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. (authors)