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

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。

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

The investigation of the preparation technique of polymeric hollow microsphere is very important for the fuel container of inertial confinement fusion (ICF). The 1% of Tween 20 (T-20) nonionic surfactant is used to modify ozonated polystyrenes microspheres to improve the dispersion of the polystyrene-polyvinylalcohol (PS-PVA) double-layer emulsion microspheres in oil phase and to enhance the survival rate of large size double microspheres. The T-20 treated PS single-layer microspheres are subsequently immersed into PVA solution and encapsulated by PVA. Then the curing technique is used to ensure the fabrication of monodispersed PS-PVA double-layer emulsion microspheres. The results reveal that the contact angle of PS film can be obviously decreased due to the T-20 surface modification of PS. In addition, both the interaction between PS and PVA and the absorption rate of PS film to PVA are greatly enhanced. The infrared spectroscopy and ultraviolet spectroscopy results show that part of absorbed T-20 surfactant on PS surface is replaced by PVA and immigrates into PVA solution in the curing procedure of PVA because of the large dimension of PVA macromolecular. The immigration of T-20 results in the increase of the viscosity ratio of water phase to oil phase and the obviously decrease of the surface tension for PVA during the process of fabricating double-layer emulsion microspheres. The dispersion of PS-PVA double microspheres in oil phase is also improved. The survival rate of large size double-layer hollow microspheres after modified by T-20 remarkably increases to 50%. Therefore, the T-20 is efficient nonionic surfactant in preparing large size PS-PVA double-layer hollow microspheres.