The applicability of ultrasonic attenuation measurements in the studies of the conformational behaviors of macromolecules in aqueous phase and hydrogel was studied with glutaraldehyde (Glu) cross-liked chitosan (CS) hydrogel containing poly(N- isopropylacrylamide )(PNPAM) and the aqueous solution of poly(methacrylic acid) (PMAA) as model sustems. It was shown that the conformations adopted by the macromolecules are well related to the values of the attenuation parameter(a). The open coil conformation corresponds to a smaller a value, and a compact coil conformation corresponds to a larger a value. It does not follow, however, that the more compact the coil comformation, the greater the a value. In fact, a too compact coil comformation corresponds to a uite small a value. Based upon these studies, it is predicted that the ultrasonic attenuation measurements may be developed into a simple. effective and non-destructive technique for the studies of mactromolecular behaviors in aqueous and hydrogel lhases.

Key words: CONFORMATION, POLYMETHYL ACRYLIC ACID, HYDROGEL, CHITOSAN