Magnetic composite materials i.e. elastomers, polymer gels, or polymer solutions with embedded magnetic nanoparticles are useful for many technical and bio-medical applications. However, the microscopic details of the coupling mechanisms between the magnetic properties of the particles and the mechanical properties of the (visco)elastic polymer matrix remain unresolved. Here we study the response of a single-domain spherical magnetic nanoparticle that is suspended in a polymer solution to alternating magnetic fields. As interactions we consider only excluded volume interactions with the polymers and hydrodynamic interactions mediated through the solvent. The AC susceptibility spectra are calculated using a linear response Green–Kubo approach, and the influences of changing polymer concentration and polymer length are investigated. Our data is compared to recent measurements of the AC susceptibility for a typical magnetic composite system [Roeben et al., Colloid Polym. Sci., 2014, 2013–2023], and demonstrates the importance of hydrodynamic coupling in such systems.

中文翻译：

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聚合物溶液中磁性纳米粒子的频率相关磁化率：模拟研究

磁性复合材料即弹性体，聚合物凝胶或带有嵌入磁性纳米粒子的聚合物溶液可用于许多技术和生物医学应用。但是，颗粒的磁性和（粘）弹性聚合物基体的机械性能之间的耦合机理的微观细节仍未解决。在这里，我们研究了悬浮在聚合物溶液中的单畴球形磁性纳米粒子对交变磁场的响应。作为相互作用，我们认为仅排除了与聚合物的体积相互作用以及通过溶剂介导的流体动力学相互作用。使用线性响应Green-Kubo方法计算AC磁化率谱，并研究变化的聚合物浓度和聚合物长度的影响。等。，胶体Polym。科学 ，2014，2013–2023]，并证明了液力耦合在此类系统中的重要性。