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Displaying 1 - 25 of 136

Measuring domain sizes and compositional heterogeneities in P3HT-PCBM bulk heterojunction thin films with 1H spin diffusion NMR spectroscopy

March 21, 2012
Author(s)
Ryan C. Nieuwendaal, Hyun Wook Ro, David Germack, Regis J. Kline, Calvin Chan, Amit K. Agrawal, David J. Gundlach, David L. VanderHart, Dean M. DeLongchamp
In this manuscript we show that 1H spin diffusion NMR is a valuable method for estimating the domain sizes in thin films of a polymer-fullerene blend for bulk heterojunction (BHJ) photovoltaics. Variations in common BHJ film processing parameters have

NMR Characterization of the Formation Kinetics and Structure of Di-O-Benzylidene Sorbitol Gels Self-Assembled in Organic Solvents

January 19, 2011
Author(s)
David L. VanderHart, Jack F. Douglas, Steven Hudson, Joseph M. Antonucci, Elizabeth A. Wilder
The molecule 1,3:2,4-Di-O-Benzylidene sorbitol (DBS) is a common gelator that forms thermally reversible gels in diverse organic solvents. Solid state 13C and proton NMR techniques, along with electron microscopy, are utilized in an exploratory study of

Photoresist latent and developer images as probed by neutron reflectivity methods

September 16, 2010
Author(s)
Vivek M. Prabhu, Shuhui Kang, David L. VanderHart, Eric K. Lin, Wen-Li Wu
Photoresist materials enable the fabrication of advanced integrated circuits with ever decreasing feature sizes. As next-generation light sources are developed, using extreme ultraviolet light of wavelength 13.5 nm, these highly-tuned formulations must

Synthetic Mica: A Very Promising Substrate for Studying Solid Thin Films by Proton NMR

August 25, 2009
Author(s)
David L. VanderHart, Vivek M. Prabhu, Kristopher Lavery, Cindi L. Dennis
We demonstrate that a synthetic fluorophlogopite mica can be used as a proton-free, diamagnetic substrate for examining solid thin-film samples using conventional solid-state proton NMR experiments. The context of this work extends previous NMR studies on

Thin Film Solid State Proton NMR Measurements Using A Synthetic Mica Substrate: Polymer Blends

August 25, 2009
Author(s)
David L. VanderHart, Vivek Prabhu, Kristopher Lavery, Cindi L. Dennis, Ashwin Rao, Eric K. Lin
We demonstrate that a synthetic fluorophlogopite mica can be used as a proton-free, diamagnetic substrate for examining solid thin-film samples using conventional solid-state proton nuclear magnetic resonance (NMR) experiments. The context of this work

Quantitative Measurement of the Polydispersity in the Extent of Functionalization of Glass Forming Resorcinarenes

May 1, 2009
Author(s)
William E. Wallace, Kathleen M. Flynn, Charles M. Guttman, David L. VanderHart, Vivek M. Prabhu, Anuja De Silva, Nelson Felix, Christopher K. Ober
The polydispersity in the degree of functionalization for two calix[4]resorcinarenes was determined by measuring their molecular mass distribution with matrix-assisted laser desorption/ionization time of flight mass spectrometry. A mathematical method for

Incorporation of Stereo, Regio and Comonomer Defects Into the Crystalline Regions of Isotactic Polypropylene: Results From NMR, Molecular Dynamics and Chemical Shift Calculations

October 16, 2008
Author(s)
David L. VanderHart, Marc R. Nyden, R G. Alamo, L Mandelkern
We have shown that under conditions of crystallization during cooling at 1C/min, substantial amounts of 'defects' of the types a) stereo-mrrm, b) regio-2,1-erythro, c) ethylene-comonomer and d) butylene- comonomer can be found in the crystalline regions
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