Orientational Order in Clay Gels

抄録

This article describes the nematic-like orientational order of exfoliated platelets in concentrated smectite clay gels. At concentrations larger than a few percent (w/w), clay gels are strongly birefringent, which is usually associated with nematic liquid-crystalline ordering. This means that the clay platelets tend to align parallel to each other in a cooperative way. Indeed, very oriented samples can easily be prepared and their SAXS patterns are strongly anisotropic, resulting in nematic order parameters of S-0.55 quite comparable to those of common organic liquid crystals used for display applications. Even though the sol/gel transition occurs at concentrations lower than the isotropic/nematic one, nematic ordering appears in concentrated clay gels and it must be considered in most practical situations.