The Chemical Interaction of Organic Materials with Metal Substrates. Part II: FT-IR Studies of Organic Phosphate Films on Steel

Abstract

Reflection-absorption spectroscopy at grazing incidence has been shown to be a useful tool for investigation of thin organic films on gold and steel substrates. No artifacts related to the technique were identified for films thinner than 250 Å. The spectra obtained for films of an organic phosphate on polished steel substrates are consistent with reaction of the organic phosphate with the steel to produce a metal salt. The organic phosphate studied in this work was the reaction product of the diglycidyl ether of bisphenol-A (DGEBA), and comprised the mono- and diphosphoric acid adducts of DGEBA. The spectrum of the organic phosphate films formed on steel was indicative of a specific complex rather than the random product formed by bulk precipitation: the P-O stretching vibrations occurred as a pair of bands, while the spectrum of the salt formed from solution contained but a single band. No chemical interaction of the organic phosphate with the gold substrate was observed. The spectra have relative intensity changes with thickness which indicate the presence of ordering for the thinnest films studied.