Optical and electronic characterization on polymeric membranes

Abstract

This work is dedicated to the optical and electronic characterization of poly(ethylene terephthalate) (PET) membranes, which are extensively used in many practical applications. Spectroscopic ellipsometry (SE) from 1.5 to 6.5 eV was applied to probe the dielectric function ( ε( ω)) of industrially supplied PET membranes and to reveal their optical anisotropy. Two characteristic features were observed at ∼5.0 and 6.1 eV, attributed to electronic transitions occurred in specific chemical bonds of the PET macromolecule. Through the appropriate fitting analysis it was obtained the geometrical structure of the membrane; consisting of a thick amorphous layer with a crystalline-like layer on top of it, formed during treatment processes. Using Fourier transform infrared (FT–IR) SE it was also extracted the spectral dependence of the ε( ω) in IR energy range by taking into account the contribution of the PET’s vibrational modes, and this it was found to be in an excellent agreement with the SE results.