搅拌法制备聚合物微球中油水相对壁厚的影响

Effect of oil phase and water phase on wall thickness of polymer microspheres prepared by agitation method

为了研究乳液微封装技术中油水相对微球壁厚的影响,推导了在理想状态下微球壁厚、油相质量分数和油水相比这三者之间的函数关系。结果表明:当内相水滴半径和油相质量分数为常数时,微球壁厚是油水相比的单增函数;而当内相水滴半径和油水相比为常数时,微球壁厚是油相质量分数的单增函数。即提高油相质量分数或增大油水相比对增加壁厚而言具有等效性。根据此规律,在搅拌法制备小直径聚苯乙烯微球中,通过调整油水相的各参数,确定了制备小直径厚壁聚苯乙烯微球的关键工艺参数。实验表明:采用搅拌法制备10～25μm壁厚的小直径聚苯乙烯微球时,油相质量分数宜配制为5.3%～7.0%,油水相比宜控制在1.6～2.2之间,而外水相中聚乙烯醇质量分数宜控制在1%～3%之内。

To study the effect of oil phase and water phase on the wall thickness in the emulsion encapsulation method, an expression of the wall thickness varying with the polymer mass fraction in oil phase and the volume ratio of polymer solution and inner water has been deduced in the ideal state. It is shown that the wall thickness increases with increasing the polymer mass fraction or the volume ratio of polymer solution and inner water. Therefore, the wall thickness can be controlled by adjusting either the polymer mass fraction or the volume ratio of polymer solution and inner water. According to the rule, the optimal parameter values are obtained by varying the parameters of oil phase and water phase in the agitation method for preparing hollow polystyrene （PS） microspheres. The experimental results show that, in order to prepare PS microspheres with 10 μm to 25 μm wall thickness, the PS mass fraction should be controlled in the range of 5.3% to 7.0% while the volume ratio of PS solution and inner water should be within the range of 1.6 to 2.2. Moreover, the optimal range of PVA mass fraction in outer water is between 1% and 3%.