Temperature Sensitivity of Flexible Co3O4/PVDF Dielectric Nanocomposites

Temperature-sensitive and flexible nanocomposite films are prepared by doping a poly(vinylidene fluoride) (PVDF) matrix with cobalt oxide (Co 3 O 4 ) nanoparticles. The structural and morphological characterization, dielectric properties, and conductivity of the Co 3 O 4 /PVDF nanocomposites are then systematically investigated. The nanocomposite film loaded with 10 wt.% Co 3 O 4 displays dielectric permittivity of 37 at 1 kHz, which is about 274% higher than that of pristine PVDF (13.5 at 1 kHz). The dielectric constant of the 10 wt.% Co 3 O 4 /PVDF nanocomposite as a function of absolute temperature can be fitted as \( T = 26.62 \times \ln \left( {(\varepsilon_{r} - 40.595)/1.335 \times 10^{ - 5} } \right)\) over a range of 300–423 K at 1 kHz. This fitting formula may provide important reference values for the design of flexible temperature sensors. The temperature coefficient of the dielectric constant (at 1 kHz) for the 10 wt.% Co 3 O 4 /PVDF nanocomposite film is 0.94% K −1 within a range of 350–423 K, and conductivity of about 5.78 × 10  −5  S / cm is achieved at 383 K, which is four orders of magnitude larger than that for the pristine PVDF (3.9 × 10 −9  S / cm). These results show that the addition of Co 3 O 4 nanoparticles in PVDF matrix significantly improves the dielectric constant and temperature sensitivity of the composites. Thus, the Co 3 O 4 /PVDF nanocomposites show potential application prospects in miniaturized and flexible temperature sensors.