Fluorinated polymer network

Abstract This article summarizes a large amount of work carried out in our laboratory on polysiloxane based Interpenetrating Polymer Networks (IPNs). First, a polydimethylsiloxane (PDMS) network has been combined with a cellulose acetate butyrate (CAB) network in order to improve its mechanical properties. Second, a PDMS network was combined with a fluorinated polymer network. Thanks to a perfect control of the respective rates of formation of each network it has been possible to avoid polymer phase separation during the IPN synthesis. Physicochemical analyses of these materials led to classify them as true IPNs according to Sperling s definition. In addition, synergy of the mechanical properties, on the one hand, and of the surface properties, on the other hand, was displayed. 

In 1988 Heinze and Burton reported a facile synthesis of various a,p,P-trifluorostyrenes. These trifluorostyrene compounds were reported to be imstable to cyclodimerization at room temperature when stored neat, especially the compounds that were iara-substituted with electron-donating substituents. They described the preparation of one compound, l,4-bis(trifiuorovinyl)benzene with the observation that the material gelled when allowed to stand neat overnight. They offered the explanation that the gel was a polymer network connected with fluorinated cyclobutanes. Burton later went on to utilize this dimerization reaction for the cross-linking of polyimide thermoplastics. ... 

Post-polymerization functionalization has also been applied to the synthesis of terpyridine-modified polymers [ 126]. In a recent approach, Schubert and colleagues employed this method to prepare poly(pentafluorostyrene) with terpyridines in the side chains [127]. First, poly(pentafluorostyrene) with a narrow polydispersity index of just 1.08 was synthesized by nitroxide-mediated polymerization. In a second step, this polymer was converted with amine-functionalized terpyridine under microwave heating, selectively substituting the para-fluorines. Addition of iron(II) sulfate to a solution of the terpyridine-functionalized polymer in a mixture of chloroform and methanol leads to gelation at a polymer concentration of 33 g In another work, Schubert and coworkers prepared metal-cross-Iinked polymer networks from linear and tri-arm PEG precursors, both functionalized with terpyridine at their OH-termini [128]. Quantitative functionalization of these precursors was achieved by conversion of the hydroxy-functionalized PEG derivatives with 4-chloro-2,2 6, 2"-terpyridine under basic conditions. However, quantitative cross-linking with iron(II) chloride was not observed in methanol solutions, neither at room temperature nor at elevated temperature, but only a small quantity of cross-linked material precipitated from the solution. This observation was attributed to a strong tendency of the tri-arm PEG to form intramolecular complexes, acting as a chain stopper rather than as a cross-linker. 

Chlorination ofpoly(vinyl fluoride) yields a product with 40-50% chlorine content. ination of poly(vinylidene fluoride) was reported. When mixtures of fluorine and nitrogen gases are used, the reactions are limited by the amount of diffusion of fluorine into the polymer network. X-ray photoelectron spectroscopy shows the presence of -CF2-, -CHF-, and -CH2- groups in the product. 

Darras, V. Fichet, O. Perrot, F. Boileau, S. Teyssie, D., Polysiloxane-Poly(fluorinated acrylate) Interpenetrating Polymer Networks Synthesis and Characterization. Polymer 2007,48, 687-695. 

To synthesize a non-soluble polymer network, the average functionality of the monomer combination must be greater than two. Each pair of adjacent hydroxyl or fluorine substituents may be counted as a single... 

D is the collective diffusion coefficient of the fluorinated ion exchange polymer, which is given by the effective solvent permeability coefficient and the meehanieal constant of the polymer network. The effective solvent permeability coefficient depends on the ratio of the... 

Solid-state NMR measurements of F fluorinated side-chain Azobenzene liquid crystal polymer networks (azo-LCNs) using an in situ visible light... 

Pan, H.Y., Pu, H.T., Wan, D.C., Jin, M., Chang, Z.H. (2010) Proton exchange membranes based on semi-interpenetrating polymer networks of fluorine-containing polyimide and Nafion . Journal of Power Sources, 195, 3077—3083. 

Fluorosilicones consist of PDMS backbones with some degree of fluoro-aliphatic side chains. The fluorinated group can be trifluoropropyl, nonafluorohexylmethyl, or fluorinated ether side group [78,28,79]. These polymers differ not only in substituent group, but also in the amount of fluoro-substitution relative to PDMS, the overall molecular weight and crosslink density, and the amount of branching. In most commercially available cases, these polymers are addition cure systems and the reactions are those discussed previously for silicone networks. 

These moment studies have been performed on polymer systems such as polyethylene (or on penetrants in polymer systems) in which the interacting spins (protons or fluorines) reside on the same or on adjacent atoms. This allows essentially no freedom of variation in the internuclear vectors upon deformation of the network. The primary informational content therefore relates to independent segmental orientation distributions. By placing single spins on alternate segments, there should be much greater sensitivity to changes in the chain extension upon bulk deformation. 

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