Synthesis of bio-based waterborne polyesters as environmentally benign biodegradable material through regulation of unsaturated acid structure

• Published in: European polymer journal 2021-08, Vol.156, p.110632, Article 110632
• Main Authors: Gao, Chuanhui, Zhang, Jing, Zhang, Di, Dong, Yajie, Wang, Sikai, Peng, Jincheng, Liu, Yuetao
• Format: Article
• Language: English
• Subjects: Biodegradability; Biodegradation; Bonding; Carbon; Chemical reactions; Chemical synthesis; Citric acid; Coatings; Crosslinking; Density; Environmental protection; Food packaging; Glutathione; Glutathione(GSH); Mechanical properties; Polyester resins; Polyesters; Thioether bonds; Unsaturated acid; VOCs; Volatile organic compounds; Waterborne polyesters
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/j.eurpolymj.2021.110632

[Display omitted] •Waterborne polyesters cured films were obtained by thiol-ene click reaction.•The C-S bonds made the curing films have special degradation properties.•The effect of the acid structure on different properties of polyesters was studied. Waterborne unsaturated polyesters has the characteristics of no emission or low volatile organic compounds (VOC), which has been widely used in environmental protection materials such as coatings, food packaging and so on. However, due to the crosslinking network formed by the cured carbon–carbon double bonds (C = C), how to maintain its biodegradability is still a difficult problem. In this paper, three kinds of aliphatic waterborne unsaturated polyesters with different compositions were synthesized from corn, citric acid and apple juice by melt polycondensation. Then, the waterborne unsaturated polyesters were further cured into films by the thiol-ene click reaction. Finally, the results showed the polyesters containing different unsaturated segment showed obvious differences in cross-linked density, mechanical properties and biodegradation rate. It was observed the cross-linking density (18.816 × 10-4 mol/mL) and the degradation rate (25.59 wt%) of the polyesters were the highest when the unsaturated double bonds were in the side chain. And the high degradation rate was attributed to the selective degradation of C-S-C bonds by glutathione and the secondary degradation of ester bonds by lipase. Thus, the combined biodegradable water-based polyesters have a wide application prospect as an environmentally friendly low volatile organic compounds coatings.