Surface functionalization with phosphazene substrates. Part II. Theoretical and experimental investigations of the interactions of hexachlorocyclophosphazene with hydroxylated silicon-based surfaces

The interaction of hexachlorocyclophosphazene (HCCP) with the hydroxylated silicon-based surfaces is studied by a combination of XPS experimental analysis and theoretical ab initio simulations, including the estimate of the energy barriers via CI-NEB method to determine the minimum energy reaction paths. Several possible, stable chemisorbed configurations are found to exist, whose structural, energetic, and electronic properties have been analyzed in detail. The theoretical results are in good qualitative agreement with available experimental data. In particular, we get indications that water plays a crucial role in the surface functionalization with HCCP, although the presence of a suitable solvent (e.g. tetrahydrofuran, THF) seems to be essential.