Poly(vinylamine) (2) and copolymers (3) resulting from various degrees of substitution (DS) with benzyl groups were synthesized. The viscosity of the polymers measured in Tris buffer (mu = 0.05 M) at different pH values decreases with the increase of the hydrophobic character, and 3 takes a very tight conformation for DS > 50%. A fluorescence study was carried out using potassium 2-p-toluidinylnaphthalene-6-sulfonate (TNS) as the hydrophobic probe. We showed the existence of an apolar microdomain which is at the origin of the solubilizing power of 3. The hydrolysis of p-nitrophenyl acetate (PNPA) carried out at 25 +/- 0.1-degree-C in Tris buffer solution (pH = 8.74; mu = 0.05 M) was accelerated up to 20-fold compared to the 2 catalyzed reaction. Fluorometry, in agreement with kinetic measurements, showed that the solubilizing power and catalytic properties increase with DS. From these remarks, it was concluded that the substrate is entrapped in the power microdomain and undergoes the nucleophilic attack of the vicinal NH2 groups. A kinetic study in the presence of cyclodextrin (CD) was carried out and resulted in an inhibition effect.