Grant: Discovery Grants Program - Individual

With our recent breakthroughs in structure-property relations [POF, 31, 087107 (2019)], we now design macromolecules, approximate their shapes with bead-rod models, and translate these models into accurate predictions for their behaviors as elastic liquids. We then explore how changing the molecular structure affects these behaviors as elastic liquids. We do so either structure by structure, or for certain important classes of macromolecules, by varying their shapes continuously. For instance, we have discovered how, for tetrahedral branching, increasing the interior angle first increases then decreases its elasticity [POF, 33, 093111 (2021)]. Our recent work focuses on the commercially important problems of adding branching to macromolecules, to improve their processability. We have devoted my inaugural Discovery Grant and Canada Research Chair to exploring oscillatory shear flow because it is the most popular viscoelastic property measurement, and it uncovers a rich diversity of interesting detail about the nonlinear viscous and elastic parts of complex liquid responses. We have thus deepened understanding in our chosen field of rheology by establishing structure-property relations for DNA, star-branched polymers, diblock copolymers, graphene and many viruses including the coronavirus. Over the next five years, we will boldly attack (1) the most intricate structures already synthesized or yet to be imagined, (2) the unploughed field of asymmetric macromolecular structures, (3) exploration of structure-property relations for exotic nonlinear deformations (LAOS and steady shear flow) and (4) to use our unique experimental setup to measure the orientation provoked by such nonlinear flows. In regarding (4), we will compare contributions to fluid elasticity with competing entanglement theory. For this Discovery Grant, I propose to exploit my Queen's laboratory, now equipped with the latest breakthrough instrument for measuring rheological nonlinear deformations: cone-plate flow with plate partitioning. I design this proposal to exploit the resources of my renewed Canada Research Chair in Physics of Fluids. We seek Discovery Grant support for postdoctoral and doctoral students to evaluate the latest advances in structural theory with careful measurements on polymeric liquids of known molecular structure.