Novel near-infrared light-induced shape memory nonionic waterborne polyurethane composites based on iron gallate and dynamic phenol-carbamate network

Shape memory polymers with multi-responsiveness, especially for intelligent materials derived from green and renewable monomers, have recently drawn great attention resulting from the environmentally friendly feature. Herein, iron gallate (GA-Fe) nanoparticles with excellent photothermal conversion ability were prepared by simply mixing gallic acid solution and FeCl3 solution based on coordination chemistry, and subsequently were incorporated into the gallic acid-based nonionic waterborne polyurethane (GWPU) matrix to prepare functionalized nanocomposites. Taking advantage of the desirable crystallization ability of GWPU to enable the nanocomposites with shape memory performance, and GA-Fe nanoparticles serving as photothermal fillers, outstanding near-infrared (NIR) light induced shape memory behavior was achieved. Meanwhile, the NIR light triggered shape recovery ratio and speed improved significantly with the increase of GA-Fe nanoparticles loading. Importantly, due to the better electrolyte stability of nonionic GWPU dispersions allowing GA-Fe nanoparticles with good compatibility to be well dispersed, the nanocomposite containing 0.3 wt% of GA-Fe nanoparticles could recover to its original shape from temporary shape within 1 min under irradiation of NIR light, and the corresponding surface temperature could rise above 70 °C. Further, by virtue of the dynamic nature of phenol-carbamate network, the permanent shape of the nanocomposites could be reshaped via topological rearrangement. Because of the excellent photothermal performance, simple preparation method, good dispersibility and easily available raw materials, GA-Fe nanoparticles have great application potential in preparing novel stimulus-responsive nanocomposite materials with versatile functions as efficient and environmentally friendly photothermal converters.