Effects of Different Stabilizers on Miniemulsion Methyl Methacrylate Polymerizations

Abstract

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.

Stabilization of Aqueous MMA Emulsions Using Mixtures of Surfactants and Implications on MMA Miniemulsion Polymerizations

“…[ 27,30,31 ] For all these reasons, the good initial miniemulsion stabilization performance may not reflect the good stabilization of the latex, as shown in previous studies conducted with surfactants of distinct characteristics. [ 10 ]…”

“…The use of these two nonionic surfactants provided the best stabilization and reaction performances, as described in a previous work that investigated the use of distinct surfactants in MMA miniemulsion polymerizations. [ 10 ] Miniemulsion polymerization reactions were carried out in presence of the ionic surfactant SDS and the initiator potassium persulfate (KPS), both purchased from Vetec Química Fina (Rio de Janeiro, Brazil) with a minimum purity of 90 wt.% (containing 10 wt.% of water). The buffering agent sodium bicarbonate was acquired from Proquimios (Rio de Janeiro, Brazil) with a minimum purity of 99 wt.%.…”

“…Emulsion stability was evaluated with help of two performance indexes: the clarification index and the turbidity analysis index. [ 10,17 ] For evaluation of the clarification index, 10 mL of a just prepared emulsion was poured into a sealed graduated cylinder and the heights of the initial emulsion and of the clarified phases after 24 h of rest were recorded at room temperature. The final clarification index (%) was calculated as Equation (2) [ 23 ] : $$$$\begin{equation}Clarification{\rm{\;}}index{\rm{\;\;}}\left( {\rm{\% }} \right){\rm{\;}} = {\rm{\;}}\frac{{heigh{t_{clarified{\rm{\;}}layer}}}}{{heigh{t_{initial{\rm{\;}}total{\rm{\;}}emulsion{\rm{\;}}height}}}}{\rm{\;\;}} \times {\rm{\;}}100\end{equation}$$$$…”

“…[ 6,9 ] Despite that, experimental investigations focused on the use of surfactant mixtures and optimization of surfactant compositions for improvement of miniemulsion polymerization performance are relatively scarce in the literature and virtually absent in the methyl methacrylate (MMA) literature, as recently revised by Alves et al. [ 10 ]…”

“…[ 9 ] Particularly, Tween80 and Span80 have shown very good performances for the stabilization of emulsions of MMA in water and in miniemulsion MMA polymerizations. [ 10 ] However, blending of nonionic and ionic surfactants could also constitute a suitable strategy to improve the performance and stabilization of oil‐in‐water emulsions, [ 14 ] although this has rarely been considered and investigated for the formulation of miniemulsion polymerization recipes and has not been investigated yet in the field of MMA miniemulsion polymerizations.…”