Acta Phys. -Chim. Sin. ›› 1995, Vol. 11 ›› Issue (09): 785-790.doi: 10.3866/PKU.WHXB19950905

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Surface Activity of Dodecyltrialkylammonium Bromide and its Mixture with Sodium Dodecylsulfate

Zhao Guo-Xi,Xiao Jin-Xin   

  1. Department of Chemsitry,Peking University,Beijing 100871
  • Received:1994-09-29 Revised:1994-11-30 Published:1995-09-15
  • Contact: Zhao Guo-Xi

Abstract:

The surface activity of C12H25N(CnH2n+1)3Br and its mixture with C12H25OSO3Na has been studied by surface tension method. The composition of the surface adsorption layers, micelles and molecular interaction parameters have been calculated according to the regular solution theory. The effect of polar group size has been investigated emphatically. It shows that the polar group size exerts a remarkable effect on the single C12H25N(CnH2n+1)3Br systems─— with the increase of n, cmc’s decrease successively; and γcmc’s increase at first(n=1-2) and then decrease(n=2-4). This effect can be interpreted in terms of the steric hindrance, hydrophobic effect, HC-chain bending effect, and charge screening of the polar group moiety. In the mixthre of C12H25N(CnH2n+1)3Br and C12H25OSO3Na, the effect of polar size is less obvious.

Key words: Dodecyltrialkylammonium bromide, Polar group eddect, Cationic-nionic surfactants, Surface activity