Synergistic thermally triggered dissolution and evaporative cooling in a composite hydrogel for high‑efficiency electronics cooling

Novel dual‑mode cooling synergy：Thermosensitive microcapsule‑triggered dissolution heat absorption coupled with passive evaporative cooling. • Fast, on‑demand response: PNVCL shell collapse at ~38 °C enables rapid heat uptake during thermal shock. • h‑BN network for rapid heat transport: Bypasses the thermal conduction bottleneck of polymer shells in traditional PCM microcapsules. • Multifunctional integration: Self‑healing, high stretchability, strong adhesion, and moisture absorption in one material. Efficient cooling materials are essential for the reliable operation of high-power devices. Herein, a multifunctional composite hydrogel (PBTPB) is fabricated by integrating PNVCL@NH 4 Cl thermosensitive microcapsules and an h-BN thermal conduction network into a polyvinyl alcohol/borax/tannic acid (PVA/borax/TA) matrix. The h-BN network enhances thermal conductivity by providing rapid heat transport pathways. Upon reaching a critical temperature, the microcapsules release NH 4 Cl, whose dissolution actively absorbs heat, while continuous water evaporation from the hydrogel contributes to passive cooling. Experimental results show that PBTPB exhibits excellent heat dissipation performance. In simulated chip cooling tests, a temperature plateau (61–67 °C) lasting 1170 s is achieved, significantly delaying chip overheating. In hot water cooling experiments, the PBTPB-covered test tube reaches a final temperature 14 °C lower than that under natural cooling. Moreover, PBTPB possesses outstanding mechanical properties (elongation at break: 1163%), rapid self-healing (91% efficiency within 10 min), and strong interfacial adhesion (3.2 kPa to copper), ensuring close contact with heat sources and long-term reliability. Thus, this composite hydrogel holds great promise for cooling applications. Download: Download high-res image (127KB) Download: Download full-size image