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Sanat Kumar
September 27, 2024
Sanat Kumar, Columbia University
Mechanism of Micro and Nanoplastics Formation
Time 10:30 am
Location L2D2

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It is well-established that micro and nanoplastics (MNPLs) are released from polymers through environmentally triggered bond breaking. However, the mechanism by which this Å-level process leads to nm-𝜇m sized fragments is poorly enunciated. Through experimental studies on three distinct chemistries, we demonstrate that only polymers with a semicrystalline morphology produce MNPLs under quiescent conditions. In this morphology, comprised of alternate crystalline and amorphous domains, chain scission occurs faster in amorphous regions. Through theoretical arguments, we show that tie molecules and bridging entanglements (“connectors”), which provide structural integrity to the semicrystalline structure by connecting two adjacent crystals, are preferentially broken. We propose that the cleavage of a threshold amount of connectors (i.e., scission of as little as 1% of chain bonds), leads to the spontaneous release of MNPLs. 

The resulting fragments comprise highly polydisperse stacks of lamellae, with an individual lamella — tens of nanometers thick — being the building block. Degradation of the crystals occurs over much longer time scales, explaining the environmental persistence of MNPLs, even under non-quiescent conditions. Since ~70 % of polymers are semicrystalline, engineering connectors may represent an effective strategy to reduce MNPL release rates. 

Sanat Kumar received his B.S. degree in chemical engineering from the Indian Institute of Technology in Chennai in 1981, followed by a Sc.D. from MIT in 1987. After completing a postdoctoral fellowship at IBM Almaden, he served as a faculty member at Penn State University and Rensselaer Polytechnic Institute. In 2006, he joined the Chemical Engineering Department at Columbia University, where he served as department chair from 2010 to 2016. Kumar’s research encompasses a broad range of polymeric and complex fluid systems, with a current focus on recycling polymers and mitigating nanoplastics. His work has earned him numerous honors, including visiting distinguished professorships at various international universities and the Polymer Physics Prize from the American Physical Society.

About Elizabeth D. Rockwell

Elizabeth D. Rockwell

A fourth generation Houstonian, Mrs. Rockwell was an Executive Director, Private Client Division of CIBC Oppenheimer Corp. She was widely recognized as an expert in retirement, estate, investment, and tax planning. She was an early proponent of the Keogh and IRA plans, for which she has been nationally recognized.

In 1991, she qualified to be a member of the Million Dollar Round Table as well as the Texas Leaders Round Table. Since 1990 she had authored a monthly column for the Houston Chronicle.

Mrs. Rockwell served as President of the UH College of Business Administration Foundation Board, as a member of the Dean’s Advisory Board, and was an Executive Professor for the college. She also served as a member of the advisory board of the Health Law and Policy Institute and as a Trustee of the University of Houston System’s Foundation, as well as a member of the UH System’s Planned Giving Council.

Mrs. Rockwell served on the Board of Governors for the Houston Forum, and as a Board member of the American Red Cross, the Greater Houston Women’s Foundation, the University of Houston Alumni Organization, and the Greater Houston Preservation Alliance. She was a member of the River Oaks Business Women’s Exchange Club, the National Tax Sheltered Annuity Association, the Texas Association of College Teachers, and the Houston Association of Life Underwriters.

Among her numerous honors, she has received an Honorary Doctorate of Humane Letters from the University of Houston, the Distinguished Alumna Award from the Houston Alumni Organization and from the UH College of Business Administration. Throughout the years she has been recognized for her many achievements by the Education Foundation of Harris County, the Houston Community College System’s Television Station Advisory Council, and the Houston Mayor’s READ Commission.

The Houston Alumni Center is home to the Elizabeth D. Rockwell President’s Suite. In September 1997, the Elizabeth D. Rockwell Career Services Center was opened in the UH College of Business Administration. She endowed the Chair for the Dean of the M.D. Anderson Library.

Mrs. Rockwell was listed in the Who’s Who in the South and Southwest; Who’s Who in finance and Industry; Who’s Who of American Women; and Who’s Who in the World.