Completely Amorphous High Thermal Resistant Copolyesters From Bio-Based 2,5-Furandicarboxylic Acid

Polyesters from renewable resources with glass transition temperature (T-g) higher than 100 degrees C are crucial in broadening their application range. In this work, a series of high molecular weight copolyesters, poly(butylene bis[4-(2-hydroxyethoxy) phenyl] sulfone 2,5-furandicarboxylate) (PBSF), was synthesized from bis[4-(2-hydroxyethoxy) phenyl] sulfone (BHEPS), bio-based 1,4-butanediol (BDO), and 2,5-furandicarboxylic acid (FDCA) via transesterification. Nuclear magnetic resonance spectroscopy (H-1-NMR and C-13-NMR) was used to confirm their chemical structures, composition, and sequence distribution. Characterizations demonstrated that with the increasing content of BHEPS unit, T-g of synthesized polyesters was increased from 38.2 degrees C for PBF to 122 degrees C for PBSF-95, in which the content of BHEPS unit was 95%. However, the weight average molecular weight (M-w) of PBSF was dramatically decreased after the addition of BHEPS, from 95,300 g/mol for PBF to only 9600 g/mol for PBSF-95, which was too low for practical application. Taking molecular weight, T-g, and mechanical properties into account, PBSF-65 was considered to be a promising polyester with M-w of 28,500 g/mol, T-g of 104.7 degrees C, tensile strength of 82 MPa, and elongation-at-break of 98%. Besides, it was a completely amorphous polyester with a transmittance of 89.9% by cutoff at 700 nm. Summarily, PBSF-65 showed great potential to be used as raw material for the manufacture of baby bottles, children's toys, kitchen appliances, and beverage packaging, especially in the case when high transparency and heat resistance are required.