Microstructural, thermal and electrical properties of PFO/PMMA composite films

In this study, a dielectric polymer PMMA (poly(methyl methacrylate) is doped with the light-emitting polymer PFO (poly(9,9'-di- n -octylfluorenyl-2,7-diyl) by the solution casting method. The composite films were subjected to different characterizations such as UV–visible and fluorescence spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry, dielectric analysis and conductivity measurements. UV–visible and fluorescence spectroscopy reveal that 1 wt% of PFO in PMMA is the critical composition for the composite films as it has the maximum intensity of emission as evidenced in fluorescence spectra. The XRD and FTIR analyses confirm the complex formation between PMMA and PFO, and the TGA affirms it. The measurements of dielectric parameters, ac conductivity and ac impedance clearly affirm the critical composition of 1 wt% of PFO in PMMA as a percolation threshold.