Photoswitchable chevron topographies of glassy nematic coatings

We report a strategy to create photoswitchable chevron topographies via buckling of glassy nematic coatings with zigzag director alignments on soft elastic substrates. The idea is confirmed by numerical simulations where the nonlinear deformation of the coating is modeled by the Foppl-von Karman plate theory. It is remarkable that the inclination angle of the chevron pattern may deviate significantly from the director orientation and depends on the period of director alignment. Our quantitative analysis shows that the phenomena are caused by in-plane shear stress which alters the direction of maximum principal stress in the coating and decreases monotonically with decreasing period of the director distribution.