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 azimuthal rotation of the surface easy direction, is reported for nematic liquid crystals (NLCs) anchored on self-assembled monolayers (SAMs). The SAMs are formed from alkanethiols [CH3(CH2)(n-1)SH; 5 less than or 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 orientation of the nematic director is, however, perpendicular to the direction of deposition of gold on SAMs formed from alkanethiols with odd chain lengths (n = odd) and is parallel to the direction of deposition of gold on SAMs formed from alkanethiols with even (n = even) chain lengths.