基于动态共价键的pH响应自修复水凝胶的制备与评价

Synthesis and evaluation of self-healing pH-sensitive hydrogel based on dynamic covalent bond

以α-甲基丙烯酸(MAA)和2-丙烯酰胺-2-甲基丙磺酸(AMPS)的共聚物P(MAA/AMPS)及聚乙烯醇(PVA)为单体、十水合四硼酸钠为交联剂合成了P(MAA/AMPS)-PVA二重互穿网络的p H响应水凝胶。通过SEM、FTIR、GPC、TGA-DTG和流变仪等表征了水凝胶的表面形貌和化学状态;测定了水凝胶的溶胀性﹑p H响应性﹑自修复性和流变性。结果表明,水凝胶形成了稳定的互穿网络结构且具有pH敏感性、自修复性;PVA羟基与硼酸根离子形成的共价配位硼酸酯键使水凝胶具备自修复性并受介质酸碱性的控制;力学性能测定结果显示,自修复水凝胶(SB用量为2.5%,水凝胶溶胀度为4)拉伸强度668 kPa,断裂伸长率可达665%,修复效率可达81%。

Copolymer P(MAA/AMPS) of α-methacrylic acid(MAA) and 2-acrylamido-2-methyl propanesulfonic acid(AMPS) reacted with polyvinyl alcohol(PVA) in the crosslinking dosage of sodium tetraborate decahydrate to prepare double-interpenetrating network(semi-IPN) p H-sensitive hydrogels P(MAA/AMPS)-PVA. The surface morphology and chemical state of hydrogels were characterized by SEM,FTIR, GPC, TGA-DTG and rheometer. The swelling, pH-sensitive, self-healing and rheological properties of hydrogels were measured. The test results showed that the hydrogels formed a stable interpenetrating network structure and exhibited pH-sensitive and self-healing properties. The covalent coordination borate ester bond formed by PVA hydroxyl group and borate ion determined self-healing property of hydrogel and was controlled by the acid base of the medium. The mechanical experiment indicated that the self-healing hydrogel had a tensile strength of 668 kPa, an elongation at break of 665%, and a self-healing efficiency of 81% with the content of SB was 2.5%, the swelling degree of hydrogel was 4.