The Preparation And Application Of Iodine Macromolecular Chain Transfer Agent

Core-shell emulsion finds many important applications in industrial fields. The high grafting efficiency enables the according products to exhibit excellent performances. In this thesis, the Iodide-mediated chain transfer agent was used to produce the core-shell emulsion with the high grafting efficiency attributing to the degradation transfer effect. Two series of seeded emulsion were synthesized by the seeded and graft emulsion polymerization of styrene introducing iodoform as chain transfer agent. Accordingly, the diameter of the latex particles in the seeded emulsion was about 150 nm and 30 nm. Graft copolymerization of methactrylate by the intermittent feeding process was successfully carried out to prepare PS-graft-PMA. Polystyrene ion exchange resin with pores was prepared with iodoform as chain transfer agent, and then PS-graft-PMA was obtained via the iodine degradation transfer effect.Core-shell emulsion with high grafting efficiency was prepared by using the iodine degradation transfer effect. First, the cross-linked polystyrene seed latex molecules with iodine atom end groups was obtained by using the iodoform as chain transfer agent for styrene polymerization, and then core-shell emulsion was prepared by adding the second monomer for graft polymerization of methyl acrylate. Iodine atoms in the end of the macromolecular chains can effectively play the role of chain transfer agent, thus, the monomer grafting and grafting efficiency was greatly improved. The results showed that the chain transfer efficiency of the seed emulsion went up with the increase of iodoform.For the synthesis of the styrene copolymer emulsion with small diameter, the catalytic-redox method was used. And it's found that copper sulfate could enhance the redox reaction. The method above could increase the number of latex particles and reduced the size of the latex particles. So it was an effective method for the preparation of small particle size of emulsion. And there were no reports focusing on the catalytic-redox method for the preparation of the small particle size of styrene copolymer. The experimental conditions have been optimized to prepare PS emulsion with the particle size of about 30 nm, and the results had good reproducibility. Comparison the small size of polystyrene latex emulsion with the bigger size of PS particle, the former one had better chain transfer effect.Polystyrene ion exchange resin with pores was prepared via suspension polymerization with iodoform as chain transfer agent, and then tert-butyl acrylate was grafted into PS by using two methods:direct suspension polymerization and solution polymerization. Then the resulted product was hydrolysized by using trifluoroacetic acid, and then PS-g-PAA was obtained. The results proved that polystyrene ion exchange resin with low degree of cross-linking had better chain transfer effect compared with high degree of cross-linking.