[1] Aristotle Univ Thessaloniki, Dept Chem, Lab Polymer Chem & Technol, GR-54124 Thessaloniki, Greece
[2] Aristotle Univ Thessaloniki, Solid State Phys Sect, Phys Dept, GR-54124 Thessaloniki, Greece
[3] Univ Manchester, Sch Mat, Oxford Rd, Manchester M13 9PL, Lancs, England
[4] Univ Manchester, Natl Graphene Inst, Oxford Rd, Manchester M13 9PL, Lancs, England
[5] Univ Ioannina, Dept Chem, POB 1186, GR-45110 Ioannina, Greece