<p>We demonstrate here that the dewetting in a solvent-non-solvent mixture can be employed to achieve a facile, rapid and lithography-free fabrication of well-aligned nano to microscale 1-D polymer droplet arrays from electro-spun polystyrene (PS) nanofibers. These spherical microdroplet arrays can function as high-aspect-ratio nanolenses for super-resolved microscopy. We observed a Rayleigh-instability-driven morphological transition when thermally annealed electrospun PS fibers on a silanized glass substrate were dewetted with a solvent-water media. Instability in PS nanofibers is affected by the interactions occurring between the polymer and the substrate beneath it. We demonstrated that the dewetting kinetics and morphology of dewetted structures depends on whether dewetting is induced by thermal annealing, exposure to solvent vapor, or immersion in a liquid media of solvent and non-solvent. Intensified dewetting in liquid media not only results in significantly faster dewetting dynamics but also results in dewetting of thicker nanofibers, which remain stable under thermal annealing or solvent-vapor exposure. Moreover, the droplets produced by this method have significantly higher aspect ratio. The number density of these microdroplets can be further increased beyond any limit by sequential dewetting in a methyl ethyl ketone (MEK)-water mixture, enabling more closely packed arrays which cannot be achieved by the dewetting of thin films. This work provides a scalable and controllable approach for fabricating densely packed, aligned polymer structures with tunable diameters spanning nano to micro length scales, presenting new possibilities for accessible super-resolution imaging.</p> Graphical abstract <p></p>

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Solvent-induced instabilities in electrospun polystyrene nanofibers and 1-D micro droplet array fabrication

  • Nidhi Dubey,
  • Sushmitha Paulraj,
  • Sanjeev Kumar Mahto,
  • Ankur Verma

摘要

We demonstrate here that the dewetting in a solvent-non-solvent mixture can be employed to achieve a facile, rapid and lithography-free fabrication of well-aligned nano to microscale 1-D polymer droplet arrays from electro-spun polystyrene (PS) nanofibers. These spherical microdroplet arrays can function as high-aspect-ratio nanolenses for super-resolved microscopy. We observed a Rayleigh-instability-driven morphological transition when thermally annealed electrospun PS fibers on a silanized glass substrate were dewetted with a solvent-water media. Instability in PS nanofibers is affected by the interactions occurring between the polymer and the substrate beneath it. We demonstrated that the dewetting kinetics and morphology of dewetted structures depends on whether dewetting is induced by thermal annealing, exposure to solvent vapor, or immersion in a liquid media of solvent and non-solvent. Intensified dewetting in liquid media not only results in significantly faster dewetting dynamics but also results in dewetting of thicker nanofibers, which remain stable under thermal annealing or solvent-vapor exposure. Moreover, the droplets produced by this method have significantly higher aspect ratio. The number density of these microdroplets can be further increased beyond any limit by sequential dewetting in a methyl ethyl ketone (MEK)-water mixture, enabling more closely packed arrays which cannot be achieved by the dewetting of thin films. This work provides a scalable and controllable approach for fabricating densely packed, aligned polymer structures with tunable diameters spanning nano to micro length scales, presenting new possibilities for accessible super-resolution imaging.

Graphical abstract