Carnegie Mellon University

Tomasz Kowalewski

Tomasz Kowalewski

Professor, Chemistry

  • Mellon Institute 525
  • 412-268-5927

Education

1988 Ph.D., Polish Academy of Sciences, Poland

Research

Physical chemistry, atomic force microscopy, proximal probe techniques, organic electronics, nano-structured materials, nanographene, self-assembly of organic materials, characterization of nanostructures, device fabrication and characterization

Research Interests

The common theme of Kowalewski group research is the self-organization of macromolecules, with the emphasis on the role that it can play in new nanostructured materials. Our work is highly interdisciplinary, and spans the range from molecular design, synthesis, through structure-properties studies to fabrication and characterization of devices. Major long-term projects currently underway in the group include: novel nanostructured carbons ("porous nanographenes") derived from block copolymer precursors; structure-transport properties relationships in semiconducting polymers and organic photovoltaics, and nanostructured polymer networks. The group is also actively involved in the application and development of proximal probe techniques, especially atomic force microscopy (AFM), to structure-property studies of materials and to manipulation of matter at the nanoscale level.

Projects

Porous nanographenes for energy storage

This work relies on the use of macromolecular carbon precursors, which through the process of self-assembly and directed self-assembly organize into well-defined nanoscale morphologies.1-5 After their nanostructure is fixed through chemical crosslinking, these materials are converted into porous nanocarbons with morphology resembling that of the starting material. Control over the nanoscale morphology opens the way to control of electronic structure by restricting the spatial extent of nanographitic domains, and, what is of particular importance, assuring their edge-on orientation with respect to the pore walls, thus guaranteeing their accessibility. Such overall morphology makes these materials particularly suitable for energy storage, especially as electrodes for supercapacitors, where they show specific capacitances per unit area far exceeding those exhibited by conventional materials.

Conducting polymers and photovoltaics

Here our primary goal is to reach the better understanding of the impact of nanoscale morphology on charge separation and transport processes in regioregular poly(3-alkylthiophenes) (rr-P3ATs) and their derivatives and in organic photovoltaic blends. Using the combination of AFM and Grazing Incidence Small Angle X-ray Scattering (GISAXS) we demonstrated that charge carrier mobilities in rr-P3ATs are dictated by the extent of organization of fibrillar nanostructures formed by π-stacking of polymer chains.7-14 The ability of narrow polydispersity rrP3ATs synthesized in McCullough laboratory to form well-defined fibrillar structures enabled us to use GISAXS patterns to recognize another particularly important aspect of molecular and nanoscale organization of polythiophene–like polymers: their intrinsic molecular and nanoscale porosity. This aspect of organization is a direct consequence of constraints imposed on intermolecular packing of polymer chains by strong interactions between rigid polymer backbones and their polydispersity. Currently we are focusing on understanding its impact on charge transport in conducting polymers, and on morphology and performance of polymer-based photovoltaics.

Nanostructured polymer networks

In this area we are collaborating with Matyjaszewski's group on exploring the impact of controlled heterogeneity on the structure and dynamics of polymer network systems. Particular emphasis is made on Lower Critical Solution Temperature (LCST) hydrogels, which upon the increase of temperature undergo a transition from a fully swollen to collapsed state. By comparing materials prepared by conventional and controlled radical polymerization we have demonstrated the impact of network heterogeneity on the extent and rate of swelling/deswelling transitions.15 We have also shown that the rate of the transition can be significantly increased by incorporation of dangling chains and use of branched architectures.16 Another group of projects in this area includes "self-healing" systems based on stars and nanogels with mobile arms, endowed with functionalities allowing for reversible breaking of inter-particle bonds.17 In situ AFM methods developed in our lab make it possible to use the AFM probe to induce the mechanical damage to the sample surface and then to visualize the healing process.

Publications

Photoactivated Structurally Tailored and Engineered Macromolecular (STEM) gels as precursors for materials with spatially differentiated mechanical properties
Antoine Beziau, Andria Fortney, Liye Fu, Chiaki Nishiura, Haobo Wang, Julia Cuthbert, Eric Gottlieb, Anna C. Balazs, Tomasz Kowalewski, Krzysztof Matyjaszewski, Polymer, Volume 126, 2017, Pages 224-230, ISSN 0032-3861,

Combining ATRP and FRP Gels: Soft Gluing of Polymeric Materials for the Fabrication of Stackable Gels
Antoine Beziau, Rafael N. L. de Menezes, Santidan Biswas, Awaneesh Singh, Julia Cuthbert, Anna C. Balazs, Tomasz Kowalewski and Krzysztof Matyjaszewski, Polymers 2017, 9(6), 186; doi:10.3390/polym9060186

Benzo[1,2-b:4,5-b′]difuran and furan substituted diketopyrrolopyrrole alternating copolymer for organic photovoltaics with high fill factor  
Jia Du , Andria Fortney, Katherine E. Washington, Michael C. Biewer, Tomasz Kowalewski and Mihaela C. Stefan,  J. Mater. Chem. A, 2017, 5, 15591-15600 DOI: 10.1039/C7TA04618A

Mesoporous nitrogen-doped carbons from PAN-based molecular bottlebrushes
Rui Yuan, Maciej Kopeć, Guojun Xie, Eric Gottlieb, Jacob W. Mohin, Zongyu Wang, Melissa Lamson, Tomasz Kowalewski, Krzysztof Matyjaszewski, Polymer, Volume 126, 2017, Pages 352-359, ISSN 0032-3861

Conjugated Polymers with Repeated Sequences of Group 16 Heterocycles Synthesized through Catalyst-Transfer Polycondensation
Chia-Hua Tsai, Andria Fortney, Yunyan Qiu, Roberto R. Gil, David Yaron, Tomasz Kowalewski, and Kevin J. T. Noonan, J. Am. Chem. Soc., 2016, 138 (21), pp 6798–6804

Controlled Preparation of Well-Defined Mesoporous Carbon/Polymer Hybrids via Surface-Initiated ICAR ATRP with a High Dilution Strategy Assisted by Facile Polydopamine Chemistry
Yang Song, Gang Ye, Zongyu Wang, Maciej Kopeć, Guojun Xie, Rui Yuan, Jing Chen, Tomasz Kowalewski, Jianchen Wang, and Krzysztof Matyjaszewski, Macromolecules, 2016, 49 (23), pp 8943–8950

Atomic force microscopy combined with optical tweezers (AFM/OT)
F Pierini, K Zembrzycki, P Nakielski, S Pawłowska and T A Kowalewski, Published 4 January 2016 • © 2016 IOP Publishing Ltd Measurement Science and Technology, Volume 27, Number 2, 2016

Atom transfer versus catalyst transfer: Deviations from ideal Poisson behavior in controlled polymerizations
Weiss, E. D.; Jemison, R.; Noonan, K. J. T.; McCullough, R. D.; Kowalewski, T., Polymer 2015, 72, 226-237.

Catalyst-Transfer Polycondensation Using Pd-PEPPSI-IPr for High-Molecular-Weight Regioregular Poly(3-hexylthiophene)
Qiu, Y. Y.; Mohin, J.; Tsai, C. H.; Tristram-Nagle, S.; Gil, R. R.; Kowalewski, T.; Noonan, K. J. T., Stille, Macromolecular Rapid Communications 2015, 36, 840-844.

Evolution of high-temperature molecular relaxations in poly(2-(2- methoxyethoxy)ethyl methacrylate) upon network formation
Kozanecki, M.; Pastorczak, M.; Okrasa, L.; Ulanski, J.; Yoon, J. A.; Kowalewski, T.; Matyjaszewski, K.; Koynov, K., Colloid and Polymer Science 2015, 293, 1357-1367.

Copolymer-templated nitrogen-enriched nanocarbons as a low charge-transfer resistance and highly stable alternative to platinum cathodes in dye-sensitized solar cells
Ju, M. J.; Choi, I. T.; Zhong, M. J.; Lim, K.; Ko, J.; Mohin, J.; Lamson, M.; Kowalewski, T.; Matyjaszewski, K.; Kim, H. K., Journal of Materials Chemistry A 2015, 3, 4413-4419.

Ductility, toughness and strain recovery in self-healing dual cross-linked nanoparticle networks studied by computer simulations
Iyer, B. V. S.; Yashin, V. V.; Hamer, M. J.; Kowalewski, T.; Matyjaszewski, K.; Balazs, A. C., Progress in Polymer Science 2015, 40, 121-137.

Effects of Delocalized Charge Carriers in Organic Solar Cells: Predicting Nanoscale Device Performance from Morphology
Gagorik, A. G.; Mohin, J. W.; Kowalewski, T.; Hutchison, G. R., Advanced Functional Materials 2015, 25, 1996-2003.

Cooperative, Reversible Self-Assembly of Covalently Pre-Linked Proteins into Giant Fibrous Structures
Averick, S.; Karacsony, O.; Mohin, J.; Yong, X.; Moellers, N. M.; Woodman, B. F.; Zhu, W.; Mehl, R. A.; Balazs, A. C.; Kowalewski, T.; Matyjaszewski, K., Angew. Chem., Int. Ed. 2014, 53, 8050-8055.

Effects of Delocalized Charge Carriers in Organic Solar Cells: Predicting Nanoscale Device Performance from Morphology
Gagorik, A. G.; Mohin, J. W.; Kowalewski, T.; Hutchison, G. R., Advanced Functional Materials 2014, DOI: 10.1002/adfm.201402332 

Appointments

YearsPosition
July 2011 Professor, Carnegie Mellon University
2005–2011 Associate Professor of Chemistry, Carnegie Mellon University
2000–2005 Assistant Professor of Chemistry, Carnegie Mellon University
1994–2000 Research Assistant Professor, Washington University in St. Louis
1989–1994 Research Associate, Washington University in St. Louis
1989 Visiting Lecturer, Southern Illinois University
1984–1988 Research Associate, Center of Molecular and Macromolecular Studies, Polish Academy of Sciences, Poland
1986 Research Fellow, Institute of Research on Polymer Rheology and Technology, Italy
1982–1984 Research Assistant, Center of Molecular and Macromolecular Studies, Polish Academy of Sciences, Poland
1979–1981 Post-graduate student, Institute of Physics, Polish Academy of Sciences, Poland