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

trans-1,3,3,3-Tetrafluoropropene (1234ze) was copolymerized under free radical conditions with vinylidene fluoride (VDF) and trifluoroethylene (TrFE), for the first time, leading to statistical poly(VDF-ter-TrFE-ter-1234ze) electroactive terpolymers. The reactivity ratios of the three comonomer couples were determined (r VDF = 0.77; r TrFE = 0.32), (r VDF = 1.67; r 1234ze = 0.00), and (r TrFE = 7.56; r 1234ze = 0.00), at 48 °C, using the nonlinear fitting Mayo−Lewis method. 1234ze was shown to be regularly incorporated in the terpolymer chains over the entire course of the reaction providing terpolymer chains with statistical monomer distribution and almost constant composition. These new VDF/TrFE-based terpolymers were characterized by 1 H and 19 F liquid state NMR spectroscopy. The characteristic NMR signals of the VDF− 1234ze dyads were identified by comparing the NMR spectral signatures of a poly(VDF 82 -co-1234ze 18 ) copolymer and of a terpolymer. The thermal and electroactive properties of poly(VDF-ter-TrFEter-1234ze) terpolymers, with 1234ze content ranging from 0 to 6 mol % and molar masses above 55 kg/mol, were assessed. The randomly distributed 1234ze termonomer units induced the decreases of both the Curie and the melting temperatures of the terpolymer even at low termonomer content (T Curie = 70 °C and T m = 126 °C and T Curie = 72 °C and T m = 150 °C; for a poly(VDF 69 -ter-TrFE 28 -ter-1234ze 3 ) terpolymer and a poly(VDF 65 -co-TrFE 35 ) copolymer, respectively). Films of the terpolymers were cast, and their electroactive properties were examined by D−E loops measurements. They showed that the presence of 1234ze decreased the remnant polarization (P r = 45 mC/m 2 for a poly(VDF 65 -co-TrFE 35 ) copolymer to 28 mC/m 2 for a poly(VDF 69 -ter-TrFE 25 -ter-1234ze 6 ) terpolymer) probably because it also decreased the crystallinity of the terpolymer. The combination of the studies of the reactivity of the monomers, of the terpolymer microstructures, and of the assessment of their physical properties provides insights into their structure−property relationship.