Olfactory-Interactive 4D materials from a carvone-based photocurable resin

The development of 4D materials has expanded adaptive manufacturing; however, most systems are limited to passive shape changes and lack interactive sensory functions. Here, we present an olfactory-responsive 4D material with integrated antimicrobial activity. The material exhibits shape-memory behaviour under external stimuli and releases aromatic compounds upon heating, enabling multisensory interaction. A photocurable resin was formulated using carvone, a naturally derived monoterpene from spearmint, as a nonreactive diluent, together with diurethane dimethacrylate (DUDMA) and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO). Containing up to 25% renewable content, the formulation provides a sustainable alternative to conventional petroleum-based systems. The resulting 4D-printed materials demonstrate stable mechanical and shape-memory performance, a transition temperature of 80 °C, and effective antimicrobial activity against E. coli and S. aureus. Polymerisation kinetics in the presence of carvone were evaluated using HEMA and MMA as model monomers. HEMA reached 73% conversion within 30 min, whereas MMA achieved only 19% under identical conditions. These results indicate that carvone is more compatible with methacrylate-based systems and is therefore better suited as a nonreactive diluent for methacrylate formulations than for acrylate-based systems. By integrating olfactory responsiveness, antimicrobial functionality, and renewable feedstocks, this platform enables 4D-printed structures for healthcare, consumer products, and interactive devices.