Synthesis of highly carboxylated monodisperse polystyrene microspheres by dispersion polymerization in fluorinated alcohol

摘要

Fluorinated alcohol is demonstrated as a suitable medium for the preparation of monodisperse carboxylfunctionalized microspheres by dispersion polymerization. In the presence of polyvinylpyrrolidone as stabilizer, coagulum-free monodisperse micrometer-sized copolymers containing up to 30 wt% acrylic acid could be produced via one-stage batch dispersion polymerization with 2,2,2-trifluoroethanol as the medium. The coefficient of variation for the particle size distribution decreased as the acrylic acid content in the monomers increased and stabilized at approximately 3% when the acrylic acid content was 15 wt% or higher. The resulting microspheres exhibited pHsensitive behavior. Dissolution of the copolymer chains in alkaline solution could be reduced by incorporating a cross-linkable comonomer. The monodispersity and colloidal stability of the carboxyl-functionalized microspheres were preserved until the amount of divinylbenzene reached 2 wt% based on the monomer. It was found that two-stage semi-continuous dispersion polymerization was an effective method for the synthesis of cross-linked carboxyl-functionalized microspheres.