Al-Lawati Z.H.,Molecular and Nanoscale Physics |
Alkhairalla B.,Molecular and Nanoscale Physics |
Bramble J.P.,Molecular and Nanoscale Physics |
Henderson J.R.,Molecular and Nanoscale Physics |
And 2 more authors.
Journal of Physical Chemistry C | Year: 2012
The alignment of the lyotropic discotic liquid crystal 2,3,6,7,10,11-hexa- (1,4,7-trioxaoctyl)-triphenylene (TP6EO2M) on -CO 2H and -CH 3 self-assembled monolayers (SAMs) has been investigated in order to determine whether the surface free energy could be used to control anchoring in such a system. Irrespective of the SAMs used we found that the alignment tends to be with the director in the plane of the surface. To understand why the different SAM types produce the same bulk behavior we considered the adsorption of TP6EO2M from dilute solutions. In the case of -CH 3 surfaces we found the first adsorbed DLC layer lies with its triphenylene core close to the hydrophobic SAM, leaving the hydrophilic chains extending from the surface. For the -CO 2H surfaces the first DLC layer is believed to be edge-on again, leading to hydrophilic chains extending away from the surface. These adsorbed DLC layers give rise to planar alignment of the bulk nematic and columnar phases. © 2012 American Chemical Society.