Structure and properties of ferroelectric copolymers of poly(vinylidene fluoride)

Structure, phase transition and electric properties of poly(vinylidene fluoride-trifluoroethylene) copolymer studied with density functional theory

“…The results show that the introduction of TrFE into VDF is in favor of forming trans-conformation copolymer (or b-phase). This might be the reason that the copolymers are able to crystallize into ferroelectric b-phase at room temperature but PVDF homopolymer is not [42,43]. Obviously, the decrease of energy of b-chain and the decrease of curvature of a-chain ( Fig.…”

“…The larger proportion of bulky trifluorine atoms in the PVDF prevents the molecular chains from accommodating the a-chain (or tgtg 0 , where g refers gauche and t refers trans, and a prime ( 0 ) in g refers the dihedral angle being opposite to the g conformation with respect to the reference plane t) conformation. Therefore, the copolymer crystallizes directly at room temperature into a ferroelectric b-phase (or ttt, where t also refers trans) [42,43] that possesses a polar unit cell (similar to the b-phase of PVDF homopolymer), and the copolymer can be electroprocessed into a piezoelectric material immediately after crystallization.…”

Ferroelectricity and molecular dynamics of poly(vinylidenefluoride-trifluoroethylene) nanoparticles

“…P(VDF-TrFE) copolymers with TrFE content higher than ≈ 10 % crystallize in a ferroelectric phase [9,10], either monoclinic or orthorhombic depending on molar ratio, which is similar to the ferroelectric β-crystalline phase of PVDF [4]. This ferroelectric phase is stable at room temperature and exhibits a first order phase transition to a paraelectric one, which is hexagonal, as temperature increases [11]. The transition temperature, frequently referred to as Curie temperature, increases with TrFE content [11].…”

Solid‐state 1H → 19F/19F → 1H CP/MAS NMR study of poly(vinylidene fluoride)

“…Although five such forms have been reported, two major crystalline ones, namely the˛-andˇ-polymorphs, frequently exist in as-polymerized powder. 1,2 The chains of thę -form have the tg C tg conformation, whereas those in thě -form have the all-trans conformation. Although solutionstate 19 F NMR of PVDF dissolved in dimethyl-d 6 sulfoxide has been investigated by several workers, 3 -7 high-resolution solid-state NMR studies have been limited until recently because of the existence of two abundant spin baths, fluorine and hydrogen.…”