Abrougui Mariem M, Lopez-Lopez Modesto T, Duran Juan D G
1 Centre National des Recherches en Sciences des Materiaux, Technopole Borej Cedria , BP 73, 8027 Soliman , Tunisia.
2 Faculté des Sciences de Tunis, Université de Tunis El Manar , Tunisie B.P. 94, Rommana 1068 , Tunisia.
Philos Trans A Math Phys Eng Sci. 2019 Apr 22;377(2143):20180218. doi: 10.1098/rsta.2018.0218.
Magnetic gels (ferrogels) are heterogeneous systems structured at the nanoscale that contains magnetic particles dispersed in three-dimensional networks of polymer chains. In the present work, the magnetic particles were synthesized with a core-shell structure, consisting of sepiolite particles covered by magnetite nanoparticles. These composite particles had a rod-like shape with a high aspect ratio. The obtained sepiolite-magnetite particles showed a high enough susceptibility and saturation magnetization. The magneto-rheological (MR) properties, and the intensity of the MR effect, of aqueous suspensions of the synthesized particles were studied. The particles, functionalized by adsorption of alginate molecules, were imbedded in alginate hydrogels to get homogeneous soft materials. The particles were linked to the polymer chains as the knots in a network and dominated in a great extent the mechanical properties of the materials. After determining the optimal compositions of the ferrogels, their viscoelastic properties were measured in the absence/presence of magnetic fields. The results pointed out that the MR effect provided by the clay-magnetite particles was considerably more intense than those achieved in ferrogels that contain spherical magnetic microparticles. Therefore, the imbedding of rod-shaped magnetic particles in hydrogels allows controlling the mechanical properties in a wider range than in conventional ferrogels. This article is part of the theme issue 'Heterogeneous materials: metastable and non-ergodic internal structures'.
磁性凝胶（铁磁凝胶）是在纳米尺度上构建的多相体系，其包含分散在聚合物链三维网络中的磁性颗粒。在本工作中，磁性颗粒采用核壳结构合成，由被磁铁矿纳米颗粒覆盖的海泡石颗粒组成。这些复合颗粒呈高纵横比的棒状。所获得的海泡石 - 磁铁矿颗粒表现出足够高的磁化率和饱和磁化强度。对合成颗粒水悬浮液的磁流变（MR）特性以及MR效应强度进行了研究。通过藻酸盐分子吸附功能化的颗粒被嵌入藻酸盐水凝胶中以获得均匀的软材料。颗粒作为网络中的节点与聚合物链相连，并在很大程度上主导了材料的力学性能。在确定了铁磁凝胶的最佳组成后，在有无磁场的情况下测量了它们的粘弹性。结果指出，由粘土 - 磁铁矿颗粒提供的MR效应比含有球形磁性微粒的铁磁凝胶中实现的效应要强得多。因此，将棒状磁性颗粒嵌入水凝胶中能够比传统铁磁凝胶在更宽的范围内控制力学性能。本文是主题为“多相材料：亚稳态和非遍历内部结构”的一部分。
