Flat polymer ribbons and other shapes by electrospinning

Abstract

In addition to round nanofibers, electrospinning a polymer solution can produce thin fibers with a variety of cross-sectional shapes. Branched fibers, flat ribbons, ribbons with other shapes, and fibers that were split longitudinally from larger fibers were observed. The transverse dimensions of these asymmetric fibers were typically 1 or 2 m, measured in the widest direction. A correlation of the branches and bends, observed in high-frame-rate videography of the electrified jets of polymer solutions from which the ribbons and branched fibers were produced, suggest that these phenomena occur at scales ranging from around 1 mm to 1 m. The observation of fibers with these cross-sectional shapes from a number of different kinds of polymers and solvents indicates that fluid mechanical effects, electrical charge carried with the jet, and evaporation of the solvent all contributed to the formation of the fibers. The influence of a skin on the jets of polymer solutions accounts for a number of the observations. The observed shapes can be used as guides for the extension of mathematical or computer-generated models for the electrospinning process.

Electrospun polymer nanofibers: Mechanical and thermodynamic perspectives

“…Theoretical analyses 36,37 confirmed by experimental observations [38][39][40] have demonstrated that rapid evaporation yields sharp increases in polymer density at the fiber/vapor interface, consequently increasing fiber heterogeneity and porosity (Fig. 2).…”

Modeling of solvent evaporation from polymer jets in electrospinning

“…Solvent evaporation is also most likely the cause of the observed fiber skins, flat ribbons, and porous nanofibers in electrospinning. 17,18 Solvent evaporation from polymer coatings and films has been extensively studied based on Fick's law of mass diffusion. [19][20][21][22][23] For polymer jets in dry fiber spinning, a few studies have been conducted on the steady-state temperature and solvent concentrations in the jets.…”

Eletrofiação de Polímeros em Solução: parte I: fundamentação Teórica

“…Koombhongse et al [79] propuseram um mecanismo de formação de nanofitas durante o processo de eletrofiação. Os autores investigaram a formação das nanofitas de polieterimida.…”

“…Uma opção para se reduzir esta instabilidade é através da criação dos jatos secundários que darão origem as ramificações. Koombhongse et al [79] conseguiram verificar através de câmeras de alta velocidade a formação destes jatos secundários.…”