Color changing and lasing stretchable cholesteric films

Abstract

Polymer materials able to change reflective properties due to mechanical deformation fundamentally challenge the theory of soft materials and are important for a number of emerging applications. The most promising of those are chiral lasers. In this communication, we report novel cholesteric materials that display large color change from far red to blue and a shift of the position of the selective reflection band under uniaxial strain from near infrared to ultraviolet. Optical pumping of these materials which are doped with laser dyes, leads to lasing at the wavelengths controlled by strain within the emission interval of laser dyes of 80 nm.

Mechanism of colour changes in stretchable cholesteric films

“…As such, they display a much larger shift of the photonic band gap than cholesteric elastomers. Being doped with laser dyes, they may also display mechanically tunable optically pumped lasing; we have previously discussed this effect elsewhere [15].…”

Deformable Viscoelastic Cholesteric Films with Nanoparticles

“…The properties of polymer=MBBA system and dependence of viscosity on concentration of MBBA was studied in previous publications [1][2][3]. Here we mainly focus on the properties of composites filled with nanoparticles.…”

“…Highly viscous cholesteric liquid crystals (CLCs) sensitive to mechanical deformation, stretching, and shear were recently studied in [1][2][3][4]. In these materials high viscosity plays a crucial role in determining their peculiar mechanical response.…”

Distant mechanical sensors based on cholesteric liquid crystals

“…Recently, a gigantic shift of the SRB was achieved in highly viscous cholesteric liquid crystals placed between two flat silicone strips and stretched. [6][7][8][9] This system was shown also to exhibit lasing. 8,9 The major difference of such a system from cholesteric elastomers is the absence of crosslinks between molecules of cholesteric liquid crystals and the commercial availability of silicone monomers.…”

“…[6][7][8][9] This system was shown also to exhibit lasing. 8,9 The major difference of such a system from cholesteric elastomers is the absence of crosslinks between molecules of cholesteric liquid crystals and the commercial availability of silicone monomers. Moreover, a high viscosity of the CLC (5 Â 10 2 -5 Â 10 3 Pas) 6 leads to a low relaxation rate of cholesteric pitch, proportional to K cP ¼ 10 À7 À 10 À6 m/s (we used K ¼ 10 À11 N and helical pitch P ¼ 600 nm).…”