Daniel Montplaisir

Advances in cellulose chemistry - Microwave-assisted synthesis of propargylcellulose in aqueous medium

A fast and simple reaction activated by microwave irradiation permits the “green synthesis” of propargylcellulose in an aqueous alkaline medium. The influence of several reaction parameters such as amount of propargyl bromide, reaction time or microwave activation on the reaction efficiency are reported herein. The propargylcellulose samples obtained, with degrees of substitution (DS) from 0.35 to 1.88, were characterised by means of FTIR and NMR spectroscopy.

Tosylcellulose synthesis in aqueous medium

p-Toluenesulfonyl cellulose was prepared by reacting cellulose in aqueous medium, instead of via traditional routes, which involve the use of DMAc/LiCl, or more recently, ionic liquids. The influence of several parameters on the reaction efficiency has been studied; amount of tosylchloride, presence of triethylamine, reaction time and use of sodium hydroxide or sodium chloride. The resulting p-toluenesulfonyl cellulose samples were characterized by means of FTIR and NMR spectroscopy. The effects of solvent on the crystalline change during tosylation were investigated by X-ray diffraction (XRD). The degree of substitution (DS) was determined by 1H NMR and confirmed by X-ray photoelectron spectroscopy (XPS). Tosylcelluloses with DS from 0.1 to 1.7 have been prepared.

Predicting the most appropriate wood biomass for selected industrial applications: comparison of wood, pulping, and enzymatic treatments using fluorescent-tagged carbohydrate-binding modules

BackgroundLignocellulosic biomass will progressively become the main source of carbon for a number of products as the Earth’s oil reservoirs disappear. Technology for conversion of wood fiber into bioproducts (wood biorefining) continues to flourish, and access to reliable methods for monitoring modification of such fibers is becoming an important issue. Recently, we developed a simple, rapid approach for detecting four different types of polymer on the surface of wood fibers. Named fluorescent-tagged carbohydrate-binding module (FTCM), this method is based on the fluorescence signal from carbohydrate-binding modules-based probes designed to recognize specific polymers such as crystalline cellulose, amorphous cellulose, xylan, and mannan.ResultsHere we used FTCM to characterize pulps made from softwood and hardwood that were prepared using Kraft or chemical-thermo-mechanical pulping. Comparison of chemical analysis (NREL protocol) and FTCM revealed that FTCM results were consistent with chemical analysis of the hemicellulose composition of both hardwood and softwood samples. Kraft pulping increased the difference between softwood and hardwood surface mannans, and increased xylan exposure. This suggests that Kraft pulping leads to exposure of xylan after removal of both lignin and mannan. Impact of enzyme cocktails from Trichoderma reesei (Celluclast 1.5L) and from Aspergillus sp. (Carezyme 1000L) was investigated by analysis of hydrolyzed sugars and by FTCM. Both enzymes preparations released cellobiose and glucose from pulps, with the cocktail from Trichoderma being the most efficient. Enzymatic treatments were not as effective at converting chemical-thermomechanical pulps to simple sugars, regardless of wood type. FTCM revealed that amorphous cellulose was the primary target of either enzyme preparation, which resulted in a higher proportion of crystalline cellulose on the surface after enzymatic treatment. FTCM confirmed that enzymes from Aspergillus had little impact on exposed hemicelluloses, but that enzymes from the more aggressive Trichoderma cocktail reduced hemicelluloses at the surface.ConclusionsOverall, this study indicates that treatment with enzymes from Trichoderma is appropriate for generating crystalline cellulose at fiber surface. Applications such as nanocellulose or composites requiring chemical resistance would benefit from this enzymatic treatment. The milder enzyme mixture from Aspergillus allowed for removal of amorphous cellulose while preserving hemicelluloses at fiber surface, which makes this treatment appropriate for new paper products where surface chemical responsiveness is required.

Microfibrillated cellulose with sizing for reinforcing composites with LDPE

Microfibrillated cellulose (MFC) fibers were acylated by the sizing agent, alkenyl succinic anhydride (ASA) reagent in an aqueous medium, by simple impregnation. The chemical modification was confirmed by Fourier transform infrared spectroscopy and solid-state 13C NMR. All the samples were combined with low-density polyethylene and the morphology, thermal properties, mechanical properties and water absorption behavior of the ensuing composites were investigated. The chemical modification of the MFC with ASA improved the interfacial adhesion with the matrix and hence the mechanical properties of the composites while decreasing their water uptake capacity. In addition, it was shown that the degree of substitution strongly influenced the performance of the composites.