Superhydrophobic waxy-dendron-grafted polymer films via nanostructure manipulation

To imitate the superhydrophobicity of salient epicuticular wax on lotus leaves (hereafter "Lotus effect"), waxy dendrons were synthesized and subsequently grafted on amine-containing polystyrenes. To achieve a low surface energy and a specific surface morphology, the waxy dendron design is composed of two parts-the focal part possessing plenty of hydrogen bonding sites, and the peripheral part rich in van der Waals forces. The enhanced van der Waals force accompanied with increasing generation of dendrons helps induce self-assembly and phase separation in the preparation process of the polymer films. By different coating processes, three different films (thin film, honeycomb-like film, and three-dimensional rod-co-valley-like film) were obtained with contact angles of 95 degrees, 130 degrees, and 165 degrees, respectively. The three-dimensional rod-co-valley film samples were able to imitate the superhydrophobic property (i.e. Lotus effect), as well as utilize the built-in strong hydrogen bonds to adhere water droplets on surfaces or substrates.