Time resolved fluorescence anisotropy of basic dyes bound to poly(methacrylic acid) in solution

• Main Authors: Oliveira Hueder Paulo M. de, Gehlen Marcelo Henrique
• Format: Article
• Language: English
• Published: Sociedade Brasileira de Química 2003-01-01
• Series: Journal of the Brazilian Chemical Society
• Subjects: dyes; polyelectrolytes; PMAA; rotational diffusion; solvent friction
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532003000500007

Solutions of atactic poly(methacrylic acid), PMAA, with molecular weights in the range of (1.6 to 3.4) x 10(5) g mol-1, and labeled with the fluorescent dyes 9-aminoacridine or Nile blue were studied by photophysical measurements as a function of solvent viscosity and polarity. The conformational behavior of the PMAA chain segments around the fluorescent probe was reported by the change in the rotational diffusion of the dyes. Ethylene glycol swells the polymer chain compared with the more contracted conformation of PMAA in 50% water/ethylene glycol. The change in the rotational relaxation time of the dye bound to PMAA with the decrease of water content in the solvent mixture indicates a progressive expansion of polymer chain to a more open coil form in solution.