Morphology and blowing agent encapsulation efficiency of vinylidene chloride copolymer microspheres synthesized by suspension polymerization in the presence of a blowing agent

ABSTRACT Polymer microspheres were synthesized by the suspension copolymerization of vinylidene chloride (VDC), acrylonitrile (AN), and/or methyl methacrylate (MMA) in the presence of a paraffin blowing agent. The effects of the monomer composition, crosslinking agent content, blowing agent type, and content on the morphology and blowing agent encapsulation efficiency of the microspheres were investigated. The porous and non‐core–shell structure microspheres with a low encapsulation efficiency of blowing agent were formed when VDC was copolymerized with individual AN or MMA, whereas microspheres with a good core–shell structure and a high encapsulation efficiency of blowing agent were formed when the feeding monomer mass ratios of VDC–AN–MMA were 50/20/30, 60/20/20, and 70/20/10. The addition of 0.2–0.4 wt % divinyl benzene crosslinking agent (on the basis of monomer mass) was favorable to the formation of core–shell structure microspheres with a high encapsulation efficiency of blowing agent. Microspheres with wrinkled surfaces and a pronounced internal topography were formed as the carbon atom number of paraffin increased from 5 to 7. The encapsulation efficiency of blowing agent increased as the carbon atom number and content of paraffin blowing agent increased. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44376.