Structuring of polymer nanocomposites (PNCs) with an aid of relatively weak external magnetic fields has been studied as a method for control of the nano‐ and microstructure. Magnetic nanoparticles (NPs) were assembled into high aspect ratio one‐dimensional strings and unidirectionally oriented with the magnetic field (B = 0–50 mT) within the photopolymer matrix. The effect of the anisotropic MNPs assemblies on the mechanical properties was studied over a wide temperature range for the first time. The impact of various reinforcing mechanisms was distinguished with respect to the position of the glass transition temperature (T_g). The reinforcing effect exhibits temperature dependency with a maximum ~65°C above the glass transition and only negligible effect below the T_g. In addition, significant directional anisotropy of stiffness was observed. Composite micromechanics was applied to interpret the orientation and size‐dependent reinforcement of PNCs, and temperature‐dependent stiffness of the polymer‐MNP structures was quantified. The presence of polymer chains with altered dynamics surrounding the MNPs inside the anisotropic assemblies was proposed to be an essential nanoscale mechanism mediating the stress transfer and contributing to mechanical robustness of the hybrid structures and PNCs. POLYM. ENG. SCI., 60:587–596, 2020. © 2019 Society of Plastics Engineers

中文翻译：

---

聚合物纳米复合材料中节段尺度硬化向宏观尺度增强的转化

作为一种控制纳米和微观结构的方法，已经研究了借助相对弱的外部磁场来构造聚合物纳米复合材料（PNC）的方法。磁性纳米颗粒（NPs）被组装成高纵横比的一维线串，并在光敏聚合物基质内的磁场（B = 0–50 mT）的作用下单向取向。首次在较宽的温度范围内研究了各向异性MNPs组件对机械性能的影响。关于玻璃化转变温度（T _g）的位置，区分了各种增强机制的影响。增强作用表现出温度依赖性，在玻璃化转变温度以上最大〜65°C，而在玻璃化转变温度以下的影响很小Ť_克。另外，观察到明显的刚度方向各向异性。用复合微力学解释了PNC的取向和尺寸依赖性增强，并对聚合物MNP结构的温度依赖性刚度进行了量化。各向异性链内围绕MNP的动力学改变的聚合物链的存在被认为是介导应力传递并有助于混合结构和PNC的机械强度的基本纳米级机理。POLYM。ENG。SCI。，60：587–596，2020.©2019塑料工程师协会