1. Institute of Macromolecular Compounds, Russian Academy of Sciences; Bolshoi Prospect 31, St Petersburg 199004 Russia
2. Kuznetsov Siberian Physico-Technical Institute, Tomsk State University; Novosobornaya Square 1 Tomsk 634050 Russia
3. St Petersburg State University; 7/9 Universitetskaya Nab St Petersburg 199034 Russia
4. Department of Chemistry; Katholieke Universiteit Leuven; Celestijnenlaan 200D Heverlee 3001 Belgium