Cellulose dissolution in different solvents

Abstract

Cellulose is the most abundant renewable biopolymer on the earth. It finds applications in many important commercial areas such as fibers, packaging materials and biofuel production and has potential to alleviate the existing dominance of fossil-based exhaustible resources in the production of these materials. However, preparation of most of these products from cellulose requires a challenging first step of its dissolution. Owing to its high molecular weight and semi-crystalline structure, dissolution of cellulose is difficult. Current industrial processes involve use of high temperature and harsh chemicals leading to high cost, energy inefficiency and high environmental impacts. Efficient cellulose dissolution in cost saving and mild conditions is highly desirable.
Cellulose dissolution in two different solvent systems namely N,N-dimethylacetamide /lithium chloride (DMAc/LiCl) and 1-butyl-3-methylimidazolium acetate/N,N-dimethylacetamide (BMIMAc/DMAc)was studied with an overall objective of optimizing its dissolution at mild conditions and preparation of regenerated materials with desirable properties. Freeze-drying pretreatment of microcrystalline cellulose (MCC) facilitated its dissolution at mild conditions in DMAc/LiCl solvent system. Film with desirable properties such as good optical transparency, homogeneity and stability was prepared from solution of 5% concentration of freeze-dried MCC in DMAc/LiCl. Dissolution of high molecular weight cellulose (DP >4000) in ionic liquid based solvent, 1-butyl-3-methylimidazolium acetate/N,N-dimethylacetamide (BMIMAc/DMAc) at ambient conditions was investigated. High molecular weight cotton cellulose was fully dissolved at concentration between 3 and 5% at ambient conditions. Highly porous regenerated film could be prepared from solution of well dissolved high molecular cotton cellulose. The potential of further improvement of dissolution of high molecular weight cellulose in BMIMAc/DMAc at ambient conditions was investigated by employing sulfuric acid hydrolysis and cryogenic grinding to the cotton cellulose. No improved dissolution of hydrolyzed cotton cellulose and cryogenically ground cotton cellulose compared to the original cotton cellulose (not hydrolyzed) was observed.

Description

Keywords

Cellulose, Dissolution

Citation