Water-soluble copolymers. 36. Photophysical investigations of water-soluble copolymers of 2-(1-naphthylacetamido)ethylacrylamide

Copolymers with acrylic acid and methacrylic acid (MAA) are studied in aqueous solutions. An increase in excimer emission relative to monomer emission (I E /I M ) is observed upon increasing solution pH. The hydrophobic character of both the naphthyl chromophores and the pendent methyl groups of MAA and the effective decoupling of the naphthyl chromophores from the polymer backbone via a spacer linkage are responsible for this behavior. The effects of NaCl, urea, and Triton X-100 surfactant indicate that hydrophobic interactions among naphthyl chromophores are responsible for formation of an intramolecular «hypercoil» at high pH