About five years ago, independent chemist Ralph Locke and some fellow inventors were trying to help a beverage-container client figure out how to create a higher-density acrylic resin. They eventually achieved their aim – but also got a lot more than they bargained for.
In the process of that research, in one of those happenstance occasions in the laboratory, Locke and his team ended up finding a way to make plastics conductive to heat and electricity while sidestepping the usual compounding of conductive additives with a polymer in an extruder. The high temperatures and high pressures needed during such compounding often negatively impact the polymer’s properties.
“We stumbled into it – that’s an honest and good assessment,” said the Fort Myers, Fla.-based Locke, now chief development chemist of Mackinac Polymers LLC, in a Dec. 2 telephone interview.
To add density to the acrylic, the inventors decided to try adding bismuth salts. They wanted to find a way to insert the bismuth into the methacrylic acid polymer without adding it as a filler or “doping it,” Locke said, because the latter approach would not have led to a homogeneous blend of the ingredients.
“So I decided to try to react the bismuth in place, using bismuth chloride, and reacted it with the monomer itself. And as we were making the addition, we picked up that we were generating a tremendous amount of exotherm, or heat. We had started a reaction without polymerizing the methacrylic acid, and that reaction put the bismuth right into the polymer chain itself.”
“Locke said he’s had recent meetings with NASA. Researchers there were very knowledgeable about the science, expressed great interest, and came up ‘with a whole pile of applications for us to work with them on.'”
The result was indeed a higher-density acrylic that the client wanted, but Locke and his team realized there may be much more potential to this discovery. They thought that if it was possible to react a nano-sized particle of a transitional metal to the backbone, then perhaps it might be possible to put silver, gold, iron, or some other such metal particle on the backbone, and create something that was either stronger or conductive, or had capacitive properties.
And so in 2011 Locke started getting his funding together, established Mackinac Polymers (pronounced “Mackinaw,” after the island in northern Michigan), and began exploring these possibilities further. (He created Mackinac Polymers as the investment vehicle and holding company for the intellectual property that his previously existing entity called Mackinac Group manages and will commercialize.)
Locke and several other chemists and contributors then worked for the next several years to refine a synthesis process for integrating nanoparticles and graphene into various polymers. This summer they got their reward: The tiny, independent contract research company on July 7 was awarded U.S. Patent 9,074,053, titled “Polymeric Composition with Electroactive Characteristics.”
“We got all excited about it,” he said. “We can make it conduct electricity, and we can modulate the current or amplify the current with different salts.” The real trick to it, he explained, is the size and composition of the nanoparticles and where they are placed on the backbone. “The particles we’re using range between 30-50 nanometers.”
The typical method for making a polymer conductive is to “put a slug of carbon in it – usually 30 percent or more,” but the compounding process tends to degrade the polymer’s properties and the additives also are not homogeneous. “Normally, we need to add only 3-7 percent [of nanoparticles], based on the polymer weight – so we’re not talking about changing the polymer much.”
Mackinaw Group President Donald W. Phillips summarized the benefits of their process by saying, “It’s repeatable, it’s controllable, and it’s consistent, because it’s homogeneous.” That means, for example, that electricity can be conducted evenly across the entire length of, say, a large, flat panel made from such material.
Detroit-based Phillips – who previously worked during his 25-year career at foam products makers FXI and Foamex Corp., and at Advanced Materials Group and Petoskey Plastics Inc. – joined Mackinac in June to help commercialize this process.
He maintains that, even though the cost of the nanoparticle itself is typically more expensive than a competitive material such as carbon, the system cost when using the Mackinac process is likely to work out less expensive. This is because only a small amount of the nanoparticles is needed, and the costly, time-consuming compounding phase can be eliminated entirely.
Locke and Phillips see likely end-use applications in medical, aerospace and electronic devices and components, such as brand new capacitors or diodes that could include features not before possible with other metals or polymers. The researchers also are working on applications related to EMI shielding, thermal conduction, antistatic packaging film, and more. Antimicrobial medical uses are another possibility, since when silver is attached to the polymer backbone, it can kill bacteria on contact, while not leaching out from the polymer.
Locke said he’s had recent meetings with NASA. Researchers there were very knowledgeable about the science, expressed great interest, and came up “with a whole pile of applications for us to work with them on.”
The proof is in the poly urea…
Mackinaw Polymers scientists developed this poly urea pipe coating using their conductive plastics science. But how did they test it?
First, they sprayed alligator clips into the coating and connected them to an electricity meter. The strips were plugged into a wall socket and readings from the e-meter proved the material was conductive at 120v AC.
They left the material connected to the wall socket for a couple of hours. After it was unplugged, it held a 10v charge. When plugged back into the outlet, the material jumped back to 120v. The material was conductive and also functioned as a capacitor.
Additionally, the Mackinac process can yield transparent materials – in contrast to most of the current, traditionally compounded conductive materials, which tend to all be gray or black (because of the carbon). The Mackinac-created materials also can be processed using all the major plastics processes – injection molding, extrusion, blow molding, blown film, and the like. Due to the low loadings and fine particle sizes involved, such material also will be less abrasive on the processing machinery, according to Phillips.
Mackinac has done significant work so far on thermoset polymers such as polyurethanes and copolyesters, but they haven’t stopped there. Locke said his team has already “included nanoparticles on the backbones of polyolefins.” He further noted that other thermoplastics, such as polyamides, polyimides and other exotic TPs “are doable … because all we’re doing is including the reactive transition metal at the point of polymerization. So any polymer really is a candidate.“
Phillips said the firm’s approach to commercialization has shifted over time. “Our go-to-market strategy originally was to target the major chemical companies that had the ability to polymerize.” But, he noted, those companies tended to be more skeptical and dismissive, with a bit of a “not invented here” attitude. So Mackinac now is focusing more on specialty chemical houses and specialty applications, because those firms have specific needs that aren’t being filled, and this science, he asserts, can fill that need.
“We now have a manufacturing supply stream put together, with some partner companies, where we can actually supply resin or material, in whatever form you want it,” Phillips said. “We’re not quite to the point we can start shooting parts, and I don’t know that we would get to that level. But we definitely … can supply material for production.
“The next steps for us,” Phillips continued, “are to continue to get the word out about the science and its capability, and hopefully in the very near future, commercialize some of the science that we’re looking to co-develop with our partners.” Ideally, Mackinac is looking for three to six good development partners.
He said, “We have a couple of products that are done, and we’re in the licensing negotiation stage. I’m pretty optimistic that we should be able to have something done in 2016.”
Phillips summarized Mackinac’s approach like this: “We work with our partners. We co-develop – whether we black-box it, or whether we just consult and do it in their lab – but then when it’s done under the license agreement, we allow them to patent that part in their market in their application. All we want to do is license and commercialize the science. Our only patent is the technology.”
EDITOR’S NOTE: This is the first of two stories looking at the very different approaches that two firms are taking when it comes to developing electrically conductive plastics.
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Definately milestone in modern time inventions. I am sure new application would emerge consuidering this invention.
Hi, would like to be able to get in touch with the company, as wanted to explore conductive application for high heat resin. Please advise
Good to see people are still getting their hands dirty and thinking outside the box for new developments. I see a lot of limitations to conductive polymers today and hope technologies like this can really expand the capabilities of what is possible today.
I have a application for conductive plastics but it needs to be chrome plated, any suggestions ?
Ronald – We would definitely be interested in speaking with you. Please feel free to contact me direct at my e-mail [email protected] or at our site http://www.mackinacpolymers.com
Thank you for your comment.
Bruce – Please feel free to contact me direct at [email protected] or visit our website at http://www.mackinacpolymers.com.
Thank you for your inquiry.
We are interested in making Master batches of conductive product. Right now we are selling conductive black master batch for poluolefins, and would like to try this new technology.
Hello Nate,
Have you had any news on Conductive Transparent material for PET?