Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE Near-infrared-responsive PLLA/PLCL/CZP composites integrate PLCL-assisted chain mobility with CZP-enabled photothermal conversion. Under 808 nm irradiation, localized heating activates rapid shape recovery within a mild 50°C–55°C switching window. The system offers remote, light-addressable actuation and programmable 4D-printed scaffolds for potential smart biomedical applications.

ABSTRACT
Conventional poly(l-lactic acid) (PLLA) exhibits a relatively high switching temperature, limiting its on-demand actuation under mild biomedical conditions. Herein, poly(l-lactide-co-ε-caprolactone) (PLCL) was incorporated into PLLA to improve chain mobility and elasticity, and (MWCNTs–ZnO)@polydopamine nanoparticles (CZP) were introduced to construct a near-infrared (NIR)-responsive photothermal shape-memory system. The resulting PLLA/PLCL/CZP composites showed improved crystallinity, mechanical performance, and light-triggered actuation. At 1 wt% CZP, the film exhibited optimal tensile properties, with a tensile strength of 24.5 MPa and an elongation at break of 373%. Under 808 nm NIR irradiation, the composites rapidly recovered their original shape at approximately 55°C, enabling remote and mild-temperature actuation. Direct-ink-written 4D-printed scaffolds displayed high print fidelity and enhanced compressive properties, with 3 wt% CZP reaching a compressive strength of 5.2 MPa and a modulus of 0.6 MPa at 40% strain. The scaffolds showed shape-fixity ratios above 95% and recovery ratios above 80%. Biological evaluations revealed acceptable initial cell adhesion, concentration-dependent cytocompatibility, and antibacterial activity against E. coli and S. aureus. This work provides a tunable platform for NIR-triggered shape-memory actuation and programmable 4D-printed biomedical scaffolds.