Production of Fluoroelastomers

Moore, Albert L.

doi:10.1016/b978-081551517-3.50007-1

Cited by 15 publications

(45 citation statements)

References 13 publications

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“…The strength of C–F bonds in fluorinated compounds conveys properties such as exceptional thermal and chemical stability, inertness to acids and common solvents, low inflammability, and low dielectric constant. Consequently, fluorinated compounds, including fluoropolymers, play an important role in the development of new materials for advanced applications (coatings, transmission fluids, soft lithography, high-performance lubricants, and membranes). − …”

Section: Introductionmentioning

confidence: 99%

Atom Transfer Radical Polymerization with Different Halides (F, Cl, Br, and I): Is the Process “Living” in the Presence of Fluorinated Initiators?

et al. 2016

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Atom transfer radical polymerization (ATRP) is often used for grafting from fluorinated polymers. Nevertheless, the possibility to initiate an ATRP from a C–F functionality and the activity of the catalysts in the presence of fluoride anions are essentially unexplored. Therefore, we investigated the thermodynamics and kinetics of C–F bond activation by ATRP catalysts and compared it with other halide systems. The ATRP equilibrium constant was estimated to be small for the reaction between [CuITPMA]+ and benzyl fluoride (TPMA = tris(2-pyridylmethyl)amine). However, [CuITPMA]+ could react with the more active initiator diethyl fluoromalonate (DEFM). With DEFM as initiator and CuIBr/TPMA as catalyst, ATRP of methyl acrylate and styrene displayed initiation efficiencies of 73% and 95%, respectively. ATRP deactivation by [F–CuIITPMA]+ was slow and followed by even slower activation of newly formed C–F bonds, leading to limited conversion. Comparison with other halides indicates that Br- and Cl-based ATRP systems are more efficient that I- and F-based systems.

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Section: Introductionmentioning

confidence: 99%

Atom Transfer Radical Polymerization with Different Halides (F, Cl, Br, and I): Is the Process “Living” in the Presence of Fluorinated Initiators?

et al. 2016

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“…20 In the present work, we demonstrate that a simple semibatch emulsion polymerization of methoxy-PEG2000 acrylate macromonomer and heptafluorobutyl methacrylate results in highly monodisperse PEGylated spheres. Semibatch emulsion polymerization is widely used in industry because of its operational flexibility, 21 but it has seen comparatively little use in academia. When applied, it has been the monomer that has been fed to the reaction mixture.…”

Section: Introductionmentioning

confidence: 99%

Monodisperse PEGylated Spheres: An Aqueous Colloidal Model System

2014

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Fluorinated core–shell spheres have been synthesized using a novel semibatch emulsion polymerization protocol employing slow feeding of the initiator. The synthesis results in aqueous dispersions of highly monodisperse spheres bearing a well-defined poly(ethylene glycol) graft (PEGylation). Measurements are consistent with the synthesis achieving a high grafting density that moreover consists of a single PEG layer with the polymer significantly elongated beyond its radius of gyration in bulk. The fluorination of the core of the particles confers a low index of refraction such that the particles can be refractive index matched in water through addition of relatively small amounts of a cosolvent, which enables the use of optical and laser-based methods for studies of concentrated systems. The systems exhibit an extreme stability in NaCl solutions, but attractions among particles can be introduced by addition of other salts, in which case aggregation is shown to be reversible. The PEGylated sphere dispersions are expected to be ideally suited as model systems for studies of the effect of PEG-mediated interactions on, for instance, structure, dynamics, phase behavior, and rheology.

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“…Its estimated molar mass was 39,000 g/mol by 19 F NMR. However, in contrast with the CF 3 -terminated PVDF, which was a powder, the co- and terpolymers were obtained as white gums due to the high contents of HFP and PMVE. , …”

Section: Resultsmentioning

confidence: 94%

Chain-End Functionality: The Key Factor toward Fluoropolymer Thermal Stability

et al. 2021

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The aqueous radical homopolymerization of vinylidene fluoride (VDF), as well as its copolymerizations with hexafluoropropylene (HFP) or perfluoromethyl vinyl ether (PMVE), and its terpolymerization with HFP and PMVE, initiated by trifluoromethyl radicals ( • CF 3 ), generated from the ammonium persulfate (APS) and potassium trifluoromethyl sulfinate (CF 3 SO 2 K) redox system are presented. The optimization of the experimental conditions in terms of initial reactant molar ratios, temperature, and reaction time was achieved. The best results were obtained at 60 °C, in water, without any surfactant, using 0.9 equiv of APS as the oxidant with respect to CF 3 SO 2 K. PVDF, poly(VDF-co-HFP), poly(VDF-co-PMVE), or poly(VDF-ter-PMVE-ter-HFP) copolymers were obtained in high yields (varying between 89 and 100%) and with molar masses up to 113,000 g/mol.The 1 H and 19 F NMR spectroscopies revealed that, under optimized conditions, the formed chain ends were exclusively CF 3 or CF 2 H. The influence of the nature of the chain end on the thermal stability showed that PVDFs terminated by CF 3 were more stable than their analogues bearing sulfate end groups by 120 °C. In addition, the prepared CF 3 -PVDFs had 53% of crystallinity (compared to 47% for PVDF initiated from APS alone), which offers excellent resistance to conventional organic solvents including dimethyl sulfoxide, acetone, and dimethyl formamide.

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Production of Fluoroelastomers

Cited by 15 publications

References 13 publications

Atom Transfer Radical Polymerization with Different Halides (F, Cl, Br, and I): Is the Process “Living” in the Presence of Fluorinated Initiators?

Atom Transfer Radical Polymerization with Different Halides (F, Cl, Br, and I): Is the Process “Living” in the Presence of Fluorinated Initiators?

Monodisperse PEGylated Spheres: An Aqueous Colloidal Model System

Chain-End Functionality: The Key Factor toward Fluoropolymer Thermal Stability

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