机械训练自增强复合水凝胶的制备及性能研究

Preparation and properties of mechanically trained self-reinforced composite hydrogels

以2-甲基-2-丙烯酰胺基丙磺酸钠(NaAMPS)、聚乙烯醇(PVA)、羧甲基纤维素(CMC)作为原料,采用N,N′-亚甲基双丙烯酰胺作为交联剂,2-氧基戊二酸作为引发剂,紫外光引发NaAMPS化学交联形成凝胶第一重网络;采用循环冷冻-解冻方法使PVA链间通过氢键作用形成凝胶第二重网络;采用Al^(3+)与CMC的羧基之间的离子络合作用形成凝胶第三重网络,制备得到PNaAMPS/PVA/CMC-Al^(3+)复合水凝胶。对凝胶进行微观形貌表征、力学性能测试。结果表明:在形成第一、二重网络结构后,水凝胶内部网络变得更为致密,PVA间氢键的形成使凝胶的断裂强度由14kPa提升至53kPa;CMC-Al^(3+)的第三重网络形成后凝胶的断裂强度提升至127kPa。此外,将N-异丙基丙烯酰胺(NIPAM)作为预聚合单体加入凝胶中,凝胶在机械训练后表现出断裂应力自增强的效果,在机械训练应变为40%时,断裂强度提升23%,随着机械训练应变由40%增至160%,凝胶的断裂强度提升56%。该水凝胶通过机械训练诱导的结构破坏并重建过程实现了力学性能自增强,拓宽了在各领域中的实际应用,可为用于软机器人和智能设备等应用的自增强材料奠定基础。

Using 2-methyl-2-acrylamidopropanesulfonic acid sodium salt(NaAMPS),polyvinyl alcohol(PVA),and carboxymethyl cellulose(CMC)as raw materials,N,N′-methylene bisacrylamide as the cross-linking agent and 2-oxoglutaric acid as the initiator,the first network of the gel was formed by UV light triggered chemical cross-linking of NaAMPS.Cyclic freezing-thawing method was used to form the second network of the gel by hydrogen bonding between PVA chains.The third gel network was formed by ionic complexation between Al^(3+)and carboxyl groups of CMC,and the PNaAMPS/PVA/CMC-Al^(3+)composite hydrogel was successfully prepared.The microscopic morphologies of the gels were characterized and the mechanical properties of the gels were tested.The results showed that the internal network of the hydrogels became denser after the formation of the first and second networks,and the formation of hydrogen bonds between PVA chains increased the fracture strength from 14kPa to 53kPa.The formation of the third network of CMC-Al^(3+)increased the fracture strength to be 127kPa.In addition,N-isopropyl acrylamide(NIPAM)was added to the gel as a pre-polymerization monomer,and the gel exhibited a self-enhancement of fracture strength after mechanical training,with an enhancement of fracture strength of 23%at the mechanical training strain of 40%,and the fracture strength enhancement of 56%as the mechanical training strain increased from 40%to 160%.This hydrogel achieved the self-reinforcement of mechanical properties through the mechanical training-induced structural damage and reconstruction process,which broadened the practical applications in various fields and could lay the foundation for self-reinforced materials used in applications such as soft robots and smart devices.