Synthesis of poly(methyl methacrylate) nanoparticles initiated by azobisisobutyronitrile using a differential microemulsion polymerization technique

Abstract

Nanosized poly(methyl methacrylate) (PMMA) particles with a high molecular weight of 10 6 g mol À1 and a polydispersity index of about 1-2 were synthesized, for which 2,2 0 -azobisisobutyronitrile was used as the initiator and a differential microemulsion polymerization technique was employed. The kinetics of the polymerization, the glass transition temperature, tacticity, the particle size distribution, and the morphology of the nanosized PMMA synthesized were investigated. The dependence of the number of the polymer particles (N p ) and the number of the micelles (N m ) on the concentration of the surfactant was discussed. The molecular weight distribution was found to be nearly constant over the polymerization time, which was attributed to the significance of micellar polymerization. The resultant nanosized PMMA has a rich syndiotactic configuration (53-57% rr triads) with a glass transition temperature of about 125 C. A beneficial operation condition was discovered where the conversion reached a maximum at a high monomer-to-water ratio.

Modeling the Semicontinuous Heterophase Polymerization for Synthesizing Poly(n‐butyl methacrylate) Nanoparticles

“…However, it is not a simple task to compare the coefficients of entry to micelles with literature values because in some cases, the value is not reported explicitly and some works calculate a second order coefficient (i.e., k cm = ). It is interesting to note in Table that the rate constant of radical capture by micelles obtained by this methodology is non‐zero only for the lowest feed rate and that its value agrees in order of magnitude with previous works for the microemulsion polymerization of styrene; moreover, its value is much smaller than the rate of entry to particles ( k cp ).…”

“…A novel variation of the semicontinuous microemulsion polymerization has been reported in recent years, that has the advantages of emulsion and microemulsion polymerization processes, mainly because it allows the synthesis of nanoparticles with similar or smaller sizes than those obtained by microemulsion polymerization, and yields large polymer contents using small amounts of surfactant . Here, either monomer is fed continuously drop‐wise over a period of time ( differential microemulsion polymerization ) or at a controlling rate [ semicontinuous heterophase polymerization (SHP)] over a monomer‐free aqueous solution containing only surfactant and initiator to achieve monomer‐starved conditions; under these conditions no emulsified or microemulsified monomer droplets are present in the process. Furthermore, molar masses produced by this type of processes are smaller than those obtained by microemulsion polymerization, and they can be controlled by the monomer feeding rate …”

Ultra-High Molecular Weight Alpha-Amino Poly(Methyl Methacrylate) with HighTgthrough Emulsion Polymerization by Using Transition Metal Cation-Tertiary Amine Pairs as a Mono-Centered Initiator

“…There have been several reports on preparation of PMMA with high T g (≥120 °C) via conventional radical polymerization under mild conditions. High‐ T g PMMA steadily formed via the radical polymerization in mini‐, or micro‐emulsion using AIBN, peroxysulfate or redox pairs as an initiator, which generate polymers with a high MW (>10 6 g mol −1 ) and a syndiotactic‐rich (rr > 50%) stereoregularity. Additionally, the post‐treatment during emulsion polymerization, such as precipitating and washing in copious ethanol and water, facilitates the dissolution and removal of MMA oligomers .…”

Synthesis of polybutadiene-silica nanoparticles via differential microemulsion polymerization and their hydrogenated nanoparticles by diimide reduction

“…This implied that at higher monomer to water ratio, polymerization of BD is more pronounced than graft polymerization onto SiO 2 since the grafting has a lower active surface area at the reaction site [24]. Moreover, most of the further added monomer molecules could diffuse into the existing polymer particles, which were larger than the newly nucleated particles, and monomer diffusion into the polymer particles required more time resulting in a decrease in monomer conversion [25]. A high monomer conversion (83%) and grafting efficiency (83%) were obtained via DMP at a low monomer to water ratio of 0.2 at which a small particle size (22 nm) was achieved.…”