Macroscopic sheets of negative order parameter Liquid Crystal Elastomer with high dissipation and auxetic properties*

Negative Order Parameter (NOP) Liquid Crystal Elastomers (LCEs) offer a route to new LCE actuation modes and the study of previously impossible LC systems.[1-3]

Mistry et. al. reported an acrylate LCE with a strain-induced NOP, coinciding with a negative Poisson’s ratio (auxeticity).[1,2] Jampani et. al. reported microfluidic thiol-acrylate NOP LCE shells.[3] Due to the microfluidic synthetic process, there are 2 mechanisms for the development of the NOP state in the LCE shells – the shell wall either anisotropically deswelling or being biaxial strained through osmotic pressure. [4] Results Urayama et. al. suggest the latter method does not lead to NOP states.[5]

However, here we create NOP LCEs via the biaxial straining of polydomain LCEs. Using 2 methods we prepare >2x2 cm sheets of NOP LCEs – large enough for the first characterisation of a NOP LC system. Our NOP LCEs have higher levels of energy dissipation and display auxeticity at significantly lower threshold strain compared to LCEs of conventional ordering.[2]

1. Mistry et. al. Soft Matter 14, 1301 (2018)
2. Mistry et. al. Nat. Comm. 9, 5095 (2018)
3. Jampani et. al. Sci. Adv. 5, eaaw2476 (2019)
4. J. Lagerwall ILCEC Presentation, Einhoven (2019)
5. K. Urayama ILCEC Presentation, Einhoven (2019)