Deconvoluting the Contribution of Polymerization Temperature\nto Liquid Crystalline Elastomer Actuation

Liquid\ncrystalline elastomers (LCEs) are increasingly considered\nas advanced materials that prospectively may enable distinctive functional\nutility in medical devices, consumer goods, and aerospace. This report\ndetails the contribution of the polymerization conditions within the\nthermotropic phase behavior of material compositions and systematically\nillustrates the substantive contributions of nematic genesis to the\nresulting thermomechanical response. Compositionally identical LCEs\nwere polymerized in the monodomain orientation over a range of temperatures\nin the nematic phase of the formulations. Upon polymerization, the\nthermomechanical response of the compositionally identical LCEs prepared\nover a range of temperatures had a 15% increase in the nematic to\nisotropic transition temperature (<i>T</i><sub>NI</sub>),\n50% decrease in the magnitude of the thermomechanical response, and\n25% decrease in total actuation stroke. X-ray scattering was utilized\nto elucidate the correlation of polymerization temperature (e.g.,\nnematic genesis) to the orientational order of LCEs. These measurements\nshow, in addition to differences in mechanical properties between\nthe LCEs, the nematic genesis of the polymerization reaction affects\nthe overall degree of liquid crystallinity, the coherence length of\nthe cybotactic nematic domains, and the orientation parameter of the\nLCE.