GRAFTED RODS - A TILTING PHASE-TRANSITION

A tilting phase transition is predicted for systems comprising rod lik e molecules which are irreversibly grafted to a flat surface, so that the non interacting rods are perpendicularly oriented. The transition is controlled by the grafting density rho. It occurs as rho increases as a result of the interplay between two energies. Tilt is favoured by the van der Waals attraction between the rods. It is opposed by the b ending elasticity of the grafting functionality. The role of temperatu re is discussed, and the tilting mechanism is compared to other tiltin g transitions reported in the literature.