Magnetic and Surface Properties of Metallophthalocyanines (M = Cu, Fe) Grafted Polyethylene

To employ advantageous tunable magnetic properties of metal phthalocyanines (Pcs) in practical devices it is necessary to bind them to solid substrates. A simple method to bind Cu(II) and Fe(III) sulfonated phthalocyanines on a plasma-treated surface of polyethylene (PE) is proposed. Formation of reactive centers (radicals) on the PE surface after plasma treatment was observed in electron-spin resonance (ESR) spectra at 330 and 350 mT. The signal at 350 mT disappears after grafting of the Pcs, which suggests the radical is spent on formation of a chemical bond. Successful grafting of Pcs was also confirmed by X-ray photoelectron spectroscopy and SEM-EDS measurements. In UV–vis spectra Q and B bands typical for the π–π interaction in Pcs were observed at 620 and 340 nm, respectively. Splitting of the Q band occurred due to a reduction in the symmetry of the peripherally substituted Pcs. Interestingly, a lower concentration of CuPc solution during the grafting process leads to a higher amount grafted to the surface. In the case of FePc the optimum grafting concentration is higher. The ESR spectra of PE samples with grafted FePc were similar to the bulk Pcs with the high-spin state (S = 5/2) of d5 Fe(III) ions.