Issue 22, 2014

Viscoelasticity of nematic liquid crystals at a glance

Abstract

Polarised microscopy is shown to be a powerful alternative to light scattering for the determination of the viscoelasticity of aligned nematic liquid crystals. We perform experiments in a wide range of temperatures by using an adapted version of the recently introduced differential dynamic microscopy technique, which enables us to extract scattering information directly from the microscope images. A dynamic analysis of the images acquired in different geometries provides the splay, twist and bend viscoelastic ratios. A static analysis allows a successful determination of the bend elastic constant. All our results are in excellent agreement with those obtained with the far more time-consuming depolarised light scattering techniques. Remarkably, a noteworthy extension of the investigated temperature-range is observed, owing to the lower sensitivity of microscopy to multiple scattered light. Moreover, we show that the unique space-resolving capacities of our method enable us to investigate nematics in the presence of spatial disorder, where traditional light scattering fails. Our findings demonstrate that the proposed scattering-with-images approach provides a space-resolved probe of the local sample properties, applicable also to other optically anisotropic soft materials.

Graphical abstract: Viscoelasticity of nematic liquid crystals at a glance

Article information

Article type
Paper
Submitted
19 Jan 2014
Accepted
03 Mar 2014
First published
04 Mar 2014
This article is Open Access
Creative Commons BY license

Soft Matter, 2014,10, 3938-3949

Author version available

Viscoelasticity of nematic liquid crystals at a glance

F. Giavazzi, S. Crotti, A. Speciale, F. Serra, G. Zanchetta, V. Trappe, M. Buscaglia, T. Bellini and R. Cerbino, Soft Matter, 2014, 10, 3938 DOI: 10.1039/C4SM00145A

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