Termination and Transfer Kinetics of Acrylamide Homopolymerization in Aqueous Solution

Abstract

The single pulse−pulsed laser polymerization−electron paramagnetic resonance (SP−PLP−EPR) method affords the detailed kinetic analysis of acrylamide polymerization in aqueous solution. Highly time-resolved SP− PLP−EPR experiments for 10 and 20 wt % AAm were first carried out at −5°C, where only secondary propagating radicals (SPRs) occur. In a second step, the time evolution of midchain radicals (MCRs), produced from SPRs by backbiting, was measured at higher temperatures. The termination kinetics, including chainlength dependent termination of SPRs, the backbiting rate of SPRs, and the propagation rate of MCRs were determined. The rate coefficients from SP− PLP−EPR in conjunction with the known propagation rate coefficient of SPRs, enable the simulation of the kinetics and product properties of AAm radical polymerizations in aqueous solution.

Photopolymerization of acrylamide in the very low monomer concentration range

“…The slight decrease in the polymerization rate with conversion agrees more with the trend of the ratio k p /k t obtained for various water-soluble acrylic monomers (acrylic acid, methacrylic acid, acrylamide and methacrylamide) assined to the chain transfer events [7,13] and some references mentioned herein. Herein the polymerization process is accompanied by the transformation of a secondary propagating radical (sPR, k p s ) into a tertiary midchain radical (MCR, k p t ).…”

“…Figure 2 shows that the polymerization rate slightly decreases with conversion in the interval 2. Indeed the ratio k p /k t obtained for various water-soluble acrylic monomers (acrylic acid, methacrylic acid, acrylamide and methacrylamide) corrected with the chain transfer steps was observed to slightly decrease with conversion [7,13] and some references mentioned herein. The observed decrease in R p with conversion in interval 2 points out on the increased termination.…”

Measuring and modelling the peculiarities of aqueous‐phase radical polymerization

“…[26,33] Pulsed-laser polymerization techniques have also been applied to the study of termination kinetics of water-soluble monomers in aqueous solution. [40] The data shown were measured at 200 MPa to improve IR signal quality, but similar trends have been observed for MAA, [41] AA, [42,43] and AAm [44] at both high and low pressures. [39] As viscosity can vary significantly with composition of monomerwater mixtures, so too does the low-conversion value of k t,ss .…”

Experimental and Modeling Study of Acrylamide Copolymerization with Quaternary Ammonium Salt in Aqueous Solution

“…The values of the reactivity ratios corresponding to AAm homopolymerization have been estimated from unpublished data of the individual rate coefficients of k p,AA , 40 k bb,AA , and k p,AA T . 41 Accordingly, t AA = 0.299 × 10 −3 (parameter A 8 ) and b AA M = 0.356 × 10 −3 (parameter A 4 ) at 50°C. Moreover, focusing on the final expressions of the reactivity ratios in Table 2, a correlation between each pair of parameters A n and B n applies.…”