Effect of Chain Stereoconfiguration on Poly(3-hydroxybutyrate) Crystallization Kinetics

• Published in: Biomacromolecules 2022-09, Vol.23 (9), p.3847-3859
• Main Authors: Caputo, Maria Rosaria, Tang, Xiaoyan, Westlie, Andrea H., Sardon, Haritz, Chen, Eugene Y.-X., Müller, Alejandro J.
• Format: Article
• Language: English
• Subjects: 3-Hydroxybutyric Acid; Crystallization; Hydroxybutyrates - chemistry; Kinetics; Polyesters - chemistry
• ISSN: 1525-7797; 1526-4602; 1526-4602
• DOI: 10.1021/acs.biomac.2c00682

Poly­(3-hydroxybutyrate) (PHB) is naturally accumulated by bacteria but can also be synthesized chemically. Its processability is limited, as it tends to degrade at temperatures above its melting temperature; hence, investigation into crystallization kinetics and morphology of PHB materials of both natural and synthetic origins is of great need and interest to get a better understanding of structure–property relationship. Accordingly, this contribution reports a first study of the crystallization and morphology of synthetic PHB materials of different molecular weights. These synthetic PHBs are racemic mixtures (50/50 mol %) of R and S chain configurations and are compared with an enantiopure bacterial R-PHB. Nonisothermal and isothermal crystallization studies show that R and S chains of PHB can cocrystallize in the same unit cell as the R-PHB. Most significantly, the results show that the presence of S chains decreases the overall crystallization rate, which could enhance the processability and industrialization of PHB-based materials.