Study On Synthesis Of Latex With Functional Amino-containing Monomer

Dimethylaminoethyl methacrylate(DMAEMA) was used to obtain latex having acid-soluble property which can be used as gastric-soluble coatings. The terpolymer latex of Styrene-Butyl acrylate-Dimethylaminoethyl methacrylate was prepared in both batch and semi-batch emulsion copolymerizations. The emulsion copolymerization containing DMAEMA became complex. The effects of emulsifier type and amount, initiator amount, copolymerization temperature, content of DMAEMA, the feed policy and feed rate of comonomers on the stability and conversion of copolymerization system were studied systematically. The results show that increase of content of functional monomer DMAEMA can decrease stability and conversion of copolymerization system. A reduction of the feed rate of monomers is favorable to the process. The results also show that, for this system, batch copolymerization is inferior to semi-batch copolymerization, the nonseeded emulsion copolymerization is inferior to seeded process. The optimizational process is seeded copolymerization using a small amount of Acrylic acid (AA) in nucleation period. The growth of particles was studied primarily in the seeded copolymerization, the results show that increase of the feed rate of monomers and increase of content of DMAEMA can promote coagulation, obtaining large particles.Factors that influencing the acid-solubility of the film were also studied. An increase of DMAEMA content and decrease of the molecular weight of copolymers will favor the solution process.