Semicontinuous heterophase polymerization under monomer starved conditions to prepare nanoparticles with narrow size distribution

Abstract

The semicontinuous polymerization of methyl methacrylate (MMA) in heterogeneous medium under monomer‐starved conditions is reported here. The effect of monomer addition rate on kinetics, particle size, particle number, and PMMA average molar masses are reported. This process permits the synthesis of high‐solid content latexes containing nano‐sized particles (<40 nm) with narrow particle size distributions [(Dw/Dn) < 1.1]. Moreover, the molar masses (Mn ≈ 0.3–1.2 × 106 g/mol) are much lower than those expected by chain transfer to monomer, which is the typical termination mechanism in 0–1 emulsion and microemulsion reactions. Both particle size and average molar masses decrease as the rate of monomer addition is diminished. Possible explanations for this process are provided. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1463–1473, 2007

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

“…Similar results were observed when the mixture of SDS/AOT (3:1 wt/wt) was used as surfactants [4]. However, Lai et al [8] using the reactive surfactant polyoxyethylene alkylphenyl ether ammonium sulfate; 20 Units of ethylene oxide (HBC20) in the batch emulsion polymerization of styrene, observed that the molecular weight increased with increasing surfactant concentration.…”

“…To start polymerization, monomer is added continuously at a constant rate (Ra). Ledezma et al [4] reported the semicontinuous heterophase polymerization of methyl methacrylate (MMA) using a mixture of SDS and Aerosol-OT (AOT) as surfactants and KPS as initiator varying the Ra between 0.068 and 0.9 g/min, finding that latexes with high polymer content, D p \ 40 nm and narrow PSD can be obtained by this process. Semicontinuous heterophase polymerization can be used to obtain polymeric nanoparticles with tuned morphology.…”

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

“…Comparing our system with literature reports in similar conditions to Run 6, we found the work of Ledezma et al [26] who obtained a D pz value of 26 nm (R a = 0.22 g/ min and polymer content of 24 %) using conventional surfactants (SDS/AOT 3:1) concentration of 3.7 %, achieving polymer to surfactant weight ratios (P/S) of 6.6. 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.…”

“…Ledezma et al [26] studied the semicontinuous polymerization of MMA under monomer-starved conditions at different R a using a mixture of SDS/AOT (3/1 wt/wt) as surfactants and without employing ultrasound. From their results of instantaneous conversions, it was possible to calculate R pss as a function of R a (shown in Fig.…”

Exploring the limits of particle size for nanolatexes produced via monomer-starved semicontinuous emulsion polymerization

“…Semicontinuous monomer-starved emulsion polymerization is an appealing method for producing nanolatexes with relatively low amount of surfactant [9][10][11][12][13][14]. Several investigators used a wide range of formulations or process variables in order to reduce the particle size.…”