Even Better Than Superior To Nature?

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Discussion Overview

The discussion revolves around the feasibility of creating synthetic carbon structures, specifically focusing on the existence and properties of carbon chains with alternating double bonds (C=C=C) and their potential applications in materials that mimic or exceed the adhesive properties of gecko setae. The scope includes theoretical chemistry, material science, and potential applications in engineering.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant proposes the idea of carbon chains ending in C=C=C strings, questioning their existence and hydrophobic properties.
  • Another participant doubts the stability of such chains, suggesting that they would likely form more stable allotropes like graphite or diamond instead.
  • Concerns are raised about the reactivity of carbon atoms in such configurations, with a suggestion that long chains of C=C would be chemically unstable.
  • There is a discussion about the theoretical limits of carbon fiber diameters, with one participant stating that 0.4 nm is the smallest known diameter for stable carbon nanotubes.
  • Participants reference external sources to support their claims about carbon allotropes and atomic sizes.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility and stability of C=C=C carbon chains, with no consensus reached on their existence or properties. The discussion remains unresolved regarding the potential for creating such structures.

Contextual Notes

Participants note limitations in current manufacturing techniques for fibers at the atomic scale and the inherent instability of proposed carbon structures, which may affect the viability of the discussed applications.

SkepticJ
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A few months ago I linked to this development in the creation of synthetic setae far better than those of geckos: http://www.wired.com/news/medtech/0,1286,68639,00.html

In the time since, I've done some research, corresponded with the team leader involved with the linked research and then came up with a new idea.
Ok, picture a rubber sheet, or eventually a flexible diamond-like carbon compound, on this sheet are setae, on the ends of the setae are spatulae, on the ends of the spatulae are carbon nanotubes, sizes ranging from 50nm or so in diameter down to 0.4nm(Allowing the majority of the spatulae's tips to be covered in nanotubes, without wasted space in between them.) Now for my idea, the carbon nanotubes end in C=C=C string hairs.
My question is, since I can't find anything on them, are there such things as C=C=C strings? Picture carbon atoms linked together like a pearl necklace. One atom in diameter, and of any required length.
Second question, if they exist, are C=C=C strings hydrophobic?
 
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I doubt there would be strings of =C=C=C=C= . . . C=C=.

There certainly is propadiene H2C=C=CH2, but there is no butatriene H2C=C=C=CH2, though there is butadiene, H2C=CH-CH=CH2.

I would expect the chains of =C=C= are rather chemically unstable, and either form the common graphite or diamond allotropes, or perhaps fullerenes.

See also - http://en.wikipedia.org/wiki/Allotropes_of_carbon (very limited discussion)

Some information about carbon allotropes included - http://en.wikipedia.org/wiki/Allotropy
 
Astronuc said:
I doubt there would be strings of =C=C=C=C= . . . C=C=.
There certainly is propadiene H2C=C=CH2, but there is no butatriene H2C=C=C=CH2, though there is butadiene, H2C=CH-CH=CH2.
I would expect the chains of =C=C= are rather chemically unstable, and either form the common graphite or diamond allotropes, or perhaps fullerenes.
See also - http://en.wikipedia.org/wiki/Allotropes_of_carbon (very limited discussion)
Some information about carbon allotropes included - http://en.wikipedia.org/wiki/Allotropy


Why?

Perhaps strings of Carbon[tri-bond]Carbon[tri-bond]Carbon[tri-bond]Carbon...?

Any other way you can think of to get hydrophobic hairs smaller than 0.4nm in diameter? How much smaller?
 
One cannot do C(tribond)C(tribond)C . . . since each carbon would have 6 bonds - and that would be extremely reactive.

Nature always tries to get to least energy, and long chains of C=C=C . . . would be unstable with respect to graphite which more easily obtained than diamond. If it were possible and easy, many folks would already be doing it.

http://hyperphysics.phy-astr.gsu.edu/hbase/particles/atomsiz.html

The carbon atom has a radius of approximately 0.22 nm, so that is the theoretical limit of a fiber - but that is one atomic diameter - and I do not see a manufacturing technique building fibers of 1 or 2 atomic diameters.
 
Astronuc said:
One cannot do C(tribond)C(tribond)C . . . since each carbon would have 6 bonds - and that would be extremely reactive.
Nature always tries to get to least energy, and long chains of C=C=C . . . would be unstable with respect to graphite which more easily obtained than diamond. If it were possible and easy, many folks would already be doing it.
http://hyperphysics.phy-astr.gsu.edu/hbase/particles/atomsiz.html
The carbon atom has a radius of approximately 0.22 nm, so that is the theoretical limit of a fiber - but that is one atomic diameter - and I do not see a manufacturing technique building fibers of 1 or 2 atomic diameters.

Hmmm, ok. Thanks for the help.

4 angstroms, or 0.4 nanometers, is the smallest known, and smallest theoretical as well, diameter of a carbon nanotube. So that's probably the smallest, stable carbon-only wire that can be done.
 

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