Integrating Photothermal-Responsive Shape Memory and Self-Healing Polymers in 4D-Printed Thermally Comfortable Smart Wearables

Inspired by nature, photothermal-responsive shape memory and self-healing polymers demonstrate capabilities in self-sustainable and multifunctional actuation, which is highly promising for future smart wearables. However, their advancement in smart wearables is impeded by excessive surface heat generated from photothermal fillers, resulting in significant thermal discomfort for users. Herein, a high-performance photothermal-responsive shape memory and self-healing polymer is derived from a series of poly(urethane methacrylate)s (PUMAs) by meticulously modulating their microstructure and properties through the isocyanate-to-hydroxyl ratio and reactive diluent content. Its intrinsic photothermal properties, excellent shape recovery (ca. 98.7%), and high self-healing efficiency (ca. 93.4%) enable synergistic coupling effect of autonomous deformation recovery and crack healing. More importantly, its actuation temperature (ca. 35.2 °C) is much lower than the thermal discomfort threshold temperature range of the human body (ca. 43–48 °C), thereby enabling sunlight-induced shape memory and self-healing actuation at thermal comfort temperatures. In addition, end-functionalization of methacrylate moieties grants photocurability for integration in vat photopolymerization-based printing of smart wearables. The contribution of this work is centered on the low surface temperature achieved through photothermal effect (ca. 37.5 °C), which is adequate to trigger shape memory effect and self-healing while remaining within the thermal discomfort threshold temperature of the human body, offering an advantage over comparable materials. A four-dimensional (4D)-printed sneaker is created to demonstrate its shape memory and self-healing abilities under simulated and natural sunlight while simultaneously achieving thermal comfort. This work establishes a cornerstone for developing next-generation multifunctional smart wearables with end-user personalization and superior comfort of wear.