Application Of RAFT In Soap-free Emulsion Polymerization Of St/IA

Polystyrene has the advantages of light weight,high hardness,excellent impact resistance,water moisture resistance and excellent thermal insulation.However,the application and development of polystyrene produced by traditional emulsion polymerization are limited due to the difficulty of removing emulsifier and the complexity of post-treatment process.Due to the fact that emulsifier is not needed in the emulsifying process,soap-free emulsion polymerization can prepare pure and single dispersed polymer latex particles,which can avoid the influence of emulsifier on the properties of the product,and is favored by many researchers.In this paper,styrene/itaconic acid(St/IA)soap-free emulsion was prepared by reversible addition-break chain transfer polymerization(RAFT)polymerization.The effects of reaction temperature and molar ratio of chain transfer agent and St on particle size,gel rate monomer conversion and other factors were studied.Styrene monomer is used as raw material,and biomass chemical raw material itaconic acid is used as comonomer.Oil-soluble small molecule dibenzyl trithiocarbonate(DBTTC)and water-soluble double carboxymethyl trithiocarbonate(BDMAT)as reversible addition-break chain transfer agent are prepared.It is found that the nucleation mechanism of polystyrene in the soap-free emulsion polymerization is the homogeneous nucleation ratio of St/IA,the molar ratio of chain transfer agent/St and the reaction temperature are the main factors affecting the emulsion properties.In the soap-free emulsion polymerization of RAFT with water-soluble small molecule BDMAT as chain transfer agent,the molar ratio of St/IA was 8:1,the reaction temperature was 78 ? without the addition of emulsifier,the molar ratio of BDMATT / St was 0.032: 1,and the reaction temperature was 78 ?.St/IA emulsionwith 110 nm particle size was obtained by RAFT polymerization.Under this condition,The Zeta potential can reach-65 mV,and the complete reaction rate is faster in 6 hours.The synthesized latex particles are core-shell structure.In the soap-free emulsion polymerization of RAFT with oil soluble small molecule DBTTC as chain transfer agent,under the condition that the ratio of St/IA is10/1,the ratio of DBTTC/St is 0.064:1 and the temperature is 78 ?,the emulsion of98 nm size has been synthesized to further reduce the average emulsion size.The stability of the synthesized emulsion can be kept for 180 days by this method.RAFT soap-free emulsion polymerization with two chain transfer agents was used to synthesize polystyrene emulsion with smaller particle size and narrower particle size distribution.Compared with the traditional soap-free emulsion polymerization method,the emulsion particle size was greatly reduced.