title: Controlling the assembly of CdS nanorods via solvent and acidity.
abstract: We report control over the phase behavior of CdS nanorods via the solvent and acidity. CdS nanorods were synthesized using alkane phosphonic acid ligands, which were replaced after synthesis by a series of aromatic ligands. Change of ligand enabled us to cast films from different solvents. By replacing toluene with ethanol or water the rod-rod interactions dominate over rod-substrate interactions, thereby favoring simple hexagonal ordering (2D). When dispersed in water, a net electrostatic charge on the nanorods could be induced by deprotonating the ligands at high pH. This net charge favors 2D nematic ordering over homeotropic ordering of the nanorods on a substrate. A calculation of the van der Waals and electrostatic interactions is presented that explains the observed influence of solvent and pH.
authors.affiliation: Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, UK.
authors.forename: L J A
authors.initials: LJ
authors.lastname: Koster
authors.forename: S
authors.initials: S
authors.lastname: Khodabakhsh
authors.forename: N C
authors.initials: NC
authors.lastname: Greenham