Non-destructive method for the quantification of the average particle diameter of latex as water-based emulsions by near-infrared Fourier transform Raman spectroscopy

Vibrational spectroscopy is utilized to characterize compounds, but it has never been applied to quantitative morphological analysis of polymers in a mass. By using near-infrared Fourier transform Raman spectroscopy coupled with multivariate data analysis, the average particle diameter of macroscopic size in water-based latex emulsions was successfully quantified with correlation coefficients >0.95, both in calibration (known samples, n = 36) and in prediction (unknown samples, n = 11) against conventionally measured values obtained by the dynamic laser diffraction scattering method. This method is valid for samples of various monomer compositions together with various fluorescence and Rayleigh scattering intensities causing different background levels in the spectra.