Title: Multifunctional Hard Yet Flexible Coatings Fabricated Using a Universal Step-by-Step Strategy

Abstract: Hard yet flexible coatings with multi-functionalities are useful for  foldable displays and marine industries but rare. In this study, a  highly cross-linked multifunctional hybrid coating with ceramic-like  hardness and polymer-like flexibility is reported. The coating is  prepared via a step-by-step strategy, where two types of  epoxy-oligosiloxane nanoclusters are first synthesized by sol-gel  chemistry, and amine-terminated curing agents are used to cross-link  them at room temperature. The coating is highly transparent (>92%  transmittance), hard (6-7H), and flexible (10 mm bending diameter)  because of the unique combination of siloxane nanoclusters and polymer  networks. Meanwhile, since the coating contains fouling-resistant  telomer and low-surface-tension liquid lubricant polydimethylsiloxane  (PDMS), it exhibits excellent anti-biofouling and self-cleaning  properties. The results indicate that the mechanical and antifouling  properties of the coating can be easily tuned and prove that the  step-by-step strategy is a promising and universal method. The novel  coatings can meet the needs of applications in foldable displays, marine  industries, and other fields.