Radical copolymerization of 2,4-disubstituted enynes with electron-accepting comonomers

The radical copolymerization of 2,4-disubstituted enynes (CH2=C(CH3)-CdropC-R: R = Ph (1a), n-Bu (1b), t-Bu (1c), and (CH3)(3)Si (1d)) with various electron-accepting comonomers is described. The copolymerization gave corresponding copolymers whose yields were dependent upon the electronic character of the comonomers. The enyne components in the copolymers from 1a and 1d consisted of the specific 1,2-polymerized units, while those from 1b and 1c consisted of both the 1,2- and the 1,4-polymerized units. The copolymerization of 1b (R = n-Bu) showed a significant change in the ratio of the 1,2- and the 1,4-polymerized units by the electronic character of the comonomers. Namely, the copolymers with a higher content of the 1,4-polymerized units were obtained by the copolymerization with comonomers having higher electron-accepting ability.