Polymer brushes uniform surface response

Scheme 1. Uniform surface response of mixed polymer brushes.

Scheme 2. Non-uniform surface response of segregated polymer brushes.

Twist relaxation of splay and bend is a general phenomenon in materials with small K2. Chiral structures can occur in defective nematic samples even when there is no azimuthal anchoring at all. Twisted brushes observed by Press and Arrott in textures of lens-shaped nematic droplets floating on the water surface are one example [15]. Another well-known illustration of twist relaxation is the periodic pattern of stripes that occur in the geometry of splay Frederiks transition in polymer nematics with a small (less than 0.33) ratio K2/K [16]. A field applied normally to the planar nematic cell causes stripe structures composed mostly of twist rather than the uniform splay response observed in regular materials. 

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