Surface anchoring energy azimuthal

Fig. 5.9. Room temperature azimuthal surface anchoring energy coefficient of the 5CB liquid crystal on LPP PVCN substrate as a function of the LP UV irradiation time. The dashed line is guide to the eye.

Fig. 7.12. Azimuthal surface anchoring energy density as a function of separation between neighburing AFM lines.

The azimuthal LC surface anchoring energy was more than 10 " J/m, which is comparable with rubbed PI films. 

Here, the quantities JVo, Wa and Wp stand for the isotropic, azimuthal, and polar anchorings, respectively. The unit vectors % and point along the NP symmetry axis and perpendicular to it. W is integrated over the particle surface, neglecting its end parts. The resulting surface-anchoring Ifee-energy penalty is... 

For consistency we go back to the problem of the twisted cell discussed in Section 8.3.2, however, the director angles cp at the boundaries will be not constant but can be changed due to elastic and external torques. Let a nematic layer be confined by two plane surfaces with coordinates zj = —plane through angle cp (there is no tilt, the angle 9 = ti/2 everywhere, and the azimuthal anchoring energy is finite). 

In real SmC cells both Wf and W are finite. A finite azimuthal strength would create an additional surface torque trying to move the director from its angular positions at (p = 0 or

easy axis z, Fig.13.13. On the cone surface, the minimum anchoring energy W corresponds to director position at (p = 7t/2 and the minima of are at

anchoring energies with equal amplitudes W... 

When the liquid crystal director n is aligned along the direction specified by the polar angle G and azimuthal angle (p, the anisotropic part of the surface energy - referred to as the anchoring energy function - of the liquid crystal isfs=fs G,(p). When G = Gg and

[Pg.38]

The surface anchoring en gy is geno-ally expressed as a sum of independent terms gse(0) and gs4(< >) for the polar and azimuthal angles. A new approach in which the anchoring energy is written as a two-dimensional function 0,4) has been prqiosed thew ically and investigated. The coupling... 

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