温度及pH敏感黄原胶/PNIPAAm凝胶的制备及性能研究

【作者】 隆清德；

【导师】 潘春跃；

【作者基本信息】 中南大学 ， 有机化学， 2008， 硕士

【摘要】 环境敏感性水凝胶在药物控制释放、酶的固载化及生物物质分离提纯等方面有着诱人的应用前景。本文在总结前人大量工作的基础上,从分子设计的角度出发提出并尝试将具有优良温敏性的聚（N-异丙基丙烯酰胺）（PNIPAAm）与具有良好生物相容性和在药物控释有应用潜力的黄原胶结合起来,合成了两种不同类型的温度和pH双重敏感的水凝胶,采用红外光谱（IR）、示差扫描量热法（DSC）等手段对合成产物的结构进行了表征,系统地研究了这类凝胶的温度和pH敏感性能,并对其溶胀、消溶胀性能及响应机理进行了探讨,取得了以下主要研究结果:（1）以N,N-二甲基甲酰胺（DMF）为溶剂,将具有双官能团的顺丁烯二酸酐引入到天然高分子黄原胶分子上,从FTIR结果显示,顺丁烯二酸酐成功地接枝上黄原胶C6位置。（2）采用半互穿网络技术（semi-IPN）制备了一类新型Xanthan/PNIPAAm半互穿网络水凝胶,对这类水凝胶的温度及pH敏感行为进行了详细的研究。实验结果表明,去离子水和缓冲溶液（pH=2.2和pH=7.4）中semi-IPN水凝胶溶胀度均随着Xanthan含量增加溶胀度逐渐增加;随着温度的升高,Xanthan/PNIPAAm semi-IPN水凝胶都表现出典型的“热缩型”温敏特性。同时Xanthan/PNIPAAmsemi-IPN水凝胶有明显的pH敏感性。Xanthan/PNIPAAm半互穿网络水凝胶的溶胀与退胀性能与黄原胶的含量有较大关系,分析认为是具有螺旋刚性结构的黄原胶为凝胶网络中水分的吸收与排出提供了“通道”。但是Xanthan分子对凝胶的最低临界溶解温度（LCST）改变不大。（3）通过自由基聚合,制备了一类接枝改性黄原胶与NIPAAm共聚水凝胶（Xan-MA/PNIPAAm）。研究发现,共聚水凝胶的环境响应性能,溶胀、退胀性能与Xanthan/PMPAAm semi-IPN水凝胶相似,但是Xan-MA/PNIPAAm中前驱体的质量比对凝胶的LCST有较大影响,可以通过调节m_Xan-MA:m_PNIPAAm来调节共聚凝胶的LCST。更多还原

【Abstract】 In recent years, considerable research attention has been focused on the environment-sensitive hydrogels because of they possess great potential applications in many aspects, including drug delivery system, enzyme immobilization and biomaterials separation purification, etc. From the point of view of molecule design, a series of novel type of temperature and pH responsive hydrogels was prepared based on the poly（N-isopropylacrylamide） （PNIPAAm） and a natural material xanthan （Xan） with a good biocompatibility in this dissertation. Two different types of dual temperature and pH sensitive hydrogels were synthesized, and the structures of the product were characterized by infrared spectroscopy （IR）, differential scanning calorimetry （DSC）. The effect of the feeds composition on the swelling and deswelling properties of these hydrogels has been systematically studied, and the swelling, deswelling behavior and response mechanism was discussed. The main results obtained are as follows:a) N, N-dimethylformamide （DMF） as the solvent, a dual-functional group of maleic anhydride is programmed imported to the natural polymer xanthan elements, from FTIR results show that maleic anhydride successful grafted to xanthan C6 position.b) A kind of semi-IPN hydrogels based on xanthan and cross-linked poly（N-isopropylacrylamide） was prepared with semi-interpenetrating network （semi-IPN） technique. The swelling behaviors of the Xanthan/PNIPAAm semi-IPN hydrogel which sensitive to both temperature and pH, were investigated in detail. Results show swelling of the hydrogel in deionized water as well as in the buffer solution （pH = 2.2 and pH = 7.4） gradual increase with Xanthan compositon increase, Xanthan / PNIPAAm semi-IPN hydrogels have shown a typical "thermal-negative" thermo-sensitive properties. At the same time, Xanthan/PNIPAAm semi-IPN hydrogel show clear pH sensitivity. Swelling and deswelling property of Xanthan/PNIPAAm semi-IPN hydrogel related to the content of Xanthan which attribute to a spiral of rigid structure of xanthan providing a "Channel" led water in and out. But the addition of Xanthan has little impact on the critical solution temperature （LCST）.c) Through radical solution polymerization, a kind of grafting xanthan gum and NIPAAm copolymer hydrogel （Xan-MA/PNIPAAm） were synthesized, it was found that environmental responsive, swelling, and deswelling property of Xan-MA/PNIPAAm is similar with semi-IPN hydrogel, but the feed composition of Xan-MA/PNIPAAm in the precursor have a greater impact on the LCST, we can adjust proportion of m_Xan-MA:m_PNIPAAm to regulate the LCST of copolymer hydrogel.更多还原