The micellization behavior of cetyltrimethylammonium bromide (CTAB) is investigated in the absence and presence of poly(ethylene oxide) employing surface tension, light scattering, and viscosity and conductance measurement. It has been concluded that the critical micellization concentration (CMC) of CTAB in the presence of polymer increases with the increase in polymer concentration. The three ranges of interaction among the polymer and CTAB with respect to concentration of CTAB are identified at surface tension plot and noted to depend upon polymer concentration. The effect of temperature over these interactions and CMC of CTAB has been investigated. It is observed that the CMC, DH, and flow activation energy of the system increases with the increase in polymer concentration whereas CMC of CTAB decreases with the temperature. R H and R g /R H values determined by light scattering also indicate such type of behavior. The CMC values have also been obtained by viscosity and conductivity measurement. The results and conclusions drawn through all the techniques were consistent. New methodology has also been introduced to interpret the data obtained by surface tension, viscosity, and conductance measurement, and get information about the point of interaction and saturation of polymer with surfactant, which was noted to be very useful and informative.

INTRODUCTIONA high percentage of pharmaceutically active compounds are insoluble in water having low and variable bioavailability 1,2 . Therefore, several techniques are in practice to increase the solubility of such drugs including the utility of the surfactants/ amphiphiles [3][4][5][6][7] . Surfactant are the substances that preferentially adsorb at an interface and lower the interfacial tension between two liquids or phases 8 . A large number of surfactants are available in the market, which have wide spread applications in different industries including dyestuffs, cosmetics, detergents, paints, plastic fibers, pesticides, pharmaceuticals and lubricants etc. 9 . The surface activity of surfactants is due to their amphiphilic structure having both a polar or hydrophilic head and a non-polar or a hydrophobic tail 10 . Their vital role in both fundamental and applied sciences is due to their most spectacular property to assemble into higher order structures spontaneously. This process is commonly known as self-assembly. It usually involves molecules that contain two distinct components, differing in their affinity for solutes. Molecules containing both hydrophobic and hydrophilic types of components with distinctive chemical and physical properties are said to be amphiphiles.An amphiphilic molecule can arrange itself at the surface of the water such that the polar part interacts with the water and the non-polar part is held above the surface (either in the air or in a non-polar liquid). The presence of these molecules