Liquid-Crystal Order during Synthesis Affects Main-Chain Liquid-Crystal Elastomer Behavior
dc.contributor.ORCID | 0000-0001-5154-6378 (Saed, MO) | en_US |
dc.contributor.author | Traugutt, N. A. | en_US |
dc.contributor.author | Volpe, R. H. | en_US |
dc.contributor.author | Bollinger, M. S. | en_US |
dc.contributor.author | Saed, Mohand O. | en_US |
dc.contributor.author | Torbati, A. H. | en_US |
dc.contributor.author | Yu, K. | en_US |
dc.contributor.author | Dadivanyan, Natalia | en_US |
dc.contributor.author | Yakacki, C. M. | en_US |
dc.contributor.utdAuthor | Saed, Mohand O. | en_US |
dc.date.accessioned | 2018-09-14T19:17:37Z | |
dc.date.available | 2018-09-14T19:17:37Z | |
dc.date.created | 2017-09-20 | |
dc.date.issued | 2017-09-20 | en_US |
dc.description | Full text access for Treasures at UT Dallas is restricted to current UTD affiliates. | en_US |
dc.description.abstract | This study presents the first direct comparison of the influence of liquid-crystal order during synthesis on the thermo-mechanical behaviors of main-chain liquid-crystal elastomers (LCEs) in thiol-acrylate networks. Six polydomain nematic elastomer (PNE) chemistries were compared directly by synthesizing with the mesogens in either an isotropic state (i-PNE) or a nematic state (n-PNE). The i-PNE networks were created in the presence of solvent, which disrupted any liquid-crystal order during network formation. Conversely, the n-PNE networks were created without the presence of solvent below the isotropic transition (T_{NI}). Differential scanning calorimetry (DSC) was first performed, and it showed that i-PNE networks experienced a clearly defined nematic-to-isotropic transition upon heating, whereas the transition in n-PNE networks was unable to be identified, which may be the result of a nematic-to-paranematic phase transition. Dynamic mechanical analysis (DMA) tests revealed that while both networks maintained elevated loss tangent in the nematic region, only i-PNE networks prominently displayed dynamic soft elasticity behavior. The two-way shape switching behaviors of LCE networks were examined using actuation tests under a 100 kPa bias stress. It showed that the strain amplitude strongly depends on synthesis history; it ranges from 66% to 126% in i-PNE samples and 3% to 61% in n-PNE samples. To help interpret the different actuation strain behaviors between i-PNEs and n-PNEs, wide-angle X-ray scattering (WAXS) was then performed where the LCE samples were strained to 40%. The results showed that order parameter (S) in n-PNE samples (ranging from 0.37 to 0.50) is lower than that in i-PNE samples (0.54 for all cases), and the parameter decreased as the cross-linking density increased. The stress-strain behaviors of the LCE networks measured from uniaxial tension tests revealed that all i-PNE samples had a lower soft-elasticity plateau during loading compared to the n-PNE samples. Finally, free-standing strain recovery of LCE samples after being strained to 100% was investigated. Immediately after removing stress on the samples, i-PNE and n-PNE samples recovered 14% to 38% and 27% to 73% of strain, respectively. We discuss the advantages and disadvantages of the different synthetic histories on LCE design. | en_US |
dc.description.department | Erik Jonsson School of Engineering and Computer Science | en_US |
dc.description.sponsorship | NSF CAREER Award CMMI-1350436 | en_US |
dc.identifier.bibliographicCitation | Traugutt, N. A., R. H. Volpe, M. S. Bollinger, M. O. Saed, et al. 2017. "Liquid-crystal order during synthesis affects main-chain liquid-crystal elastomer behavior." Soft Matter 13(39): 7013-7025. | en_US |
dc.identifier.issn | 1744-683X | en_US |
dc.identifier.issue | 39 | en_US |
dc.identifier.uri | http://hdl.handle.net/10735.1/6078 | |
dc.identifier.volume | 13 | en_US |
dc.language.iso | en | en_US |
dc.publisher | Royal Soc Chemistry | en_US |
dc.relation.uri | http://dx.doi.org/10.1039/c7sm01405h | |
dc.rights | ©2017 The Royal Society of Chemistry | en_US |
dc.source.journal | Soft Matter | en_US |
dc.subject | Nematic liquid crystals | en_US |
dc.subject | Elastomers | en_US |
dc.subject | Materials—Mechanical properties | en_US |
dc.subject | Actuators | en_US |
dc.subject | Elasticity | en_US |
dc.subject | Polymers | en_US |
dc.subject | Muscles | en_US |
dc.title | Liquid-Crystal Order during Synthesis Affects Main-Chain Liquid-Crystal Elastomer Behavior | en_US |
dc.type.genre | article | en_US |
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