Influence of the Supramolecular Structure and Physicochemical Properties of Cellulose on Its Dissolution in a Lithium Chloride/N,N-Dimethylacetamide Solvent System

• Published in: Biomacromolecules Vol. 6; no. 5; pp. 2638 - 2647
• Main Authors: Ramos, Ludmila A, Assaf, José M, El Seoud, Omar A, Frollini, Elisabete
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.09.2005
• Subjects: Acetamides - chemistry; Adsorption; Animals; Applied sciences; Biocompatible Materials - chemistry; Cattle; Cellulose - chemistry; Cellulose and derivatives; Chromatography; Chromatography, High Pressure Liquid; Cross-Linking Reagents - chemistry; Entropy; Exact sciences and technology; Hot Temperature; Hydrocarbons - chemistry; Hydrogen-Ion Concentration; Hydrolysis; Infusions, Intravenous; Kinetics; Lithium Chloride - chemistry; Magnetic Resonance Spectroscopy; Methane - analogs & derivatives; Methane - chemistry; Microscopy, Electron, Scanning; Models, Chemical; Natural polymers; Nitrogen - chemistry; Physicochemistry of polymers; Polyethylene Glycols - chemistry; Polymers - chemistry; Rats; Solvents; Spectrophotometry; Succinic Acid - chemistry; Time Factors; Trypsin - chemistry; Ultraviolet Rays; X-Ray Diffraction; Organic solution; Pore size; Cellulose; Property structure relationship; Kinetics; Crystallinity; Rate constant; Experimental study; Dissolution; Activation energy; Saline solution
• ISSN: 1525-7797; 1526-4602
• DOI: 10.1021/bm0400776

The present work deals with the effects of structural variables of celluloses on their dissolution in the solvent system LiCl/N,N-dimethylacetamide, LiCl/DMAc. Celluloses from fast growing sources (sisal and linters), as well as microcrystalline cellulose (avicel PH-101) were studied. The following structural variables were investigated:  index of crystallinity, I c; crystallite size; polymer porosity; and degree of polymerization determined by viscosity, DPv. Mercerization of fibrous celluloses was found to decrease DPv, I c, the specific surface area, and the ratio pore volume/radius. The relevance of the structural properties of cellulose to its dissolution is discussed. Rate constants and activation parameters of cellulose decrystallization, prior to its solubilization, have been determined under nonisothermal conditions. The kinetic parameters calculated showed that dissolution is accompanied with small, negative enthalpy and a large, negative entropy of activation.