Liquid crystal phase behavior of sterically-stabilized goethite

The liquid crystalline phase behavior of sterically-stabilized goethite particles in toluene was studied using small-angle X-ray scattering. The results were compared with those from charged particles in water, with and without magnetic field: similarly rich phase behavior was found. Furthermore, the special magnetic properties were retained after coating the particles with amino-functionalized polyisobutylene chains. A remarkable difference between the aqueous and toluene samples is the latter’s tendency to form gels. Smaller domains of the different liquid crystalline phases were observed and the columnar phase does not fully develop, furthermore a higher field is needed to align the full sample.

In a magnetic field, liquid crystal phases of polymer coated goethite particles in toluene are compared to that of charged goethite particles in water. Similarly rich phase behavior was found, but a remarkable difference is the strong tendency to form gels in polymer coated systems.Figure optionsDownload high-quality image (102 K)Download as PowerPoint slideResearch highlights
► Sterically-stabilized goethite particles in toluene show similarly rich liquid crystal phase behavior as charged goethite particles in water, on which much work has already been done.
► The special magnetic properties – reorientation from parallel to perpendicular to the field going from small to large fields – were retained after coating the particles with amino-functionalized polyisobutylene chains.
► A remarkable difference between the aqueous and toluene samples is the latter’s tendency to form gels.