Surfactants self-organisation

Self-organisation of surfactant molecules in a water-surfactant system... 

Kinetic studies have been important in many areas of chemistry, but, to date, classic kinetic approaches have not played a major role in the area of colloidal science related to self-organisation of surfactants. Although micellar kinetics were investigated in some detail in the 1970s, related work involving other self-assembly systems, e.g., vesicles, lyotropic liquid-crystalline phases, have been limited. 

Self-organisation in surfactant solutions the Euclidean desert... 

Surfactants by definition self-organise in water giving rise to micelles of varying size and shape. The core of micelles is non-polar and can solubilise reactants that are insoluble in water. Thus, a simple surfactant-water system at a surfactant concentration well above the critical micelle concentration can be used to overcome the problem of reactant incompatibility the polar reagent will be situated in the bulk aqueous domain, the non-polar reagent will be present in the micelles, and the reaction will occur at the micelle boundary. Organic reactions in micellar systems have been reported more than 40 years ago [1,2]. 

If promising experimental results with respect to reaction rate, selectivity and yield motivate the development of an industrial process based on a self-organised surfactant system... 

Figure 2.6 Scheme of the mechanism for the formation of mesoporous silica. Silica polymers formed initially from silica monomers, and associated with surfactant monomers, which form composite self-organised primary particles which can either continue to grow via monomer addition (path 1) or themselves aggregate in a directional fashion (path 2) to form the final mesophase composite. Nondirectional aggregation would cause formation of disordered pore structures. Reprinted with permission from Nooney, R.I. Thirunavukkarasu, D. Chen, Y. Josephs, R. Ostafin, A.E., Synthesis of Nanoscale Mesoporous Silica Spheres with Controlled Particle Size, Chem. Mater., 14, 4721—4728. Copyright (2002) American Chemical Society... 

This result confirms the role of surfactant as an additional dopant to PANI. In presence of 2% SWNT, the conductivity of the nanocomposite dispersions containing NaDBS is much higher (11.08 S/cm) compared to its SDS counterpart 8.01 S/cm. It is known from the literature that both NaDBS and SDS show strong interactions with SWNT and self organisation on SWNT surface [10, 24]. However, from FT-IR and UV-spectroscopy, it can be suggested that combination of SWNT-SDS stimulate more restrictions on chain conformations of PANI as compared to NaDBS counterpart. As a result, higher conductivity is observed in nanocomposites prepared using NaDBS. 

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