Comparison of Rheological Properties of Short-chain Perfluoropolyethers through Simulation and Experiment

Four short-chain perfluoropolyethers (PFPEs) with varied architectural modifications have been studied rheologically using non-equilibrium molecular dynamics simulation and experiment. An explicit-atom potential, which treats all fluorine atoms equivalently, is not capable of reproducing the experimentally observed trends in viscosity among the four compounds. Rather, the parameters of the potential governing the interaction of fluorine must reflect the proximity of the fluorine to the oxygen in the ether linkage. Defining four different types of fluorine atoms, we are able to reproduce the experimentally observed trends in viscosity among the four compounds. We examine the effect of this potential change on the structural properties as well.