About

Professor Karen I. Winey's research focuses on connecting polymer microstructure to ion and proton conductivity. Her work includes studying polymer and nanoparticle diffusion in polymer nanocomposites and devices. She is involved in revolutionizing the understanding of ionomer morphologies and exploring polymer-to-polymer transformations aimed at reducing plastic waste.

Research topics

• Chemical physics
• Materials science
• Chemistry
• Composite material
• Chemical engineering
• Physical chemistry
• Polymer chemistry
• Nanotechnology
• Organic chemistry
• Physics
• Computational chemistry
• Thermodynamics
• Statistical physics

Selected publications

• Diffusion of Bottlebrush Polymer-Grafted Nanoparticles: The Role of Matrix Molecular Weight

  Macromolecules · 2026-01-12

  articleSenior authorCorresponding

  Nanoparticle diffusion in a polymer matrix is known to be sensitive to the surface chemistry and size of the nanoparticles, and this study explores the effect of grafted polymers on the nanoparticles. We report the diffusion coefficients of nanoparticles grafted with bottlebrush polymers in melts of linear polymers. These bottlebrush polymer-grafted nanoparticles (PGNs) are comprised of large silica NPs (radius 80 nm) grafted with various backbone degrees of polymerization and fixed polystyrene side chains (4.2 kDa) to give bottlebrush molecular weights of 80–388 kDa. The polymer matrix is polystyrene (100 or 425 kDa), and nanoparticle diffusion was studied at 170 °C. After annealing a trilayer sample, time-of-flight secondary ion mass spectrometry (ToF-SIMS) measured the cross-sectional PGN concentration profiles and extracted diffusion coefficients. The PGNs with high bottlebrush molecular weights relative to the matrix polymer display core–shell diffusion behavior, wherein the shell thickness is comparable to the grafted bottlebrush thickness. Surprisingly, when the bottlebrush molecular weight is smaller than the matrix polymer, the PGNs diffuse 10–100 times faster than predicted, which we attribute to a local decrease in viscosity associated with disentanglement of the matrix polymer near the large nanoparticles.

  PublisherDOI

• Environmental chambers for thin film characterization by grazing incidence x-ray scattering and broadband dielectric spectroscopy

  Review of Scientific Instruments · 2026-04-01 · 1 citations

  articleSenior author

  While x-ray scattering and broadband dielectric spectroscopy (BDS) experiments are routinely performed in vacuum and under controlled humidity on bulk samples, in situ measurements of thin films in non-aqueous solvent vapor environments introduce additional requirements. Two controlled environmental chambers for performing grazing incidence x-ray scattering and BDS address this critical need for studying thin films in either aqueous or organic atmospheres. Both chambers enable temperature-controlled measurements under ambient conditions, flowing gas or solvent vapor, or partial pressures generated by solvent reservoirs. In situ control of temperature is achieved by attaching to an external temperature controller. To facilitate grazing incidence small- and wide-angle x-ray scattering and x-ray reflectivity, the environmental chamber for grazing incidence x-ray scattering has exit angles of 2θ = 38° and 51° in the horizontal and vertical directions, respectively. Low x-ray attenuation (∼ 10%) is achieved by using Kapton windows, and the chamber is sealed to enable use in evacuated x-ray scattering systems such as the Xenocs Xeuss 2.0. The broadband dielectric spectroscopy environmental chamber measures dipole dynamics and ionic conductivities of materials on interdigitated electrodes. Cord grip feedthroughs eliminate additional capacitance from the sample chamber and make the environmental chamber broadly compatible with electrochemical impedance spectrometers. The utility of these chambers is demonstrated on three polymeric systems with various film thicknesses, morphologies, and solvents.

  PublisherDOI

• Domain Alignment and Solvent Swelling Impact Ion Transport in a Multiblock Copolymer Ionomer

  Chemistry of Materials · 2026-04-10

  articleOpen accessSenior authorCorresponding

  The addition of polar solvents is known to increase the ionic conductivity of ion-containing polymers toward relevant values. For nanostructured polymers, ionic conductivity can also be improved by aligning the nanostructures to eliminate discontinuities in conduction pathways associated with misorientations of the conducting domains, grain boundaries, and defects. Here, we report improvements in ion conductivity with both solvent swelling and alignment by studying thin films of a precise amphiphilic multiblock copolymer ionomer. Samples were characterized under saturated solvent vapor by grazing incidence X-ray scattering and broadband dielectric spectroscopy using interdigitated electrodes. The layered ionic assemblies remain parallel to the substrate upon swelling the polar sublayers with selective solvents (λ = 2-2.5 solvent molecules per sulfonate). Relative to isotropic and solvent-free bulk samples, the in-plane ionic conductivities increase significantly due to alignment and solvent swelling with propylene carbonate, γ-butyrolactone, dimethyl carbonate, or diglyme. Interestingly, the ionic conductivity of an isotropic bulk sample swollen with propylene carbonate (λ = 1) is ∼ 1.5 orders of magnitude greater than an aligned thin film swollen with propylene carbonate (λ = 2.4). This result suggests that grain boundaries and defects in bulk samples of this alternating multiblock copolymer are preferentially swollen with solvent, providing pathways for rapid ion transport, and indicates routes to further improve ionic conductivity in solvent-swollen nanostructured ionomers.

  PublisherDOI

• Anion transport and selectivity in ordered nanoporous polymers with 1 nm scale charged pores

  ChemRxiv · 2026-04-02

  articleOpen access

  Solvated ions of the same valency and charge exhibit minor differences in bulk transport but may display strong ion-specific effects in nanoscale environments. Investigating such effects is challenged by the heterogeneous nature of conventional nanostructured membranes, which can smear out underlying structure-property correlations. We use a combination of electrochemical impedance spectroscopy, two-dimensional infrared spectroscopy, NMR relaxometry, and molecular dynamics simulations to systematically investigate anion transport in nanoporous polymers with uniform charged 1 nm scale pores. The pores are water-containing channels formed by lyotropic self-assembly of positively charged amphiphilic monomers that are then crosslinked to produce a highly ordered nanoporous polymer. Across a series of monovalent anions, we observe strong correlations of activation energy and conductivity with hydration enthalpy – more strongly hydrated species have higher conductivity and lower activation energies. These effects originate from differences in pore-wall interactions and solvation shell behavior, with more weakly hydrated species showing larger departures from their bulk behavior in their water coordination and activation energy in the membrane. Our results indicate that pore confinement amplifies the impact of water contributions to ion motion. Specifically, the ability to maintain hydration shell waters and concomitantly, to avoid interactions with hydrophobic pore wall patches, leads to significant differences in transport, and to ion-specific trends that are unexpected in nanoporous materials. These results provide new insight into ion transport in highly confined and hydration-limited geometries and suggest a mechanism by which ion selectivity can be explicitly manipulated.

  PublisherOA PDFDOI

• Extraction, purification, and reuse of dyes from coloured polyester textiles

  Nature Sustainability · 2025-11-24 · 2 citations

  article
  PublisherDOI

• Water Dynamics of Superacid Aromatic Proton Exchange Membranes for Fuel Cell Applications

  Macromolecules · 2025-02-20 · 3 citations

  articleOpen accessCorresponding

  Proton exchange membranes (PEMs) with high conductivity are of critical importance for the development of fuel cells, electrolyzers, and other electrochemical technologies. In this research, poly(1,1,2,2-tetrafluoro-2-phenoxyethane-1-sulfonic acid) (PTPS) with an aromatic polymer main chain and a perfluorinated superacidic polymer side chain was synthesized. The water dynamics of PTPS were characterized across various length scales using a combination of Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) and compared with Nafion, a standard perfluorinated PEM, and sulfonated poly(ether sulfone) (SPES 40), an aromatic PEM without perfluorinated superacid side chains. The T1 and T2 relaxation times of water in the samples probed by NMR increase from SPES 40 to PTPS to Nafion, indicating that the local motion of the water molecules becomes faster. This trend corresponds well with the relative fraction of bulk-like water determined using FTIR. At larger length scales, the diffusion coefficient of water was characterized using pulsed-field gradient NMR (PFG-NMR). At a longer diffusion time (Δ = 100 ms), PTPS has a smaller diffusion coefficient compared with both Nafion and SPES 40, due to restricted diffusion, and this effect is also evident in the proton conductivity of the hydrated membranes. From this comparison, it is apparent that the aromatic backbone and side chain type greatly influence the water dynamics in PEMs at various length scales and the water dynamics significantly impact the bulk proton conductivity. These insights will lead to new designs for aromatic PEMs and help to identify bottlenecks in current materials.

  PublisherDOI

• Correlating Solvation Shell Dynamics and Ion Transport in Highly Ordered Nanoporous Polymers

  ChemRxiv · 2025-03-21

  preprintOpen access

  A molecular-level understanding of the role of hydration in ion transport is essential for developing the next generation of polymeric anion exchange membranes (AEMs). Structural heterogeneity of conventional membranes, complex ion-water and ion-membrane interactions, and overlapping timescales, significantly hamper progress toward a comprehensive understanding. In this work, we use RH-dependent 2DIR and, EIS along with MD simulation to investigate the role of hydration in ion transport in a highly-ordered synthetic AEM with structural uniformity. 2DIR reveals sub-diffusive ion hopping timescales, while EIS measurements yield ion conductivity and enthalpic and entropic barriers for ion transport. Comparing the sub-diffusive and diffusive ion motions suggests a structural transport mechanism dictates ion diffusion across all hydration levels. A nonlinear relationship between ion hopping time and ion conductivity indicates a deviation of ion motion from Nernst-Einstein (NE) behavior. Finally, we demonstrate that hydration primarily regulates ion hopping rates, through tuning ion-pair interactions, thus influencing the activation barrier for ion transport in extremely nanoconfined AEMs.

  PublisherOA PDFDOI

• The Effects of Morphology and Hydration on Anion Transport in Self-Assembled Nanoporous Membranes

  ACS Nano · 2025-01-09 · 9 citations

  article

  Ordered nanoporous polymer membranes offer opportunities for systematically probing the mechanisms of ion transport under confinement and for realizing useful materials for electrochemical devices. Here, we examine the impact of morphology and ion hydration on the transport of hydroxide and bromide anions in nanostructured polymer membranes with 1 nm scale pores. We use aqueous lyotropic self-assembly of an amphiphilic monomer, with a polymerizable surfactant to create direct hexagonal (HI) and gyroid mesophases. UV-induced cross-linking leads to the formation of nanoporous polymers with water continuous channels. The membranes are mechanically robust and chemically durable, resisting degradation during extended exposure to 1 M NaOH solutions. We use a combination of electrochemical impedance spectroscopy, pulsed-field gradient NMR spectroscopy, and molecular simulations to elucidate anion and water transport. The as-prepared hexagonal systems display higher conductivity and lower activation energies for both anions relative to the gyroid system. When compared at equivalent hydration, however, gyroid and hexagonal membranes show similar activation energies, with nearly identical conductivities at ambient temperatures. Both ionic conductivity and water diffusivity increase with increasing hydration. The water uptake as a function of relative humidity for the hexagonal and gyroid mesophases ultimately dictates the water diffusion and magnitude of the ionic conductivity, with the hexagonal system showing overall higher capacity for hydration and thus faster ion transport. The durability of these materials under aggressive alkaline conditions and their relatively high hydroxide ion conductivity suggest that these nanostructured polymers could be of interest as membranes for alkaline fuel cells.

  PublisherDOI

• Diffusion of Nanoparticle Catalysts in Bi-Polar Membranes at Elevated Temperatures

  ECS Meeting Abstracts · 2025-07-11

  articleSenior author

  Recent interest in hydrogen fuel cells motivates development of bipolar membranes (BPMs) as a method for electrochemical hydrogen generation. BPMs are ionic heterojunctions valuable for their ability to establish a pH gradient with a basic anode and an acidic cathode. Between the cation and anion exchange membranes (CEM & AEM), metal-oxide nanoparticles (NPs) facilitate the water dissociation reaction to generate the hydrogen gas. We focus on characterizing the morphology of BPMs. BPM performance depends on the details of the composition and thickness of the dissociation layer. We are studying under what fabrication and use conditions nanoparticles in this central layer migrate into the CEM or AEM membranes. We first investigated CEM / AEM interfaces without catalyst nanoparticles as produced using solvent processing. SEM and Time of Flight Secondary Mass Spectroscopy (ToF-SIMS) imaging revealed interdiffusion of SPEEK8 (CEM) and PiperION (AEM) when the junction is heated in the presence of DMF. The result is a trilayer structure of SPEEK8, SPEEK8 mixed with PiperION, and PiperION, wherein the mixed layer is ~ 15 µm thick. A similar trilayer sample was observed when SnO 2 nanoparticles were sprayed onto PiperION in a grid pattern prior to depositing SPEEK8 from DMF solvent followed by heating. Moreover, this fabrication method distributes the SnO 2 nanoparticles throughout the trilayer morphology rather than confining the catalyst to the mixed layer or a thin coating, as is typically assumed. Despite this unexpected nanoscale morphology, these BPM show good electrochemical and adhesive performance. To explore the fundamentals of nanoparticle diffusion within CEMs and AEMs, we constructed diffusion couples in which a polymer-nanoparticle composite is sandwiched between thick polymer films. In this study the polymer in the nanocomposite and the thick layers is Nafion and the nanoparticles are TiO 2 NPs (radii 5, 30 or 100 nm). Upon annealing in dry conditions, the nanoparticles diffuse from the nanocomposite into the thick layers and we measure in 3D the evolution of the concentration profile using ToF-SIMS. From integrated profiles, we extract the nanoparticle diffusion coefficient. After completing these measurements in the dry conditions, we’ll explore nanoparticle diffusion in hydrated samples.

  PublisherDOI

• Investigating Morphology and Diffusion in Simulations of Precise Anion-Conducting Polymers

  Macromolecules · 2025-09-04 · 4 citations

  articleCorresponding

  Using atomistic molecular dynamics simulations, we investigate the morphology and transport properties of a new class of polymers which are functionalized with quaternary ammonium groups for use as anion exchange membranes. The polymers are precision polyolefins with either a trimethylammonium (p5CNMe3) or a dimethyl-hexyl ammonium (p5CNMe2Hx) pendant group at every fifth carbon along a polyethylene backbone. Simulations are performed at hydration levels of 5, 10, 15, and 20 water molecules per ammonium group. The hydrated polymers form nanoscale, percolated hydrophilic domains (water channels) in the hydrophobic polymer matrix that become wider with increasing water content. Water and hydroxide anion diffusion coefficients also increase with increasing water content. The morphology of the water domains is similar in both polymers, while the diffusion coefficients are somewhat lower in p5CNMe2Hx at fixed water content. The diffusion coefficients in both polymers fall on the same curve as a function of the fractal dimension of the percolated water channels, which appears to be a useful scalar measure of the effects of the nanoscale morphology on water and hydroxide anion transport.

  PublisherDOI

Recent grants

• Material World Network: Dynamics in Polymer Nanocomposites Containing Hard, Soft and Mobile Nanoparticles

  NSF · $520k · 2012–2016

• Precise Acid Copolymers and Ionomers: Morphology, Dynamics and Mechanical Properties

  NSF · $518k · 2011–2015

• Materials World Network: Polymers Dynamics in the Presence of Nanoparticles

  NSF · $480k · 2009–2013

• Precise Copolymers and Ionomers: Conductivity in Layered and Percolated Morphologies and Mechanical Properties

  NSF · $580k · 2015–2020

• Conductivity in Nanostructured Precise Polymers

  NSF · $620k · 2019–2025

Frequent coauthors

• Russell J. Composto

  University of Pennsylvania

  110 shared

• Nigel Clarke

  University of Sheffield

  58 shared

• Kenneth B. Wagener

  University of Florida

  50 shared

• J. E. Fischer

  Cogent Biosciences (United States)

  42 shared

• Yossef A. Elabd

  Texas A&M University

  41 shared

• Amalie L. Frischknecht

  39 shared

• Robert A. Riggleman

  University of Pennsylvania

  39 shared

• Daniel L. Polis

  35 shared

Education

• Ph.D., Chemical Engineering

  University of California, Berkeley

  1994

• B.S., Chemical Engineering

  University of California, Berkeley

  1989

Awards & honors

• 2023 American Chemical Society, ACS Polymer Chemistry Award
• 2022 American Association for the Advancement of Science, Fe…
• 2022 American Chemical Society, POLY/PMSE Division, Plenary…
• 2021 POLY (Division of Polymer Chemistry) American Chemical…
• 2020 Am. Inst. of Chemical Engineering, Materials Engr. and…