Insights into the physico-chemical behavior of CoCl2/polyimide hybrid materials

Abstract

Hybrid fluorinated polyimide materials have been obtained by incorporation of various quantities of cobalt(II) chloride (CoCl2) into polyimide matrix. Polycondensation reaction of equimolar amounts of 4,4′-diamino-3′3′-dimethyldiphenylmethane and 2,2′-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride has been carried out to produce in the first stage a polyamidic acid solution in which CoCl2 × 6H2O has been placed. Further thermal treatment of this system led to the corresponding imide structure filled with the halide salt. An exhaustive study was directed to the influence of Co2+ ions on the modified polyimide behavior as a function of its surroundings. To survey the functional properties of as-obtained Co2+-containing polyimide systems, several techniques such as FTIR, UV-vis and broadband dielectric spectroscopy, differential scanning calorimetry, and thermogravimetric and scanning electron microscopy were employed. A special concern was directed to the study of the optical properties induced by the addition of CoCl2 into polymer solutions and films. The magnetic response of the polyimide was investigated in correlation with the salt quantity embedded in the PI film. The variation of the real and imaginary parts of the hybrid films’ dielectric permittivity was registered in a broad frequency and temperature range, from 10 to 106 Hz and from −130 to 230 °C, respectively.