Solvent effect on radical polymerization of butyl acrylate

Abstract

AbstractThe propagation and termination rate constants kp and kt for the radical polymerization of butyl acrylate initiated by biacetyl have been measured by using the rotating‐sector method, in various solvents at 30°C. The value of kp and initiation rate Ri varied with solvents, while the value of kt did not change with solvents except for benzonitrile. The variation of kp with aromatic solvents has a trend against Hammett σp of the solvent substituents similar to that for methyl methacrylate or phenyl methacrylate except for the value in benzonitrile, when it is larger than the variation for methyl methacrylate or phenyl methacrylate. The larger variation of kp for butyl acrylate is compatible with the view that the origin of the solvent effect lies in complex formation between the propagating radical and aromatic solvent molecules. The exceptional decrease in kp and kt in benzonitrile is explained by a contraction of the poly(butyl acrylate) chain in the poor solvent.