Static and Dynamic Control of Fingerprint Landscapes of Liquid Crystal Network Coatings

Wei Feng, Dirk J. Broer, Lucie Grebikova, Clemens Padberg, Julius G. Vancso, Danqing Liu*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Surface topography variations of liquid crystal networks in their functional coatings provide unique properties in these systems. Chiral-nematic polymer coatings self-organize in a fingerprint texture with the molecular helices parallel to the substrate with alternating domains of molecular units with parallel and perpendicular director orientation as controlled by the concentration of a reactive chiral additive. Driven by surface-tension differences and altered by anisotropic polymerization shrinkage, the coating may form hills and valleys hundreds of nanometers in size with different molecular alignment. The director orientation in the corrugations could be controlled by monomer diffusion during polymerization. Polymerization in the presence of a dichroic dye gives topographic elevations in which the molecules are oriented along the normal. Polymerization by means of a dichroic photoinitiator gives topographic elevations in which the molecules align parallel to the surface. By balancing the monomer diffusion and anisotropic polymerization shrinkage, relatively flat surfaces are also achieved. The different surfaces exhibit distinct topographical deformations when subjected to external stimuli, such as an AC electric field. This method can be universally extended to LC polymers with other alignment configurations.

Original languageEnglish
Pages (from-to)5265-5273
Number of pages9
JournalACS Applied Materials and Interfaces
Volume12
Issue number5
Early online date6 Sep 2019
DOIs
Publication statusPublished - 5 Feb 2020

Keywords

  • UT-Hybrid-D
  • electric field
  • fingerprint
  • liquid crystal networks
  • surface topography
  • dichroic molecules

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