Dynamic Behavior of Poly(-isopropylmethacrylamide) in Neat Water and in Water/Methanol Mixtures.

We investigate the collective dynamics of thermoresponsive polymer poly(-isopropylmethacrylamide) (PNIPMAM) in aqueous solution and in water/methanol mixtures in the one-phase region. In neat water, the polymer concentration is varied in a wide range around the overlap concentration *, that is estimated at 23 g L. Using dynamic light scattering (DLS), two decays ("modes") are consistently observed in the intensity autocorrelation functions for = 2-150 g L with relaxation rates which are proportional to the square of the momentum transfer.