Control of conjugation in poly(arylenevinylene)s

Poly(1,4-phenylenevinylene) (PPV) and derivatives have been studied extensi vely for use in polymer based LEDs. It has been shown that the introduction of low levels of saturated units into the polymer backbone can give LEDs w ith improved efficiency. We have developed a new route to partially conjuga ted PPV derivatives enabling the final polymer to be formed with ethylene l inks bearing no leaving groups. This was achieved by the treatment of the c hloro precursor to poly{2-(2'-ethyl)hexyloxy-5-methoxy-1,4-phenylenevinylen e} (MEHPPV) with different amounts of tri-n-butyltin hydride to form copoly mers which contain selected proportions of unsubstituted and chlorine subst ituted ethylene linkages. The subsequent thermal conversion gave rise to co njugated copolymers containing ethylene and vinylene linkages.