Modification of the twist angle in chiral nematic polymer films by photoisomerization of the chiral dopant

Abstract

Link to publication Citation for published version (APA):Witte, van de, P., Neuteboom, E. E., Brehmer, M., & Lub, J. (1999). Modification of the twist angle in chiral nematic polymer films by photoisomerization of the chiral dopant. Journal of Applied Physics, 85(11), 7517-7521. DOI: 10.1063/1.370548 General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. A method for the production of polarization sensitive recordings in liquid crystalline polymers is presented. The system is based on local modification of the twist angle of chiral nematic polymer films. The twist angle of the polymer film is varied by modifying the chemical structure of the chiral dopant. Here a photoisomerizable menthone derivative is used that has a fivefold difference in helical twisting power between the E and the Z isomer. The twist angle of the film can be varied between Ϫ90°and 0°by introducing a nonphotosensitive chiral dopant with opposite twisting sense. Complex pictures with gray scales can be recorded in the films with black and white contrasts higher than 20.

Synthesis and Properties of Photoisomerizable Derivatives of Isosorbide and Their Use in Cholesteric Filters

“…In layers containing small amounts of the isomerizable compound, the twist can be adjusted on a subpixel level. [35] Such twisted nematic films can find application as viewing-angle-improvement layers, as patterned retarders, or as polarizing glasses. [1] Reflective polarizers can be prepared by irradiating the monomeric film with an intensity gradient over the film thickness.…”

Predictions of molecular chirality and helical twisting powers: A theoretical study

“…They can be used in liquid crystal displays and in chiral polymer films to improve viewing angles in display applications. [1][2][3] In each case it is essential that a high degree of twist is imparted from just a small amount of chiral dopant, so as not to perturb other material properties, and, in some cases, because the dopant is sparingly soluble in the liquid crystal host. The production of new chiral dopant molecules can be a long and costly process, and the HTP of the molecule is unknown until it can be determined by experiment after it has been synthesized and purified.…”

Progress in computer simulations of liquid crystals

“…Chiral molecules with very high HTPs > 100 µm −1 have significant technological applications. They can be used in liquid crystal displays and in chiral polymer films to improve the viewing angle of a display [106][107][108]. There are also possible applications in polymer-stabilised blue phases [6], which may provide a new generation of devices: fast light modulators and tunable photonic crystals.…”