A poly ( p-phenylenevinylene ) ( PPV ) alternating copolymer, poly [ ( 2, 5-diphenylene-1, 3, 4-oxadiazole )-4-4' - vinylene-alt-2-methoxy-5-( 2-ethylhexyloxy )-1, 4-phenylenevinylene] (oxa-MEHPV), is synthesized by Heck coupling reaction and characterized with UV-vis, Fourier transform infrared ( FT-IR ), ^1H-NMR and photoluminescence ( PL ) spectroscopy, oxa-MEHPV possesses an outstanding thermal stability and shows excellent solubility in common organic solvents such as dichloromethane, chloroform, toluene, and tetrahydrofuran(THF). The introduction of the electron-deficient 1, 3, 4-oxadiazole units into the MEH-PPV backbone also increases the electron affinities of the conjugated segment, which leads to the blue-shift of the maximum absorption wavelength and makes the polymer have a high optical band-gap energy, good electron-transporting stability and high PL quantum yield.
Two new diarylamine-substituted 1, 8-naphthalimide derivatives are synthesized by Cu I/18-crown-6/K2CO3 catalyst system and characterized by Fourier transform infrared (FT- IR), ^1H-NMR and elemental analyses. The UV-vis absorption and photoluminescent (PL)spectra of the systems in n-hexane, tetrahydrofuran(THF), and CH2Cl2 are investigated. These naphthalimide molecules have an absorption band centered at about 450 nm, which is assigned to an intramolecular chargetransfer (ICT)transition, and they emit light at 492, 501 nm in a nonpolar solvent such as n-hexane, and at 600, 620 nm in a polar solvent such as CH2Cl2. From the Lippert-Mataga equation, the difference of the dipole moment between the excited state and the ground state is estimated to be 9.2 and 9.8 D for 4- ( diphenylamine )-N-( 2-methoxyphenyl )-1, 8-naphthalimide ( DMN-1 ) and 4-( 2-naphthylphenylamine )-N-( 2- methoxyphenyl)-1, 8-naphthalimide (DMN-2), respectively. This large change in the dipole moment upon excitation is typical for photoinduced ICT processes.
For the production of reactive polyurethane cross-linkinger and curing agents, 2, 4-diisocyanate toluene (TDI) terpolymer, which possesses the rigid structures of hexatomic ring and three reactive functional groups, was synthesized and characterized by the Fourier transform infrared (FFIR), the gel permeation chromatography (GPC) and the chemical analysis methods. The reaction conditions were studied and optimized. A tracking research on the polymerization process of TDI was taken by using the GPC. The formation processes of the terpolymer, oligomers and higher-polymers were also dealt with. Results show that the TDI terpolymer can be prepared in the presence of Cat-3 catalyst and at the reaction temperature of (60 ±2)℃. The reaction time is short, its outcomes have narrow molecular weights distribution, namely molecular weights from 530 to 550, Mw/Mn =1.10, and the mass fraction of NCO is (25. 0 ± 0. 5)%. With the reaction time prolonging, however, TDI can be further higher-polymedzed to form higher-polymers. Benzoyl chloride (0. 4%, mass fraction), as the stabilizing agent, can effectively inhibit the occurrence of higher-polymerization. The obtained TDI terpolymer can be stable for more than half a year.