The BZ-AOT System

All the initial reagents of the BZ reaction are hydrophilic and migrate into the water core of the droplets. Diffusion within single droplets plays no role in the pattern-forming mechanism of the BZ-AOT system, because of the small size of the droplets. Highly polar species are essentially confined to the water core of the droplets. Their diffusion coefficient is determined by the diffusion coefficient of the water droplets D, if the volume fraction of the droplets is l ss than the percolation threshold 0p (around 0.5) of the microemulsion. The value of depends on the... 

Vanag and Epstein have formulated a four-variable model to understand pattern formation in the BZ-AOT system [449,453]. Their model builds on the Oregonator, see Sect. 1.4.8. It assumes that the chemistry within the water core of the droplets is well described by the two-variable Oregonator rate equations (1.131). It further assumes that the species in the oil phase are inert, since they lack reaction partners, the key reactants all being confined to the aqueous core of the droplets. Consequently, only transfer reactions occur for the activator B1O2 and inhibitor Br2 in the oil phase. The rate terms for the two transfer reactions are added to the rate terms of the two-variable Oregonator model. The reaction-diffusion equations of the four-variable model of the BZ-AOT system are given in nondimensionalized form by... 

In another important study in the BZ-AOT system [69], the species Br2 can be identified. Bromine diffuses rapidly in the oil phase and inhibits autocatalysis through its facile conversion into Br, which is the acmal inhibitor in the BZ reaction. Many different Turing patterns have been found in the BZ-AOT system several are shown in Fig. 1.8. All the patterns in Fig. 1.8 are stationary, even those in Fig. 1.8f that resemble the concentric ring wave patterns. In Fig. 1.8, we can see spots (b), stripes (a), and labyrinthine (d) patterns. Mixtures of stripes and spots are also possible as shown in Fig. 1.8e. 

Balasubramanian et al. in 1988 [75] reported first illustration of the inclusion of the BZ reaction into an AOT reverse micelle system. The coupling of an oscillating chemical reaction which shows spatial and temporal phenomenon relevant to biological systems was the main motivation for this study. In manganese-catalyzed reaction system oscillatory behavior was monitored for this particular case. Vanag et al. [76] has been studied the BZ-AOT reaction in a great detail emphasized in particular on the formation of non-equilibrium chemical patterns. 

Fig. 1.10 Chemical waves and space-time structural patterns studied in the BZ-AOT reaction system (Adopted from Ref. [12])...

An intriguing example is BZ-AOT experiment [12], in which the constituents of the BZ system are dispersed in a reverse microemulsion containing an oil (octane) and the surfactant sodium bis(2-ethylhexyl) sulfo-succinate. Manipulation of... 

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