Preparation Of PAS Amphiphilic Block Polymer By RAFT Polymerization And Its Application In Emulsion Polymerization

In this paper,the small molecule raft reagent 2-tert-butylthiol carbonyl acyl acetic acid(BCSPA)was prepared according to the literature.PAA-BCSPA with different structure and composition was constructed by solution polymerization with acrylic acid by reversible addition fragmentation chain transfer polymerization(RAFT).The results show that when n(AIBN): n(BCSPA)= 8:1,reaction temperature is 70 ?,the polymer formation rate is constant,showing obvious characteristics of active polymerization.PAS block copolymers with different compositions and structures were prepared by using macromolecular chain transfer agent.The effects of AIBN and hydrophobic monomers on the polymerization were investigated under the same content of PAA-BCSPA.Based on this,PAS block copolymers' molecular weight are between 2733-2807g/mol and the molecular weight distribution of PAS block copolymers' are between 1.01-1.10,which can regulate the structure of PAS.The effect of sodium bicarbonate alkalization on the CMC value of PAS with the ratio of AA to St was studied.The results showed that the CMC value of PAS decreased with the increase of acrylic acid content in PASN,and the lowest CMC value is 3.97x10-6mol/mlThe polymer PASN was applied to PMMA emulsion polymerization.The results of kinetic tests show that the synthesized macromolecular emulsifier has a regulatory effect on the polymerization rate of emulsion polymerization,and the conversion rate showed a linear relationship with time,and still had reactivity.The structure of emulsion polymerization products was characterized by infrared spectroscopy,and the anchoring effect between macromolecular emulsifier and latex particles was confirmed.The effects of different hydrophobic and hydrophilic ratios on the stability,conversion rate and particle size of the emulsion were studied,and the effects of increasing the solid content of the emulsion on the stability of the emulsion were also studied.The experimental results show that with the increase of solid content in PMMA emulsion system,the size of latex particles increases gradually,and the Zeta potential and conductivity decrease accordingly.As the length of hydrophilic chain in the macromolecular emulsifier PASN increases,the particle size obtained decreases accordingly.Later adding pre-emulsion can effectively increase the solid content of the emulsion,and the emulsion system remains stable.The emulsions synthesized from macromolecular emulsifiers have p H response.The results show that the emulsion system remains stable after adjusting p H value,and the particle size of the emulsion has little change.The effects of different emulsifiers on the molecular weight of latex particles were studied.The experimental structure proves that the self-made macromolecular emulsifier PASN has an effective control on the molecular weight of the latex particles,and the molecular weight distribution is between 1.40-1.64,still in line with the characteristics of active radicals.