The interactions between gelatin and cetyltrimethyl ammonium bromide (CTAB) have been studied by the methods of conductivity, fluorescence and pH. The results indicate that with adding of gelatin the values of cac₁, cac₂, cmc increase and the micelle aggregation number reduces in the CTAB/gelatin/H₂O system. The freeze fracture transmission electron microscopy experiment shows that the complex forms between CTAB and gelatin molecules, and the structure of the complex changes from linear, curl, bead necklace, then rod like, finally to netlike structure sequentially with increasing the concentration of CTAB.

Key words: gelatin, CTAB, molar conductivity, fluorescence, FFTEM