Studies On Preparation, Properties And Applications Of Carboxymethyl Chitosan And Its Derivatives

Chitosan, the deacetylated derivative of chitin, is one of the abundant renewable, nontoxic and biodegradable carbohydrate polymers. It has received much attention in many fields due to the distinct physiologic activities and potential functions. But the application of chitosan was limited duo to its low-water-solubility. People have been interested in getting water-soluble derivatives of chitosan by many kinds of chemical modification, of which carboxymethylation is the most common and effective way. Carboxymethyl chitosan has many properties, such as improving density, good decentralization and emulsification, excellent retention-moisture, easily-formed film and hydrogel and so on Because of these properties, carboxymethyl chitosan has been applied in many fields.In this paper, molecular structure design, characterization of carboxymethyl chitosan was studied. Application of carboxymethyl chitosan on medical dressing, preservation fruits was researched.The main contents and conclusions are as follows:1. N,O-carboxymethyl chitosan/gelatin blend films were successfully prepared by solution method and characterized by FT-IR X-RD SEM and optical transmittance. The results indicated there was some strong interaction and good compatibility between N,O~carboxymethyl chitosan and gelatin molecular in the blend films. According to the measurements of mechanical properties, when the content of N,O-carboxymethyl chitosan was 20 weight%, the tensile strengths(db ) in dry state of the blend film was enhanced by 67.7%and 74%, compared to the N,O-carboxymethyl chitosan film and the gelatin film respectively. With the add of 2-hydroxy3-trimethylammoniumpropyl chitosan , the antibacterial characteristics of the blend films were improved evidently.2. O-carboxymethyl chitosan complex fresh-keeping agents to strawberry storage were selected out by orthogonal test. The optimal prescription was 1% O-carboxymethyl chitosan, 0.01% tea polyphenol and 0.2% potassium sorbate. The effects of different treatments on physiological and physical changes were watched and measured. It was shown that coated with the edible films was significantly effective on decreasing the loss of fruit nutrition,weight loss rate, and inhibiting respiration.3. A series of water-soluble amphoteric chitosan derivatives (QCMCT) were prepared by quaternary ammonium cationization of carboxymethyl chitosan (CMCT) in aqueous sodium hyoxide by using 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPAC) as the cationic monomer in water and characterized by FT-IR. The properties of the quatemized CMCT with different degrees of substitution of quaternary amrnonium(DSQ) and molecular weights were investigated. The results showed that these water-soluble amphoteric chitosan derivatives had a good ability of moisture-absorption and moisture-retention and the degrees of substitution of quaternary ammonium and molecular weights had an effect on it.