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Dive into the research topics where Eric M. Davis is active.

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Featured researches published by Eric M. Davis.


Journal of Physical Chemistry B | 2013

Water Clustering in Glassy Polymers

Eric M. Davis; Yossef A. Elabd

In this study, water solubility and water clustering in several glassy polymers, including poly(methyl methacrylate) (PMMA), poly(styrene) (PS), and poly(vinylpyrrolidone) (PVP), were measured using both quartz spring microbalance (QSM) and Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy. Specifically, QSM was used to determine water solubility, while FTIR-ATR spectroscopy provided a direct, molecular-level measurement of water clustering. The Flory-Huggins theory was employed to obtain a measure of water-polymer interaction and water solubility, through both prediction and regression, where the theory failed to predict water solubility in both PMMA and PVP. Furthermore, a comparison of water clustering between direct FTIR-ATR spectroscopy measurements and predictions from the Zimm-Lundberg clustering analysis produced contradictory results. The failure of the Flory-Huggins theory and Zimm-Lundberg clustering analysis to describe water solubility and water clustering, respectively, in these glassy polymers is in part due to the equilibrium constraints under which these models are derived in contrast to the nonequilibrium state of glassy polymers. Additionally, FTIR-ATR spectroscopy results were compared to temperature-dependent diffusivity data, where a correlation between the activation energy for diffusion and the measured water clustering was observed.


ACS Applied Materials & Interfaces | 2011

Liquid water transport in polylactide homo and graft copolymers

Eric M. Davis; Grayce Theryo; Marc A. Hillmyer; Richard A. Cairncross; Yossef A. Elabd

The successful design of new biodegradable, renewable resource plastics as replacements to commodity barrier plastics would benefit from an accurate measurement of sorption and diffusion of liquids. In this study, the diffusion of liquid water in amorphous polylactide [PLA] and a PLA graft copolymer, poly(1,5-cyclooctadiene-co-5-norbornene-2-methanol-graft-dl-lactide) [PCNL], was examined with time-resolved Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy. Non-Fickian behavior was observed for all experiments, indicated by a slow approach to steady state due to diffusion and polymer relaxation occurring on similar time scales. This non-Fickian behavior highlights the variability of the sorption isotherms reported in the literature, where others have collected nonequilibrium sorption behavior (instead of true steady-state equilibrium sorption) at different time points and film thicknesses. The dynamic infrared data provided direct evidence for both water diffusion and water-induced polymer relaxation, where both were quantified and regressed to a diffusion-relaxation model to determine the diffusion coefficient and the polymer relaxation time constant. In addition to the successful measurement and modeling of the diffusion-relaxation phenomena for diffusion of a liquid in a nonequilibrium state glassy polymer, this study also determined that the diffusivity of water in the PLA graft copolymer (with only 5 wt % rubber) was 3-fold lower than in the PLA homopolymer.


Advanced Materials | 2015

Using Indentation to Quantify Transport Properties of Nanophase-Segregated Polymer Thin Films

Nichole Nadermann; Eric M. Davis; Kirt A. Page; Christopher M. Stafford; Edwin P. Chan

Indentation of hydrated Nafion thin films reveals that both the in-plane diffusivity of water and the intrinsic permeability of the phase-segregated network decrease dramatically with decreasing film thickness. Using pore-network theory, this decrease in diffusivity is attributed to both an increase in ionic-domain heterogeneity and a reduction in ionic-domain connectivity upon confinement.


ACS Applied Materials & Interfaces | 2018

Role of Surface Chemistry on Nanoparticle Dispersion and Vanadium Ion Crossover in Nafion Nanocomposite Membranes

Allison Jansto; Eric M. Davis

While the introduction of nanoparticles into Nafion membranes has proven to be a viable method to tune the ion selectivity in energy storage technologies such as the vanadium redox flow battery, there still remains a limited understanding of the fundamental mechanism by which the nanoparticles selectively restrict ion crossover. Herein, the surface chemistry and loading of SiO2 nanoparticles (SiNPs) were systematically varied to elucidate the relationship between nanoparticle dispersion (or dispersion state) and vanadium ion permeability in Nafion nanocomposite membranes. Specifically, nanoparticle surface functionalization was altered to achieve both attractive (amine-functionalized) and repulsive (unfunctionalized and sulfonic acid-functionalized) electrostatic interactions between the SiNPs and the ionic groups of Nafion. At a nanoparticle loading of 5 wt %, membranes containing unfunctionalized and amine-functionalized SiNPs demonstrated ∼25% reduction in vanadium ion permeability as compared to unmodified Nafion. Drastically different dispersion states were observed in the electron microscopy images of each nanocomposite membrane, where most notably, aggregates on the order of 500 nm were observed for membranes containing amine-functionalized SiNPs (at all nanoparticle loadings). Results from this work indicate that both dispersion state and surface chemistry of the SiNPs play a critical role in governing the vanadium ion transport in these ionomer nanocomposite membranes.


ACS Macro Letters | 2013

High Hydroxide Conductivity in Polymerized Ionic Liquid Block Copolymers

Yuesheng Ye; Sharon Sharick; Eric M. Davis; Karen I. Winey; Yossef A. Elabd


Macromolecules | 2012

Nonequilibrium Sorption of Water in Polylactide

Eric M. Davis; Matteo Minelli; Marco Giacinti Baschetti; Giulio C. Sarti; Yossef A. Elabd


Polymer | 2011

The influence of thermal history on structure and water transport in Parylene C coatings

Eric M. Davis; Nicholas M. Benetatos; William F. Regnault; Karen I. Winey; Yossef A. Elabd


Advanced Functional Materials | 2016

Stiff and Transparent Multilayer Thin Films Prepared Through Hydrogen-Bonding Layer-by-Layer Assembly of Graphene and Polymer

Fangming Xiang; Dorsa Parviz; Tara M. Givens; Ping Tzeng; Eric M. Davis; Christopher M. Stafford; Micah J. Green; Jaime C. Grunlan


ACS Macro Letters | 2014

Elucidating Water Transport Mechanisms in Nafion Thin Films

Eric M. Davis; Christopher M. Stafford; Kirt A. Page


Soft Matter | 2014

Prediction and validation of diffusion coefficients in a model drug delivery system using microsecond atomistic molecular dynamics simulation and vapour sorption analysis.

Christopher Forrey; David M. Saylor; Joshua S. Silverstein; Jack F. Douglas; Eric M. Davis; Yossef A. Elabd

Collaboration


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Kirt A. Page

National Institute of Standards and Technology

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Christopher M. Stafford

National Institute of Standards and Technology

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Edwin P. Chan

National Institute of Standards and Technology

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Nichole Nadermann

National Institute of Standards and Technology

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Christopher L. Soles

National Institute of Standards and Technology

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Karen I. Winey

University of Pennsylvania

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