1 Mesoscopic Diffusion of Polyethylene Oxide in Pure and Mixed Solvents Xiong Zheng †,†† , Mikhail A. Anisimov †,†††,* , Jan V. Sengers † , and Maogang He †† † Institute for Physical Science and Technology and Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD 20742, USA †† Key Laboratory of Thermo,Fluid Science and Engineering, Ministry of Education, Xi’an Jiaotong University, Xi’an, Shaanxi Province, 710049, P.R. China ††† Oil and Gas Research Institute of the Russian Academy of Sciences, Moscow, 117333, Russia