Chemical improvement of surfaces. Part 2: Permanent hydrophobization of wood by covalently bonded fluoroorganyl substituents

Abstract

Abstract A recently developed esterification method in our laboratory was applied to permanent hydrophobization of wood surfaces. Specifically, the covalent attachment of fluoroorganyl substituents to wood hydroxy groups via benzotriazolyl-activated, substituted benzoic acids was in focus. Weight percent gain values from 10% to 28% were obtained on Scots pine (Pinus sylvestris) sapwood veneer chips. It proved feasible to lower the temperature for wood modification from 150°C to 120°C, or even to 70°C so that thermal decomposition of wood during modification can be neglected. The modified chips were analyzed by attenuated total reflection – infrared and X-ray photoelectron spectroscopy. Covalent attachment of the fluorobenzoic acids led to a very high, permanent hydrophobicity of the wood surface, documented by outstanding contact angles of up to 143°.