The application of ESCA to structure and bonding with particular reference to synthesis and surface modification of polymers

Abstract

Electron mean free paths as a function of kinetic energy have been measured by the substrate overlayer technique forin-situ polymerised films of polyparaxylylene, using a Ti(_ka1,2) (hv = 4510 eV) X-ray source. The results are compared with those previously reported at lower kinetic eneraies using Mg(_ka1,2) (1254 eV) and A1(_ka1,2) (1487 eV) photon sources ESCA is used to study structure, bonding and reactivity of polymeric materials, in particular those prepared by R.F. (radio-frequency), "glow discharge techniques", (plasma polymerisation) .Plasma polymerised films of perfluoropyridine have been investigated for a range of operating parameters, in both free-standing and in-situ reactors. A comparison of the stoichiometries and rates of deposition has been drawn with plasma polymers produced under comparable conditions from perfluoro and pentafluorobenzenes. Ultra thin polymers produced by plasma techniques from three isomeric perfluorinated diazines (pyrazine, pyrimidine and pyridazine) have been investigated. The polymer produced from the 1,2-diazine is discussed in some detail. A combination of ESCA and microanalytical studies show that the C:F and C:N stoichiometrics are closely similar to those for the starting monomers, over a range of operating parameters. The surface hydrolysis of these polymers with water as a function of time has been studied. The rates of polymer deposition are discussed as a function of the composite parameter W/FM. The rates of deposition reveal distinctive differences between the isomeric diazines and those of plasma polymer films for isomeric fluorinated benzenes. Laminate films based on LDPE and PET adhesively bonded with polyurethane adhesives have been investigated by ESCA. The change of surface chemistry of these films has been compared with the non-laminated base polymer of LDPE and PET. Migration and segregation phenomena in the laminates has been investigated. ESCA has been used to investigate the surface chemistry of heat treated LDPE (low and high-slip agent) and PET. The results indicate that thermally promoted reactions at the surface may well be different than those in the bulk.