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

A recently developed esterifi cation method in our laboratory was applied to permanent hydrophobization of wood surfaces. Specifi cally, the covalent attachment of fl uoroorganyl 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 modifi cation from 150 ° C to 120 ° C, or even to 70 ° C so that thermal decomposition of wood during modifi cation can be neglected. The modifi ed chips were analyzed by attenuated total refl ection – infrared and X-ray photoelectron spectroscopy. Covalent attachment of the fl uorobenzoic acids led to a very high, permanent hydrophobicity of the wood surface, documented by outstanding contact angles of up to 143 ° .