Pressure Effect on the Chain Shrinkage of Water Soluble Polymers Induced by Complexation with ANS

摘要

The effects of pressure on the binding of a hydrophobic compound (8-anilino-1-naphthalenesulfonate, ANS) to polyvinylpyrrolidone (PVP) in aqueous solution were investigated by fluorescence titration at a pressure range of 0.1-400 MPa. An elevation in pressure induced the dissociation of ANS from an oligomer PVP (molecular weight <6000), but enhanced its binding to a larger PVP molecule (MW >10,000). SAXS measurements demonstrated that the ANS-binding to the high-MW PVP chain was coupled to the shrinkage of the chain. The volume change determined for a PVP with a molecular weight of 2000 was +4.3 ml/mol, and that determined for a PVP with a molecular weight of 10,000 was -73 ml/mol.