Effect of the Interactions between Polymers and Solid Fillers on the Structure of Polymer-Filler

作为第一个项目期的总结阶段，目前提议的项目旨在从根本上、全面地了解聚合物与固体填料的相互作用对填充聚合物熔体的填料-聚合物界面结构、聚合物介导力、填料团聚和相关流变性的影响。根据所提出的理论发展，我们打算计算作为填料分离、聚合物密度、填料表面对被吸附聚合物的亲和力以及聚合物聚合度的函数的填料之间的聚合物介导力。此外，我们还将根据填料表面与聚合物之间的微观相互作用来研究吸附聚合物层的密度结构。我们将使用态密度蒙特卡罗模拟来计算聚合物介导力和吸附聚合物层的结构，目的是验证我们的理论发现。利用计算的聚合物相互作用作为输入，我们将得到聚合物-颗粒复合材料在填料和聚合物之间存在吸附相互作用时的状态方程。此外，我们还打算研究聚合物在颗粒-胶体复合材料中的诱导相分离，并用这一结果来解释聚合物颗粒混合物中聚合物桥联辅助的填料聚集。在所提出的理论方法中，我们将分别描述填料之间可逆和不可逆的聚合物桥联的情况。对于聚合物不可逆桥接的情况，我们将基于精确的统计物理模型来研究聚合物熔体中填料的‘桥联絮凝’和填料团簇聚集体(絮体)的形成。这项研究包括研究聚合物介导的絮凝体之间的相互作用及其对填充的聚合物熔体剪切粘度的影响。在拟议项目的最后阶段，我们将通过开发和利用包含这些相互作用的自洽动力学模型，从微观聚合物-填料以及由此产生的聚合物中介的填料-填料相互作用入手，研究填充熔体的选定流变性。

As a conclusive stage of the first project period that logically extends its findings, the currently proposed project aims at gaining fundamental, comprehensive understanding of the effects of the interaction of polymers with solid fillers on the structure of the filler-polymer interfaces, polymer mediated forces, filler agglomeration and associated rheological properties of the filled polymer melts. Relying on the proposed theoretical development, we intend to calculate the polymer mediated force acting between fillers as a function of the filler separation, polymer density, affinity of the filler surface for the adsorbed polymers, and the degree of polymerization of polymers. In addition, we will investigate the density structure of the adsorbed polymer layers depending on the micoscopic interactions between the filler surface and polymers. We will use the Density-of-state Monte Carlo simulations to calculate the polymer mediated force and the structure of the adsorbed polymer layers with the objective to verify our theoretical findings. Using the calculated polymer-mediated interactions as an input, we will obtain the equation of state of the polymer-particle composite in the presence of the adsorption interactions between the fillers and polymers. In addition, we intend to investigate the polymer-induced phase separation in the particle-colloid composites and use the result in explaining the polymer bridging-assisted filler aggregation in the polymer particle mixtures. In the proposed theoretical approach, we will separately describe the cases of reversible and irreversible polymer bridging among fillers. For the case of irreversible bridging by polymers, we will investigate the 'bridging flocculation' of the fillers in the polymer melts and the formation of filler cluster aggregates (flocs) based on the exact statistical physical model. This study includes investigating the polymer-mediated interactions among flocs and their effect on the shear viscosity of the filled polymer melt. In the final stage of the proposed project, we will study the selected rheological properties of filled melts starting from microscopic polymer-filler and resulting polymer-mediated filler-filler interactions, through developing and making use of the self-consistent dynamic model incorporating those interactions.