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

Hydrated crosslinked polymers belonging to the family of poly(amidoamine)s were investigated by high and low resoln. 1H NMR techniques in order to obtain information on water/polymer interactions in the swollen state. 1H spin-spin and spin-lattice relaxation time anal., as well as magnetization transfer expts., indicated that water and polymer proton pools are essentially uncoupled, with water mols. diffusing fast within the hydrogel structure and exchanging between "bound" and free sites. For the polymer characterized by the highest crosslinking degree, there is strong evidence of a bead-like structure resulting in higher network rigidity and hydrogel micrometric heterogeneity.