Organic/inorganic coating composites based on polyol-isocyanate/sol-gel system

Abstract

Organic/inorganic composites based on silane group functionalized polyol/sol-gel system were undertaken. The functionalized polyols of 30%, 50% and 70% degree functionalization was successfully prepared by reacting poly(2-hydroxyethyl methacrylate) (PHEMA) with 3-isocyanatopropyl (triethoxysilane). Coating formulation was prepared by thoroughly mixing functionalized PHEMA(s) with 4,4'-diphynylmethane diisocyanate (MDI) in the present of p-toluenesulfonic acid as a catalyst. The coating solutions were applied onto polycarbonate sheet and acrylic sheet to achieve film thickness of 30 micron, then followed by curing at temperature of 120 ํC for 3 hours. Smooth and transparent film obtained indicated no phase separation between organic and inorganic compounds. FT-IR and solid state 29Si-NMR analysis of coating showed that the reaction of HEMA hydroxyl group with MDI produced organic network while sol-gel reaction among siloxyl pendant groups led to the formation of inorganic siloxane network. Surface performance of coated PC was markedly improved. The finding results also revealed that inorganic component content played an important role in improving the abrasion resistance of coated substrate.