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The aim of this review is to present the actual status of development in adaptive solar control by use of thermotropic and organic thermochromic materials. Such materials are suitable for application in smart windows. In detail polymer blends, hydrogels, resins, and thermoplastic films with a reversible temperature-dependent switching behavior are described. A comparative evaluation of the concepts for these energy efficient materials is given as well. Furthermore, the change of strategy from ordinary shadow systems to intrinsic solar energy reflection materials based on phase transition components and a first remark about their realization is reported. Own current results concerning extruded films and high thermally stable casting resins with thermotropic properties make a significant contribution to this field.

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Upon irradiation with linearly polarized light a photoorientation process occurs in spincoated films of polymethacrylates with 4-hexyloxyazobenzene side groups containing para methoxy and trifluoromethoxy tail groups. It results in the induction of an oblate orientational distribution perpendicular to the electric field vector causing an optical in-plane anisotropy up to an order parameter of about 0.52. The annealing of the photoreoriented films above T g results in a prolate homeotropic alignment in the center of the irradiated spot up to a degree of order of 0.78, whereas an amplification of the photoinduced in-plane anisotropy is observed in the interim region to the nonirradiated film area. The development of the in-plane and the out-of-plane components is compared for the photoorientation and the subsequent photoreorientation process in this series of polymers. In both cases, the photogenerated order in the glassy state acts as an initializing force for the thermotropic self-organization resulting in a significant narrowing of an uniaxial orientational distribution. Thus, a photoinduced "command" effect in the bulk of the LC polymers is caused by the combination of both principles of orderingsthe photoorientation and the liquid crystallinity.

Amorphous, optically isotropic films of photochromic liquid crystalline copolymers have been prepared and irradiated with linearly polarized light. In this way high values of dichroism and birefringence have been induced.