Matthew W. Liberatore

Colorado School of Mines, Golden, Colorado, United States

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Publications (54)92.87 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Anion exchange membranes (AEM) are solid polymer electrolytes that facilitate ion transport in fuel cells. In this study, a polystyrene-b-poly(vinylbenzyl trimethylammonium) diblock copolymer was evaluated as potential AEM and compared with the equivalent homopolymer blend. The diblock had a 92% conversion of reactive sites with an IEC of 1.72 ± 0.05 mmol g−1, while the blend had a 43% conversion for an IEC of 0.80 ± 0.03 mmol g−1. At 50°C and 95% relative humidity, the chloride conductivity of the diblock was higher, 24–33 mS cm−1, compared with the blend, 1–6 mS cm−1. The diblock displayed phase separation on the length scale of 100 nm, while the blend displayed microphase separation (∼10 μm). Mechanical characterization of films from 40 to 90 microns thick found that elasticity and elongation decreased with the addition of cations to the films. At humidified conditions, water acted as a plasticizer to increase film elasticity and elongation. While the polystyrene-based diblock displayed sufficient ionic conductivity, the films' mechanical properties require improvement, i.e., greater elasticity and strength, before use in fuel cells. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41596.
    Journal of Applied Polymer Science 10/2015; · 1.40 Impact Factor
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    ABSTRACT: We demonstrate that the true hydroxide conductivity in an e-beam grafted poly(ethylene-co-tetrafluoroethylene) [ETFE] anion exchange membrane (AEM) is as high as 132 mS cm-1 at 90 °C and 95%RH, comparable to a proton exchange membrane, but with very much less water present in the film. To understand this behaviour we studied ion transport of hydroxide, carbonate, bicarbonate and chloride, as well as water uptake and distribution. Water uptake of the AEM in water vapor is an order of magnitude lower than when submerged in liquid water. In addition 19F pulse field gradient spin echo NMR indicates that there is little tortuosity in the ionic pathways through the film. A complete analysis of the IR spectrum of the AEM and the analyses of water absorption using FT-IR led to conclusion that the fluorinated backbone chains do not interact with water and that two types of water domains exist within the membrane. The reduction in conductivity was measured during exposure of the OH- form of the AEM to air at 95% RH and was seen to be much slower than the reaction of CO2 with OH- as the amount of water in the film determines it ionic conductivity and at relative wet RHs its re-organization is slow.
    Physical Chemistry Chemical Physics 12/2014; · 4.20 Impact Factor
  • T. P. Pandey, B. D. Peters, M. W. Liberatore
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    ABSTRACT: Understanding the role of water in anion exchange membrane (AEM) used in fuel cells is essential for commercial application.1 Many literatures published have emphasized the important of water to optimize membrane properties such as ionic conductivity, ion transport, and mechanical and chemical stability.1-3 Recently, the idea of using thin layers of catalyst and solubilized ionomer is very common and demands the greater understanding of hydration behavior of AEMs.4 Several techniques have been used to understand the diffusion of water in membranes. Elabd et al5 have summarized the diffusion coefficient values from different methods and mentioned the in-consistency among different methods. A time resolved Fourier transform infrared- attenuated total reflectance (FTIR-ATR) spectroscopy is a less common method to measure the water diffusion through AEMs although this method has been recently used in other materials.6, 7 FTIR-ATR spectra were collected using Nexus 4700 (Thermo-fisher) with an ATR accessory (Specac, Inc). A liquid nitrogen cooled mercury cadmium telluride (MCT) detector was used to collect a spectrum with 128 scans every 25 seconds with a resolution of 4 cm-1. A custom built design was used to control RH of the membrane sample during experiments. In order to verify the experimental setup, the diffusion coefficient of water through Nafion 117® membrane was observed at the same order of magnitude (1.63±0.27 x 10-7 cm2/s vs 3.71x 10-7 cm2/s observed by Elabd et al7) when the relative humidity of the sample was changed from 0 to 100 %RH. Water diffusion coefficient was then measured for AEMs as a function of temperature and RH. The Fickian water diffusion coefficient for AEMs was observed to be lower than proton exchange membranes by one order of magnitude. Figure 1 shows the comparison of water diffusion kinetics between one of the anion exchange membranes and Nafion 117® at 30 oC. In this work, water behavior of different AEMs as a function of temperature and RH will be presented, the energy barrier for the water diffusion through these membrane will be discussed and the science behind a slow water diffusion through AEMs will be explored. Figure 1. Time-resolved normalized absorbance for O-H stretching vibration collected using FTIR-ATR at 30oC when RH was increased from 0 to 100%. Acknowledgement The authors would like to thank the US Army Research Office for the funding under the MURI #W911NF-10-1-0520and the purchase of FTIR microscope from ARO DURIP #W911NFNF-0462 References * Merle, G.; Wessling, M.; Nijmeijer, K., Anion exchange membranes for alkaline fuel cells: A review. Journal of Membrane Science 2011, 377, 1-35. * Duan, Q. J.; Ge, S. H.; Wang, C. Y., Water uptake, ionic conductivity and swelling properties of anion-exchange membrane. Journal of Power Sources 2013, 243, 773-778. * Myles, T. D.; Kiss, A. M.; Grew, K. N.; Peracchio, A. A.; Nelson, G. J.; Chiu, W. K. S., Calculation of Water Diffusion Coefficients in an Anion Exchange Membrane Using a Water Permeation Technique. Journal of the Electrochemical Society 2011, 158, B790-B796. * Mehta, V.; Cooper, J. S., Review and analysis of PEM fuel cell design and manufacturing. Journal of Power Sources 2003, 114, 32-53. * Hallinan, D. T.; Elabd, Y. A., Diffusion of Water in Nafion Using Time-Resolved Fourier Transform Infrared−Attenuated Total Reflectance Spectroscopy. The Journal of Physical Chemistry B 2009, 113, 4257-4266. * Sundfors, F.; Lindfors, T.; Hofler, L.; Bereczki, R.; Gyurcsanyi, R. E., FTIR-ATR Study of Water Uptake and Diffusion through Ion-Selective Membranes Based on Poly(acrylates) and Silicone Rubber. Analytical Chemistry 2009, 81, 5925-5934. * Hallinan, D. T.; Elabd, Y. A., Diffusion and Sorption of Methanol and Water in Nafion Using Time-Resolved Fourier Transform Infrared−Attenuated Total Reflectance Spectroscopy. The Journal of Physical Chemistry B 2007, 111, 13221-13230.
    2014 ECS and SMEQ Joint International Meeting; 10/2014
  • Marc W. Donnelly, Mahilet Hailemichael, Matthew W. Liberatore
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    ABSTRACT: The concentration dependence of viscosity is examined for four cationically modified cellulose polymers (UCARE™ JR400, UCARE™ JR30M, UCARE™ LR400, and UCARE™ LR30M) in both salt-free and 50 mM NaCl solution. Similarities in the four polymer systems include: Newtonian viscosity in the dilute regime, shear thinning at higher concentrations, four concentration regimes in salt-free solution, and three concentration regimes in salt solution. The zero shear rate viscosity and the degree of shear thinning increase with increasing polymer concentration in both salt and salt-free solutions. While the addition of salt to the lower molecular weight polymers JR400 and LR400 resulted in small changes in viscosity across all concentrations, JR30M and LR30M exhibited significant decreases (up to 81%) and increases (up to 57%) in viscosity upon the addition of salt in the semidilute and entangled regimes, respectively. This viscosity increase in the entangled regime (when comparing salt-free and 50 mM NaCl solutions) is reported for the first time in cationically modified cellulose polymers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41616.
    Journal of Applied Polymer Science 10/2014; · 1.40 Impact Factor
  • Eric B. Webb, Carolyn A. Koh, Matthew W. Liberatore
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    ABSTRACT: Structure I methane hydrates are formed in situ from water-in-mineral oil emulsions in a high pressure rheometer cell. Viscosity is measured as hydrates form, grow, change under flow, and dissociate. Experiments are performed at varying water volume fraction in the original emulsion (0–0.40), temperature (0–6 °C), and initial pressure of methane (750–1500 psig). Hydrate slurries exhibit a sharp increase in viscosity upon hydrate formation, followed by complex behavior dictated by factors including continued hydrate formation, shear alignment, methane depletion/dissolution, aggregate formation, and capillary bridging. Hydrate slurries possess a yield stress and are shear-thinning fluids, which are described by the Cross model. Hydrate slurry viscosity and yield stress increased with increasing water volume fraction. As driving force for hydrate formation decreases (increasing temperature, decreasing pressure), hydrate slurry viscosity increases, suggesting that slower hydrate formation leads to larger and more porous aggregates. In total, addition of water to a methane saturated oil can cause more than a fifty-fold increase in viscosity if hydrates form.
    Industrial & Engineering Chemistry Research 04/2014; 53(17):6998–7007. · 2.24 Impact Factor
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    ABSTRACT: Block copolymers of polystyrene-b-poly(vinyl benzyl trimethylammonium tetrafluoroborate) (PS-b-[PVBTMA][BF4]) were synthesized by sequential monomer addition using atom transfer radical polymerization. Membranes of the block copolymers were prepared by drop casting from dimethylformamide. Initial evaluation of the microphase separation in these PS-b-[PVBTMA][BF4] materials via SAXS revealed the formation of spherical, cylindrical, and lamellar morphologies. Block copolymers of polystyrene-b-poly(vinyl benzyl trimethylammonium hydroxide) (PS-b-[PVBTMA][OH]) were prepared as polymeric alkaline anion exchange membranes materials by ion exchange from PS-b-[PVBTMA][BF4] with hydroxide in order to investigate the relationship between morphology and ionic conductivity. Studies of humidity [relative humidity (RH)]-dependent conductivity at 80 °C showed that the conductivity increases with increasing humidity. Moreover, the investigation of the temperature-dependent conductivity at RH = 50, 70, and 90% showed a significant effect of grain boundaries in the membranes against the formation of continuous conductive channels, which is an important requirement for achieving high ion conductivity. © 2012 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1751–1760, 2013
    Journal of Polymer Science Part B Polymer Physics 12/2013; 51(24):1751-1760. · 2.22 Impact Factor
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    ABSTRACT: An alkaline exchange membrane (AEM) based on an aminated trimethyl poly(phenylene) is studied in detail. This article reports hydroxide ion conductivity through an in situ method that allows for a more accurate measurement. The ionic conductivities of the membrane in bromide and carbonate forms at 90 °C and 95% RH are found to be 13 and 17 mS cm−1 respectively. When exchanged with hydroxide, conductivity improved to 86 mS cm−1 under the same experimental conditions. The effect of relative humidity on water uptake and the SAXS patterns of the AEM membranes were investigated. SAXS analysis revealed a rigid aromatic structure of the AEM membrane with no microphase separation. The synthesized AEM is shown to be mechanically stable as seen from the water uptake and SAXS studies. Diffusion NMR studies demonstrated a steady state long-range diffusion constant, D∞ of 9.8 × 10−6 cm2 s−1 after 50–100 ms. © 2012 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1743–1750, 2013
    Journal of Polymer Science Part B Polymer Physics 12/2013; 51(24):1743-1750. · 2.22 Impact Factor
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    ABSTRACT: In this study, new alkaline exchange membranes were prepared from the perfluorinated 3M ionomer with various quaternary ammonium cations attached with sulfonamide linkage. The degree of functionalization varied depending on the cation species, resulting in different ion exchange capacities (IECs), 0.33–0.72 meq g−1. There was evidence of polymer degradation when the films were exposed to hydroxide, and hence all membrane characterization was performed in the chloride form. Conductivity was dependent on cation species and IEC, Ea = 36–59 kJ mol−1. Diffusion of water through the membrane was relatively high 1.6 × 10−5 cm2 s−1 and indicated restriction over a range of diffusion times, 6–700 ms. Water uptake (WU) in the membranes was generally low and the hydration level varied based on cation species, λ = 6–11. Small-angle scattering experiments suggested ionic aggregation, 37–42 Å, independent of cation species but slight differences in long-range order with cation species. © 2012 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1761–1769, 2013
    Journal of Polymer Science Part B Polymer Physics 12/2013; 51(24):1761-1769. · 2.22 Impact Factor
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    ABSTRACT: During the chemical mechanical polishing (CMP) process, it is believed that shear thickening of the slurry, caused by particle agglomeration, has the potential to result in a significant increase in particle-induced surface defects (i.e, scratches, gouges, pits, etc.). In this study, we have developed a methodology for the synchronized measurement of rheological behavior while polishing a semiconductor wafer, the first of its kind (a technique termed rheo-polishing). We investigate the shear thickening of a 25 wt% fumed silica slurry with 0.15 M added KCl and its impact on polishing performance and subsequent surface damage. The thickened slurry displays a ∼5-fold increase in viscosity with increasing shear rate. As the shear rate is reduced back to zero, the slurry continues to thicken showing a final viscosity that is ∼100x greater than the initial viscosity. Optical microscopy and non-contact profilometry were then utilized to directly link slurry thickening behavior to more severe surface scratching of “polished” TEOS wafers. The thickened slurry generated up to 7x more surface scratches than a non-thickened slurry. Both slurry thickening and surface scratching were associated with a dramatic increase in the population of “large” particles (≥300 nm) which were undetectable in the non-thickened slurry. These “large” and potentially scratch-generating particles are believed to instigate measurable surface damage.
    Colloids and Surfaces A Physicochemical and Engineering Aspects 11/2013; · 2.35 Impact Factor
  • 224th ECS Meeting; 10/2013
  • Tara Prasad Pandey, Matthew W Liberatore, Andrew M Herring
    224th ECS Meeting; 10/2013
  • Ye Liu, Junhua Wang, Yushan Yan, Matthew W Liberatore, Andrew M Herring
    224th ECS Meeting; 10/2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: Chemical mechanical polishing (CMP) is an essential technology used in the semiconductor industry to polish and planarize a variety of materials for the fabrication of microelectronic devices (e.g., computer chips). During the high shear (∼1,000,000 s-1) CMP process, it is hypothesized that individual slurry particles are driven together to form large agglomerates (≥0.5 μm), triggering a shear thickening effect. These shear-induced agglomerates are believed to cause defects during polishing. In this study, we examined the shear thickening of a 25 wt% fumed silica slurry with 0.17 M added KCl using in situ small-angle light scattering during rheological characterization (rheo-SALS). The salt-adjusted slurry displays ∼3-fold increase in viscosity at a critical shear rate of 20,000 s-1 during a stepped shear rate ramp from 100 to 25,000 s-1. As the shear rate is reduced back to 100 s-1, the slurry thickens irreversibly displaying a final viscosity that is 100-times greater than the initial viscosity. Corresponding rheo-SALS images indicate the formation of micrometer scale structures (2-3 μm) that directly correlate with the discontinuous and irreversible shear thickening behavior of the fumed silica slurry; these micron scale structures are 10-times the nominal particle diameter (∼0.2 μm). The scattering patterns from the 25 wt% slurry were corroborated through rheo-SALS examination of 27 and 29 wt% slurries (CKCl=0.1 M). All slurries, regardless of ionic strength and solids loading, display scattering patterns that are directly associated with the observed thickening behavior. Scattering was only observable during and after thickening (i.e., no scattering was detected in the absence of thickening). This work serves as the first in situ observation of micrometer scale structures within the fumed silica CMP slurry while under shear.
    Langmuir 09/2013; · 4.38 Impact Factor
  • Unconventional Resources Technology Conference; 08/2013
  • Eric B Webb, Carolyn A Koh, Matthew W Liberatore
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    ABSTRACT: The in situ formation and flow properties of methane hydrates formed from water-in-oil microemulsions composed of water, dodecane, and aerosol OT surfactant (AOT) were studied using a unique high pressure rheometer. AOT microemulsions have high stability (order of months), well characterized composition, and yield reproducible results compared to hydrate studies in water-in-crude oil emulsions. Viscosity increases on the order of minutes upon hydrate formation, and then decreases on the order of hours. If significant unconverted water remained after the initial formation event, then viscosity increases for a time as methane slowly dissolves and converts additional water to hydrate. In addition to transient formation measurements, yield stresses and flow curves are measured for a set of experimental conditions. Hydrate slurry viscosity and yield stress increase with increasing water volume fraction, increasing initial pressure, decreasing temperature, and decreasing formation shear rate. Hydrate slurry viscosity and yield stress are most sensitive to temperature, followed by water volume fraction, initial pressure, and formation shear rate.
    Langmuir 08/2013; · 4.38 Impact Factor
  • 223th ECS Meeting; 05/2013
  • A. M. Herring, M. A. Vandiver, A. M. Maes, H. N. Sarode, E. B. Coughlin, D. M. Knauss, Y. Yan, G. E. Lindberg, C. Knight, G. A. Voth, D. Herbst, T. A. Witten, M. W. Liberatore
    ECS Transactions 03/2013; 50(2):2059-2066.
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    ABSTRACT: Suspensions of corn starch and water are the most common example of a shear thickening system. Investigations into the non-Newtonian flow behavior of corn starch slurries have ranged from simplistic elementary school demonstrations to in-depth rheological examinations that use corn starch to further elucidate the mechanisms that drive shear thickening. Here, we determine how much corn starch is required for the average person to "walk on water" (or in this case, run across a pool filled with corn starch and water). Steady shear rate rheological measurements were employed to monitor the thickening of corn starch slurries at concentrations ranging from 0 to 55wt.% (0-44vol.%). The steady state shear rate ramp experiments revealed a transition from continuous to discontinuous thickening behavior that exists at 52.5wt.%. The rheological data was then compared to macro-scopic (∼5gallon) pool experiments, in which thickening behavior was tested by dropping a 2.1kg rock onto the suspension surface. Impact-induced thickening in the "rock drop" study was not observed until the corn starch concentration reached at least 50wt.%. At 52.5wt.%, the corn starch slurry displayed true solid-like behavior and the falling rock "bounced" as it impacted the surface. The corn starch pool studies were fortified by steady state stress ramps which were extrapolated out to a critical stress value of 67,000Pa (i.e., the force generated by an 80kg adult while running). Only the suspensions containing at least 52.5wt.% (42vol.%) thickened to high enough viscosities (50-250Pas) that could reasonably be believed to support the impact of a man's foot while running. Therefore, we conclude that at least 52.5wt.% corn starch is required to induce strong enough thickening behavior to safely allow the average person to "walk on water".
    Journal of Colloid and Interface Science 02/2013; · 3.55 Impact Factor
  • Ala Bazyleva, Babajide Akeredolu, Matthew W. Liberatore
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    ABSTRACT: Viscosity, μ, of Ugnu heavy oil (North Slope of Alaska, USA) saturated with methane was measured at temperatures from 0 to 60 °C, pressure from 15 to 1800 psi, and shear rate of 0.1–500 s–1 using a high-pressure rheology apparatus constructed for this work. Under all saturated conditions, the oil behaves as a Newtonian fluid. The influence of temperature, pressure, and methane concentration was analyzed, and important regularities in the viscosity were established. A two-variable Antoine-type correlation, μ = f(T, p), with 6 fitting parameters was developed using 48 points on a p,T,μ-diagram for Ugnu oil. Since produced oil is accompanied by sand and water, their influence on the viscosity of Ugnu oil saturated with methane at 1500 psi was also studied. The relative viscosity of the Ugnu oil + water emulsions at temperatures from 2 to 60 °C increased linearly with increasing water concentration from 0 to 20 wt % following the Einstein viscosity model for dilute suspensions. Although possible in the time scale of days, hydrate formation at temperatures below 13 °C (thermodynamic hydrate formation temperature at 1500 psi) did not interfere with the rheological measurements for the emulsions. Due to rapid sand particle sedimentation in methane-saturated Ugnu oil during experimental stages, the impact of sand concentration on the live oil viscosity could not be evaluated. Overall, the viscosity of Ugnu oil as a function of pressure and temperature can be used to simulate the oil’s behavior during production.
    Energy & Fuels 01/2013; 27(2):743–751. · 2.73 Impact Factor
  • Chemical Engineering Education 01/2013; 47:122-132.

Publication Stats

219 Citations
92.87 Total Impact Points


  • 2008–2015
    • Colorado School of Mines
      • Department of Chemical and Biological Engineering
      Golden, Colorado, United States
  • 2009
    • National Renewable Energy Laboratory
      • Biosciences Center
      Golden, Colorado, United States
  • 2006
    • University of Delaware
      • Department of Chemical and Biomolecular Engineering
      Newark, DE, United States