About

Professor Tomasz Kowalewski leads a research group at Carnegie Mellon University that focuses on polymer-based functional materials and devices. His lab conducts highly interdisciplinary research centered on the design and synthesis of functional polymeric building blocks. A key aspect of their work involves methods to rearrange these building blocks over large areas through a technique called zone casting, enabling the fabrication of nano-devices. The research program encompasses several active areas including the nanoscale organization in thin films of regioregular poly(3-hexylthiophene) block copolymers and their applications in chemical sensors, the development and processing of long-range ordered block copolymer structures for nano-lithography, and the creation of a new class of nanostructured sp2 carbon systems for electronic materials. Additionally, the lab works on atomic force microscopy development and the study of high dielectric polymer materials for organic field effect transistors (OFETs). Professor Kowalewski's group is based in Room 527 of the Mellon Institute at Carnegie Mellon University in Pittsburgh, PA.

Research topics

• Chemistry
• Organic chemistry
• Polymer chemistry
• Composite material
• Chemical engineering
• Polymer science
• Materials science
• Combinatorial chemistry
• Photochemistry

Selected publications

• Examining the Impact of Side-Chain Chirality on Conformation of a Helical Poly(3-( <i>S</i> -1-ethylhexyl)esterfuran)

  Macromolecules · 2025-11-15

  articleOpen accessCorresponding

  A key challenge with synthetic chiral helical polymers is the precise determination of their structure, particularly their pitch and handedness. In past work, we demonstrated that poly(3-hexylesterfuran) (P3HEF) adopts a compact helical conformation (pitch ∼3.4 Å), driven by the syn conformational preference for regioregular, α-linked furan-3-carboxylates. Chiral side chains (either R or S) were attached to the furan monomer to synthesize poly(3-(1-ethylhexyl)esterfurans) (R- or S-P3(1EH)EF) with excess helix sense, but the branched alkyl group clearly impacted the folding behavior of these polymers. Here, through combined experimental and computational analyses, we assigned helix sense in these ester-functionalized polyfurans: where the S configuration for the side chain results in a left-handed helix bias, while the opposite R enantiomer results in a right-handed helix bias. While helix handedness can be biased by the attachment of the chiral side chain, the ethyl branch disrupts the formation of well-ordered helices when compared to the P3HEF analog. Solid-state characterization of S-P3(1EH)EF revealed isotropic grazing-incidence wide-angle X-ray scattering (GIWAXS) patterns, in contrast to the anisotropic edge-on orientation observed for P3HEF films. Thermal analysis with powder X-ray diffraction showed that while P3HEF remains stable up to 350 °C, the S-P3(1EH)EF melts near 150 °C in the solid state. Additionally, the chiral conformation of the S-P3(1EH)EF polymer is lost upon heating in THF solution above 30 °C, as evidenced by temperature-dependent circular dichroism (CD) studies. The results demonstrate that while the 1-ethylhexyl chiral side chains can bias helix sense, they also partially disrupt the formation and stability of a compact helical structure for ester-functionalized polyfurans.

  PublisherDOI

• Precise Synthesis of Ester-Functionalized Cyclo[6]- and Cyclo[7]furans

  The Journal of Organic Chemistry · 2025-07-07

  articleOpen accessCorresponding

  Shape-persistent conjugated macrocycles have attracted interest for their unique optoelectronic and self-assembly properties, but the syntheses to obtain these structures can be laborious. In this work, we describe the straightforward synthesis of a recently discovered class of macrocycle, the cyclo[n]furan, using Suzuki–Miyaura cross-coupling of a simple aromatic monomer. We demonstrate that the combination of hexyl 2-bromo-5-(boronic acid pinacol ester)furan-3-carboxylate with tris(dibenzylideneacetone)dipalladium(0), tri-tert-butylphosphonium tetrafluoroborate and cesium fluoride leads to cyclo[6]- and cyclo[7]furan esters in 45% yield (28% and 17%, respectively). Crude 1H NMR spectroscopy revealed that total conversion to macrocycles was 52 ± 6% over 3 runs, highlighting the robustness of this protocol for cyclofuran synthesis. The oligomerizations are rapid, and model compound studies suggest that a chain-growth mechanism may be operative. The hexyl-substituted cyclo[n]furan esters (n = 6 and 7) are separable via column chromatography. The unique optical and electronic features for each cycle can be partially explained by the size difference for the two systems, as well as the increased conformational flexibility for the larger, ester-functionalized cyclo[7]furan.

  PublisherDOI

• Heterogenous catalysis for oxygen tolerant photoredox atom transfer radical polymerization and small-molecule dehalogenation

  Polymer Chemistry · 2024-01-01 · 5 citations

  articleOpen access

  Heterogeneous photocatalysts (PCs) have garnered attention for their sustainability and cost-effectiveness.

  PublisherOA PDFDOI

• Comparing Ammonium and Tetraaminophosphonium Anion-Exchange Membranes Derived from Vinyl-Addition Polynorbornene Copolymers

  ACS Applied Energy Materials · 2024-02-13 · 15 citations

  articleOpen access

  for the ammonium and tetraaminophosphonium membrane electrode assemblies, respectively. The ammonium-based membrane was more water permeable as evidenced by water limiting current studies, which likely contributed to the improved performance.

  PublisherOA PDFDOI

• Hydrophilic Poly(meth)acrylates by Controlled Radical Branching Polymerization: Hyperbranching and Fragmentation

  Macromolecules · 2024-05-29 · 10 citations

  articleOpen access

  Topology significantly impacts polymer properties and applications. Hyperbranched polymers (HBPs) synthesized via atom transfer radical polymerization (ATRP) using inimers typically exhibit broad molecular weight distributions and limited control over branching. Alternatively, copolymerization of inibramers (IB), such as α-chloro/bromo acrylates with vinyl monomers, yields HBPs with precise and uniform branching. Herein, we described the synthesis of hydrophilic HB polyacrylates in water by copolymerizing a water-soluble IB, oligo(ethylene oxide) methyl ether 2-bromoacrylate (OEOBA), with various hydrophilic acrylate comonomers. Visible-light-mediated controlled radical branching polymerization (CRBP) with dual catalysis using eosin Y (EY) and copper complexes resulted in HBPs with various molecular weights (Mn = 38 000 to 170 000) and degrees of branching (2%–24%). Furthermore, the optimized conditions enabled the successful application of the OEOBA to synthesize linear-hyperbranched block copolymers and hyperbranched polymer protein hybrids (HB-PPH), demonstrating its potential to advance the synthesis of complex macromolecular architecture under environmentally benign conditions. Copolymerization of hydrophilic methacrylate monomer, oligo(ethylene oxide) methyl ether methacrylate (OEOMA500), and inibramer OEOBA was accompanied by fragmentation via β-carbon C–C bond scission and subsequent growth of polymer chains from the fragments. Furthermore, computational studies investigating the fragmentation depending on the IB and comonomer structure supported the experimental observations. This work expands the toolkit of water-soluble inibramers for CRBP and highlights the critical influence of the inibramer structure on reaction outcomes.

  PublisherDOI

• Modeling hyperbranched polymer formation via ATRP using dissipative particle dynamics

  Polymer · 2024-09-11 · 5 citations

  articleOpen access

  Hyperbranched polymers (HBPs) offer distinguishing, advantageous properties that arise from their distinctive complex topology. One of the effective approaches to the synthesis of hyperbranched structures involves the use of a branching initiator (inibramer) that is activated only after incorporation into a polymer chain. There remain, however, challenges in determining and characterizing the structures of the synthesized HBPs. Dissipative particle dynamics (DPD) was used to probe the effects of inibramer concentration, solvent concentration, and inibramer reactivity on the kinetics, molecular weight, and dispersity of HBPs. Additionally, DPD allows for direct observation of branched structures, which was not possible in previously reported Monte Carlo type simulations. It was found that higher inibramer concentrations led to faster monomer consumption while forming more dendritic structures with fewer defects. Additionally, high dispersities characteristic of HBP systems were found to originate from asymmetric propagation rates between inibramer-inibramer and inibramer-monomer reactions. • Modeling hyperbranched polymers (HBP) using DPD simulations via ATRP. • Effects of inibramer/solvent concentration, and inibramer reactivity were studied. • HBPs with high D is due to asymmetry in inibramer-mediated propagation rates. • R g of the HBPs exhibits power-law dependence with DP n . • Topology of individual macromolecules were characterized using dendrogram.

  PublisherDOI

• Solvent-driven helix-coil transitions in chiral conjugated polymers

  2024-09-30

  articleSenior author

  Helical conjugated polymers are of great interest for their potential as sources of circularly polarized luminescence for numerous electro-optical device applications including display technologies. Due to their relatively strong absorption cross sections and high emissivity in the visible wavelength range, these materials permit a detailed investigation of how the transition between helical and random coil forms are driven by polymer structural features such as chain length and chemical defects as well as environmental properties such as solvent and temperature. Bulk methods such as circular dichroism, absorption, and fluorescence as well as single-particle microscopy is used to probe the helix-to-coil phase transition in a model chiral polyfuran and to determine whether the conformations favored in solution are retained in the solid state. In addition, the transient dynamics and the effects of chemical doping on the electronic properties of the helix and coiled forms are explored.

  PublisherDOI

• Modeling Hyperbranched Polymer Formation Via Atrp Using Dissipative Particle Dynamics

  SSRN Electronic Journal · 2024-01-01

  preprintOpen access
  PublisherDOI

• Tuning the Thermochemistry and Reactivity of a Series of Cu-Based 4H⁺/4e^– Electron-Coupled-Proton Buffers

  Inorganic Chemistry · 2024-05-09 · 5 citations

  articleOpen access

  Electron-coupled-proton buffers (ECPBs) store and deliver protons and electrons in a reversible fashion. We have recently reported an ECPB based on Cu and a redox-active ligand that promoted 4H+/4e– reversible transformations (J. Am. Chem. Soc. 2022, 144, 16905). Herein, we report a series of Cu-based ECPBs in which the ability of these to accept and/or donate H• equivalents can be tuned via ligand modification. The thermochemistry of the 4H+/4e– ECPB equilibrium was determined using open-circuit potential measurements. The reactivity of the ECPBs against proton-coupled electron transfer (PCET) reagents was also analyzed, and the results obtained were rationalized based on the thermochemical parameters. Experimental and computational analysis of the thermochemistry of the H+/e– transfers involved in the 4H+/4e– ECPB transformations found substantial differences between the stepwise (namely, BDFE1, BDFE2, BDFE3, and BDFE4) and average bond dissociation free energy values (BDFEavg.). Our analysis suggests that this “redox unleveling” is critical to promoting the disproportionation and ligand-exchange reactions involved in the 4H+/4e– ECPB equilibria. The difference in BDFEavg. within the series of Cu-based ECPBs was found to arise from a substantial change in the redox potential (E1/2) upon modification of the ligand scaffold, which is not fully compensated for by a change in the acidity/basicity (pKa), suggesting “thermochemical decompensation”.

  PublisherOA PDFDOI

• Design, Synthesis and Aromaticity of an Alternating Cyclo[4]Thiophene[4]Furan

  Chemistry - A European Journal · 2023-04-11 · 4 citations

  articleOpen access

  Abstract A new class of conjugated macrocycle, the cyclo[4]thiophene[4]furan hexyl ester (C4TE4FE), is reported. This cycle consists of alternating α‐linked thiophene‐3‐ester and furan‐3‐ester repeat units, and was prepared in a single step using Suzuki–Miyaura cross‐coupling of a 2‐(thiophen‐2‐yl)furan monomer. The ester side groups help promote a syn conformation of the heterocycles, which enables formation of the macrocycle. Cyclic voltammetry studies revealed that C4TE4FE could undergo multiple oxidations, so treatment with SbCl 5 resulted in formation of the [C4TE4FE] 2+ dication. Computational work, paired with 1 H NMR spectroscopy of the dication, revealed that the cycle becomes globally aromatic upon 2e − oxidation, as the annulene pathway along the outer ring becomes Hückel aromatic. The change in ring current for the cycle upon oxidation was clear from 1 H NMR spectroscopy, as the protons of the thiophene and furan rings shifted downfield by nearly 6 ppm. This work highlights the potential of sequence control in furan‐based macrocycles to tune electronic properties.

  PublisherOA PDFDOI

Recent grants

• NIRT: Nanostructured Carbons from Self-Assembled Block Copolymer Precursors: From Synthesis and Characterization to Devices

  NSF · $1.4M · 2003–2009

Frequent coauthors

• Krzysztof Matyjaszewski

  Carnegie Mellon University

  169 shared

• Chuanbing Tang

  University of South Carolina

  45 shared

• Michał Kruk

  City University of New York

  43 shared

• Richard D. McCullough

  US Forest Service

  38 shared

• Jeffrey Pyun

  University of Arizona

  36 shared

• Detlef‐M. Smilgies

  Cornell University

  29 shared

• Anna C. Balazs

  University of Pittsburgh

  28 shared

• Wei Wu

  Donghua University

  28 shared

Education

• Ph.D.

  Polish Academy of Sciences

  1988