Experimental investigation and numerical simulation of the orientation processes in block copolymers on a macroscopic and a molecular level

该项目的综合目标是更好地了解动态不对称和复杂分子拓扑对均聚物和嵌段共聚物熔体的线性和非线性流变性能的影响。这一目标进一步分为四个工作包：1)需要澄清的是，嵌段共聚物熔体中聚合物嵌段的动态不对称性是否对聚合物片层取向的稳定性有一定的影响。对于相同的迁移率，就像计算机模拟或第一次应用的聚合物系统的情况一样，垂直方向被发现是稳定的方向。然而，在许多实验系统中，可以观察到平行效应。在实验和模拟中应增加迁移率的差异，以评估其对片层取向稳定性的影响。2)另一个需要回答的问题是，片层二嵌段共聚物和片层三嵌段共聚物在剪切过程中片层取向动力学是否存在差异。三嵌段共聚物在一个片层上的固定或在两个不同片层上的固定桥接是否对观察到的体系的取向动力学有显著影响，应予以澄清。3)研究缠结对非线性流变和高次谐波的影响。首先，应研究较不复杂的体系，如均聚物熔体。为了评估分子量的影响，以及缠结的数量，我计划通过使用模拟聚合物链缠结的滑簧和不使用滑簧的模拟来研究模拟中的非线性行为。4)计划研究聚合物拓扑结构的影响。随着侧链数量的增加，缠结对聚合物动力学的影响减小。在模拟和实验中，侧链数目逐渐增加，并对聚合物熔体的非线性行为进行了研究。有了这种方法，就有可能弄清楚高谐波是由纠缠产生的还是由复杂的弛豫谱产生的。

The comprehensive goal of the continuation of this project is a better understanding of the influences like dynamic asymmetries and complex molecular topologies on the linear and nonlinear rheological properties of homopolymer and block copolymer melts. This goal is further divided into four working packages1) It shall be clarified if a dynamic asymmetry of the polymer blocks in block copolymer melts has some influence on the stability of the orientation of polymer lamellae. For identical mobilities, as it is the case in computer simulations or the polymer systems of the first application, the perpendicular orientation is found to be the stable one. However, for many experimental systems the parallel one is observed. The difference in mobility shall be increased in the experiment and in the simulations to evaluate its influence on the stability of the lamellae’s orientation. 2) Another question to answer is if there are differences in the orientation kinetics of lamellae in shear between lamellar diblock copolymers and lamellar triblock copolymers. It shall be clarified if the fixation of triblock copolymers in one lamella or the bridging by a fixation in two different lamellae shows a noticeable influence on the orientation kinetics of the observed system. 3) The influence of entanglements on the nonlinear rheology and on higher harmonics shall be investigated. First, less complex systems as homopolymer melts shall be investigated. In order to evaluate the influence of molecular weight and thus the amount of entanglements, the nonlinear behavior in simulations I planned to be investigated by simulations with slip-springs, which mimic entanglements of polymer chains, and simulations without these. 4) The influence of polymer topology is planned to be investigated. With an increasing number of sidechains the influence of entanglements on the dynamics of the polymer decreases. The number of sidechains is gradually increased in the simulations and in the experiments and the nonlinear behavior of the polymers’ melt is investigated. With this approach it is possible to clarify if higher harmonics result from entanglements or from a complex relaxation spectrum.