Abstract:

In order to address the defect of poor water solubility of the non-ionic surfactant N, N-dimethyl-9-decenamide （NADA）, the possible synergistic effect between NADA and anionic surfactant sodium dodecyl sulfate （SDS） was investigated in the binary systems of NADA-SDS. The results show that positive synergistic effects are observed by blending NADA and SDS, leading to an obvious increasing in water solubility of NADA. At 25 ℃, the aqueous solutions of NADA-SDS （where the mass fraction of NADA is 1%） are transparent when the mole fraction of SDS （x_S） > 0.05. The efficiency of reducing surface tension is significantly improved by the formation of NADA-SDS hybrid micelles. The minimum critical micelle concentration （cmc, in terms of the total concentration of NADA-SDS） and the maximum critical micelle aggregation number （[N_m]） are obtained at the mole fraction of NADA （x_N） = 0.5 as 4.04 mmol/L and 76, respectively. The effectiveness of reducing surface tension of NADA-SDS is remarkably enhanced by the forming of NADA-SDS hybrid adsorption layer. The minimum surface tension at cmc （γ_cmc） of 28.44 mN/m is achieved at x_N = 0.9.

Key words: binary system, synergistic effect, N,N-dimethyl-9-enamide, sodium dodecyl sulfate, critical micellar aggregation number