Solvatochromic properties of poly[3-(6-methoxyhexyl)-2,5-thienylene] in different solvent mixtures

Two samples of poly[3-(6-methoxyhexyl)-2,5-thienylene] with a slight difference in regioregularity and a greater difference in molecular weights were obtained by chemical oxidation with FeCl3. The solvatochromism of the two polymers was investigated in mixtures of various solvents (dioxane, dimethylpropyleneurea, methylene chloride, tetrahydrofuran, chloroform and toluene) with different non-solvent (methanol) molar fractions, at constant polymer concentration and temperature. Some solvent/non-solvent couples were able to distinguish between the two samples, giving a different solvatochromic effect. This can be considered a very useful tool to characterize polymers with configurational and molecular weight differences.