Tetrafluoroethylene copolymers with sulfonyl fluoride pendants: Syntheses in supercritical carbon dioxide, polymerization behaviors, and properties

Abstract

Copolymerizations of tetrafluoroethylene (TFE) and perfluoro(3,6-dioxa-4- methyl-7-octen)sulfonyl fluoride (PSVE) initiated by bis(perfluoro-2-n- propoxypropionyl) peroxide in supercritical carbon dioxide are investigated. The reactivity ratios for TFE (rTFE) and PSVE (rPSVE) are calculated to be 7.85, 0.079 and 7.92, 0.087 according to Fineman-Ross and Kelen-Tudos methods, respectively. The glass transition temperatures of the copolymers increase with increasing in PSVE content. Comparison studies on above copolymers and another fluorinated sample prepared in emulsion show that the copolymers have comparable properties to the fluorinated one, thus offering an economic way to improve the properties of TFE-PSVE copolymers for their applications in diverse fields. A series of TFE-PSVE copolymers are synthesized in supercritical carbon dioxide (sc-CO2) using bis(perfluoro-2-n- propoxypropionyl) peroxide (BPPP) as the initiator. Copolymers with PSVE fractions varying from 5.6 to 18.6 mol-% are obtained in 12.6-66.3 mol-% yield. The copolymers have comparable properties to those of the fluorinated polymer prepared in emulsion, thus saving an expensive fluorination step. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.