Abstract

AbstractPolymerizations of several vinyl monomers at 25°C in aprotic solvents (dimethyl sulfoxide, N,N‐dimethylacetamide, and hexamethylphosphoric triamide) using sodium hydride dispersion as initiator yield low to intermediate molecular weight polymers. The molecular weight of the resulting polymer as well as the mode of initiation depends on the monomer and aprotic solvent used. Initiation of polymerization of monomers with available α hydrogens (methyl acrylate, acrylonitrile) involves monomer anion, while initiation of a monomer with no α hydrogen (methyl methacrylate) proceeds by a more complex mechanism. In contrast, initiation of styrene and α‐methylstyrene proceeds by dimsyl anion addition to monomer in dimethylsulfoxide. Although the triad tacticities and number‐average molecular weights of poly(methyl methacrylate) samples obtained from all three aprotic solvents are nearly the same, poly(methyl methacrylates) prepared in dimethyl sulfoxide and N,N‐dimethylacetamide give polymers having polydispersities of ∼3, while a very polydisperse polymer is obtained in hexamethylphosphoric triamide.

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