Experimental evidence of slow dynamics in semidilute polymer solutions

The semidilute and concentrated solutions have been extensively investigated, but many questions are still unsolved. The present work, by means of photon correlation spectroscopy investigation on PMMA/acetone solutions, aims to add new information to the comprehension of the existence of a Song time contribution in the autocorrelation functions in semidilute solutions together with the fast diffusive modes. On the basis of our results we follow the idea of the intervention of elastic and stress relaxation of the network constituted by the entangled polymer chains. Moreover, we think that the observation of the slow modes can be attributed not only to the existence of entanglements but also to the effect that the monomer structure produces on the entanglement phenomenon itself.