Construction of hierarchical structures by electrospinning or electrospraying

Zheng, Jie; Zhang, Haiyuan; Zhao, Zhiguo; Han, Charles C.

doi:10.1016/j.polymer.2011.12.018

Cited by 108 publications

(89 citation statements)

References 27 publications

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“…The presence of surface pores at high humidity ( > 50% RH) was hypothesized to be caused by vapor-induced phase separation (VIPS). 60,63,[68][69][70][71] Typically, a hydrophobic polymer, high volatility solvent, and a water-miscible solvent are necessary to facilitate VIPS. First, water vapor is absorbed into the jet due to the water-miscible solvent.…”

Section: Nezarati Et Almentioning

confidence: 99%

“…Literature reports of electrospinning a solution with these properties (hydrophobic polymer, water miscible solvent, and low volatility) have shown it is also possible to fabricate fibers with porous cores. 68,69 In order to provide a general overview of the role of humidity on fiber formation, the fiber morphologies for PEG, PCL, and PCU at 5%-75% RH are summarized in Table 3. First, the amount of fiber breakage for PEG and PCL at low RH was quantified, and a general trend of decreased humidity resulting in increased fiber breakage was observed.…”

Section: Effects Of Humidity and Viscosity On Fiber Morphologymentioning

confidence: 99%

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Effects of Humidity and Solution Viscosity on Electrospun Fiber Morphology

Nezarati

Eifert²,

Cosgriff‐Hernandez³

2013

Tissue Engineering Part C: Methods

353

210

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Electrospinning is a popular technique to fabricate tissue engineering scaffolds due to the exceptional tunability of fiber morphology that can be used to control scaffold mechanical properties, degradation rate, and cell behavior. Although the effects of modulating processing or solution parameters on fiber morphology have been extensively studied, there remains limited understanding of the impact of environmental parameters such as humidity. To address this gap, three polymers (poly(ethylene glycol) [PEG], polycaprolactone [PCL], and poly(carbonate urethane) [PCU]) were electrospun at a range of relative humidities (RH = 5%-75%) and the resulting fiber architecture characterized with scanning electron microscopy. Low relative humidity ( < 50%) resulted in fiber breakage for all three polymers due to decreased electrostatic discharge from the jet. At high relative humidity ( > 50%), three distinct effects were observed based on individual polymer properties. An increase in fiber breakage and loss of fiber morphology occurred in the PEG system as a result of increased water absorption at high relative humidity. In contrast, surface pores on PCL fibers were observed and hypothesized to have formed via vapor-induced phase separation. Finally, decreased PCU fiber collection occurred at high humidity likely due to increased electrostatic discharge. These findings highlight that the effects of relative humidity on electrospun fiber morphology are dependent on polymer hydrophobicity, solvent miscibility with water, and solvent volatility. An additional study was conducted to highlight that small changes in molecular weight can strongly influence solution viscosity and resulting fiber morphology. We propose that solution viscosity rather than concentration is a more useful parameter to report in electrospinning methodology to enable reproduction of findings. In summary, this study further elucidates key mechanisms in electrospun fiber formation that can be utilized to fabricate tissue engineering scaffolds with tunable and reproducible properties.

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Section: Nezarati Et Almentioning

confidence: 99%

Section: Effects Of Humidity and Viscosity On Fiber Morphologymentioning

confidence: 99%

Effects of Humidity and Solution Viscosity on Electrospun Fiber Morphology

Nezarati

Eifert²,

Cosgriff‐Hernandez³

2013

Tissue Engineering Part C: Methods

353

210

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“…These structures may require a two-step process, such as growing carbon nanotubes from nanoparticles doped in electrospun fibers, or single-step processes in which the humidity and solvent parameters are carefully controlled to generate nanometer sized pores along the fiber axis [157,158]. These hierarchical secondary structures, as opposed to smooth fibers traditionally generated by the electrospinning process, impart a variety of properties to the fibers, including superhydrophobicity or superhydrophilicity, improved catalytic, sensing, and ultra-filtration capabilities [159].…”

Section: Introductionmentioning

confidence: 99%

Hierarchically Structured Electrospun Fibers

Zander

2013

Polymers

130

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Abstract:Traditional electrospun nanofibers have a myriad of applications ranging from scaffolds for tissue engineering to components of biosensors and energy harvesting devices. The generally smooth one-dimensional structure of the fibers has stood as a limitation to several interesting novel applications. Control of fiber diameter, porosity and collector geometry will be briefly discussed, as will more traditional methods for controlling fiber morphology and fiber mat architecture. The remainder of the review will focus on new techniques to prepare hierarchically structured fibers. Fibers with hierarchical primary structures-including helical, buckled, and beads-on-a-string fibers, as well as fibers with secondary structures, such as nanopores, nanopillars, nanorods, and internally structured fibers and their applications-will be discussed. These new materials with helical/buckled morphology are expected to possess unique optical and mechanical properties with possible applications for negative refractive index materials, highly stretchable/high-tensile-strength materials, and components in microelectromechanical devices. Core-shell type fibers enable a much wider variety of materials to be electrospun and are expected to be widely applied in the sensing, drug delivery/controlled release fields, and in the encapsulation of live cells for biological applications. Materials with a hierarchical secondary structure are expected to provide new superhydrophobic and self-cleaning materials.

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“…Other examples of nonplanar hierarchically structured porous films are for instance the preparation of membranes for advanced filtration (also known as microsieves) composed by a hierarchical pore structure [208] or the construction of hierarchical structures by combination of electrospinning or electrospraying and breath figures [209][210][211].…”

Section: Complex Porous Surface Patterns: Ordered Multiscale Structuresmentioning

confidence: 99%

Breath Figures: Fabrication of Honeycomb Porous Films Induced by Marangoni Instabilities

Muñoz‐Bonilla¹,

Save²,

Billon³

et al. 2015

Polymer Surfaces in Motion

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The creation of porous polymer surfaces is a center of interest in current research. Porous surfaces possess extremely high specific surface areas, thus allowing their employment in a large variety of applications including electronics, photonics or biotechnology [1,2]. Pore size and distribution can play a major role in selective transportation or in insulation processes amongst others [3]. Those porous materials with cavities in the micrometer size range are interesting in catalysis, sensors, membrane preparation or as scaffolds for composite materials. Moreover porous materials with pore dimensions comparable to the wavelength of visible light are of interest as photonic band-gaps and optical stop-bands.Structures with micrometer or submicrometer dimensions can be created using different templating methods [4,5]. A large variety of approaches have been developed and employed to prepare microporous structured materials, including the use of templates such as ordered arrays of colloidal particles to produce inverse opal structures [6][7][8][9], from transformed polymeric sphere arrays [10,11], using emulsion droplets as templates [12], employing natural biological templates [13][14][15][16], by

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Construction of hierarchical structures by electrospinning or electrospraying

Cited by 108 publications

References 27 publications

Effects of Humidity and Solution Viscosity on Electrospun Fiber Morphology

Effects of Humidity and Solution Viscosity on Electrospun Fiber Morphology

Hierarchically Structured Electrospun Fibers

Breath Figures: Fabrication of Honeycomb Porous Films Induced by Marangoni Instabilities

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