Roger Stéphane, Sang Yan Yip Cheung, Bee Agnès, Perzynski Régine, Di Meglio Jean Marc, Ponton Alain
UPMC Univ Paris 06, CNRS, Lab. PHENIX, Case 51, Sorbonne Universités, 4 place Jussieu, F-75005, Paris, France.
Eur Phys J E Soft Matter. 2015 Aug;38(8):88. doi: 10.1140/epje/i2015-15088-1. Epub 2015 Aug 14.
We present a structural and a multi-scale rheophysical investigation of magneto-sensitive materials based on biopolymers, namely aqueous solutions of sodium alginate incorporating magnetic maghemite nanoparticles, functionalized with adsorbed negative citrate ions. The large alginate ionic strength impacts the structure and the rheology of these nanocomposites in zero magnetic field. In given physico-chemical conditions, the system is fluid and homogeneous on macroscopic scales while it is diphasic on microscopic ones, containing micro-droplets coming from the demixion of the system. These micro-droplets are liquid and deformable under magnetic field. Their under-field elongation and their zero-field relaxation are directly observed by optical microscopy to determine their interfacial tension, their magnetic susceptibility and their internal viscosity. A structural analysis of the solutions of alginate chains and of the phase-separated mixtures of alginate and nanoparticles by Small Angle Scattering completes the local description of the system.
我们对基于生物聚合物的磁敏材料进行了结构和多尺度流变物理研究，该材料为掺入磁性磁赤铁矿纳米颗粒的海藻酸钠水溶液，这些纳米颗粒被吸附的柠檬酸根负离子官能化。在零磁场中，海藻酸钠的高离子强度会影响这些纳米复合材料的结构和流变学。在给定的物理化学条件下，该系统在宏观尺度上是流体且均匀的，而在微观尺度上是两相的，包含来自系统 demixion 的微滴。这些微滴是液体，在磁场作用下可变形。通过光学显微镜直接观察它们在磁场下的伸长和在零场下的弛豫，以确定它们的界面张力、磁化率和内部粘度。通过小角散射对海藻酸链溶液以及海藻酸钠和纳米颗粒的相分离混合物进行结构分析，完善了对该系统的局部描述。
