The structure of poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) solutions with a number of common deuterated organic solvents was studied by means of (1)H NMR spectroscopy The resonance bands of the polymer backbone protons appear at much lower frequencies in CDCl(3) compared to their positions in aromatic solvents This has been attributed to the pi-pi self-stacking interaction of the polymer segments in the aliphatic solvent, which is replaced by a polymer-solvent pi-pi interaction in the aromatic solvents. In mixed solvent systems with an aliphatic solvent component and an aromatic one, the intensifies of the polymer resonances pass through a maximum at intermediate solvent compositions. This has been attributed to the minimum aggregation tendency of the polymer at these solvent compositions. The results suggest that a mixed solvent system constituting an aliphatic component and an aromatic component might be a choice for casting films of hairy-rod type conjugated polymers if minimization of aggregate domains in the films is desired.
