Micellar Aqueous Phase Polymerization of Acrylamide

Abstract

The kinetics of aqueous phase radical polymerization of acrylamide initiated by ammonium peroxodisulfate (APS) and 2,2 -azobisizobutyronitrile (AIBN) were studied in the presence of the non-ionic hydrophilic Tween-20 and hydrophobic Tween-85. The polymerization rate vs. conversion curve is described by a curve with two or three rate intervals and the maximal rate is located at medium conversion. This behavior strongly deviates from the kinetic model of the ideal solution polymerization with the steady-state kinetics at low and medium conversions. On the contrary, the present data indicate the kinetics typical for the transparent heterogeneous-micellar or microemulsion polymerization. The associates of polyacrylamide and acrylamide play the role of active particles. Indeed, the light scattering measurements confirmed the presence of polyacrylamide nanoparticles in both polymerization systems with and without emulsifier. The intra-and intermolecular association of polyacrylamide with its monomer is suggested to be the dominant process which induces the formation of particles responsible for the kinetics typical for the micellar or microemulsion polymerization. The experimental data show that the dependence of the maximal rate of polymerization (R p,max ) vs. conversion is the result of polymerization within the nanoscaled polymer aggregates and not by the gel effect. R p,max decreases with increasing emulsifier concentration and the decrease is much more pronounced with hydrophilic emulsifier. Polymerization is faster for the APS-initiated system than for the AIBN-initiated one. The radical polymerization of AAm polymerization with and without emulsifier was discussed in terms of the formation of polymer chain aggregation (nanoparticle) into polymer chains as a main reaction locus.

Minisci C−H Alkylation of Heteroarenes Enabled by Dual Photoredox/Bromide Catalysis in Micellar Solutions**

“…Unique properties of structured solutions of surfactants, combined with operationally simple preparation, render them advantageous media for chemical reactions such as biocatalysis, [41] polymerizations, [42] transition‐metal‐catalyzed cross‐coupling reactions, [43] and organocatalytic transformations [44] . Recent reports show that they may also play a vital role in photocatalysis [30, 45–48] .…”

Minisci C-H Alkylation of Heteroarenes Enabled by Dual Photoredox/bromide Catalysis in Micellar Solutions

“…Unique properties of structured solutions of surfactants, combined with operationally simple preparation, render them advantageous media for chemical reactions such as biocatalysis, 41 polymerizations, 42 transition-metal catalyzed cross-coupling reactions, 43 and organocatalytic transformations 44 . Recent reports show that they may also play a vital role in photocatalysis.…”

Synthesis of water-soluble ionic terpolymers by inverse microemulsion and solution polymerization methods

“…[1][2][3][4][5][6] The synthesis of these macromolecules can be achieved by different synthesis methods such as aqueous solution polymerization, 7-10 mass polymerization, and inverse microemulsion polymerization. 11,12 Nonetheless, each method features a series of advantages and disadvantages that have to be considered. One of the main characteristics of polymerization reactions is that they are highly exothermic, and a large amount of heat must be removed from the reaction medium.…”