Surface induced twist in nematic and chiral nematic liquid crystals: stick-slip-like and constrained motion

Autor(es)

de Souza, R. F. ^[1] ; Lenzi, E. K. ^[2] ; de Souza, R. T. ^[3] ; Evangelista, L. R. ^[1] ; Li, Q. ^{[4, 5]} ; Zola, R. S. ^[3]

Afiliação do(s) autor(es)

^[1] Univ Estadual Maringa, Dept Fis, Ave Colombo 5790, BR-87020900 Maringa, Parana - Brazil

^[2] Univ Estadual Ponta Grossa, Dept Fis, BR-87030900 Ponta Grossa, PR - Brazil

^[3] Univ Tecnol Fed Parana, Dept Fis, Rua Marcilio Dias 635, BR-86812460 Apucarana, Parana - Brazil

^[4] Kent State Univ, Inst Liquid Crystal, Kent, OH 44242 - USA

^[5] Kent State Univ, Chem Phys Interdisciplinary Program, Kent, OH 44242 - USA

• Tipo de documento: Artigo Científico
• Fonte: SOFT MATTER; v. 14, n. 11, p. 2084-2093, MAR 21 2018.
• Citações Web of Science: 6

Resumo

Surface driven pattern formation is an intriguing phenomenon in the liquid crystal field. Owing to its ability to transmit torque, one can generate different patterns by propagating distortions on the optical wavelength scale in the sample from the surface. Here, we theoretically investigate (from the elasticity point of view) twist deformations induced by a rotating easy axis at one surface, by considering the anchoring energy and surface viscosity of nematic and chiral nematic samples. The model is solved analytically in the limit of strong anchoring and numerically for a low anchoring strength situation. Such rotation could be induced, in principle, by light-controlling the orientation of an azobenzene monolayer coated at one of the glass substrates or by an in-plane rotating field. We discuss the role of the surface parameters and the different distortions, and calculate light transmission using the Jones method. Three different regimes are identified: free twist, stick-slip twist, and constrained twist. The results obtained here may be relevant for liquid crystal active waveplates and for determining surface viscosity and the azimuthal anchoring energy. (AU)

• Processo FAPESP: 14/50983-3 - INCT 2014: fluidos complexos
• Beneficiário: Antonio Martins Figueiredo Neto
• Linha de fomento: Auxílio à Pesquisa - Temático