STUDY OF THE OPTICAL PROPERTIES OF POLY (METHYL METHAACRYLATE) (PMMA) DOPED WITH A NEW DIARYLETHEN COMPOUND

The optical characteristics of poly (methyl methacrylate) (PMMA) films doped with4(5-{2-[5-(4-Cyanophenyl)-3-methylthiophen-2-yl]-3,3,4,4,5,5-hexafluorocyclopent 1-en-1-yl}-4-methylthiophen-2-yl) benzonitrile (I) were studied . The polymer films were prepared using solution casting technique, different concentrations (0, 2.0, 4.0 and 6.0 wt %) of the dopant ( I) were used and the optical properties of the prepared films were investigated. The optical absorption spectra of these films in the wavelength range from 190-890 nm were measured to investigate the influence of I on the optical properties of PMMA. The results showed that Energy gap (Eg opt ) of the polymer films decreases with increasing I concentration. The absorbance, absorption coefficient, extinction coefficient, finesse coefficient, refractive index, parts dielectric constant (real and imaginary) and optical conductivity of the prepared PMMA films were found to be increased with increasing the concentration of I. The indirect optical band gap for the pure and the doped PMMA films were estimated to be about 2.6, 2.8, 3, and 3.2eV for indirect allowed transition , whereas the indirect forbidden band gaps were determined as 2.5, 2.6, 2.7 and 3.2 eV with increase( I) contents, respectively.