chemistry hacks

612 Articles

New Shape-Shifting Polymer Works Hard, Plays Hard

February 16, 2016 by 22 Comments

A research group at the University of Rochester has developed a new polymer with some amazing traits. It can be stretched or manipulated into new shapes, and it will hold that shape until heat is applied. Shape-shifting polymers like this already exist, but this one is special: it can go back to its original shape when triggered by the heat of a human body. Oh, and it can also lift objects up to 1000 times its mass.

The group’s leader, chemical engineering professor [Mitch Anthamatten], is excited by the possibilities of this creation. When the material is stretched, strain is induced which deforms the chains and triggers crystallization. This crystallization is what makes it retain the new shape. Once heat is applied, the crystals are broken and the polymer returns to its original shape. These properties imply several biomedical applications like sutures and artificial skin. It could also be used for tailored-fit clothing or wearable technology.

The shape-shifting process creates elastic energy in the polymer, which means that it can do work while it springs back to normal. Careful application of molecular linkers made it possible for the group to dial in the so-called melting point at which the crystallization begins to break down. [Anthamatten] explains the special attributes of the material in one of the videos after the break. Another video shows examples of some of the work-related applications for the polymer—a stretched out strand can pull a toy truck up an incline or crush a dried seed pod.

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Eco Friendly Space-Fuel

February 14, 2016 by 64 Comments

If you’d like to risk blowing your fingers off for a good cause this week, look no further than [M. Bindhammer]’s search for an eco-friendly rocket fuel. [M. Bindhammer] predicts the increasing use of solid rocket boosters in the future. We’re into that. For now, rocket launches are so few and far between that the pollution doesn’t add up, but when we’re shipping consumer electronics to the moon and back twice a day, we might have a problem.

The most common solid rocket fuel emits chlorine gas into the atmosphere when burned. [Bindhammer] is exploring safe ways to manufacture a eutectically balanced and stabilized fuel compromised of sugar or sugar-alcohol, and potassium nitrate. If you watch home chemistry videos for fun on the weekend like us, [Bindhammer] goes through all his thinking, and even spells out the process for duplicating his fuel safely in a lab.

He’s done a lot of work. The resulting fuel is stable, can be liquid or solid. It has a high ignition temperature, but as you can see in the video after the break. Once ignited. It goes off like rocket fuel.

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Graphene Batteries Appear, Results Questionable

February 7, 2016 by 89 Comments

If you listen to the zeitgeist, graphene is the next big thing. It’s the end of the oil industry, the solution to global warming, will feed and clothe millions, cure disease, is the foundation of a space elevator that will allow humanity to venture forth into the galaxy. Graphene makes you more attractive, feel younger, and allows you to win friends and influence people. Needless to say, there’s a little bit of hype surrounding graphene.

With hype comes marketing, and with marketing comes products making dubious claims. The latest of which is graphene batteries from HobbyKing. According to the literature, these lithium polymer battery packs for RC planes and quadcopters, ‘utilize carbon in the battery structure to form a single layer of graphene… The graphene particles for a highly dense compound allowing electrons to flow with less resistance compared to traditional Lipoly battery technologies” These batteries also come packaged in black shrink tubing and have a black battery connector, making them look much cooler than their non-graphene equivalent. That alone will add at least 5mph to the top speed of any RC airplane.

For the last several years, one of the most interesting potential applications for graphene is energy storage. Graphene ultracapacitors are on the horizon, promising incredible charge densities and fast recharge times. Hopefully, in a decade or two, we might see electric cars powered not by traditional lithium batteries, but graphene supercapacitors. They’ll be able to recharge in minutes and drive further, allowing the world to transition away from a fossil fuel-based economy. World peace commences about two weeks after that happens.

No one expected graphene batteries to show up now, though, and especially not from a company whose biggest market is selling parts to people who build their own quadcopters. How do these batteries hold up? According to the first independent review, it’s a good battery, but the graphene is mostly on the label.

[rampman] on the RCgroups forums did a few tests on the first production runs of the battery, and they’re actually quite good. You can pull a lot of amps out of them, they last through a lot of charging cycles, and the packaging – important for something that will be in a crash – is very good. Are these batteries actually using graphene in their chemistry? That’s the unanswered question, isn’t it?

To be fair, the graphene batteries shipped out to reviewers before HobbyKing’s official launch do perform remarkably well. In the interest of fairness, though, these are most certainly not stock ‘graphene’ battery packs. The reviewers probably aren’t shills, but these battery packs are the best HobbyKing can produce, and not necessarily representative of what we can buy.

It’s also doubtful these batteries use a significant amount of graphene in their construction. According to the available research, graphene increases the power and energy density of batteries. The new graphene batteries store about as much energy as the nano-tech batteries that have been around for years, but weigh significantly more. This might be due to the different construction of the battery pack itself, but the graphene battery should be lighter and smaller, not 20 grams heavier and 5 mm thicker.

In the RC world, HobbyKing is known as being ‘good enough’. It’s not the best stuff you can get, but it is cheap. It’s the Wal-Mart of the RC world, and Wal-Mart isn’t introducing bleeding edge technologies that will purportedly save the planet. Is there real graphene in these batteries? We await an in-depth teardown, preferably with an electron microscope, with baited breath.

“You Sank My Dysprosium!”: Periodic Table Battleship

February 5, 2016 by 18 Comments

Kids these days, they have it so easy. Back in the old days, we learned our elements the hard way, by listening to “The Elements” by Tom Lehrer over and over until the vinyl wore out on the LP. Now, thanks to [Karyn], kids can learn the elements by playing “Battleship” – no tongue-twisting lyrics required.

For anyone familiar with the classic “Battleship” game, you’ll wonder why no one thought of this before. [Karyn]’s version of the game is decidedly low-tech, but gets the job done. She printed out four copies of the periodic table, added letters to label the rows, and laminated them. A pair of tables goes into a manila file folder, the tops get clipped together, and dry-erase markers are used to mark out blocks of two to five elements to represent the ships of the Elemental Navy on the lower table. Guesses at the location of the enemy ships can be made by row and series labels for the elementally challenged, or better yet by element name. Hits and misses are marked with Xs and Os on the upper table, and play proceeds until that carrier hiding in the Actinide Archipelago is finally destroyed.

This is pure genius in its simplicity and practicality, but of course there’s room for improvement. The action-packed video after the break reveals some structural problems with the file folders, so that’s an obvious version 2.0 upgrade. And you can easily see how this could be used for other tabular material – Multiplication Table Battleship? Sounds good to us. And if your nippers catch the chemistry bug from this, be sure to take a deeper dive into the structure of the periodic table with them.

Now, if you’ll excuse me: “There’s antimony, arsenic, aluminum, selenium, and hydrogen and oxygen and nitrogen and rhenium….”

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Cyborg Photosynthetic Bacteria!

January 19, 2016 by 4 Comments

This is weird science. Researchers at Lawrence Berkeley National Laboratory have taken some normal bacteria and made them photosynthetic by adding cadmium sulfide nanoparticles. Cadmium sulfide is what makes the garden-variety photoresistor work. That’s strange enough. But the bacteria did the heavy lifting — they coated themselves in the inorganic cadmium — which means that they can continue to grow and reproduce without much further intervention.

Bacteria are used as workhorses in a lot of chemical reactions these days, and everybody’s trying to teach them new tricks. But fooling them into taking on inorganic light absorbing materials and becoming photosynthetic is pretty cool. As far as we understand, the researchers found a chemical pathway into which the electrons produced by the CdS would fit, and the bacteria took care of the rest. They still make acetic acid, which is their normal behavior, but now they produce much more when exposed to light.

If you want to dig a little deeper, the paper just came out in Science magazine, but it’s behind a paywall. But with a little searching, one can often come up with the full version for free. (PDF).

Or if you’d rather make electricity, instead of acetic acid, from your bacteria be our guest. In place of CdS, however, you’ll need a fish. Biology is weird.

Headline images credit: Peidong Yang

Will Metallic Glue Replace Solder?

January 17, 2016 by 71 Comments

A video recently surfaced touting a new method of joining materials together. It’s called MesoGlue, and apparently, it could replace soldering or even welding in certain cases.

First announced on this month’s Advanced Materials and Processes (caution, big file!) it seems… legit. The basic premise is it uses nanorods of material — kind of like velcro — that once you push together, intertwine with each other, and become solid. They’re surrounded with a shell that liquefies, which solidifies the bond. This makes it able to withstand high heat, once bonded.

This kind of technology could have an impact in the way we join solder circuits, pipes, bond IC’s to heat sinks, and attaching de-similar materials with different thermal expansion coefficients.

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Conductive Silicone Makes Flexible Circuits

January 7, 2016 by 46 Comments

Flexible circuits and wearables seem to be all the rage these days. We’ve got conductive paint, glue, and even thread. So how about conductive silicone? Well, as it turns out — it’s not that hard to make.

[Andrew Quitmeyer] has been researching flexible circuits for a while now, and recently stumbled upon an expired patent for flexible ignition cables, using carbon fibers mixed with a conductive silicone. He started playing around with it, and discovered that by dissolving pieces of carbon fiber in rubbing alcohol, letting it dry, and then mixing it into a 2-part silicone you get pretty good electrical conductivity. In fact, in the range of 40-150ohms, which is actually pretty darn impressive!

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