Preparation of thermo-responsive superhydrophobic TiO2/poly(N-isopropylacrylamide) microspheres

► The thermo-responsive superhydrophobic microspheres are obtained via a process that combines sol-gel method and ATRP. ► The reversible switch between hydrophilicity and superhydrophobicity of TiO2/PNIPAM composites is rapid and significant. ► The as-prepared composites offer us an opportunity to develop cost-effective smart materials. Here we reported a facile method that combined sol–gel and surface-initiated atom transfer radical polymerization (ATRP) to prepare thermo-responsive superhydrophobic TiO2/poly(N-isopropylacrylamide) microspheres with core–shell structure. The surface coated with microspheres show hydrophilic properties (CA=90.5±2.3°) at 27°C, it changes to superhydrophobicity (CA=150.2±2.3°) while the temperature rises up to 42°C. This performance is attributed to lower critical solution temperature (LCST) phenomenon of Poly (N-isopropylacrylamide). Five cycle measurements of water droplet reversible switch between hydrophilicity and superhydrophobicity were demonstrated temperature-responsive surface property. The changes were rapid and significant. The as-prepared particles have been characterized by scanning electron microscopy, transmission electron microscopy, thermal gravimetric analysis, FT-IR analysis, and dynamic light scattering.