1. Department of Chemistry “G. Ciamician”, University of Bologna, via Selmi 2, 40126 Bologna, Italy, Institute of Polymer Chemistry, Polish Academy of Sciences, 41-800 Zabrze, Poland, Department of Chemistry, Silesian Technical University, 44-100 Gliwice, Poland, and Polymer Engineering Co. Ltd., Burnaby, B.C. V5B 3A6, Canada