recent_advances_in_fluoropolymers

recent_advances_in_fluoropolymers - Recent Advances in...

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Recent Advances in Fluoropolymers: Copolymers of Tetrafluoroethylene and Related Fluorinated Molecules. Giovanni Rojas University of Florida November 25 th 2003 KEYWORDS : Tetrafluoroethylene, fluoropolymer, suspension, emulsion, Supercritical carbon dioxide. Abstract: Tetrafluoroethylene copolymers have been prepared using regular or perfluorinated solvents, aqueous medium, and surface modification by radiation and supercritical carbon dioxide. The use of perfluorinated solvents is frequently avoided because of environmental problems. Water polymerizations contemplate suspension, emulsion and Cyclodextrines processes, although the use of surfactants (usually fluorinated) is required. Surface modification of polymer films is a cleaner methodology but stereo regular polymers are not guaranteed. The most promising method is carried out under supercritical CO 2 conditions, solving the environmental problem of the use chlorofluoro compounds; furthermore the industrial use of CO 2 makes PTFE production much cheaper. Contents 1 INTRODUCTION. .............................................................................................................................. 2 2 COPOLYMERIZATION OF TETRAFLUOROETHYLENE AND MONOMERS RELATED EMPLOYING ORGANIC SOLVENTS. .................................................................................................... 3 2.1 POLYMERIZATION INVOLVING REGULAR ORGANIC SOLVENTS. ..................................................... 4 2.2 POLYMERIZATION INVOLVING FLUORINATED AND PERFLUORINATED SOLVENTS . ........................ 6 3 COPOLYMERIZATION OF TETRAFLUOROETHYLENE AND RELATED FLUOROPOLYMERS UNDER AQUEOUS MEDIUM . ......................................................................... 9 3.1 SUSPENSION PROCESS. .................................................................................................................. 9 3.2 EMULSION PROCESS . .................................................................................................................... 9 3.3 CYCLODEXTRINES IN POLYMER SYNTHESIS. ............................................................................... 11 4 SURFACE MODIFICATION OF TETRAFLUOROETHYLENE AND RELATED POLYMERS . .............................................................................................................................................. 13 4.1 INCORPORATION OF METALLIC ATOMS INTO POLYTETRAFLUOROETHYLENE SURFACES . ............ 15 4.2 DEGRADATION MECHANISM OF TETRAFLUOROETHYLENE COPOLYMERS. .................................. 16 5 POLYMERIZATION IN SUPERCRITICAL CO 2 ....................................................................... 17 6 CONCLUSION . ................................................................................................................................ 18 7 REFERENCES. ................................................................................................................................. 18
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2 1 Introduction Teflon is one of the most important and representative fluoropolymers; it was synthesized
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recent_advances_in_fluoropolymers - Recent Advances in...

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