These belong to a class of materials that we've done a lot of research in the lab, which are close to materials called shape memory polymers . So these happen to be materials called viscoelastomers, or they're materials that are in this transition state.So you can see that when I deform this dragon's wings, they're sort of slowly starting to recover.
in some cases. Polyethylene, polypropylene, nylons, like those squishy plastics. Their polymer chains and their chemistry are such that they can absorb a lot of impact. If a force comes in, they'll kind of deform.
And the next morning, the leaves were falling off. The polymers realign and the wiggle unfolds.
They actually didn't know anything that dissolved Teflon, but there was an even bigger problem at that point. - To polymerize TFE into Teflon, you can add a reactive atom or molecule that will hijack the first carbon double bond and start the reaction.
So you can see when we're pushing sort of on the pixel, you can push and hold, and you can measure sort of the lightest finger taps all the way to very, very Most polymers have a linear degradation profile, so if the well temperature's a few degrees off, it will degrade too quickly or too slowly.
were looking for new grounds to exploit um you know all these things had been perfected Under World War II um sonar lightweight polymers that you can use for netting and all and long lines and so forth so what happened in the late 40s early 50s is that a small group of fishermen from the Pharaoh Islands found
So it's favorable for at least one of these bonds to be at an angle. That makes the polymer wiggle in and out like a folded ribbon. So when you pull on a piece of rubber, first, all the polymers line up but then, each chain also unfolds.
All three bonds lined up is only one possible arrangement for any monomer. And one polymer usually has thousands of monomers. So after you release the stress, the chain goes from an improbable state, completely aligned to a more probable one, with wiggles.
Luckily, the symptoms were mild: fatigue, tightness of chest, headaches, and they would usually pass within 48 hours. It was called polymer fume fever. And even though it rarely happens today, it's why you should never overheat your Teflon pan to these temperatures, especially if you have pet birds at home,
And now they're chemically linked together. The start of a polymer chain. And once that goes now it has the ability to go react with all those other super glue hungry monomers and rapidly polymerize.
Tension is a pretty uni-directional force. And the polymer chains are able to deform enough. However, in shear you have a more dynamic set of forces going on.
By mixing in a little bit of this weak base, there are enough initiators to start the polymerization reaction, but not too many, so the polymer chains end up being longer. - We use DMSO, dimethyl sulfoxide, which, in no other context, would be used as an initiator,
- Just drop it here. - They take a polymer and they coat each side with carbon nanotubes that creates two effective conducting plates. So if you apply opposite charges to these plates, that pulls them together, stretching out the polymer .
It's got a foam. It's got a polymer . It has a fabric.
So broadly, what we do is we design these materials called shape memory polymers . I'm a polymer chemist from my PhD training at Georgia Tech. But then we use photo orthography to build flexible electronics onto these materials.
We've came up with some clever technology to sort of begin building devices upside down, and then we can transfer those devices off onto a polymer substrate. So it's sort of like if you were to take super glue and scotch tape.
But you have to be willing to do it And I'm going to read one other excerpt from the book, a woman named Ronee Hagen I interviewed. She was CEO of Polymer , which is an industrials company, multi-billion dollar company. And she told me this story about walking away.
Volcanoes could come back at any point, really big mega volcanoes. The self-healing polymer materials that I was mentioning before that are used in sealing ship holes, for example, and other industrial uses, those are biomimetic in the sense
to change the nature of their collagen. Collagen is a polymer , meaning it's built up of many, many copies of the same little molecule that link together. You can imagine twist ties that you wind together into something like a suspension bridge cable.
This is Al Maurice. He's a polymer chemist at Dow Chemical, and what he developed was the polymers to go from oil based paints to acrylic based paints. Now, if you're at a certain age, there was always oil based paints.
or some other form of image that can be output as a negative. The negative and the polymer plate are sandwiched together, it's exposed to light and where the light hits the photo ground on the polymer surface it hardens.
the light hits the photo ground on the polymer surface it hardens. And then the polymer plate is washed in warm water, it's a great thing because there is no toxic photo chemicals, it's a pretty benign process. And then the softer polymer material just rinses away and you are left with that relief surface, so it's a very wonderful, easy technology that means you don't have to set type and
And then the polymer plate is washed in warm water, it's a great thing because there is no toxic photo chemicals, it's a pretty benign process. And then the softer polymer material just rinses away and you are left with that relief surface, so it's a very wonderful, easy technology that means you don't have to set type and put the type all back in the box.
You start going kilometers in distance from end to end if each atom is the size of this tennis ball. - But the polymers aren't stretched out from end to end like that. Instead, they're all coiled up.
And the next morning, the leaves were falling off. - As you stretch the polymers , they start to align and stick together through weak intermolecular forces called Van der Waal's forces.
And then that molecule did the same, and the process repeated again and again until all of the TFE was trapped in these long chains. The gas had polymerized into polytetrafluoroethylene, forming this slippery powder. Plunkett just wanted to get rid of it because it ruined his experiment.
- And now if you sprinkle in initiator molecules, the initiator molecules also go into these bubbles. They start the polymerization reaction, so from TFE to Teflon. But now since it's happening spread all throughout these bubbles, the heat is evenly dissipated throughout the water, and no one explodes.
So he quickly went to wash it off with soap and water. But that accelerated the polymerization reaction, and his hands were stuck together. So he went to multiple medical professionals, and he got terrible advice.
This slows the rate of heat released, so there's not a significant temperature increase all at once. The longer polymers also break down much more slowly, so the wound has enough time to heal before the glue starts releasing toxins into the body. It's removed before that happens.
And finally, since the reaction is slower, there's more time for the monomers to float around and form longer polymers . These longer polymers can absorb stress better than shorter chains, meaning the glue can flex more without breaking. With the main problems addressed, Coover submitted an application to the FDA in 1964 for medical superglue.
This is the thing that reads the recipe. It's called RNA polymerase. Reads the recipe. Da da da da da!
And it makes a molecule called RNA. So RNA polymerase makes RNA. And that is the message from the gene that then a cell uses to build something.
So my background comes in this class of materials called shape memory polymers . And these polymers are plastics that can change shape and stiffness at different temperatures. So these are plastics.
you can hit a nail into a board with this banana. A lot of polymers , when they get really cold, get really hard and stiff. When they get really hot they melt or they get very soft.
A few of these--a very few of these--likely had a set of molecules that, by chance, could grow by polymerization. They could capture energy and nutrients from the environment and undergo polymerization. Furthermore, not only grow, but they can reproduce by some process. And right at the end of my talk, you're gonna hear about a way to produce long nucleic acid strands and get them to reproduce under simulated prebiotic conditions. So that's where I'm
So, here's what I claim. I claim that every time two of those come together, there's a chance for a water molecule to leave and produce what is called an ester bond. leave and stuff can polymerize.
As a super glue is very quickly reacting. It usually produces really short polymer chains that have a matrix with built in stress. Any time you have stress in a material, it's a potential failure point.
The glue sets quickly, but not fast enough to keep the whole stream connected. But with baking soda dissolved in the water, the super glue sets even faster. This creates a continuous length of polymer , which is really cool to see, but the resulting plastic is fragile and can easily be crushed. If you wanna glue things underwater with superglue, the key is actually to slow the polymerization down.
but long chains of glucose and a polymer and sort of as a polymer , it's bland.
And a lot of parts suffer from this problem called anisotropy, not the same in all directions. And so with our background in understanding polymers and polymer physics, we've focused on printing isotropically tough parts, and have found really neat ways to chemically cross-link plastics in this direction, as well as in this direction to make them strong and tough.
We were able to record 350-microvolt signals after 77 days, so almost three months in that rat brain, with these PEDOT electrodes. A PEDOT is a conductive polymer that we put, in this case, on top of our gold electrodes. Then what we did is we stained, we sectioned the rat brain and stained it for different cell types.
This whole thing is encapsulated in a thin layer of silicone. We've got a lithium polymer 10-milliamp power battery on top, so we're able to inductively power this device at 13 megahertz from a cage that a rat would sit in. And then we use that battery to stimulate and to block nerves in the rat.
But the whole thing was made very inexpensively for $100. And then we interface it with our polymer electrodes. So that's maybe arguably the more expensive part here at the ends, where we've been able to photolithographically define complex geometries
The temperature sensors can measure a thousandth of a degree change in temperature, but over a four-degree temperature window. Now we can change the polymer . And in each four degrees, we can measure something with a thousandth of a degree accuracy.
And you build sulfur bridges between the polymer molecules.
I talked to a couple of polymer chemists, and we agreed that chances are you could make a defensible argument that in a vulcanized rubber
So this is the cellulose polymer , and like all simple polymers , it's repeating unit over and over again.
And which, you know, it's impervious to water and it's soft enough to stand on so your legs don't get tired and it has a sort of a little porous surface. It's not flat like metal or polymer and so when it's printed it has a sort of stippled texture that I find really beautiful and you can really identify linoleum from that look once you know what it is.
And nitrocellulose is made by taking cellulose polymers , say from cotton or wood pulp.
And the next morning, the leaves were falling off. You can take isoprene and polymerize it.