RESUMO
Nematic molecules confined in an asymmetric π cell and subjected to strong electric fields exhibit textural distortions involving nematic order variations, described by the Landau-de Gennes Q-tensor theory. We investigated the evolution of order variations as function of the applied electric pulse amplitude and of the nematic surface pretilt anchoring angles by implementing a Q-tensor model with a moving mesh finite element method. The proposed technique is able to clearly distinguish the bulk and the surface order reconstruction which occur in the cell.
Assuntos
Cristalização/métodos , Cristais Líquidos/química , Teste de Materiais/métodos , Modelos Químicos , Modelos Moleculares , Simulação por ComputadorRESUMO
Thermotropic nematic materials relax strong distortions by lowering the nematic order: the uniaxial symmetry is broken and is locally replaced by biaxial domains. We investigated the dynamics of the nematic order near a boundary surface of an asymmetric π-cell submitted to an external electric field, close to the electric order reconstruction threshold. An unexpected phenomenon is observed close, but below the threshold: the biaxial order spreads on the surface inducing a consequent bulk topological behaviour equivalent to the splay-bend fast transition allowed by order reconstruction at higher voltage.
