Jump to main content
Jump to site search


Thermal and electrical wavelength tuning of Bragg reflection with ultraviolet light absorbers in polymer-stabilized cholesteric liquid crystals

Author affiliations

Abstract

Autonomous stimulus-responsive polymer-stabilized cholesteric liquid crystals (PSCLCs) are promising materials for various applications. In this work, a PSCLC cell whose wavelength of selective reflection changes autonomously according to the temperature or can be controlled by applying an electric field was fabricated by using ultraviolet (UV) light absorbers. The UV light absorbers in the PSCLC cell are used not only for preventing the degradation of the substrate but also for stabilizing the polymeric network by converting the harmful UV radiation into harmless heat. To achieve the optimum conditions, different types of UV light absorbers were examined at various concentrations and UV light intensities. The results revealed that the benzophenone-type UV absorbers provide an extensive blue-shift tuning of the Bragg reflection in the PSCLC. By determining the molar extinction coefficient (ε) values, which provide a measure of UV light absorption at a given wavelength, at three important wavelengths—the maximum absorption wavelength (λmax) of the UV absorbers, λmax of the photoinitiator (345 nm), and the UV lamp wavelength (365 nm)—the UV light intensity gradient throughout the cell was defined. Reduction of the ε value indicates a sharp drop in the UV light intensity within a PSCLC cell. This phenomenon leads to the diffusion of reactive mesogens towards the UV lamp side of the cell to achieve a tight pitch gradient and extensive blue-shift tuning of the selective reflection.

Graphical abstract: Thermal and electrical wavelength tuning of Bragg reflection with ultraviolet light absorbers in polymer-stabilized cholesteric liquid crystals

Back to tab navigation

Supplementary files

Publication details

The article was received on 10 Sep 2018, accepted on 18 Oct 2018 and first published on 19 Oct 2018


Article type: Paper
DOI: 10.1039/C8TC04563A
Citation: J. Mater. Chem. C, 2018, Advance Article
  •   Request permissions

    Thermal and electrical wavelength tuning of Bragg reflection with ultraviolet light absorbers in polymer-stabilized cholesteric liquid crystals

    A. Ranjkesh and T. Yoon, J. Mater. Chem. C, 2018, Advance Article , DOI: 10.1039/C8TC04563A

Search articles by author

Spotlight

Advertisements