Acrylamide-based hydrogels usually have a random distribution of characteristic functional groups on the molecular chain due to differences in monomer reactivity ratios, resulting in an inhomogeneous polymer network. This inhomogeneity leads to severely inadequate mechanical properties, limiting their application in load-bearing fields. This study delineates a novel approach to synthesize homogeneous hydrogels with enhanced mechanical strength, heightened energy dissipation capacity, and superior impact resistance, termed partially hydrolyzed polymer hydrogels (HP hydrogel). The methodology involves the partial hydrolysis of polyacrylamide in an alkaline environment to convert amide groups into carboxylate groups, followed by the introduction of Fe3+ ions to establish a ligand network through coordination bonding. This partial hydrolysis technique significantly augments the homogeneity of the coordination network. The carboxylate-Fe3+ coordination bonds introduce an efficient energy dissipation mechanism, which is pivotal in enhancing the mechanical robustness of the hydrogels. Comparative analysis reveals that HP hydrogels exhibit mechanical properties substantially superior to those of conventional poly(acrylamide-co-acrylic acid) copolymer hydrogels (CP hydrogel). Notably, the tensile strength of HP hydrogels is quadruple that of CP hydrogels, reaching up to 7.0 MPa, while maintaining the same carboxylic acid content. Furthermore, HP hydrogels demonstrate remarkable tear and impact resistance, evidenced by a fracture energy of 7.5 kJ/m2 in notched specimens and an 85.7 % enhancement in impact resilience. The strategic partial hydrolysis not only improves the homogeneity of the gel structure but also instills a robust energy dissipation mechanism, thereby significantly fortifying the comprehensive mechanical properties of the hydrogels. This advancement potentially broadens the applicability of acrylamide hydrogels in load-bearing and other mechanically demanding environments.

中文翻译：

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坚固、对缺口不敏感且抗冲击的物理水凝胶，通过部分水解和金属配位实现均匀拓扑网络


由于单体反应率的差异，基于丙烯酰胺的水凝胶通常在分子链上具有特征官能团的随机分布，从而导致聚合物网络不均匀。这种不均匀性导致机械性能严重不足，限制了它们在承重领域的应用。本研究描述了一种合成具有增强机械强度、更高能量耗散能力和卓越抗冲击性的均质水凝胶的新方法，称为部分水解聚合物水凝胶 （HP 水凝胶）。该方法涉及聚丙烯酰胺在碱性环境中部分水解，将酰胺基团转化为羧酸盐基团，然后引入 Fe3+ 离子，通过配位键建立配体网络。这种部分水解技术显着增强了配位网络的均匀性。羧酸盐-Fe3+ 配位键引入了一种有效的能量耗散机制，这对于增强水凝胶的机械稳健性至关重要。比较分析表明，HP 水凝胶表现出的机械性能大大优于传统的聚丙烯酰胺-共丙烯酸）共聚物水凝胶 （CP 水凝胶）。值得注意的是，HP 水凝胶的拉伸强度是 CP 水凝胶的四倍，最高可达 7.0 MPa，同时保持相同的羧酸含量。此外，HP 水凝胶表现出卓越的抗撕裂性和抗冲击性，缺口试样的断裂能量为 7.5 kJ/m2，冲击回弹性提高了 85.7%。 战略性的部分水解不仅提高了凝胶结构的均匀性，而且还灌输了强大的能量耗散机制，从而显着增强了水凝胶的综合机械性能。这一进步可能拓宽了丙烯酰胺水凝胶在承重和其他机械要求环境中的适用性。