January
Chemistry World podcast - January 2012
1:05- Caffeine content of high-street espressos
5:08- A zombie reaction rises from the dead
7:53- Antony Williams discusses collating chemical data and the ChemSpider database
14:57- Crab shell used to create a transparent plastic
17:40- A homonuclear diatomic molecule with a permanent dipole
21:53- US Army research chemist Jesse Sabatini talks about his work making cleaner pyrotechnics
28:29- Making a self-cleaning glass using candle soot
31:40- The lightest material ever created
35:13- Trivia - What causes a hangover?
(Promo)
Brought to you by the Royal Society of Chemistry, this is the Chemistry World Podcast.
(End Promo)
Interviewer - Chris Smith
Happy New Year! With me this month are Laura Howes, Phil Broadwith and Patrick Walter. They'll be revealing how the espresso you pick up from one café could contain 600% more caffeine than an equivalent brew bought elsewhere. Also how soot has inspired a nano design for self-cleaning glass; and is this the lightest metal substance known to man?
Interviewee - Patrick Walter
This metallic structure is actually 10% lighter than the lightest aerogel, so it really is incredibly light material and the researchers have a great picture on it, which is quite a large piece of the material resting on top of the head of a dandelion.
Interviewer -- Chris Smith
Hello this is the Chemistry World podcast for January 2012 and I'm Chris Smith.
(Promo)
The Chemistry World Podcast is brought to you by the Royal Society of Chemistry. Look us up online at chemistryworld dot org.
(End Promo)
(1:05 - Caffeine content of high-street espressos)
Interviewer - Chris Smith
And first up, Patrick is quivering with excitement over this first story or perhaps it's just the caffeine.
Interviewee - Patrick Walter
No, if you're feeling a bit jittery today then perhaps, it's the coffee shop you brought your coffee from. So Alan Crozier at the University of Glasgow did a bit of a field trial. He went around 20 Glaswegian coffee houses and picked up an espresso from each of them. This wasn't just for like a massive coffee hit for one day for him. He had a scientific purpose behind it.
Interviewer - Chris Smith
Oh I'm pleased to hear that. I'm sure the funders of the study will also be equally pleased to hear that their money was being well spent. What does he do with it?
Interviewee - Patrick Walter
Right. He takes away, he dilutes in methanol and freezes it, just to preserve it and then he runs few HPLC tests so that's high pressure or high performance liquid chromatography.
Interviewer - Chris Smith
Looking for the caffeine.
Interviewee - Patrick Walter
Exactly. So he was looking for the caffeine content. So, what he discovered was quite a massive disparity in the levels of caffeine you find across coffees from different coffee shops.
Interviewer - Chris Smith
How big is the disparity?
Interviewee - Patrick Walter
So it ranged from 50 milligrams to 322 milligrams. It's a massive amount.
Interviewer -- Chris Smith
Three hundred?
Interviewee - Patrick Walter
322.
Interviewer -- Chris Smith
Well, that's a 600% difference?
Interviewee - Patrick Walter
Exactly yeah.
Interviewer - Chris Smith
Blimey! And these are all marketed as an espresso? That means they're marketed equivalently.
Interviewee - Patrick Walter
Yes, They're all marketed as espressos and the Food Standards Agency says that people should expect on average that an espresso should contain about 50 milligrams of coffee and really only one actually contained that amount, all the rest had higher amounts.
Interviewer -- Chris Smith
So who was the best performer? Where should real caffeine heads lightly head for in Glasgow?
Interviewee - Patrick Walter
So best performance depends on whether you're a pregnant woman or a caffeine seeker? In this case.
Interviewer - Chris Smith
No, for an addictive like me where would I go for my best hit then?
Interviewee - Patrick Walter
If you're a hopeless addict then, Patisserie Francois in Glasgow.
Interviewer -- Chris Smith
Which was a 300 milligram one?
Interviewee - Patrick Walter
Yep.
Interviewer -- Chris Smith
And what's about if I'm feeling I'm already incaffeinated to the extent of jitteriness, where should I go then?
Interviewee - Patrick Walter
Then Starbucks is your one. Only 50 milligrams apparently
Interviewer - Chris Smith
Okay. So how does this compare then with other recreational uses of caffeine? If I go out to a club, and I say I had a vodka and Red Bull and I sink a whole tin of, you know small tins of Red Bull, how much caffeine in there, for comparison?
Interviewee - Patrick Walter
Well oddly enough, a Red Bull, despite being marketed as an energy drink doesn't contain that much more caffeine than an espresso, 80 milligrams per can.
Interviewer -- Chris Smith
Wow, so actually some of these coffees are containing may be three or four times as much caffeine in one espresso.
Interviewee - Patrick Walter
You're getting a whole Red Bull's from maybe 50 mls of liquid.
Interviewer - Chris Smith
Gosh much cheaper to go and buy the coffee then?
Interviewee - Patrick Walter
Exactly yes.
Interviewer -- Chris Smith
So, what do these guys say about this in Glasgow?
Interviewee - Patrick Walter
Well they do have their concerns. The Food Standards Agency recommends that pregnant woman shouldn't have more than 200 milligrams of caffeine per day. This also goes to children, but I don't have that many children who drink espresso.
Interviewer -- Chris Smith
Are they suggesting there should be some kind of regulation then in the same way that you buy a packet of cigarettes and it says this contains x numbers of milligrams of nicotine, and x number of milligrams of tar, should we know how high, medium and low tar coffee?
Interviewee - Patrick Walter
They haven't gone so far as to recommend that. They're recommending sort of further studies. I mean, as they say, it's just 20 coffee shops throughout Glasgow, but they say it probably is something that extrapolates pretty well to the rest of the country. But they're saying more research is obviously needed to assess caffeine levels across a much wider area.
Interviewer - Chris Smith
Are there any upsides too?
Interviewee - Patrick Walter
Upsides?
Interviewer - Chris Smith
Having a bigger caffeine hit?
Interviewee - Patrick Walter
If you're having a bigger caffeine hit, then it's likely that the antioxidant levels will be higher, so the Patisserie Francois espresso contain roughly the same level of antioxidants as did caffeine and if this kind of pattern holds then Starbucks one contains a lot less of the antioxidants too.
Interviewer - Chris Smith
So, a quivering jelly maybe, but protected from oxidative damage definitely will be too.
(5:08 - A zombie reaction rises from the dead)
Interviewer - Chris Smith
Phil too much coffee might as well turn you into a zombie, put us out of our misery.
Interviewee - Phillip Broadwith
Yes Chris. Well hopefully, the zombie that I'm talking about isn't going to try and eat your brains, but it does certainly come back to life. This is a group of Japanese high school students, in fact who were doing an experiment in class using oscillating reactions, a very famous one called the Belousov-Zhabotinsky reaction.
Interviewer - Chris Smith
What is one of those?
Interviewee - Phillip Broadwith
Well, oscillating reactions are a class of reactions that are often used in chemical demonstrations because they generally change colour and they'll flip from one colour and back again several times and that's down to the intricate interplay of several reactions that are all going on at the same time within that mixture.
Interviewer - Chris Smith
So, these kids in school, they're setting this up and what happened?
Interviewee - Phillip Broadwith
Okay. So, they set up lots of different experiments with different starting concentrations of reagents and most of those combinations will oscillate for a certain amount of time, and then stop and that'll be it. You've reached a kind of thermodynamic equilibrium. But they did find that at a certain concentration of starting reagents, the reactions would oscillate for about 10 hours or so and then they would stop for a period of somewhere between 5 and 20 hours and then they would restart oscillating again, admittedly at a slightly lower rate and whatever, but the crucial thing is that they restart, which means they haven't got to this thermodynamic equilibrium. They've reached some kind of kinetic trap.
Interviewer - Chris Smith
Or something else has changed in the products, maybe an inhibitor or something else that was previously not there, but which appears over time, because there's some kind of rate limiting step in the appearance of another chemical, a derivative of one of the products that takes time to produce, and that then rekindles the reaction.
Interviewee - Phillip Broadwith
Well, exactly Chris. I mean, the reaction that they were doing changes from red to blue and then it goes yellow in this dormant period, so there's obviously something else there going on and then it'll go back to the red-blue oscillation until it finally reaches its thermodynamic equilibrium.
Interviewer - Chris Smith
And they've published this?
Interviewee - Phillip Broadwith
Yeah, it's published in the Journal of Physical Chemistry.
Interviewer - Chris Smith
How are they going to take this forward to try and find out what those products are because that can't be easy because in these tubes you're going to have a mixture of loads of different chemicals and trying to freeze frame it there, I'm going to find out what is driving the reaction at this point, at this point, this point, that can't be terribly easy to do.
Interviewee - Phillip Broadwith
Yes. I think, I mean, you probably going to have to hand that onto someone with a bit more serious spectroscopic kit, but the discovery is, you know, it's one of those things, you know, if you continue to observe, then you're going to find things that may be other people haven't.
(7:53 - Antony Williams discusses collating chemical data and the ChemSpider database)
Interviewer -- Chris Smith
Phil Broadwith and I told them it might come in handy for that team in Japan is ChemSpider, a massive free database, containing the details of over 26 million chemical compounds. It's supported by the Royal Society of Chemistry and stewarded by the RSC's vice president for strategic development, Anthony Williams. He talked me through what it is designed to do.
Interviewee -- Anthony Williams
Scientists have gotten so used now to querying the web for information that they're interested in. For example, I have a chemical name and I would like to find out what the chemical structure might be. I would like to know some of the properties of that compound. Boiling point, melting point, crystal structure. Are there any articles about those chemicals that I'm interested in. So, when people are seeking information about chemicals, it can be very diverse in nature, but as commonly information that's been put into other database systems, extracted from literature articles etcetera etcetera. As with most queries that you make on the web, you can pretty easily get responses and fortunately you get many responses. It can be hundreds, thousands, millions of hits, based on a simple query and the question is how to get from your simple query out to the answer that you might be searching for?
Interviewer - Chris Smith
Hasn't this problem already been solved though by people who're doing molecular biology because if you look at them, they are generating billions of genetic letters every year that get added to databases and scientists all over the world read those gene codes and use them to inform their research and surely this is very, very similar isn't it?
Interviewee -- Anthony Williams
Biology data, certainly there's been a lot of investments in bioinformatics, a lot of grants have been put into this. There have been a lot of public domain systems that have been built and released, not so much for chemistry however. There really hasn't been as much as I put into it. A lot of the public domain data that one would expect to have been released lot sooner, didn't really start coming online until the efforts such as PubChem. So the bioinformatics world has really led the way. We're actually in catch-up mode. Small molecules have got a big issue in terms of the detail that is encoded into the way a molecule is represented, the number of synonyms a particular chemical can be labelled as has become very, very mixed in terms of quality in a different way than bioinformatics because they've actually set up systems online that are highly curated. The community has been working together up, not so much for chemistry.
Interviewer - Chris Smith
But I'm slightly struggling to understand why an organization for instance as powerful as the Royal Society of Chemistry, which connects chemists worldwide internationally and some of the top chemists, why there isn't a consensus like there is for biology to solve this problem. If chemists can solve the kinds of problems that they do routinely, why can't they solve this one?
Interviewee -- Anthony Williams
I think a lot of it is participation. So, I judged that most of this is no longer a technology issue. It is getting a community of chemists to participate in aggregating data together to making it available, to sharing it. If you think about the majority of chemicals that are available today from the life sciences world of course, many of these can be billion dollar drugs. Universities are funded by organizations today to do research into small molecules that could end up being patented; it could be worth an absolute fortune. So a lot of this information is actually held back. It's not so easily shared by the organizations themselves, certainly an academia; they protect a lot of that information. It's only with some of the shifts that we're seeing in the community now, into things like open notebook science and the more willingness from some of the academics to do so, that's when we're going to see the changes coming from
Interviewer - Chris Smith
So can you talk us through actually what ChemSpider is, what its strengths are, and how it will actually achieve some of these goals?
Interviewee -- Anthony Williams
ChemSpider at present is a database of organic molecules primarily. It contains 26 million unique chemicals. It's been aggregated from over 400 data sources on the web; people contributing data to us, depositing data. It's a crowd source system, but we've also done a lot of work ourselves to aggregate data. So for example, you as a scientist may come to the site, you may register, you could put in any chemical that you're interested in exposing to the public, you could deposit it yourself; it would show up almost immediately. In the background, the Royal Society of Chemistry is taking chemistry out of our articles and sharing it online, making it available. We're working with a number of collaborators to gather their data together. Once we have data online, one of the issues we run into is the diversity of quality from all of these different data sets because not every organization is focused on the issues of quality. So, we've provided an environment for cleaning the data, for annotating it, for curating it, to improve the data quality for everybody.
Interviewer -- Chris Smith
Now what about funding though because I know that with a lot of initiatives, where there is a database involved, there was initially huge enthusiasm about getting a database set up, but as Jimmy Wales has found with Wikipedia, there's enormous momentum to start with, keeping it running and keeping that momentum up though is another problem. So how do you sustain this?
Interviewee -- Anthony Williams
The Royal Society of Chemistry actually is putting money into the system with their own finances to develop a platform for the community. We do license access to the contents to other groups who would like to use it. We license access to services that utilize the database directly. The Royal Society of Chemistry is actually a charity, so we have a publishing arm, we're also a charity. So we see this as a big part of giving back to the community and we will continue to fund it. We are involved in grants, where we're being funded directly to enhance and develop the system and allow integrations into it that benefit other informatics platforms that are being built. Specifically there's a project right now called Open PHACTS that is part of the Innovative Medicines Initiative out of Europe.
Interviewer -- Chris Smith
And what are your stakeholders, as I suppose the end users you're targeting, what do they think of this?
Interviewee -- Anthony Williams
We had a lot of very positive feedback. We have a much larger development team than ever. We've got thousands and thousands of users hitting us every day now. A lot of the Royal Society of Chemistry's resources are starting to piece more and more into ChemSpider also. We're now hosting reactions. We're rolling out a spectral database capability early next year. We're now supporting the lone chemistry initiative, which is for secondary schools. It's just an enormous project that continues to expand in scope.
Interviewer - Chris Smith
Anthony Williams and you can find out more about ChemSpider, online at chemspider dot com. And now from spiders to crabs. Laura.
(14:57 - Crab shell used to create a transparent plastic)
Interviewee - Laura Howes
So this is a brilliant research out of Japan, where they've actually made a crab shell transparent.
Interviewer - Chris Smith
Is this part of the Japanese obsession with seafood or is there another application to this?
Interviewee - Laura Howes
Well, I think it's a little more interesting than that. So this is research out of Kyoto University where they're looking at making bio-nanocomposites. So, people are looking at using biomaterials into putting them into composite materials to use this straight from the properties of the biomaterial but combining it with other things being able to control various, sort of, mechanical and physical properties.
Interviewer - Chris Smith
So, the crab shell was a convenient scaffolding or convenient material to test out.
Interviewee - Laura Howes
Precisely. So one of the main things that crab shells are made out of is chitin, which is quite a well known material and people want to try and make composites using chitin. So, the researchers took a crab shell, whacked it in some acid and some alcohol and cleaned off everything until all they were left with was the chitin and then they just put it in an acrylic resin monomer. So just soaked in and pulled it out, polymerized it, and what happened was as the polymerization happened, the whole thing became transparent. So you've got this material that is strong, but also transparent, which is.
Interviewer -- Chris Smith
Why is the chitin transparent in the acrylic? Is the refractive index the same in the two materials then, so light just goes straight through it?
Interviewee - Laura Howes
Oh it's do with the fact that as long as there's not too much of the chitin around, then it doesn't actually affect the refractive index of the plastic. So it's not so much that the chitin is transparent because if you look at the chitin shell on its own, then that's kind of opaque, but once you fill it with the resin and fill the whole scaffold, it becomes transparent.
Interviewer -- Chris Smith
What are the applications of this, could you then basically make something else out of chitin in a structure you did want and then use this trick to produce an acrylic replica, which is see through transparency. You could have all kinds of interesting optical wave guides or so on.
Interviewee - Laura Howes
Precisely and in fact they then did powder up the chitin and make it into sheets and show again they could make the same sort of material. They've shown that this new composite has quite good optical properties even up to, sort of, 80 degrees centigrade, so similar composites that people are making start to lose their optical properties around 60-65 degrees centigrade. So, this is an improvement, which means that there's various, sort of, applications, this could be much better
Interviewer - Chris Smith
Okay. Just goes to show crabs are very, very useful.
(17:40 - A homonuclear diatomic molecule with a permanent dipole)
Interviewer - Chris Smith
Phil, tell us now about this interesting story which is very, very small compared with the crab. This is molecules that behave in a polar way even though they're made of two of exactly the same thing.
Interviewee - Phillip Broadwith
Yes Chris and according to the kind of standard way of thinking, that doesn't really work. If you've got a molecule that's made of two atoms of the same element, there's no difference in polarity, no difference in electronegativity between those two atoms. So there should be absolutely no electric dipole across them. But what has Hossein Sadeghpour at Harvard University and a couple of other groups in Germany have done is to take two atoms of rubidium and make a very special kind of molecule that actually does have a dipole.
Interviewer - Chris Smith
Why and how do you do that?
Interviewee - Phillip Broadwith
Okay. Well, I mentioned it as a special molecule. It's a very special molecule, it's called a Rydberg molecule and it's called that because one of the atoms of rubidium is in what's called a Rydberg state, this is a very highly excited electronic state. It's almost on the point of being ionized, but because it's kept very cold, you can keep that electron just attached to the atom and combine it with another atom that's just a normal rubidium atom to make this crazy molecule, which is about a thousand times larger than a normal molecule, but will hold itself together for long enough to do some spectroscopy
Interviewer -- Chris Smith
So, you have one which has got this highly excited electron and another one which has got a normal electronic configuration and because you've got that asymmetry, you've effectively got this polar behaviour.
Interviewee - Phillip Broadwith
Well it's not even as simple as that Chris. The prediction for these molecules in the state that the team has looked at is that they would be perfectly symmetrical electronically. They would not have a dipole. There is a different state that has been predicted to be accessed, which has a very large dipole, something like thousands of Debye compared to this which has only one Debye and that's about the same as normal organic molecules are normally about one or two Debye, sodium chloride in the gas state, about 10 Debye. So just to give you an idea, but this other state that has been predicted, which is called a trilobite state because if you look at the electron density distribution in the molecule, it resembles one of those fossils that you see called the trilobites, but a little bit of that state has mixed in with the spherically symmetrical state, and that gives it just enough asymmetry to give you this dipole, it's permanent dipole.
Interviewer -- Chris Smith
And it doesn't equalize across the molecule, I presume because the electrons owing to quantum rules can only occupy certain energy levels. So it's not trivial for it to just share out the extra energy symmetrically amongst the two.
Interviewee - Phillip Broadwith
Yes Chris there's no way according to quantum mechanics that the electron can transition between the two different states.
Interviewer -- Chris Smith
And how long does this stuff hang around for, how many pica seconds does it exist?
Interviewee - Phillip Broadwith
It's about 7 micro seconds.
Interviewer -- Chris Smith
Gosh as long as that? (Laughs)
Interviewee - Phillip Broadwith
Yeah yeah, just long enough to do some spectroscopy.
Interviewer -- Chris Smith
So what are the practical applications, if any of this, is it just academic or is this actually informing useful chemistry?
Interviewee - Phillip Broadwith
It's mostly kind of theoretical and fundamental chemistry and physics of matter, but the interesting thing about this is because the team has discovered that these two states are ever so slightly mixed, it's possible that this will give you a way to access the proper trilobite state which has a very, very large dipole, which then gives you some very interesting things to do with the physics of matter.
Interviewer -- Chris Smith
But given the polar things behave differently to non-polar things, couldn't you use this as sort of trick way of getting certain molecules to have transient properties and do some interesting chemistry, while they have that state and therefore make some reactions that otherwise wouldn't?
Interviewee - Phillip Broadwith
Yes that's entirely possible Chris. The problem is that they have to be really, really cold and confined on a surface.
Interviewer -- Chris Smith
So, the reaction rate would be really low anyway. (Laughs)
Interviewee - Phillip Broadwith
Yes, it wouldn't be the easiest thing in the world to do.
Interviewer -- Chris Smith
Damn, I thought I was onto something there. Thank you Phil.
Jingle
Interviewer -- Chris Smith
You're listening to Chemistry World with me Chris Smith. Still to come, why soot holds the key to clean windows and the lightest metal structure ever made.
(21:53 - US Army research chemist Jesse Sabatini talks about his work making cleaner pyrotechnics)
Interviewer -- Chris Smith
First though, to armaments and weapons. You wouldn't assume that making them environmentally friendly would be at the top of the military agenda, but it's something that US chemist, Jesse Sabatini deserves a medal for by replacing the toxic perchlorate oxidizing agents in flares with harmless nitrogen rich organic compounds. He's got something that's not only greener but better too.
Interviewee - Jesse Sabatini
I'm an organic chemist by training and so, you know, what we're finding is in pyrotechnics is traditionally an inorganic based field, but they're starting to use organic chemicals more and more to address some of these environmental hazards and you know, I guess the environmental intermediation efforts have been ongoing now for at least a decade actually, at least with the US army.
Interviewer -- Chris Smith
What was the big driver? why do you think they initiated this stance in the environment because forgive me but the US isn't known for its concern for the environment in many regards, so why the military?
Interviewee - Jesse Sabatini
There are two reasons. Number one, the old days of doing research in energetic materials was you just slapped something together, you made sure that it met a specification that the military wanted and you used it. There really wasn't any thought into the environmental ramifications at that time. Now we know a lot more about the science and about what chemicals are hazardous, what is dangerous, you know, we do try to be good stewards of the land and we want to try and reformulate these things. There's also a lot of regulatory pressure from the Environmental Protection Agency and some environmental groups. The big example that I will tell anybody is the perchlorate issue. Ammonium perchlorate, potassium perchlorate are probably the two biggest ones today that the EPA is really looking to regulate. They have passed a permissible limit of 15 ppb, parts per billion of potassium perchlorate or ammonium perchlorate that is allowed to be in ground water.
Interviewer -- Chris Smith
What are the risks of that chemical being in the ground water?
Interviewee - Jesse Sabatini
A): it contaminates public drinking supplies; but B): the iodide anion and the perchlorate polyatomic ion have roughly the same atomic radius and because of that you end up getting a competition that goes on in which iodide and perchlorate compete with binding of the thyroid gland and if that occurs, then the theory is you're disrupting the proper functioning of the thyroid gland and it can cause health complications. Now what's interesting is, you know, lot of pyro techniques for example contain potassium perchlorate, some of them in very large amounts. A lot of our training simulators, which we, you know, which are used to prepare soldiers for battle contain a lot of potassium perchlorate. And what happens is when the EPA came out and crack down on the perchlorate and established the permissible limit at 15 ppb, soldiers were unable to train with perchlorate containing items on some of these training sites in the United States.
Interviewer -- Chris Smith
I suppose, there's also the chance that the fact that the EPA and other regulators are imposing limits on people, they're making us have a rethink about many of these things, we may actually discover better ones because we stopped just using the same old technology, it forces us to think originally and up pop new inventions that turn out to be much superior.
Interviewee - Jesse Sabatini
Yeah and I think you make a very good point there. The initial formulation development that we have done here had done exactly what you have alluded to. We've taken out perchlorate; we've reformulated some of these formulations, like for example, some handheld signal formulations that I have been doing using these high nitrogen compounds, as perchlorate replacements, these things just give away nitrogen gas. It's benign and we're getting longer burn times, we're getting brighter outputs in terms of, you know, how bright does this thing actually burn or how bright is this thing to the viewer and that has good impacts not only to the military in the field, but also the civilian fireworks sector, I suppose, could also benefit from this as well and we're also finding that the sensitivities of these. What is the sensitivity to impact or friction or electrostatic discharge is also lower when we're taking out the perchlorate and that too is important when we start talking about the safety in handling of these materials.
Interviewer -- Chris Smith
What is the chemistry behind this though? What have you had to do in order to make these quite dramatic changes?
Interviewee - Jesse Sabatini
It wasn't just the perchlorate that was bad. It was also the binder system that we use. The purpose of a binder is to prevent the segregation of oxidizers in fields and the current binder that was used was Laminec binder, it's a polyester binder that is a single point failure. It's only available through one company in the United States. So the first thing we had to do was to introduce a new binder system that was widely available commercially and one that was also viewed as being non-toxic and we did. We replaced the Laminec binder with an epoxy based binder system that was proven to be not environmentally hazardous or non-toxic in its polymerized form. Of course taking out the perchlorates well, we had decided to go the high nitrogen route and the reason why is because when you take perchlorate out of a pyrotechnic ammunition you lose energy because perchlorates tend to decompose exothermically, but we knew that most of the energy from the high nitrogen compounds that we were using is based off of its high heated formation, it's copious nitrogen gas release and then we had to do some modification of burn times and luminous intensity. So, we had to prolong the burn time and the way we did that is we switched, we eliminated the fine magnesium powder with all the coarse magnesium powder and so, you know, we were really able to take advantage of several parameters, coarser particle sizes burning longer of course, high nitrogen compounds gave you a faster burn rate, but epoxy binders burn much longer than Laminec binders and so I think it was really interdisciplinary chemistry at its finest.
(28:29 - Making a self-cleaning glass using candle soot)
Interviewer - Chris Smith
Jesse Sabatinitalking to me from Picatinny Arsenal in New Jersey. And now from military flares to candles. Laura.
Interviewee -- Laura Howes
Okay. So if you're all the way up on a big skyscraper, it's a bit difficult to clean the windows. So people are trying to make self-cleaning glass, which is both water, super water phobic, super hydrophobic and also super oleophobic so also very repellent for oil. Doris Vollmer and colleagues at the Max-Planck Institute for Polymer Research in Germany has decided to use candle soot to make their coating.
Interviewer -- Chris Smith
Okay. Now that sounds rather a strange approach. Why have they done that?
Interviewee -- Laura Howes
It does sound like, a bit of a strange, sort of approach. We know that candle soot is black and horrible, you know but it's also known that candle soot is super hydrophobic, so water is easily repelled and rolls off the surface.
Interviewer - Chris Smith
Yes, indeed if you coat a surface with it and then drip water on to it, the water beads into lots of little bubbles and it runs off.
Interviewee -- Laura Howes
Exactly. Exactly then it rolls off, but obviously, soot is also not very strong. So as the water rolls off, it takes some of the soot with it and eventually.
Interviewer -- Chris Smith
It's also impractical to hold all of the panes of glass of your block of flats and a skyscraper over candle.
Interviewee -- Laura Howes
Well for two reasons, you don't want to make a factory full of candles, neither do you want your windows covered in soot.
Interviewer -- Chris Smith
Because you wouldn't see through them.
Interviewee -- Laura Howes
Exactly.
Interviewer -- Chris Smith
Okay. So how do they do it then?
Interviewee -- Laura Howes
They literally get a candle, light it, put a piece of glass over it and viola! You've got a coating that's super hydrophobic. What they then did though was they then used chemical vapour deposition to just cover those soot particles with some more silica.
Interviewer -- Chris Smith
Ah, so you're making a sort of glass sandwich. You've got glass, soot particles and then you're putting more silica, the raw material of glass on top to sandwich the soot in between.
Interviewee -- Laura Howes
Exactly, but at that point, it's still not see through. What they then did was calcined it, so they basically heated it up to about 200 degrees to burn off the candle soot because obviously candle soot is carbon hasn't quite a bit combusted into carbon dioxide and water.
Interviewer -- Chris Smith
And that can get out through the second layer of silica deposited on top.
Interviewee -- Laura Howes
Yeah, there's enough of a gap that it can escape and leave behind a transparent layer of these silica particles in the shape of the candle soot particles that they've cast onto.
Interviewer -- Chris Smith
So, the silica that's deposited takes on the shape of the soot that was there even though the soot is no longer there. It still silica, it's all in the shape.
Interviewee -- Laura Howes
Exactly. It's fixed. So it's all in the shape. So this is similar to some of the super hydrophobic surfaces that people have, where you've got sort of tiny pillars and that uses surface tension to stop the water from draining, but what they've shown is that not only is it super hydrophobic it's also super oleophobic, it repels oil as well.
Interviewer -- Chris Smith
Is this achievable on a mass manufacturing scale?
Interviewee -- Laura Howes
Well, when I spoke to Doris Vollmer, she said that it wasn't really so much for achieving on a mass scale, although potentially you could. If you think about what they've actually done, they've got a candle, they've done a bit of vapour deposition and then they calcined it, which is basically like putting it in an oven. So I mean, it's only a step up from something that you would do in your kitchen or urn.
(31:40 - The lightest material ever created)
Interviewer -- Chris Smith
That's amazing stuff. Well let's find out actually about another interesting micromaterial in terms of microfabrication and ultra structure. What have you got Patrick?
Interviewee -- Patrick Walter
So what I have here is a story about the lightest material ever constructed.
Interviewer -- Chris Smith
Lighter even than the infamous aerogel.
Interviewee -- Patrick Walter
Yes, so aerogels are gels that have been denuded of all their water. So, this leaves just finest a skeleton behind, but this metallic structure is actually 10% lighter than the lightest aerogels. So it really is incredibly light material and the researchers have a great picture on it which you can see on our web site, which is quite a large piece of material resting on top of the head of a dandelion.
Interviewer -- Chris Smith
This is not just the head as in the bit where the stalk ends. This is those fluffy little seeds that the dandelion clock.
Interviewee -- Patrick Walter
Exactly.
Interviewer -- Chris Smith
And it's resting on those. So this really is seriously light. How did they make it ? Who has done this?
Interviewee -- Patrick Walter
Right. So Tobias Schaedler at HRL Labs in Malibu and colleagues from other universities put it together by using a UV mask. The mask is able to direct UV light in specific ways and directions and what they did is they used a monomer solution and then by shining UV light through this mask they're able to polymerize the solution. So the solution is only polymerized where the UV light is going.
Interviewer - Chris Smith
So you've got a sort of three-dimensional effect.
Interviewee -- Patrick Walter
Exactly. And this is helped in part by the fact that as the UV light is doing its job and polymerizing the monomers, the polymers that's forming then acts as a guide that guides the UV light further into the solution.
Interviewer - Chris Smith
Oh that's clever. So the mask doesn't have to work in three dimensions because once you've got an initial spider's web of the polymer, it then in turn starts absorbing and allowing to pass through another areas, more UV light, so you get a repetition.
Interviewee -- Patrick Walter
It's a self-propagating wave guide.
Interviewer - Chris Smith
So that gives you the monomer polymerized, that's some kind of organic thing, some polymer. How do you then get to the metallic bit of it?
Interviewee -- Patrick Walter
So, what they've created there is a polymer mould. So it's like casting a brass statue perhaps. So, what they then do is they dip this mould into a catalyst solution and then take it out, dip into another solution this time, a nickel-phosphorus solution. So, in the nickel-phosphorus solution, the catalyst that's left over catalyzes the formation of this nickel-phosphorus structure, so this metal structure is deposited in a micro-lattice way.
Interviewer - Chris Smith
All around the original polymer.
Interviewee -- Patrick Walter
Exactly. So, you're left with these tiny, tiny tubes that are hundred micrometers in diameters and the walls of them are only a hundred nanometres thick. They're incredibly light and have extremely low density. So they're 99.99% air and they're just 0.9 milligrams per cubic centimetre, but the structural properties are quite impressive. So if you compress the micro-lattice down to half its size, it springs back with hardly any damage which is in complete contrast to the bulk alloy structure which is very brittle and breaks.
Interviewer -- Chris Smith
So, what do you think you could do with this?
Interviewee -- Patrick Walter
It looks like there could be loads of possible uses for it. I mean, things like shock absorption or perhaps sound proofing, ofcourse may be a structural material, I mean, they talk about using aircraft because it's so light.
Interviewer - Chris Smith
Thanks Patrick. And that picture of a piece of the metal perched on a fluffy dandelion head really is stunning. Take a look by searching the Chemistry World web site for metal micro-lattice if you want to find it. Now if all of this has been enough to make your head hurt, Phil's back with another cause for brain pain.
(35:13 - Trivia - What causes a hangover?)
Interviewee - Phillip Broadwith
Okay Chris. Well, given the time of year, we thought we'd ask what do you thought was the cause of a hangover.
Interviewer - Chris Smith
Well, too much whiskey usually.
Interviewee - Phillip Broadwith
Well yes Chris, but that's the kind of symptomatic cause, but it terms of chemistry, what is it people say it's dehydration or it's acetaldehyde or it's various other chemicals within the congener within the different alcoholic drinks.
Interviewer -- Chris Smith
Definitely true. If you buy a decent wine, it doesn't have too many negative effects. If you buy cheap stuff, it does and if you drink whiskey on top of a load of that wine it definitely produces very deleterious effects.
Interviewee - Phillip Broadwith
Well, yes Chris, and there's various researches have been done, I think it's mostly likely to be a combination of all of these factors, but it's certainly true that if you stick to something like vodka which has been triple distilled and then filtered to get rid of precisely those congener, you might not feel quite so
Interviewer - Chris Smith
Queasy.
Interviewee - Phillip Broadwith
Queasy. Although we would encourage all listeners of the podcast to drink responsibly, if you knew.
Interviewer - Chris Smith
Indeed so putting it all together basically, there are things that are already in the drink which are bad when you consume it so there are toxins that accumulate; there are also metabolic derivatives, acetaldehydes. So, when you break down ethanol, you make that and then other chemicals that are made in an onward breakdown from that. There's also the dehydrating effects. So it's everything coming together.
Interviewee - Phillip Broadwith
Yeah, it's kind of a perfect storm to make you feel absolutely horrible.
Interviewer - Chris Smith
Sink a couple of paracetamol, acetaminophen for American listeners and a couple of pints of water and you wake up the morning and you don't have half as many symptoms. Is that an evidence based practice?
Interviewee - Phillip Broadwith
Well I'm not going to pretend to be any kind of expert, but there is a certain amount of evidence that several of these chemicals are inflammatory so having something like an anti-inflammatory drug might help. I think the water will not do you any harm either.
Interviewer - Chris Smith
I think that's what they call wisdom in hindsight. That is it for this month. Thank you to our guests, Anthony Williams and Jessie Sabatini and also our regulars, Phil Broadwith, Laura Howes and Patrick Walter. The production was by Meera Senthilingam and I'm Chris Smith from thenakedscientists dot com. Best Wishes for a Prosperous 2012. Until next time Good Bye!!!
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The Chemistry World Podcast is brought to you by the Royal Society of Chemistry. Look us up online at chemistryworld dot org.
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