Spatial and temporal scale of cooperative motions in supercooled liquids

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Ultrasonically induced birefringence was investigated in both polyelectrolyte and non-polyelectrolyte solutions. In non-polyelectrolyte.solutions, we investigated polystyrene (PS), polycarbonate, (PC) and polybutadiene. (PBD) solutions. We also measured ultrasonic absorption/ spectra in polyelectrolyte systems.In PS-toluene solutions, the birefringence signal was observed by the "nonbiased" and "biased" detection techniques. Two types of birefringence were induced ; one was due to linear and the other was due to nonlinear origins. The sign of birefringence of PS and PBD solution was negative but that of PS solutions was positive. It is reasonable that for the polymer chain, the orientation of the.segmental units of a main chain of the polymer will be perpendicular to the sound propagation. The difference in sign reflects the difference in the way of bonding of phenyl ring to the main chain structure. The linear relation was found between the segmental anisotropy of the polarizability and the birefringence per a segment.At molecular weight smaller than IxlO4, the birefringence increased with increasing molecular/weight but no molecular weight dependence was.observed when'it was larger than IxlO4.The birefringence of aqueous solutions of sodium polystyrene sulfonate (NaPSS) and tetramethyl ammonium polystrene sulfonate (TMAPSS) was larger than that of PS-toluene solutions. The.birefringence.of NaPSS and TMAPSS solutions. The difference can attributed to the ionbinding effect of the sodium ion.For the ultrasonic absorption spectra of TMAPSS solutions, the effect of NaCl and TMAC1 solutions was very small. Ultrasonically induced birefringence was more sensitive.to the change of the local conformation in the presence of the added salt that ultrasonic absorption was.