| Abstract
| - By irradiation with linearly polarized light at 366 nm, alignmentchange was generated inpolymer liquid crystals (MACB-ABn, n= 3, 6, and 11) with different spacer lengths of theazobenzeneunits but the same enthalpic stability of the liquid-crystalline phase.Polarized IR spectra revealed thatthe polymer main chain did not reorient while the mesogens were alignedperpendicular to the polarizationdirection of the writing light. The effect of the spacer length onalignment behavior was investigated bymeasuring the transmittance through the polymer liquid-crystal film andthe induced order parameters.Results show that alignment change is more difficult to be inducedin a polymer liquid crystal, having ashort spacer. The spacer length does not affect thetrans−cis photoisomerization andconsequent cis−trans thermal isomerization behavior. Therestriction of the polymer main chain on azobenzenemoietiesthrough the spacer affects the alignment efficiency of azobenzenemesogens and, therefore, affects thealignment behavior of the polymer liquid crystals.
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