Quaternary microemulsions

Adhikari, S., Kapoor, S., Chattopadhyay, S., and Mukheijee, T. 2000. Pulse radiolytic oxidation of P-carotene with halogenated alkylperoxyl radicals in a quaternary microemulsion Formation of retinal. Biophys. Chem. 88 111-117. 

Ostergaard, T., Gomes, A., Quackenbush, K. and Johnson, B. (2004) Silicone quaternary microemulsion A multifunctional product for hair care. Cosmet. Toiletries, 119, 45. 

In most cases, it appears possible to interpret the critical behavior of microemulsion mixtures as a liquid/gas-like critical point [113-116]. Several light- and neutron-scattering studies on oil-rich ternary and quaternary microemulsions have clearly demonstrated that the structure of these media can be described as a solution of interacting water-in-oil droplets. As first shown by Calje et al. [117], the droplets may behave essentially as hard spheres. However, in many systems an attractive contribution to the interactions exists. It has been established that the strength of attractions between W/0 micelles is strongly dependent on the micellar size and on the chain lengths of both the alcohol and oil molecules. In particular, attractions have been found to increase when the micellar radius increases or the alcohol chain length decreases and the molecular volume of the oil increases [114, 115, 118-120]. 

Polymerisation of vinyl toluene in quaternary microemulsions containing cetyltrimethylammonium bromide as the cationic surfactant was studied using laser Raman spectroscopy and dilatometry. The influences of water soluble (potassium peroxodisulphate, ammonium peroxodisulphate) and oil-soluble (azobisisobutyronitrile, benzoyl peroxide) initiators, monomer, surfactant, cosurfactants (n-alcohol and bifunctional alcohols) and temperature on the rates of polymerisation, energy of activation, particle diameter, number of polymer particles, molecular weight of polyvinyl toluene and number of polymer chains per latex particle were investigated. The dependencies of the kinetic and latex size parameters on the initiators and co-surfactants are discussed in terms of the efficiency of the initiators in initiating the polymerisation and on the interfacial partitioning behaviour of various co-surfactants. 19 refs. 

The reduced penetration of the oil into the alkyl chains of the surfactant (and the consurfactant) in the palisade layers of ternary (or quaternary) microemulsions tends to cause the interface to become less curved, thereby favoring the growth of the natural (or spontaneous) radius of curvature, R°, and the formation of larger W/O microemulsion droplets [89] as well as increasing the accessibility of the binding sites on the surfactant molecules. 

Pure simple alcohols, alcohol/water binary systems, and ternary or even quaternary microemulsion systems containing alcohols are all very complex in terms of molecular organization. As these systems have been extensively studied using numerous experimental and theoretical methods, it seems that the majority of questions concerning their structural, interactional, and dynamic features have nowadays been resolved. However, we can be certain that with the evolution of new scientific techniques these systems will still provoke many more detailed investigations and probably open a lot of interesting scientific questions. 

Curri, M.L., Agostiano, A., Manna, L., Della Monica, M., Catalano, M., Chia-varone, L., Spagnolo, V., and Lugara, M. 2000. Synthesis and characterization of CdS nanoclusters in a quaternary microemulsion The role of the cosurfactant. Journal of Physical Chemistry B, 104, 8391-8397. 

S. Adhikari, R. Joshi, and C. Gopinathan, 1997. Hydrated electrons in a quaternary microemulsion system A pulse radiolysis study. J. Colloid Interface Sci. 191, 268-271. 

Kapoor, S., Adhikari, S., Gopinathan, C. and Mittal, J.P. (1999) Radiolydc production of metallic nanoclusters in a quaternary microemulsion system. Materials Research Bulletin, 34,1333-43. 

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