1. State Key Laboratory of Solid LubricationLanzhou Institute of Chemical PhysicsChinese Academy of Sciences Tianshui middle road 18 Lanzhou 730000 China
2. Chair of Macromolecular ChemistryFaculty of Chemistry and Food ChemistrySchool of ScienceTechnische Universität Dresden Mommsenstraße 4 01069 Dresden Germany
3. School of Chemistry and Chemical EngineeringShihezi University 832003 Shihezi China
4. Current address: Physik Department, TUM—Technische Universität München James-Franck-Straße 1 85748 Garching Germany