Current work focuses on the directed self-assembly of block copolymers (BCPs) under thermal gradients. A processing method developed at NIST for BCP self-assembly--called cold zone annealing (CZA)--involves controllably transporting the film across a temperature gradient formed by a cold block (or “zone”), a hot block (Tg < THOT < TODT), and another cold block. While traditional processing methods (e.g., oven annealing) often require several days to achieve long-range order and orientation of BCP microdomains, processing by CZA takes only minutes to hours. This emerging technology has potential for use in next-generation hard disk manufacturing and other nanopatterning applications. Ongoing experiments are aimed at elucidating the physical processes behind the results observed and at combining CZA with other approaches such as chemical or topographical templating to further enhance ordering.
General research interests include polymer thin films, block copolymer self-assembly, zone refinement, scanning probe microscopy, X-ray and neutron characterization methods including reflectivity and small-angle scattering, layer-by-layer electrostatic self-assembly, controlled release, and gene delivery.
Awards and Honors
Sun, B., Jewell, C. M., Fredin, N. J., and Lynn, D. M. Assembly of Multilayered Films Using Well-Defined, End-Labeled Poly(acrylic acid): Influence of Molecular Weight on Exponential Growth in a Synthetic Weak Polyelectrolyte System. Langmuir 23, 8452 (2007).
Fredin, N. J., Zhang, J., and Lynn, D. M. Nanometer-scale decomposition of ultrathin multilayered polyelectrolyte films. Langmuir 23, 2273 (2007). (Cover Article)
Jewell, C. M., Zhang, J., Fredin, N. J., Wolff, M. R., Hacker, T. A., and Lynn, D. M. Release of plasmid DNA from intravascular stents coated with ultrathin multilayered polyelectrolyte films. Biomacromolecules 7, 2483 (2006).
Zhang, J., Fredin, N. J., and Lynn, D. M. Erosion of multilayered films fabricated from degradable polyamines: Characterization and evidence in support of a mechanism that involves polymer hydrolysis. J. Polym. Sci. Polym. Chem. 44, 5161 (2006).
Zhang, J., Fredin, N. J., Janz, J. F., Sun, B., and Lynn, D. M. Structure/property relationships in erodible multilayered films: Influence of polycation structure on erosion profiles and the release of anionic polyelectrolytes. Langmuir 22, 239 (2006).
Choi, S. I., Christensen, M. B., Fredin, N. J., and Pitt, W. G. Swellable coatings for hearing aid applications. J. Biomater. Appl. 20, 123 (2005).
Jewell, C. M., Zhang, J., Fredin, N. J., and Lynn, D. M. Multilayered polyelectrolyte films promote the direct and localized delivery of DNA to cells. J. Control. Release 106, 214 (2005).
Fredin, N. J., Zhang, J., and Lynn, D. M. Surface analysis of erodible multilayered polyelectrolyte films: Nanometer-scale structure and erosion profiles. Langmuir 21, 5803 (2005).
Ellison, C. J., Ruszkowski, R. L., Fredin, N. J., and Torkelson, J. M. Dramatic reduction of the effect of nanoconfinement on the glass transition of polymer films via addition of small-molecule diluent. Phys. Rev. Lett. 92, 095702 (2004).
NIST-NRC Postdoctoral Fellow
Electronics Materials Group
2008 to present: NRC Postdoctoral Research Associate, Polymers Division, NIST
2003-2008: Graduate Research Assistant, Department of Chemical and Biological Engineering, University of Wisconsin—Madison under the direction of Prof. David M. Lynn.
2002: NSF Research Experience for Undergraduates, Northwestern University under the direction of Prof. John M. Torkelson.
Ph.D., Chemical Engineering, University of Wisconsin—Madison, Madison, WI (2008). Dissertation: Physical Characterization of Erodible Polyelectrolyte Thin Films Fabricated from Plasmid DNA and Synthetic Polyamines Advisor: David M. Lynn
B.S., Chemical Engineering, Brigham Young University, Provo, UT (2003).