RAFT Emulsifier-free Emulsion Polymerization And Self-assembly Of Fluorinated Acrylate Gradient Copolymer

In this thesis, a amphiphilic RAFT agent with six acrylic acid (AA) units was synthesized by the reaction of AA and 2-{[(Dodecylsulfanyl)carbonothioyl]sulfanyl}-propanoic acid. The amphiphilic gradient copolymers of 2,2,2-trifluoroethyl methacrylate (TFEMA) and AA were prepared by emulsifier-free emulsion polymerization technology. Moreover, the self-assembly behavior of the gradient copolymer in selective solvent was studied in detail.The gradient copolymers of TFEMA and AA were successfully synthesized with the amphiphilic RAFT agent via emulsifier-free emulsion polymerization and by working in the starved feed condition of TFEMA. Different cosolvents were added into the polymerization system to inhibit the homopolymerization of AA in aqueous phase. RAFT polymerization kinetics under different reaction conditions were discussed in detail. The optimal polymerization condition in this polymerzaion system was [AA]/TFEMA/[RAFT]/[V501]=133/100/1/0.5 when TFEMA was added drop by drop at a rate of 2.1ml/h at 70℃. The Tg of the copolymer under the optimal polymerization condition was 76.49℃. The gradient structure of the copolymer was characterized by nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC). The latex of the copolymer had good pH stability and Ca2+ stability. The gradient copolymers in selective solvent could form sphere micelles.A series of amphiphilic gradient copolymers were obtained by batch RAFT emulsifier-free emulsion polymerization. The influence factors of the self-assembly such as molecular weight, molar ratios of monomer units and pH values of solution mixtures were studied in detail. The gradient copolymers could form sphere micelles in high water content or in alkaline environment and they would from stick micelles or branched tubular micelles in low water content or acidic environment.In addition, the block copolymer of TFEMA and AA was prepared by using macro-RAFT agent. The conversion and kinetics of polymerization were studied. The block copolymer had two Tg. The ratio of AA block/TFEMA block in the chain was 18:1. The block copolymer [P(AA-b-TFEMA)] in selective solvents also could form sphere micelles. The size of the micelles would become bigger when the water content decreased or self-assembly solution dialyzed.