New insight on the structural trends of polyphosphate coacervation processes

In this study new compositions of polyphosphate coacervates were obtained with the ions Ni2+ and Co-2. Samples of the glassy systems were prepared with proportions p/M+2 varying between 0.5 and 10. The qualitative and quantitative description of the first coordination shells of the transition metal were obtained through extended X-ray absorption fine structure spectroscopy (EXAFS) analysis, performed at the Ni2+ and CO2+ K-edges. An analysis of the symmetric stretching vibrations of terminal P-O-t and bridging P-O-b groups performed through Raman spectroscopy revealed the different phases of the coacervation process in terms of bond strengths and corroborates the EXAFS results. The results obtained permitted a detailed structural description of these materials as well as the role played by the metallic ions on the coacervation process.