Amphiphilic block copolymer of two triblock copolymer B17E122B17 and B24E450B24, B denoting OCH2CH(C2H5), E denoting OCH2CH2, and the subscripts denoting number-average chain lengths were investigated in solution and characterized through surface tension, viscosity, and dynamic light scattering. Critical micelle concentration, (CMC) determined from the surface tension data was found to decrease with the increase of temperature as well as with the increase in hydrophobic block length for both the copolymers investigated. Standard free energy of micellization (ΔGmic) value was found to decrease in the range (-18 to -23KJmol-1) with the increase of temperature. Standard entropy factor of micellization (TΔSmic) also increased in the range (51.04 to 56.33 KJmol-1) with the rise in temperature, while enthalpy (ΔHmic) is temperature independent. Viscosity and Dynamic light scattering were used to determine intermicellar interactions and to characterize the micelles in dilute solutions respectively. The data obtained demonstrated the formation of compact micelles at low temperatures and of elongated at higher temperatures.

Muhammad Siddiq, Imad-Ud-Din, Mohsan Nawaz, Wajid Rehman, Iram Bibi, Abbas Khan and Bakhtiar Muhammad