Photophysical and Rheological Studies of the Aqueous Solution Properties of Naphthalene-Pendent Acrylic Copolymers

Document Type

Article

Publication Date

1991

Department

Polymers and High Performance Materials

Abstract

The effects of pH and the addition of various additives on the photophysical solution properties of the amphiphilic polyelectrolyte poly(2-(1-naphtylyacetyl)ethylacrylate-co-methacrylic acid) (NAEA-MAA) have been investigated. Unlike previously reported systems, an almost four-fold increase in excimer emission relative to monomer emission (IE/IM) is observed upon increasing pH and, consequently, the degree of ionization. An increase in the dilute solution viscosity of NAEA-MAA solutions with increasing degree of ionization indicates a somewhat expected transition from a compact coil to a more expanded coil at pH 7.5. The hydrophobic character of both the naphthyl groups of NAEA and the pendent methyl groups of MAA and/or the effective decoupling of the naphthyl chromophores from the polymer backbone via a spacer linkage are believed to be responsible, at least in part, for this behavior. Experiments utilizing urea, a water-structure breaker, indicate that at high pH hydrophobic interactions between naphthyl chromophores stabilize the copolymer in an intramolecular "hypercoil". Finally, synthesis of a hydrolytically stable analog of NAEA, necessary for further investigations, is outlined, and initial photophysical studies of its copolymers with methacrylic and acrylic acid are presented.

Publication Title

ACS Symposium Series

Volume

467

First Page

291

Last Page

302

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