Complexing properties and structural characteristics of thermally sensitive copolymers of N-vinylpyrrolidone and N-vinylcaprolactam

The interaction of thermally sensitive copolymers of N-vinylpyrrolidone (VP ) and N-vinylcaprolactam (VC) with small molecules having different chemica l structures (8-anilinonaphthalene-1-sulphonic acid magnesium salt dihydrat e, acridine orange, phenol, and sodium dodecyl sulphate) in aqueous solutio ns was studied by luminescent methods. The interaction of these copolymers with acridine orange was studied at different temperatures. It was establis hed that the complexing ability of VP-VC copolymers even at a low content o f VC units exceeds that of poly-N-vinylpyrrolidone. At a high content of VC units, and a low content of VC units, the complexing ability of VP-VC copo lymers was found to be higher than that of poly-N-vinylcaprolactam. It is s hown that the change in functional characteristics of VP-VC copolymers is d etermined by changes in the structural organization of VP-VC macromolecules and by increasing intramacromolecular interactions between nonpolar groups . Intramacromolecular structurization occurring during temperature increase and complexation is manifested very distinctly by changes in nanosecond dy namics of macromolecules. Nanosecond relaxation times characterizing intram olecular mobility of macromolecules with increasing temperature and in comp lexation with phenol and surfactant ions were determined. (C) 2000 Elsevier Science Ltd. All rights reserved.