Chromonic Liquid Crystals – Oleg Lavrentovich

Date: Thu. November 1st, 2007, 4:15 pm-5:15 pm
Location: Rockefeller 301

Lyotropic chromonic liquid crystals (LCLCs) are formed by molecules with rigid polyaromatic cores and ionic groups at the periphery that form aggregates while in water [1]. Light scattering experiments demonstrate that the isotropic-to-nematic pretransitional behavior does not follow the classic Landau – de Gennes model, as the length of aggregates changes with temperature [2]. Most of the LCLCs are not toxic to the biological cells [3] and can be used as an amplifying medium in real-time biosensors [4]. The detector is based on the principle that the immune aggregates growing in the LCLC bulk trigger director distortions. Self-assembly of LCLC molecules into oriented structures allows one to use them in various structured films with potential applications as polarizers and optical compensators. For example, layer-by-layer electrostatic deposition produces monomolecular layers and stacks of layers of LCLC with long-range in-plane orientational order which sets them apart from the standard Langmuir-Blodgett films [5]. We discuss how the properties of the LCLCs are changed when the molecular interactions within the aggregates and between the aggregates are altered by different additives, both charged (such as multivalent ions) and neutral.

1. J. Lydon, Curr. Opin. Colloid Interface Sci. 3, 458 (1998); 8, 480 (2004).
2. Yu. A. Nastishin et al., Phys. Rev. E 70, 051706 (2004); Phys. Rev. E 72, 041711 (2005).
3. C.J. Woolverton et al., Liq. Cryst. 32, 417 (2005)
4. S.V. Shiyanovskii et al. Phys. Rev. E 71, 020702(R) (2005)
5. T. Schneider et al., Langmuir 16, 5227 (2000), 21, 2300 (2005)