温度/pH敏感性壳聚糖-聚乙烯吡咯烷酮水凝胶的制备

Preparation of Thermo-Sensitive/pH-Sensitive Chitosan/Polyvinylpyrrolidone Hydrogels

以壳聚糖(CS)和聚乙烯基吡咯烷酮(PVP)为原料,戊二醛为交联剂,硝酸铈铵为引发剂,制备了具有温度和pH双重敏感性的CS/PVP水凝胶。考察了制备条件对水凝胶溶胀率的影响,结果表明,在PVP∶CS(质量比)=10∶1,0.3%(质量分数,下同)交联剂(相对于PVP),2.5%引发剂,60℃反应10 h的条件下,获得的水凝胶在55℃的pH=4.0溶液中可达到的溶胀率超过1700%。温度敏感性实验表明,所制备的CS/PVP凝胶具有很好的温度敏感性,55℃时具有最大溶胀率。pH敏感性实验表明,当pH=4时,溶胀率最大;pH在4～7之间,溶胀率变化较小;7～13之间,溶胀率迅速减小;pH超过13后,变化趋势再次变缓。

Chitosan/polyvinylpyrrolidone（CS/PVP） hydrogels with the properties of thermo-sensibility and pH-sensibility were prepared,using glutaraldehyde as cross-linking agent and ammonium ceric nitrate as initiator.The effects of preparation conditions on swelling ratio of hydrogels were investigated.The results indicate that under the optimal conditions,that is,m（PVP）∶m（CS） =10∶1,2.5% initiator,0.3% cross-linking agent,60 ℃ and 10 h,the swelling ratio of hydrogels is more than 1700% in the solution with pH value of 4.0 under 55 ℃.Thermo-sensitive and pH-sensitive experiments show that the hydrogels are of excellent thermo-sensibility and pH-sensibility.Thermo-sensitive experiments indicate that the maximum equilibrium swelling ratio is obtained at 55 ℃.The pH-sensitive experiments show that the maximum swelling ratio of hydrogels is at pH 4.0.While the pH value is between 4.0 and 7.0,the change of swelling ratio is gently.While the pH value between 7.0 and 13,the ratio decrease obviously and drastically.And while the pH value was above 13,the change of ratio becomes gently again.