Regulating the Characteristic Networks of Biodegradable Poly(l‑malic acid-ε-caprolactone) Shape-Memory Materials: From Plastics to Elastomers

Developing new biodegradable polyesters with well-defined structures is of interest. We reported an attractive two-component aliphatic polyester-based thermoset, which was prepared via the esterification of biomass-derived l-malic acid oligomers and three-arm poly(ε-caprolactone) (3a-PCL) triols. The chemical network formed via the ester bonding and physical network caused by the crystallization of a 3a-PCL arm chain coexist in the thermoset, and the competition of the two characteristic networks leads to a negative correlation between the degree of covalent cross-linking and the degree of crystallization; thereby, the mechanical state of the thermosets can be easily tuned: from the plastic to elastomer state. Moreover, the crystallization temperature and melting point of the thermosets range in 30 °C ∼ 50 °C and −7 °C ∼ 18 °C, respectively, which are favorable for shape morphing as the thermosets are used as shape-memory materials. This work also provides valuable information about tailoring the mechanical and thermal properties of star-shaped polyester-based thermosets.