Toughened polylactide-based shape memory materials fabricated via reactive blending

To enhance the compatibility between polylactide (PLA) and poly(ε-caprolactone) (PCL), the two polymers were reactively blended in the presence of hexamethylene diisocyanate (HDI) and a tertiary amine-containing polyol, bis(2-hydroxyethyl) amino-tris(hydroxymethyl)methane (BTM). The reactive blending led to the formation of chain-extended PLA and PCL, as well as PLA-co-PCL copolymers. Additionally, BTM reacted with carboxyl and hydroxyl groups, promoting the formation of a crosslinked network. Gel content analysis revealed an increase with higher BTM loading, indicating a greater extent of internal crosslinking. The PCL phase was dispersed within the PLA matrix in a sea-island morphology. Although the crystallization rate and overall crystallinity of the blends decreased, their mechanical properties were significantly enhanced. Notably, the LHC-3B blend maintained a tensile strength of approximately 40 MPa and exhibited an impressive elongation at break of 441 %. The impact strength of the reactive blends also surpassed that of conventional PLA/PCL systems. At a BTM content of 2.0 wt%, the blend achieved the highest shape recovery rate of 85.4 %, demonstrating excellent shape memory behavior. These results suggest a promising strategy for developing high-performance PLA-based materials with improved toughness and functionality.