A model for surface-relief formation in azobenzene polymers

Theory of light-induced deformations in azobenzene polymers: structure-property relationship

“…[5,26,27] It has been shown by Bublitz et al [5] that different types of azobenzene side-chain polyesters undergo an opposite change of shape under illumination with linearly polarized light. This result is in agreement with the observation that the phase of the SRGs, relative to that of the optical grating, strongly depends on the chemical architecture of the particular azobenzene polymer.…”

“…[29] Sensitivity of photomechanical behavior (stretching or uniaxial compression) to the chemical structure of azobenzene polymers was found also experimentally. [5] 3. Non-monotonical behavior takes place when 54,7°<α * <A(β * ), i.e C1>0 and C2<0 (area 3 in Figure 3).…”

“…1c), which are widely used for preparing azobenzene polymers. [3][4][5] Therefore, in the present paper we consider the properties of oligomers with symmetric distribution of chromophores around the main chains, namely, W(α,β)=W(α,-β) and W(α,β)=W (180°-α,β). Important examples are molecules with chromophores which are fixed at equiprobable angles β=±β * and α=α * , 180°-α * .…”

“…As a result, a polymer changes its shape with respect to the polarization vector E of the linearly polarized light (contraction or expansion depending on the chemical structure). [5] Appearing photo-induced stress is so large that the light irradiation of the intensity I p ~ 1 W/cm 2 (which is usually used in experiments) is able to deform an amorphous polymer being even in the glassy state. [6,7] This feature is used in the procedure of inscription of surface relief gratings onto thin azobenzene polymer films.…”

Photosensitive response of azobenzene containing films towards pure intensity or polarization interference patterns

“…Because of this multi-variability, many aspects of the SRG formation phenomenon are not yet well understood, although several theoretical attempts have been made considering the molecular mass transport due to the local gradients in pressure, in the molecular reorientation, and the free volume. [15][16][17][18][19][20][21][22] Experimentally, the SRG formation and the associated relaxation phenomenon is usually studied using the diffraction efficiency method with a linearly or circularly polarized probe beam. [23][24][25][26][27] The diffraction efficiency method probes induced birefringence in the optically anisotropic media averaged over a large area.…”