Instability of dilute poly(ethylene-oxide) solutions

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Abstract
Using photon correlation spectroscopy we studied dilute solutions of polyethyleneoxide) in solvents such as methanol, pure water, or, a water isopropanol mixture. In alcohol the polymer is molecularly dispersed and the solution is stable over a period of time. On the other hand, aggregates seem to be present in water and to be time-dependent. For high values of the scattering wave vector K the inverse relaxation time is proportional to Kw where w = 2.95 which is in good agreement with the expected theoretical value for internal motions of the coil. At the lower K values the diffusion coefficient is found to evolve with time. This evolution is interpreted as a disentanglement of the initial aggregates