Simultaneous static and dynamic light experiments have been made on various cyclodextrins and cyclodextrin derivatives, as well as the inclusion complexes formed between different polyethylene oxide/polypropylene oxide triblock copolymers (PEO-PPO-PEO) (pluronics) and dimethyl--cyclodextrin (DIMEB). The inclusion complexes formed between DIMEB and pluronics are highly soluble, in contrast to the insoluble complexes formed between -cyclodextrin and the same substances. The static light-scattering (LS) data show that approximately 11 DIMEB molecules thread onto the copolymer chains and are located on the PPO block. With the inverse structure (PPO-PEO-PPO), about seven DIMEB molecules are present in the complex. NMR measurements are used to substantiate complex formation by means of characteristic changes in the proton signals. Hydrodynamic radii obtained from the dynamic LS data at infinite dilution for the cyclodextrins correspond well with dimensions determined using X-ray methods. Inverse Laplace transformation (ILT) allowed resolution of the relaxational modes from the cyclodextrin/pluronic complex and the excess cyclodextrin. The complexes formed with the DIMEB are shown to be significantly larger than the copolymer unimers, which may be due to accentuation of steric hindrance to flexing in the PPO block. With the inverse pluronic structure, on the other hand, the complex is smaller in radius than the unimer. At temperatures above which the copolymer forms micelles, addition of DIMEB inhibits both cluster formation and micellization of the pluronics and also prevents network formation with the inverse pluronic, whereas the trimethyl analogue (TRIMEB) does not have this effect.

An automatic high-precision ultrasonic system with the corresponding ultrasonic cell is described to measure simultaneously the speed of sound and the attenuation as a function of frequency. The technique is based on the pulse-echo method and is designed to detect small structural changes in liquids, when an external variable is changed. The precision of the technique is limited by the stability of the temperature, which was kept constant within ±0.5 mK. The method, which permits one to obtain the absolute value of the velocity as well as the attenuation with respect to the solvent, is fully automated for the whole variation of the external variable, which added to its fast response permits easy use in dynamic processes.