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Branching In Electrospinning Of Nanofibers, Darrell Reneker
Branching In Electrospinning Of Nanofibers, Darrell Reneker
Darrell Hyson Reneker
Electrospinning of polymer nanofibers often begins with a single, straight, elongating, and electrified fluid jet that emanates from a droplet tip when the electric field at the surface is high enough. After some distance an electrically driven bending instability of the elongating jet occurs. For a polymer solution suitable for electrospinning, capillary instability does not cause the jet to become a spray of droplets. Under some conditions, a sequence of secondary jet branches emanates from the primary jet. This paper describes an experiment in which many closely spaced branches along the jet were observed during the electrospinning of a polycaprolactone …
Correlation Of Free Radical Copolymerization Behavior And Copolymer Properties With The Strength Of Pi-Pi Stacking Interactions Between Aromatic Fluorocarbons And Aromatic Hydrocarbons: Comparison Of The Copolymerization Behavior Of 2, 3, 4, 5, 6-Pentafluorostyrene With Styrene, 1-Vinylnaphthalene And 2-Vinylnaphthalene, Coleen Pugh
Coleen Pugh
No abstract provided.
Rupture Of Two-Dimensional Alkane Crystal, Ali Dhinojwala
Rupture Of Two-Dimensional Alkane Crystal, Ali Dhinojwala
Ali Dhinojwala
We have studied the breaking of a two-dimensional alkane crystal above the disordered melt using an oscillating bubble rheometer. Surface tension changes abruptly during the expansion and contraction cycle. We postulate that this is due to rupture of the 2D crystal at grain boundaries. The magnitude of the abrupt change in surface tension decreases with a decrease in the rate of change of bubble surface area with a power law exponent of 0.8. The interfacial area formed after rupture decreases with a decrease in rate. These results provide new insights in understanding defect-mediated rupture in confined geometry.
Template-Induced Enhanced Ordering Under Confinement, Mesfin Tsige
Template-Induced Enhanced Ordering Under Confinement, Mesfin Tsige
Mesfin Tsige
We report a surprisingly strong ordering of Si-(CH(3))(2) groups upon confinement between two surfaces, an oxidized poly(dimethyl siloxane) (PDMS(ox)) elastomer and a methyl-terminated self-assembled monolayer (octadecyltrichlorosilane (OTS)) on sapphire substrates. This enhanced ordering is induced by the template of ordered methyl groups of OTS and is not observed for other surfaces (fluorinated monolayers and sapphire substrates). This strong ordering is reminiscent of layering observed for confined symmetric molecules between two mica surfaces but was expected to vanish between rough macroscopic surfaces. These results provide new insights on confined structure at the interface between two solids and are important in the …
Confinement-Induced Ordering Of Alkanes Between An Elastomer And A Solid Surface, Ali Dhinojwala
Confinement-Induced Ordering Of Alkanes Between An Elastomer And A Solid Surface, Ali Dhinojwala
Ali Dhinojwala
We have studied the molecular structure of liquid alkanes confined between a flexible elastomeric poly(dimethyl siloxane) lens and a rigid sapphire substrate using surface-sensitive infrared-visible sum frequency generation spectroscopy. The reduction in the gauche defects suggests ordering of liquid alkanes under confinement. The cooling of confined liquid below the freezing temperature leads to crystallization with alkane molecules lying on the substrate with the symmetry axis parallel to the surface normal. This structure is very different from the bulk alkane crystals next to sapphire or air interfaces.