Study On Dual Stimuli-Responsive Wormlike Micelles Systems

Stimuli-responsive wormlike micelles（SWLMs）is a special kind of wormlike micelles,which can dynamically ‘‘adapt’’ their properties,function,or appearance in response to external environmental stimuli.Compared with the traditional WLMs,this type of WLMs has advantages such as adjustable,reversible and controllable,attracting more and more people’s attention.However,most of SWLMs were designed to respond to a single stimuli,and there are only few reports on multiple SWLMs.Therefore,We developed a series of double stimuli-response WLMs based on stimuli-response surfactants and adjuvants.Their rheological properties and stimuli-response properties were systematically investigated through,conductivity meter,rheology,surface tension,1H NMR,DLS and Cyro-TEM.The main results are summarized as follows:1 The building of double stimuli-responsive WLMs based on stimuli-response surfactant（1）The azobenzene-containing cationic surfactants（4-butylphenyl）-2-（4-trimethylammoniumhexyloxyphenyl）diazene（C₄AzoC₆N）was synthesized firstly.Then,the chemical structure and purity of final product was identified by 1H NMR and mass spectrometry;The light-response property were identified by 1H NMR and UV absorbsion and the conversion of cis-trans isomerization in aqueous solution can reach 85%;It is found that C4 Azo C6N has a good ability to reduce the surface tension through the surface tension measurement.（2）C₄AzoC₆ N can be used to prepare CO₂/N₂-light double stimuli-responsive WLMs with two different kind of organic salts,sodium dodecylaminopropionate(C₁₂NC₂COONa)and sodium azophenolate sodium（AzoONa）.AzoONa has a stronger enhancement for the formation of WLMs,and the viscosity of C4 Azo C6N-AzoONa system can reach 230 Pa?s.（3）Due to the light-sensitive of C4 Azo C6N,both binary systems have good light-response property,and shows a transition between a high viscosity with wormlike micelle and a low viscosity with spherical micelles by UV light and blue light irradiation.The light-response property of binary systems is reversible,and the vicosity can still return back to exactly its original value without any deviation after three cycles.（4）Due to the pH-sensitive of C₁₂NC₂ COONa and AzoONa,both binary systems have good CO₂-response property.Afre bubbling CO₂,the WLMs were destroyed and the viscosity of solution decreased.After heating and bubbling N₂,the viscosity of solution can return back to its original value.The viscosity of system can be converted between high viscosity and low viscosity by bubbling CO₂ and N₂ repeattly.2 The building of stimuli-responsive WLMs based on conventional surfactants（1）By adding CDA to a typical binary WLMs system of CTAB and CA,we prepared CO₂/N₂-light double stimuli-responsive WLMs（CTAB-CA-CDA-CO₂）.After adding CDA,the viscosity of ternary system greatly increased and reach 537 Pa?s,which is five times that of binary system.CDA can occur protonation and deprotonation reaction by bubbling CO₂ and N₂,leading to the formation and destruction of WLMs in the system.Therefore,the system has a good CO₂-response property and reversibility.Due to the light-sensitive of CA,after UV light irradiation,trans-CA can be converted to cis-CA,resulting the destruction of WLMs,but this transition is irreversible.（2）We prepared CO₂/N₂-redox double stimuli-responsive WLMs（CTAB-FA-CDA-CO₂）by mixing CTAB、FA and CDA.Although the molecular structure of FA is similar to CA,the CTAB-FA-CDA-CO₂ system had a lower viscosity of only 23 Pa?s compared to the CTAB-CA-CDA-CO₂ system.Due to the presence of CDA,the CTAB-FA-CDA-CO₂ system also has good CO₂/N₂ reversibility.At the same time,because of the presence of FA,the system also has redox reversibility.However,in the process of adding the oxidant and the reducing agent,non-removable impurities were introduced into the system.Thus,the viscosity of system will be reduced after repeating three times.