Preparation Of Dual Stimulus Responsive Emulsion Based On Ferrocenyl And Tertiary Amin

Stimuli-responsive surfactants refer to the surfactant whose structure or property can change reversibly under certain external stimulus conditions,mainly including pH,redox,temperature,CO2/N2,magnetic and other stimulus response surfactants.At present,most of the researches focus on single stimulus response and few on multiple stimulus response.Compared with the single stimulus response surfactant which can only be adjusted by a single means,the multiple response surfactant can be selected by more means,which can not only expand the application range of surfactant,but also improve the control accuracy of the system.Therefore,the multiple stimuli-responsive system has a better application prospect.In this paper,FA-DMDA-Ox,a surfactant with dual stimulus response,is synthesized by oxidation through simple electrostatic interaction between ferrocenecarboxylic acid(FA)and N,N-Dimethyldodecylamine(DMDA),and its structure was characterized.The ultraviolet absorption spectrum and surface tension before and after oxidation are measured to demonstrate the redox response.Optical transmittance and surface tension of FA-DMDA-Ox under different pH are tested to prove its pH response.A series of oil-in-water emulsions with different concentrations are prepared at 25℃ using FA-DMDA-Ox as the surfactant and paraffin as the oil phase.The concentration of the surfactant is determined by measuring the water fraction and interfacial tension of the emulsion.Bytesting stand for 2 weeks,the appearance of the emulsion,the stability is determined by the size and Zeta potential.Through the emulsion in the loop to join Na2SO3 and H2O2 to detect the redox response performance.Through the reaction in the process of monitoring to the state of emulsion appearance,particle size as well as the interfacial tension and so on data proved that the emulsion with a redox response.The pH response was measured by adding HCl and NaOH to the emulsion.The pH response of the emulsion is also proved by the appearance,particle size and interfacial tension of the emulsion.Finally,the emulsion demulsification mechanism constructed by FA-DMDA-Ox is analyzed by the redox and pH performance data of FA-DMDA-Ox.Secondly,in order to investigate the influence of surfactant carbon chain length,the tertiary amine with carbon chain of 10,14,16 was selected to react with ferrocitric acid,and three kinds of double-stimulus response surfactants FA-DMA-Ox,FA-DMTA-Ox and FADMHA-Ox are prepared.Firstly,the surface tension of different surfactants is tested to detect their surface activity.These four different surfactants are then emulsified with paraffin to form an emulsion.The stability of the 2 weeks standing emulsion is analyzed by detecting its appearance,particle size and Zeta potential,and then the surfactant fA-DMHA-Ox with carbon chain length of 16 is determined to be the most stable.The redox reaction properties of the four surfactants are consistent.The pH response performance of different surfactants is evaluated by pH response experiments.Finally,the Pickering emulsion of liquid paraffin is prepared by mixing fa-dmda-ox with nano-silica particles to achieve in situ hydrophobicity of silica surface.The oil phase was replaced with n-octane and toluene to obtain a stable Pickering emulsion.Through the redox response and pH response test of Pickering emulsion,it is confirmed that the oil phase of demulsification contains no surfactant.The adsorption of FA-DMDA-Ox on the silica surface was predicted by analyzing the Zeta and contact angle of nano-silica particles dispersed in different states and concentrations of FA-DMDA-Ox.By detecting the surface tension before and after adding 0.5 wt%nano-silica particles into FA-DMDA-Ox in different states and the adsorption capacity of FA-DMDA-Ox on nano-silica/water interface before and after reduction,the adsorption performance of silica surface is proved.The response mechanism of Pickering emulsion constructed by FA-DMDA-Ox and nano-silica particles is analyzed by the adsorption of silica under different conditions.