Synthesis of water vapor barrier membrane by coating of poly(vinyl alcohol) substrate with poly(tert‐butyl acrylate)‐silica nanocomposite

Abstract

AbstractTo prepare a water vapor barrier membrane, organic/silica nanocomposites were used with perhydropolysilazane (PHPS) and poly(tert‐butyl acrylate) (P(tBA)) or poly(tert‐butyl acrylate‐co‐2‐hydroxyethyl methacrylate) (TBAH) on a poly(vinyl alcohol) (PVA) substrate. Water vapor permeability coefficient, Q, of the coated PVA substrates was measured. To prevent crack formation in the organic/silica nanocomposite layer, P(tBA) or TBAH with lower Tg than that of PVA was inserted as a stress relaxation layer between the PVA substrate and the composite layer. The insertion of the stress relaxation layer drastically decreased the Q value. The lowest Q value was observed especially when TBAH was inserted between TBAH/silica nanocomposite layer and the PVA substrate. Observation with a scanning electron microscope (SEM) did not show any crack both in the composite layer and near the interface between layers. It would be due to the good compatibility of the TBAH stress relaxation layer to the TBAH/silica nanocomposite layer and to the PVA substrate. Copyright © 2008 John Wiley & Sons, Ltd.