The catalytic chain transfer emulsion polymerisation of acrylic monomers
Morsley, David Robert
mesheuropmc: eye diseases | genetic structures
This thesis has explored the synthesis of macromonomers by Catalytic Chain\ud Transfer (CCT) emulsion polymerisation.\ud It has been shown that the effective synthesis of methacrylate macromonomers\ud using catalyst concentrations below a threshold level is not possible since the\ud viscosity in the particles becomes too high to allow efficient movement of the\ud CCT agent between latex particles. It has been demonstrated that an addition of\ud a shot of monomer at the start of the reaction is necessary to allow effective CCT\ud to occur.\ud The addition of the water soluble methacrylate monomer HEMA to a methyl\ud methacrylate CCT emulsion polymerisation was shown to have little effect on\ud the transfer reaction. Macromonomers consisting of a statistical mixture of\ud MMA and HEMA can therefore be easily prepared by CCT emulsion\ud polymerisation.\ud The results of CCT emulsion polymerisation where the synthesis of butyl\ud acrylate/ methyl methacrylate macromonomers were attempted were also\ud outlined and effective macromonomer synthesis was observed for low amounts\ud of acrylate. For higher amounts of acrylate it was observed that effective\ud macromonomer synthesis was only observed up to moderate conversions.\ud The synthesis of methacrylic acid containing macromonomers using CCT\ud emulsion polymerisation was studied and it was shown that controlled\ud macromonomer synthesis could only be carried out at low methacrylic acid\ud concentrations.\ud Results described show that the effectiveness of the CCT emulsion\ud polymerisation process is very dependant on the solublity of the catalyst. The\ud more the CCT agent is soluble in the monomer and hence particle phase the\ud greater the observed transfer constant. If the catalyst is too soluble in the\ud monomer the observed transfer constant is greatly reduced due to the inability of\ud the catalyst to transport from the monomer droplets to the particles effeciently.
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