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September 26, 2016

Poly6: Citrus Peels off a Performance Plastics Startup

Poly6’s Citrene™ a polymer material made from citrus peels, is a superior alternative to specialty composites, and is both biodegradable and energy efficient to produce.

Eric Brown

Like other tech startups, Boston-based Poly6 Technologies faces immense challenges as it strives for success. Yet Poly6 has several advantages, starting with a killer elevator pitch. Its flagship product -- Citrene™ -- is a high performing polymer material made from citrus peels. Citrene™ is marketed as a superior alternative to specialty composites and plastics used in high-value markets while also being biodegradable and far more energy efficient to produce.

Keith Hearon
Citrene™, which is initially targeted at the 3D printing resin and high-end wood coatings markets, is the first of many products based on biological sources that Poly6 hopes to produce in the coming years. “We take an oil that occurs naturally in the peels of lemons, oranges, and other citrus sources and convert it into a high-performance material,” says Keith Hearon, co-founder and CEO of Poly6 Technologies. “If you’ve ever dropped your cellphone and watched it shatter or looked on in horror as a beautiful hardwood floor is scratched, you realize there’s clearly a need for higher performing materials.”

The promise of the technology – and the company behind it – have been real enough to attract the attention of MIT’s Industrial Liaison Program (ILP), which has chosen Poly6 as one of the first six startups in the new MIT Startup Exchange STEX25 program. This more exclusive, and intensive, spinoff of MIT Startup Exchange aims to facilitate industry interaction with a more select group of the most innovative MIT-based startups. STEX25’s goal is to offer the 25 startups strategic advice, connections, and potential customers while simultaneously offering industry participants investment opportunities and early access to cutting edge technologies.

A Citrus-inspired Invention
Hearon invented the recipe for Citrene™ in 2012 when he was a Ph.D. student in Biomedical Engineering at Texas A&M University, and patented it before coming to MIT as a postdoc in 2014. Creating renewably sourced performance polymers was not his initial primary goal, however.

“I invented Citrene™ during an effort to recycle Styrofoam,” explains Hearon. “I learned that in the 1990s a Japanese company had used D-limonene, an oil that occurs naturally in citrus peels, to dissolve Styrofoam. It was only when I saw the chemical structure of D-limonene that my vision for creating Citrene™ arose.”

Hearon realized that Citrene™, which combines D-limonene with additional feedstocks, could emerge as a highly versatile, uniquely qualified class of polymers. At MIT Hearon focused on investigating Citrene’s™ use in specialized biomedical engineering applications.

“During my two years in MIT’s Langer Lab, we investigated applications ranging from wound healing to tissue regeneration,” says Hearon. “Being a part of Professor Bob Langer’s group at MIT was catalytic in inspiring me to pursue a new venture full time.”

With growing concerns about CO2 emissions and material waste, the eco-friendly Citrene™ has a number of advantages. “We project it takes up to 95 percent less energy to produce Citrene™ in comparison with competitive performance polymers,” says Hearon.

About 99 percent of plastics are made from petroleum, and over 590 billion pounds of non-degradable polymers are discarded each year, he notes. Polymer production also represents a big chunk of the over 23 percent of worldwide greenhouse gas emissions pegged to materials production.

“Our lower energy of production is associated with the simplicity of our manufacturing process, which also requires far less water than typical polymers and results in zero production waste.” He also notes that Citrene’s™ lack of toxicity affords greater safety both in manufacturing and usage, and its biodegradable bonds degrade in a tunable manner.

Yet, Hearon doesn’t like to call Citrene™ a “green material,” and he prefers talking more about the material’s toughness, durability and flexibility than its environmental benefits. “Citrene™ can be as tough as polycarbonate or as stretchy and flexible as a rubber band,” he notes. Citrene™-based resins offer unique low viscosity/high toughness combinations and excellent sunlight stability, he adds. In addition, Citrene™ coatings are more water resistant than many analog polymer coatings like polyurethanes and acrylics.

Poly6’s reluctance to push a green marketing angle stems in part from the fact that bioplastics tend to play to the low end of the polymers market. There’s an untested bias in the industry that high-performance polymers require petroleum derived feedstocks.

“We usually don’t compare Citrene™ with other bioplastics,” says Hearon. “Our real comparison is with other high performance materials. It just so happens that we’ve chosen environmentally beneficial starting points for building these materials. We do not consider ourselves an environmental play, although our long-term mission is one of positive environmental impact.”

Citrene’s™ customizable, on demand processing capabilities add to its material value proposition. “Citrene™ is sold as a portfolio of liquid resin products that harden in the presence of light, heating or other stimuli. “Hardening times are controllable from fractions of a second to 72 hours or longer and are easily customized to meet customers’ processing requirements,” says Hearon.

Poly6’s line of Citrene™ UV curable resins, which harden instantly after UV exposure, provide tougher, more versatile, less toxic and less oxygen inhibited alternatives to resins currently used in many 3D printing and high throughput UV coatings processes, says Hearon. He adds that Citrene™ thermally curable resins, which cure in durations ranging from seconds to hours, “offer tougher, less yellowing, less toxic and better surface wetting alternatives to resins used in composite production and specialized advanced manufacturing processes.”

Keeping Focused
Citrene’s™ initial traction has been strongest in the 3D printing/additive manufacturing industry, which will begin to use Citrene™ by the end of 2016. Poly6’s next targeted application is as a performance coating for wood products in home décor and marine applications. The first Citrene™ coatings products should arrive by mid-2017.

Going forward, a wider range of applications beckons. “Citrene™ has applications ranging from medical products to nail polish to specialty electronics,” says Hearon. “As an early-stage startup, focus is of utmost importance for Poly6, but we will eventually expand to other industries.”

Poly6 is developing a wide range of chemical formulations that it uses to optimize resins. “Our patents cover materials made from over 160 natural precursors ranging from citrus to pine to grape-skin extracts,” says Hearon. “Poly6’s products will be high value. We’re not trying to compete with commodity materials right now.”

MIT: A Guide on the Side from VMS to STEX25
Poly6 has more business experience than many engineering-based startups. Hearon previously worked part time for a medical device startup, and Matthew Stellmaker, Poly6’s co-founder & COO, founded a materials-related design-build firm in South America. Yet, Hearon and Stellmaker discovered that building a materials startup with cutting-edge technology from the ground up requires some new skills in the entrepreneurial toolbox. Fortunately, MIT’s many entrepreneurial support programs were there to help take Poly6 to the next level.

“At MIT I was able to engage in remarkable mentoring opportunities through the MIT Venture Mentoring Service (VMS) program, and Poly6 has also made invaluable industry connections through MIT’s Startup Exchange program,” says Hearon. “Now we are honored to be among the inaugural STEX25 class, through which we’re looking forward to even greater engagement with industry.”

When asked what advice he would give other tech startups, Hearon has this to say: “Persistence goes farther than intelligence. Without adherence to a single vision and mindset, it’s easy to lose confidence or direction.”

About MIT Startup Exchange, STEX25, and MIT’s Industrial Liaison Program (ILP)
MIT Startup Exchange actively promotes collaboration and partnerships between MIT-connected startups and industry. Qualified startups are those founded and/or led by MIT faculty, staff, or alumni, or are based on MIT-licensed technology. Industry participants are principally members of MIT’s Industrial Liaison Program (ILP).

MIT Startup Exchange maintains a propriety database of over 1,500 MIT-connected startups with roots across MIT departments, labs and centers; it hosts a robust schedule of startup workshops and showcases, and facilitates networking and introductions between startups and corporate executives.

STEX25 is a startup accelerator within MIT Startup Exchange, featuring 25 “industry ready” startups that have proven to be exceptional with early use cases, clients, demos, or partnerships, and are poised for significant growth. STEX25 startups receive promotion, travel, and advisory support, and are prioritized for meetings with ILP’s 230 member companies.

MIT Startup Exchange and ILP are integrated programs of MIT Corporate Relations.