Charles Pittman
Mississippi State University, Chemistry, Faculty Member
Page 1. Computational Modeling for the Development of CVD SiC Epitaxial Growth Processes. G. Melnychuk 1, Y. Koshka 1 S. Yingquan 1, M. Mazzola 1, CU Pittman, Jr.2 1 Department of Electrical & Computer Engineering ...
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Organodithiols with two distal thiols have been used extensively in gold and silver nanoparticle (AuNP and AgNP) applications. However, understanding the structures and conformations of organodithiols on these nanoparticles is... more
Organodithiols with two distal thiols have been used extensively in gold and silver nanoparticle (AuNP and AgNP) applications. However, understanding the structures and conformations of organodithiols on these nanoparticles is challenging. Reported in this work is a combined surface enhanced Raman spectroscopy (SERS), transmission electron microscope (TEM), inductively coupled plasma mass-spectrometry (ICP-MS), and localized surface plasmonic resonance (LSPR) study of alkyldithiol (ADT, (HS-(CH 2) n-SH, n = 2, 4, and 6) interactions with AuNPs and AgNPs in water. These complementary techniques revealed a series of new insights that would not be possible using individual methods. A large-fraction of ADTs lies flat on AuNP surfaces. The upright ADTs are dimerized horizontally through disulfide-bond, or remain as monothiolates on the AuNP surfaces. The possibility of a significant amount of vertically disulfide-linked organodithiol on the surface is excluded on the basis of ICP-MS and AuNP LSPR experiments. ADTs induced significant AgNP disintegrations in which ADTs are predominantly in dithiolate forms. This work highlights the extraordinary complexity of organodithiol interactions with plasmonic nanoparticles. The insights provided in this work will be important for enhancing fundamental understanding of the structure and properties of organothiol-functionalized AgNPs and AuNPs.
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Evidence indicating metal clusters are catalysts in organic reactions was obtained in experimental studies on the hydroformylation of 1-pentene and 2-pentene catalyzed by Coâ(CO)â(Jâ-CO)â(Jâ-PCâHâ)â and related cobalt clusters;... more
Evidence indicating metal clusters are catalysts in organic reactions was obtained in experimental studies on the hydroformylation of 1-pentene and 2-pentene catalyzed by Coâ(CO)â(Jâ-CO)â(Jâ-PCâHâ)â and related cobalt clusters; hydroformylation of olefins, e.g., styrene or cis-2-butene, with heteronuclear cobalt clusters containing cobalt and iron and either molybdenum or chromium; and the photocatalytic hydrosilation of ketones with the heteronuclear clusters.
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The radiation degradation behavior of methyl ..cap alpha..-chloroacrylate (MCA) and methacrylonitrile (MCN) copolymers has been investigated as part of a program to develop high-sensitivity polymeric resists for integrated circuit... more
The radiation degradation behavior of methyl ..cap alpha..-chloroacrylate (MCA) and methacrylonitrile (MCN) copolymers has been investigated as part of a program to develop high-sensitivity polymeric resists for integrated circuit manufacture. High-molecular-weight copolymers were prepared by emulsion techniques. Several different copolymer compositions were prepared varying from 19 to 68 mol % MCA. These copolymers were fractionated and then subjected to ..gamma.. irradiation from a â¶Â°Co source. The G/sub s/ - G/sub x/, G/sub s/ - 4G/sub x/ values were determined from anti M/sub n/â»Â¹ and anti M/sub w/â»Â¹ versus dose plots, and the G/sub s/ and G/sub x/ values were then calculated. Molecular weights of both unirradiated and irradiated polymers were analyzed by membrane osmometry and gel permeation chromatography. All copolymers exhibited higher degradation susceptibilities than that of poly(methyl methacrylate), which has G/sub s/ = 1.3. The individual G/sub s/ and G/sub x/ values of the copolymers were found to fall between those of the two homopolymers, poly(methyl ..cap alpha..-chloracrylate) (G/sub s/ = 6.0) and polymethacrylonitrile (G/sub s/ = 3.1). The dependence of G/sub s/ and G/sub x/ values on molecular weight was minor. The crosslinking susceptibility of the poly(methyl ..cap alpha..-chloroacrylate) (G/sub x/ = 0.8) was greatly decreased by copolymerization with MCN. Relatively small amounts of MCN caused alarge drop in G/sub x/, i.e., G/sub x/ = 0.15 at 32% MCN and G/sub x/ = 0.03 at 51% MCN. The observation could be attributed to the decreasing probability that crosslinking sites, in the MCA monomer units on adjacent chains, would lie in close proximity. 3 figures, 8 tables.
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... XXVII. Radical-Initiated Polymerization and Copolymerization of 7 -( 2,4-Hexadien-1 -yl Actylate) tricarbonyliron CHARLES U. PITTMAN, JR., ORVAL E. AYERS, and SAMUEL P. McMANUS Department of Chemistry University of Alabama University,... more
... XXVII. Radical-Initiated Polymerization and Copolymerization of 7 -( 2,4-Hexadien-1 -yl Actylate) tricarbonyliron CHARLES U. PITTMAN, JR., ORVAL E. AYERS, and SAMUEL P. McMANUS Department of Chemistry University of Alabama University, Alabama 35807 and ...
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