Edwin L. Aguirre
The 41-year-old plastics engineering associate professor is one of the University’s leading researchers on sustainability and renewable materials, having devoted more than decade of his career developing products and processes that minimize the use and generation of hazardous substances.
Nagarajan and his graduate students have won awards from the U.S. Environmental Protection Agency
(EPA) for their efforts. In 2011, the Toxics Use Reduction Institute (TURI) at UMass Lowell named him the University Research Champion of the Year. Last year, Nagarajan was appointed co-editor of the Journal of Renewable Materials.
Published by Scrivener Publishing, the new periodical features peer-reviewed original research from all over the world on monomers, polymers and additives obtained from renewable/bio-based resources. Its maiden issue came out in January.
Here are some examples of the various sustainability projects Nagarajan is involved with at UMass Lowell:
Environmentally Friendly Detergents
Surfactants are surface-active substances commonly found in laundry or dishwashing detergents. They help remove dirt, oil, grease, food and other organic compounds from clothes and dishes by making the dirt and oil dissolve more readily in water during washing.
Nagarajan is collaborating with Asst. Prof. Bridgette Budhlall
in Plastics Engineering and Prof. Daniel Sandman in Chemistry to develop a new class of “greener” surfactants
as a safe, biodegradable and completely bio-based alternative to toxic nonylphenolethoxylates (NPEs). Although effective as cleaning agents, NPEs can accumulate in the environment, posing a threat to both humans and aquatic life.
The team’s research, which was supported by a seed grant from TURI, focuses on using abundant, renewable feedstock — namely, polysaccharide derived from bio-based waste fruit peels (polygalacturonic acid, or PGA) and sea algae (alginic acid) — as starting materials for synthesizing surfactants.
“We use naturally occurring materials in aqueous/non-toxic solvents, carried out in accordance with the principles of ‘green chemistry,’” says Nagarajan. “Our surfactants exhibit cleaning efficiencies similar to those of NPEs.”
Biodegradable Plastic Film for Packaging
Packaging is one of the major uses of plastics, accounting for more than 30 percent of the market. Plastic food-packaging films often require high resistance to moisture and oxygen to maintain freshness of the food for extended periods. Unfortunately, the bulk of the plastics used for flexible packaging are not biodegradable and end up polluting the land and sea if not properly recycled.
Nagarajan, together with Prof. Aldo Crugnola and Prof. Emeritus Nick Schott
in Plastics Engineering and Raul Raudales of the Mesoamerica Institute, are developing a packaging solution that is bio-based, sustainable and economically viable. This involves coating the polymer film with combinations of biodegradable and bio-derived materials such as chitosan (from shells of crabs and shrimp), plant-derived fatty acids and nano clay to improve the film’s barrier properties. The coating process also uses environmentally friendly solvents (predominantly water).
“We envision this approach would provide a greener alternative to petroleum-derived non-biodegradable plastics used in commercial food packaging,” says Nagarajan.
Making Plastics Flame-Resistant
Plastic materials have become an indispensable part of modern life due to their versatility, durability and low cost. However, most of the commercially produced plastics are inherently flammable and require additives called flame retardants
(FR) to reduce the risk of fire accidents. FR materials are used extensively in military and firefighter gear as well as in upholstery, textiles, plastics and consumer electronic items. Several commonly used flame retardants contain polybrominated diphenyl ethers, or PBDEs, which are very toxic and can persist in the environment.
“We are developing environmentally benign, non-toxic, halogen-free flame retardants using polyphenols, which are synthesized using bioderived phenols such as cardanol,” explains Nagarajan. “Cardanol is one of the main components of cashew nut shell liquid, a waste product of cashew nut processing.”
His collaborators include Prof. Jayant Kumar
in Physics as well as Ramanathan Nagarajan (no relation to Ramaswamy Nagarajan) and Ravi Mosurkal in the U.S. Army’s Natick Soldier Research, Development and Engineering Center (NSRDEC).
Biocatalytic Synthesis of Conjugated Polymers
Since the time of their discovery, conjugated polymers have become a field of great scientific and technological importance. Their opto-electronic properties have led to the development of a variety of useful products, including LEDs, field-effect transistors, photovoltaic cells, chemical sensors and biosensors.
Traditionally, conjugated polymers have been synthesized using techniques that rely on harsh chemical reagents/solvents and oxidants in their preparation. Nagarajan is collaborating with Kumar and Sandman as well as Lynne Samuelson and Ferdinando Bruno from NSRDEC on using biocatalysts — enzymes and enzyme mimics — to prepare conjugated and electrically conducting polymers.
“We have used oxidoreductase enzymes derived from horseradish and soybean peroxidase to synthesize conjugated polymers such as polyaniline, polypyrrole and PEDOT,” says Ramaswamy Nagarajan. “Our polymers have shown electrical conductivities similar to those prepared using conventional chemical oxidants. The polymers were synthesized using predominantly aqueous solutions, avoiding toxic solvents and oxidants.”