Research in Polymers and Materials Science.
The Hogen-Esch group is focused on the synthesis of polymers using advanced methods in all areas of polymer synthesis aimed at the fabrication of new materials with potential in energy and other materials science fields. Applications include: fuel cell and ultrafiltration/reverse osmosis membranes and polymers reinforced with perfluorocarbon clusters. Current areas of interest include:
A. Non-thermodynamic self-assembled polymer blends with hydrophilic nano-sized channels.
These are made from polymer blends consisting of commercially available polyvinylidenefluoride (PVDF) that is mixed with a styrene sulfonate copolymer. Heating to crosslink the copolymer and rapid quenching in water followed by ion exchange with sulfuric acid transforms the blend into a nano-structured hyper-branched polystyrene sulfonic acid suspended in the PVDF matrix. This material offer interesting perspectives, including their use as fuel cells and water purification. The research here will be aimed at understanding this expanding this concept into similar meta-stable polymer composites. These will include a number of promising blends of elastomeric and glassy polymers that will make it possible to optimize properties such as polymers with enhanced toughness. Examples are blends of high volume polymers such as polystyrene and polyisoprene or polybutadiene elastomers.
B. Synthesis of blends polymers end-functionalized with perfluorocarbon (RF) groups for reverse osmosis and other applications.
We have shown that the presence of perfluorocarbon (C8F17) and longer end groups greatly enhances cohesive forces in synthetic polymers that show major increases in strength (elastic and loss moduli) and thermal stabilities. These studies are being carried out in collaboration with the Professor Nutt group (Dept. of Chemical Engineering and Materials Science). RF end -functionalized polymers also allow the formation of different polymers to be mixed at the molecular level, giving rise to nano-structured polymer blends. The properties of such unusual blends remain largely unexplored. An intriguing example incorporates a suitable hydrophobic polymer such as polyacrylic acid or poly(2-acrylamido- 2-methyl propane sulfonic acid are expected to show enhanced water permeation with potential as ultrafiltration or reverse osmosis membranes.
- Yurdacan, M., Franke, O. Hogen-Esch, T. E. “Nanoindentation of Films of Perfluorotridecyl, Perfluorodecyl, and Perfluoroheptyl End-Functionalized Polystyrene at the Micron Scale.” Macromol. Chem. Phys. 2016, 217, 1260–1269.
- Piunova, V. A.; Hogen-Esch, T. E. “Synthesis of telechelic perfluorocarbon functionalized polystyrene and polybutylmethacrylate and characterization of their blends”Polymer 2015, 69, 58-65.
- Ming Li. “Development Of Polystyrene Sulfonic Acid-Polyvinylidene Fluoride Blends For Direct Methanol Fuel Cells ” December 2014.
- Shen J, Piunova V.A, Nutt S, Hogen-Esch T.E. “Blends of Polystyrene and Poly butylmethacrylate Mediated by Perfluorocarbon End Groups,” Polymer, 2013, 54, (21) 5790–5800.
- Yurdacan, H.M.; Franke, O.; Nutt, S.; Hogen-Esch, T.E. “Mechanical Properties of Perfluoroalkyl End- or Pendent Functionalized Polystyrene by Nanoindentation Measurements”
Volume: 245 Meeting Abstract: PMSE Preprts. 2013, 447.
- Piunova, V.; Shen, J-G; Hogen-Esch, T. E. “Blends of Perfluorocarbon End- Functionalized and Telechelic Polystyrene/Poly (n-butylmethacrylate): Synthesis and Morphology Studies”. PMSE Preprs. ACS, 2012, 244 ,426.
- Shen J.; Hogen-Esch T.E. “Block Copolymer-Like Morphologies from the Self Assembly in Polymer Blends Mediated by Fluorophilic Interactions” J. Am. Chem. Soc. 2008, 130, 10866-10867.
- Shi F.; Ling J.; Lu J.; Han B.; Lu, L.; Hogen-Esch T.E. “Synthesis of Isotactic-Polystyrene in Hydrocarbons by t-BuLi Initiation in the Presence of Sodium Dodecylbenzenes ulfonate” Polymer 2012, 53, 94-105.
- Da J.; Hogen-Esch T. E. “Synthesis and Association of Poly(N,N-dimethylacrylamide) Copolymers with Perfluorocarbon Pendent Groups Connected Through Polyethylene-glycol Tethers”. J. Pol. Sci. A. ( Chem. Ed.) 2004, 42, 360.
- Shen, J.; Hogen-Esch, T. E. “Fluorocarbon Mediated Polymer Blends and Methods for Making Thereof ” US Patent 8236902, September 12th, 2012.
- Jingguo Shen “Perfluorocarbon Mediated Self-Assembly of Vinyl Polymers”. PhD Thesis University of Southern California, August 2009.