1. College of Chemistry and Chemical Engineering College of Materials Science and Engineering College of Environmental Science and Engineering Institute of Biomedical Materials and Engineering Qingdao University Qingdao 266071 P. R. China
2. State Key Laboratory of Bio-Fibers and Eco-Textiles Qingdao University Qingdao 266071 P. R. China
3. School of Materials Science and Engineering Shandong University of Technology Zibo 255000 P. R. China