Issue 37, 2016

Microfluidic synthesis of micrometer-sized photoresponsive actuators based on liquid crystalline elastomers

Abstract

The fabrication of photoresponsive micrometer-sized liquid crystalline elastomer (LCE) particles has been described in this article for the first time. The preparation of the LCE particles using a microfluidic device by a continuous “on the fly” technique allows their fast processing with an irradiation time of less than 2 seconds. In order to accelerate the polymerization and to make the preparation of samples with thicknesses of several hundred microns possible, we modified a NIR-photoinitiation system by adding a bleaching agent. In addition to the photoinitiator, a side-chain liquid crystalline monomer containing an azo-group and a LC-crosslinker were used in the polymerization mixture. For the optimization of the polymerization parameters, LCE films were produced first. These films showed a strong thermoresponsive actuation of more than 40% upon the nematic–isotropic phase transition and changed their length by up to 34% during irradiation with light for just 8 seconds, due to the transcis isomerization of the azo-group. Fabricated particles were investigated with respect to their response to heating, irradiation with light and swelling in a good solvent. A strong photoresponsive actuation of about 24% was found for these particles, which was reversible either by irradiation with red light (8 minutes) or by an isothermal back-isomerization of the azo-group in the dark (17 minutes). The reversibility of the light induced actuation of our particles makes them promising candidates for application as artificial muscles in microrobotics.

Graphical abstract: Microfluidic synthesis of micrometer-sized photoresponsive actuators based on liquid crystalline elastomers

Supplementary files

Article information

Article type
Paper
Submitted
22 Jun 2016
Accepted
16 Aug 2016
First published
01 Sep 2016
This article is Open Access
Creative Commons BY-NC license

J. Mater. Chem. C, 2016,4, 8670-8678

Microfluidic synthesis of micrometer-sized photoresponsive actuators based on liquid crystalline elastomers

L. B. Braun, T. Hessberger and R. Zentel, J. Mater. Chem. C, 2016, 4, 8670 DOI: 10.1039/C6TC02587K

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