This paper describes a simple new strategy for preparing poly(9,9-dialkylfluorenyl-2,7-vinylenes) (PFVs) having high molecular weights and no detectable saturated defects along the conjugated backbone. The new route utilizes a modified Horner-Emmons method by coupling suitably designed comonomers to form the targeted conjugated polymers. The newly prepared PFVs were directly compared to PFVs prepared via a previously established Gilch polymerization route. The structure and optical properties of all PFVs were characterized by gel permeation chromatography (GPC), NMR spectroscopy, UV-vis, fluorescence, and photoluminescence spectroscopy. The findings indicate that the modified Horner-Emmons route gave PFVs with lower molecular weights but substantially higher yields and fewer defects than those prepared by using the Gilch route.

A new method is described for the synthesis of soluble poly(1-methoxy-4-(2-ethylhexyloxy)-p-phenylenevinylene) (MEH−PPV) using N,N-dimethylformamide (DMF) as the solvent. Based on a modification of the traditional Gilch method, the polymerization of α,α‘-dibromo-2-methoxy-5-(2-ethylhexyloxy)xylene was conducted in DMF under a variety of experimental conditions. The resultant MEH−PPVs were characterized and compared to those prepared using analogous syntheses in tetrahydrofuran (THF). Characterization techniques included 1H NMR spectroscopy, UV−vis spectroscopy, and gel permeation chromatography (GPC). Although the molecular weights of the polymers prepared in DMF were routinely lower than those prepared in THF, the polydispersities were as low as (and in most cases lower than) those obtained using THF. Significantly, the use of DMF in polymerizations conducted at 100 °C led to no gelation of the polymer, which circumvented the need for any controlled addition of monomer during the reaction. Moreover, control over the polymer molecular weights in DMF could be achieved using chosen aliquots of the molecular weight modifier 4-(tert-butyl)benzyl bromide and/or by controlling the concentration of the reactants.