Absorption Properties of Polyurethane Hydrogels Based on Partial β-Cyclodextrin Nitrates and Polyethylene Glycol

Polyurethane hydrogels containing polyethylene glycol as a linear fragment and incomplete β-cyclodextrin nitrate as a cross-linking agent were synthesized. The polyols were cross-linked with 1,6-hexamethylene diisocyanate. The hydrogel swelling ratio was studied as a function of the content of partially nitrated β-cyclodextrin in the hydrogel, molecular mass of polyethylene glycol, and degree of substitution of hydroxy groups by nitrate groups in incomplete β-cyclodextrin nitrates. As the cyclodextrin nitrate content is increased from 13 to 44 wt %, the swelling ratio relative to the dry substance weight decreases from 9.5 to 2.3. An increase in the molecular mass of polyethylene glycol from 0.4 to 20 kDa leads to an increase in the swelling ratio from 1.6 to 5.1 for weakly cross-linked polyurethane hydrogels and from 1.2 to 2.8 for the thickly cross-linked hydrogels. The ability of the synthesized compounds to absorb Methylene Blue, Methyl Orange, and phenol was studied. Polyurethane hydrogels do not absorb Methylene Blue. The absorption of Methyl Orange and phenol depends both on the content of incomplete β-cyclodextrin nitrate and on the hydrogel swelling ratio. The synthesized polyurethane hydrogels are biologically compatible.