Free-radical copolymerization of methyl methacrylate with styrene in the presence of 2-mercaptoethanol

The free-radical copolymerization of methyl methacrylate (MMA) with styrene (St) in the presence of 2-mercaptoethanol (ME) was investigated in order to obtain omega-hydroxy oligomers with tandem copolymer-type main chains and which may be further used to prepare macromonomers. Weak retardation was noticed during polymerization. It was demonstrated that the pseudo-kinetic rate constant method can be successfully applied to this copolymerization, irrespective of the initial monomer ratio. On this basis, the apparent transfer constant of ME was determined under azeotropic copolymerization conditions, and it was found to be intermediate between the corresponding values for MMA and St homopolymerizations. (M) over bar(n) and (M) over bar(w)/(M) over bar(n) of the oligomers prepared increased with conversion. As the copolymerization proceeded, MWD turned from monomodal to slightly bimodal at a conversion depending on the ME/monomer ratio. The functionalities of the oligomers prepared were around unity, making them suitable for macromonomer synthesis. (C) 1998 Elsevier Science Ltd. All rights reserved.