Strong substrate adhesive and self-cleaning polysilsesquioxane coating with excellent mechanical property and chemical stability

Abstract

Developing hard yet flexible organic-inorganic hybrid coating with enhanced substrate adhesion and self-cleaning ability is of the great interest to many application scenarios such as foldable display devices. To this end, herein polysilsesquioxanes (PGSQ-F) with perfluorinated alkyl and epoxy moieties are synthesized and then coated on the amine-modified substrates (glass and PET) to create strong interfaces by the epoxy-amine reaction. After UV curing in the presence of a photoinitiator, the epoxy group of PGSQ-F undergoes a ring-opening polymerization to form a highly cross-linked network. The adhesion of PGSQ-F coating to the treated glass and PET substrates is as high as 3.9 ± 0.4 MPa and 1.5 ± 0.3 MPa, respectively. The high adhesive strength enhances the coating's resistance to various solvents. Moreover, the obtained coatings display the high pencil hardness (9H pencil hardness), excellent flexibility (1 mm bending diameter) and high transmittance (89.5 % 550 nm). In addition, the perfluorinated alkyl chains from PGSQ-F spontaneously aggregate onto the coating surface, endowing the coating with omniphobic feature, with water and n-hexane contact angle of 115.1 ± 0.7° and 70.2 ± 0.5°, respectively, which account for their outstanding antismudge and self-cleaning properties.