Studies On The Extraction, Modification And Fluorescence Properties Of Polymer Chitosan

Chitin is one of the most abundant nature resources, chitosan is deacetylated from chitin. As only alkali polysaccharide of the nature, chitosan has many special properties and applications. As most of present-day polymers are synthetic material, their biocompatibility and biodegradability are much more limited than those of nature polymers such as cellulose, chitin, chitosan and their derivatives. Chitin and chitosan are recommended as suitable functional materials, which is widely used in biology, medicine, foodstuff, cosmetics, adsorption heavy metals, film materials, agriculture, textile industry and so on. In order to develop the new resource of chitosan and find a new kind of fluorescence materials, we have studied the extracting technology of chitosan with waste mycelia, and the fluorescence properties of the chitosan derivatives by chemical modification were also first studied.This thesis composed of three parts, which are as follows:Part I. Review.It was look back of development history of the researching chitosan. The physical and chemical characterizations were especially reviewed. Their application of modified chitosan as function materials were discussed. Part II. The technology of extracting from waste mycelia.In this part we concerns on the preparing technology of chitosan with waste mycelia, which comes from citric acid industry. The major work was focused on the find of an optimum condition for the extrcting of chitin withthe acid and base as alternative method. The deacetlylation under 90℃ and 50% alkaline solution to get high quality chitosan was discussed. The results of these experiments not only solve the problem of environmental pollution but also provide basis for industrial productive of chitosan from waste mycelia.Part III. Studies on the modification and fluorescence properties of polymer chitosan.In this part, several different chitosan derivatives were synthesized, which were modified by schiff's reaction and O-acylation reaction through C2-NH2 and C6-CH2OH. The products were characterized by FT-IR and elemental analysis. These derivatives are soluble in some of the polar organic solvents such as DMSO, and exhibit strong blue-green fluorescence at the excitation of UV light. The fluorescence properties of chitosan derivatives whose molecular weight-average is about 104 are first studied. The fluorescence intensity of these chitosan derivatives increases and decreases with the different chromophoric group in the polymers' long-chain. The fluorescence properties of these chitosan derivatives are also changed with the different pH, solvent and concentration...