1. Institute of Polymers, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
2. A.N. Nesmeyanov Institute of Organoelement Compounds of Russian Academy of Sciences, Moscow 119991, Russia
3. Institute of Molecular Biology, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
4. Centre of Polymer and Carbon Materials, Polish Academy of Sciences, Marie Curie-Sklodowskiej 34, Zabrze 41-819, Poland