Simple improvements to Gilch synthesis and molecular weight modulation of MEH-PPV†
The solvent and temperature used in the Gilch synthesis of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) were varied to achieve an improved set of reaction conditions. A range of molecular weights from 20 to 500 kg mol−1 were obtained in moderate to near-quantitative yields. The best conditions for producing low molecular weight MEH-PPV (32 kg mol−1, 97% yield) was to use n-pentane as the reaction solvent at 25 °C. For high molecular weight (397 kg mol−1, 65% yield), toluene at 55 °C gave the best result. The photophysical properties for all MEH-PPV samples were examined and no significant variation was found between samples obtained under different polymerization conditions.