Indian Journal of Pure & Applied Physics Vol. 54, February 2016, pp. 105-110 Study of refractive index dispersion and optical conductivity of PPy doped PVC films Vaishali Bhavsar 1 * & Deepti Tripathi 2 1 SAL Engineering and Technical Institute, Ahmedabad 380 060, India 2 Department of Physics, School of Sciences, Gujarat University, Ahmedabad 380 009, India Received 1 March 2015; revised 12 August 2015; accepted 26 October 2015 The refractive index (n), dispersion and optical conductivity (σ opt ) of undoped and PPy doped PVC films have been studied. The PPy doped PVC films are prepared by solution cast technique with various concentrations of PPy (6% to 20%) in PVC. The optical absorption spectra of these films have been recorded in the wavelength range 400-900 nm at room temperature. Optical parameters such as refractive index (n), extinction coefficient (k), real (εʹ ) and imaginary (εʹʹ ) parts of complex permittivity, optical conductivity (σ opt ) and infinitely high frequency dielectric constant (ε ∞ ) have been evaluated. It is seen that the optical properties of PVC have been affected on doping it with PPy. The average refractive index (n), infinitely high frequency dielectric constant (ε ∞ ) and optical conductivity (σ opt ) of the samples exhibit a nonlinear compositional dependence as observed in many amorphous materials. Keywords: Polypyrrole, Polyvinylchloride, Refractive index, Optical conductivity, Infinitely high frequency dielectric constant 1 Introduction Polymers in the preset era are the materials of great interest because of their low cost, easy processability, low weight, high quality surfaces and easy fabrication of thick and thin films 1 . Study of the optical constants such as refractive index (n), extinction coefficient (k), real (εʹ) and imaginary (εʹʹ) parts of complex permittivity, optical conductivity (σ opt ) of polymer films is important for designing new materials. Study of optical constants of the material leads to their possible use in many technological applications 6 . Refractive index is an important optical parameter for designing prisms, optical windows and optical fibers 2 . Moreover, changes in the refractive index (n) of films are important for controlling optical properties of the material 1 . The doping of conducting polymers like polypyrrole, polyaniline, polythiophene etc in insulating polymers like polyvinylchloride, polymethylmethacrylate, polycarbonate and their blends has been an important area of research to produce conducting polymer composites exhibiting enhanced electrical, optical and mechanical properties that constituent materials may not exhibit. Rawat et al. 1 investigated optical band gap of thin films of PVP and PAM films Deshmukh et al. 2 studied the UV-VIS absorption spectra for different compositions of PANI doped PVC-PMMA thin films for wavelength range 450-1000 nm. The effects of % doping of PANI on these various optical parameters have been studied Wadatkar et al. 3 studied complex optical properties of polyindole as synthesized through chemical route. Optical properties of samples with different concentration of FeCl 3 as oxidant have been studied. Nemade et al. 4 investigated complex optical properties of V 2 O 5 -P 2 O 5 -B 2 O 3 -Dy 2 O 3 glass system. Polypyrrole (PPy) is an intrinsic conducting polymer which can be made to have conductivities up to 1000 S/cm, furnishing its versatile applications in batteries, electronic devices, electrochromic devices, optical switching devices, sensors and so on. In recent years, polyyrrole (PPy) is extensively preferred in research field and has been focus of many studies over other conducting polymers because of its high chemical and air stability and ease of preparation. But it is insoluble, infusible and lacks essential mechanical strength. Attempts to overcome these drawbacks have led to numerous researches on synthesis of PPy. Among them a significant approach is to prepare blends or composites of PPy with other insulating polymers. This combination is an important alternative to obtain new polymeric materials with new design properties. Blending conducting polymers with insulating matrix gives a —————— *Corresponding author (E-mail: vaishali.b.bhavsar@gmail.com)