联制备了一种坚韧的纳米复合互穿水凝胶。众所周知，后处理方法和分子量对坚韧水凝胶的机械性能起着重要作用。在本文中，不同的后处理方法，即冻融和退火溶胀和不同的 PVA 聚合度（500 和 1700）被用来制备纳米复合互穿水凝胶。详细研究了后处理和 PVA 分子量对机械和溶胀性能的影响。拉伸试验表明，退火-溶胀过程对提高纳米复合互穿水凝胶的拉伸强度产生更显着的影响，这是由于 PVA 结晶度增加和网络更致密所致。与具有较高PVA分子量的水凝胶相比，具有较低PVA分子量的水凝胶在冻融循环后具有更高的拉伸强度。循环加载-卸载测试表明，具有较低分子量 PVA 的凝胶可以在 100% 应变下耗散更高的能量。溶胀动力学研究表明，纳米复合互穿水凝胶的溶胀行为遵循伪二阶动力学方程。具有较低 PVA 分子量的水凝胶在冻融循环后比具有较高 PVA 分子量的水凝胶具有更高的拉伸强度。循环加载-卸载测试表明，具有较低分子量 PVA 的凝胶可以在 100% 应变下耗散更高的能量。溶胀动力学研究表明，纳米复合互穿水凝胶的溶胀行为遵循伪二阶动力学方程。与具有较高PVA分子量的水凝胶相比，具有较低PVA分子量的水凝胶在冻融循环后具有更高的拉伸强度。循环加载-卸载测试表明，具有较低分子量 PVA 的凝胶可以在 100% 应变下耗散更高的能量。溶胀动力学研究表明，纳米复合互穿水凝胶的溶胀行为遵循伪二阶动力学方程。