Synthesis And Characterization Of Photoresponse Ionic Liquid Surfactants

Starting from the development of green chemical concept,new environmental multifunctional surfactants with its unique physical and chemical properties attracts the attentions of the researchers all over the world.Embedded in the hydrophobic chain of surfactants photosensitive groups,in hydrophilic group of ionic liquid modified at the same time,the synthesis of photosensitive type ionic liquid surfactant not only has the general surface activity,but also has the special optical activity and solubility in water.In this paper,the first product: 4-Butylazobenzene-4'-?oxyethyl?methylimidazolium bromide?AZMIMBr?was synthesized from 4-butylaniline,phenol,1,2-ethylbromide and 1-methylimidazole by the methods of diazo coupling,Williamson ether-forming reaction and substitution reaction,then the second product: 4-Butylazobenzene-4'-?oxyethyl?methylimidazolium tetrafluoroborate?AZMIMBF4?was synthesized through AZMIMBr reaction with AgBF4 by the methods of ion exchange method.Experiments further studied the system of cationic surfactant dodecyl hydroxyethyl dimethyl ammonium bromide(C₁₂HDAB)mixed with AZMIMBr micellar process,and made a research on the ultraviolet light under the different ratio of the influence of the optical properties of micellar system.The structure of AZMIMBr and AZMIMBF4 was characterized by means of 1H NMR;thermal analysis indicates the better thermodynamic stability.At 20 45 ? temperature range,through measuring their conductivity curve along with the change of solution concentration in aqueous solution,we got the critical micelle concentration?CMC?under different temperature,and the surface tension of the drop volume method is used to determine the CMC values got by conductivity were similar at 25 ?,the two supporting each other.Experiments show that the CMC values of two surfactants were 2.20 mM and 1.14 mM respectively at 25 ?,because the CMC is mainly related to the molecular structure of the surfactant,the CMC of AZMIMBr is greater than the CMC of AZMIMBF4.In the same large nonpolar groups and imidazole cation group,the differences in CMC values are the role of Br-and BF4-ions,the polarity of Brin the sample AZMIMBr is bigger,stronger hydrophilicity,weakened the repulsion between the hydrophobic group and solvent,and the sample AZMIMBF4 has small polarity hydrophobic effect,more conducive to the formation of micelles.The CMC increases with the increase of temperature,? decreases with temperature rise,it related to counter ion hydration radius and polarity.The experiment also measured the AZMIMBF4 Krafft point?40 ??to determine the best solution temperature.There photo-responsive characteristics were analyzed by full wavelength scanning,and the photoisomerization occurred under the irradiation of ultraviolet light at 365 nm.The CMC values obtained by conductivity and Surface tension method Experiments have established that the surfactant from stable trans structure into unstable behavior of cis structure change under UV irradiation.And the needed time to reach steady-state level under the UV irradiation and different time of the reversal rate were concluded through UV absorption spectra,nuclear magnetic resonance instrument.And their lyotropic liquid crystal and micelles microstructure transitions were testified by POM observations and SAXS analysis.The results indicate that AZMIMBr and AZMIMBF4 possess good photo-responsive characteristics.In addition,C₁₂ HDAB and light have been selected to study the influence on the aggregation behavior of the mixture system AZMIMBr/C₁₂ HDAB.By using surface tension and conductivity measurement,CMC values of the different mole ratio solution greatly reduced when the mole ratio decreased,but located between the two,and tend to CMC of AZMIMBr.Micellization process of the mixture system was analyzed;it can be found that the variation trend of the micellization process with the thermodynamic parameters was mostly similar to the single surfactant.Meanwhile,the microstructure change of the mixture system has been investigated by using UV absorption spectra,polarizing microscope,dynamic light scattering technology and so on,it provides the experimental basis and theoretical guidance for the application of photosensitive surfactant in nanometer material,biological medicine and other fields.