Kinetics of Polymer Network Formation by Nitroxide-Mediated Radical Copolymerization of Styrene/Divinylbenzene in Supercritical Carbon Dioxide

The kinetics of nitroxide-mediated dispersion copolymerization with crosslinking of styrene (STY) and divinylbenzene (DVB) in supercritical carbon dioxide (scCO2) is addressed experimentally. 2,2,6,6-Tetramethylpiperidinyl-1-oxy (TEMPO) and dibenzoyl peroxide (BPO) were used as nitroxide controller and initiator, respectively. A high-pressure cell with lateral sapphire windows at 120 °C and 207 bar was used to carry out the polymerizations. The nitroxide-mediated homopolymerization (NMP) of STY, as well as the conventional radical copolymerization (FRC) of STY/DVB, at the same conditions were also carried out as reference and for comparison purposes. The effect of nitroxide content on polymerization rate, evolution of molecular weight averages, gel fraction, and swelling index was studied.

Emerging application of robust data envelopment analysis for optimization of graft copolymerization of poly(2-hydroxyethyl methacrylate) to Tamarindus indica seed polysaccharide

A newer application of data envelopment analysis (DEA) model with robust data envelopment analysis (RDEA) was presented for optimization of reaction variables of graft copolymerization of 2-hydroxyethyl methacrylate (HEMA) to Tamarindus indica seed polysaccharide (TSP). It helped to find out the most appropriate reaction conditions and variables (concentrations of HEMA and reaction initiator; temperature and time duration) for copolymerization. The data generated through the experimental work has been analyzed and indexed to predict the maximum %grafting. Sensitivity analysis was performed to check robustness of efficiency scores of CCR DEA efficient samples and a comparative analysis of the CCR DEA and RRDEA efficiency score has been done. The data obtained via real-time experiments and data predicted using computational modelling predictions were found to be in close vicinity.

Modeling of RAFT polymerization of MMA in supercritical carbon dioxide using the PC-SAFT equation of state

The PC-SAFT equation of state was applied to the study of RAFT polymerization of methyl methacrylate in supercritical CO₂.

Modeling and Observer-Based Monitoring of RAFT Homopolymerization Reactions

Reversible addition–fragmentation chain–transfer (RAFT) polymerization of methyl methacrylate (MMA) is modeled and monitored using a multi-rate multi-delay observer in this work. First, to fit the RAFT reaction rate coefficients and the initiator efficiency in the model, in situ 1 H nuclear magnetic resonance (NMR) experimental data from small-scale (<2 mL) NMR tube reactions is obtained and a least squares optimization is performed. 1 H NMR and size exclusion chromatography (SEC) experimental data from large-scale (>400 mL) reflux reactions is then used to validate the fitted model. The fitted model accurately predicts the polymer properties of the large-scale reactions with slight discordance at late reaction times. Based on the fitted model, a multi-rate multi-delay observer coupled with an inter-sample predictor and dead time compensator is designed, to account for the asynchronous multi-rate measurements with non-constant delays. The multi-rate multi-delay observer shows perfect convergence after a few sampling times when tested against the fitted model, and is in fair agreement with the real data at late reaction times when implemented based on the experimental measurements.