image: a, Synthesis process of the oligomer. b, Filaments can be drawn by pulling a needle out of an oligomer solution droplet (schematically illustrated in inset). The red arrow connects the droplet to its components listed in (a). c–e, Schematics (not to scale) illustrating the filament extraction from a syringe containing the oligomer solutioon (as indicated by the red arrow) onto the rotating mandrel (c) and the filament shape immediately after deposition (d) and after anisotropic deswelling (e). f,g, Idealized schematics (not to scale) illustrating the flow-aligned paranematic state at stage d and the ideal cholesteric structure with vertical helix promoted by anisotropic deswelling at stage e, respectively. The grey arrows relate identical features shown with different views in different panels, and the colour bar in the lower left corner of f indicates the director orientation with respect to the long axis of the filament. h, SEM image of CLCE fibre obtained by polymerizing the filament of the precursor liquid. i–k, Crossed-polarizer microscopy (i) and SEM images (j and k) of a 5-μm-thick cross-sectional slice of the fibre embedded in NOA glue (isotropic). Scale bar in k is 10 μm. BHT, butylated hydroxy toluene; TEA, triethylamine. view more
Credit: Geng, Y., Kizhakidathazhath, R. & Lagerwall, J.P.F. Robust cholesteric liquid crystal elastomer fibres for mechanochromic textiles. Nat. Mater. (2022). https://doi.org/10.1038/s41563-022-01355-6
When we think about clothing, we usually think of it as something we wear to cover our body, convey our style and protect us from the environment. What if the cloth changes its visual appearance when you stretch your hand?... such mechanoresponsive material has enormous potential in a large range of transformative applications in the beauty and health industry.
Cholesteric Liquid Crystal Elastomer (CLCE) is a structurally coloured polymer system capable of changing its colour by mechanical deformation, due to the coupling of colour of helically aligned liquid crystal molecules and the viscoelasticity of rubber. Prof. Jan Lagerwall, Dr. Yong Geng and Rijeesh Kizhakidathazhath at the University of Luxembourg created colour-changing CLCE fibres that can be easily sewn into the fabric.
The team at the Faculty of Science, Technology and Medicine developed a simple and scalable method to pull out fibres from CLCE precursor solution by adjusting the viscoelasticity of the solution. The colour of the fibres shifts continuously and reversibly from red to blue upon stretching.
Then, the researchers demonstrate the robustness of the CLCE fibres in garments by subjecting it to repeated stretching, machine washing and abrasion. The fibres remain colourful and mechanoresponsive. Such robust and colour-changing fibres open up numerous applications in wearable technology and other areas benefiting from autonomous strain sensing or detection of critically strong deformations.
Journal
Nature Materials
Subject of Research
Not applicable
Article Title
Robust cholesteric liquid crystal elastomer fibres for mechanochromic textiles
Article Publication Date
29-Sep-2022