Radical Copolymerization of α,β-Difluoroacrylic Acid with Vinylidene Fluoride

• Published in: Macromolecules Vol. 43; no. 11; pp. 4879 - 4888
• Main Authors: Boschet, Frédéric, Cracowski, Jean-Marc, Montembault, Véronique, Ameduri, Bruno
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 08.06.2010
• Subjects: Applied sciences; Chemical Sciences; Copolymerization; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Polymers; Preparation, kinetics, thermodynamics, mechanism and catalysts; Acrylic copolymer; Fluorine containing copolymer; Property composition relationship; Vinylidene fluoride copolymer; Preparation; Solution copolymerization; Alfrey Price parameter; Acid copolymer; Radical copolymerization; Experimental study; Reactivity ratio; Thermal stability; NMR; thermal stability; β-difluoroacrylic acid; vinylidene fluoride; radical copolymerization; kinetics of copolymerization
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma100506e

The synthesis of α,β-difluoroacrylic acid (FHCCF−CO2H, DiFAA) and its radical copolymerization with vinylidene fluoride (CH2CF2, VDF) are presented. First, DiFAA was synthesized in three steps from the radical addition of methanol onto 1,2-dichloro-1,2-difluoroethylene leading to HCFClCFClCH2OH in 78% yield. Then, oxidation of the hydroxymethyl end-group followed by zinc-mediated dehalogenation of 2,3-dichloro-2,3-difluoropropanoic acid led to (Z) isomer of DiFAA in 29% overall yield. The homopolymerization of DiFAA was successfully achieved by radical polymerization initiated by tert-butylperoxypivalate (TBPPi) at 74 °C in 32% yield. Its radical copolymerization with VDF was carried out for the first time and at various compositions leading to functional poly(VDF). The resulting poly(VDF-co-DiFAA) copolymers, characterized by 1H and 19F NMR spectroscopies, exhibited a statistic microstructure. The kinetics of this radical copolymerization led to the assessment of the reactivity ratios (r DiFAA = 0.86 and r VDF = 0.34 at 74 °C), and showed that DiFAA was more reactive than VDF in copolymerization. Thermal properties of these poly(DiFAA-co-VDF) copolymers were also investigated. Differential scanning calorimetry analyses showed a decrease of the glass transition temperature (T g) with increasing VDF content. Calculations using the Fox’s equation led to the determination of the T g for poly(DiFAA) homopolymer (T g = 145 °C) in good agreement with the literature. Thermogravimetric analyses displayed increased thermostability of the resulting copolymers with increasing VDF content.