Improving ferroelectricity and ferromagnetism of PVDF-CoFe2O4 thick films: Effect of Ethyl acetate and Temperature

PVDF-CoFe2O4(CFO) thick membranes were synthesized by solvent casting method. The mixed organic solvents consist of N-methyl-2-pyrrolidone (NMP) and Ethyl acetate (EA), in which the mass ratios of NMP and EA (NMP:EA = 1:0, 1:1, and 1:2) and the temperature of solvent evaporation (range from 50 to 80 degrees C) has been considered. The phase structure, beta-PVDF phase content, and electrical and magnetic properties of these membranes were investigated to reveal the effect of EA addition and temperature on these properties. Results manifest that all samples showed coexistence of ferroelectric and ferromagnetic properties at room temperature. EA addition makes film more compact, which may be responsible for the differences in ferromagnetic properties. Adding EA and enhancing temperature resulted in phase transition of PVDF from alpha and gamma to beta, which contributed to membranes' ferroelectric performances. In all samples, NMP:EA = 1:2 treated at 80 degrees C exhibits the maximum beta-phase fraction and polarization (Pmax) of 87.2% and 2.398 mu C cm(-2), respectively. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48345.