Ionene segmented block copolymers containing imidazolium cations: Structure-property relationships as a function of hard segment content |
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Authors: | Sharlene R Williams Karen I Winey |
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Affiliation: | a Department of Chemistry, Macromolecules and Interfaces Institute, Virginia Tech, Blacksburg, VA 24061, USA b Chemical and Biomolecular Engineering Department, University of Pennsylvania, Philadelphia, PA 19104, USA c Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA |
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Abstract: | Imidazolium ionene segmented block copolymers were synthesized from 1,1′-(1,4-butanediyl)bis(imidazole) and 1,12-dibromododecane hard segments and 2000 g/mol PTMO dibromide soft segments. The polymeric structures were confirmed using 1H NMR spectroscopy, and resonances associated with methylene spacers from 1,12-dibromododecane became more apparent as the hard segment content increased. TGA revealed thermal stabilities ≥250 °C for all imidazolium ionene segmented block copolymers. These ionene segmented block copolymers containing imidazolium cations showed evidence of microphase separation when the hard segment was 6-38 wt%. The thermal transitions found by DSC and DMA analysis found that the Tg and Tm of the PTMO segments were comparable to PTMO polymers, namely approximately −80 °C and 22 °C, respectively. In the absence of PTMO soft segments the Tg increased to 27 °C The crystallinity of the PTMO segments was further evidence of microphase separation and was particularly evident at 6, 9 and 20 wt% hard segment, as indicated in X-ray scattering. The periodicity of the microphase separation was well-defined at 20 and 38 wt% hard segment and found to be approximately 10.5 and 13.0 nm, respectively, for these ionenes wherein the PTMO soft segment is 2000 g/mol. Finally, the 38 and 100 wt% hard segment ionenes exhibited scattering from correlations within the hard segment on a length scale of approximately 2-2.3 nm. These new materials present structure on a variety of length scales and thereby provide various routes to controlling mechanical and transport properties. |
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Keywords: | Ionenes Imidazolium X-ray scattering |
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