title: Claisen thermally rearranged (CTR) polymers.
abstract: Thermally rearranged (TR) polymers, which are considered the next-generation of membrane materials because of their excellent transport properties and high thermal and chemical stability, are proven to have significant drawbacks because of the high temperature required for the rearrangement and low degree of conversion during this process. We demonstrate that using a [3,3]-sigmatropic rearrangement, the temperature required for the rearrangement of a solid glassy polymer was reduced by 200°C. Conversions of functionalized polyimide to polybenzoxazole of more than 97% were achieved. These highly mechanically stable polymers were almost five times more permeable and had more than two times higher degrees of conversion than the reference polymer treated under the same conditions. Properties of these second-generation TR polymers provide the possibility of preparing efficient polymer membranes in a form of, for example, thin-film composite membranes for various gas and liquid membrane separation applications.
authors.affiliation: Institute of Polymer Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Str.1, 21502 Geesthacht, Germany.
authors.forename: Alberto
authors.initials: A
authors.lastname: Tena
authors.affiliation: Institute of Polymer Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Str.1, 21502 Geesthacht, Germany.
authors.forename: Sofia
authors.identifier: 0000-0003-3839-0588
authors.initials: S
authors.lastname: Rangou
authors.affiliation: Institute of Polymer Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Str.1, 21502 Geesthacht, Germany.
authors.forename: Sergey
authors.identifier: 0000-0001-8757-600X
authors.initials: S
authors.lastname: Shishatskiy
authors.affiliation: Institute of Polymer Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Str.1, 21502 Geesthacht, Germany.
authors.forename: Volkan
authors.initials: V
authors.lastname: Filiz
authors.affiliation: Institute of Polymer Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Str.1, 21502 Geesthacht, Germany.; Institute of Physical Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Abetz
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry; D055595:Mechanical Phenomena; D010539:Permeability; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*; D012117:Resins, Synthetic / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D013818:Thermogravimetry
chemical_list: D011108:Polymers; D012117:Resins, Synthetic; D002245:Carbon Dioxide; C029945:polyimide resin
keywords: Claisen rearrangement; Low-temperature thermally rearranged polymer; gas separation; membrane; natural gas purification; polybenzoxazole (PBO); polymer modification