Preparation of functional polymer microspheres by suspension copolymerization of diallyl phthalate with carboxylic monomers

Abstract

A study was made of the suspension copolymerization of diallyl phthalate (DAP) and acrylic and methacrylic acid (AAc and MAc, respectively, which were charged after delay to the suspension of partially prepolymerized DAP) and the structure of resulting gel particles. In the copolymerization of DAP with AAc, the conversion of AAc leveled off despite an appreciable amount of AAc remaining in the aqueous phase, whereas in DAP–MAc copolymerization most MAc was polymerized in the particles. The particle structure depended significantly on the mode of comonomer charge. Earlier charge of the comonomer to the reaction system resulted in the formation of particles having comonomer unit-rich surface layer. This was interpreted in terms of phase separation through loosely crosslinked structure in the particles and supported by an adsorption test using a dye and the observation of surface structure of the particles. The timing of comonomer charge changed the amount of comonomer units in the surface layer from 0.06 to 0.60 mmole/g particle.