Architecture and polymeric liquid elasticity

随着我们最近在结构-性质关系方面的突破[POF，31，087107（2019）]，我们现在设计大分子，用珠棒模型近似它们的形状，并将这些模型转化为对它们作为弹性液体的行为的准确预测。然后，我们探讨如何改变分子结构影响这些行为的弹性液体。我们要么逐个结构地这样做，要么对某些重要类别的大分子，通过不断改变它们的形状来这样做。例如，我们已经发现，对于四面体分支，增加内角首先增加然后降低其弹性[POF，33，093111（2021）]。我们最近的工作集中在商业上重要的问题，增加支化的大分子，以改善其加工性能。我们致力于我的就职发现补助金和加拿大研究主席探索振荡剪切流，因为它是最流行的粘弹性测量，它揭示了丰富多样的有趣的细节非线性粘性和弹性部分的复杂液体响应。因此，我们通过建立DNA、星形支化聚合物、二嵌段共聚物、石墨烯和包括冠状病毒在内的许多病毒的结构-性质关系，加深了对所选流变学领域的理解。在接下来的五年里，我们将大胆地攻击（1）已经合成或尚未想象的最复杂的结构，（2）不对称大分子结构的未开垦领域，（3）探索奇异非线性变形（LAOS和稳态剪切流）的结构-性质关系，以及（4）使用我们独特的实验装置来测量这种非线性流动引起的取向。关于（4），我们将比较流体弹性与竞争纠缠理论的贡献。对于这项发现补助金，我建议利用我的女王实验室，该实验室现在配备了测量流变非线性变形的最新突破性仪器：带板分割的锥板流动。我设计这个建议是为了利用我在流体物理学方面的新加拿大研究主席的资源。我们寻求发现资助博士后和博士生的支持，以评估结构理论的最新进展，并对已知分子结构的聚合物液体进行仔细测量。

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.