@article{RyabchunRaguzinStumpeetal.2016,
  author    = {Ryabchun, Alexander and Raguzin, Ivan and Stumpe, Joachim and Shibaev, Valery and Bobrovsky, Alexey},
  title     = {Cholesteric Polymer Scaffolds Filled with Azobenzene-Containing Nematic Mixture with Phototunable Optical Properties},
  series = {Scientific reports},
  volume    = {8},
  journal   = {Scientific reports},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1944-8244},
  doi       = {10.1021/acsami.6b09642},
  pages     = {27227 -- 27235},
  year      = {2016},
  abstract  = {The past two decades witnessed tremendous progress in the field of creation of different types of responsive materials. Cholesteric polymer networks present a very promising class of smart materials due to the combination of the unique optical properties of cholesteric mesophase and high mechanical properties of polymer networks. In the present work we demonstrate the possibility of fast and reversible photocontrol of the optical properties of cholesteric polymer networks. Several cholesteric photopolymerizable mixtures are prepared, and porous cholesteric network films with different helix pitches are produced by polymerization of these mixtures. An effective and simple method of the introduction of photochromic azobenzene-containing nematic mixture capable of isothermal photoinducing the nematic isotropic phase transition into the porous polymer matrix is developed, It is found that cross-linking density and degree of polymer network filling with a photochromic nematic mixture strongly influence the photo-optical behavior of the obtained composite films. In particular, the densely cross-linked films are characterized by a decrease in selective light reflection bandwidth, whereas weakly cross-linked systems display two processes: the shift of selective light reflection peak and decrease of its width. It is noteworthy that the obtained cholesteric materials are shown to be very promising for the variety applications in optoelectronics and photonics.},
  language  = {en}
}
@article{RyabchunSakhnoStumpeetal.2017,
  author    = {Ryabchun, Alexander and Sakhno, Oksana and Stumpe, Joachim and Bobrovsky, Alexey},
  title     = {Full-Polymer Cholesteric Composites for Transmission and Reflection Holographic Gratings},
  series = {Advanced optical materials},
  volume    = {5},
  journal   = {Advanced optical materials},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {2195-1071},
  doi       = {10.1002/adom.201700314},
  pages     = {376 -- 379},
  year      = {2017},
  abstract  = {A new type of self-organized materials based on cholesteric networks filled with photoactive side-chain copolymer is being developed. Supramolecular helical structure of cholesteric polymer network resulting in the selective reflection is used as a photonic scaffold. Photochromic azobenzene-containing nematic copolymer is embedded in cholesteric scaffold and utilized as a photoactive media for optical pattering. 1D and 2D transmission diffraction gratings are successfully recorded in composite films by holographic technique. For the first time the possibility to create selective reflection gratings in cholesteric material mimicking the natural optical properties of cholesteric mesophase is demonstrated. That enables the coexistence of two selective gratings, where one has an intrinsic cholesteric periodic helical structure and the other is a holographic grating generated in photochromic polymer. The full-polymer composites provide high light-induced optical anisotropy due to effective photo-orientation of side-chain fragments of the azobenzene-containing liquid crystalline polymer, and prevent the degradation of the helical superstructure maintaining all optical properties of cholesteric mesophase. The proposed class of optical materials could be easily applied to a broad range of polymeric materials with specific functionality. The versatility of the adjustment and material preprogramming combined with high optical performance makes these materials a highly promising candidate for modern optical and photonic applications.},
  language  = {en}
}