Host-Guest Interactions in Poly(N-isopropylacrylamide) Hydrogels

Measurements by differential scanning calorimetry (DSC), small-angle neutron scattering (SANS), and H-1 combined rotation and multiple-pulse NMR spectroscopy (CRAMPS) indicate that small aromatic molecules dissolved in poly(N-isopropylacrylamide) (pNIPA) hydrogels modify the temperature of the volume phase transition (TINT) in this system by partially shielding the NIPA side-chains from the water molecules and disrupting their organization. The strength of the interaction increases in the order pyrocatechol < phenol < resorcinol < phloroglucinol.