Microemulsion polymerization of styrene in the presence of macroinimer |
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Authors: | Ufuk Yildiz Ignac Capek |
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Affiliation: | a Department of Chemistry, Kocaeli University, 41300 Kocaeli, Turkey b Max Planck Institute of Colloids and Interfaces, Am Mühlenberg, 14476 Golm, Germany c Polymer Institute, Slovak Academy of Sciences, 842 36 Bratislava, Slovakia |
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Abstract: | The kinetics of o/w electrostatically and sterically-stabilized microemulsion polymerization of styrene with and without macromonomeric azoinitiator (macroinimer; MIM) have been investigated. The microemulsion polymerization stabilized by the ionic emulsifier sodium dodecyl sulfate (SDS) or the non-ionic emulsifier Tween 20 (Tw 20) was initiated by ammonium peroxodisulfate (APS)/sodium thiosulfate (STS) redox system. The rate of polymerization vs. conversion curve shows the two non-stationary rate intervals. This behavior is a result of two opposing effects, the continuous particle nucleation and the decrease of monomer concentration at the reaction loci. The addition of MIM favors the additional particle nucleation. The sterically (Tw 20)-stabilized microemulsion polymerization is much faster than that of the electrostatically (SDS)-stabilized microemulsion polymerization. This was attributed to the higher Tw 20 concentration and increased solubilization of MIM and comonomer concentration in the polymer particles. The formation of initial large polymer particles is attributed to the intensive agglomeration polymer particles with monomer droplets. The continuous decrease in the average size is mainly attributed to the additional particle nucleation. |
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Keywords: | Macromonomeric azoinitiator Macroinimer Microemulsion polymerization |
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