Determinants of π-π Stacking Motifs in Polymers with Different Aromatic Side Groups

In this study, all-atom molecular dynamics simulations, supported by Wide-Angle X-ray Scattering (WAXS) data, are used to investigate π-π stacking motifs in five polymers containing different aromatic side groups: polystyrene (PS), poly(2-vinylnaphthalene) (P2VN), poly(1-vinylnaphthalene) (P1VN), poly(4-vinylbiphenyl) (PVBP), and poly(acenaphthylene) (PACN). The probabilities of each π-π stacking motif (T-shaped, sandwich, and parallel displacement) formed between adjacent side groups are statistically evaluated for all polymers studied. The tendency to form stacking motifs of sandwich and parallel displacements shows a strong correlation with both higher torsional free energy barriers and greater spatial segregation of opposite electrostatic potentials in these polymers. Moreover, the results highlight the critical role of the overlap distance between aromatic side groups on adjacent chains in governing inter- or intra-chain π-π interactions.