Preparation of Water-Resistant Antifog Hard Coatings on Plastic Substrate

摘要

A novel water resistant antifog (AF) coating fornplastic substrates was developed, which has a specialnhydrophilic/hydrophobic bilayer structure. The bottom layer,nacting both as a mechanical support and a hydrophobic barriernagainst water penetration, is an organic−inorganic compositencomprising colloidal silica embedded in a cross-linked networknof dipentaethritol hexaacrylate (DPHA). Atop this layer, an AFncoating is applied, which incorporates a superhydrophilicnspecies synthesized from Tween-20 (surfactant), isophoronendiisocyanate (coupling agent), and 2-hydroxyethyl methacrylaten(monomer). Various methods, e.g., FTIR, SEM, AFM,ncontact angle, and steam test, were employed to characterize the prepared AF coatings. The results indicated that the size and thencontinuity of the hydrophilic domains on the top surface increased with increasing added amount of T20, however, at thenexpense of hardness, adhesiveness, and water resistivity. The optimal T20 content was found to be 10 wt %, at which capacity thenresultant AF coating was transparent and wearable (5H, hardness) and could be soaked in water for 7 days at 25 °C withoutndowngrading of its AF capability.