Building Of Stimuli-Responsive Low Molecular Organic Gel

Recently,the organogels formed by low molecular compounds have received great attention.Low molecular organic gel（LMOG）is a kind of self-assemble system which constructed three-dimensional net structure by noncovalent interaction.The structures of gelator have great effects on the performance of the gel and its stimulate response.Therefore,some stimuli-responsive greatly improved the function of gel,and made gel responsive to outside stimulate,such as light,electricity,ph,temperature,sound,which made it become a new smart materials and have extensive application prospect in areas such as sensors,drug delivery.Based on it,we choosed stimuli-responsive groups,such as selenium,primary amine,styrene,ferrocene and azobenzene.Then we introduced them in the structure of gelators and built a series of stimuli-responsive low molecular organogel.The common characters and stimuli-responsive performance were explored by the means of scanning electron microscope（SEM）,polarizing microscope（POM）,thermal analysis system,¹H NMR and so on.The main results are summarized as follows:1 Synthesis and application of a new type of oxidation reduction gelator:A new type of oxidation reduction gelator（Chol-Se）was synthesized.The construture and purity of Chol-Se have been proved by mass spectrometry（MS）and ¹H NMR.Chol-Se could form gel in a variety of solvents.The microstructures of the gels have been studied and compared with each other by SEM and POM.We calculated the thermodynamic parameters and found that the process of gelation was a spontaneous process.The accumulation model of Chol-Se in ethyl acetate has been gained by combining the XRD results of Chol-Se/ethyl acetate and the calculated molecular structure of Chol-Se gained by Gaussian 09.The molecular structures of Chol-Se before and after oxidization have been charactered by MS and ¹H NMR.The switchable performances of the gel formed by Chol-Se have been tested.The morphologies of the gel before and after oxidization have been observed by SEM and POM.2 The building of UV-stimuli-responsive LMOGs based on octadecylamine(NC₁₈)and4,4’-Stilbenedicarboxylic acid（St）:A new UV-stimuli-responsive LMOG has been built by conventional reagents octadecylamine(NC₁₈)and 4,4’-Stilbenedicarboxylic acid（St）.The gelator NC₁₈-St could formed gel in several solvents.The basic performances were tested by SEM,POM,DSC,XRD.The accumulation model of NC₁₈-St in toluene has been gained by combining the XRD results of NC₁₈-St/toluene,the calculated molecular structure of NC₁₈ and St and the ¹H NMR of NC₁₈,St and NC₁₈-St.We guess that hydrophilic group of NC₁₈-St formed ion pair and then constructed self-assemble aggregates.The gels formed by NC₁₈-St in methanol,ethanol and toluene could be destroyed by UV irradiation and can’t reform after blue light irradiation.The morphologies of the gel before and after UV irradiation have been observed by SEM and POM.3 The building of CO₂-redox double stimuli-responsive LMOGs based on octadecylamine(NC₁₈)and ferrocenemethanol（FcOH）:In order to construct the CO₂-redox double stimuli-responsive low molecular organogel system,we choose conventional reagents octadecylamine(NC₁₈)and ferrocenemethanol（FcOH）to mix.The gelator NC₁₈-FcOH could formed gel in cyclohexane after bubbling CO₂.The gelators formed long fibers accumuled by flaky aggregates in cyclohexane.The accumulation model of NC₁₈-FcOH-CO₂ in cyclohexane has been gained by combining the XRD results of NC₁₈-FcOH-CO₂/cyclohexane,the calculated molecular structure of NC₁₈and FcOH and the ¹H NMR of FcOH and NC₁₈-FcOH-CO₂.The gels formed by NC₁₈-FcOH-CO₂ in cyclohexane is a kind of CO₂-redox double stimuli-responsive low molecular organogel system.The process of CO₂/heating swiching could repeat over five times.The gel could also be destroyed by addition of oxidizing agent,but couldn’t reformed by adding reducing agent.The morphologies of the gel before and after destruction have been observed by SEM and POM.4 The building of CO₂-UV double stimuli-responsive LMOGs based on octadecylamine(NC₁₈)and azobenzene derivatives（AzoOH and AzoC2OH）:We construted two kinds of stimuli-responsive low molecular organogel systems:NC₁₈-AzoOH-CO₂/methyl alcohol and NC₁₈-AzoC2OH-CO₂/methyl alcohol by introducing two azobenzene derivatives:AzoOH and AzoC₂OH for mixing with octadecylamine(NC₁₈).NC₁₈-AzoOH-CO₂/methyl alcohol is different with common azobenzene derivatives systems,it just could destroyed by heating,and can’t destroyed by UV irradiation.But NC₁₈-AzoC2OH-CO₂/methyl alcohol not only could be destroyed by heating,but also UV irradiation.And it could reformed by blue light irradiation.We speculated the accumuled model and single/multiple switchable mechanism of the two systems by SEM,POM,XRD and ¹H NMR.