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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Polyimidazoles via aromatic nucleophilic displacement

Polyimidazoles (Pl) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl)imidazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The reactions are carried out in polar aprotic solvents such as N,N-dimethylacetamide, sulfolane, N-methylpyrroldinone, dimethylsulfoxide, or diphenylsulfone using alkali metal bases such as potassium carbonate at elevated temperature under nitrogen. The di(hydroxyphenyl)imidazole monomers are prepared by reacting an aromatic aldehyde with a dimethoxybenzil or by reacting an aromatic dialdehyde with a methoxybenzil in the presence of ammonium acetate. The di(methoxyphenyl)imidazole is subsequently treated with aqueous hydrobromic acid to give the di(hydroxyphenyl)imidazole monomer. This synthetic route has provided high molecular weight Pl of new chemical structure, is economically and synthetically more favorable than other routes, and allows for facile chemical structure variation due to the availability of a large variety of activated aromatic dihalides and dinitro compounds.

Connell, John W.↗
DOE OSTI2015

Evolution Of Lattice Structure And Chemical Composition Of The Surface Reconstruction Layer In Li1.2Ni0.2Mn0.6O2 Cathode Material For Lithium Ion Batteries

Voltage and capacity fading of layer structured lithium and manganese rich (LMR) transition metal oxide is directly related to the structural and composition evolution of the material during the cycling of the battery. However, understanding such evolution at atomic level remains elusive. Based on atomic level structural imaging, elemental mapping of the pristine and cycled samples and density functional theory calculations, it is found that accompanying the hoping of Li ions is the simultaneous migration of Ni ions towards the surface from the bulk lattice, leading to the gradual depletion of Ni in the bulk lattice and thickening of a Ni enriched surface reconstruction layer (SRL). Furthermore, Ni and Mn also exhibit concentration partitions within the thin layer of SRL in the cycled samples where Ni is almost depleted at the very surface of the SRL, indicating the preferential dissolution of Ni ions in the electrolyte. Accompanying the elemental composition evolution, significant structural evolution is also observed and identified as a sequential phase transition of C2/m →I41→Spinel. For the first time, it is found that the surface facet terminated with pure cation is more stable than that with a mixture of cation and anion. These findings firmly established how the elemental species in the lattice of LMR cathode transfer from the bulk lattice to surface layer and further into the electrolyte, clarifying the long standing confusion and debate on the structure and chemistry of the surface layer and their correlation with the voltage fading and capacity decaying of LMR cathode. Therefore, this work provides critical insights for designing of cathode materials with both high capacity and voltage stability during cycling.

Environmental Molecular Sciences Laboratory↗
NASA NTRS1992

New Synthesis Of Poly(1,3,4-Oxadiazoles)

Synthesis via aromatic nucleophilic displacement yields new high-molecular-weight polymers. Polymers exhibited good mechanical and thermal properties. Synthetic route provided high-molecular-weight POX of new chemical structure, potentially more economical. Availability of large variety of activated aromatic dihalides, facilitates variation of chemical structures. Exhibit properties making them useful as films. Also useful in coatings, adhesives, moldings, and composites.

Connell, John W.↗
DOE OSTI2017

Unraveling the structure and chemical mechanisms of highly oxygenated intermediates in oxidation of organic compounds

Decades of research on the autooxidation of organic compounds have provided fundamental and practical insights into these processes; however, the structure of many key autooxidation intermediates and the reactions leading to their formation still remain unclear. This work provides additional experimental evidence that highly oxygenated intermediates with one or more hydroperoxy groups are prevalent in the autooxidation of various oxygenated (e.g., alcohol, aldehyde, keto compounds, ether, and ester) and nonoxygenated (e.g., normal alkane, branched alkane, and cycloalkane) organic compounds. These findings improve our understanding of autooxidation reaction mechanisms that are routinely used to predict fuel ignition and oxidative stability of liquid hydrocarbons, while also providing insights relevant to the formation mechanisms of tropospheric aerosol building blocks. The direct observation of highly oxygenated intermediates for the autooxidation of alkanes at 500–600 K builds upon prior observations made in atmospheric conditions for the autooxidation of terpenes and other unsaturated hydrocarbons; it shows that highly oxygenated intermediates are stable at conditions above room temperature. These results further reveal that highly oxygenated intermediates are not only accessible by chemical activation but also by thermal activation. Theoretical calculations on H-atom migration reactions are presented to rationalize the relationship between the organic compound’s molecular structure (n-alkane, branched alkane, and cycloalkane) and its propensity to produce highly oxygenated intermediates via extensive autooxidation of hydroperoxyalkylperoxy radicals. In conclusion, detailed chemical kinetic simulations demonstrate the influence of these additional reaction pathways on the ignition of practical fuels.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Crystal structure and chemical bonding of the intermetallic Zintl phase Yb[subscript 11]AlSb[subscript 9]

High resolution single crystal synchrotron X-ray diffraction data measured at 15(2) K were used to solve the structure of the complex intermetallic Zintl phase, Yb{sub 11}AlSb{sub 9} (space group Iba2), made up of Yb cations and polyanions along with isolated Sb anions. The 15(2) K cell parameters are a = 11.7383(4) {angstrom}, b = 12.3600(4) {angstrom}, c = 16.6796(6) {angstrom}. The temperature dependence of the structure was investigated through high resolution synchrotron powder X-ray diffraction (PXRD) data measured from 90 K to 1000 K. Rietveld refinements of the crystal structure revealed near linear thermal expansion of Yb{sub 11}AlSb{sub 9} with expansion coefficients of 1.49(2) x 10{sup -5} K{sup -1}, 1.71(3) x 10{sup -5} K{sup -1}, 1.13(1) x 10{sup -5} K{sup -1} for a, b and c, respectively. The chemical bonding in Yb{sub 11}AlSb{sub 9} was analyzed using atomic Hirshfeld surfaces, and the analysis supports the presence of the structural elements of Yb cations, [AlSb{sub 4}]{sup 9-} tetrahedra, [Sb{sub 2}]{sup 4-} dimers and isolated Sb{sup 3-} anions. However, indications of interatomic interactions between the Zintl anions and the Yb cations were also observed.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Crystal structure and chemical bonding of novel Li-containing polar intermetallic compound La{sub 11}Li{sub 12}Ge{sub 16}

A novel Li-containing polar intermetallic compound La{sub 11}Li{sub 12}Ge{sub 16} has been synthesized using the high-temperature reaction method and characterized by both powder and single-crystal X-ray diffractions. The title compound crystallized in the orthorhombic crystal system (space group Immm, Z=2, Pearson symbol oI78) with fifteen crystallographically unique atomic positions in the asymmetric unit, and the lattice parameters are refined as a=4.5244(4) A, b=6.9932(6) A, and c=53.043(5) A. The complex crystal structure of the title compound can be described as a 2:1 intergrowth of two closely related compounds: La{sub 2}Li{sub 2}Ge{sub 3} (Ce{sub 2}Li{sub 2}Ge{sub 3}-type) and La{sub 3}Li{sub 4}Ge{sub 4} (Zr{sub 3}Cu{sub 4}Si{sub 4}-type) acting like 'building-blocks' along the c-axis. Six La sites are categorized into three distinct types based on the local coordination environment showing the coordination numbers of 12-14. Three unique Li sites are placed in the centers of local tetrahedra formed by four Ge atoms which eventually construct Ge{sub 2} dimers or 1-dimensional cis-/trans-Ge chains. Theoretical investigations using the tight-binding linear muffin-tin orbital (LMTO) method provide rationales for an improved structural stability and for unique local coordination geometries established by anionic elements including [LiGe{sub 4}] tetrahedra, cis-/trans-Ge chain and Ge{sub 2} dimers. - Graphical abstract: Reported is a novel ternary Li-containing polar intermetallic compound La{sub 11}Li{sub 12}Ge{sub 16}. The complex crystal structure can be viewed as a simple combination of two closely related known compounds acting as 'building-blocks', La{sub 2}Li{sub 2}G{sub 3} and La{sub 3}Li{sub 4}Ge{sub 4}, in a 2:1 stoichiometric ratio. Highlights: Black-Right-Pointing-Pointer A novel Li-containing polar intermetallic compound La{sub 11}Li{sub 12}Ge{sub 16} was synthesized. Black-Right-Pointing-Pointer The complex crystal structure was easily explained as a combination of two known compounds. Black-Right-Pointing-Pointer Theoretical calculations indicated that the Fermi level was located near the pseudogap.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Electronic structure and chemical bonding of {alpha}- and {beta}-CeIr{sub 2}Si{sub 2} intermediate valence compounds

The dimorphism of the intermediate valence ternary cerium silicide CeIr{sub 2}Si{sub 2} in the ThCr{sub 2}Si{sub 2} ({alpha}) and CaBe{sub 2}Ge{sub 2} ({beta}) modifications is addressed in the framework of the density functional theory. The geometry optimization is in good agreement with the experiment and the subsequent establishment of the energy-volume equation of state (EOS) indicates a stabilization of the {beta}-type relative to the {alpha}-type concomitant with the trend of the cerium valence, changing to tetravalent in {beta}-CeIr{sub 2}Si{sub 2}. This is equally shown from the site projected DOS and from the large increase of the electronic contribution to the specific heat. The chemical bonding indicates the strongest bonding interactions within the Ir-Si substructure in both varieties. Stabilization of {beta}-CeIr{sub 2}Si{sub 2} with almost tetravalent cerium is in good agreement with Th{sup IV}Ir{sub 2}Si{sub 2} which exclusively crystallizes in the CaBe{sub 2}Ge{sub 2} type. The EOS behavior of different RIr{sub 2}Si{sub 2} (R=Th, Ce, La) is comparatively discussed. - Graphical abstract: The crystal structures of {alpha}- and {beta}-CeIr{sub 2}Si{sub 2}. Relevant interatomic distances (A), the three-dimensional [Ir{sub 2}Si{sub 2}] networks and the crystallographically independent iridium and silicon sites are indicated. Highlights: Black-Right-Pointing-Pointer Energy stabilization of (HT) {beta}-CeIr{sub 2}Si{sub 2} versus (LT) {alpha}-CeIr{sub 2}Si{sub 2} from DFT methods. Black-Right-Pointing-Pointer Concomitant with the change of Ce valence to tetravalent (HT)-enhanced specific heat. Black-Right-Pointing-Pointer Equations of states for La, Ce and Th members with CeIr{sub 2}Si{sub 2} resembling tetravalent-Th. Black-Right-Pointing-Pointer Chemical bonding shows changes on the {l_brace}Ir{sub 2}Si{sub 2}{r_brace} intralayer and Ce{sup IV}-Ir bonds.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1981

Highlights of 10th plasma chemistry meeting

The chemical structure is given of a film formed by plasma polymerization from pyridine monomers. The film has a hydrophilic chemical structure, its molecular weight is 900, and the molecular system is C55H50N10O3. The electrical characteristics of a plasma polymerized film are described. The film has good insulating properties and was successfully applied as video disc coating. Etching resistance properties make it possible to use the film as a resist in etching. The characteristics of plasma polymer formed from monomers containing tetramethyltin are discussed. The polymer is in film form, displays good adhesiveness, is similar to UV film UV 35 in light absorption and is highly insulating.

Kitamura, K.↗
NASA NTRS1991

New developments in thermally stable polymers

Advances in high-temperature polymers since 1985 are discussed with the emphasis on the chemistry. High-temperature polymers refer to materials that exhibit glass-transition temperatures greater than 200 C and have the chemical structure expected to provide high thermooxidative stability. Specific polymers or series of polymers were selected to show how the chemical structure influences certain properties. Poly(arylene ethers) and polyimides are the two principal families of polymers discussed. Recent work on poly(arylene ethers) has concentrated on incorporating heterocyclic units within the polymer backbone. Recent polyimide work has centered on the synthesis of new polymers from novel monomers, several containing the trifluoromethyl group strategically located on the molecule. Various members in each of these polymer families display a unique combination of properties, heretofore unattainable. Other families of polymers are also briefly discussed with a polymer from an AB maleimidobenzocyclobutene exhibiting an especially attractive combination of properties.

Hergenrother, Paul M.↗
DOE OSTI2018

Potential of pinhão Coat as Constituents of Starch Based Films Using Modification Techniques

The potential of lignocellulosic fibers obtained by dry grinding of pinhão coat as fillers in starch filmogenic solutions for packaging applications was evaluated in this work. To improve the incorporation of this waste into the starch solutions different physical and chemical treatments were conducted. Thereafter, morphology, chemical structure, crystallinity and water absorption of the pinhão coat powders were determined. The composites were also characterized regarding their morphology, chemical structure, crystallinity, mechanical properties, water vapor permeability and hydrophilicity. Poor fiber/matrix adhesion and high water absorption of the fibers were evidenced. Consequently, water vapor permeability of composites was increased by incorporating the fibers. Moreover, mechanical properties were improved and the morphological results were used to support the water absorption differences among the powders. Regarding the food packaging applications, starch/pinhão coat composites appeared as promising materials to reach the requirements of respiring food products.

36 MATERIALS SCIENCE↗
DOE OSTI2018

A further experimental and modeling study of acetaldehyde combustion kinetics

Acetaldehyde is an important intermediate and a toxic emission in the combustion of fuels, especially for biofuels. To better understand its combustion characteristics, a detailed chemical kinetic model describing the oxidation of acetaldehyde has been developed and comprehensively validated against various types of literature data including laminar flame speeds, oxidation and pyrolysis in shock tubes, chemical structure of premixed flames, and low-temperature oxidation in jet-stirred reactors. To extend the validation range, the chemical structure of a counterflow flame fueled by acetaldehyde at 600 Torr has been measured using vacuum ultra-violet photoionization molecular-beam mass spectrometry. In addition, ignition delay times at 10 atm and 700-1100 K were measured in a rapid compression machine, and a negative temperature coefficient (NTC) behavior was observed. Here, the present kinetic model well reproduces the results of various acetaldehyde combustion experiments covering wide ranges of temperatures (300–2300 K) and pressures (0.02–10 atm), and explains well the observed NTC behavior based on the competition between multiple oxidation pathways for the methyl radicals and their self-recombination forming ethane, a relatively stable species at temperatures below 1000 K.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Synthesis, structure and chemical bonding of CaFe{sub 2−x}Rh{sub x}Si{sub 2} (x=0, 1.32, and 2) and SrCo{sub 2}Si{sub 2}

The finding of superconductivity in Ba{sub 0.6}K{sub 0.4}Fe{sub 2}As{sub 2} put the attention on the investigation of compounds that crystallize with ThCr{sub 2}Si{sub 2} structure type such as AT{sub 2}X{sub 2} (A=alkali/alkaline earth/rare earth element; T=transition metal and X=element of the 13–15th group). In this context the silicides CaFe{sub 2}Si{sub 2}, CaFe{sub 0.68(6)}Rh{sub 1.32(6)}Si{sub 2}, CaRh{sub 2}Si{sub 2} and SrCo{sub 2}Si{sub 2} have been synthesized by reaction of the elements under an argon atmosphere. Single crystals were obtained by special heat treatment in welded niobium/tantalum ampoules. The compounds were investigated by means of powder and single crystal X-ray diffraction. All compounds crystallize in the ThCr{sub 2}Si{sub 2}-type structure with space group I4/mmm (No. 139): a=3.939(1) Å, c=10.185(1) Å, R{sub 1}=0.045, 85 F{sup 2} values, 8 variable parameters for CaFe{sub 2}Si{sub 2}; a=4.0590(2) Å, c=9.9390(8) Å, R{sub 1}=0.030, 90 F{sup 2} values, 10 variable parameters for CaFe{sub 0.68(6)}Rh{sub 1.32(6)}Si{sub 2}; a=4.0695(1) Å, c=9.9841(3) Å, R{sub 1}=0.031, 114 F{sup 2} values, 9 variable parameters for CaRh{sub 2}Si{sub 2}; and a=3.974(1) Å, c=10.395(1) Å, R{sub 1}=0.036, 95 F{sup 2} values, 8 variable parameters for SrCo{sub 2}Si{sub 2}. The structure of SrCo{sub 2}Si{sub 2} contains isolated [Co{sub 2}Si{sub 2}]{sup 2−} 2D-layers in the ab-plane whereas in CaFe{sub 2−x}Rh{sub x}Si{sub 2} the [T{sub 2}Si{sub 2}] layers (T=Fe and Rh) are interconnected along the c-axis via Si3Si bonds resulting in a three-dimentional (3D) [T{sub 2}Si{sub 2}]{sup 2−} polyanions and therefore belong to the so-called collapsed form of the ThCr{sub 2}Si{sub 2}-type structure. The SrCo{sub 2}Si{sub 2} and CaRh{sub 2}Si{sub 2} are isoelectronic to the parent 122 iron–pnictide superconductors AeFe{sub 2}As{sub 2} (Ae=alkaline earth elements), whereas CaFe{sub 2}Si{sub 2} is a full substituted variant (As/Si) of CaFe{sub 2}As{sub 2}. The crystal chemistry and chemical bonding in the title compounds are discussed in terms of LMTO band structure calculations and a topological analysis using the Electron Localization Function (ELF). - Graphical abstract: The SrCo{sub 2}Si{sub 2} and CaFe{sub 2−x}Rh{sub x}Si{sub 2} (x==0, 1.32, and 2) crystallize in the ThCr{sub 2}Si{sub 2}-type. The structure of SrCo{sub 2}Si{sub 2} contains isolated [Co{sub 2}Si{sub 2}]{sup 2−} layers in the ab-plane, whereas the [T{sub 2}Si{sub 2}] layers in CaFe{sub 2−x}Rh{sub x}Si{sub 2} are interconnected along the c-axis via Si3Si bonds resulting in a [T{sub 2}Si{sub 2}]{sup 2−} network. - Highlights: • Synthesis and structure of ternary silicides SrCo{sub 2}Si{sub 2} and CaFe{sub 2−x}Rh{sub x}Si{sub 2} (x=0, 1.32, and 2). • The SrCo{sub 2}Si{sub 2} and CaRh{sub 2}Si{sub 2} are isoelectronic to the parent 122 iron–pnictide superconductors AeFe{sub 2}As{sub 2}. • CaFe{sub 2}Si{sub 2} is a full substituted variant (As/Si) of superconductor CaFe{sub 2}As{sub 2}. • The title compounds demonstrate the tunable Si3Si distances.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Lattice cluster theory for polymer melts with specific interactions

Despite the long-recognized fact that chemical structure and specific interactions greatly influence the thermodynamic properties of polymer systems, a predictive molecular theory that enables systematically addressing the role of chemical structure and specific interactions has been slow to develop even for polymer melts. While the lattice cluster theory (LCT) provides a powerful vehicle for understanding the influence of various molecular factors, such as monomer structure, on the thermodynamic properties of polymer melts and blends, the application of the LCT has heretofore been limited to the use of the simplest polymer model in which all united atom groups within the monomers of a species interact with a common monomer averaged van der Waals energy. Thus, the description of a compressible polymer melt involves a single van der Waals energy. As a first step towards developing more realistic descriptions to aid in the analysis of experimental data and the design of new materials, the LCT is extended here to treat models of polymer melts in which the backbone and side groups have different interaction strengths, so three energy parameters are present, namely, backbone-backbone, side group-side group, and backbone-side group interaction energies. Because of the great algebraic complexity of this extension, we retain maximal simplicity within this class of models by further specializing this initial study to models of polymer melts comprising chains with poly(n-α-olefin) structures where only the end segments on the side chains may have different, specific van der Waals interaction energies with the other united atom groups. An analytical expression for the LCT Helmholtz free energy is derived for the new model. Illustrative calculations are presented to demonstrate the degree to which the thermodynamic properties of polymer melts can be controlled by specific interactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1993

Poly(1,2,4-Triazoles) Via Aromatic Nucleophilic Displacement

Synthesis involves nucleophilic displacement of monomers with activated aromatic dihalides. Polymers exhibited desirable physical and thermal properties. Synthesis of polymers provides high-molecular-weight PT of new chemical structures, potentially more economically favorable than other routes, and, because of availability of large variety of activated aromatic dihalides, provides for facile variation of chemical structure. Useful for producing films, moldings, adhesives, and composites.

Connell, John W.↗
DOE OSTI2020

Cryo-nanoimaging of Single Human Macrophage Cells: 3D Structural and Chemical Quantification

X-ray microscopy is increasingly used in biology, but in most cases only in a qualitative way. We present here a 3D correlative cryo Xray microscopy approach suited for the quantification of molar concentrations and structure in native samples at nanometer scale. The multi-modal approach combines X-ray fluorescence and X-ray holographic nanotomography on ‘thick’ frozen-hydrated cells. Applied to complex macrophage cells, we extract the quantification of major and minor elements, as well as the density, in the different organelles. The intracellular landscape shows remarkable elemental differences. This novel analytical microscopy approach will be of particular interest to investigate complex biological and chemical systems in their native environment.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

On-Surface Reactions of Electronically Active Self-Assembled Monolayers for Electrode Work Function Tuning

Self-assembled monolayers (SAMs) help improve the performance of organic electronic devices through interface passivation and enhanced carrier transport. Yet, there is limited information regarding the chemical structure of the SAMs upon functionalization and subsequent thermal treatment. Here, we studied the on-surface reaction of carbazole-derived SAMs on model gold electrodes, focusing on the chemical structure changes induced by thermal treatments. Furthermore, we correlate the microscopic changes with their impact on the electrode’s work function. The carbazole-based SAMs first transform into organometallic complexes. At higher annealing temperatures, SAMs convert to oligomeric complexes. The observed chemical reactions significantly reduce the electrode work function and facilitate electron injection in n-type organic thin-film transistors. Our results highlight the on-surface synthesis of electronically active SAMs as an alternative approach for modifying the work function of electrodes for organic electronics.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Structure of the capsule and lipopolysaccharide O-antigen from the channel catfish pathogen, Aeromonas hydrophila

A hypervirulent A. hydrophila (vAh) pathotype has been identified as the etiologic agent responsible for disease outbreaks in farmed carp species and channel catfish (Ictalurus punctatus) in China and the Southeastern United States, respectively. The possible route of infection has previously been unknown; however, virulence is believed to be multifactorial, involving the production/secretion of several virulence factors, including a high molecular weight group 4 capsular polysaccharide. Here we present chemical structural evidence of a novel capsule- and LPS-associated O-antigen found present in vAh isolated during these disease outbreaks. In this study, the chemical structure of the vAh O-antigen was determined by chemical analysis, Smith degradation, mass spectrometry, and 2D proton and carbon nuclear magnetic resonance (NMR) spectroscopy and found to be unique among described bacterial O-antigens. The O-antigen consists of hexasaccharide repeating units featuring a 4)-α-l-Fucp-(1–3)-β-d-GlcpNAc-(1–4)-α-l-Fucp-(1–4)-β-d-Glcp-(1- backbone, substituted with single residue side chains of α-d-Glcp and α-d-Quip3NAc linked to O-3 of the two fucose residues. The polysaccharide is partially O-acetylated on O-6 of the 4-substituted β-Glcp residue.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2015

Minimization of the auxiliary reagent loading for direct arylation polymerization (DArP) of 2‐bromo‐3‐hexylthiophene

ABSTRACT In this work, we present a powerful set of synthetic strategies aimed at minimization of auxiliary reagent loading for direct arylation polymerization (DArP) of 2‐bromo‐3‐hexylthiophene. As such, we report efficient lowering of Pd(OAc) 2 catalyst loading as well as loading of other auxiliary reagents, such as neodecanoic acid and N , N ‐dimethylacetamide. Unprecedented low loadings of catalyst down to 0.0313% (313 ppm) were achieved, while producing polymer in high yield (91% after Soxhlet extraction), with a high molecular weight (24.2 kDa) and carefully controlled chemical structure thus making the optimized DArP protocol significantly more cost‐effective, convenient, sustainable, and environmentally friendly. The resulting polymer samples were thoroughly investigated in terms of their chemical structure as well as optical, thermal, chain ordering and electronic properties using GPC analysis, 1 H NMR, MALDI, UV–vis, GIXRD spectroscopy, DSC, and SCLC hole mobility measurements. The results demonstrate that the reagent lowering strategies increase the polymer regioregularity from 94.6 to 96.5% as evidenced by 1 H NMR spectra and corroborated by GIXRD, DSC, and UV–vis measurements. Additionally, polymer samples obtained at low reagent loading are more uniformly proton‐terminated as evidenced by 1 H NMR and MALDI end‐group analysis. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53 , 1492–1499

Rudenko, Andrey E.↗