The Synthesis And Characterization Of Functional Polyimide

Polyimides have been well known as high performance materials for their excellent thermaland dimensional stabilities, mechanical and electrical properties, and facilities for molecular designthroughchemicalsynthesis.Inrecent years,functionalpolyimideshavebeenwidelyusedinorganicoptoelectronic devices such as organic memory devices, organic light-emitting diode, organicthin-filmtransistor,andsolarcelletal.In this dissertation, we did scientific research from three aspects: (1), increasing its solubilityfor film formation capability by chemical modification, while still maintain the excellentperformanceofpolyimides;(2),usingamatureway,whichisdifferentfromthetraditionalone-stepor two-step method of preparation of polyimide, to prepare the functional polyimides via Suzukipolymerization; (3), exploring the possibility of aliphatic polyimide containing functional sidegroupsusedinoptoelectronicdevicesviapost-polymerizationreaction.Thedissertationisdividedintofivechapters.In Chapter 1, the basic principles of three kinds of optoelectronic devices(OrganicLight-emitting Diode, Organic Memory Device and Solar cell) were introduced briefly, anddifferent types of polyimides for their corresponding device applications were summarized anddiscussedindetail based ontheproperty-structure relations. Finally, the research interests and mainworkofthisdissertationareputforwardaccordingly.In Chapter 2, two kinds of fluorenyl Cardo polyimides were synthesized, and these twopolyimides maintain good mechanical properties and thermal stabilities, but exhibit good solubilityin common organic solvents, overcoming the traditional aromatic polyimide problem of poorsolubility, The results show that the introduction of fluorenyl cardo groups into the backbone ofpolyimides is an effective approach for improving solubility and thereby processability ofpolyimideswithoutsacificingthethermalpropertiesofpolyimides.In Chapter 3, we successfully synthesized a key monomer——dibromo-phenylhexafluorobenzene imide, which containing imide ring. Three different contents of copolymersderived from dibromo-phenyl hexafluorobenzene imide, 2,7-bis(cyclopropane boric acidester)-9,9'-dioctylfluorene and 9,9'-dioctyl-2,7-dibromo fluorene were successfully prepared bysuzuki coupling copolymerization. Chemical structures and optoelectronic properties of the polyimides were characterized and the polymers exhibit excellent solubility in common organicsolvents such as THF and CDCl3. This method to prepare polyimide has the advantage of easyprocessing for one hand, and adopted mature polymerization for another hand, enriching thesyntheticroutesoffunctionalpolyimides.In Chapter 4, aliphatic polyimide which has electron-withdrawing main chain were preparedby conventional methods. Then, under alkaline condition, N-bromohexyl carbazole as an electron-donating side group connected into the aliphatic polyimide main chain. The functional polyimidewere characterizedand testedtoobservetheirsolubilities, thermal properties andoptical properties,whichsuggesthighpotentialofaliphaticpolyimidetobeusedinoptoelectronicdevices.InChapter5,aseriesofrelatedconclusionsofthisdissertationweresummarized.