N-octadecane infused TDI-PEG-grafted halloysite nanotube for thermal management of unidirectional moisture/breathable smart textiles

Porous materials are ideal carriers for preparing shape-stable composite phase change materials (CPCMs), with their pore size and capillary force determining the adsorption and fixation ability of phase change materials (PCMs). Herein, acid etching and polymer modification were used to enhance the adsorption efficiency of n-octadecane by halloysite nanotubes (HNTs) via vacuum impregnation. The maximum loading capacity of the two modified HNTs for n-octadecane was similar, while the shape stability of the CPCMs prepared by grafting was superior, with a latent heat energy of 64.72 J·g-1. These CPCMs were applied to the cotton fabric to form a hybrid layer via wet coating, which maintained an air permeability of 5.97% and a photothermal conversion efficiency of 32.4%. Moreover, the coating layer also displayed hydrophobicity and unidirectional moisture performance. The smart fabric exhibited excellent heat storage and photothermal conversion performance, with the surface temperature being 15.2°C higher than that of raw cotton after sunlight irradiation and absorption saturation, while the cooling time to room temperature was extended by 410 s, highlighting its smart temperature-regulating properties. Overall, this study provided a novel approach for developing smart fabrics with optimal photothermal conversion efficiency.