Association of perfluorocarbon containing water soluble polymers

High molecular weight water soluble poly(N,N-dimethylacrylamide) (PDMA) copolymers hydrophobically modified with 2-(N-ethylperfluorooctanesulfonamido)ethyl acrylate (FOSA) comonomer were prepared by free-radical copolymerization. Association of PDMA/FOSA copolymers was studied by fluorospectroscopy utilizing the perfluorocarbon containing fluorescent probe 1-(perfluorooctanoyl) pyrene (PFOP). The fluorescence emission spectra of PFOP in copolymer aqueous solutions show increased PFOP monomer emission with increasing copolymer concentration of PDMA/FOSA aqueous solutions. This reflects increased partitioning of the probe from the aqueous phase to the hydrophobic micellar environment of associated FOSA comonomer units with increasing copolymer concentration. Utilizing monomer emission intensities, critical association concentrations of the polymers were determined.; Addition of beta-cyclodextrin (β-CD) to solutions of PDMA-FOSA copolymer resulted in sharply decreased Brookfield viscosities at β-CD concentrations of the order of 10−4 M resulting in an approximate β-CD-FOSA binding constant of 5 × 104M−1 at 90% β-CD bound FOSA to 6 × 105M−1 at 99% β-CD bound FOSA, whereas the addition of β-CD to solutions of PDMA homopolymer had no effect on the Brookfield viscosity. The addition of ammonium perfluorooctanoate (APFO) surfactant to solutions of PDMA/FOSA copolymer resulted in an increase in Brookfield viscosities irrespective of the presence of β-CD.; Complex formation of β-CD with sodium 1-adamantanecarboxylate (SAC) in the presence of copolymer were monitored by viscometry. Sharply decreased viscosities observed upon addition of β-CD to copolymer solutions were reversed upon addition of SAC to the β-CD complexed copolymers giving complete recovery of the original viscosity. Hydrogels were formed by the addition of SAC to PDMA/FOSA/β-CD solutions and the release of methyl orange from 3–4.3 weight % copolymer hydrogels was monitored.