High resolution monochromated X-ray photoelectron spectroscopy (XPS) studies on novel biodegradable poly(ortho esters) prepared using N-methyl- and N-phenyldiethanolamine, correlated with binding energies obtained from ab initio molecular orbital methods

Abstract

High resolution monochromated X-ray photoelectron spectroscopy (XPS) was used to investigate the surface chemical structure of novel poly(ortho esters) prepared from N-methyl and N-phenyldiethanolamine (MDE and PDE), respectively. Good agreement was observed between the theoretical and experimental values for the atomic percentages and also for the carbon environments within the C1s spectra. Ab initio molecular orbital calculations were carried out to investigate the effect of local chemical environment on the C -N binding energy. Excellent agreement was observed between experimental and calculated values, provided that the nitrogen configuration in PDE was assumed to be essentially planar and in MDE was pyramidal. This apparent dependence of calculated binding energy on nitrogen configuration is particularly noteworthy and is the subject of further study.