Superior optical and dielectric properties of ultrasonic-assisted solution-cast prepared PMMA/MMT nanocomposite films

Poly(methyl methacrylate) (PMMA) and montmorillonite (MMT) nanoclay based PMMA/MMT nanocomposite films were prepared by solution-cast (SC) and ultrasonic-assisted SC (USA-SC) methods, and characterized for structural, thermal, optical, and dielectric properties. The x-ray diffraction patterns evidenced that the amount of MMT exfoliated nanoplatelets and tactoids in the nanocomposites are significantly affected by the preparation methods. Differential scanning calorimetry thermograms showed lowering of glass transition temperature of these nanocomposites as compared to the neat polymer matrix. The ultraviolet-visible spectroscopic measurements explained that the SC prepared PMMA/MMT films have high absorbance in comparison to host matrix which further enhanced when the film thickness was increased. However, in comparison to the SC prepared nanocomposite films, the USA-SC prepared films have low absorbance in the visible region which remained independent of the film thickness. Each nanocomposite film exhibited two different energy bandgaps which confirm their use as multifunctional bandgap tuner in optoelectronic devices. The dielectric relaxation spectroscopy in the frequency range from 20 Hz to 1 MHz revealed that the USA-SC prepared PMMA/MMT film has about nine per cent increase of dielectric permittivity at all the frequencies without alteration in dielectric loss when compared with the PMMA film, confirming its great potential as nanodielectric for advances in flexible microelectronic device technology.