Effect of cyclobutane carbonitrile rings on the glass transition temperature of vinyl copolymers

A wide compositional range of copolymers of 1-cyclobutene carbonitrile (CBCN) and 1-bicyclobutance carbonitrile (BBCN) with common vinyl monomers was prepared in order to study systematically the effect of cyclobutane carbonitrile ring incorporation on the glass transition temperature (T_g). In general, the T_g's of the copolymers are increased in proportion to the weight percent of the small-ring monomer incorporated, but the 1,2-mode of incorporation raises T_g more than the 1,3-mode. Attempts were made to correlate data with quantitative T_g–composition relationships (Fox–Johnston equations). Prediction for nitrile homopolymer T_g's are compared with literature values.