Construction of TiC MXene based fire resistance nanocoating on flexible polyurethane foam for highly efficient photothermal conversion and solar water desalination.

In this work, a bilayer nanocoating was constructed on the surface of flexible polyurethane (FPU) foam with TiC MXene and polyethyleneimine-modified silica nanoparticles (mSiO-NP@PEI) through layer-by-layer self-assembly technology, successfully obtaining modified flexible polyurethane composites (MFPU) with excellent flame retardancy, photothermal conversion and solar water desalination properties. The structure and morphology of MFPU foams were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Transmission electron microscope (TEM) and Scanning electron microscope (SEM). The MFPU with three coating cycles (MFPU3) had the best flame retardancy and smoke suppression performances, mainly in terms of decreased peak heat release rate (pHRR), peak smoke production rate (pSPR) and total smoke production (TSP) by 71.3 %, 62.1 % and 74.5 %, respectively, compared to those of neat FPU. In addition, MFPU foams exhibited extraordinary light-to-heat conversion and solar water desalination capabilities. MFPU3 could reach 120 °C in 138 s and its steam conversion efficiency η was as high as 89.6 %, which was 116.0 % higher than that of unmodified foam and had a 262.8 % increase over pure water. The flame retardant MFPU foams with excellent photothermal conversion efficiency will exhibit great application potential in solar water desalination and power generation.