Electrospun Polyethylene Oxide / Cellulose Nanocrystal Composite 2 Nanofibrous Mats with Homogeneous and Heterogeneous

25 Electrospinning of polymer solutions or melts driven by a high26 voltage electric charge is a highly versatile technique that can be used 27 to generate continuous 1D polymeric fibers with diameters rang28 ing from several micrometers to tens of nanometers. Electrospun 29 nanofibrous materials possess a variety of interesting characteristics 30 such as small dimension, large specific surface area,wide-range poros31 ity, unique physicochemical property, and excellent flexibility for 32 chemical/physical surface functionalization. Hence, electrospun 33 nanofibrous materials not only are being used in research labora34 tories but also are increasingly applied in industry. Their applica35 tion includes, but is not limited to, optoelectronics, sensors, catal36 ysis, filtration, and medicine. They are of particular interest in 37 regenerative medicine and tissue engineering because nanofibers 38 can be potentially tailored to mimic natural extracellular matrix 39 (ECM) in terms of structure, chemical composition, and mechan40 ical properties. Electrospun polymeric nanofibers, however, are 41 not sufficiently strong for many applications because of low mole42 cular chain orientation along the fiber long-axis resulting from low 43 stretching forces in the process of fiber formation. During the past 44 several years, a large number of studies has been conducted to 45 improve mechanical properties of electrospun polymeric nano46 fibers. Incorporating nanoparticles into polymer matrices is one 47 technique that has been developed and used as one of the most 48 effective methods for reinforcing electrospun nanofibers. 9 49 Cellulose nanocrystals (CNCs), one of the strongest and stiffest