Recent advances in superhydrophobic polyurethane: preparations and applications

Even though polyurethane (PU) has been widely applied, its superhydrophobicity is inadequate for certain applications. As such, the development of superhydrophobic polyurethane (SHPU) has recently attracted significant attention, with numerous motivating reports in recent years. However, a comprehensive review that summarizes these state-of-the-art developments remains lacking. Thus, this review aims to fill up this gap by reviewing the recent preparation methods for SHPU based on superhydrophobic theories and principles. Three main types of methods used in promoting the hydrophobicity of PU are emphasized in this review; (1) incorporation of silicide or fluoride to lower the surface energy, (2) creation of micro/nano-scale rough surfaces by electrospinning or grafting of nanoparticles, and (3) integrating the earlier two methods to develop a synergistic approach. Furthermore, this review also discussed the various applications of SHPU in oil spill treatment, protective coating, self-healing materials and sensors.