Water/polymer interactions in poly(amidoamine) hydrogels by 1H nuclear magnetic resonance relaxation and magnetization transfer.

Hydrated cross-linked polymers belonging to the family of poly(amidoamine)s were investigated by high and low resolution (1)H nuclear magnetic resonance techniques in order to obtain information on water/polymer interactions in the swollen state. (1)H spin-spin and spin-lattice relaxation time analysis, as well as magnetization transfer experiments, indicated that water and polymer proton pools are essentially uncoupled, with water molecules diffusing fast within the hydrogel structure and exchanging between "bound" and free sites. For the polymer characterized by the highest cross-linking degree, there is strong evidence of a beadlike structure resulting in higher network rigidity and hydrogel micrometric heterogeneity.