Superhydrophobic, multi-responsive and flexible bottlebrush-network-based form-stable phase change materials for thermal energy storage and sprayable coatings

Multi-responsive form-stable phase change materials (FSPCMs) can convert various forms of energy to latent heat for storage and have attracted extensive attention. Superhydrophobic surfaces are garnering constant interest and can improve the long-term solar energy utilization and environmental adaptability of multi-responsive FSPCMs. However, a simultaneous demonstration of such functional integration is still a challenge due to the restriction of supporting materials. Herein, crosslinkable bottlebrush crystalline polysiloxanes (Si-0.75-18-x) having strong intermolecular forces with paraffin are used as super-flexible supporting materials to encapsulate paraffin via self-assembly and 3D networks. Multi-responsive phase change films are directly fabricated by spray-coating Si-0.75-18-x/paraffin solution with a dispersion of multi-walled carbon nanotubes (MWCNTs), followed by in situ curing. Herein, apart from fine affinity with Si-0.75-18-x, MWCNTs simultaneously enable tailored surface roughness, thermal/electrical conductivity and photo-thermal conversion. The proof-of-concept material (SiPa-160/CNTs-3) shows excellent latent heat, superhydrophobicity, photonic/thermal/electrical responses, shape variation ability, thermal recycling properties and stability. Strikingly, SiPa-160/CNTs-3 coatings can be large-scale constructed on varied substrates and have the potential for use in wearable devices, intelligent buildings, electronic devices and so on. This study broadens the advanced application and creates a whole new development platform for FSPCMs in energy conversion and storage.