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Search Publications by: Christopher Stafford (Fed)

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Displaying 26 - 50 of 197

Unexpectedly Strong Size-Sieving Ability in Carbonized Polybenzimidazole for Membrane H2/CO2 Separation

November 21, 2019
Author(s)
Maryam Omidvar, Hien Nguyen, Liang Huang, Cara Doherty, Anita Hill, Christopher Stafford, Xianshe Feng, Mark Swihart, Haiqing Lin
Polymers with high permeability and strong size-sieving ability are needed for H2/CO2 separation at temperatures ranging from 100 °C to 300 °C to enable an energy-efficient pre- combustion CO2 capture process. However, such polymers usually suffer from a

A general approach to multicomponent metal-decorated crumpled reduced graphene oxide nanocomposites using a flame-based process

September 25, 2019
Author(s)
Mohammad M. Mohammadi, Shikuan Shao, Santosh S. Gunturi, Anirudh R. Raghavan, Naveshkaanth Alexander, Christopher Stafford, Raymond D. Buchner, Mark Swihart
A general approach to multicomponent metal-decorated crumpled reduced graphene oxide nanocomposites using a flame-based process Mohammad Moein Mohammadi1, Shikuan Shao1, Santosh Srivatsa Gunturi1, Anirudh Ravi Raghavan1, Naveshkaanth Alexander1

Sequential and one-pot post-polymerization modification reactions of thiolactone-containing polymer brushes

August 19, 2019
Author(s)
Cassandra M. Reese, Brittany J. Thompson, Phillip K. Logan, Christopher Stafford, Derek L. Patton, Michael Blanton
Thiolactone chemistry has garnered significant attention as a powerful post-polymerization modification (PPM) route to mutlifunctional polymeric materials. Here, we apply this versatile chemistry to the fabrication of ultrathin, multifunctional polymer

Effect of Adjacent Hydrophilic Polymer Thin Films on Physical Aging and Residual Stress in Thin Films of Poly(butylnorbornene-ran-hydroxyhexafluoroisopropyl norbornene)

June 22, 2019
Author(s)
Elizabeth A. Lewis, Christopher Stafford, Bryan D. Vogt
The properties of thin supported polymer films can be dramatically impacted by the substrate upon which it resides. A simple way to alter the properties of the substrate (chemistry, rigidity, dynamics) is by coating it with an immiscible polymer. Here we

Controlled Growth of Polyamide Films atop Homogeneous and Heterogeneous Hydrogels using Gel- Liquid Interfacial Polymerization

May 22, 2019
Author(s)
Mengyuan Wang, Christopher Stafford, Lewis M. Cox, Adrienne K. Blevins, Masoud Aghajani, Jason Killgore, Yifu Ding
Interfacially polymerized polyamide (PA) layers dictate the permselective performance of thin film composite (TFC) membranes. Extensive effort has been focused on understanding and ultimately controlling the structure and morphology of the PA layers on

Tuning the Relaxation of Nano-Patterned Polymer Films with Polymer-Grafted Nanoparticles: Observation of Entropy-Enthalpy Compensation

November 6, 2018
Author(s)
Sonal Bhadauriya, Xiaoteng Wang, Jack F. Douglas, Praveen Pitliya, Jianan Zhang, Dharmaraj Raghavan, Michael R. Bockstaller, Christopher Stafford, Alamgir Karim
Polymer films provide a versatile "plastic" material in which complex functional relief patterns can be imprinted with a resolution down to tens of nanometers. However, the utility of such patterned materials is limited by the tendency of imprinted

Short-time dental resin biostability and kinetics of enzymatic degradation

May 9, 2018
Author(s)
Xiaohong Wang, Sheng Song, Lei Chen, Christopher M. Stafford, Jirun Sun
Resin biostability is an important concern regarding the durability of methacrylate-based dental resin restorations. Current resin biostability evaluation methods take considerable time, from weeks to months, and provide no short-time kinetics of resin

Buckling Instabilities in Polymer Brush Surfaces via Postpolymerization Modification

October 30, 2017
Author(s)
Wei Guo, Cassandra M. Reese, Li Xiong, Phillip K. Logan, Brittany J. Thompson, Christopher Stafford, Anton Ievlev, Bradley S. Lokitz, Olga S. Ovchinnikova, Derek L. Patton
We report a simple route to engineer ultrathin polymer brush surfaces with wrinkled and creased morphologies using postpolymerization modification (PPM), where the length scale of the buckled features can be tuned using PPM reaction time and sequence. We

Wrinkling-to-delamination transition in thin polymer films on compliant substrates

October 9, 2017
Author(s)
Adam J. Nolte, Jun Y. Chung, Chelsea S. Davis, Christopher Stafford
Compressing a thin, stiff film attached to a thick, compliant substrate can lead to a number of different modes of mechanical deformation depending upon the material properties of the system. In this article we explore direct transitions from surface

Film Confinement Induced "Jump-Percolation" Wetting Transition in Amphiphilic Block Copolymer Films

October 1, 2017
Author(s)
Namrata Salunke, Asritha Nallapaneni, Guangcui Yuan, Christopher Stafford, Hui Niu, Matthew D. Shawkey, R. A. Weiss, Alamgir Karim
A sharp surface wettability transition with varying film thickness dependent morphology was observed in cast films of an amphiphilic triblock copolymer comprised of poly(2-(N-ethylperfluotooctanesulfonamido) ethyl methylacrylate), poly(FOSM), and poly(N,N'

Entropy-Driven Segregation of Polymer-Grafted Nanoparticles under Confinement

February 22, 2017
Author(s)
Ren Zhang, Bongjoon Lee, Christopher Stafford, J. F. Douglas, Andrey V. Dobrynin, Michael R. Bockstaller, Alamgir Karim
Polymer-grafted nanoparticles (PGNPs) have attracted much attention due to the enhanced dispersion in polymeric materials via an interacting brush layer that enables unique functionality and stability. The miscibility and organization of nanoparticles

Scalable Manufacturing of Layer-by-Layer Membranes for Water Purification

December 1, 2016
Author(s)
Christopher M. Stafford
Water is critical to the health and security of our nation. And as our population expands and water scarcity becomes a reality, we as a people need to think creatively on how we safeguard access to clean water. The manufacturing of today’s state-of-the-art

Ultraviolet/Ozone as a tool to control grafting density in surface-initiated controlled-radical polymerizations via ablation of bromine

July 21, 2016
Author(s)
Richard J. Sheridan, Sara V. Orski, Shinichiro Muramoto, Christopher M. Stafford, Kathryn L. Beers
We used an ultraviolet-ozone (UVO) cleaner to create substrates for atom-transfer radical polymerization (ATRP) with varying surface initiator coverage. We collected complementary time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray

Pattern-Directed Phase Separation of Polymer-Grafted Nanoparticles in a Homopolymer Matrix

May 12, 2016
Author(s)
Ren Zhang, Bongjoon Lee, Michael R. Bockstaller, Sanat K. Kumar, Christopher Stafford, Jack F. Douglas, Dharmaraj Raghavan, Alamgir Karim
The controlled organization of nanoparticle (NP) constituents into superstructures of well- defined shape, composition and connectivity represents a continuing challenge in the development of novel hybrid materials for many technological applications. We

Enhancing Single-Wall Carbon Nanotube Properties Through Controlled Endohedral Filling

May 10, 2016
Author(s)
Jochen I. Campo, Yanmei Piao, Stephanie Lam, Christopher Stafford, Jason K. Streit, Jeffrey R. Simpson, Angela R. Hight Walker, Jeffrey Fagan
Chemical control of the endohedral volume of single-wall carbon nanotubes (SWCNTs) via liquid-phase filling is demonstrated to be a facile strategy to controllably modify properties of the nanotubes in manners significant for processing and proposed

Interlaboratory study towards a climate-specific test: spectroscopic characterizations of EVA in glass/EVA/glass systems

February 23, 2016
Author(s)
Jae Hyun Kim, Christopher M. Stafford, Yadong Lyu, Li C. Yu, Chiao-Chi Lin, Tinh Nguyen, Xiaohong Gu
EVA as an encapsulant material is exposed to various UV irradiation, thermal cycles, and humidity conditions. Degradation of EVA can reduce not only power generation due to yellowing, but also a structural integrity of a PV module. In order to investigate

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

February 8, 2016
Author(s)
Fangming Xiang, Dorsa Parviz, Tara M. Givens, Ping Tzeng, Eric Davis, Christopher Stafford, Micah J. Green, Jaime C. Grunlan
Since its discovery in 2004, graphene has been intensely studied due to its high elastic modulus, thermal conductivity, electrical conductivity, and gas impermeability. Although it is possible to use small quantities of graphene sheets for fundamental