Effect of a Reactive Surfactant and Its Polymeric Counterpart on the Kinetics of Seeded Emulsion Polymerization of Styrene

Abstract

Seeded emulsion polymerizations of styrene using the reactive surfactant sodium dodecyl ally sulfosuccinate (TREM LF-40) and its polymeric counterpart, poly(TREM), were carried out, and their reaction kinetics were compared to those obtained using the conventional surfactant sodium lauryl sulfate (SLS). The reaction rate decreased using TREM LF-40 and poly(TREM), compared to SLS. For TREM LF-40, this behavior was attributed to the participation of TREM LF-40 as an allylic monomer in copolymerization and/or chain transfer reactions at the surface of the particles. For poly(TREM), the decrease was considered to be caused by the formation of a "hairy" adsorbed layer of the polymeric surfactant on the particles, which acts as a barrier decreasing the diffusion of the radicals into the particles. It was also found that the rate decreased with increasing TREM LF-40 concentration as expected, this being attributed to increased reaction at the surface of the particles with increasing surface coverage by the surfactant. However, over the range of poly(TREM) concentrations studied, no such trend was apparent, perhaps indicating a saturation of the effect of poly(TREM) on the entry of the radicals. These results were supported by the molecular weights of the resulting polymers. Compared to the latexes polymerized with SLS as the stabilizer, the polystyrene molecular weights of the latexes stabilized with TREM LF-40 were smaller. For poly(TREM), the resulting polystyrene molecular weights were larger than obtained for the SLS stabilized seed, considered to be consequence of a decrease in the entry rate of the radicals into the polymer particles.

Kinetics of emulsion polymerization of styrene using the reactive surfactant HITENOL BC20

“…Differences from Smith‐Ewart dependencies ( R p ∝ [E] 0.6 and R p ∝ [I] 0.4 ), however, have been reported even for conventional surfactants 13–15. Nonetheless, it is considered likely that the reactive surfactant plays some role in reducing these dependencies via copolymerization or chain transfer (to the EO groups) 12, 16. Evidence for the latter was seen by comparing polymerizations using BC20 and its hydrogenated counterpart (i.e., no double bonds).…”

Effect of Pickering stabilization on radical entry in emulsion polymerization

“…However, for some specific cases, the stabilizing layer was reported to affect radical entry as for instance in the case of the nonionic NP30 polyoxyethylene nonylphenol surfactant (with 30 EO units) . Similar conclusions were reported for the reactive surfactant sodium dodecyl allyl sulfosuccinate . Some polymeric surfactants were also reported to impact radical entry (e.g., copolymers of acrylic acid and styrene, copolymers of styrene and styrene sulfonate, and to a lower extent poly[acrylic acid]), especially when the charge of the entering radicals was different from that of the polyelectrolyte surfactant .…”

Role of Surfactants in Emulsion Polymerization Polymers by design

“…This unusual proportionality between R p and N p could result from a combination of various factors: (1) copolymerization between TREM LF-40 and styrene (12-14% TREM LF-40 partitioned into the styrene phase), (2) chain-transfer to TREM during the polymerization (C s = 111 x 10 -4 determined by solution polymerization at ≤ 10% conversion) [15], and (3) reduced radical entry and exit because of the existence of a "hairy" layer of the polymeric surfactant, since TREM LF-40 can homopolymerize. Kinetics of seeded dispersion polymerization and the resulting polymer molecular weights [16] brought supporting evidence for the existence of the chemical reactions, primarily chain transfer to TREM LF-40 at the surface of the particles, that lowered the dependency of the rate of polymerization on emulsifier concentration.…”