Тип публикации: статья из журнала
Год издания: 2001
Ключевые слова: Additives, Elastic moduli, Liquid crystals, Thermal effects, Thermodynamics, Polar angle orientation, Light reflection
Аннотация: The spectra of the selective reflection of light in encapsulated cholesterics (EC) containing pyrimidine additives (PA) have been measured over all the temperature range of the mesophase existence which have showed that the pyrimidine additives initiate the second reflection region. The second reflection region merges with the first one with the temperature increasing. To explain these data, the thermodynamically equilibrium and spatially inhomogeneous states of EC have been considered under the action of PA. Additives have been simulated by the near-surface orientation potential. The problem has been considered both analytically for a rectangular form of the additive potential in the single-constant approximation, and numerically for an arbitrary potential form and different elastic constants. An analogous problem has been considered for film cholesterics. The existence of two spatial regions of the capsule and film has been shown. The solution of the problem for the internal region is close to the solution for the pure capsule with the normal polar angle orientation. The orientation of the director field in the external region significantly differs from the normal one. Two characteristic helix steps appear which are determined by the correlation between moduli of elasticity K2 and K3. These results describe the existence of two regions of the selective reflection of light and the temperature behavior of helix steps of encapsulated cholesterics containing pyrimidine additives.
Журнал: Surface Investigation X-Ray, Synchrotron and Neutron Techniques
Выпуск журнала: Vol. 16, Is. 10
Номера страниц: 1639-1651