Fluoropolymer Dielectrics

Complex Dynamics of a Fluorinated Vinylidene Cyanide Copolymer Highlighted by Dielectric Relaxation Spectroscopy

“…According to the theory of Onsager, this parameter is proportional to the effective number of dipoles aligned with the external applied field: where μ j is the dipole moment associated with the molecular group j , ∑ j N j is the total volume concentration of molecular dipoles, and g k is the Kirkwood factor that takes into account the relative molecular orientation . From the plateau of ε′ at 355 K ≤ T ≤ 393 K (Figure S1) the dielectric increment Δε T appears relatively small, with a value around unity at T g , and as such it is compatible with the similarly small molecular dipole moment μ = 1.34 D calculated for the trifluoro­ethoxy­carbonyl side chain of poly­(TFEMA) . The overall dynamic scenario for the different relaxations is shown in Figure , also including a few data from literature for poly­(TFEMA) and for the parent unfluorinated poly­(EMA). − …”

“…The 3D arrangement associated with the two types of repeat units in the VCN–TFEMA–VCN trimer has been obtained by DFT simulation (see Figure ). The moduli of the dipole moments have been reported to be between 4.0 and 4.5 D for the highly polar VCN repeat unit and 1.34 D for the trifluoro­ethoxy­carbonyl side chain of the TFEMA repeat unit.…”