氧化石墨烯、粘土纳米复合水凝胶的研究与制备

【作者】 李志强；

【导师】 叶明新；

【作者基本信息】 复旦大学 ， 材料学， 2013， 硕士

【摘要】 水凝胶基于其优异的溶胀/消溶胀特性、对外界刺激的响应性及生物相容性,使其不仅在日常生活中得到了广泛的应用,而且在药物传输、化学分离等方面也有着良好的应用前景。但是,由于传统水凝胶较差的机械性能,很大程度上限制了水凝胶的应用。因此,如何提高水凝胶的机械性能已经成为近年来科学界的一个具有挑战性的重要课题。本文主要以无机粘土、表面改性氧化石墨烯(GO)作为为交联剂,分别制备了具有较好机械性能的半互穿聚合物网络(semi-IPN)水凝胶；在此基础上制备了双网络(DN)纳米复合水凝胶。主要研究工作如下：1.分别以改性锂皂石(Laponite XLS,粘土S)作为交联剂,N-异丙基丙烯酰胺(NIPAM)作为单体,海藻酸钠(SA)和四氧化三铁(Fe304)作为添加剂,采用原位自由基聚合的方法制备了一系列聚(N-异丙基丙烯酰胺)(PNIPAM)/SA/粘土/Fe3O4(NC水凝胶)多重响应的半互穿网络纳米复合水凝胶,与传统的有机交联水凝胶(OR水凝胶)相比,NC水凝胶具有较高的机械性能及溶胀度。2.首先通过氧化法制备了GO,然后用γ-甲基丙烯酰氧丙基三甲氧基硅烷(TMSPMA)对GO进行表面改性；并以TMSPMA改性GO作为交联剂,NIPAM作为单体,SA作为添加剂,成功制备了一系列PNIPAM/SA/GO双重响应的半互穿网络纳米复合水凝胶。与传统水凝胶相比,PNIPAM/SA/GO水凝胶不仅具有较高的机械性能,而且具有较快的溶胀/消溶胀速率,对温度的敏感性也大为增强。3.在以上研究的基础上,本节进一步采用无机GO作为添加剂,首先,通过原位自由基聚合的方法,以NIPAM作为单体,有机物N，N’-亚甲基双丙烯酰胺(BIS)为交联剂制备了单网络的PNIPAM传统水凝胶；然后,将其静置于一定浓度的丙烯酸(AA)水溶液中浸泡48h达到溶胀平衡；最后,通过紫外光引发的方法制备了一系列’NIPAM/AA/GO双网络纳米复合水凝胶。实验结果表明,PNIPAM/AA/GO水凝胶的溶胀/消溶胀速率明显好于传统水凝胶的溶胀/消溶胀速率,并且随着外界温度的升高,PNIPAM/AA/GO水凝胶的消溶胀速率会逐渐加快。更为重要的是,PNIPAM/AA/GO水凝胶的机械性能远远好于传统水凝胶,GO的加入与双网络结构的引进都在很大程度上提高了PNIPAM/AA/GO水凝胶的机械性能。更多还原

【Abstract】 Hydrogels with excellent swelling/deswelling, responsiveness to external stimuli and biocompatibility properties have not only been widely used in our daily life, but also a good application prospect in drug delivery, chemical separation and so on. However, conventional polymeric hydrogels crosslinked by organic crosslinkers are usually mechanically weak, limiting the application of hydrogels to some extent. So, in recent years, finding a way to overcome this limitation and enhance the hydrogels has become a challenging problem in the scientific community. In the present paper, semi-interpenetrating polymer network (semi-IPN) and double network (DN) organic/inorganic nanocomposite hydrogels with excellent mechnical properties are prpepared by using inorganic clay or inorganic graphene oxide (GO) as crosslinker. The main work is as follows:1. pH-and temperature-responsive semi-IPN magnetic nanocomposite hydrogels (NC hydrogels) were prepared by using linear sodium alginate (SA), N-isopropylacrylamide (NIPAM) as monomer, Fe3O4nanoparticles as additive and inorganic clay as an effective multifunctional crosslinker. The effects of crosslinker and SA contents on various physical properties were investigated. Comparing with conventional chemically hydrogels crosslinked by N,N’-methylenebisacrylamide (BIS), the NC hydrogels exhibit high swelling ratios and good mechanical property.2. GO sheets were first prepared via an oxidation reaction in aqueous solution and then modified with3-(trimethoxysilyl)propylmethacrylate (TMSPMA) via the silanization. pH-and temperature-responsive semi-IPN nanocomposite hydrogels (PNIPAM/SA/GO hydrogel) with surface-functionalized GO as the crosslinker, NIPAM as the monomer and sodium alginate (SA) as an additive. The effects of crosslinker and SA contents on various physical properties were investigated. Comparing with conventional chemically hydrogels crosslinked by organic BIS, the PNIPAM/SA/GO hydrogels exhibit high swelling ratios and good mechanical property.3. On the basis of above studies, we prepared pH-and temperature-responsive DN hydrogels (PNIPAM/AA/GO hydrogel) with poly(N-isopropylacrylamide)(PNIPAM) as a tightly crosslinked1st network, poly(acrylic acid)(PAA) as a loosely crosslinked2nd network and graphene oxide (GO) as an additive. GO sheets were first prepared via an oxidation reaction and then dispersed in NIPAM aqueous solution via the silanization. Free-radical polymerization of NIPAM was carried out at20℃in a water bath, and then subjected to UV light, leading to the formation of pH-and temperature-responsive PNIPAM/AA/GO DN hydrogels. The effects of GO sheets and AA contents on various physical properties were investigated. Comparing with conventional chemically hydrogels crosslinked by organic BIS, the PNIPAM/AA/GO hydrogels exhibit fast deswelling and good mechanical property.更多还原