Methylation-triggered fractionation of lignocellulosic biomass to afford cellulose-, hemicellulose-, and lignin-based functional polymers via click chemistry

Abstract

This paper reports a new concept for the biorefinery of lignocellulosic biomass where the derivatisation and fractionation of lignocellulose are accomplished at the same time. Methylation of sawdust of Larix kaempferi (Lamb.) Carrière in dimethyl sulfoxide/tetrabutylammonium fluoride followed by fractionation provided three different polymeric derivative fractions: methylated cellulose, lignin, and hemicellulose. An aqueous solution of the methylated hemicellulose fraction was amphiphilic and possessed surface activity similar to that of industrially-produced methylcellulose. The azido-functionalised methylated cellulose and lignin fractions reacted with peracetyl propargyl β-cellobioside via Huisgen 1,3-dipolar cycloaddition followed by the removal of acetyl groups to yield a methylcellulose-block-cellobiose and methylated lignin-graft-cellobiose, respectively. An aqueous solution of diblock methylcellulose analogue, methylcellulose-block-cellobiose, formed thermoreversible supramolecular hydrogels near human body temperature. Methylated hemicellulose exhibited amphiphilic properties and acted as a surfactant. Methylated lignin-graft-cellobiose formed nanoparticles. Three major components in lignocellulosic biomass, cellulose, hemicellulose, and lignin, were successfully converted into three different functional materials.