1. State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Graduate University of Chinese Academy of Sciences, Chinese Academy of Sciences, Changchun 130022, P. R. China; Department of Chemistry and Industrial Chemistry, University of Genova, Via Dodecaneso 31, 16146-Genova, Italy; and Laboratoire de Chimie et de Physique des Hauts Polymères (POLY), Université Catholique de Louvain, Place Croix du Sud 1, B-1348 Louvain-la-Neuve, Belgium