Studies in cyclocopolymerization. V. Further evidence for charge‐transfer complexes in cyclocopolymerization

Abstract

AbstractPrevious work from this laboratory has shown that certain 1,4‐dienes which readily undergo cyclocopolymerization with certain alkenes also form charge‐transfer complexes with the same alkenes. The results observed and the proposed cyclocopolymerization mechanism are consistent with participation of the charge‐transfer complex as a distinct species in the copolymerization. It was the purpose of this investigation to determine whether there was a dilution effect on the relative reactivities of the monomers in support of the charge‐transfer participation concept, and whether the results of a suitable terpolymerization study would also support this postulate. In the divinyl ether–fumaronitrile system, the maximum rate of copolymerization occurred at a monomer feed ratio of 1:2 and the composition of the copolymer was also 1:2 at a total monomer concentration of 3 mole/l. However, when the concentration was progressively lowered to 0.5 mole/l. at the same monomer feed ratio, the fumaronitrile content of the copolymer decreased in a linear manner. In a series of terpolymerization experiments with the divinyl ether–maleic anhydride–acrylonitrile system, it was shown that the divinyl ether–maleic anhydride ratio in the terpolymer was always less than 1:1 and had an upper limit of 1:2, regardless of the feed ratio of the termonomers. These results are consistent with the participation of the charge‐transfer complex of divinyl ether and maleic anhydride in a copolymerization process with either maleic anhydride or acrylonitrile as the comonomer.