Michael Garrison, NAWCWD research chemist, loads a polymer sample for dynamic mechanical analysis. The technique allows researchers to measure the mechanical properties of polymers at different temperatures. (U.S. Navy photo by Scott Clarke)

Michael Garrison, NAWCWD research chemist, loads a polymer sample for dynamic mechanical analysis. The technique allows researchers to measure the mechanical properties of polymers at different temperatures. (U.S. Navy photo by Scott Clarke)

NAWCWD researchers develop safer BPA alternatives

If you’ve ever seen an advertisement for a BPA-free water bottle or heard from a friend that you shouldn’t microwave your food in a plastic container, you may have wondered what all the fuss is about. BPA or bisphenol A is a ubiquitous chemical that can be converted to polycarbonates, epoxy resins, and coatings used in construction, automotive applications, food packaging, electronics, optics, medical materials and even thermal receipt paper.

BPA is so prevalent in the environment that you can find significant quantities in the blood and urine of nearly 90% of the human population. Unfortunately, BPA is an endocrine disruptor, which means that it binds to human hormone receptors that normally accommodate estrogen, thyroid hormones, and androgens. The binding of BPA by these receptors has been linked to a number of negative health effects including cardiovascular disease, behavioral changes, reduced immune response, and even cancer. Companies have responded by introducing BPA replacements, but many of these alternatives are known to be cytotoxic, genotoxic, and endocrine disruptors.

Recently, a team of researchers including Dr. Ben Harvey, NAWCWD senior research chemist and team lead; Michael Garrison, NAWCWD research chemist; Perrin Storch, at the time a Naval Research Enterprise Internship Program participant; Dr. William Eck and Dr. Valerie Adams from the Army Public Health Command; and Dr. Pat Fedick, NAWCWD analytical research chemist, synthesized and characterized a series of polymers derived from bio-based bisphenols. These bisphenols can be produced from sustainable sources including trees, turpentine, and clove oil. In addition to their derivation from sustainable feedstocks, the bisphenols have unique structures that prevent them from binding to estrogen receptor sites. Studies conducted by the Army Public Health Command showed that several of these bio-based molecules have no estrogenic effects. This work was recently published in Green Chemistry, the premier sustainable chemistry journal of the Royal Society of Chemistry, as a cover article.

“The materials we’ve developed can be derived from sustainable sources including waste biomass and plant extracts,” said Dr. Ben Harvey. “The lack of estrogenic effects exhibited by the bisphenols suggests that the positive health impacts of this technology could be profound. Derivation of the bisphenols and derivative polymers from sustainable biomass sources will allow us to reduce net greenhouse gas emissions while simultaneously making less toxic materials.”

“BPA is a ‘workhorse’ chemical used as a precursor for the plastics industry, specifically, in food/beverage containers,” Garrison said. “However, BPA is currently derived from limited petroleum resources and has shown negative health effects in humans after leaching into our food and drink, which means we need to find alternative precursors that are sustainable and have low toxicity.”

In addition to synthesizing the bisphenols, NAWCWD researchers converted them into polycarbonates, a class of engineering thermoplastics, several of which exhibited comparable or even better dimensional stability at elevated temperatures than BPA-polycarbonate, suggesting that the new materials have applications as direct replacements for petroleum-derived plastics.

“The Navy uses a number of thermoplastics, thermosetting resins, and composite materials, and we are always looking for new materials with better characteristics to improve performance,” said Dr. Stephen Fallis, NAWCWD’s Chemistry Division head. “Improved performance can take many forms, from increased melting temperatures, resistance to burning, or better manufacturing and repair approaches.”

In this case, the team was seeking out new sustainable, bio-derived polymers that performed as well as or better than current materials produced from petroleum. As often happens when doing basic research, this work went down one path and another path was uncovered.

“The team was originally studying aerospace composite materials derived from bio-based bisphenols. Dr. Harvey made the connection between his work on these materials and how the same molecules could also be utilized to make plastic bottles and other consumer products that are safer for the general population,” Fallis added.

NAWCWD has patented many of the non-estrogenic bisphenols and various derivatives over the last several years. These patents are available for licensing through the Technology Transfer program.

The Navy Technology Transfer program seeks to expand the public benefit of federally funded research and development by working collaboratively with the private sector to assess and develop new applications for technologies originally developed with military purposes in mind. In many cases, companies are able to license these innovations to create commercial products.

“The recent work on bisphenols is a perfect example of Navy research that has the potential to serve public interests to a much greater extent than the military uses alone,” said Dylan Riley, NAWCWD’s director of Technology Transfer. “Addressing the health and environmental implications of the ubiquitous use of BPA-containing plastics is a high-priority goal for both public and private sectors.  It is clear that the industry is in need of additional options to fully address this issue, and I am confident that public-private partnership could be the answer.”

For information about technologies currently available for transition or licensing, please visit www.techlinkcenter.org.



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