X-ray absorption spectroscopy of polyureas and polyurethanes and their use in characterizing chemical gradients in thin-walled polyurea capsules

The carbon 1s near edge X-ray absorption spectra of several aromatic and aliphatic polyureas and polyurethanes are reported and their spectral features are assigned. An example is given of the application of these spectra as references for quantitative chemical mapping by scanning transmission X-ray microscopy (STXM) which is being used for analytical feedback in the development of controlled release polyurea capsules with chemical structuring across the capsule wall.