Study On The Synthesis And Compounding Properties Of N,N-dimethyl-9-decenamide

In practical applications,surfactants often appear in the form of a combination of multiple surfactants.It is because most surfactants can be mixed to obtain more excellent surface chemical properties.Nowadays,the performance of surfactants can not only be required to meet people’s needs,but also meet the requirements of eco-friendliness.N,N-Dimethyl-9-decenamide（NADA）is a green non-ionic surfactant that does not contain common hydrophilic groups.However,its poor water solubility has made its practical application to be greatly restricted.So,there are few studies and reports on NADA.In order to improve the poor water solubility,temperature sensitivity,and poor emulsification ability of NADA when it used alone and unleash its superior surface chemical properties and excellent solvent properties to broaden the scope of the application of NADA.NADA was synthesized by us,and mixed with the anionic surfactant sodium dodecyl sulfate（SDS）,the cationic surfactant dodecyltrimethylammonium bromide（DTAB）,the non-ionic surfactant dodecyl polyoxyethylene ether（AEO₉）and zwitterionic surfactant dodecyl sulfobetaine(SB₁₂)respectively.Four different binary systems’properties of surface chemistry and the synergistic effects were researched systematically.The basic application performance of NADA-SDS,NADA-DTAB and NADA-AEO₉binary systems were tested.For its relatively good synergistic effect,NADA-SDS binary system was selected to mixed with oil（n-hexane）and water to explore whether any aggregates with application potential（such as microemulsion,liquid crystal or gel）can be formed by NADA-SDS/hexane/water system.Within the category of this article,the main research contents and conclusions were summarized as follows:（1）Synthesis,characterization and basic properties of NADANADA was synthesized with 9-decenol（NDE）as raw material.Molecular structure of NADA was characterized by four methods:total reflection Fourier infrared spectroscopy（FTIR）,proton nuclear magnetic resonance spectroscopy（¹H NMR）,carbon nuclear magnetic resonance spectroscopy(¹³C NMR),and electrospray mass spectrometry（ESI-MS）.The normalized purity of NADA tested by gas chromatography was higher than 98%.The basic parameters of NADA were determined such as the water（oil）solubility,surface tension,and oil（petroleum ether）-water interfacial tension.The results showed that the cloud point（C_P）of NADA is lower than 0℃.So the solubility of NADA in water is poor at25℃.NADA can be miscible with many organic solvents.The surface tension at the critical micelle concentration(γ_cmc)of NADA is about 28.85 m N/m.But the ability to reduce the oil（petroleum ether）-water interfacial tension of NADA is poor.The interfacial tension（IFT）is higher than 19 m N/m.（2）Synergistic effects of NADA-SDS,NADA-DTAB,NADA-AEO₉and NADA-SB₁₂binary systemsIn the NADA-SDS binary system,positive synergistic effects were observed by blending NADA and SDS,leading to an obvious increasing at C_Pof NADA and solubility of NADA-SDS in water.The efficiency of reducing surface tension was significantly improved by the formation of NADA-SDS hybrid micelles.The minimum critical micelle concentration（cmc）and the maximum critical micelle aggregation number（[N_m]）were 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 was remarkably enhanced by the forming of NADA-SDS hybrid adsorption layer.The minimum surface tension at cmc(γ_cmc)of 28.44m N/m was achieved at x _N=0.9.In the NADA-DTAB binary system,positive synergistic effects were observed by blending NADA and DTAB,leading to an obvious increasing at C_Pof NADA and solubility of NADA-DTAB in water.The effectiveness of reducing surface tension of NADA-DTAB was remarkably enhanced by the forming of NADA-DTAB hybrid adsorption layer.The minimumγ_cmcof 28.44 m N/m was achieved at x _N=0.9.However,we found there was only a weak interaction produced by NADA-DTAB binary system in the mixed micelles,which cannot effectively improve the efficiency of reducing the surface tension and can not make the micellar structure more compact.In the NADA-AEO₉binary system,positive synergistic effects were also observed by blending NADA and AEO₉,leading to an obvious increasing in water solubility of NADA.The efficiency of reducing surface tension was significantly improved by the formation of NADA-AEO₉hybrid micelles.The effectiveness of reducing surface tension of NADA-AEO₉was remarkably enhanced by the forming of NADA-AEO₉hybrid adsorption layer.The minimum cmc and the minimumγ_cmcwere obtained at the mole fraction of NADA（x _N）=0.1as 4.64×10^-2mmol/L and 30.04 m N/m,respectively.In the NADA-SB₁₂binary system,neither the C_Pof NADA nor the solubility of NADA in water can be increased by the compounding of NADA and SB₁₂.Any interaction did not produced by NADA-SB₁₂binary system in the mixed micelles.Only when x _N>0.2,a weak interaction in the mixed adsorption layer occurred in the NADA-SB₁₂binary system.（3）Basic application properties of NADA-SDS,NADA-DTAB and NADA-AEO₉binary systemsThe basic properties of NADA-SDS,NADA-DTAB and NADA-AEO₉binary systems were investigated from four aspects:emulsification property,foam property,wetting property and solubilization ability.The results showed that NADA compounded with SDS,DTAB and AEO₉can get better emulsification performance than NADA.The emulsion formed by them with uniform particle size and remained stable after standing for a week.Three binary systems all show good foam performance.The foaming performance of each binary system is higher than that of single surfactant.Foam system with different stability can be obtained by adjusting x _N.The three binary systems also showed much higher wetting performance than NADA.NADA-SDS,NADA-DTAB and NADA-AEO₉binary system,the better wetting performance than single AEO₉only appeared at x _N=0.1.The excellent solubilization ability to n-hexane was showed in all three binary systems.The solubilizing ability of NADA-SDS,NADA-DTAB and NADA-AEO₉binary system to hexane can reach 1.61,1.59 and 7.80L/mol respectively.（4）NADA-SDS/n-hexane/water system microemulsionFor its good synergistic effect and basic application performance,NADA-SDS（x _N=0.9）binary system was selected to mix with oil（n-hexane）and water to explore the aggregates formed by them.The results showed that three aggregates of microemulsion,liquid crystal and gel under different water content（water to total mass ratioφ_w）can be formed by the NADA-SDS/n-hexane/water system.A pseudo ternary phase diagramand was drawn to divide each aggregate area.A transparent W/O type microemulsion formed at lowφ_wwas determined through the conductivity method and dynamic light scattering（DLS）,and the area of the microemulsion area can reach 0.48.As theφ_wincreased,lower viscosity and optical anisotropy was exhibited.This structure with optical anisotropy was determined as lamellar liquid crystal by Polarization microscopy（POM）,nuclear magnetic resonance deuterium spectroscopy（²H NMR）and small-angle X-ray scattering（SAXS）tests.With the further increase ofφ_w,the turbidity of the system gradually disappeared.And then a higher viscosity was produced.The rheological test confirmed that gel structure was formed in the NADA-SDS/n-hexane/water system.Asφ_wincreased,the apparent viscosity of the gel will gradually increase to 750 Pa·S.In the NADA-SDS/n-hexane/water system,the change of water content triggered the conversion of microemulsion-liquid crystal-gel.