Date of Award
Summer 2013
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Chemistry
First Advisor
Tran, Chieu D.
Second Advisor
Hossenlopp, Jeanne M.
Third Advisor
Ryan, Michael D.
Abstract
A simple novel recyclable synthetic method was successfully developed for the synthesis of polysaccharide composite materials. The method involves the use of 1-butyl-3-methylimidazolium chloride [BMIm+Cl-], a simple ionic liquid, as the sole solvent. Naturally abundant and renewable materials such as cellulose (CEL) and chitosan (CS) were used for the preparation of the composite materials. CEL is the most abundant compound on earth, while CS is a product of deacetylation of chitin, which is the second most abundant material on earth. [BMIm+Cl-] is relatively non toxic, non volatile and stable over a wide range of temperature eliminating one of the major pathways to environmental contamination, making the method developed here environmentally friendly. In addition, at least 88% of the [BMIm+Cl-] used can be recovered for re-use, making the method much cheaper and green compared to methods employing traditional organic solvents. CEL and CS are attractive materials for their natural abundance, biodegradability and biocompatibility. While CEL is known for its superior mechanical properties, CS has been widely investigated and applied in adsorption of both organic and inorganic pollutants, antimicrobial, hemostasis, wound dressings and drug delivery systems. Composite materials made from CEL and CS are therefore expected to have combined advantages and qualities of both of these materials. Dissolution of both CEL and CS and successful regeneration was followed by X-ray diffraction. FT-IR, NIR and 13C CP MAS NMR spectroscopy were used to characterize the chemical composition of the regenerated composite materials. The morphology of the regenerated materials was evaluated using SEM. Results of tensile strength measurements showed that indeed, addition of CEL, a material of superior mechanical strength, to CS leads to considerable improvement in the strength of the materials. Up to 5 times increase in tensile strength was achieved by adding 80% CEL to CS. Doping the materials with cyclodextrins was found to not only improve their pollutant adsorption capacity, but also impart some size selectivity to the materials. Results of antimicrobial studies showed activity against a number of both gram negative and gram positive bacteria, while the blood absorption properties of these materials are comparable to commercially available products.