PHASE-TRANSITIONS IN POLYMER BRUSHES

Liquid crystalline ordering in planar polymer brushes is investigated theoretically by numerical calculations within a self-consistent field approximation. The brushes are formed by macromolecules with mesogeni c groups in main chain and immersed in a solvent. Existence of a micro phase segregated brush (MSB) regime with a collapsed orientationally o rdered intrinsic sublayer and a swollen external sublayer is shown. At small grafting density, the transition from a conventional brush stat e to the microphase segregated state is a jump-wise first order phase transition for a finite chain length (A?. The magnitudes of the jumps in the average characteristics of the brush tend to zero in the limit N --> infinity since this transition occurs only in a vanishingly smal l part (proportional to N-1/2) Of the brush. High compressibility of M SB brush is demonstrated. The origin of phase transition in planar bru shes is discussed.