Computer simulations and theory of polymer tethered nanorods: the role of flexible chains in influencing mesophase stability

The mesophase behaviour of a polymer tethered nanorod is assessed by means of statistical mechanical theory and molecular dynamics simulation. A model system is considered in which a colloidal nanorod is tethered to a flexible polymer chain, which is able to form an ideal'' polymer coil in solution. As chain length increases, it is shown that the stability of the nematic phase first increases and then decreases, while smectic stability is continually enhanced. For a sufficiently long chain, the nematic phase is suppressed altogether and an isotropic-smectic phase transition is seen. It is shown by statistical mechanical theory that the major influence of the chain can be understood in terms of the radius of the polymer coil relative to the width of the nanorod. This provides the possibility of using good or poor solvent conditions to tune the mesophase stability of a colloidal system of nanorods, simply by changing the influence of a tethered polymer chain.