INFLUENCE OF POOR SOLVENTS ON RADICAL COPOLYMERIZATION OF STYRENE AND METHYL-METHACRYLATE

Radical copolymerizations of styrene and methyl methacrylate (MMA) were carried out in the presence of poor solvents (50 vol%) at 60-degrees-C. When copolymerizations were carried out in methanol, turbidity was found at 20 mol% of feed MMA, and at 30 mol% or above gelatinous copolymer precipited without turbidity. However, rate of copolymerization (R(ep), copolymer composition, monomer reactivity ratios(tau-b tau-2), and degree of polymerization (P(n) in methanol were similar to those in good solvents. When copolymerizations were carried out in hexane turbidity and precipitate were found at 40 mol% of feed MMA or above, but no turbidity was found at 20 mol%. Although the values of R(ep) between 20 approximately 80 mol% of feed MMA in hexane were smaller than those in methanol, copolymer composition and P(n) except respective values at 80 mol% were similar to those in good solvents. The values of tau-1 and tau-2 determined by neglecting the value at 80 mol% of feed MMA were also similar to those in good solvents. It is considered that the propagating radical at 80 mol% of feed MMA in hexane precipitated by itself and the radical was trapped to increase the MMA composition of copolymer.