Mean field theory of nematic order for grafted rods

We consider rod-like polymers which are grafted on a flat surface, such that the grafting sites are mobile. A liquid interface supporting a monolayer of amphiphilic copolymers consisting of rod-like and coil-like parts may realize this model. Using the Onsager approach we find that alignment increases with surface concentration in a continuous fashion. We present diagrams of surface pressure and of nematic order parameter vs surface concentration.