Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/214378

Title

Surface chemistry and moisture sorption properties of wood coated with multifunctional alkoxysilanes by sol-gel process

Author(s)

Tshabalala, Mandla A.;  Kingshott, Peter;  VanLandingham, Mark R.;  Plackett, David

Abstract

Sol-gel surface deposition of a hydrophobic polysiloxane coating on wood was accomplished by using a mixture of a low molecular weight multifunctional alkoxysilane, methyltrimethoxysilane (MTMOS), and a high molecular weight multifunctional alkoxysilane, hexadecyltrimethoxysilane (HDTMOS). Investigation of the surface chemistry and morphology of the wood specimens by means of ATR-FTIR, energy-dispersive X-ray analysis, X-ray photo-electron spectroscopy, SEM, and atomic force microscopy indicated that the sol-gel process results in deposition of polysiloxane networks that are bonded to the wood by polycondensation with surface hydroxyl groups. The surface hydroxyl groups involved in the bonds appear to be located predominantly on the cellulose component of the wood. The sol-gel deposit on the wood substrates lowered the rates of water and water vapor sorption. The low molecular weight MTMOS apparently penetrated the outer surface layers of the wood and condensed with hydroxyls that may not be readily accessible to the high molecular weight HDTMOS. Once attached to such sites, it is reasonable to assume that some of these surface derivatives of MTMOS condensed with other molecules of MTMOS and HDTMOS with a long hydrocarbon chain to form a polysiloxane network that is hydrophobic. The ultimate effect of the sol-gel deposit can therefore be regarded as not only to decrease the surface concentration of hydrogen-bonding sites, but also to stereochemically hinder the formation of hydrogen bonds between such sites and water molecules.

Publication type

Journal article

Source

Journal of Applied Polymer Science, Vol. 88, no. 12 (Jun 2003), pp. 2828-2841

Publication year

2003

FOR Code(s)

03 Chemical Sciences;  09 Engineering

Keyword(s)

Atomic force microscopy;  Cellulose;  Coatings;  Hydrogen bonds;  Hydrophobicity;  Moisture;  Morphology;  Polycondensation;  Polymer networks;  Polysaccharides;  Polysilicones;  Scanning electron microscopy;  Silanes;  Silicone coatings;  Sorption;  Stereochemistry;  Surface;  Surface chemistry;  Wood;  X ray photoelectron spectroscopy

Publisher

John Wiley & Sons

ISSN

0021-8995

Publisher URL

http://dx.doi.org/10.1002/app.12142

Copyright

Copyright © 2003 Wiley Periodicals, Inc.

Peer reviewed