Chiral photochromic liquid crystalline polymers for holography applications

Existence of Two Different Isotropic Phases as a Reason for Bistable Phase Behavior of an LC Side‐Chain Polymethacrylate

“…[8] The unique optical properties of the P8 Ã NN films in TGB phase make it promising for applications such as photorecording media. [9,10] A schematic sketch of the short pitch TGB phase is given in Supporting Information ( Figure S1), while its structure and properties are reported in detail elsewhere. [8] We should note that both the short pitch TGB phase and Sm A phase are kinetically stable and cannot be transformed to each other without heating above the phase transition point, T sm .…”

Effect of Molecular Weight on Photoinduced Birefringence in a Chiral Liquid Crystalline Azodye Polymer

“…The polymer is characterized by a high efficiency of phase grating recording15 and by ‘bistable phase behavior’, i.e., the formation of two different mesomorphic states at ambient temperature depending on the previous rate of cooling 16…”

“…Such an ‘isotropic smectic’ phase should be, therefore, especially applicable as a photorecording media. A short pitch TGB A* structure is suggested for the ‘transparent’ mesophase of P8*NN16 by analogy with similar colorless chiral polymers, where the presence of a helical superstructure with an extra short pitch of about 250 nm has been justified by optical rotatory dispersion (ORD) and selective UV reflection 15,17. In this work, all the measurements are performed with films in the latter (transparent TGB‐like) mesophase.…”

Bistable Phase Behavior and Kinetics of Nonisothermal Mesophase Formation in a Chiral Side Chain Polymethacrylate

“…Thus, e.g., a phase holographic gitter written in a P8*NN film by circularly polarized laser beam shows diffraction efficiency as high as 35% and more. 21 The mesophase of the polymer, as formed by spontaneous cooling from above the phase transition, appears optically isotropic and transparent for the wavelength range λ > 500 nm but possesses a hidden layered (smectic) structure. On the other hand, an ambiguous mesomorphism has been observed for P8*NN so that its optical appearance as an LC glass depends critically on cooling rate.…”

“…The recently synthesized polymer is distinguished for high photooptical response being a promising holographic media. Thus, e.g., a phase holographic gitter written in a P8*NN film by circularly polarized laser beam shows diffraction efficiency as high as 35% and more …”