Journal of Colloid and Interface Science 278 (2004) 155–159 www.elsevier.com/locate/jcis Complex formation of linear poly(methacrylic acid) with uranyl ions in aqueous solutions Galiya S. Azhgozhinova a , Olgun Güven b,∗ , Nursel Pekel b , Artem V. Dubolazov a , Grigoriy A. Mun a , Zauresh S. Nurkeeva a a Department of Chemical Physics and Macromolecular Chemistry, Kazakh National University, Karasai Batyra 95, 480012 Almaty, Kazakhstan b Department of Chemistry, Hacettepe University, Beytepe 06532, Ankara, Turkey Received 27 February 2004; accepted 6 May 2004 Available online 9 June 2004 Abstract The complex formation of uranyl ions (UO 2+ 2 ) with poly(methacrylic acid) (PMAA) was investigated by potentiometric, conductometric, UV–visible, luminescence and FTIR spectroscopic, and thermal analysis methods. The stoichiometric ratio at complexation between polymer and uranyl ions was found to be equal to 2 polymer base units per uranyl ion. FTIR spectra of the PMAA–UO 2+ 2 complex confirmed incorporation of metal ions into the polymer and showed that the electrostatic interactions play a major role in complexation. An increase of emission intensity in luminescence spectra of uranyl ions suggests influence of conformation peculiarity of the poly(methacrylic acid) chain. The thermal degradation of polycomplex starts at lower temperature as compared to pristine PMAA that is due to the lower thermal stability of PMAA–UO 2+ 2 complex.  2004 Elsevier Inc. All rights reserved. Keywords: Luminescence; Metal–polymer complexes; Poly(methacrylic acid); Uranyl ions 1. Introduction The continuous increase of world needs for radioactive metals and problems of environmental pollution make the process of their recovery from different sources such as sea and wastewater very important. Many studies have therefore been devoted to investigation of different types of polymers for purification, concentration, separation processes, etc. Among them polyelectrolytes are the most widely used types of polymers due to the presence of ionic groups which form complexes with metal ions [1–5]. Therefore, the knowledge of association of metal ions with charged macromolecules is of significant importance for understanding their physico- chemical behavior. One of the suitable polyelectrolytes for these purposes is poly(methacrylic acid) (PMAA), the complexation ability of which was investigated under different experimental condi- tions. Mandel and Leyte [6] investigated Cu 2+ chelates of * Corresponding author. Fax: +90-312-297 7977. E-mail address: guven@hacettepe.edu.tr (O. Güven). PMAA by viscometric, electrophoretic, and spectrophoto- metric methods and demonstrated the binding of two car- boxylic groups by one Cu 2+ ion. Siegel et al. [7] calculated the complex formation constants K of the polycomplexes between PMAA as well as poly(acrylic acid) (PAA) and Zn 2+ , Hg 2+ , Pb 2+ , Mg 2+ , Tl + ions at different counte- rion concentrations and charges. A decrease of log K with increasing counterion concentration for these systems was observed. Razikov et al. [8] used ESR spectroscopy to study com- plexation of copolymers of methacrylic acid and N -(2- hydroxypropyl)methacrylamide with Cu 2+ ions in aqueous solutions. It was shown that the composition and structure of polycomplexes depend considerably on the content and nature of the functional groups, the degree of their neu- tralization, the molecular weight of ligands, and the initial composition of copolymers. Rivas et al. [9,10] showed that the affinity of copolymers of methacrylic acid and monomers containing ammonium and sulfonic groups of different com- positions toward metal ions of Cu 2+ , Co 2+ , Ni 2+ , Zn 2+ , Cd 2+ , Ag + depend on pH, functional groups, and charge of the metal ions. 0021-9797/$ – see front matter  2004 Elsevier Inc. All rights reserved. doi:10.1016/j.jcis.2004.05.010