Synthesis And Properties Of Transparent Polyimides Derived From 1,4-diaminocyclohexane Via Aromatic Nucleophilic Substitution Polymerization

With the development of science and technology, transparent polyimide materials with high temperature resistance and transparency have been attracted extensive attention around the world, which could be used as substract materials in flexible solar cells, flexible display and lighting instead of fragile glass. However, the yellow color of polyimides limits their application in these areas. Therefore, study on the structure-property relations of the polyimides is of great significance to their development and application of these materials. Thus, this thesis is focused on synthesis and properties of transparent polyimides based on 1,4-diaminocyclohexane via aromatic nucleophilic substitution polymerization, as follows:1. A series of transparent polyimides derived from 1,4-diaminocyclohexane was synthesized using phenolphthaleins and bis(fluorophalimide)s as monomers via aromatic nucleophilic substitution polymerization. It was found that:(1) the glass transition temperatures(Tgs) of polyimides were between 275-312 ℃, and increased with the increase of the proportion of trans-1,4-diaminocyclohexane;(2) the polyimides showed good thermal stability and solubility;(3) the polyimide films exhibited good transparency with cutoff wavelengths of 350-355 nm and transmittances over 80% at 400 nm wavelength.2. A series of transparent polyimides derived from 1,4-diaminocyclohexane was synthesized using 4-fluorophenylsulfone and bis(hydroxylphalimide)s as monomers via aromatic nucleophilic substitution polymerization. It was found that:(1) the glass transition temperatures(Tgs) of polyimides were between 259-295 ℃, and increased with the increase of the proportion of trans-1,4-diaminocyclohexane;(2) the polyimides showed good thermal stability;(3) the polyimide films exhibited good transparency with cutoff wavelengths of 347-349 nm and transmittances over 80% at 450 nm wavelength.