Polytetrafluoroethylene copolymerization

Several graft copolymerizations were described by Ballantine (17, 64), Henglein (104, 105) and coworkers. Different monomer-polymer systems were examined styrene on polymethyl methacrylate, poly-2, 5-dichlorostyrene, polytetrafluoroethylene, polyethylene, polypropylene and polyisobutylene, acrylonitrile on polyethylene, rubber, polymethyl methacrylate and dimethyl polysiloxane, vinylpyrrolidone and acroleine on polymethyl methacrylate. The results agree with the preceding ones moreover they show the influence of the swelling and diffusion of the monomer into the polymer. 

Polymeric membranes are monolithic, continuously porous materials. Membranes can be produced from numerous organic polymers including polyalkanes (polyethylene and polypropylene) and their fluorinated derivatives [polyvinylidene fluoride and polytetrafluoroethylene (PTFE)]. Once formed, a membrane can be chemically functionalized by a number of methods including direct conversion of functional groups in the bulk polymer, coating of the surface with a preformed polymer, or graft copolymerization of reactive monomers onto the membrane surface. 

Kostov, G.K. and Turmanova, S.C. 1997. Radiation-initiated graft copolymerization of 4-vinylpyridine onto polyethylene and polytetrafluoroethylene films and anion-exchange membranes therefrom. J Appl Polym Sci. 64 1469-1475. 

Polymers with a polytetrafluoroethylene (PTFE) backbone and pendant perfluorosulfonate or perfluor-ocarboxylate groups have become commercially important materials, although they are expensive. The sulfonates were introduced as Nafion by Du Pont in the early 1970s and the carboxylates as Flemion by Asahi Glass in 1978. They are made by free-radical copolymerization of tetrafluoroethylene and perfluorovinyl monomers giving precursor copolymers, (XXII) and (XXIII), which can be post-functionalized by hydrolysis to generate sulfonic and carboxylic acid groups. The perfluorovinyl... 

Our studies showed that the inner surface of the cardiovascular System was hydrophobic surface with Yc(Zis.)=29 dyne/cm. We could easily select polytetrafluoroethylene as the material with a smaller critical surface tension than 29 dyne/cm to make test materials. Figure-3 shows the surface properties of the inner surface of the cardiovascular system and polytetrafluoroethylene in relation to wetting properties viewed from Zisman s plots. How should we treat polytetrafluoroethylene to minimize the difference in wetting properties between the surface of polytetrafluoroethylene and the inner surface of the cardiovascular system. We tried to improve the surface properties of polytetrafluoroethylene by using the graft copolymerization method and expansion method. 

Copolymers of VF with vinylidene fluoride [75-38-7] and tetrafluoroethylene [116-14-3] also have been prepared with this initiation system. VF tends toward alternation with tetrafluoroethylene and incorporates preferentially in copolymerization with vinylidene fluoride [see Perfluorinated Polymers, Polytetrafluoroethylene Vinylidene Fluoride Polymers]. 

Perfluroalkoxy polymer or PFA is one of the most important meltprocessible fluoroplastics due to its relative ease of processing and high service temperature equivalent to polytetrafluoroethylene (260°C). It also has the same excellent chemical resistance and low friction properties as PTFE. Perfluroalkoxy polymers are prepared by copolymerization of a perfluoroalkylvinyl ethers (Rf—O—CF=CF2, where Rj is a perfluorinated alkyl group) with tetrafluoroethylene. Examples of commercially utilized ethers include perfluoromethyl-vinyl ether (CFg—O—CF=CF2), perfluoroethylvinyl ether (C2F5—O—CF=CF2) and perfluoropropylvinyl ether (C3F7—O—CF=CF2). Several percent of ether is incorporated in a copolymer. 

Yamaki, T., Tsukada, J., Asano, M., Katakai, R. and Yoshida, M. (2007) Preparation of highly stable ion exchange membranes by radiation-induced graft copolymerization of styrene and bis(vinyl phenyl)ethane into crossUnked polytetrafluoroethylene films. J. Fuel Cell Sci. Technol. 4, 56-64. 

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