Polyterephthalates of 2,3‐disubstituted butanediols‐1,4: Effect of aliphatic substituents on Tg and Tm of the polyesters

Abstract

AbstractPoly(2,3‐dialkylbutanediol‐1,4 terephthalates) with the alkyl substituents CH3, C2H5, n‐C3H7, iso‐C3H7, n‐C4H9, and n‐C10H21, andn‐C16H33 were synthesized from the corresponding 2,3‐dialkylbutanediols‐1,4 and dimethyl terephthalate or terephthaloyl chloride. The substituents of the butanediol‐1,4 portion of the polyterephthalates influence the 13C NMR chemical shifts of the carbon atoms near the branching site, the glass transition (Tg), and the crystallizability. Small alkyl substituents do not change the Tg of the polymers, whereas bulky substituents such as the isopropyl group increase the Tg and long normal alkyl groups as substituents decrease the Tg of the polymers. Crystallinity in these polyterephthalates was found only with CH3 and C16H33 as the 2,3‐dialkyl substituents in the butanediol‐1,4 portion of the polyester. This crystallinity of polyterephthalate of 2,3‐di‐C16H33 substituted butanediol‐1,4 could be assigned to side‐chain crystallization of the paraffinic groups.