Rozynek Z, Wang B, Fossum J O, Knudsen K D
Department of Physics, NTNU, Høgskoleringen 5, NO-7491, Trondheim, Norway.
Eur Phys J E Soft Matter. 2012 Jan;35(1):9. doi: 10.1140/epje/i2012-12009-x. Epub 2012 Jan 31.
This report focuses on both the characterization of organically modified fluorohectorite (Fh) clay particles and their electric-field-induced alignment when suspended in a non-polar liquid (silicone oil). Thermal decomposition temperatures of the surfactant molecules adsorbed on the clay surfaces and those being intercalated between clay crystalline layers were measured by thermal gravimetric analysis (TGA). Zeta potential measurements confirmed the successful modification of the clay surfaces. Optical microscopy observations showed that the sedimentation of modified particles was much slower compared to that of the non-modified system. It was shown that organic modification has a significant effect on colloidal stability of the system, preventing particles from forming large aggregates when suspended in a non-polar liquid. There are also signs of a slight increase in overall alignment of the clay particles when exposed to in an electric field, with the nematic order parameter (S(2)) being higher for the organically modified particles, compared to that of the non-modified counterparts. This behaviour is mainly a result of the formation of smaller and more uniform aggregates, in contrast to the large aggregate structures formed by non-modified clay particles.
本报告重点关注有机改性氟锂蒙脱石（Fh）粘土颗粒的特性及其悬浮于非极性液体（硅油）中时的电场诱导排列。通过热重分析（TGA）测定吸附在粘土表面以及插层于粘土晶体层间的表面活性剂分子的热分解温度。ζ电位测量证实了粘土表面改性成功。光学显微镜观察表明，与未改性体系相比，改性颗粒的沉降要慢得多。结果表明，有机改性对体系的胶体稳定性有显著影响，可防止颗粒在悬浮于非极性液体时形成大的聚集体。当暴露于电场中时，粘土颗粒的整体排列也有轻微增加的迹象，与未改性颗粒相比，有机改性颗粒的向列序参数（S(2)）更高。这种行为主要是形成了更小且更均匀的聚集体的结果，这与未改性粘土颗粒形成的大聚集体结构形成对比。
