Preparation And Application Of Block Type Polymer Emulsifier

Amphiphilic block copolymer with hydrophilic and hydrophobic segment is considered as polymer, which has same property with low molecular weight surfactant. Using it as an emulsifier, it can not only improve the stability of the emulsion, but also give some special properties of emulsion product. In recent years, living controlled radical polymerization technology(mainly including, NMP polymerization, ATRP polymerization, RAFT polymerization) has became a way to prepare amphiphilic block copolymer. Compared with other polymerization way, RAFT polymerization which has many advandage, such as, a wide range of monomers, mild reaction conditions, simple process, preparation copolymer with different structures(block, comb, star) and no limitation of polymerization processes (such as in bulk, solution, emulsion, super critical CO2), has attracted increasing attention. In this thesis, a series of amphiphilic block copolymers were prepared by RAFT polymerization and used as an emulsifier in emulsion polymerization.Ploy(Steary methacrylate) is synthesized by RAFT polymerization, using S-1-dodecyl-S’-(a,a’-dimethyl-a"-acetie acid) trithiocarbonate(MTTCD) as chain transfer agent, Steary methacrylate as monomer, isopropanol as solvent. The products were characterized by 1H-NMR, FT-IR and GPC. The study of polymerization kinetics shows that the RAFT polymerization of SMA exhibits the first order kinetics, which indicates that the reaction process is living radical polymerization. Ploy(Steary methacrylate)-b-poly(acrylic acid) (PSMA-b-PAA), with different block ratios were synthesized by RAFT polymerization, using Ploy(Steary methacrylate) as chain transfer agent, acrylic acid as monomer. The structure of the product was characterized by FT-IR and 1H-NMR, which indicated that the prepared material was the target product. The molecular weight of the product was tested by GPC. We found that the molecular weight distribution of the product was relatively narrow.The surface activity of PSMA-b-PAA was studied through measuring surface tension, emulsifying properties and foaming properties. The results showed that PSMA-b-PAA had less critical micelle concentration, better emulsifying ability and foam stability.PSMA-b-PAA was used as an emulsifier in butyl acrylate(BA) emulsion polymerization. The effect of reaction conditions and structure of emulsifier on emulsion polymerization were investigated. When n(NaHCO3):n(-COOH)=1.5:1, initiator dosage was 0.8% of monomer and emulsifier dosage was 4% of monomer, emulsion polymerization system was the most stable. The effect of the emulsion polymerization was relatively better while PSMA7-b-PAA37 used as an emulsifier. Latex particles have the morphology of core-shell structure, but the particle size is not uniform.