In order to obtain a water-soluble gellan derivative, carboxymethyl-gellan was prepared. The carboxymethyl side group was introduced by adding the sodium monochloroacetic acid to gellan under alkaline conditions. The degree of substitution was determined by two different methods; potentiometric titration and infrared spectroscopy. A linear relationship was found between results from the two methods. It was found that the degree of substitution can be controlled by changing the reaction conditions. The solubility of gellan in water is found to increase by the carboxymethylation. The carboxymethyl gellan obtained here dissolved in water at concentrations up to 10% (wt/wt) at 25°C. It is was also found that the solution of the carboxymethyl-gellan does not form a gel when it was cooled to 0°C.
All Science Journal Classification (ASJC) codes
- Organic Chemistry
- Polymers and Plastics
- Materials Chemistry