New this year, the ACS GCI Green Chemistry & Engineering Conference technical programming was organized into thematic tracks. Each track was able to be followed throughout the conference so as to provide a deeper understanding of the theme, which reflected an important component of green chemistry innovation. One theme this year was “New Chemical Feedstocks,” organized by Julie Zimmerman of Yale University, which was dedicated to major trends in the development of alternative sources to fossil fuel for chemicals and technologies.
The session that kicked off this theme, “Building new chemical platforms from biological systems,” was chaired and organized by Professor Richard Wool of University of Delaware. According to Wool, "One of the greenest approaches to making eco-friendly materials is to let the materials be grown under circumstances that remove CO2 from the air by photosynthesis powered by the sun with little additional energy cost to process and bring the materials to market." Aligning with this, the GC&E session was devoted to how various sustainable bio-feedstocks and polymers can be modified for the synthesis and processing of materials the world depends on every day.
Seven talks comprised the session, and it began with Robert Mathers, an Associate Professor of Chemistry at Pennsylvania State University, who presented his talk “Bio-renewable alternatives to petroleum-based polyesters using continuous flow.” With the goal of using design criteria that can maximize the degree of sustainability and the potential for commercialization of polyesters, Mathers is working with several approaches to achieve 80% biobased content, reduce waste, design for degradation, etc. and use continuous flow to streamline the process. He started by discussing the simple Fischer Esterification reaction (a useful reaction because it is reversible, thereby allowing for biodegradability), which he was able to demonstrate with citric acid and glycerol to start a polyester network (and only liberated water as a byproduct). Overall this 100% biobased, self-catalyzing reaction exhibited a low waste ratio, and degradability; Mathers went on to describe other reactions and additional steps his group has taken to utilize biobased oils as starting materials and new processes that can eliminate halogenated waste and organic solvents, and isomerize via continuous flow to produce polyesters.
Throughout the morning attendees were privy to a wide range of discussions—from the topic of upcycling raw materials streams into highly functional polymers (as presented by Rick Tabor, a Research Associate in Stepan Company’s Synthesis Group) to utilizing lignin, a waste stream from papermaking that is typically incinerated, as less toxic alternative to styrene (as presented by Kaleigh Reno, a graduate student in Wool’s group). Some talks dug into applied, drop-in solutions for industrially relevant needs. For example Meg Sobkowicz-Kline, an Assistant Professor of Plastics Engineering at University of Massachusetts-Lowell, presented her talk “High speed reactive extrusion processing for renewable polymer blends.”
Attempting to address various concerns surrounding plastics such as toxicity, petroleum-derived raw materials, and degradation, Sobkowicz-Kline’s lab seeks to understand how to reactively combine commercial bioplastics to improve properties and create further viable alternatives to traditional plastics. Currently they are working to blend two bioplastics, polyamide 11 (PA11) and poly(lactic acid) (PLA)—PA11, a thermoplastic from castor oil, could allow for extended use of PLA, which can be brittle and not perform well with hot foods. The interchange reactions they have achieved thus far can be done in conventional processing equipment using some traditional condensation chemistry metal catalysts (eventually working towards enzymatic catalysis); as they proceed with their research, they hope to soon create an industrially relevant, strengthened bioplastic.
Other presenters included Madhu Kaushik (a graduate student at McGill University) who presented on “Cellulose nanocrystals (CNCs) as supporters, reducers and chiral inducers;” Mark Schofield (an Associate Professor of Chemistry at Haverford College) who presented his talk “Chemical modification of sophorolipids for the synthesis of novel biomaterials;” and C. Stewart Slater (a Professor of Engineering at Rowan University) presented “Shear-enhanced membrane processes for efficient biomass concentration in the design of biorefineries.”
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