Modifications in optical and structural properties of PMMA/PCTFE blend films as a function of PCTFE concentration

- PMMA blend films with varying PCTFE concentrations (1-5 wt%) were prepared.
- Nanocrystalline nature of PMMA is preserved in spite of bond modifications.
- Addition of PCTFE results in improvement of overall crystallinity of the films.
- Urbach energy shows a decreasing Disorder upon inclusion of more PCTFE molecules.
- FTIR spectra show bond modifications without changing refractive index.

The poly (methyl methacrylate) (PMMA) polymer blend films were prepared by solution casting method with varying PolyChloroTriFluoroEthylene (PCTFE) concentrations (1-5 wt %). The crystallinity, bonding behavior and disorder in the films were investigated with X-ray diffraction (XRD), Fourier transform infrared (FTIR), UV-visible and ellipsometry techniques, while surface morphology was studied using Atomic force microscopy (AFM). The nanocrystalline nature of PMMA is seen to be preserved in the blends although there are clear indications of bond modifications. The addition of PCTFE results in the improvement of overall crystallinity of the films via the interaction among PMMA and degraded PCTFE molecules when the films are casted from diluted solutions. In agreement, corresponding disorder in terms of Urbach energy shows a decreasing trend upon inclusion of more and more PCTFE molecules. Micro-Raman spectra are dominated by fluorescence background, which is proposed as arising from degraded PCTFE. Supporting this, FTIR spectra also shows modifications in bonding as a function of PCTFE percentage, but this bond modification is not enough to produce refractive index variation in the sample, which is dominated by the host PMMA contribution for all the PCTFE concentrations. The study suggests the useful range of PCTFE concentration in which PMMA host properties can be modified for optimizing optical and structural properties without much degradation of PCTFE.