Room temperature superconductor?

[UncleAl]

William A. Little at the Stanford Department of Physics proposed excitonic high temperature superconductors, [-C(Ph)=(Ph)C-]n

 

Phys. Rev. A 134 1416 (1964)

Phys. Rev. B 13 4766 (1976)

 

Little's 1964 PRA paper has been cited 840 times, including 16 times in 2005. There is sustained interest. Ph is phenyl, generic arenes and derivatives; chromophores, fluorophores...

 

Replace Bardeen-Cooper-Schrieffer large mass phonons (quantized lattice vibrations characterized by Debye temperature) with small mass excitons (quantized electron cloud polarizations) possessing characteristic energies around 2 eV or 23,000 K. Exciton-mediated electron pairing suggests superconductor critical temperatures exceeding 300 K even with weak coupling. Perhaps. Theory is elegant but experiment is definitive.

 

Two paper syntheses of a broad variety of Little's fully substituted high polymer polyacetylenes are possible. Modeling gives energies varying from -600 kcal/mole to +1200 kcal/mole for 16-mers (32-carbon polyacetylene backbones). Negative means stabilization.

 

HyperChem mm+ calculates 16-mers to minimized energy in acceptable run times.

 

http://www.hyper.com/products/Lite/lite20.html

 

HyperChem's energy baseline is the same array of individual isolated atoms. The numbers as such are debatable, but trends are strongly suggestive.

 

Energy,

kcal/mole Species

-------------------------

-2.677 benzene

+2.288 isopropenyl benzene

+73.231 32X isopropenyl benzene

+39.997 poly(diphenylacetylene) 16-mer

 

http://www.mazepath.com/uncleal/benzen1.png

http://www.mazepath.com/uncleal/pyrene1.png

Little's undoped polymers are helical...

http://www.mazepath.com/uncleal/rylnap2c.png

...with distortions possible. The para-connection is more interesting

 

One can pontificate about homopolymer ambient temp supercons, diblock copolymers as diodes, polyblock copolymers as quantum wells... Heck, let's make it,

 

benzil + McMurry coupling --> Little

Mechanical stirring or external vortex mixer. Magnetic stir bars might be counterproductive given the Meissner effect.

 

O=C(Ph)-(Ph)C=O --> [=C(Ph)-(Ph)C=]n

that is Little's [-C(Ph)=(Ph)C-]n with the brackets moved along one atom

 

Benzils are trivially obtainable in high yields from arene aldehydes. Direct couplng to product polymer is nice, but add one more prior step and the living polymerization is much nicer.

 

Somebody should look.

[C1ay]

and you have the top link on Google for "benzil superconductors" :shrug:

 

Welcome back to Hypo, I hope you had a good vacation.

[TheBigDog]

Welcome back Al.

 

Would the technology you are talking about be a candidate for producing cable to rebuild electrical infrustructure? Would it remove some of the other issues (not temperature) with superconduction such as field interference?

 

Bill

[UncleAl]

In 1964 it was utterly inconceivable that Little's polymers as a class - even the single simple example he published - could be chemically modeled much less synthesized. 2006 is different. Five major results can obtain,

 

1) The stuff cannot be synthesized despite optimism on paper. Crap happens. Ya gotta try.

 

2) The stuff can be made but it is only another organic metal (when p-doped). That's good enough for somebody's thesis.

 

3) It is a Type I superconductor at whatever temp. It would be quenched by very modest magnetic fields. Lots of noise but not much profit in it.

 

4) It is a Type II supercon at 40 K or above. Say it requires 20 teslas or more of magnetic field to quench it. That is commercial applications for MRI and instrument magnets, power plant supercon motors and generators, magnetic shielding, transportation magnetic levitation... Any of that is serious money.

 

5) It does what Little said it would do - a room temperature Type II supercon capable of conducting 100,000+ amps/cm^2 and unquenched by 20+ teslas of magnetic field. Every major power line, every electromagnet, every motor and generator... is obsolete. It would be great fun. Power storage suddenly has a whole new meaning.

 

$(US)50 HyperChem Lite models 1500 atoms with ease. Admittedly it is running in an AMD FX-55 with 2 GB of fast RAM, 24/7, isolated box with memory otherwise stripped... and about 100K-250K iterations are necessary to jiggle a polymer segment down to the bottom. It's only a tricked out desktop computer for under $3K when it was new, not academic or government super-hardware. The numbers work for Little's proposal. Those are perfectly reasonable molecules and some of them calculate as spectacular. Something is going on in there even in crude approximations.

 

Synthesis requiries an organic chemistry lab. The skill level is one year of undergrad organic chemistry. The quick and cheap one step syntheses are weekend hacks. They won't show on budget and you don't have to tell anybody if they fail.

 

I've talked with four Nobel Laureates - two who got it for discovering the catalyst needed for the elegant living polymerization, two who got it for discovering organic metals. "If it were a good prospect, somebody would have already tried it." It's 2-3 days in the lab, guys. America has died.

 

Next step is university untenured faculty, then local community colleges. I will eventually find somebody whose greed outweighs his fears. A local college has free labor (me) and free stuff (what's $500 for a broad range of starting materials?). All I need is borrowed infrastructure. I'm happy to share the Nobel as long as I get royalties on the resulting patents.

 

We'll see what happens over time. Knocking on doors is easy.

[Turtle]

I've talked with four Nobel Laureates - two who got it for discovering the catalyst needed for the elegant living polymerization, two who got it for discovering organic metals. "If it were a good prospect, somebody would have already tried it." It's 2-3 days in the lab, guys. America has died.

 

Next step is university untenured faculty, then local community colleges. I will eventually find somebody whose greed outweighs his fears. A local college has free labor (me) and free stuff (what's $500 for a broad range of starting materials?). All I need is borrowed infrastructure. I'm happy to share the Nobel as long as I get royalties on the resulting patents.

 

We'll see what happens over time. Knocking on doors is easy.

 

Any takers yet Al? Maybe I'm the last one you care to see take an interest in this fascinating work, but the bolded line of yours rings in my ears as the mantra of response to discovery.

Please keep us posted & if I (we) can help, just ask; even if it means staying out of the way.;)

[Turtle]

Synthesis requiries an organic chemistry lab. The skill level is one year of undergrad organic chemistry. The quick and cheap one step syntheses are weekend hacks. They won't show on budget and you don't have to tell anybody if they fail.

 

This has a good start at a Hypography record of some sort. The most original, unique, & likely to work 'let's try this' idea, while at the same time least responded to.

Keep at 'er Al; there's only six degrees of separation.:singer:

[UncleAl]

Phys. Rev. 134, A1416-A1424 (1964)

 

Little's proposed room temp exciton superconductor polymers are polyacetylene with its hydrogens replaced by blobs of loose electron density - e.g., polycyclic aromatic hydrocabons (arenes). Let's model five cases. We'll compare the calculated energy of a model compound (the isopropylidene arene) to the model short polymer/arene. If the model polymer is long enough vs. its ends, making it longer and recalculating won't change the numbers.

 

http://www.mazepath.com/uncleal/benzen1.png

Case I: The arene is a benzene. Cheap, fast, easy to synthesize on paper. Proof of synthetic concept in Pyrex. The 16-mer is stabilized by 1.039 kcal/mole-arene. Nothing special here.

 

http://www.mazepath.com/uncleal/pyrene1.png

Case II: The arene is pyrene. The 16-mer is stabilized by 13.841 kcal/mole-arene, the 21-mer by 13.863 kcal/mole-arene. Those are respectable numbers! Reactions with that activation energy proceed at room temp, so thermal noise may be a problem for superconductivity. Dry Ice at -77 C would be way interesting.

 

http://www.mazepath.com/uncleal/decacyc1.png

Case II: The arene is decacyclene. One more step adds to the polymer synthesis because the hydrocarbon, but not its aldehyde, is commercial. The 16-mer is stabilized by 25.252 kcal/mole-arene, the 21-mer by 25.435 kcal/mole-arene. That is a fat number! It might work to spec at room temp.

 

http://www.mazepath.com/uncleal/trinaph1.png

Case IV: The arene is trinaphthylene. This is a major synthesis starting from scratch, and expensive. The 16-mer is stabilized by 23.730 kcal/mole-arene, the 21-mer by 23.882 kcal/mole-arene. Decacyclene is better. However, fuse one more ring to each of its three arms and...

 

http://www.mazepath.com/uncleal/trianth1.png

Case V: The arene is trianthracylene. This is a major synthesis starting from scratch, and expensive. The 16-mer is stabilized by 34.316 kcal/mole-arene. If something worked before this, this will work better by a lot.

 

Little's speculation can be examined in Pyrex rapidly and for a marvelously small initial budget. Who would risk a weekend against $billions in licensing fees and royalites? Not academia,

 

"If it is any good, why hasn't somebody tried this before?"

 

Because physicists are not synthetic chemists and organikers are not physicists. Each set of funding agencies disparages the other discipline. Somebody must have the initial pair of big brass cajones - and none are to be had, not in America.

[Michaelangelica]

HIGH TEMPERATURE SUPERCONDUCTORS FOR MOBILE PHONES (Science Show:

09/12/2006)

Science Show - 9 December 2006 - High temperature superconductors for mobile phones

 

Mohan Jacob: That's right. The most popular superconductor material is operating at 92 Kelvin, and people try to actually get higher temperatures. 35 Kelvin is available but still it is not economical, so because of that people are still using this 92 Kelvin superconducting material.

[pgrmdave]

So, Unc, have you had any chance to test out the theory? Were you able to convince anybody to try?