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Micellar systems photochemical effects

An important aspect of photochemical effects in micelles is the formation and stabilization of charge transfer effects with a view to application in solar energy conversion. An example of this is a study of electron transfer in micellar-metal ion systems, where k and electron transfer yields from S. states of pyrene and N-ethylcarbazole, and the T state of N-methylphenothiazine by a... [Pg.22]

Based on the knowledge of micellar catalytic effects, an exclusive photochemical reaction mechanism in micellar solution possibly may be expected or designed to fulfill each particular environmental problem. Thomas J.K.. (1980) proposed four possible photochemical reaction mechanisms that might exist in micellar system (see Figure 2). [Pg.35]

Photoinitiated Addition Polymerization.—The role of carbonyl compounds in initiating photopolymerization continues to be an area of prolific research. Laser flash photolysis has provided a valuable insight into both the photophysical and photochemical processes involved in carbonyl-initiated photopolymerizations. For example, Fouassier and co-workers have found that carbonyl-initiated vinyl polymerization proceeds faster in a micellar system and an example of this interesting effect is shown in Table 1. Laser flash photolysis has shown that... [Pg.502]

Photochemistry in micellar systems is a type of micellar catalysis in the sense that the photochemical process takes place in the micellar domain. The outstanding recent progress in micellar photochemistry is well laid out in a number of review articles and papers on photochemical and photophysical processes in micellar assemblies. " As described in previous chapters, hydrophobic organic solutes solubilize well in the micellar core, whereas the micellar surface controls the concentration of hydrophilic solutes. The electrostatic potential of up to a few hundred millivolts at the surface of ionic micelles is especially effective in attracting or repelling ionic species. Thus, micelles are microscopically heterogeneous and well suited as surfaces for reactions of appropriate reactants. [Pg.211]

Haidar, M Misra, A., Banerjee, A. K. and Chowdhury, M. (1999) Magnetic field effect on the micellar (C)-pyrene- radical-pair system. J. Photochem. Photobiol. A, 127, 7-12. [Pg.278]

Photochemical processes in heterogeneous systems, and across micelle boundaries in particular, clearly has great potential. The photolysis of amphipathic alkylcobaloximes in mixed micelles shows a co-operative effect owing to structure.The photoreduction of anthraquinone in aqueous micellar solution has been compared with that in non-aqueous solution.The dimerization of 3-(n-butyl)cyclopentenone is solvent-dependent and the ratio of isomeric products depends on surfactant concentration. It is suggested that this can be used as a means of critical micellar concentration determination. [Pg.85]

The photochemical perturbation of the system Ni and PADA produces two relaxation effects in both aqueous and micellar media characterised by widely differing relaxation times. The faster process is independent of the concentration of both Ni and PADA but is dependent on temperature. In bulk water at 298.2 K the fast (F) relaxation time Tp has a value of 35( 4) ys, which gives a first order rate constant of 2.9( 0.3) x 10 s . This fast process is identified with ring closure (step 3 of figure 2) following photochemical generation of the monodentate complex. The activation energy (E )p for this process is found to be 40 4 k J mol . ... [Pg.324]


See other pages where Micellar systems photochemical effects is mentioned: [Pg.90]    [Pg.261]    [Pg.60]    [Pg.306]    [Pg.26]    [Pg.24]    [Pg.364]    [Pg.326]    [Pg.175]    [Pg.336]    [Pg.60]    [Pg.508]    [Pg.378]    [Pg.182]   
See also in sourсe #XX -- [ Pg.292 ]




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