Homeotropic and planar structures in liquid-crystalline polymer brushes

The ordering in polymer brushes formed by macromolecules with mesogenic gro ups in the main chain is investigated. The numerical method of self-consist ent field approximation was used. The existence of two different liquid cry stalline nematic states is shown: homeotropic (HLC) and planar (PLC) states . The free energy of the HLC state is always less than that of the PLC stat e. However, with the increase of energy of anisotropic interactions, (with decrease in temperature) our numerical procedure leads us to either one or another state depending on the grafting density. The results obtained show that both brush surfaces, play an essential role in establishing the concre te LC state structure. The grafting surface and the external surface force the planar order. (C) 2000 Elsevier Science Ltd. All rights reserved.