1. ABOUT THE DATASET -------------------- Title: Dataset for 'Frustrated Smectic Liquid Crystal Elastomers as Multifunctional Mechanical Metamaterials' Creator(s): A. Street, S.R. Berrow, Z. Wang, E. Cooper, J. Mattsson, H.F. Gleeson Organisation(s): University of Leeds Rights-holder(s):Copyright 2026 University of Leeds Publication Year: 2026 Description: Auxetics are materials that show a negative Poisson’s ratio, i.e. thickening when under strain. The discovery of nematic liquid crystal elastomers (LCEs) as molecular auxetic materials was a paradigm-shift in the design of mechanical metamaterials as they are tuneable, transparent, scalable, non-porous and facile to fabricate. Here, we report that smectic LCEs extend known synthetic molecular auxetics to a second family. The LCEs are acrylate-based, lightly crosslinked (~8 mol%) and polymerised in the nematic phase of a precursor mixture. The resulting smectic-A LCEs exhibit correlation lengths of a few molecular lengths, suggesting layer frustration, which we confirm occurs via the mechanism predicted by de Gennes in 1979. Three of the LCEs described exhibit negative Poisson’s ratios at strains above ~0.4, thereby marking the first observation of auxetic behaviour in smectic LCEs. Shear oscillatory measurements on the LCEs demonstrate highly anisotropic moduli, which in turn enables elucidation of highly anisotropic adhesive properties, with differences as large as 20x between geometries. Furthermore, we discern that in the homeotropic case, shear moduli are comparable in both nematic and smectic A LCEs, validating theoretical expectations for such systems. Cite as: A. Street, S.R. Berrow, J. Mattsson, H.F. Gleeson, 2025, Dataset for 'Frustrated Smectic Liquid Crystal Elastomers as Multifunctional Mechanical Metamaterials'. University of Leeds. https://doi.org/10.5518/1851. Related publication: A. Street, S.R. Berrow, J. Mattsson, H.F. Gleeson 'Frustrated Smectic Liquid Crystal Elastomers as Multifunctional Mechanical Metamaterials', 2026, Nature Communications, https://doi.org/10.1038/s41467-026-76776-x Contact: A. Street: phyastr@leeds.ac.uk 2. TERMS OF USE --------------- Copyright 2026 University of Leeds. This dataset is licensed under a Creative Commons Attribution 4.0 International Licence: https://creativecommons.org/licenses/by/4.0/ 3. PROJECT AND FUNDING INFORMATION ---------------------------------- Title: Mechanical Properties of Auxetic Liquid Crystal Elastomers Dates: 2022-2026 Funding organisation: University of Leeds, Pilkington Technology Limited 4. CONTENTS ----------- File listing Readme.txt Data.zip Adhesion_Data - Probe tack (LCE1, LCE3, and NLCE) and 90 degree peel test (LCE3) Auxetic_Smectic_Dat- Strain data in three dimensions as a tensile strain is applied to LCE1, LCE2, LCE3, LCE4, as well as rate dependent data for LCE2 Dynamic_Mechanical_Analysis_Data - Shear oscillatory data Polarised_Raman_Spectroscopy_Data - Raw and fitted polarised Raman spectroscopy data (LCE1, LCE2, LCE4) Washout_X-Ray_Data - X-Ray data for LCE1 before polymerisation, after polymerisation but before washing, and after washing Code.zip - Nelder-Mead minimisation of smectic-A free energy Where possible, files are presented as .csv or .txt to improve functionality on a wide array of machines A8OCB denotes the main mesogenic unit of the LCE in question Contained within the DMA files: Angular frequency (2pi*oscillation frequency) Step Time, Oscillation %, Oscillation Stress, Complex Viscosity (Not shown directly in the figures) Temperature, Storage Modulus, Loss Modulus, Tan(delta) (All used heavily throughout the results) 5. METHODS ---------- DMA data were taken using Texas Instruments DMA 850 Dynamic Mechanical Analysis equipment