Acrylamide inverse miniemulsion polymerization: in situ, real-time monitoring using nir spectroscopy

Abstract

-In this work, the ability of on-line NIR spectroscopy for the prediction of the evolution of monomer concentration, conversion and average particle diameter in acrylamide inverse miniemulsion polymerization was evaluated. The spectral ranges were chosen as those representing the decrease in concentration of monomer. An increase in the baseline shift indicated that the NIR spectra were affected by particle size. Multivariate partial least squares calibration models were developed to relate NIR spectra collected by the immersion probe with off-line conversion and polymer particle size data. The results showed good agreement between off-line data and values predicted by the NIR calibration models and these latter were also able to detect different types of operational disturbances. These results indicate that it is possible to monitor variables of interest during acrylamide inverse miniemulsion polymerizations.

How to Formulate a Stable and Monodisperse Water-in-Oil Nanoemulsion Containing Pumpkin Seed Oil: The Use of Multiobjective Optimization

“…Despite the fact that some authors claim that a stable emulsion can be obtained without electrolytes in the emulsion and/or that the addition of salt (NaCl) or sodium phosphate buffer destabilizes the emulsion (Su et al, 2008), it is well known that the stability rating of primary W/O emulsions is markedly affected by the addition of electrolytes in the inner aqueous phase (Moguet et al, 2001, Srinivasan et al, 2000. Actually, salt is considered to be a costabilizer, a lipophobe that builds-up the osmotic pressure to counterbalance the Laplace pressure, and consequentially stabilizes emulsions against diffusional degradation known as Ostwald ripening (Capek, 2010, Colmán et al, 2014, Landfester, 2006. Therefore, the addition of an osmotic agent that cannot interdiffuse between two droplets, and the use of an appropriate hydrophobic surfactant, could both be essential for preparation of stable and monodisperse water-in oil emulsions, with droplet sizes ranging from 50 to 500 nm, well known as inverse miniemulsions (Landfester, 2000, Landfester, 2003.…”

Inverse emulsion free‐radical polymerization of acrylamide terpolymer for enhanced oil recovery application in harsh reservoir conditions

“…In support, Qisheng et al via Quantum Mechanics Density Functional Theory concluded that structural modifications of polyacrylamides by introducing functional groups such as AMPS and VP would improve the polyacrylamide stability . Many reports are related to inverse emulsion polymerization of acrylamide ; Mohsin et al obtained a homopolymer of AAm through inverse emulsion by using a polymeric surfactant which also contain sorbitan monooleate as emulsifier ; while Wang et al, synthesized a polymer based on AAm and AMPSNa using triton X‐100 as emulsifier. These authors determined that the polymer viscosity remained constant for one month at 85°C and at water salinity of 32,000 mg/L .…”

Monitoring of Generation and Stability of Droplets in Miniemulsion Polymerizarion Using the Near‐Infrared Spectroscopy

“…The formation of stable nanodroplets occurs by mixing the organic phase (monomer and costabilizer) with the continuous aqueous phase under the influence of shear in the presence of a costabilizer. Droplet size reduction continues until an equilibrium is attained between the rates of droplet rupture and coalescence . This process forms a miniemulsion that is thermodynamically instable, but kinetically metastable.…”

“…News tools for monitoring the process of the particle generation and stabilization would provide important information about the evolution of the number and nature of the droplets in the reactor, and would contribute to a better understanding of the miniemulsion processes. Because of its versatility and speed in the evaluation of different properties in chemical process, near‐infrared (NIR) spectroscopy has been used with success in the monitoring of polymeric systems . The NIR region from 4000 to 10 000 cm −1 covers the overtones and the combination bands of CO, CH, OH, and NH groups.…”

“…In this context, calibration techniques are needed to correlate NIR data with the properties that we wish to follow. Such techniques involve the use of algebra of matrices and statistical tools, including principal component analysis (PCA), principal component regression (PCR), and partial least squares (PLS), the latter being the most widely used method . The proper selection of the spectral region for PLS calibration is crucial to correlate the sample composition with the spectra data …”