The Preparation And Properties Of High Cross-linking Hollow Polymer Particles With Large Size

Hollow polymer latex particles have attracted much attentionbecause of its wide range of applications in paints, pharmaceuticals,aerospace and other fields. The emulsion polymerization is one of theearlier proposed methods to synthesize hollow microspheres, and therehave been new processes which have been proposed to. This paper wasaimed to prepare polymer hollow microspheres through phase separationand multi-step seeded emulsion polymerization.1When we prepare hollow particles by phase separation, the seedlatex particles and hollow particles prepared by conventional emulsionpolymerization process and miniemulsion process were significantlydifferent. While comparing the performance of seed particles prepared byhigh pressure homogenization and ultrasound process, the morphology ofthe seeds and hollow microspheres were characterized by electronmicroscopy. This paper discussed the influence of different amount of theemulsifier and co-emulsifier on the performance of seeds and hollowspheres, and the best process was determined eventually. 2Multi-step seeded emulsion polymerization is a new processproposes to prepare hollow microsphere with large diameter. Firstly,nanoscale seed latex particles were synthesized through pre-emulsionpolymerization, the core monomer polymerized on seed particles earlier,the shell monomer coated later. The latex particles prepared by previousstage were the seeds of next stage. Monodisperse particles were preparedby “hunger feeding” process. Then, the core-shell latex particles weregradually treated by alkali/acid in high temperature to form hollowstructure. Finally, in the system blended with emulsifier and dispersant,monomer and crosslinking agent polymerized on the surface of hollowparticles and formed cross-linked shell. This paper discussed theinfluence of different amount of the crosslinking agent, core-shell ratio,heat treatment temperature and other conditions on the performance ofseeds and hollow spheres, and determined the appropriate formula andprocess conditions. The morphologies of particles in each stage werecharacterized by transmission electron microscopy (TEM), as well as theaverage diameters and distributions of latex particles in thepolymerization process of each stage were characterized by dynamic laserscattering (DLS).