Bio-based PBS copolyesters derived from a bicyclic d-glucitol

Abstract

2,4:3,5-di-O-methylene-D-glucitol (Glux-diol) was used for the synthesis of poly(butylene succinate) (PBS) copolyesters by melt polycondensation. Glux-diol possess a rigid bicyclic asymmetric structure made of two fused 1,3-dioxane rings and two hydroxyl functions at the end positions. Copolyesters were prepared over the whole range of compositions with molecular weights varying from 26 000 to 46 000 g mol⁻¹ and a random microstructure. The thermal stability of PBS did not significantly alter with the presence of Glux units. The glass transition temperatures (T_g) steadily increased from −28 to 80 °C along the whole copolyester series with the insertion of Glux. On the contrary, melting temperature (T_m) and crystallinity decreased because of the lack of regularity of the polymer chain although copolyesters with contents of Glux units up to 30 mole% were semicrystalline. The stress–strain behavior changed according to variations produced in thermal transitions. The replacement of 1,4-butanediol by Glux-diol slightly increased both the hydrolytic degradability and the biodegradability of PBS. Compared to other bicyclic sugar-based diols reported in the literature, Glux-diol appeared to be more efficient in both increasing the T_g and enhancing the susceptibility to hydrolysis of PBS.