Effect of Tetramethyl Ammonium Bromide or Surfactants with Different Chain Length on Sol-Gel Transition of Methylcellulose-Ortho-Methoxycinnamic Acid Solution

The sol-gel transitions of methylcellulose(MC)-ortho-methoxycinnamic acid sodium(OMC-) solution in the presence of tetramethyl ammonium bromide，dodecyl ammonium bromide (DTAB), tetradecyl trimethyl ammonium bromide (TTAB) and cetyl trimethyl ammonium bromide (CTAB) were studied. Results showed that the sol-gel transition temperature of MC-OMC-solution unchanged with the mass fraction of DTAB, TTAB and CTAB. However, when tetramethyl ammonium bromide was added to MC-OMC- solution, the sol-gel transition temperature of the solution decreased significantly. In MC-OMC- solution containing tetramethyl ammonium bromide or different chain length surfactants, surfactants such as TTAB tended to form free hemispherical micelles. Strong electrostatic interaction between OMC- and tetramethyl ammonium bromide would destroy the core-shell structure formed by MC and OMC-.