@article{roman_thoppey_gorga_bochinski_clarke_2013, title={Maximizing Spontaneous Jet Density and Nanofiber Quality in Unconfined Electrospinning: The Role of Interjet Interactions}, volume={46}, ISSN={["1520-5835"]}, DOI={10.1021/ma4013253}, abstractNote={The interplay between an applied electric field and fluid properties was studied for a polymer solution forming high quality nanofibers via electrospinning. Unconfined electrospinning—in which a fluid thin film or bath exposed to an electric field spontaneously generates many parallel fiber-forming jets—is a practical approach to achieving a high fabrication rate of quality nanofibers as compared to traditional single-needle electrospinning. The density of fiber-forming jets is controlled by surface tension effects at the lowest applied voltages but by jet-to-jet interactions as the voltage amplitude is increased, resulting in an intermediate operating voltage level at which jet number is maximized. This general result is applicable to electric-field-driven fluid instabilities in a wide range of systems. The optimal voltage level occurs when interjet interactions begin to solely determine the characteristic jet spacing, and in this regime, compression of the cone-jet slightly chokes the feed rate, allowin...}, number={18}, journal={MACROMOLECULES}, author={Roman, Michael P. and Thoppey, Nagarajan M. and Gorga, Russell E. and Bochinski, Jason R. and Clarke, Laura I.}, year={2013}, month={Sep}, pages={7352–7362} }
 @article{stevens_skau_downen_roman_clarke_2011, title={Finite-size effects in nanocomposite thin films and fibers}, volume={84}, ISSN={["1550-2376"]}, DOI={10.1103/physreve.84.021126}, abstractNote={Monte Carlo simulations of finite-size effects for continuum percolation in three-dimensional, rectangular sample spaces filled with spherical particles were performed. For samples with any dimension less than 10-20 times the particle diameter, finite-size effects were observed. For thin films in the finite-size regime, percolation across the thin direction of the film gave critical volume fraction (p(c)) values that differed from those along the plane of the film. Simulations perpendicular to the film for very thin samples resulted in p(c) values lower than the classical limit of ∼29% (for spheres in a three-dimensional matrix) which increased with film thickness. For percolation along thin films, while holding film thickness constant, p(c) increased with increasing sample size, which is a modification of the finite-sized scaling effect for cubic samples. For samples with a large aspect ratio (fibers) and a finite-sized cross-sectional area, the critical volume fraction increased with sample length, as the sample became quasi-one-dimensional. The results are discussed in the context of adding volume along or perpendicular to the percolation direction. From an experimental perspective, these findings indicate that sample shape, as well as relative size, influences percolation in the finite-size regime.}, number={2}, journal={PHYSICAL REVIEW E}, author={Stevens, D. R. and Skau, E. W. and Downen, L. N. and Roman, M. P. and Clarke, L. I.}, year={2011}, month={Aug} }