Enhanced adhesion and friction by electrostatic interactions of double-level Teflon nanopillars

Izadi, Hadi; Golmakani, Mehrnaz; Penlidis, Alexander

doi:10.1039/c2sm27329b

Cited by 25 publications

(86 citation statements)

References 59 publications

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“…Interestingly, simultaneous measurement of electric charges and adhesion forces revealed that CE-driven electrostatic interactions have a decisive contribution to the dry adhesion of geckos over these materials. Better insight into the role of CE-driven electrostatic interactions in gecko adhesion is not only very important for understanding the principles of the supreme adhesion of geckos [8,11], but also is fundamentally very crucial in the design and fabrication of synthetic fibrillar dry adhesives [12][13][14], which have been recently hypothesized to be largely affected by CE-generated electrostatic interactions [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Role of contact electrification and electrostatic interactions in gecko adhesion

Izadi

Stewart

Penlidis

2014

J. R. Soc. Interface.

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Geckos, which are capable of walking on walls and hanging from ceilings with the help of micro-/nano-scale hierarchical fibrils (setae) on their toe pads, have become the main prototype in the design and fabrication of fibrillar dry adhesives. As the unique fibrillar feature of the toe pads of geckos allows them to develop an intimate contact with the substrate the animal is walking on or clinging to, it is expected that the toe setae exchange significant numbers of electric charges with the contacted substrate via the contact electrification (CE) phenomenon. Even so, the possibility of the occurrence of CE and the contribution of the resulting electrostatic interactions to the dry adhesion of geckos have been overlooked for several decades. In this study, by measuring the magnitude of the electric charges, together with the adhesion forces, that gecko foot pads develop in contact with different materials, we have clarified for the first time that CE does contribute effectively to gecko adhesion. More importantly, we have demonstrated that it is the CE-driven electrostatic interactions which dictate the strength of gecko adhesion, and not the van der Waals or capillary forces which are conventionally considered as the main source of gecko adhesion.

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Section: Introductionmentioning

confidence: 99%

Role of contact electrification and electrostatic interactions in gecko adhesion

Izadi

Stewart

Penlidis

2014

J. R. Soc. Interface.

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“…An extra level of hierarchy has also been introduced through the fingering instability during polymer infusion (Izadi et al, 2013). …”

Section: Overview Of Criteria For Biomimetic Dry Adhesivesmentioning

confidence: 99%

Recent Advances in Nanostructured Biomimetic Dry Adhesives

Pattantyus-Abraham

Krahn

Menon

2013

Front. Bioeng. Biotechnol.

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The relatively large size of the gecko and its ability to climb a multitude of structures with ease has often been cited as the inspiration upon which the field of dry adhesives is based. Since 2010, there have been many advances in the field of dry adhesives with much of the new research focusing on developing nanoscale and hierarchical features in a concentrated effort to develop synthetic gecko-like dry adhesives which are strong, durable, and self-cleaning. A brief overview of the geckos and the hairs which it uses to adhere to many different surfaces is provided before delving into the current methods and materials used to fabricate synthetic gecko hairs. A summary of the recently published literature on bio-inspired, nanostructured dry adhesives is presented with an emphasis being placed on fabrication techniques.

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“…[26][27][28] The possible effectiveness of CE and in turn, of the generated electrostatic interactions on adhesive properties of SDAs, is mostly because of the achievable magnitude of the electrostatic force coming from CE; that is, electrostatic forces caused by triboelectric charging can be very large, [24,25,27,28] much larger than vdW forces which are traditionally considered as the dominant interfacial forces at contact of SDAs. [26][27][28] The possible effectiveness of CE and in turn, of the generated electrostatic interactions on adhesive properties of SDAs, is mostly because of the achievable magnitude of the electrostatic force coming from CE; that is, electrostatic forces caused by triboelectric charging can be very large, [24,25,27,28] much larger than vdW forces which are traditionally considered as the dominant interfacial forces at contact of SDAs.…”

Section: Introduction and Perspectivementioning

confidence: 99%

“…[26][27][28] The fabricated electrostatic-based SDA consisted of extremely high aspect-ratio nanopillars (200 nm in diameter; up to 45 mm tall) with a fluffy nanolayer of the same material on top (see Figure 1). [26][27][28] The fabricated electrostatic-based SDA consisted of extremely high aspect-ratio nanopillars (200 nm in diameter; up to 45 mm tall) with a fluffy nanolayer of the same material on top (see Figure 1).…”

Section: Introduction and Perspectivementioning

confidence: 99%

“…[26][27][28] The fabricated electrostatic-based SDA consisted of extremely high aspect-ratio nanopillars (200 nm in diameter; up to 45 mm tall) with a fluffy nanolayer of the same material on top (see Figure 1). [27,28] Although Teflon AF is not a proficient vdW interaction generator, like other fluoropolymers, its chains consist of highly electronegative fluorine-based units, which promote the trapping of electrons at its surface upon contact. [29] In fact, the very low surface energy of Teflon AF, which is usual for a fluoropolymer, is limiting its vdW interactions upon contact.…”

Section: Introduction and Perspectivementioning

confidence: 99%

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Polymeric Bio‐Inspired Dry Adhesives: Van der Waals or Electrostatic Interactions?

Izadi

Penlidis

2013

Macro Reaction Engineering

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With respect to the dry adhesion mechanism that geckos employ for their locomotion, it is commonly accepted that the adhesive performance of synthetic bio‐inspired dry adhesives results from the formation of van der Waals interactions at the tip or side of the dry adhesive fibrils with the substrate they are brought into contact with. However, what has been usually neglected in this connection is that electrostatic interactions may also be developed at the contact between any two materials via the familiar contact electrification (CE) phenomenon. Although CE is common and can have a large influence on interfacial interaction forces, its impact on adhesive properties of synthetic dry adhesives has been overlooked. Even so, recent reports on fabrication of polymeric dry adhesives, which can generate strong adhesion forces relying on electrostatic interactions coming from CE, have brought to light again the idea that charging the surface of dry adhesives, specifically polymeric ones, can play a very crucial role in their adhesive behavior. From this perspective, the main reasons that have caused the lack of attention to this concept and the possible contributions of CE in interfacial interactions of polymeric dry adhesives are thoroughly discussed in this current critical review.

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Enhanced adhesion and friction by electrostatic interactions of double-level Teflon nanopillars

Cited by 25 publications

References 59 publications

Role of contact electrification and electrostatic interactions in gecko adhesion

Role of contact electrification and electrostatic interactions in gecko adhesion

Recent Advances in Nanostructured Biomimetic Dry Adhesives

Polymeric Bio‐Inspired Dry Adhesives: Van der Waals or Electrostatic Interactions?

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