Abstract
Non-hydrogen bonding van der Waals liquids with dipole-dipole interactions are typically viewed as non-associative and not considered able to sustain large supramolecular structures. Combining broadband dielectric spectroscopy (BDS) and rheology, we demonstrate the supramolecular formation in a group of non-hydrogen bonding van der Waals liquids, i.e., 1-bromo-2-ethylhexane, 1-chloro-2-ethylhexane, and 1-bromo-3,7-dimethyloctane. BDS shows an emergence of a Debye-like process slower than their structural relaxation, which follows super-Arrhenius temperature dependence. Meanwhile, rheological measurements reveal a noticeable dynamical separation between the terminal relaxation and the structural rearrangements. Interestingly, the rheological terminal time agrees remarkably well with the dielectric Debye-like relaxation time, pointing to a strong coupling between the terminal flow and the supramolecular dynamics of these van der Waals liquids. These results highlight a key role of intermolecular dipole-dipole interaction in the supramolecular structure formation and the slow dynamics of van der Waals liquids.
| Original language | English |
|---|---|
| Article number | 134501 |
| Journal | Journal of Chemical Physics |
| Volume | 163 |
| Issue number | 13 |
| DOIs | |
| State | Published - Oct 7 2025 |
Funding
This work was supported by the Michigan State University Discretionary Funding Initiative (MSU-DFI). The authors would like to thank Sean Walsh and Professor Robert Malezcka’s group from the Department of Chemistry at Michigan State University for their help on the purification and characterization of 2E1Br and 3,7D1OBr. We thank Dr. Shinian Cheng at the University of Tennessee for helping with the DSC measurements of 2E1Br.