Abstract
Liquid crystalline elastomers (LCEs) exhibit unique shape memory behavior due to the combination of liquid crystalline orientation and rubber elasticity. Multiscale structural characterization of these materials upon deformation is crucial to understanding their structure-property relationships. In this work, the structure evolution of an epoxy-based, main-chain LCE with deuterated flexible spacers upon uniaxial mechanical deformation is investigated at different length scales. Wide-angle and small-angle X-ray scattering (WAXS/SAXS) reveal the presence of smectic polymorphism and rotations of the smectic domains upon mechanical stretching, which is also confirmed by small-angle neutron scattering (SANS). Importantly, the selective deuteration enables an improved neutron scattering contrast between the smectic and amorphous domains. SANS patterns of the deformed, deuterated LCE exhibit strong scattering streaks that are not observed in SAXS or SANS of hydrogenated LCE, indicating the presence of highly aligned amorphous domains. The macroscopic orientation also results in the formation of structures in the micrometer scale revealed by the ultrasmall-angle neutron scattering (USANS) experiment.
| Original language | English |
|---|---|
| Pages (from-to) | 10574-10582 |
| Number of pages | 9 |
| Journal | Macromolecules |
| Volume | 54 |
| Issue number | 22 |
| DOIs | |
| State | Published - Nov 23 2021 |
Funding
This work was supported by the Air Force Office of Scientific Research (FA-9550-12-1-0108). SAXS/WAXS data were measured on the Xeuss 3 SAXS/WAXS instrument via the ORNL instrumentation pool, and the data were analyzed at the Center for Nanophase Materials Sciences (CNMS), which is a U.S. Department of Energy, Office of Science User Facility. The authors thank Ken Littrell at ORNL for assistance in neutron scattering experiments.