Dependence of the glass transition temperature of poly[N-(n-alkyloxy-carbonyl-methyl) Maleimides] and poly[N-(5-n-alkyloxycarbonyl-n-pentyl) Maleimides] on n-alkyl side-chain length

The glass transition temperature has been determined by a refractometric technique for two homologous series of polyN-(n-alkyloxycarbonyl-methyl) maleimides] (PEMIS 1) and polyN-(5-n-alkyloxycarbonyl-n-pentyl) maleimides] (PEMIS 5) with the outer part of the n-alkyl side-chain ranging in length from ethyl to decosyl for PEMIS 1 and from ethyl to decyl for PEMIS 5 and including only the even members of the series. The glass transition temperature is directly related to the number of methylene groups in the outer part of the n-alkyl side-chain (including terminal methyl) of the repeating unit. A semiempirical equation is presented that affords estimates of T_g that are in good agreement with the experimental data.