Reactive Surfactants in Heterophase Polymerization. 11. Particle Nucleation

Abstract

The nucleation process in the emulsion polymerizations of styrene, methyl methacrylate, and vinyl acetate stabilized by sodium dodecyl sulfopropyl maleate, a polymerizable surfactant (surfmer), was investigated. A nonpolymerizable surfactant, sodium dodecyl sulfate (SDS), was used as a reference. The results obtained suggested that the presence of the surfmer did not affect the nucleation mechanism (which seems to be micellar for styrene and homogeneous for MMA and VAc). The type of surfactant did not affect the dependence of the number of particles upon surfactant concentration for styrene, but the dependence for the surfmer was lower than that for SDS in the cases of MMA and VAc. This was interpreted in terms of formation of water-soluble oligomers that do not participate in the stabilization of the polymer particles.

Reactive surfactants in heterophase polymerization

“…Chain transfer to surfmer, leading to a decrease in the number of radicals in the particle, was found to be the predominant factor explaining the kinetic results. However, this model does not account for the following experimental results: i) relatively speaking, maleate surfmers reacted faster than styrene [63,129] even though reactivity ratios are strongly in favor of styrene; ii) the surfmer conversion increased as particle size decreased [62]; and iii) the surface yield is higher for water-soluble initiators than for oil-soluble initiators [28,110]. Preliminary simulations show that to account for these results a non-uniform profile of radicals should be included in the mathematical model [114].…”

“…However, at the end of the semi-continuous reaction most of the acrylic monomers have been depleted, and a relatively high amount of VAc is left which copolymerizes well with the maleate surfmer, which reacts to completion [64]. However, the mechanical stability is not very high [117] and it was suggested that the poor stability despite the reaction of the surfmer at the end of the monomer addition period was due to the formation of alternating copolymers with the VAc. Hence, it is concluded that, as a general rule, the higher the conversion of the surfmer during the semicontinuous process (due to a higher reactivity) the lower the stability of the latex and the higher the amount of coagulum.…”

“…Amalvy et al [129] studied the particle nucleation process in the batch emulsion polymerization of three monomers of widely different water solubility and reactivity ratios (styrene, methyl methacrylate and vinyl acetate) stabilized with an anionic surfmer (sodium dodecyl sulfopropyl maleate, M12). S is sparingly soluble in water and copolymerizes reasonably with maleates (r s = 8 -10, r maleate = 0 [130]), MMA is more water-soluble and is in theory too reactive to allow copolymerization with maleates (r MMA = 354 l 57, r diethyl maleate = 0 [131]), and VAc is even more water-soluble and reacts almost alternatingly (r VAc = 0.043, r diethyl maleate = 0.17 [130]).…”

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

“…Also, it has been found that the overall rate coefficient for radical entry into particles was independent of the particle size. 8,[11][12][13][14][15] Studies of the effect of a reactive surfactant on the entry and exit rate coefficients have not been performed. It would be of interest to relate the results obtained for the entry and exit rate coefficients in seeded emulsion * To whom correspondence should be addressed.…”

Polymerizable and Nonpolymerizable Isophthalic Acid Derivatives as Surfactants in Emulsion Polymerization

“…This can be achieved by using a polymerizable surfactant (surfmer), [12][13][14][15][16][17][18] which is a combination between a monomer and a surfactant. Recently, a number of articles have been published on the subject, showing the interest in reactive surfactants [19][20][21][22] as well as in reactive macroemulsifiers. 23,24 Derivatives of isophthalic acid have been used as model compounds in the study of macroscopic supramolecular aggregates in various phases.…”