AZIMUTHAL ANCHORING TRANSITION OF NEMATIC LIQUID-CRYSTALS ON SELF-ASSEMBLED MONOLAYERS FORMED FROM ODD AND EVEN ALKANETHIOLS

A first order orientation transition, characterized by a 90 degrees az imuthal rotation of the surface easy direction, is reported for nemati c liquid crystals (NLCs) anchored on self-assembled monolayers (SAMs). The SAMs are formed from alkanethiols [CH3(CH2)(n-1)SH; 5 less than o r equal to n less than or equal to 16] on obliquely deposited films of gold. The anchoring of the NLC is uniform and planar; the azimuthal o rientation of the nematic director is, however, perpendicular to the d irection of deposition of gold on SAMs formed from alkanethiols with o dd chain lengths (n = odd) and is parallel to the direction of deposit ion of gold on SAMs formed from alkanethiols with even (n = even) chai n lengths.