Flexible Alginate-Based Phase Change Films by Ionic Cross-Linking Engineering for Efficient Thermal Management

Abstract Flexible phase change materials (PCMs) are pivotal for mitigating overheating in compact electronics, yet are often constrained by solid-state rigidity, leakage, and low thermal conductivity. Herein, we present an anion-modulated ionic cross-linking strategy to fabricate flexible and leakage-proof alginate-based composite films with poly(ethylene glycol) (PEG) as a phase change component. The synergistic effect of alginate-calcium ion cross-linking and anion-enhanced polymer flexibility endows the film with excellent mechanical toughness, achieving a toughness of 1.30 MJ/m3. The flexible PCMs exhibit a high latent heat of 125.02 J/g, attributed to the in situ encapsulation of PEG. Furthermore, the incorporation of hexagonal boron nitride enhances the thermal conductivity by 176% compared to that of pure PEG. In simulated chip thermal management tests, the phase change film can achieve a peak temperature reduction of 10.7 °C and an average thermal management performance of 10.3 °C during cycling, demonstrating its high efficacy and long-term stability. This work provides a facile and green pathway to develop high-performance flexible PCMs for efficient thermal management without additional power consumption.