FTIR spectroscopy of smectic elastomer films under lateral strain

Abstract

Abstract Polarized Fourier transform infrared (FTIR) spectroscopy is used to study the strain‐induced compression of molecular layers in oriented smectic liquid crystal elastomer films. A reversible change of the smectic layer thickness in SmA and SmC* films in response to external strain was revealed earlier by optical reflectometry and X‐ray measurements. However, these methods cannot probe the mechanism of layer compression on a molecular level. Polarized FTIR spectra show that the induced mesogenic tilt, one of the possible mechanisms, is too small to provide the dominating contribution to the layer shrinkage. The FTIR absorbance spectra of stretched samples are also evidence that there are no significant changes of the order parameter. Apparently, layer compression is achieved by a certain interpenetration of neighbouring layers, and/or compression of the interstitial backbone and spacer layers. Acknowledgements This study was supported by the Deutsche Forschungsgemeinschaft within project STA 425/14 and by the European Regional Development Fund (ERDF).