Security use of bilayer dichroic films made of liquid crystal polymer networks

Abstract

We report on bilayer dichroic dye-doped liquid crystal (BDLC) films for patternable color codes, which can be used in anti-counterfeiting applications such as security codes and, unlike the conventional single-layer LC color films, show unique color changes depending on the direction of the polarization of the incident light that passes through them. This is a facile way to enhance the security level of security codes. BDLC films are fabricated by laminating two single-layer LC polymer network films with crossed optical axes. We believe that BDLC films can be used as a new platform for a securityenhanced anti-counterfeiting code that can replace complex chiral materials or expensive plasmonic particles.

Patterned Hydrophobic Liquid Crystalline Fibers Fabricated from Defect Arrays of Reactive Mesogens via Electric Field Modulation

“…The polymerized RM forms an LC network (LCN), an anisotropic solid material that can be programmed with varied orientations, and the resulting LCN shows enhanced stability and programmed actuation. , In addition, a fibril polymer network is formed when less than 10 wt % RM is dispersed in a host LC and is subsequently polymerized, while a porous polymer film is formed when the concentration of the RM is higher than that . The polymerized network follows the orientation of the host LC and stabilizes the host LC, which is widely used in modulating optical properties. − After removing the host LC, a fibril network can be utilized for innovative applications such as internal director visualization, , directed cell growth, and templates for patterning other liquid crystals. , Since those performances depend on the morphology of polymer networks, changing the LC phase (ex. cholesteric, smectic, and blue phases) or utilizing external forces has been investigated to get the diverse shapes of polymers.…”