The characteristic near-field spectral signature of polymers can be used to analyze polymer blends. The topography image (gray) of a PMMA/PS polymer blend already exhibits the phase separation of the structure, but does not allow to identify the materials. The near-field image (color) recorded at 1750cm^-1 reveals a pronounced contrast between the matrix and the inclusions. A control image at 1732cm^-1 verifies the true near-field optical contrast as no predominant contrast can be observed at this frequency. Comparison of the blends near-field spectral signature with model calculations for PMMA and PS  in the spectral regime between 5.5 and 6µm wavelength allows to identify the inclusions as PS and the matrix consisting of PMMA. The results show neaSNOMs potential for quantitative chemometry based on near-field infrared vibrational fingerprints with a spatial resolution in the 10nm regime.

Application-Characterization-of-polymer-blends