Role of sodium dodecylbenzenesulfonate in 2,2,6,6‐tetramethy‐1‐piperidinyloxy‐mediated styrene miniemulsion polymerization

Abstract

In studying 2,2,6,6-tetramethy-1-piperidinyloxy (TEMPO)-mediated styrene miniemulsions, we have observed that the surfactant sodium dodecylbenzenesulfonate (SDBS) not only provides colloidal stability but also influences the rate of polymerization. Increasing the SDBS concentration results in higher polymerization rates, although the molecular weight distribution and particle size distribution are not significantly impacted. We have also examined another common sulfonate surfactant, DOWFAX 8390. In contrast to SDBS, DOWFAX 8390 does not affect the polymerization rate. Furthermore, DOWFAXstabilized polymerizations are slower than SDBS-stabilized polymerizations. TEMPOmediated bulk styrene polymerizations are also accelerated significantly in the presence of SDBS. Although the mechanism for the rate acceleration is unknown, the experimental evidence suggests that SDBS is participating in the generation of radicals capable of propagating, thereby reducing the TEMPO concentration within the particles. Figure 4. (a) Conversion versus time, (b) M n versus conversion, and (c) polydispersity versus conversion for bulk styrene polymerizations with and without added SDBS: (^) styrene/SDBS ¼ 0 and (n) styrene/SDBS ¼ 1:0.0041. 5984 LIN, HSU, AND CUNNINGHAM

Gelation and Hollow Particle Formation in Nitroxide‐Mediated Radical Copolymerization of Styrene and Divinylbenzene in Miniemulsion

“…Both R p and the control/livingness of TEMPO-mediated polymerization of S in miniemulsion can be different from the corresponding bulk/solution polymerization as a result of compartmentalization, [35][36][37][38] the interface effect [39][40][41][42] (related to surface activity of the nitroxide, not polymer related interface effects as discussed below), and enhanced thermal (spontaneous) initiation. [42][43][44] The magnitude of these effects increase with decreasing particle size. In the present study, the particles were relatively large (d n (d w ) % 200(220) nm), and thus the solution and miniemulsion systems behaved similarly with regards to R p .…”

Recent advances in controlled/living radical polymerization in emulsion and dispersion

“…For TEMPO-mediated SFRP of St in miniemulsion, the rate of polymerization was greatly enhanced upon addition of ascorbic acid 174 and sodium dodecylbenzenesulfonate (SDDS). 175 This is due to the fast consumption of excess nitroxides during polymerization. There are two problems of concern for conducting TEMPO-mediated SFRP in miniemulsion at temperature of [120][121][122][123][124][125][126][127][128][129][130][131][132][133][134][135] C. One problem is the need of high pressure at around 300 kPa, which impedes an industrial application of TEMPO-mediated miniemulsion SFRP.…”

Controlled/Living Radical Polymerization in Aqueous Miniemulsion

“…nitroxide-terminated oligomers). In the latter case, the macroalkoxyamine is generally a short PS-TEMPO, either synthesized and isolated prior to its use in miniemulsion [70,76,77,79,81,82,95], or synthesized after a first step in bulk stopped at low monomer conversion followed by emulsification of the medium without further purification [74,80].…”