Synthesis by the Gilch Method of Blue-Light-Emitting Poly(p-phenylenevinylene) Derivatives Bearing Highly Phenylated Pendants

Abstract

Two novel poly(p-phenylenevinylene) (PPV) derivatives bearing highly phenylated side groups with different chemical structures were prepared by Gilch dehydrohalogenation polyaddition. The intermediate substituted 1,4-bis(bromomethyl)benzenes (monomers 6 and 11) were synthesized by a convenient synthetic route utilizing pyrylium salts. The polymers were amorphous and showed limited solubility in THF, chloroform, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, and 1,2-dichlorobenzene. They displayed relatively high Tg values (158−176 °C) and good thermal stability, being stable up to approximately 270−350 °C in N2 or air and affording anaerobic char yields of 53−56% at 800 °C. The bulky side groups caused a significant steric effect on the PPV backbone and reduced the chromophore length. The solutions of polymers in THF emitted blue light with a maximum around 455 nm. This emission maximum is blue-shifted in comparison with that of other previously synthesized PPVs that emit green to red light. At low temper...