2024-03-29T01:07:03Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/1157762023-01-26T16:37:28Zcom_10261_56com_10261_3col_10261_309
00925njm 22002777a 4500
dc
Smith, Z. P.
author
Czenkusch, K.
author
Wi, S.
author
Gleason, K. L.
author
Hernández, Guiomar
author
Doherty, C. M.
author
Konstas, K.
author
Bastow, T. J.
author
Álvarez, C.
author
Hill, A. J.
author
Lozano López, Ángel Emilio
author
Paul, D. R.
author
Freeman, Benny D.
author
2014
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.
Polymer 55: 6649-6657 (2014)
http://hdl.handle.net/10261/115776
10.1016/j.polymer.2014.10.055
Polybenzoxazoles
Gas separation membranes
TR polymers
Investigation of the chemical and morphological structure of thermally rearranged polymers