MEH-PPV:  Improved Synthetic Procedure and Molecular Weight Control

Mechanistic studies on the polymerization of α,α‘-dibromo-2-methoxy-5-(2-ethylhexyloxy)xylene have been performed. Polymerizations were initially carried out by adding potassium tert -butoxide to monomer in the presence of a chain transfer agent, anthracene. Anthracene showed little effect on the molecular weight of the resulting polymer, suggesting that the major polymerization route was not radically initiated. Polymerizations were also carried out by adding monomer to potassium tert -butoxide in the presence of a nucleophile, 4-methoxyphenol. The molecular weight of the resulting polymer scaled linearly with the amount of 4-methoxyphenol, suggesting an anionic mechanism. In addition, each polymerization was monitored by in-situ torque measurements to further elucidate the polymerization mechanism and optimize polymerization conditions.