1. Chemistry Department; University of Ioannina; P.O. Box 1186 45110 Ioannina Greece
2. Laboratory of Polymer Chemistry and Technology; Department of Chemistry; Aristotle University of Thessaloniki; GR-541 24 Thessaloniki Macedonia Greece
3. School of Materials and National Graphene Institute; University of Manchester; Oxford Road Manchester M13 9PL UK
4. Department of Physics; University of Ioannina; 451 10 Ioannina Greece