@article{michielsen_zhang_du_lee_2011, title={Gibbs Free Energy of Liquid Drops on Conical Fibers}, volume={27}, ISSN={["0743-7463"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000295187300020&KeyUID=WOS:000295187300020}, DOI={10.1021/la202952e}, abstractNote={Small drops can move spontaneously on conical fibers. As a drop moves along the cone, it must change shape to maintain a constant volume, and thus, it must change its surface energy. Simultaneously, the exposed surface area of the underlying cone must also change. The associated surface energies should balance each other, and the drop should stop moving when it reaches a location where the free energy is a minimum. In this paper, a minimum Gibbs free energy analysis has been performed to predict where a drop will stop on a conical fiber. To obtain the Gibbs free energies of a drop at different locations of a conical fiber, the theoretical expressions for the shape of a droplet on a conical fiber are derived by extending Carroll's equations for a drop on a cylindrical fiber. The predicted Gibbs free energy exhibits a minimum along the length of the cone. For a constant cone angle, as the contact angle between the liquid and the cone increases, the drop will move toward the apex of the cone. Likewise, for a constant contact angle, as the cone angle increases, the drop moves toward the apex. Experiments in which water and dodecane were placed on glass cones verify these dependencies. Thus, the final location of a drop on a conical fiber can be predicted on the basis of the geometry and surface energy of the cone, the surface tension and volume of the liquid, and the original location where the drop was deposited.}, number={19}, journal={LANGMUIR}, author={Michielsen, Stephen and Zhang, Jinlin and Du, Jinmei and Lee, Hoon Joo}, year={2011}, month={Oct}, pages={11867–11872} }
 @article{du_michielsen_lee_2010, title={Profiles of Liquid Drops at the Tips of Cylindrical Fibers}, volume={26}, ISSN={["0743-7463"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000282936700041&KeyUID=WOS:000282936700041}, DOI={10.1021/la1031448}, abstractNote={In 1976, B. J. Carroll derived the equation to show that a symmetric liquid droplet sitting on a thin cylindrical fiber would acquire a bell shape at equilibrium. We have extended his derivation to describe a drop located at the top end of a vertical, cylindrical fiber. By minimizing the Gibbs free energy of the drop at the fiber tip, it was found that the drop consists of two portions, a spherical cap on the fiber tip and a full, symmetrical bell located on the fiber body adjacent to the fiber tip. The experimental verification of the predicted shapes was performed using water, ethylene glycol, and Kaydol drops on nylon cylindrical fibers. Only four parameters are required to obtain agreement between the theoretical shape and the observed shape: the drop volume, the fiber radius, the surface tension of the liquid, and the Young contact angle of the liquid on a flat surface of the same composition as the fiber.}, number={20}, journal={LANGMUIR}, author={Du, Jinmei and Michielsen, Stephen and Lee, Hoon Joo}, year={2010}, month={Oct}, pages={16000–16004} }
 @article{du_shintay_zhang_2008, title={Diameter control of electrospun polyacrylonitrile/iron acetylacetonate ultrafine nanofibers}, volume={46}, ISSN={["0887-6266"]}, url={https://publons.com/publon/7178321/}, DOI={10.1002/polb.21500}, abstractNote={AbstractElectrospinning is the process of producing ultrafine fibers by overcoming the surface tension of a polymer solution using high voltage. In this work, the effects of both solution properties (viscosity, conductivity, and surface tension) and operational conditions (voltage, feed rate, and spinneret‐collector distance), on the structure of electrospun polyacrylonitrile nanofibers, were systematically investigated. Iron acetylacetonate was added to the electrospinning solution to control fiber diameter by selectively adjusting solution properties. It was found that, with increased salt concentration, the fiber diameter increases and then passes through a maximum due to changes in solution viscosity, conductivity, and surface tension. In addition, the fiber diameter increases with increase in voltage, feed rate, and spinneret‐collector distance. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1611–1618, 2008}, number={15}, journal={JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS}, author={Du, Jinmei and Shintay, Samantha and Zhang, Xiangwu}, year={2008}, month={Aug}, pages={1611–1618} }
 @article{du_zhang_2008, title={Role of polymer-salt-solvent interactions in the electrospinning of polyacrylonitrile/iron acetylacetonate}, volume={109}, ISSN={["1097-4628"]}, url={https://publons.com/publon/7178336/}, DOI={10.1002/app.28396}, abstractNote={AbstractElectrospinning is a process of producing ultrafine fibers by overcoming the surface tension of a polymer solution with electrostatic force. In this study, iron acetylacetonate was added to a polyacrylonitrile solution, and the role of polymer–salt–solvent interactions in the electrospinning of the ultrafine fibers was investigated. The polymer–salt–solvent interactions were characterized by Fourier transform infrared spectroscopy; and the solution viscosity, conductivity and surface tension were measured in solutions with different salt concentrations. The formation of polymer–salt–solvent interactions increased the solution viscosity, conductivity, and surface tension values at low salt concentrations. At high concentrations, the solution viscosity and surface tension decreased, but the conductivity remained relatively constant. The polymer–salt–solvent interactions influenced the structures of the electrospun fibers by changing the balance among the solution viscosity, conductivity, and surface tension. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008}, number={5}, journal={JOURNAL OF APPLIED POLYMER SCIENCE}, author={Du, Jinmei and Zhang, Xiangwu}, year={2008}, month={Sep}, pages={2935–2941} }