Synthesis And Performances Of N,N-dimethyl-N-fatty Alcohol Polyoxyethylene Amine Oxide

Fatty alcohol polyethered amine oxide surfactants(Cm(EO)nAO) are defined as thesurfactants with a polyethenoxy ether segment((EO)n) between the hydrophobic tail(Cm) andthe hydrophilic head(AO). In order to investigate the structure-performance relationship of theCm(EO)nAO, five kinds of N, N-dimethyl-N-fatty alcohol polyoxyethylene amine oxideC12(EO)nAO(n=0,1,2,3,4) have been designed and synthesized. The molecular structure ofthe above amine oxide were confirmed by means of fourier transform infrared spectroscopy,nuclear magnetic resonance spectroscopy and electrospray mass spectrometry, respectively.Based on the surface active parameters, micelle aggregation numbers and interfacial dilationalviscoelasticity of the synthesized surfactants, the structure-performance relationship ofC12(EO)nAO were deduced. Moreover, in order to investigate the difference between theCm(EO)nAO and the structure-related alkyl dimethyl amine oxide(C12-14AO), C12-14(EO)3AOwas synthesized starting from commercial available fatty alcohol polyoxyethylene ethersulfate(AES). Some application properties of C12-14(EO)3AO, such as surface tention, salttolerance, hard water tolerance, lime soap dispersing power(LSDP), wettability andfoamability were mersured and compared with those of the C12-14AO.In the experimental research scope of this paper, the main research results are as follows:(1) The effect of the polyoxyethylene chain length on the suface properties ofC12(EO)nAO(n=0,1,2,3,4). It is found that along with the polyoxyethylene chainlength(n) increased from1to4, the cmc decreases, the γcmc, Aminand pC20increasesslightly, Гmand C20decreases, the cmc of C12AO is the biggest. The correlation betweenlogcmc and n by the method of drop volume and steady-state fluorescence is:logcmc==-3.519-0.080n(n=1,2,3,4) and logcmc=-3.396-0.106n(n=1,2,3,4),respectively.(2) The effect of the polyoxyethylene chain length on the micelle aggregation numbers ofC12(EO)nAO(n=0,1,2,3,4). It is found that along with the polyoxyethylene chainlength(n) increased from0to4, the correlation between aggregation numbers andconcentration is Nm=5.20c+30.97,Nm=26.94c+54.25, Nm=29.33c+46.01, Nm=30.65c+41.72and Nm=33.36c+35.39, respectively. Along with the n increased from1to4, the micelleaggregation numbers Nmand critical micelle aggregation numbers Nm,cdecreases and theNmand Nm,cof C12AO are the smallest. The correlation between Nm,cand n is:Nm,c=67.46-6.99n(n=1,2,3,4).(3) The effect of the polyoxyethylene chain length on the interfacial dilational viscoelasticityof C12(EO)nAO(n=0,1,2,3,4). It is found that along with the frequency increasing,dilational modulus and dilational elasticity increase, dilational viscosity decreases. Inaddition, with the increase of the concentration of C12(EO)nAO surfactants, dilationalelasticity and dilational viscosity increase to the maximum in the first phase and thendecrease, phase angle increases. Along with the polyoxyethylene chain length(n) increased from1to4, dilational elasticity decreases. The dilational elasticity of C12AO is thesmallest.(4) The properties comparation between C12-14(EO)3AO and C12-14AO. It is found that the cmcof C12-14(EO)3AO is6.03×10-5mol·L-1and γcmcis31.17mN·m-1, which is one order ofmagnitude smaller than that of C12-14AO; the salt tolerance and hard water tolerance areclose to each other, the salt tolerance of them is13.8%, hard water tolerance of them is5%. The foamability and wettability of C12-14(EO)3AO(148mm,40.1s) are superior toC12-14AO(138mm,77.9s), LSDP of C12-14(EO)3AO is6, which is superior to C12-14AOwhich is14.