BARGAIN, François

DOMINGUES-DOS SANTOS, Fabrice

HADZIIOANNOU, Georges

PANINE, Pierre

TENCÉ-GIRAULT, Sylvie

THUAU, Damien

Bargain, François

Thuau, Damien

Panine, Pierre

Hadziioannou, Georges

Domingues-dos Santos, Fabrice

Tencé-Girault, Sylvie

Hal-Diderot

Crystal-Crystal transitions in poly(VDF-ter-TrFE-ter-CTFE): Influence of CTFE termonomers

Oskar Bordeaux

HAL Descartes

The increasing industrial interest for printed organic electronics these last years has led to the development of VDF-based electroactive polymers for numerous energy-related applications (sensors, actuators, capacitors) [1]. Depending on their CTFE content (from 0 to 10 mol %), poly (VDF-ter-TrFE-ter-CTFE), poly(vinylidene fluoride-ter-trifluoroethylene-ter-chlorotrifluoroethylene) copolymers exhibit ferroelectric (FE) or relaxor ferroelectric (RFE) properties at low temperature whereas they all present paraelectric (PE) behavior at high temperature. This thermal evolution of their electro-active properties is related to reversible crystal-crystal transitions.
Using simultaneous SAXS-WAXS experiments along thermal cycles, we studied these structural transitions for three different copolymers with various amount of CTFE (0,  5 and  10 mol %). 
We identified two types of crystalline phase at low temperature with their proper crystal-crystal transition: the first one containing all-trans conformations (orthorhombic FE phase) presents a discontinuous transition towards the hexagonal PE phase, the second one which incorporates gauche disordered conformations (orthorhombic DFE (Defective Ferroelectric) or RFE) transits continuously towards the same hexagonal PE phase. The discontinuous FE to PE transition is the predominant transition observed in the copolymer without CTFE, it is the well-known Curie transition. The unique transition observed in the terpolymer with 10 mol % of CTFE is the continuous RFE to PE transition. For the intermediate composition, we observe the coexistence of these two simultaneous phase transitions, FE to PE and RFE to PE. 
These observations are well correlated with the ferroelectric and relaxor-ferroelectric behaviors of each terpolymer. All the conclusions and discussion of this study were recently published in Polymer [2]. At the epf2019 congress, we will focus on the SAXS-WAXS structural study

DOMINGUES DOS SANTOS, Fabrice

SAM : Science Arts et Métiers

Science Arts & Métiers (SAM)is an open access repository that collects the work of Arts et Métiers Institute ofTechnology researchers and makes it freely available over the web where possible.This is an author-deposited version published in: https://sam.ensam.euHandle ID: .http://hdl.handle.net/10985/23401To cite this version :François BARGAIN, Damien THUAU, Pierre PANINE, Georges HADZIIOANNOU, FabriceDOMINGUES DOS SANTOS, Sylvie TENCÉ-GIRAULT - Crystal-Crystal transitions in poly(VDF-ter-TrFE-ter-CTFE): Influence of CTFE termonomers - 2019Any correspondence concerning this service should be sent to the repositoryAdministrator : scienceouverte@ensam.euCrystal-Crystal transitions in poly(VDF-ter-TrFE-ter-CTFE): Influence of CTFE termonomers François Bargain,1,2 Damien Thuau,3 Pierre Panine,4 Georges Hadziioannou,3 Fabrice Domingues Dos Santos,5 Sylvie Tencé-Girault1,2,6,* 1MMC, CNRS UMR-7167 ESPCI Paris, PSL Research University, 10 rue Vauquelin, 75005 Paris, France 2Arkema, CERDATO, Route du Rilsan, 27470 Serquigny, France 3LCPO, ENSCPB, Université de Bordeaux, 16 Avenue Pey-Berland, F-33607 Cedex Pessac, France 4Xenocs SA, 19, rue François Blumet, 38360 Sassenage, France 5Piezotech S.A.S.,  Arkema - CRRA, rue Henri Moissan, 69493 Pierre-Bénite Cedex, France 6PIMM, Arts et Metiers ParisTech, CNRS, Cnam, HESAM Université, 151 Bd de l’Hôpital, 75013 Paris, France * E-mail: sylvie.girault@ensam.euThe increasing industrial interest for printed organic electronics these last years has led to the development of VDF-based electroactive polymers for numerous energy-related applications (sensors, actuators, capacitors) [1]. Depending on their CTFE content (from 0 to 10 mol %), poly (VDF-ter-TrFE-ter-CTFE), poly(vinylidene fluoride-ter-trifluoroethylene-ter-chlorotrifluoroethylene) copolymers exhibit ferroelectric (FE) or relaxor ferroelectric (RFE) properties at low temperature whereas they all present paraelectric (PE) behavior at high temperature. This thermal evolution of their electro-active properties is related to reversible crystal-crystal transitions. Using simultaneous SAXS-WAXS experiments along thermal cycles, we studied these structural transitions for three different copolymers with various amount of CTFE (0,  5 and  10 mol %).  Fig. 1: Results of simultaneous SAXS-WAXS experiments during cooling and heating for poly(VDF-ter-TrFE-ter-CTFE) with various amount of CTFE. The ordinate axis is the temperature and the abscissa axis is q (SAXS) or 2θ (WAXS).  Each line represents the scattering intensity coded with color from black to red for lowest to highest intensity.  We identified two types of crystalline phase at low temperature with their proper crystal-crystal transition: the first one containing all-trans conformations (orthorhombic FE phase) presents a discontinuous transition towards the hexagonal PE phase, the second one which incorporates gauche disordered conformations (orthorhombic DFE (Defective Ferroelectric) or RFE) transits continuously towards the same hexagonal PE phase. The discontinuous FE to PE transition is the predominant transition observed in the copolymer without CTFE, it is the well-known Curie transition. The unique transition observed in the terpolymer with 10 mol % of CTFE is the continuous RFE to PE transition. For the intermediate composition, we observe the coexistence of these two simultaneous phase transitions, FE to PE and RFE to PE.  These observations are well correlated with the ferroelectric and relaxor-ferroelectric behaviors of each terpolymer. All the conclusions and discussion of this study were recently published in Polymer [2]. At the epf2019 congress, we will focus on the SAXS-WAXS structural study.   ACKNOWLEDGEMENTS: The authors are grateful to French National Agency of Research and Technology (ANRT) and Arkema for supporting this work at the MMC laboratory (CIFRE convention no. 2014/0573). We are also thankful to ELORPrintTec ANR-10-EQPX-28-01 and to Arkema/ANR INDUSTRIAL CHAIR “HOMERIC” ANR-13-CHIN-0002-01. Ilias Iliopoulos (PIMM) and Michel Cloitre (MMC) are sincerely and warmly thanked for enlightening discussions.   REFERENCES:1. T. Soulestin, V. Ladmiral, F. Domingues Dos Santos, B.  Améduri, Progr. Polym. Sci. 72 16-60 (2017)2. F. Bargain, D. Thuau, P. Panine, G. Hadziioannou, F. Domingues Dos Santos, S. Tencé-Girault, Polymer 161 64-77 (2019)

https://sam.ensam.eu/bitstream/10985/23401/2/PIMM_EPF_2019_TENCE-GIRAULT.pdf

Crystal-Crystal transitions in poly(VDF-ter-TrFE-ter-CTFE): Influence of CTFE termonomers

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Hal-Diderot

Oskar Bordeaux

HAL Descartes

SAM : Science Arts et Métiers