@article{51ad1471bc5d45948da3d6b90d5085d9,
title = "Investigation of the chemical and morphological structure of thermally rearranged polymers",
abstract = "Reacting ortho-functional poly(hydroxyimide)s via a high-temperature (i.e., 350 °C-450°C) solid-state reaction produces polymers with exceptional gas separation properties for separations such as CO2/CH4, CO2/N2, and H2/CH4. However, these reactions render these so-called thermally rearranged (TR) polymers insoluble in common solvents, which prevent the use of certain experimental characterization techniques such as solution-state nuclear magnetic resonance (NMR) from identifying their chemical structure. In this work, we seek to identify the chemical structure of TR polymers by synthesizing a partially soluble TR polymer from an ortho-functional poly(hydroxyamide). The chemical structure of this TR polymer was characterized using 1-D and 2-D NMR. By use of cross-polarization magic-angle spinning 13C NMR, the structure of the polyamide-based TR polymer was compared to that of a polyimide-based TR polymer with a nearly identical proposed structure. The NMR spectra suggest that oxazole functionality is formed for both of these TR polymers. Furthermore, gas permeation results are provided for the precursor polymers and their corresponding TR polymer. The differences in transport properties for these polymers result from differences in the isomeric nature of oxazole-aromatic linkages and morphological differences related to free volume and free volume distribution.",
keywords = "Gas separation membranes, Polybenzoxazoles, TR polymers",
author = "Smith, {Zachary P.} and Katrina Czenkusch and Sungsool Wi and Gleason, {Kristofer L.} and Guiomar Hern{\'a}ndez and Doherty, {Cara M.} and Kristina Konstas and Bastow, {Timothy J.} and Cristina {\'A}lvarez and Hill, {Anita J.} and Lozano, {Angel E.} and Paul, {Donald R.} and Freeman, {Benny D.}",
note = "Funding Information: Department of Energy Office of Science Graduate Fellowship Program (Grant # DE-AC05-06OR23100 ), Department of Energy Office of Science Division of Chemical Sciences, Geosciences, and Biosciences (Grant # DE-FG02-02ER15362 ), National Science Foundation Cooperative Agreement (Grant # DMR-0084173 ). Funding Information: The authors gratefully acknowledge support from the Department of Energy Office of Science Graduate Fellowship Program (Grant # DE-AC05-06OR23100), which provided funding for conducting research at the Commonwealth Scientific and Industrial Research Organization (CSIRO) and The Instituto de Ciencia y Tecnolog{\'i}a de Pol{\'i}meros . Additional funding for polymer synthesis, casting, and permeability measurements was provided by Department of Energy Office of Science, Division of Chemical Sciences, Geosciences, and Biosciences (Grant # DE-FG02-02ER15362). Solid-state NMR work was supported by the National High Magnetic Field Laboratory through National Science Foundation Cooperative Agreement (DMR-0084173) and by the State of Florida . Publisher Copyright: {\textcopyright} 2014 Elsevier Ltd. All rights reserved. Copyright: Copyright 2018 Elsevier B.V., All rights reserved.",
year = "2014",
month = dec,
day = "15",
doi = "10.1016/j.polymer.2014.10.055",
language = "English",
volume = "55",
pages = "6649--6657",
journal = "Polymer",
issn = "0032-3861",
publisher = "Elsevier",
number = "26",
}