Quantitative Analysis of Styrene Monomer in Styrene/Butadiene Latexes Using Raman Spectroscopy

Abstract
A simple rapid method has been developed for the quantitative analysis of styrene monomer in butadiene/styrene latexes using Raman spectroscopy. The latex samples were sealed in capillary tubes and scanned under high resolution conditions using a Spex Ramalog 1401 with a Spectra Physics 2 W argon ion laser. The Raman method involves ratioing the olefinic C=C (1632 cm−1) band of styrene monomer to the trans 1:4 C=C (1668 cm−1) band of butadiene in the butadiene/styrene polymer. Typical samples were found to have as low an unreacted styrene concentration as 0.7 wt. %. Reproducibility between samples was found to be within 0.1%. The values of residual styrene obtained by the Raman technique agreed within 0.25% with those obtained by liquid chromatography.