Double network (DN) gels have remarkably high mechanical strength and toughness and can be potentially applied in biomedical applications such as cartilage regeneration. However, most DN gels synthesised by usual radical polymerisations are non-biodegradable, and they are not desirable for replacing living tissues in the human body. In this study, we developed a DN gel with polyelectrolyte stents (St-DN gel) that exhibited high mechanical strength and biodegradability under physiological conditions. These degradable St-DN gels were prepared using poly(N,N-dimetylacrylamide) (PDMAAm) as the second network and poly(ethylene glycol) (PEG) as the first network. The PEG gel contained the molecular stent and a degradable ester bond in its network strands. To prepare the degradable PDMAAm gel, we designed a hydrolysable cross-linking agent, PEG-di(methacryloyloxyethyl succinate) (PEG-DMOS), with six ester bonds. The obtained St-DN gel showed an extremely high compressive fracture strength and strain. We also confirmed that the St-DN gel could be gradually hydrolysed under physiological conditions. Thus, this hydrolysable high-strength gel could be potentially used as an implantable biomedical material.

中文翻译：

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使用可水解交联剂合成可降解双网络凝胶

双网络 (DN) 凝胶具有非常高的机械强度和韧性，可以潜在地应用于生物医学应用，例如软骨再生。然而，大多数通过通常的自由基聚合合成的 DN 凝胶是不可生物降解的，并且它们不适用于替代人体中的活组织。在这项研究中，我们开发了一种带有聚电解质支架的 DN 凝胶（St-DN 凝胶），它在生理条件下表现出高机械强度和可生物降解性。这些可降解的 St-DN 凝胶是使用 poly( N,N-二甲基丙烯酰胺）（PDMAAm）作为第二个网络，聚（乙二醇）（PEG）作为第一个网络。PEG凝胶在其网络链中包含分子支架和可降解的酯键。为了制备可降解的 PDMAAm 凝胶，我们设计了一种具有六个酯键的可水解交联剂 PEG-二(甲基丙烯酰氧基乙基琥珀酸酯) (PEG-DMOS)。得到的St-DN凝胶显示出极高的抗压断裂强度和应变。我们还证实了 St-DN 凝胶可以在生理条件下逐渐水解。因此，这种可水解的高强度凝胶可以潜在地用作可植入的生物医学材料。