Self assemble behavior of poly (oxybutylene-oxyethylene) (bmenbm) triblock copolymer in solution

Amphiphilic block copolymer of two triblock copolymer B/sub 17/E/sub 122/B/sub 17/ and B/sub 24/E/sub 450/B/sub 24/, B denoting OCH/sub 2/CH(C/sub 2/H/sub 5/), E denoting OCH/sub 2/CH/sub 2/, 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 (Gmic) value was found to decrease in the range (-18 to -23KJmol-1) with the increase of temperature. Standard entropy factor of micellization (TSmic) also increased in the range (51.04 to 56.33 KJmol-1) with the rise in temperature, while enthalpy (Hmic) 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. (author)