(551d) Megasupramolecules in Extremely Non-Polar Solvents: What to Do When 3000+ Backbone Units Fail to Drag Two End-Groups into Solution?

Megasupramolecules are long end-associative polymers with hydrogen-bonding end-groups that associate in solution at low concentrations to form multimillion molecular weight supramolecules. The reversible dissociation of the end-groups protects the backbone from shear degradation, overcoming the disadvantages of conventional ultralong polymer additives.

Megasupramolecules can be used as shear-resistant mist-control agents to make fuels safer by reducing the risk of mist fires, and also as drag-reducing agents to reduce the energy cost of transporting fuels through pipelines. Currently, megasupramolecules are made of polycyclooctadiene backbones (akin to polybutadiene) and are soluble in jet-fuels and in some organic solvents (e.g., cyclohexane, tetralin, decalin). This research focuses on expanding the applicability of megasupramolecules to highly nonpolar solvents, using polyalphalolefin (PAO) as the model solvent.

The challenge in highly non-polar solvents is limited solubility. Surprisingly, we found that although the polymer end-groups account for less than 0.1% of the total polymer molecular weight, they impact the solubility of the polymers significantly. To overcome this challenge, we used various co-solvents and co-solutes to solubilize the end groups via aromatic-aromatic or aromatic-aliphatic interactions, without compromising their hydrogen bonding ability. The use of co-solvents and co-solutes allowed dissolution of megasupramolecules in PAO at room temperature and provided new insight into the role of end-group/solvent interaction in the assembly of megasupramolecules.