Effects of Sodium Dodecyl Sulfonate on the Sol-gel Transition of κ-Carrageenan
LI, Xiang a CHEN, Zhi-Yun b YIN, Yi-Mei *,a ZHANG, Hong-Bin a
(a Department of Polymer Science and Engineering, School of Chemistry and Chemical Technology, Shanghai Jiao Tong University, Shanghai 200240) (b School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237)
The effects of anionic surfactant sodium dodecyl sulfonate (SDSN) on the sol-gel transition of κ-carrageenan (κ-CAR), an anionic polysaccharide, have been investigated by different techniques including rheology, differential scanning calorimetry (DSC) and UV-Vis spectrometry. It has been found that, SDSN, at low concentrations (cSDSN＜5 mmol8226;L－1), slightly promoted the gelation of κ-CAR due to a weak salt-out effect, whereas at higher concentrations (c＞5 mmol8226;L－1), SDSN not only obviously decreased the sol-gel transition temperature of κ-CAR, but also formed a new ordered structure in the gel matrix of κ-CAR. The patterns of interactions between κ-CAR and SDSN were discussed. And a mechanism of cooperative interactions of electrostatic repulsion, competition for K＋and hydrophobic interaction has been proposed to interpret the experimental results.