[1] Chinese Acad Sci, Shanghai Inst Organ Chem, Lab Polymer Mat, Shanghai 200032, Peoples R China
[2] Univ Paris 06, Inst Curie, CNRS, Lab Phys Chim Curie,UMR168, F-75248 Paris 05, France
[3] Univ Paris 11, Lab Phys Solides, CNRS, UMR8502, F-91405 Orsay, France