Hydrogen bonding in wood-based materials: an update
The contribution of hydrogen bonding to wood science and technology has been well recognized over the past century. The hydrogen bond is an important chemical characteristic contributing to wood-based material behavior and it also provides an important contribution to processing features of wood. However, the current understanding of hydrogen bond strength as a contributor to wood-based material behavior has not been updated in the wood literature. Wood-based material literature typically report hydrogen bond strengths ranging from 12.6 to 25.2 kJ/mol (3 to 6 kcal/mol) while newer data from the general chemistry field report hydrogen bond strengths up to 189 kJ/mol (45 kcal/mol), which are characteristic of covalent bond strength. In light of these new data regarding hydrogen bond strengths, it provides impetus to discuss the new understanding of hydrogen bond strength relative to wood-based material behavior. Recent developments in nanotechnology of renewable materials leading to the production and applications of cellulose nanomaterials with much higher surface areas and hydrogen bonding capacity also mandate revisiting our knowledge of the hydrogen bonding mechanism and strength.