Home > Press > Odd reaction creates a stir in the lab: Rice University researchers find using certain stir bars can create laboratory errors
Rice University chemists discovered that stir bars covered in PTFE, also known as Teflon, react with chemicals in an unexpected way during the modification of nanotubes through Billups-Birch reduction. The bars that start out (and usually stay) white turn black in the solution and alter the results. (Credit: Photo by Brandon Martin/Rice University) |
Abstract:
The stirrers that mix cream into your coffee probably don't make much difference to the drink. But in a chemistry lab, it turns out using the wrong stirrer can skew the science.
Video produced by Brandon Martin/Rice University
Rice University scientists have determined that stir bars made of PTFE, more commonly known as Teflon, can introduce errors into a standard lab reaction used to manipulate the properties of carbon or boron-nitride nanotubes.
Stir bars are pellet-like rods of ferromagnetic metal covered in PTFE that sit in the bottom of a beaker and are turned by a rotating magnetic field. They allow a solution to be mixed in a closed flask without manual stirring.
The Rice lab of Angel Martí published a paper in the American Chemical Society journal ACS Omega outlining what happens when PTFE stir bars are used to functionalize nanotubes through Billups-Birch reduction, a long-used reaction developed in part by Rice Professor Emeritus of Chemistry Edward Billups that frees electrons to bind with other atoms.
Reduction is often used to make nanotubes more amenable to functionalization, the process of customizing them for applications by adding molecules like proteins. That can be as simple as dispersing nanotubes in a chemical bath laden with the molecules you want to add. Billups-Birch is one such method, a one-step process used to functionalize nanotubes with a variety of molecules, according to the researchers.
When they used it to modify nanotubes of boron-nitride, the researchers were surprised to see their tubes turn gray, while the PTFE stir bars turned black. Standard thermogravimetric analysis, usually adequate to see evidence of functionalization, didn't see anything wrong – but the researchers did.
"Aside from that, we couldn't get consistent results," Martí said. "Sometimes we would get very high functionalization – or apparent functionalization – and sometimes we wouldn't. That was really strange."
They found the lithium in the ammonia-based solvent used in the Billups-Birch reaction was reacting with the white PTFE from the bars, turning them black.
"Because carbon nanotubes are black, it would be easy to believe that nanotubes were depositing on the bars throughout the reaction," Martí said. "But that's not what happens. We found that in Billups-Birch conditions, the PTFE reacts.
"Teflon doesn't generally react with anything," he said. "That's why it's used in stir bars, and in cookware. That's why it's also easy to overlook what we saw happening in the lab."
Martí said search of the literature turned up nothing about avoiding PTFE in Billups-Birch.
"That was odd, too," he said. "Maybe everybody else knows – but just in case we decided to explore the problem. That's why we decided to write a paper."
The researchers suspect the unexpected reaction with Teflon is creating radicals that reduce the efficiency of the reaction and that can attack the boron-nitride or carbon nanotubes. In the meantime, their quick solution to the problem is perhaps the simplest.
"Now we use glass-coated stir bars," Martí said. "Glass is completely inert. That gives us reproducibility and good functionalization."
Rice graduate student Carlos de los Reyes is lead author of the paper. Co-authors are Rice graduate student Ashleigh Smith McWilliams, research assistant Kendahl Walz-Mitra, undergraduate students Katharyn Hernandez and Selin Ergülin, and Matteo Pasquali, the A.J. Hartsook Professor of Chemical and Biomolecular Engineering and a professor of materials science and nanoengineering and of chemistry. Martí is an associate professor of chemistry, of bioengineering and of materials science and nanoengineering.
The National Science Foundation, the Air Force Office of Scientific Research and the Welch Foundation supported the research.
####
About Rice University
Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation’s top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,962 undergraduates and 3,027 graduate students, Rice’s undergraduate student-to-faculty ratio is just under 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for lots of race/class interaction and No. 2 for quality of life by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger’s Personal Finance.
Follow Rice News and Media Relations via Twitter @RiceUNews.
For more information, please click here
Contacts:
Jeff Falk
713-348-6775
Mike Williams
713-348-6728
Copyright © Rice University
If you have a comment, please Contact us.Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.
Related Links |
New nano building block takes a bow:
Wiess School of Natural Sciences:
Related News Press |
News and information
Researchers develop artificial building blocks of life March 8th, 2024
Videos/Movies
New X-ray imaging technique to study the transient phases of quantum materials December 29th, 2022
Solvent study solves solar cell durability puzzle: Rice-led project could make perovskite cells ready for prime time September 23rd, 2022
Scientists prepare for the world’s smallest race: Nanocar Race II March 18th, 2022
Visualizing the invisible: New fluorescent DNA label reveals nanoscopic cancer features March 4th, 2022
Govt.-Legislation/Regulation/Funding/Policy
What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024
Researchers’ approach may protect quantum computers from attacks March 8th, 2024
Optically trapped quantum droplets of light can bind together to form macroscopic complexes March 8th, 2024
Possible Futures
Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024
Nanotubes/Buckyballs/Fullerenes/Nanorods/Nanostrings
Tests find no free-standing nanotubes released from tire tread wear September 8th, 2023
Detection of bacteria and viruses with fluorescent nanotubes July 21st, 2023
Discoveries
What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024
Researchers’ approach may protect quantum computers from attacks March 8th, 2024
High-tech 'paint' could spare patients repeated surgeries March 8th, 2024
Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024
Announcements
What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024
Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024
Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers/Posters
Researchers develop artificial building blocks of life March 8th, 2024
Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024
Military
What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024
New chip opens door to AI computing at light speed February 16th, 2024
NRL discovers two-dimensional waveguides February 16th, 2024
Grants/Sponsored Research/Awards/Scholarships/Gifts/Contests/Honors/Records
'Sudden death' of quantum fluctuations defies current theories of superconductivity: Study challenges the conventional wisdom of superconducting quantum transitions January 12th, 2024
The latest news from around the world, FREE | ||
Premium Products | ||
Only the news you want to read!
Learn More |
||
Full-service, expert consulting
Learn More |
||