Established model theories, developed to capture the mechanical behavior of soft complex materials composed of semiflexible polymers assume entropic interactions between filaments to determine the mechanical response. In recent studies, the general accepted tube model has been challenged in terms of its basic assumption about filament-filament interactions, but also because of its predictions regarding the frequency dependence of the elastic modulus in the intermediate frequency regime. A central question is how molecular interactions and friction between network constituents influence the rheological response of isotropic entangled networks of semiflexible polymers. It was shown that friction forces between aligned pairs of actin filaments are not negligible. Here, we systematically investigate the influence of friction forces and attractive interactions on network rheology by means of a targeted surface modification. We show that these forces have a qualitative and quantitative influence on the viscoelastic properties of semiflexible polymer networks and contribute to the response to nonlinear deformations. By comparing two polymer model systems with respect to their surface compositions we give a possible explanation about the origin of acting forces on a molecular level.

中文翻译：

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科学摩擦故事——半柔性聚合物网络中的分子相互作用

已建立的模型理论旨在捕捉由半柔性聚合物组成的软复合材料的机械行为，假设细丝之间存在熵相互作用以确定机械响应。在最近的研究中，普遍接受的管模型在其关于灯丝-灯丝相互作用的基本假设方面受到挑战，但也因为它对中频区域中弹性模量的频率依赖性的预测。一个中心问题是网络成分之间的分子相互作用和摩擦如何影响半柔性聚合物各向同性缠结网络的流变响应。结果表明，对齐的肌动蛋白丝对之间的摩擦力不可忽略。这里，我们通过有针对性的表面改性系统地研究了摩擦力和吸引力相互作用对网络流变学的影响。我们表明，这些力对半柔性聚合物网络的粘弹性有定性和定量的影响，并有助于对非线性变形的响应。通过比较两种聚合物模型系统的表面组成，我们给出了在分子水平上作用力起源的可能解释。