Endowment of omniphobicity and exceptional bendability to a wear-resistant POSS coating

Coating of a new polyhedral oligomeric silsesquioxane, GMPOSS bearing two 3-glycidyloxypropyl (G) and six 3-methacryloxypropyl (M) groups, is highly wear-resistant but has no oil-or water-repellency and limited bend -ability. To render omniphobicity, perfluorinated poly(propylene oxide) (FP) bearing a terminal carboxyl group (FP-COOH) is grafted onto a fraction of the GMPOSS molecules to yield F-GMPOSS, a mixture of GMPOSS and GMPOSS-FP. Subsequent photocuring of a liquid film of F-GMPOSS that contains 2.6 wt% of fluorine produces a highly transparent coating with superior dynamic de-wetting properties. To improve the coating's bendability, an innovative method for composite making is developed. A flexible porous poly(vinylidene fluoride-co-hexa-fluoropropylene) (PVDFP) scaffold is prepared first on a poly(ethylene terephthalate) (PET) substrate. F-GMPOSS containing photoinitiators are then infused into the PVDFP pores and photocured to produce a composite coating. At a thickness of 20 mu m, the composite can fold, without crack or peel, 500 times on either the inner or outer side of its PET substrate around a rod of a diameter of 2 mm. The coating also has a transmittance of 95 +/- 2% at 500 nm, a low surface energy of 11.8 +/- 1.6 mJ/m2, and an impressive hardness of 0.80 +/- 0.02 GPa. Its superior ink contraction capability remains intact after 100 abrasions with steel wool. While the methods for rendering antismudge properties and flexibility can be used to prepare other materials and coatings, the F-GMPOSS coating and the F-GMPOSS/PVDFP composite coating are of practical value and may be used as the encapsulating layer for foldable touchscreens, for example.

Automated summary

A new polyhedral oligomeric silsesquioxane coating modified with perfluorinated poly(propylene oxide) and developed using an innovative method for composite making has been shown to have high wear-resistance, omniphobicity, and superior bendability. The resulting composite coating has impressive properties including high transparency, low surface energy, exceptional hardness, and ink contraction capability. These coatings are of practical value and may find applications in foldable touchscreens.