The effect was studied of various layered silicates (sodium montmorillonite and different organomodified montmorillonites) on kinetics of styrene (St) and butyl acrylate (BuA) in anionic (sodium dodecyl sulfate) microemulsion polymerization. The dependence of the polymerization rate on the conversion exhibits two rate intervals. The presence of layered silicates affects the conversion and polymerization rate of both St and BuA. The size of polymer particles increases with polarity of Cloisite and the increase is more pronounced in poly(butyl acrylate) particles. The kinetic, colloidal and molecular weight parameters are influence both by the monomer and layered silicate polarities. Different approaches (Ugelstadt, Nomura and Gilbert models) were used for evaluation of polymerization kinetics. The desorption constants (k des ) decrease in presence of the studied layered silicates (Cloisite Na, Cloisite 30B, Cloisite 20A). The decreasing values of the desorption constants in the presence of clays; demonstrate a clear effect, which implies the decreasing of the probability of the radical exit from particles in the presence of the layered silicates.KEY WORDS: Microemulsion Polymerization / Layered Silicates / Kinetics / Nanolatexes / Nanocomposites / The synthesis of nanoclay composites from dispersed systems exhibit an increased interest in the last years. The main reasons include the encapsulation of layered silicates, nanolayer stabilization, in situ polymerization of the monomers in intergalleries of the layered silicates and the possibility of obtaining hybrid particles and nanoparticles.1-5 Even through the numerous reports about emulsion, miniemulsion and suspension polymerization of different monomers in presence of layered silicate can be found in the literature, the kinetics data are rather rare. 1,6,7 Some other papers 8,9 deal with the bulk polymerization of selected monomers, for example methyl methacrylate in presence of montmorillonite (MMT). It was found that an optimal ratio of MMT/initiator (benzoyl peroxide) promotes an increase in the polymerization rate of methyl methacrylate. 8Presence of an organomodified montmorillonite also increases the polymerization rate of styrene in bulk polymerization. 9 In the case of emulsion polymerization of styrene the reaction rate is enhanced by the presence of sodium montmorillonite, however the study handles only one level of inorganic filler. 10In the miniemulsion polymerization of styrene in presence of laponite the silicate layers can be on the surface of the particle but also inside the emulsion-latex particle depending on the initiator nature. 7 In suspension polymerization of styrene in presence of different organophilic montmorillonites silicates are likely also inside the particle.11 For suspension polymerization of methyl methacrylate in presence of organophilic montmorillonite the clay layers are situated both inside and on the surface of the latex particles.12 In this case, the kinetics of the monomer polymerization is much influenced by the presenc...

The inverse emulsion polymerization of acrylamide (AAm) initiated by a water-soluble initiator (ammonium peroxodisulfate, APS) was investigated. The rate of inverse emulsion polymerization increased with both increasing initiator and emulsifier concentrations. The molecular weight of polyacrylamide decreased with increasing the initiator concentration and slightly rose with increasing the emulsifier concentration. With increasing APS concentration the curves are broader. This indicates widening of molecular weight distribution. The decrease in M w with increasing APS concentration results from the increased termination of growing radicals mainly by primary or oligomeric radicals. The number of radicals per particle was inversely proportional to the APS concentration. The increased deactivation of primary and monomeric radicals decreased their desorption rate and re-entry rates as well. The desorption rate of radicals was interpreted using three models: the Nomura model (N model , k des,N ), the Gilbert model (G model , k des,G ) and the Ugelstadt model (T model , k des,T ). The desorption rate constant (k des ) for the different models differs by up to two orders of magnitude. The value of k des increases in the following order: N model < G model < T model . The radical entry rate decreases with rising emulsifier concentration and increases with rising initiator concentration.  Koninklijke Brill NV, Leiden, 2008

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