Pulsed laser studies of cationic reactive surfactant radical propagation kinetics
Rooney, Thomas R.
Hutchinson, Robin A
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Pulsed laser polymerization coupled with size exclusion chromatography (PLP-SEC) was implemented to study the micellar radical homopropagation kinetics of cationic surfmer, polycaprolactone choline iodide ester methacrylate (PCLnChMA with n = 2 average polyester units), at concentrations of 5, 10, and 20 wt% in aqueous solutions at 25, 50, 70, and 85 °C. PCL2ChMA can propagate in both aqueous and compartmentalized phases, with the relative importance of the two reaction loci changing with temperature. As the corresponding saturated macromonomer concentration, [M], inside the growing polymeric micelles cannot be easily determined, only the product of propagation rate coefficient (kp) and [M] are measured by PLP-SEC; at 25 °C, a minimum kp of 863 ± 95 L mol−1 s−1 is estimated assuming bulk [M]. (Macro)monomer composition drifts for batch acrylamide (AM)/PCLnChMA micellar copolymerizations in D2O at 50 °C are well represented by the apparent reactivity ratios rAM = 0.31 ± 0.03 and rPCL3ChMA = 8.79 ± 0.38.