The dielectric and polarization behavior of polyurethane-based polycarbonate diols with different content levels of fluorinated hard segments

A novel series of polyurethane-based polycarbonate diols containing fluorinated hard segments in the main chain (FPU) were synthesized using a prepolymer method. The fluorinated hard segment content was varied to study the effects on the dielectric and polarization behaviors under an applied electric field (P-E loop). The addition of a fluorinated chain notably improved the polarization via an induced dipole moment in the PU films and higher dielectric constant, including allowing the relaxation peak to move to a lower frequency. Paraelectric loop behavior was observed with thinner loops as the fluorinated group content was increased. The nature of the solvent used for the synthesis affected the H-bonding capabilities and fluorinated group content. FPU synthesized in dimethylformamide showed a higher dielectric constant than that synthesized in dimethylsulfoxide due to its higher fluorine content.