Modified Melamine Foam-Based Flexible Phase Change Composites: Enhanced Photothermal Conversion and Shape Memory Properties

Phase change materials (PCM) have broad application prospects in energy utilization and thermal management due to their high heat storage capacity. Current research focuses on solving the problems of easy leakage and slow heat transfer during the phase change of PCM. However, problems such as strong rigidity and weak light absorption also severely limit their practical applications. In this work, the RHTC-BN compound was prepared by sonicating carboxy-rich carbon (RHTC) and boron nitride (BN). The flexible (RHTC-BN)/MF was prepared by coating BN on melamine sponges (MF) skeleton using RHTC as a bridge. (RHTC-BN)/MF/PEG PCM was prepared by vacuum impregnation polyethylene glycol (PEG) into (RHTC-BN)/MF. The high porosity and low density of (RHTC-BN)/MF give (RHTC-BN)/MF/PEG PCM excellent leak-proof performance and high latent heat (151.4 J/g), and the optimal loading of PEG is 92.3 wt %. The bridging effect of RHTC drives the formation of a cross-interconnected 3D thermal conductivity network in (RHTC-BN)/MF, which endows (RHTC-BN)/MF/PEG PCM with high thermal conductivity (0.92 W m–1 K–1). Research proved that the flexibility of (RHTC-BN)/MF sponge and the phase change behavior of PEG does not just provide (RHTC-BN)/MF/PEG PCM with thermally driven shape memory (recovery speed of about 355 s) and self-adhesive function. Moreover, the photothermal conversion energy storage efficiency is as high as 91.5%. It has excellent potential in solar energy storage systems and provides a pathway for developing thermally responsive shape adaptive devices for energy storage applications.