Study On The Preparation, Reaction Kinetics And Properties Of Carboxymethyl Potato Starch

In this thesis, carboxymethyl potato starch was synthesized respectively in two different reaction media and the factors affecting the process of reactions were investigated systematically. Moreover, the kinetics of carboxymethylation on potato starch and solution properties of carboxymethyl starch aqueous solution were studied. In addition, ionic crosslinked chitosan-carboxymethyl starch gel beads were prepared and the drug release behaviors of drug-loaded beads were researched in simulation duodenal fluid. The main results were summarized as follows:(1) Carboxymethyl potato starch was synthesized in isopropanol solvent. The influences of etherification temperature, alkalization and etherification time, sodium hydroxide to monochloroacetic acid molar ratio, monochloroacetic acid to anhydroglucose units in starch molar ratio, the ratio of isopropyl alcohol volume to starch mass on degree of substitution and reaction efficiency of carboxymethyl starch were investigated. And the optimal reaction conditions for the carboxymethyl potato starch were obtained. Moreover, potato starch and carboxymethyl potato starch were characterized by Fourier transform infrared spectrophotometer and scanning electron microscope. In addition, the degree of substitution of carboxymethyl starch was determined by copper salt precipitation method.(2) Optimization of preparation conditions of carboxymethyl potato starch was carried out through orthogonal experimental design in the solvent of ethanol-water mixture. The effects of relevant factors on the apparent viscosity of 2% carboxymethyl starch aqueous solution and degree of substitution were investigated. These condition parameters included charging times of sodium hydroxide, mixing time of starch and solvent, etherification temperature, alkalization time, water content in the mixed solvent, ratio of liquid volume to starch mass, molar ratio of sodium hydroxide to monochloroacetic acid and molar ratio of monochloroacetic acid to anhydroglucose unit in starch. Furthermore, potato starch and carboxymethyl potato starch were characterized by Fourier transform infrared spectrophotometer. And the apparent viscosity of 2% carboxymethyl starch aqueous solution and degree of substitution were measured by the J acid colorimetric method and by NDJ-1 viscometer, respectively.(3) The kinetics of starch carboxymethylation in methanol, isopropanol and methanol-isopropanol mixtures was explored and carboxymethyl kinetic equation was established. The influence of carboxymethyl process on crystalline structure of potato starch was studied by X-ray diffractometer. And the glass transition temperatures of potato starch and carboxymethyl potato starch were determined using a sapphire differential scanning calorimeter.(4) The viscosity behaviors of CMS aqueous solution were researched. The dependences of apparent viscosity of CMS aqueous solution on concentration of CMS aqueous solution, stirring time, glycerin, glucose, konjac glucomannan, seven low molecular weight electrolytes, dissolving sequence and temperature, and shear rate were investigated. The results showed that these factors had very different effect on apparent viscosity of CMS aqueous solution.(5) Chitosan-carboxymethyl starch gel beads (CSCM) were prepared using sodium tripolyphosphate as an ionic crosslinker. And swelling experiments were performed by immersed about 50 mg dried CSCM in 50 ml buffer solutions with different pH values at 37±1℃. Moreover, in vitro release of model drug from these beads obtained under different reaction conditions was studied in simulation duodenal fluid. In addition, the interaction between drug (or polymer) and polymer was characterized by Fourier transform infrared spectrophotometer.