Research Description:

Direct imaging of synthetic polymer membranes.

The development of materials for clean and efficient electrical energy utilization has been a longstanding goal. While significant progress has been made, none of the materials obtained thus far meet the specifications needed for operating a vehicle powered by a either a fuel cell or a battery alone. Softness is an essential characteristic of ion-conducting materials and the presence of water leads to softening of the hydrophilic domains, however, cross-over of reactants and products between the cathode and anode must be prevented. I therefore consider materials wherein soft ion-conducting channels are embedded in matrices that are designed to fulfill the required specifications.

My objective is to characterize the polymer in the hydrated state. While X-ray scattering experiments can be used to determine the average size and geometry of the channels in the presence of water, determining the true nature of the connectivity across different domains from scattering data is challenging. I will characterize the connectivity by electron tomography. The polymers will be soaked in water, vitrified by rapid cooling, and studied by electron tomography at cryogenic temperatures. By relating these microscopic measurements to transport measurements, I will establish the relationship between structure and function in these materials.

 Publications:

22. 1. M. J. Park, N. P. Balsara, “Phase Behavior of Symmetric Sulfonated Block Copolymers”. Macromolecules. ASAP, 2008.

21. M. J. Park, A. J. Nedoma, P. L. Geissler, A. Jackson, D. Cookson, N. P. Balsara, “Humidity-Induced Phase Transitions in Ion-Containing Block Copolymer Membranes”. Macromolecules. 41(6), 2271-2277, 2008.

20. M. J. Park, K. H. Downing,, A. Jackson, E. D. Gomez, A. M. Minor, D. Cookson, A. Z. Weber, N. P. Balsara, “Increased Water Retention in Polymer Electrolyte Membranes at Elevated Temperatures Assisted by Capillary Condensation”. Nano Lett. 7(11), 3547-3552, 2007.

19. M. Singh, O. Odusanya, G. M. Wilmes, H. B. Eitouni, E. D. Gomez, A. J. Patel, V. L. Chen, M. J. Park, P. Fragouli, H. Iatrou, N. Hadjichristidis, D. Cookson, N. P. Balsara, “Effect of Molecular Weight on the Mechanical and Electrical Properties of Block Copolymer Electrolytes”. Macromolecules. 40(13), 4578-4585, 2007.

18. N. P. Balsara, M. J. Park, “Block Copolymers and Nanotechnology”, J. Polym. Sci,: Part. B., 44(24), 3429-3430, 2006.

17. M. J. Park, J. Park, T. Hyeon, K. Char, “Effect of Casting Solvent on the Morphology of Poly(styrene-b-isoprene) Diblock Copolymer / Magnetic Nanoparticle Mixtures”, Langmiur, 38, 1375-1378, 2006.

16. M. J. Park, J. Park, T. Hyeon, K. Char, “Preferred Orientation and Epitaxial Morphological Transition of Block Copolymer Directed by Lattice-like Magnetic Nanoparticle Aggregates”, Adv. Mater., in revision.

15. M. J. Park, J. Kim, T. P. Lodge, K. Char, “Solid-like Transient Behavior at the Vicinity of Cylinder/Disorder Transition in Block Copolymer Solutions”, J. Phys. Chem. B., in press.

14. M. J. Park, Y. Kang, S. Kim, K. Char, “Selective Distribution of Interacting Magnetic Nanoparticles into Block Copolymer Matrices Using Facile Inversion of Micelle”, Nano Lett., submitted.

13. M. J. Park, T. P. Lodge, K. Char, “Order-Disorder Transition and Critical Micelle Temperature in Concentrated Block Copolymer Solutions”, Macromolecules 38, 2449-2459, 2005.

12. M. J. Park, J. Bang, T. P. Lodge, K. Char, “Interplay between Cubic and Hexagonal Cylinder Phases in Block Copolymer Solutions”, Langmuir 21, 1403-1411, 2005.

11. M. J. Park, J. Bang, T. Harada, T. P. Lodge, K. Char, “Epitaxial Transitions Among FCC, HCP, BCC, Cylinder Phases in a Block Copolymer Solution”, Macromolecules 37, 9064-9075, 2004.

10. J. Bang, K. Viswanathan, T. P. Lodge, M. J. Park, K. Char, “Temperature-Dependent Micellar Structures in Poly(styrene-b-isoprene) Diblock Copolymer Solutions Near the Critical Micelle Temperature” J. Chem. Phys. 121, 11489-11500, 2004.

9. T. P. Lodge, J. Bang, M. J. Park, K. Char, “Origin of the Thermoreversible fcc/bcc Transition in Block Copolymer Solutions”, Phys. Rev. Lett. 92(14), 145501-2, 2004.

8. M. J. Park, K. Char, “Effects of Block Copolymer Architecture and Composition on Micellization and Gelation: PEO-PLGA-PEO and PLGA-PEO-PLGA in Water”, Langmuir, submitted.

7. M. J. Park, K. Char, “Gelation of PEO-PLGA-PEO Triblock Copolymers Induced by Macroscopic Phase Separation”, Langmuir 20, 2456-2465, 2004.

6. M. J. Park, K. Char, “Effect of Shear Flow on the Polymeric Gels Formed by Macroscopic Phase Separation”, Macromol. Rapid Comm.25, 1082-1089, 2004.

5. B. Jeong, C. F. Jr. Windisch, M. J. Park, Y. S. Sohn, A. Gutowska, K. Char, “Phase Transition of the PLGA-g-PEG Copolymer Aqueous Solutions”, J. Phys. Chem. B. 107(37). 10032-10039, 2003.

4. M. J. Park, K. Char, “Two Gel States of a PEO-PPO-PEO Triblock Copolymer Formed by Different Mechanisms”, Macromol. Rapid Comm.23, 688-692, 2002.

3. M. J. Park, K. Char, “Phase Behavior of a PEO-PPO-PEO Triblock Copolymer in Aqueous Solutions: Two Gelation Mechanisms”, Macromol. Res.10, 325-331, 2002.

2. M. J. Park, K.-W. Kwon, H. Kim, Y. H. Bae, K. Char, “Gelation Behavior of PEO-PLGA-PEO Triblock Copolymers in Water”, Polymer 43, 3353-3358, 2002.

1. K.-W. Kwon, M. J. Park, J. Y. Hwang, K. Char, “Effect of Alcohol Addition on the Gelation in Aqueous Solutions of a Poly(ethyleneoxide)-Poly(propyleneoxide)-Poly(ethyleneoxide) Triblock Copolymer”, Polymer J. 33(5), 404-408, 2001.