POLYETHYLENE GLYCOL AND RELATED SURFACTANTS AS GREEN SOLVENTS FOR CHEMICAL SYNTHESIS
Traditional solvents in chemical synthesis are typically volatile, flammable and oftentimes toxic and harmful to the environment. One of the 12 Principles of Green Chemistry consequently concerns the replacement of traditional solvents with environmentally benign ones. One potential solvent that has been evaluated as “green solvent” is polyethylene glycol (PEG). Much less evaluated as green solvents are PEG related nonionic surfactants. As solvents, these may dissolve a wide variety of substances because of their amphiphilic structure. Just like PEG, they too are environmentally benign substances because they possess low vapor pressure, are biodegradable and with respect to toxicity, there are no concerns because they are already widely used in industrial and household products. As a proof of concept, we have been able to carry out a particular Diels-Alder reaction in these surfactant media.
Very excitingly, since 2015 there is an ongoing research collaboration with researchers at the Technical University in Darmstadt, Germany. Their expertise is in solid-state NMR spectroscopy as well as Molecular Dynamics (MD) simulations. They study systems of chemical confined porous solid materials, which are often used as catalyst support material due to their large surface areas. Interestingly, PEG is a glass former. When frozen glasses preserve the structure of the liquid state. Interestingly, even the PEG related surfactants that form at least in part crystalline structures surprisingly still display active molecular motions in the frozen state. Thus, we are using solid state NMR research combined with MD simulation to learn more about the liquid structure and dynamics of PEG and related surfactants in bulk and under confinement.
This collaborative research is continued support by German and US funding (current funding grant CHE2522157) and has brought about some important project outcomes. The findings show that low molar weight PEGs are quite robust solvents in so far that vendor source, exact composition and water impurities have all negligible impact how PEG behaves. Presently, the project moves on in three directions:
Obtaining a better understanding of the complex hydrogen bonding interactions present in PEGs by studying other model molecules related to PEG but simpler molecular structures.
Exploring the behavior of solutes of limited solubility in PEG.
Host-guest interactions of PEG and related molecules in mesoporous materials.
Broader Impacts:
The findings may not only be important for researchers using PEG as a chemical solvent, but also for researchers that use PEG as an ingredient in their samples. Examples include PEG in heat transfer fluid, in capture medium for sequestering gases, and as crowding agent to study medium effects on biological molecules. PEG is also often used as building block in larger molecules. The so-called PEGylated molecules could be drugs to make them more water soluble, ionic liquids, phase transfer catalyst and many more.
A total of 13 undergraduate students of diverse backgrounds were involved in the project so far, including travel to Germany to conduct research in collaboration labs, gaining valuable professional experiences as future graduate student researchers or employees.
Current Project External Funding:
National Science Foundation (NSF) Research at Undergraduate Institution (RUI) #2522157, “RUI: Understanding Polyethylene Glycol as a Chemical Solvent in Bulk and Under Confinement”, $392,759 for award period 08/01/2025 to 07/31/2028.
Deutsche Forschungsgemeinschaft second continuation proposal of “Characterization of the Properties and Phase Behavior of nonionic surfactants confined in mesoporous silica materials employing solid state NMR techniques,” Buntkowsky, G. (Principal), Hoffmann, M. M. (Co-Principal), Gutmann, T. (Co-Principal), 365,567.00 Euro (October 1, 2023 - September 30, 2026).
National Science Foundation (NSF) Research at Undergraduate Institution (RUI) #1953428, “RUI: Solvation in Bulk and Confined Polyethylene Glycol”, $116,201 for award period 05/15/2020 to 04/30/2023.
Deutsche Forschungsgemeinschaft continuation proposal of “Characterization of the Properties and Phase Behavior of nonionic surfactants confined in mesoporous silica materials employing solid state NMR techniques,” Buntkowsky, G. (Principal), Hoffmann, M. M. (Co-Principal), Gutmann, T. (Co-Principal), 358,045.00 Euro (April 1, 2019 - March 31, 2022).
Deutsche Forschungsgemeinschaft “Characterization of the Properties and Phase Behavior of nonionic surfactants confined in mesoporous silica materials employing solid state NMR techniques,” Buntkowsky, G. (Principal), Hoffmann, M. M. (Co-Principal), Gutmann, T. (Co-Principal), 257,000.00 Euro. (September 1, 2015 - August 31, 2018).
Deutsche Forschungsgemeinschaft “Antrag einer Gewährung einer Unterstützung zum Aufbau internationaler Kooperationen”, Gerd Buntkowsky, Markus M. Hoffmann, $2,800, July 15, 2014 – July 14, 2015.
Recognition
2014 Roland Fontaine Award for Faculty-Student Scholarship, SUNY Brockport.
2011 Chancellor’s Award for Excellence in Scholarship and Creative Activity, State University of New York.
SUNY Promising Inventor Award, received on November, 4, 2004 in Albany, NY.
“NMR and MD Simulations of Non-Ionic Surfactants, Buntkowsky, Gerd; Hoffmann Markus, Molecules, 2025, Vol. 30, 309 (26 pages), (3390/molecules30020309).
“Thermal Behavior of n-Octanol and Related Ether Alcohols”, Hoffmann, Markus M.; Gutmann, Torsten; Buntkowsky, Gerd, Journal of Chemical and Engineering Data, 2025, Vol. 70, 600-606, (10.1021/acs/jced.4c00525).
“Novel Heterogeneous Pd Catalysts for Cross‐Coupling Reactions in Biocompatible Media: Structural Insights from Solid‐State NMR Techniques”, Wissel, Till; Rösler, Lorenz; Brodrecht, Martin; Höfler, Mark V.; Herr, Kevin; de Oliveira, Marcos; Klimavicius, Vytautas; Ebert, Martin; Breitzke, Hergen; Hoffmann, Markus; Buntkowsky, Gerd; Gutmann, Torsten, ChemCatChem, 2024, Vol. 0, , e202401511, (10.1002/cctc.202401511).
“Densities, Viscosities, and Self-Diffusion Coefficients of Octan-1-ol and Related Ether-Alcohol”, Hoffmann, Markus M.; Gonzalez, Anthony A.; Huynh, Mandy T.; Miller Kashane K., Gutmann, Torsten; Buntkowsky, Gerd, Journal of Chemical and Engineering Data, 2024, Vol. 69, 2688-1699, (1021/acs.jced.4c00195).
Exploring Competitive CO2 and H2S absorption in Polyethylene Glycol PEG200 by Molecular Dynamics Simulation, Haghani, Hossein; Imran-Shukat, Muhammad; Apaiyakul, Rattanaporn; Sema, Teerawat; Mosaddeghi, Hamid; Hoffmann, Markus M., Journal of Solution Chemistry, 2024, Vol. 410, 125568 (11 pages), (10.1016/j.molliq.2024.125568).
“Molecular Dynamics Study of the Green Solvent Polyethylene Glycol with Water Impurities”, Hoffmann, Markus M.; Too, Matthew D.; Paddock, Nathaniel A.; Horstmann, Robin; Kloth, Sebastian; Vogel, Michael; Buntkowsky, Gerd, Molecules, 2024, Vol. 29(9), 2070 (22 pages), (3390/molecules29092070).
“Structure and Dynamics of Complex Guest Molecules in Confinement, Revealed by Solid-State NMR, Molecular Dynamics, and Calorimetry”, Haro Mares, Nadia B.; Döller, Sonja C.; Wissel, Till; Hoffmann, Markus M., Vogel, Michael; Buntkowsky, Gerd, Molecules, 2024, Vol. 29(7), 1669 (26 pages), https://doi.org/10.3390/molecules29071669.
“Influence of APTES-Decorated Mesoporous Silica on the Dynamics of Ethylene Glycol Molecules Insights from Variable Temperature 2H Solid-State NMR”, Haro-Mares, Nadia; Brodrecht, Martin; Wissel, Till; Döller, Sonja C..; M. Rösler, Lorenz; Breitzke, Hergen.; Hoffmann, Markus M.; Gutmann, Torsten; Buntkowsky, Gerd, Journal of Physical Chemistry C, 2023, Vol. 127, 19735-19746, https://doi.org/10.1021/acs.jpcc.3c03671.
“Direct and indirect DNP NMR uncovers the interplay of surfactants with their mesoporous host material” Döller, Sonja; Brodrecht, Martin; Gutmann, Torsten; Hoffmann, Markus; Buntkowsky, Gerd, Journal of Physical Chemistry C, 2023, Vol. 127, 12125-12134, https://doi.org/10.1021/acs.jpcc.3c01946
“Solute-Solvent Interactions of 2,2,6,6-Tetramethylpiperidinyloxyl and 5-Tert-butylisophthalic Acid in Polyethylene Glycol as Observed by Measurements of Density, Viscosity, and Self-Diffusion Coefficient”, Hoffmann, Markus M; Randall, Nathaniel P.; Apak, Miray H.; Paddock, Nathaniel,; Gutmann, Torsten; Buntkowsky, Gerd, Journal of Solution Chemistry, 2023, Vol. 52, 685-707, https://doi.org/10.1007/s10953-023-01265-4.
“On the Behavior of the Ethylene Glycol Components of Polydisperse Polyethylene Glycol PEG200”, Hoffmann, M.M.; Too, M.D.; Nathaniel A. Paddock, N.A. Robin Horstmann, R.; Kloth, S.; Vogel, M.; Buntkowsky, G., Journal of Physical Chemistry B, 2023, Vol. 127, 1178-1196, /doi.org/10.1021/acs.jpcb.2c06773.
“A case study on the influence of hydrophilicity on the signal enhancement by dynamic nuclear polarization“, Döller, Sonja C.; Gutmann, T.; Hoffmann, M.M., Buntkowsky, G., Solid State Nuclear Magnetic Resonance, 2022, Vol. 122, 101829 (8 pages), doi.org/1016/j.ssnmr.2022.101829.
“Densities, Viscosities and Self-Diffusion Coefficients of Several Polyethylene Glycols”, Hoffmann, M.M.; Kealy, J. D.; Gutmann, T.; Buntkowsky, G., Journal of Chemical and Engineering Data, 2022, Vol. 67, 88-103, 1021/acs.jced.1c00759.
“Solid-state NMR studies of non-ionic surfactants confined in mesoporous silica”, Buntkowsky, G.; Döller, Sonja; Haro-Mares, N.; Gutmann, T.; Hoffmann, M.M., Zeitschrift für Physikalische Chemie, 2022, Vol. 236(6-8), 939-960. org/10.1515/zpch-2021-3132.
“Polyethylene Glycol as a Green Chemical Solvent”, Hoffmann, M.M, Current Opinion in Colloid &Interface Science, 2022, Vol. 57, article number 101537 (16 pages), org/10.1016/j.cocis.2021.101537.
Invited Talk: “Towards a Molecular Level Understanding of Polyethylene Glycol as a Solvent”, World Summit and Expo on Polymers and Composite Materials, Rome, Italy, Nov. 16, 2024.
Invited Talk: “Establishing an Understanding of Polydisperse Polyethylene Glycol as a Green Solvent”, Markus M. Hoffmann, 5th Advanced Chemistry World Congress, Amsterdam, Netherlands, March 25-26, 2024 (hybrid conference).
Invited Talk: “Insights Into Hydrogen Bonding of Polydisperse Polyethylene Glycol from Molecular Dynamics Simulations, Markus M. Hoffmann, International Conference on Polymer Science and Engineering, San Francisco, Ca, Oct. 30-Nov.3, 2023 (hybrid conference).
Invited Talk: “Physicochemical Properties of Polyethylene Glycol, a Green Solvent, Markus M. Hoffmann, International Conference on Polymer Science and Engineering, Los Angeles, CA, Oct. 17-21, 2022 (hybrid conference).
Talk: “Densities, Viscosities and Self-Diffusion Coefficients of Polyethylene Glycol, a Green Solvent”, Markus M. Hoffmann, ACS Fall 2022 National Meeting – Sustainability in a Changing World, Chicago, IL, Aug. 21-25, 2022 (hybrid conference).
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