The picosecond to nanosecond solvation dynamics in liquid poly(ethylene glycol)s (PEG) with the molecular weights of 150 - 600 and liquid crown ethers (CE), 12-crown-4 and 15-crown-5, have been characterized using a picosecond time-resolved fluorescence spectroscopy. The observed solvation dynamics for the PEGs and CEs shows a biexponential function. The faster solvation time constant of 130 ps is insensitive to the molecular weight and the molecular geometric structures. The slower solvation time constant (0.5 - 1.6 ns) depends on the molecular weight and the molecular geometric structure of the macromolecules.
The deuterium isotope effect of the end hydroxyl groups of PEG on the solvation dynamics has also been investigated to see the role of the end groups on the solvation dynamics. The slower solvation component becomes slower by deuterium isotopic substitutions of the PEG’s end groups. The result indicates that the slower solvation dynamics for the poly(ethylene oxide)s is influenced by the molecular structure including the presence of the hydroxyl groups.
In order to investigate the faster dynamics of polymer solutions the femtoseocnd optical Kerr effect spectroscopy set-up is now constructing. About 10 fs pulse from a lab-built titanium sapphire laser is obtained. I believe new facts regarding the dynamics of polymer solutions will appear by the femtoseocnd optical Kerr effect spectroscopy.