Precise Synthesis of a Series of Poly(4-n-Alkylstyrene)s and Their Glass Transition Temperatures

Poly(4-n-alkylstyrene)s with six kinds of n-alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and octyl groups covering wide molecular weight range from around 5 k to over 100 k were precisely synthesized by living anionic polymerizations. It was confirmed that all the polymers obtained have narrow molecular weight distribution, that is, Mw/Mn is all less than 1.1, by SEC. Tgs of all the polymers were estimated by DSC measurements and it turned out to be clear that their molecular weight dependence was well described by the Fox-Flory equations. Furthermore, it is evident that Tg monotonically decreases as a number of carbon atoms of n-alkyl group is increased, though Tg values are all 20 K or more higher than those reported previously for the same polymer series. This is because backbone mobility increases by introducing longer n-alkyl side groups with high mobility, while Tg difference in between this work and the previous one may due to the experimental conditions and also to the molecular weight range adopted. (C) 2017 Wiley Periodicals, Inc.