Poly(N,N-diethylacrylamide) (PDEA) possesses a lower critical solution temperature (LCST) in aqueous media. The solution properties of PDEA at various temperatures have been characterized with techniques such as rheology and dynamic light scattering. There is a decrease in the coil size before the phase transition due to a coil-to-globule transition. At the LCST, rheological and dynamic light scattering studies have also confirmed an aggregation phenomenon. This aggregation modifies the rheological properties of the polymer solutions. High frequencies hinder the phase-transition process and reduce the LCST of the polymers. (C) 2003 Wiley Periodicals, Inc.