Atom transfer radical polymerisation - towards the synthesis of a fully-functional photorefractive polymer

Abstract

Atom transfer radical polymerisation (ATRP) of styrene in xylene solution
initiated with 1-phenylethyl bromide and mediated by CuBr/N-propyl-2-
pyridinemethanimine catalyst complex was studied. The polymerisation was ill-controlled, yielding polymers with broad molecular weight distributions and values of number average molecular weight considerably higher than the theoretical values calculated from 100% initiator efficiency. The degree of control afforded over the polymerisation was enhanced by use of a more soluble catalyst complex, CuBr/N-octyl-2-pyridinemethanimine. Furthermore, the use of a more polar solvent, diglyme, generated a homogeneous catalyst complex that facilitated the production of polymers having narrow molecular weight distributions (1.10 < PDi < 1.20).
The kinetics of the atom transfer radical polymerisation of methyl methacrylate
at 90°C in diglyme solution initiated with ethyl-2-bromoisobutyrate and mediated by CuBr/N-octyl-2-pyridinemethanimine was studied and the orders of the reaction were established. The effect on the rate of polymerisation of the ratio of CuBr:N-octyl-2-pyridinemethanimine was also determined.
The temperature dependencies of the rate of polymerisation of methyl
methacrylate in diglyme solution and xylene solution were studied, and were found to be non-linear and dependent upon the polarity of the solvent.
The use of highly polar aprotic solvents, such as N,N-dimethylformamide and
dimethylsulphoxide, was found to be detrimental to the degree of control afforded over the polymerisation of methyl methacrylate. This was circumvented by use of a 5-fold excess, over that conventionally used, of catalyst complex.
The atom transfer radical polymerisation of (4-nitrophenyl)-[3-[N-[2-
(methacryloyloxy)ethyl]carbazolyl]]diazene in dimethyl sulphoxide solution was
studied. Although homopolymerisation yielded only oligomers, copolymerisation of this monomer with methyl methacrylate was found to be readily achievable.
Keywords: ATRP, Styrene; Methyl methacrylate; Polar solvents; Fully-functional
photorefractive polymer.
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Date of Award	Sept 2000
Original language	English
Supervisor	Allan J Amass (Supervisor)