1. A.M. Butlerov Chemistry Institute, Kazan Federal University, Kremlevskaya St. 18, 420008, Kazan, Russian Federation
2. Institute of Physics, Kazan Federal University, Kremlevskaya St. 18, 420008 Kazan, Russian Federation
3. Fachgebiet Technische Physik II/Polymerphysik,
Institute of Physics, Technische Universität Ilmenau, P.O. Box 100 565, 98684 Ilmenau, Germany