Homogeneous Transesterification of Sugar Cane Bagasse toward Sustainable Plastics

Homogeneous esterification of lignocellulosic agro-forestry wastes is an efficient approach to transform the biomass into value-added biobased materials. However, the application of fatty acid anhydrides or acyl chlorides as esterified reagents would yield equivalent acids which lead to significant decomposition of lignocellulosic biomass. The present study proposed an alternative chemical approach to prepare bioplastics from lignicellulosic biomass. Sugar cane bagasse esters were prepared by transesterification with vinyl esters using 1-ethyl-3-methylimidazolium acetate as duel solvent and activator. Solution-stated NMR studies suggested that the polysacchirides were highly reactive during the homogeneous transesterification. The chemical mechanism of the transesterification was demonstrated to be a carbene mechanism, which subsequently transferred into the intermediate of 2-alkanoyl-dialkylimidazolium. The as-prepared sugar cane bagasse esters were found to be solvable in common solvents. Bioplastic films were prepared by solution casting. Scanning electron microscopy and tensile testing studies showed that the sugar cane bagasse ester films were comparable to those of cellulose fatty esters.