1. State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Renmin Street 5625, 130022 Changchun, Jilin, P. R. China, BASF Aktiengesellschaft, Polymer Physics, 67056 Ludwigshafen, Germany, Institut Laue-Langevin, F-38042 Grenoble, France, Basell Polyolefine GmbH, R&D, 65926 Frankfurt, Germany, and Physikalisches Institut der Albert-Ludwigs-Universität, 79104 Freiburg, Germany