Substituted PPV's for blue light

Conjugated polymers based on poly(1,4-phenylenevinylene) (PPV) have provided one of the foundations for polymer based LED's. One of the important routes to these materials is to polymerise a substituted 1,4-bis(halomethylene)benzene to form a soluble halo precursor polymer which is then thermally treated to give the final conjugated polymer. We have been investigating the effect of varying the vinylic substituent on the preparation of sterically congested polymers. We have found that electronic effects play a major role in controlling the polymer molecular weight by comparing the syntheses of PPV's substituted on the vinylene moiety.