THE POLYDISPERSITIES OF POLYMERS RECOVERED BY PRECIPITATION IN NON-SOLVENTS - EFFECTS OF BETA-METHYLSTYRENE ON THE POLYMERIZATION OF METHYL-METHACRYLATE

Recovery of a polymer by precipitation in a non-solvent may lead to lo ss of some of the smaller polymer molecules so that the value of <(DP) over bar>(w)/<(DP)over bar>(n) for the recovered material is less than that for the whole polymer. The point is illustrated for poly(methyl methacrylate) precipitated in hexane and in methanol; the hydrocarbon is the more effective precipitant and leads to materials having higher values of <(DP)over bar>(w)/<(DP)over bar>(n) than those found for po lymers recovered from methanol. Further evidence is presented to show that beta-methylstyrene has a very significant effect upon the termina tion process during the radical polymerization of methyl methacrylate. (C) 1998 Elsevier Science Ltd. All rights reserved.