| Low-molecular-weight gel are formed by weak non-covalent interactions between molecules.Due to the reversibility of non-covalent interaction forces and the controllability of self-assembly process,low-molecular-weight gel are used as an intelligent soft material.The low molecular weight gel with different stimuli-responsive properties possess different characteristics,broadening the application range of low-molecular-weight gel,and thus the stimuli response has gradually become a hot spot for the design and synthesis of low-molecular-weight gelator.In this study,low-molecular-weight gelator based on stigmasterol-ferrocene was prepared,and the gel with properties of with heat,ultrasound,and thixotropy could be formed by heating-cooling cycle.The SGF/cyclohexane gel of redox and alcohol multiple stimuli response can be used for the preparation of oxidation-sensitive materials and have application potential in sensors and specific recognition.The main research content is as follows:(1)Preparation and characterization of a novel sti gmasterol-ferrocene deri vative: Using stigmasterol and ferrocenecarboxylic acid as raw materials,stig masterol-ferroferric acid ester(SF)?stigmasterol-ethylenediamine-ferroceneamide(SXF)and stigmasterolylglycine ferroceneamide(SGF)was synthesized.Its st ructure was confirmed by mass spectrometry,nuclear magnetic resonance spec troscopy and nuclear magnetic resonance spectroscopy.(2)Study on the Gel Properties of low-molecular-weight gel: The gelation behavior of three stigmasterol-ferrocene derivatives was tested in 33 organic solvents.It was found that only SGF can form gels in cyclohexane and ethyl acetate by self-assemble.Concentration and phase transition temperature experiments were performed on the gelation ability and gel strength of SGF in cyclohexane and ethyl acetate.(3)Study on the driving force of low-molecular-weight gel: The infrared spectra of the SGF xerogel and non-gelled SGF powders were measured.The results showed that after the gel was formed,the characteristic peak of NH in the SGF molecules shifted to low wave numbers,indicating that intermolecular hydrogen exists between the SGF molecules in the gel.The water contact angle of the SGF/cyclohexane(ethyl acetate)solution and xerogel was tested.The results showed that the water contact angle of the SGF became larger after the gel formation,and the hydrophobic force on the surface of the molecule was enhanced.Hydrogen bonding forces exist between the SGF molecules in the gel.(4)The morphology of low-molecular-weight gel: The morphology of the SGF gel was determined by scanning electron microscopy.It was found that there was no significant difference in the morphology of the SGF/ethyl acetate gel formed under different conditions.When the concentration of SGF/cyclohexane gel is greater than 25 mg/m L,the dry gel morphology changes from a fibrous sheet structure to a regular porous spherical structure with a diameter of about 3 ?m.The XRD results of the SGF/ethyl acetate gel show that the interior is a layered stack,and t he simulation of the stacking model has been completed by a computer.(5)Stimulation responsiveness of SGF/cyclohexane gel: SGF gels have thermal,ultrasonic,mechanical stress,redox,and alcohol solvent stimuli response characteristics.SGF/cyclohexane gels have reversible redox stimuli responsiveness and the nanofiber structure of SGF/cyclohexane gels can be regulated by redox.At the same time,SGF/cyclohexane gels were dissociated under the stimulation of normal monohydric alcohols with different carbon chain lengths(C1-C10),and methanol could be specifically recognized in various alcohol solvents.Infrared spectroscopy showed that the stimuli response was that the introduction of methanol destroys the intermolecular hydrogen bonds of SGF,destroys the driving force for gel formation,and eventually leads to the disintegration of SGF/cyclohexane gels. |
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