On-line monitoring and composition control of the emulsion copolymerization of VeoVA 9 and butyl acrylate by Raman spectroscopy

The batch and semi-continuous emulsion copolymn. of Bu acrylate and vinyl neononanoate (VeoVA 9) were monitored by remote online Raman spectroscopy. Monomer concns. were calcd. in real-time by a classical least squares (CLS) approach using the vinyl regions of the Raman spectra. During the batch copolymn., conversion and copolymer compn. calcd. from online data showed good agreement with off-line gravimetry and NMR results, indicating that the CLS procedure enables the calcn. of individual monomer concns. and online characterization of the copolymer formed. Real-time anal. of the data enabled control of the copolymer compn. by suggesting how one of the comonomers should be added in a semi-continuous polymn. NMR and gradient polymer elution chromatog. corroborated the Raman results for the copolymer compn. Further, only at high conversions (>80%) monomer partitioning influences the copolymn. mechanism, since both monomers have low soly. in water. Thus, Raman spectroscopy is well suited as online monitoring technique in emulsion copolymn. processes. [on SciFinder (R)]