Solvated poly-(phenylene vinylene) derivatives: conformational structure and aggregation behavior

We study dilute solutions of poly(2,3-diphenyl phenylene vinylene) with hexyl (DP6-PPV) and decyl (DP10-PPV) side chains in two solvents, chloroform and toluene. For this purpose, atomistic and coarse-grained models are parametrized using quantum-chemical calculations and structure-based coarse-graining, respectively. Our simulations indicate that the difference in the aggregation behavior of two derivatives can not be rationalized just in terms of the greater steric hindrance imposed by the longer side chains of DP10-PPV. The coarse-grained model describes qualitatively the DP10-PPV derivative in chloroform, where aggregation does not occur. Although the computed structure factors for this system qualitatively agree with experiments for low concentrations, the calculated persistence length is bigger than the one experimentally reported, hinting at the presence of defects in polymer chains.