Biomimetic cooperativity of hydration effect and effect of ethanol favorable for binding of bad organic sorbates were observed for their vapor sorption by cross-linked poly(N-6-aminohexylacrylamide) (PNAHAA) in the absence of liquid phase. The vapor sorption isotherms were determined for these systems by the static method of gas chromatographic headspace analysis at 298 K. The hydration above 0.09-0.13 g of H(2)O/(g of polymer) gives a cooperative increase in the PNAHAA binding affinity for benzene, cyclohexane, dioxane, and propanols up to a level which does not change by further hydration, indicating the polymer antiplasticization. Bad sorbates (dioxane, benzene) were observed to have a biomimetic cooperative influence on the binding of ethanol by the dried PNAHAA. This cooperativity does not occur in ternary systems with good nonhydroxylic sorbate acetonitrile.