Rupture of Polydomain and Monodomain Liquid Crystal Elastomer

Liquid crystal elastomer (LCE) has been recently explored extensively to make diverse active structures and devices. Depending on synthetic process, LCE can be made either polydomain or monodomain when ambient temperature is below isotropic clearing temperature. In the applications, LCE may be subjected to large mechanical stretch or force and break apart. The capability of predicting the rupture of LCE under different loading conditions is crucial for the applications. However, according to our knowledge, there is no report on fracture energy measurement of LCE. In this paper, we measured fracture energy of both monodomain and polydomain LCEs using pure shear test. We found that polydomain LCE has significantly higher fracture energy than monodomain one. We suggest that the increase of fracture energy in polydomain LCE is attributed to stretch-induced polydomain-to-monodomain transition near the crack tip of the material.