Novel organic and inorganic ionogels: preparation and characterization
Date
2013-07-01
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Abstract
Ioonsed vedelikud ehk ümbritseval temperatuuril vedelad soolad on pälvinud tähelepanu mitmesugustes rakendustes tänu oma unikaalsetele füüsiko-keemilistele omadustele, nagu madal aururõhk, keemiline ja termiline stabiilsus, küllaltki hea elektrijuhtivus ning mitmekülgsed solvateerivad omadused. Teatud rakendustes ei ole vedelikud voolavusest tingitud lekkimisohu tõttu siiski sobivad ning seega on vaja leida võimalusi, kuidas siduda ioonseid vedelikke tahkesse faasi nii, et nende omadused säiliksid. Ionogeelid on hübriidmaterjalid, milles ioonne vedelik on seotud kolmedimensionaalse tahke võrgustikuga ehk geeliga. Käesolevas doktoritöös töötati välja kaks uudset ionogeeli, mis geeli ja ioonse vedeliku interaktsioonide ning geeli omaduste tõttu liigituvad orgaaniliseks ja anorgaaniliseks keemiliseks ionogeeliks.
Polümeerid on levinud maatriks orgaaniliste ionogeelide valmistamiseks. Käesolevas doktoritöös töötati välja läbipaistev, painduv ja elektrit juhtiv orgaaniline ionogeel, mis koosneb metakrülaat-tüüpi polümeriseeritud ioonsest vedelikust ja traditsioonilisest ioonsest vedelikust, 1-etüül-3-metüülimidasoolium tetrafluoroboraadist ([EMIM][BF4]). Väljatöödatud uudsete hübriidmaterjalide juhtivus sõltub lisatud [EMIM][BF4] sisaldusest ning on kuni suurusjärgu võrra kõrgem võrreldes polümeriseeritud ioonsete vedelikega (juhtivuse kasv 10-5 S cm-1-lt 10-4 S cm-1-le).
Teine käesolevas töös välja pakutud uudne hübriidmaterjal on hüdrasiinium-ioonsel vedelikul baseeruv anorgaaniline ionogeel. Töötati välja sünteesimeetod hüdrasinosilaanide valmistamiseks. Analoogilisi aminosilaane on laialdaselt kasutatud mitmesuguste funktsionaalsete pinnakatete valmistamisel ja biomolekulide immobiliseerimisel. Sarnaselt aminosilaanidele, võimaldab hüdrasinorühma kvaterneerimine valmistada ioonseid vedelikke ja sool-geel prostessil vastavaid ionogeele. Hüdrasinosilaanidel ja hüdrasiinium ioonsetel vedelikel on võrreldes aminosilaanide ja ammooniumsooladega mitmeid struktuurist tulenevaid eeliseid, mille rakendusvõimalused vajavad täiendavat uurimist.
Ionic liquids are at ambient temperature liquid salts. In the present thesis the preparation of chemical organic and inorganic ionogels as a method for immobilizing ionic liquids was investigated. Immobilization of ionic liquids in solid state while retaining their extraordinary physico-chemical properties is needed for several practical applications where the fluidity of ionic liquids leads to problems related to leakage and difficulties in obtaining or maintaining a predefined physical shape of the material. In the present thesis novel organic ionogels were prepared by mixing methacrylate type polymerized ionic liquids (PILs) with 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]; 10-75% v/v). The motivation of addition of [EMIM][BF4] was to prepare transparent and flexible materials with higher conductivity than that of neat PILs. The results of the current thesis show that by mixing PILs with conventional ionic liquid the conductivity increase about an order of magnitude (from 10-5 to 10-4 S cm-1) can be achieved. The sol-gel process is a convenient and flexible method for the preparation of inorganic ionogels. In the current thesis hydrazinosilanes as an alternative for silyl functionalized imidazolium or ammonium ionic liquids were proposed as starting materials for inorganic chemical ionogels. The preparation of hydrazinosilanes has not been reported prior to the synthesis of 3-hydrazinopropyl trimethoxysilane carried out in the present thesis. The motivation for preparation of hydrazinosilanes were their potential advantages compared to analogous aminosilanes, like stability in broader pH range and chemical versatility due to additional amino group. The quaternization of prepared hydrazinosilane and potential applications for hydrazinium ionic liquids based ionogels need further investigations.
Ionic liquids are at ambient temperature liquid salts. In the present thesis the preparation of chemical organic and inorganic ionogels as a method for immobilizing ionic liquids was investigated. Immobilization of ionic liquids in solid state while retaining their extraordinary physico-chemical properties is needed for several practical applications where the fluidity of ionic liquids leads to problems related to leakage and difficulties in obtaining or maintaining a predefined physical shape of the material. In the present thesis novel organic ionogels were prepared by mixing methacrylate type polymerized ionic liquids (PILs) with 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]; 10-75% v/v). The motivation of addition of [EMIM][BF4] was to prepare transparent and flexible materials with higher conductivity than that of neat PILs. The results of the current thesis show that by mixing PILs with conventional ionic liquid the conductivity increase about an order of magnitude (from 10-5 to 10-4 S cm-1) can be achieved. The sol-gel process is a convenient and flexible method for the preparation of inorganic ionogels. In the current thesis hydrazinosilanes as an alternative for silyl functionalized imidazolium or ammonium ionic liquids were proposed as starting materials for inorganic chemical ionogels. The preparation of hydrazinosilanes has not been reported prior to the synthesis of 3-hydrazinopropyl trimethoxysilane carried out in the present thesis. The motivation for preparation of hydrazinosilanes were their potential advantages compared to analogous aminosilanes, like stability in broader pH range and chemical versatility due to additional amino group. The quaternization of prepared hydrazinosilane and potential applications for hydrazinium ionic liquids based ionogels need further investigations.
Description
Väitekirja elektrooniline versioon ei sisalda publikatsioone.
Keywords
ioonsed vedelikud, geelid, hübriidmaterjalid, ionoc liquids, gels, hybrid materials, ioonsed vedelikud, geelid, hübriidmaterjalid, ionic liquids, gels, hybrid materials