Effect of the side chain structure on the glass transition temperatures of some poly(thiocarbonate)S

A series of poly(thiocarbonate)s with aliphatic, aromatic and cycloaliphatic side groups has been prepared and the glass transition temperatures (T_g)s of these polymers were measured by differential scanning calorimetry (DSC). The magnitude of the T_g was related to the bulkiness, flexibility, and polarity of the pendant groups attached to the polymer main chain. A general decrease in T_g values is observed when these polymers are compared with the corresponding poly(carbonate)s analogues. Theoretical calculation of T_g for some of the polymers were carried out using the method described by Van Krevelen et al. These values are in fair agreement with the experimental values. The critical value of the chain length at which T_g becomes constant (T_g^-8 was calculated for all the polymers using the relation proposed by Cowie. It was found that the molecular weights of the polymers are too low for T_g to become independent of the chain length.