Forschugszentrum Jülich, Institute of Complex Systems ICS-3, Jülich, Germany.
Electron Microscopy for Materials Research (EMAT), University of Antwerp, Belgium.
Soft Matter. 2016 Oct 19;12(41):8485-8494. doi: 10.1039/c6sm01376g.
In this article we report on the synthesis and characterization of a system of colloidal spheres suspended in an aqueous solvent which can be refractive index-matched, thus allowing for investigations of the particle near-wall dynamics by evanescent wave dynamic light scattering at concentrations up to the isotropic to ordered transition and beyond. The particles are synthesized by copolymerization of a fluorinated acrylic ester monomer with a polyethylene-glycol (PEG) oligomer by surfactant free emulsion polymerization. Static and dynamic light scattering experiments in combination with cryo transmission electron microscopy reveal that the particles have a core shell structure with a significant enrichment of the PEG chains on the particles surface. In index-matching DMSO/water suspensions the particles arrange in an ordered phase at volume fraction above 7%, if no additional electrolyte is present. The near-wall dynamics at low volume fraction are quantitatively described by the combination of electrostatic repulsion and hydrodynamic interaction between the particles and the wall. At volume fractions close to the isotropic to ordered transition, the near-wall dynamics are more complex and qualitatively reminiscent of the behaviour which was observed in hard sphere suspensions at high concentrations.
本文报道了一种胶体球悬浮在水溶剂中的体系的合成和表征，该体系可与折射率相匹配，从而允许在各向同性到有序转变及以上浓度下通过消逝波动态光散射研究粒子近壁动力学。这些粒子是通过氟丙烯酸酯单体与聚乙二醇（PEG）低聚物的无表面活性剂乳液聚合共聚合成的。静态和动态光散射实验结合低温透射电子显微镜揭示了粒子具有核壳结构，粒子表面上PEG 链的富集程度很高。在折射率匹配的 DMSO/水悬浮液中，如果不存在额外的电解质，粒子在体积分数高于 7%时会排列成有序相。在低体积分数下，粒子与壁之间的静电排斥和流体动力相互作用定量地描述了近壁动力学。在接近各向同性到有序转变的体积分数下，近壁动力学更加复杂，定性上类似于在高浓度下硬球悬浮液中观察到的行为。
