Osmotic-Pressure-Induced Nematic Ordering in Suspensions of Laponite and Carboxy Methyl Cellulose
- 11 October 2020
- journal article
- research article
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry B
- Vol. 124 (42), 9475-9481
- https://doi.org/10.1021/acs.jpcb.0c06674
Abstract
Laponite is a synthetic clay that is known to form gels in aqueous suspensions at low concentrations (0.01 g/cm3). Although it is expected to form lyotropic liquid crystals, such phases usually do not form, as a consequence of laponite’s tendency to form gels at concentrations below the threshold for liquid crystal formation. Here we show that macroscopic, birefringent phases of laponite can be prepared through osmotic compression of a laponite solution by an aqueous solution of carboxy methyl cellulose (CMC). We present polarization imaging studies showing how the initially dilute, isotropic laponite phase shrinks while developing typical birefringence colors between crossed polarizers. Using the Michel-Lévy interference charts, we were able to extract the refractive index and orientation of the laponite nanodisks in the compressed region. Our observations allow us to propose a tentative state diagram, indicating the concentration regions for which we obtain optically anisotropic gels.Keywords
Funding Information
- Royal Society
- University of Cambridge
This publication has 27 references indexed in Scilit:
- Universal Sol State Behavior and Gelation Kinetics in Mixed Clay DispersionsLangmuir, 2011
- A fresh look at the Laponite phase diagramSoft Matter, 2011
- Liquid-Crystalline Nematic Phase in Aqueous Suspensions of a Disk-Shaped Natural Beidellite ClayThe Journal of Physical Chemistry B, 2009
- High-bandwidth viscoelastic properties of aging colloidal glasses and gelsPhysical Review E, 2008
- Optical anisotropy in polymer–clay nanocomposite hydrogel and its change on uniaxial deformationJournal of Materials Chemistry, 2007
- Fluctuation-Dissipation Theorem in an Aging Colloidal GlassPhysical Review Letters, 2007
- Liquid–crystalline aqueous clay suspensionsProceedings of the National Academy of Sciences of the United States of America, 2006
- Phase Diagrams of Wyoming Na-Montmorillonite Clay. Influence of Particle AnisotropyLangmuir, 2004
- Behaviour of a synthetic clay in pigment dispersionsRheologica Acta, 1965
- The form birefringence of macromoleculesActa Crystallographica, 1953