Preparation, Characterization and Swelling Studies of Carboxymethyl Sago Starch Hydrogel

Abstract Carboxymethyl sago starch (CMSS) hydrogel was prepared by dissolving CMSS in HCl solution under vigorous stirring to form gel. The parameter studied were the effect of the percentage of CMSS, concentration of the acid solution, reaction time and reaction temperature to identify the optimum condition of preparation of CMSS hydrogel. 60% of CMSS in 2.0M acid solution for 12 hours reaction time at room temperature were the optimum conditions for CMSS hydrogel. The hydrogel was characterized by using Fourier Transform Infrared (FT-IR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). FTIR spectrum of CMSS shows an additional absorption band at 1597 cm-1 indicating the substitution of CH2COO-Na+ group on the starch molecular chain during carboxymethylation, while the spectrum of CMSS hydrogel shows an additional sharp absorption band at 1723 cm-1 indicating that the Na in CMSS being exchanged to H from hydrochloric acid solution. SEM image of CMSS hydrogel shows pores in structure and connected to each other to form networks. TGA curve shows that the maximum rate of thermal decomposition of CMSS hydrogel is higher than CMSS at 330.22 ºC with 60.22% major weight loss. This could be due to the presence of the cross-linkages in the CMSS hydrogel. CMSS hydrogel gives high swelling degree in PBS solution at pH 7 and low swelling degree in acidic medium.