Preparation Of Polymer Microspheres By Photoinitiated Radical Polymerization

Polymer microsphere is an important material which is widely used in many high-tech industry such as fine electronic manufacturing, information storing, medicine transferring, biological catalysis, etc. Polymerization initiated by heat is a commonly used method to prepare polymer microsphere with unsaturated monomer as raw material. In order to obtain uniform particles with narrow particle size distribution (PSD), rigorous reacting conditions is kept in a relatively long period during polymerization. Among the polymerization methods, UV-curing has been industrialized in many industries including paint, binder, UV-ink. And it interests many researchers because of the advantage of speed, energy saving and environment-friendly.In this work, polymer microspheres were prepared from different kind of monomers by in situ emulsion polymerization initiated by UV and the thermodynamic properties of these microspheres were further examined. The result indicates that styrene is hardly cured by UV as a common polymeric monomer because it serves as a polymerization inhibitor in the polymeric system. The monomer used on UV-curing is mostly acrylic ester with lower glass transition temperature (Tg). Tg of TMCHA is17℃, Tg of CTFA is20℃,and Tg of IBOMA is up to102℃due to its special space steric effect. Tg of polymer blend could be67℃by commixing IBOMA, CTFA and DOGDA as the ratio of5:4.5:0.5.After getting a good knowledge of the thermodynamic property of several main monomers, microspheres with different particle size were obtained by suspension polymerization and the effect of stabilizer and viscosity of aqueous phase to particle size was investigated. The results show that the product D50is62μm under synergistic effect of PVA and HAP, while it will decrease to15μm in the experiment with0.12g Xanthan Gum as thickening agent.To obtain little microsphere, in situ emulsion polymerization was adopted in our experiment. After studying the effect of emulsifier, stabilizer, pigment and monomer to product particle size, we prepared polymer microspheres with particle size around6μm and span2.33, during which IBOMA/CTFA/DOGDA was employed as reactant, MA100carbon black as colorant, OP-10as emulsifier and PVA as protective colloid.The results show that acrylic ester can polymerize through radical polymerization which is initiated by UV. By adjusting the ratio of monomers, polymer blend materials with different Tg is prepared. And polymer microspheres can be obtained through suspension polymerization or in situ emulsion polymerization.