Direct dissolution of lignocellulosic biomass by malonic acid-DBU protonic ionic liquid and preparation of high-performance all-biomass films†

Abstract

Renewable biomass resources have attracted a lot of attention from researchers due to the energy crisis and environmental pollution. The dissolution of biomass is an important topic of biomass refining, so it is crucial to design and develop green solvents. Among them, protonic ionic liquids (PILs) are potential solvents due to the advantages of variety, simple preparation, and low cost. In this work, the direct dissolution of a wide range of biomasses was achieved by using novel malonic acid-DBU PIL. Unlike previous dissolution solvents, this work not only obtained excellent dissolution results (10.2 wt%) but also analyzed in detail the effect of components in the biomass on the dissolution result. The comparative analysis of twelve biomasses summarised the regularity of the components in biomass affecting solubility, which provided instructive information for the field of dissolving biomass by ionic liquids. At the same time, the different types of biomass solutions were practically applied to achieve efficient utilization of resources. The high-performance biomass films with structural integrity, sufficient thermal stability, high tensile strength (107 MPa), excellent UV-blocking (99%), strong water stability, and biodegradability can be prepared by a simple process of coagulation bath regeneration and hot pressing. Moreover, the biomass films retained most of the valuable lignocellulosic fraction, effectively avoiding the waste of biomass resources. In summary, this work achieves the dissolution of biomass by using novel malonic acid-DBU PIL and simultaneously prepares high-performance biomass films, which provide a simple and easy pathway for the conversion and application of biomass.