Thermally Activated Shape-Memory Behavior of SLA-Printed PDMS-PCLDMA Hybrid Networks

Vat photopolymerization offers a powerful route for high-resolution 4D printing; however, designing shape memory polymers that simultaneously exhibit printability, mechanical robustness, dimensional fidelity, and efficient thermally triggered shape memory behavior remains challenging. In this study, an SLA-printable silicone-semicrystalline hybrid photoresin based on polydimethylsiloxane (PDMS-MMA), polycaprolactone dimethacrylate (PCLDMA), triethylene glycol dimethacrylate (TEGDMA), and trimethylolpropane trimethacrylate (TMPTMA) was developed. The effects of PDMS-MMA and TMPTMA contents on network structure, dimensional stability, mechanical properties, and shape-memory behavior were investigated. Increasing PDMS-MMA content reduced linear shrinkage from 2.1% to 1.7%, suggesting improved dimensional stability associated with increased network flexibility, whereas increasing TMPTMA content enhanced network compactness and reduced swelling. P20T5 exhibited a shape fixity of 95.96% and a recovery ratio of 99.07% in the second cycle. These results demonstrate that balancing flexible silicone segments, semicrystalline switching domains, and covalent network constraints enables the fabrication of SLA-printable hybrid networks with thermally responsive shape-memory behavior.