Surface wrinkling and functionalization of organic coatings via diffusion of reactive molecules

Unique pattern morphologies created by surface instability are a versatile platform for controlling surface functionality. In this work, simultaneous surface wrinkling and hydrophobization of organic coatings by directly reacting with diffused propyl trichlorosilane (PTCS) from gas phase was demonstrated. By varying the initial coating type, various surface morphologies were obtained, showing different interactions with water droplets, demonstrating the high tunability of the method to achieve important surface functions, including rose petal and lotus effects. It was found that reaction between the absorbed water in the coating caused the hydrolysis of PTCS and their subsequent self-condensation to form siloxanes within the coating, which contributed to the large volume expansion and eventually triggered the wrinkling process. This method is independent of the substrate type and offers a great advantage in producing functional coatings using eco-friendly, VOC-free solutions.