P(HEMA-co-MAA)纳米凝胶的制备与pH响应性

以甲基丙烯酸羟乙酯(HEMA)和甲基丙烯酸(MAA)为聚合单体,异辛烷为分散介质,Span80和Tween80为复配乳化剂,采用反相微乳液聚合法制得不同单体配比的聚(甲基丙烯酸羟乙酯-co-甲基丙烯酸)(P(HEMA-co-MAA))纳米凝胶。确定了产物的pKa值及实际单体物质的量比,对产物的形貌进行了表征并研究了产物的pH响应性.结果显示,MAA物质的量分数为20%的纳米凝胶的pKa值为5.83,在pH=3和pH=7时其数均粒径分别为48 nm和90 nm;当环境pH接近pKa值时,纳米凝胶分散液的浊度明显降低,溶胀率明显上升,表观黏度急剧增加,说明纳米凝胶具有良好的pH响应性。

Preparation and pH Responsive Property of Poly(HEMA-co-MAA) Nanogels

A series of poly(methacrylic acid-co-(2-hydroxyethyl methacrylate)) nanogels with the different mole percentages of monomers have been prepared by the inverse microemulsion polymerization.The actual mole percentages of monomers and pKa value of nanogels were determined.The morphology of nanogels have been characterized by transmission electron microscopy(TEM).The pH responsive property of nanogel was researched.pKa of the nanogels with 20% mole percentage of MAA is 5.83,the number-average diameters of the nanogels are 48 nm and 90 nm as the pH=3 and pH=7 respectively.When pH approaches pKa of the nanogels,the turbidity of nanogel dispersion decreases significantly with the swelling rate of nanogels rising obviously and the apparent viscosity of nanogel dispersion increasing sharply,which indicate that the nanogels have an excellent pH responsibility.