Effect of combined action of electric field and light on gliding of the easy axis in nematic liquid crystals

A new effect is described of the combined action of an electric field and light on the slow surface dynamics in a layer of nematic liquid crystal (NLC) contacted with a layer of dye pre‐treated by UV irradiation. Simultaneous application of a relatively weak “in‐plane” electric field and polarised light resulted in slow variation of the boundary orientation of the sample transmitted to the bulk of the layer. At the same time, the separate action of the two factors mentioned above did not produce any visible changes in the LC layer at the same intensity and time of application. After turning off both the electric field and light, extremely slow relaxation of the system to the initial state was observed. This effect depends on a number of control parameters (applied voltage, intensity of light, time of application, dose of a preliminary UV irradiation). The critical slowing down of this process (up to some weeks) via a proper choice of control parameters was established. The physical processes responsible for the combined effect were considered and applied to modify a previously proposed phenomenological model for the electrically induced slow azimuthal rotation of the easy axis of an NLC. The modified model was found to be in a qualitative agreement with the main experimental results.

[1]  C. Rosenblatt.  Nanostructured Surfaces: Scientific and Optical Device Applications , 2004 .

[2]  I Jánossy,et al.  Gliding of liquid crystals on soft polymer surfaces. , 2004, Physical review. E, Statistical, nonlinear, and soft matter physics.

[3]  M. Nobili,et al.  Surface reorientation dynamics of nematic liquid crystals , 1999 .

[4]  Ingo Dierking,et al.  Alignment Technologies and Applications of Liquid Crystal Devices. Liquid Crystals Book Series, Volume 5. By Kohki Takatoh, Masanori Sakamoto, Ray Hasegawa, Mitsushiro Koden, Nobuyuki Itoh and Masaki Hasegawa. , 2006 .

[5]  Masaki Hasegawa,et al.  Alignment Technology and Applications of Liquid Crystal Devices , 2005 .

[6]  D. Andrienko,et al.  Light-Induced Surface Sliding of the Nematic Director in Liquid Crystals , 1999 .

[7]  G. Barbero,et al.  Phenomenological model for the optically induced easy direction. , 2007, Physical review. E, Statistical, nonlinear, and soft matter physics.

[8]  Vladimir G. Chigrinov,et al.  Slow relaxation processes in nematic liquid crystals at weak surface anchoring , 2006 .

[9]  Vladimir G. Chigrinov,et al.  Liquid Crystal Devices: Physics and Applications , 1999 .

[10]  Measurements of the azimuthal anchoring energy at a polyimide-nematic interface with a new transmitted light method , 2004 .

[11]  V. Reshetnyak,et al.  Evolution of light-induced anchoring in dye-doped nematics: experiment and model. , 2006, Physical review. E, Statistical, nonlinear, and soft matter physics.

[12]  T. Rasing,et al.  Alignment of nematic liquid crystals on an electrically poled photopolymer film , 2001 .

[13]  Vladimir G. Chigrinov,et al.  Azimuthal surface gliding of a nematic liquid crystal , 1997 .

[14]  Magnetic Field Induced Director Reorientation in the Nematic Cell with Time-Dependent Anchoring Due to Adsorption/Desorption of LC Molecules , 2005 .

[15]  Hoi-Sing Kwok,et al.  Diffusion model of photoaligning in azo-dye layers. , 2004, Physical review. E, Statistical, nonlinear, and soft matter physics.