Electrostatic fiber spinning or ‘electrospinning’ is a novel process for forming fibers with submicron scale diameters through the action of electrostatic force. The resulting nanofibers are collected as non-woven mats with extremely large surface to mass ratios which can be used in filtration, catalysis, and biomedical applications. Studies on electrospinning, however, have been limited to relatively simple polymeric systems and have begun to scratch at the surface of the nanofiber formation from complex systems for bioapplications. This talk will focus on some recent work in our group which addresses a) controlling cellulose microstructure via electrospinning with applications in enzymatic hydrolysis, and b) the development of magnetically active, conducting carbon nanofibers with hierarchical pore structures for biofuel cell applications. In the first biomass application, nonwoven mats of pure cellulose fibers were produced by electrospinning from solution.  We demonstrate that the cellulose microstructure such as degree of polymerization, crystallinity, and fiber diameters can be independently controlled by varying the solvent systems and processing conditions for eletrospinning. We will also present some preliminary results for hydrolysis of electrospun fibers with cellulase enzymes, and demonstrate the potential for kinetics studies with these fibers to provide insight into how the cellulose microstructure affects the rates of hydrolysis. In the study of the development of multi-fucational nanofibers, the precursors of magnetite and carbon fibers were electrospun, followed by careful thermal treatment. The resulting graphitic carbon nanofibers are magnetically active due to the formation of magnetite and exhibit hierarchical pore structures (nanoscale pores in the fibers and micronscale pores due to the fiber layout). These multi-functional carbon fibers can be applied to the development of a) magnetically switchable biofuel cells and b) magnetic transporters in complex media as required in brains.

Yong Lak Joo is an assistant professor in the School of Chemical & Biomolecular Engineering at Cornell University . He received his B.S. degree at Seoul National University in Korea in 1989, and received his M.S. and Ph.D. in chemical engineering at Stanford University in 1993 under the supervision of Prof. Eric Shaqfeh. His PhD thesis was on the experimental and theoretical investigation of purely elastic instabilities in viscometric flows. From 1993 and 1999, he was a senior research engineer at Hanwha Chemical Corporation in Korea . Prior to joining Cornell in 2001, Yong Lak Joo did two years of a postdoctoral research in the Department of Chemical Engineering at MIT, working with Professors Robert Armstrong and Robert Brown.

His research focuses on the integration of molecular details into a macroscopic level in polymeric materials processing. In particular, his group has been laying the foundation for new experimental and theoretical studies on nanofiber formation via electrospinning. He received a 3M Non-Faculty Award in 2004. He is a recipient of a National Science Foundation CAREER Award and a DuPont Young Professor Award. He also received an Excellence in Teaching Award in College of Engineering , Cornell University in 2006.