In situ conversion monitoring of styrene emulsion polymerization by deconvolution of a single reference band near 1,000 cm⁻¹

Abstract

Styrene emulsion polymerization was performed in batch reactor using Raman spectroscopy for in situ monitoring of styrene conversion. The variation of the band of trigonal aromatic ring breathing at 1,000 cm−1 was analyzed in detail as a function of monomer conversion (wavenumber, integrated intensity, and half‐width at half‐maximum). The observed variation was described both qualitatively and quantitatively by a model assuming that the overall signal resulted from the addition of two close and distinct Gaussian signals, one originating from the monomer and the other one from the polymer repeat units. A reliable estimation of monomer conversion was obtained using the relative contributions of both components. The results were comparable to those obtained using the ratio of integrated intensities of the band at 1,000 cm−1 (overlapping signals of monomer and polymer) and the band at 1,631 cm−1 (signal specific to monomer). It was shown experimentally that information about monomer conversion could be obtained by applying linear model mixture to a single band of Raman spectrum, which provided an alternative method to the use of a ratio of integrated intensities.

Recent advances in linear and nonlinear Raman spectroscopy. Part XIV

“…Cui et al [ 189 ] described a real‐time Raman analysis of cleaning solution and applied it to the determination of residues in a cleaning mixture. Dropsit et al [ 190 ] demonstrated in situ conversion monitoring of styrene emulsion polymerization by deconvolution of a single reference band near 1000 cm −1 . They showed experimentally that information about monomer to polymer conversion could be obtained by applying linear modeling of the mixture to a single band of the Raman spectrum, which provided an alternative method of using a ratio of integrated intensities.…”

In-line Monitoring of Microgel Synthesis: Flow versus Batch Reactor

“…In-line measurements via Raman spectroscopy are nondestructive, need no preparation, and are only slightly affected by scattering of water below a Raman shift of 2750 cm –1 . Thus, Raman spectroscopy represents an established process analytical technology (PAT) tool for various applications in polymerization, most prominently in emulsion polymerization − and precipitation polymerization. , …”

Inline Raman Spectroscopy of an Emulsion Copolymerization in an Industrial Pilot Plant Using Indirect Hard Modeling

“…In [9], the polymerization of styrene using bulk, emulsion and mini-emulsion polymerization is followed using Raman spectroscopy by computing the ratio between the area of the Raman peaks of the C=C double bond band and the aromatic band. Dropsit and coworkers [10] monitor the conversion of a styrene emulsion polymerization by analyzing the aromatic ring breathing at 1000 cm -1 as the contribution of styrene monomer and styrene polymer. These works use either peak integration methods, i.e., analyzing single peaks or PLS regression.…”