Exploring the Dithiocarbamate Precursor Route: Observation of a Base Induced Regioregularity Excess in Poly[(2-methoxy-5-(3 ',7 '-dimethyloctyloxy))-1,4-phenylenevinylene] (MDMO-PPV)

The dithiocarbamate precursor route is a suitable way to synthesize poly(p-phenylene vinylene) derivatives in an efficient manner. It is demonstrated that this precursor route combines the straightforward monomer synthesis of the Gilch route with the superior polymer quality of the more complex sulfinyl route. To obtain the polymers, the bisdithiocarbamate MDMO monomer has been polymerized using either lithium bis(trimethylsilyl)amide (LHMDS) or potassium tert-butoxide (KtBuO). The addition of either base results in the formation of high molecular weight precursor polymer. It is shown that the polymerization mechanism follows a radical pathway. Furthermore it is demonstrated that the molecular structure of the polymer shows a certain degree of regioregularity when LHMDS is used. The thermal conversion of the precursor polymer into the conjugated system is studied by in situ UV-vis and FT-IR spectroscopy. A NMR study on C-13-labeled MDMO-PPV reveals the presence of only a minimal amount of structural defects in the microstructure of the polymer, further confirming the excellent characteristics of the dithiocarbamate precursor route.