The present work evaluated the effects of different ionic and nonionic stabilizers and respective concentrations on methyl methacrylate (MMA) miniemulsion polymerizations. The stabilities of the prepared miniemulsions are characterized through sedimentation and phase separation analyses and afterwards polymerizations are performed at the most stable conditions for each analyzed stabilizer. Monomer conversion profiles and final product properties are determined for comparative purposes. Obtained results indicated that the performances of the stabilizers during the polymerizations are not necessarily related to the stabilizing performances observed during preparation of the miniemulsions and that polymer latexes produced with the nonionic surfactant Tween80 presented the most suitable properties for applications in the biomedical field, as this stabilizer presented good stabilizing performances both during miniemulsion preparation and miniemulsion polymerization.

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Polyisobutylenes (PIB) constitute a versatile family of polymer materials that have been used mainly as fuel and lubricant additives. Particularly, the current commercial demand for highly reactive polyisobutylene (HR-PIB) products motivates the development of new processes and procedures to produce PIBs with high polymer yields, narrow molar mass distributions and high vinyl contents. For this reason, a bibliometric survey is presented here to map and discuss important technical aspects and technological trends in the field of solution cationic polymerization of isobutylenes. It is shown that investigations in this field are concentrated mainly on developed countries and that industrial initiatives indicate high commercial interest and significant investments in the field. It is also shown that use of catalyst systems based on AlCl3 and ether cocatalysts can be very beneficial for PIB and HR-PIB manufacture. Finally, it is shown that investigations search for cheaper and environmentally friendly catalysts and solvents that can be employed at moderate temperatures, particularly for the production of HR-PIB.

Miniemulsion polymerization is a robust and simple method for manufacture of polymer nanoparticles. However, it is strongly dependent on the precursor monomer-in-water emulsion stability. Thus, the present study investigates the influence of concentration and combination of nonionic surfactants (resulting in different hydrophile-lipophile balances, HLB) on the stabilization of emulsions of methyl methacrylate in water. Backscattering profiles obtained with Turbiscan show that a combination of Tween80 and Span80 can grant the desired initial system stabilization, although the optimum HLB values depend on the amount of surfactant mixture. Miniemulsion polymerizations are then successfully performed with nonionic surfactant mixtures, providing high monomer conversion in less than 1 h and poly(methyl methacrylate) nanoparticles with average diameters ranging from 300 to 500 nm. Finally, it is observed that the addition of small amounts of an anionic surfactant to the surfactant mixture (10 wt.%) can be very beneficial for the process, allowing the control of reaction rates, the production of smaller nanoparticles with average diameters from 100 to 300 nm, and the enhanced stabilization of the final solid dispersion, while simultaneously keeping the concentration of ionic surfactants small.

Polymer hydrogel nanoparticles are produced through inverse miniemulsion polymerizations, using acrylic acid as monomer and soybean oil as the continuous phase. A crosslinking agent is used to promote the reticulation of the polymer chains and production of hydrophilic nanogels. The synthesis of the polymer nanoparticles is studied with aid of a full factorial design using monomer content, crosslinker content, and reaction temperature as independent variables and monomer conversion and thermal stability of the obtained material as the main responses. The potential to encapsulate hydrophilic actives into the hydrogel matrix is evaluated by using a commercial blue dye as a model. It is observed that incorporation of the blue dye is efficient and that the rates of dye release are very low at different pH values, suggesting the existence of strong physicochemical interactions with the polymer matrix, which can be advantageous in bioimaging and paint applications. Particularly, the proposed inverse miniemulsion procedure enabled the production of stable nanogels.