Solute dynamics has been explored in reverse micelles formed with the triblock copolymer (EO)13– (PO)30–(EO)13
(L64), where EO and PO represent ethylene oxide and propylene oxide
units, respectively, with small amounts of water in p-xylene. To this
effect, nonradiative rate constants (knr) and reorientation times (t r) of two carbocyanine derivatives, 3,3'-diethyloxadicarbocyanine iodide
(DODCI)
and merocyanine 540 (MC 540) have been measured at different mole
ratios of water to copolymer (W) and also at three copolymer
concentrations. By examining the nonradiative rate constants and the
reorientation times of the two solutes, the microenvironment offered by
L64/water/pxylene reverse micellar system has been investigated. It has
been observed that there is no variation in the nonradiative rate
constants as well as in the reorientation times of both DODCI and MC 540
with an increase in W and [L64]. Since knr represents
activated twist motion about the double bonds for these solutes, it is
sensitive to the local friction and likewise, t r also provides information about the microenvironment. Thus, the results of this study indicate that DODCI and
MC
540 are located in the cores of the L64 reverse micelles that are made
up of hydrated ethylene oxide blocks and the hydration levels are not
altered despite an increase in the water content and copolymer
concentration. In other words, there is no variation in the
microenvironment offered by L64/water/p-xylene reverse micellar system
upon increasing W and [L64].