Condensed tannins from pine bark: A novel wood surface modifierassisted by laccase

FILGUEIRA, D.; MOLDESA, D.; FUENTEALBA, C.; GARCÍA, D.
Industrial Crops and Products, Volume 103, September 2017, Pages 185-194

DOI: 10.1016/j.indcrop.2017.03.040

Abstract

Condensed tannins (CTs) from Pinus radiata bark were chemically modified with propylene oxide in order to improve their hydrophobicity for beech wood (Fagus sylvatica L.) surface modification. CTs and hydroxypropylated tannins (HPTs) were used for laccase catalyzed wood surface grafting at different pH (3, 7, and 10) for the first time. The impact of the modification on the wood surfaces was evaluated by FT-IR mapping, Confocal Fluorescence Emission Microscopy (CFEM) and Water Uptake Behavior (WUB). The effect of the enzyme was evaluated by measuring the total phenolic content (TPC) of the washing solution. The leaching of CTs and HPTs was decreased due to the enzyme activity. HPTs showed up to 30% less leaching after the surface coating in comparison to CTs. CFEM results suggested that the best grafting conditions occurred at pH 10, for both polyphenols used. CT- and HPT-treated samples increased their surface hydrophobicity, which resulted in a lower water uptake, during the first 12 h. The results highlighted that the enzymatic grafting of CTs and HPTs on beech wood surfaces can be a promising strategy for the functionalization of lignocellulosic materials in order to provide new properties for a wide range of applications.

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