Interpenetrating polymer networks (IPNs) have emerged as innovative materials for a wide range of applications. Owing to the crosslinked structure of their polymer components, IPNs exhibit superior properties relative to their single component counterparts. Here, we report a new class of multifunctional graft-interpenetrating polymer network (graft-IPN) hydrogel composites of poly(-isopropylacrylamide) (PNIPAM) grafted onto cellulose nanofibers (CNFs) silver(I)-promoted decarboxylative polymerization. This novel approach involves the Ag-promoted graft polymerization and the crosslinking of PNIPAM in the CNF network, forming a hybrid of semi-IPN and graft-copolymer hydrogel. Different from conventional PNIPAM-CNF IPNs, the CNFs in graft-IPN hydrogels form an interconnected network as a result of crosslinking between neighboring grafted PNIPAM. Silver nanoparticles (AgNPs) are also formed in the graft-IPN hydrogel matrix, demonstrating the dual functionality of silver as both a catalyst in the polymerization and an eventual antibacterial agent in the hydrogel. The network structure of graft-IPN hydrogels can be controlled by crosslinker and Ag(I) concentration, therefore modulating their thermo-responsive, mechanical, and swelling properties. The grafting of PNIPAM from CNFs shifts the volume phase transition to 36 °C and significantly improves the mechanical strength and swelling capacity of the hydrogels. Ultimately, this work demonstrates the excellent potential of these multifunctional graft-IPN hydrogels with controllable thermosensitivity, mechanical strength and anti-microbial activity as engineered biomaterials for advanced applications in biomedicine, engineering, and industry.

中文翻译：

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通过银促进脱羧自由基聚合纤维素纳米纤维和聚（N-异丙基丙烯酰胺）的多功能接枝-IPN水凝胶

互穿聚合物网络 (IPN) 已成为具有广泛应用的创新材料。由于其聚合物组分的交联结构，IPN 相对于单组分同类产品表现出优异的性能。在这里，我们报道了一种新型多功能接枝互穿聚合物网络（接枝-IPN）水凝胶复合材料，其由聚（异丙基丙烯酰胺）（PNIPAM）接枝到纤维素纳米纤维（CNF）上，银（I）促进脱羧聚合。这种新方法涉及Ag促进的接枝聚合和CNF网络中PNIPAM的交联，形成半IPN和接枝共聚物水凝胶的混合体。与传统的 PNIPAM-CNF IPN 不同，接枝 IPN 水凝胶中的 CNF 由于相邻接枝 PNIPAM 之间的交联而形成互连网络。接枝-IPN 水凝胶基质中也形成了银纳米颗粒 (AgNP)，这证明了银的双重功能，即既作为聚合反应的催化剂，又作为水凝胶中的最终抗菌剂。接枝 IPN 水凝胶的网络结构可以通过交联剂和 Ag(I) 浓度来控制，从而调节其热响应、机械和溶胀性能。从 CNF 接枝 PNIPAM 将体积相变转移至 36 °C，并显着提高了水凝胶的机械强度和溶胀能力。最终，这项工作证明了这些具有可控热敏性、机械强度和抗菌活性的多功能接枝-互穿网络水凝胶作为工程生物材料在生物医学、工程和工业中的高级应用的巨大潜力。