Role of hydrophobicity on structure of polymer-metal complexes

Metal complexation of a series of polymeric gels, with different degrees of ionization, prepared from acrylic acid and acryloyl amino acid monomers (CH2=CHCONH(CH2)nCOOH, where n = 4, 6 and 8), were investigated. The binding of Cu(II) ions to the gels was studied by means of swelling, quantitative determination of the amount of "bound" or complexed Cu(II), and EPR spectroscopy of Cu(II) complexes. Both the amount of Cu(II) and the structure of polymer-Cu(II) complex were influenced by the length of the pendent chain, i.e., "hydrophobicity" of the polymer gels. The metal uptake by the gels increases with increasing "hydrophobicity". Two types of polymer-Cu(II) complexes (monomer and dimer, respectively) were identified by EPR spectroscopy, their concentrations were found to be a function of hydrophilic-hydrophobic balance of the polymer gels.