非离子型表面活性剂Tween 20对大尺寸双层空心微球制备的影响

Effect of Tween 20 nonionic surfactant on preparation of large size double-layer hollow microspheres

为了改善臭氧处理聚苯乙烯(PS)单层球与聚乙烯醇(PVA)溶液生成的双层乳粒在油相中的分散性,提高大尺寸双层球的成活率,在双层球制备过程中采用了非离子型表面活性剂Tween 20(T-20)来改性该种PS单层球。结果表明经表面活性剂T-20改性后显著降低了PS薄膜的亲水接触角,提高了PS与PVA间的相互作用,同时也大幅度提高了PS薄膜对PVA的吸附速率。红外光谱和紫外-可见分光光度计的测试结果证明:在PVA固化过程中,由于PVA与T-20的相比太大,PS表面吸附的表面活性剂T-20部分会被PVA置换、迁移至PVA溶液中。T-20的迁移提高了制备双层球过程中水相与外油相的粘度比且显著降低PVA溶液表面张力,从而有利于实现双重乳粒在油相中的单分散。因此,T-20是制备大尺寸PS-PVA双层空心微球有效的表面活性剂。

The investigation of the preparation technique of polymeric hollow microsphere is very important for the fuel con-tainer of inertial confinement fusion （ICF）. The 1% of Tween 20 （T-20） nonionic surfactant is used to modify ozonated polysty-renes microspheres to improve the dispersion of the polystyrene-polyvinylalcohol （PS-PVA） double-layer emulsion microspheresin oil phase and to enhance the survival rate of large size double microspheres. The T-20 treated PS single-layer microspheres aresubsecuently immersed into PVA solution and encapsulated by PVA. Then the curing technique is used to ensure the fabricationof monodispersed PS-PVA double-layer emulsion microspheres. The results reveal that the contact aflgle of PS film can be obvi-ously decreased due to the T-20 surface modification of PS. In addition, both the interaction between PS and PVA and the absorp-tion rate of PS film to PVA are greatly enhanced. The infrared spectroscopy and ultraviolet spectroscopy results show that part ofabsorbed T-20 surfactant on PS surface is replaced by PVA and immigrates into PVA solution in the curing procedure of PVA be-cause of the large dimension of PVA macromolecular. The immigration of T-20 results in the increase of the viscosity ratio of wa-ter phase to oil phase and the obviously decrease of the surface tension for PVA during the process of fabricating double-layer e-mulsion microspheres. The dispersion of PS-PVA double microspheres in oil phase is also improved. The survival rate of largesize double-layer hollow microspheres after modified by T-20 remarkably increases to 50%. Therefore, the T-20 is efficientnonionic surfactant in preparing large size PS-PVA double-layer hollow microspheres.