Synthesis and properties of alkyl substituted poly(1,4-phenylenevinylene) derivatives

A new synthetic route was designed for synthesizing the luminescent polymers of alkyl substituted poly(1, 4-phenylenevinylene) derivatives (alkyl-PPV). The monomer of the polymers was synthesized by two steps:first, using Li2CuCl4 to catalyze cross-coupling of aryl grignard reagent with alkyl halides to introduce alkyl long-chained substituents to benzene ring, second, using SnCl4 to catalyze chloromethylation of the alkyl long-chained substituted benzene. The yield of the monomer synthesized by this method was much higher than that by any other methods that were ever reported. The polymerization of the monormer was carried out by using t-BuOK to remove HCl. Poly(2-dodecyl-5-methyl-1, 4-phenylenevinylene) was synthesized with that synthetic route. The structure and properties of the polymers were identified and characterized by IR, UV-Vis, luminescent spectra,GPC, thermal (DSC and TGA) and elemental analysis. It was found that the glass transition temperature increases and the photoluminescent relative quantum yield decreases with the increase of the conjugation extent of the polymers, and the photoluminescent relative quantum yield of the polymers can be as high as 78%.