Construction Of Poly (Ionic Liquid) Hydrogel And Phase-transfer System Based On Host-guest Interactions And Study On Their Mechanism

The major object of supramolecular chemistry research was studied on the specific structural aggregates resulted from intermolecular non-covalent bonding,which host-guest chemistry plays an important part.Cyclodextrin and cucurbituril are two representative host molecules,which are widely concerned by scientists because of their unique properties.Cyclodextrin is a series of specific structure,formed by a number of glucose units which linked through 1-4 glycosidic bond.The cyclodextrin molecules with different structures were named according to the number of different glucose units.The most famous cyclodextrin molecules are a-,?-and y-cyclodextrin and the corresponding number of glucose units are 6,7,and 8,respectively.The cyclodextrin host molecule is hydrophilic due to its hydroxyl structure,the cavity of the molecule is hydrophobic and the size of it becomes larger as the amount of glucose units increases.The hydrophobicity of the inner cavity and the characteristic of a specific cavity size enable the cyclodextrin host molecule to be complexed with the guest molecule under certain circumstances.For example,in aqueous solution,the cavity of the ?-cyclodextrin molecule could connected with the azobenzene group through hydrophobic interaction and size matching.The complex can be de-assembled-assembled by the cavity detachment caused by the conformational transformation of the azobenzene group under UV light.The cucurbit[8]uril(CB[8])has a large cavity,even can simultaneously bind two guest molecules,thus has a wider application scenarios.In recent years,design and preparation stable complexes using cucurbit[8]uril as host molecule attracted lots of attention.Cucurbit[8]uril has become another important research object in host-guest chemistry.Stimulus-responsive polymers are able to recognize certain specific external changes and produce responses such as light,heat,salt,and pH,magnetic fields and so on.In some specific cases,the responsive polymer system may even undergo a phase change.These properties provided a broad range of applications for stimuli-responsive polymers,such as the transport and selective release of drugs and the preparation of smart response materials.Non-covalent interactions were used to construct stimuli response systems,due to its specific reversibility.We introduced host-guest interaction into the field of poly ionic liquids,endow the PILs systems with stimuli-responsiveness through the action of non-covalent interactions.The main contents of the thesis include the following aspects:1.Functional compounds with different structures and ionic liquid monomers were prepared,including:6-bromohexyl-4-azophenyl ether(AzoC6Br),1-vinyl-3-[6-(4-azobenzene)hexyl]imidazolium bromide(VImAzo),1-vinyl-3-benzylimidazolium bromide(VImBn),?-cyclodextrin dimer(?-CD dimer),a-cyclodextrin dimer(a-CD dimer)and cucurbit[8](CB[8]),their structures and purity were determined by 1H NMR,13C NMR and FT-IR.2.Polyvinylimidazole was prepared by radical polymerization,the introduction of a permanent positive charge by quaternization with benzyl bromide and bromine-containing azobenzene derivative of the polyvinylimidazole yields poly(ionic liquid)s.The multi-stimuli responsive gel material was obtained by host-guest interactions,its photosensitivity and temperature sensitivity were verified by FT-IR and UV-Vis spectroscopy.It's fully approved the construction of polymers by 1H NMR,13C NMR and FT-IR analysis.The photosensitivity and temperature sensitivity of the gel were also verified by rheological tests.2D NOESY test demonstrated the existence of host-guest interactions.The result show that the intensity of hydrogel system based on poly(ionic liquid)s and dual supramolecular interactions can be significantly altered by UV light or ambient temperature.The storage modulus(G')decreases with the increase of temperature,when the ambient temperature is changed form low temperature(O?)to room temperature(25?)expressing G' at 50000 Pa and 5000 Pa,respectively.Under the same test conditions,the intensity of gel sample after UV illumination decreased by 2000 Pa,compared with the sample before UV light,the intensity of hydrogel had significant change.3 Polyvinylimidazolium ionic liquids containing azobenzene/bromobenzyl functional groups were prepared.The structure was determined by 1H-NMR and FT-IR,the microscopic changes in the phase transition of the poly(ionic liquid)s were simulated using the model compound.In the process of preparing the phase inversion system,we found that the mixture solution of poly(ionic liquid)s with specific feed ratio exhibited UCST behavior.The influence of different rate of feed on polymer system was discussed,TF-IR spectroscopy,turbidimetric method and 1H NMR were used to investigate the mechanism of phase behavior.