Narrow size‐distribution poly(methyl methacrylate) nanoparticles made by semicontinuous heterophase polymerization

Abstract

The effect of surfactant (sodium dodecyl sulfate) concentration on particle size, molar masses, glass transition, and tacticity of poly(methyl methacrylate) (PMMA) nanoparticles synthesized by semicontinuous heterophase polymerization under monomer-starved condition at constant monomer feeding rate is reported. Starved conditions are confirmed by the low amount of residual monomer throughout the reaction and by the fact that the instantaneous polymerization rate is similar to the feeding rate of monomer. Under these conditions, polymer particles in the nanometer range (20-30 nm) were obtained with narrow size distribution (1.07 < D w /D n < 1.18), depending of surfactant concentration. Final particle size diminishes as the surfactant concentration is increased. Glass transition temperatures and syndiotactic content (54%-59%) of the produced polymers are substantially higher than those reported for commercial and bulkmade PMMA. Molar masses are much lower than those expected from termination by chain transfer to monomer, which is the typical termination mechanism in 0-1 emulsion and microemulsion polymerization of this monomer.

Ultrasound-assisted polymerization of methyl methacrylate using the reactive surfactant Hitenol BC10 in a semicontinuous heterophase process

“…Then, ultrasound has an important effect on kinetics polymerization by facilitating monomer diffusion between phases and decreasing particles sizes, as will be [22] studied the effect of surfactant concentration in the heterophase polymerization of MMA using only SDS as surfactant, and found that instantaneous conversion increases with SDS concentration, which supports the assumption of chain transfer to HBC10 in our experiments.…”

“…On the other hand, Aguilar et al [22] found a D pz value of 29 nm (R a = 0.15 g/min and polymer content of 22 %) using only SDS as the surfactant in a concentration of 3 %; P/S was 10. The corresponding D pz value obtained in the present work for Run 6 was 39 nm (R a = 0.2 g/min and polymer content of 21 %) with P/S = 13 and surfactant concentrations of 1.6 %.…”

“…This imposes some delay time, which decreased with increasing R a [22]. Figure 5 shows the kinetics of polymerization at different R a as a function of relative time.…”

Semicontinuous heterophase polymerization of methyl methacrylate in the presence of reactive surfactant HITENOL BC10

“…This is contrary to what is normally expected for a conventional surfactant. For example, Aguilar et al [20] used SDS as surfactant to polymerize MMA by semicontinuous heterophase polymerization under monomer-starved condition at constant monomer addition rate. They found molar masses much lower than those expected from termination by chain transfer to monomer, which is the typical termination mechanism in 0-1 emulsion and micro-emulsion polymerization of this monomer.…”

Poly(methyl methacrylate) nanolatexes with high solid contents prepared by semi-continuous emulsion polymerization in the presence of oil-soluble initiators

“…When the weight ratio of AIBN to MMA is kept constant, the molecular weight of PMMA nanolatex particles increases substantially with the increasing MMA concentration (Group D). At a MMA concentration of 315 mg mL À1 , the molecular weight of PMMA nanolatex particles increases to 39.6 Â 10 5 g mol À1 , which is much larger than those of PMMA nanolatex particles fabricated via the KPS-initiated semi-continuous heterophase polymerization [10,27]. Finally, most PMMA nanoparticles display a fairly narrow molecular weight polydisperisity.…”