The application of ESCA to structure and bonding in selected polymer systems

Abstract

The core levels of a series of eighty-three homopo1ymers have been studied by ESCA. Comparisons of the experimentally determined core level binding energies with theoretical calculations within the CNDO/2 SCF MO formalism have been made on the C(_ls), and 0(_ls) core levels for the oxygen containing polymers in the series. A comparison of the ground state potential (GPM) and relaxation potential (RPM) models on a series of six model compounds is given. Compilations are given of binding energies of C(_ls), 0(_ls), N(_ls), C1(2p) , S(_2p) , Si(_2p) and Br(_3d) levels for typical structural features of common occurrance in polymer systems. Electron mean free paths as a function of kinetic energy have been measured by the substrate-over layer technique for in-situ polymerized films of po1yparaxy1y1enes. The results are compared with previous estimates of mean free paths available in the literature for organic materials. Comparison is also drawn with corresponding experimental data for typical metals and semi-conductors and it is shown that organic polymers fit into a consistent picture which may be rationalized on the basis of existing theory. A systematic series of experiments are described on the ESCA examination of 1) a series of [2.2] paracyclophanes, in an attempt to define isomeric differences in the structure and bonding properties of these systems; 2) a series of aliphatic aromatic and fluorine containing polycarbonates which Include theoretical and experimental data pertaining to the absolute and relative binding energies for C(_ls), 0(_ls) and F(_ls) core levels; 3) sample charging phenomena in the ESCA examination of thick insulating samples; 4) polymer/metal interfaces on a series of transition metals: molybdenum, tungsten, niobium and zirconium. Radio frequency plasmas excited in inert gas (argon) and active gas (oxygen) were used to "ablate" and "ash" the polymer over layers to approach the Interface for ESCA investigation of both the carbon type over layer and metal/metal-oxide substrate; In conclusion 5) a polymeric by-product of the direct fluorination of benzene in an attempt to determine the structure and composition of the po1ymer .