Effect of Temperatures on Modification of Alginate Hydrophobicity using Dodecenyl Succinic Anhydride

Abstract

Alginate is a highly hydrophilic polysaccharide as it contains several hydroxyl groups in the main backbone chain. Some applications for example as surfactants, however, require alginate to have higher hydrophobic properties. Hence, attempts are conducted to improve its hydrophobicity. Dodecenyl succinic anhydride (DSA) has a long hydrophobic chain that could substitute the hydroxyl groups of alginate and improve its hydrophobic properties. This study aimed to produce modified alginates with higher hydrophobicity using DSA as a modifier. The alginate modification was conducted at 30-70oC. The result showed that the degree of substitution (DS) increased in short time and low temperature of reaction. The highest DS value (0.1515) was obtained at 30oC for 30 min which gave the highest viscosity (14.74 cps) and the lowest surface tension (94.08 mN/m). The viscosity and surface tension values for the native alginate were 9.53 cps and 162,98 mN/m, respectively. Meanwhile, the viscosity and surface tension of the lowest DS (0.083) were 11.06 cps and 119.63 mN/m, respectively. The attachment of the dodecenyl succinic group was confirmed by the IR spectra as the presence of ester groups in the modified alginate.