Identifier

etd-09272010-162056

Degree

Doctor of Philosophy (PhD)

Department

Chemistry

Document Type

Dissertation

Abstract

Dissolution of chitosan in ionic liquids was accomplished. It has been shown that 1-butyl-3-methylimidazolium acetate (BMIMAc) is a better solvent than 1-butyl-3-methylimidazolium chloride (BMIMCl). Dissolution of chitosan in BMIMCl required a prior regeneration of chitosan from 1% acetic acid solution. In the case of BMIMAc, both dried chitosan and regenerated chitosan from acetic acid solution have been dissolved in a relatively short amount of time. While concentrations up to 2 wt% of chitosan in BMIMCl could be obtained, concentrations of 10 wt % of chitosan in BMIMAc were realized. Homogeneous phthalation and benzoylation of chitosan were achieved in these ionic liquids. According to FT-IR data both -OH and -NH2 groups of chitosan reacted with benzoyl chloride and phthalic anhydride, respectively. The reaction of chitosan with phthalic anhydride in the presence of a base or N-bromosuccinimide as catalyst and using ionic liquids as a solvent media was also studied. The presence of a base into system leads to an increase of the degree of substitution (DS = 0.41) of the functional groups of chitosan comparing with the reactions performed in the absence of a base (DS = 0.24), while the presence of a catalyst into system resulted in even higher increase of DS (0.85). The FT-IR data indicated that the hydroxyl groups of chitosan are being catalyzed to a greater extent than the amino groups. All the reactions products obtained in the presence of a catalyst were soluble in dimethyl sulfoxide and dimethylformamide. Chitosan-cellulose blends were prepared using BMIMAc as common solvent. Rheological measurements of polymeric solutions indicated the formation of a complex between chitosan and cellulose molecules. Films prepared from polymeric solutions were investigated by means of FT-IR, TGA, XRD and SEM measurements. The shifting of the band corresponding to –NH groups of chitosan from 1597 to 1565 cm-1 (FT-IR), the absence of diffraction peaks at 2è = 10.7 and 14.9o (XRD), the increased Ea for all polymeric blends (MTGA), and the presence of a homogeneous structure with no phase separation of the two polymers (SEM) serve as good evidence for the miscibility between chitosan and cellulose in the solid state.

Date

2010

Document Availability at the Time of Submission

Secure the entire work for patent and/or proprietary purposes for a period of one year. Student has submitted appropriate documentation which states: During this period the copyright owner also agrees not to exercise her/his ownership rights, including public use in works, without prior authorization from LSU. At the end of the one year period, either we or LSU may request an automatic extension for one additional year. At the end of the one year secure period (or its extension, if such is requested), the work will be released for access worldwide.

Committee Chair

Daly, H. William

Included in

Chemistry Commons

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