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The design and preparation of hollow nonspherical microparticles are of great significance for their potential applications, but the development of a facile synthetic method using only one production step remains a great challenge. In the current work, a new template-free method based on dispersion polymerization was successfully developed to produce anisotropic hollow polystyrene (PS) microparticles in a single step. In the synthesis, ammonium persulfate (APS) played a critical role in the formation and growth of highly uniform and stable hollow PS microparticles. By varying the concentration of APS and that of the stabilizer used, polyvinylpyrrolidone, we were able to control the average size of the PS particles and their degree of concavity. Based on our results and observations, a plausible mechanism for formation of these unusually shaped PS microparticles was proposed.

Exclusive formation of poly(ethylene-co-styrene)s were observed by introduction of ethylene into the solution of syndiospecific styrene polymerisation using Cp'TiCl(2)(O-2,6-(i)Pr(2)C(6)H(3)) (Cp' = 1,2,4-Me(3)C(5)H(2), tert-BuC(5)H(4))-MAO catalysts without by-production of syndiotactic polystyrene, whereas the styrene polymerisation did not proceed when ethylene was removed from the reaction mixture of ethylene/styrene copolymerisation.

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