No abstract

International audienceModified fluorinated electroactive poly(VDF-co-TrFE) copolymers with improved adhesion properties,on glass or metal substrates, are presented. Vinylidene fluoride (VDF) and trifluoroethylene (TrFE) wereterpolymerized with 1 to 8 mol% of 2-(trifluoromethyl)acrylic acid (MAF) as an adhesion-promotingmonomer. Monitoring the evolution of the reactor pressure and of the 19F NMR spectra of the terpolymerover the course of solution polymerization revealed the very pronounced compositional heterogeneity ofthe resulting terpolymer. The terpolymerization was scaled-up and implemented under aqueous suspensionconditions in a 3 L-autoclave. This aqueous process, more industrially viable, was successful in spiteof the undesirable addition reaction of water onto MAF producing 3-hydroxy-2-(trifluoromethyl)propanoicacid. The structure of the resulting polymers was characterized in detail by 1H, 19F NMR and FTIRspectroscopies, and their physical properties (thermal, adhesion and electroactive) were examined. Thedecarboxylation of MAF, observed by TGA to occur at ca. 250 °C, is not a limitation for the targeted applications.A MAF content of 1 mol% was shown to be sufficient to provide very good adhesion onto glassand metal substrates, and also to decrease the water contact angle from 104° (reference poly(VDFco-TrFE) copolymer) to 86° (terpolymer containing 1 mol% of MAF). Polarization studies revealed that theterpolymers exhibited identical ferroelectric behavior as unmodified poly(VDF-co-TrFE) copolymers,characterized by a wide hysteresis (Ec = 60 MVm−1) and a high saturation polarization (Psat = 77 mC m−2).This study reports the first electroactive fluorocopolymers with improved adhesion, and paves the wayfor better incorporation of fluorinated electroactive thin films in multilayer films for flexible electronicdevices