Quenched degrees of freedom in symmetric diblock copolymer thin films

We study the effect of monomer immobilization (quenching) on the orientation of the lamellae in symmetric diblock copolymer thin films with neutrally wetting surfaces. A small fraction of the monomers immediately next to the solid substrate is presumed to be quenched. In both the weak segregation limit and the strong segregation limit, quenching favors the lamellae orienting perpendicular to the film. Quenching inhibits the order-disorder transition twice as much for the parallel orientation as for the perpendicular.