快速响应的温敏性聚(N-异丙基丙烯酰胺)水凝胶 Ⅰ.以CaCO_3为成孔剂制备方法、表征及动力学研究

以不同粒径的CaCO3粒子为成孔剂 ,合成了快速响应的温敏性聚 (N 异丙基丙烯酰胺 ) (PNIPA)水凝胶 .利用扫描电镜观察到水凝胶具有特殊的孔状结构 ,得到水凝胶的孔径大小为几十微米左右 .动力学研究表明 ,该水凝胶在温敏膨胀或收缩时 ,具有快速的响应速率 ,在 10min内的失水率可达 90 % .比较了干凝胶和4 0℃下失水后的凝胶两种不同状态下水凝胶的膨胀曲线 ,发现两者的溶胀动力学曲线明显不同 ,前者的曲线有拐点 .同时发现与失水收缩速率相比 ,水凝胶具有较慢的吸水膨胀速率 .

FAST RESPONSIVE THERMOSENSITIVE POLY(N-ISOPROPYLACRYLAMIDE) HYDROGELS Ⅰ. SYNTHESIS,CHARACTERIZATION AND KINETIC BEHAVIOR

Fast responsive thermosensitive PNIPA hydrogels were synthesized by using different meshes of CaCO 3 particles as pore foaming agent. From the observation by a scanning electron microscope, it was found that these gels consisted of a porous structure. The gels possess pores in the size range 10～100 μm. Such porous hydrogels swelled or shrank much faster in response to the change of temperature than conventional hydrogels. More than 90% of water could be expelled from the porous hydrogels within 10 min when the temperature of the hydrogels was raised to 40℃. The reswelling curve of the xeogel was compared with the reswelling curve of the hydrogel shrunk to equilibrium state at 40℃, which showed a significant difference and an inflexion was found in the former. In comparing with the shrinking rate, the swelling rate of the porous hydrogels is relatively slower.