Structure-physical Property Relationships Research Articles

Comparison of Novel 1,1-Diphenylethylene Alternating Copolymer and Polystyrene Based Anion Exchange Membranes

This research investigates 1,1-diphenylethylene as a monomer in polymeric ion exchange membranes through the synthesis of a novel alternating copolymer functionalized for ion transport and analysis of mechanical and conductive properties. This will further the development of cost effective and high-performance ion exchange membranes, enabling energy systems that employ ion-transporting membranes, like fuel cells and electrolyzers, to become more economically viable, which in turn would lead to cleaner and more sustainable energy production.The goal of the project is to develop an understanding of chemical structure-physical property relationships to make self-assembling ion-conducting channels in ionomers which have physical properties that prevent the excess swelling that leads to the mechanical failure of membranes. In this vein, anion exchange membranes (AEMs) based on 1,1-diphenylethylene were synthesized and their ion conducting properties and physical state were characterized. Poly(1,1-diphenylethylene-alt-butadiene) alternating copolymer was synthesized via anionic polymerization, then selectively hydrogenated to eliminate double bonds in the polymer backbone. The pendant aromatic rings of the selectively hydrogenated poly(1,1-diphenylethylene-alt-butadiene) were then subjected to quantitatively controlled functionalized by super acid catalyzed Friedel-Crafts bromoalkylation, then aminated with trimethylamine. AEMs spanning a wide range of ion exchange capacities (IECs), 0.39-1.99 milliequiv./gram (meq./g), were made. Conductivity increased with IEC and temperature. Polystyrene based AEMs of similar IECs, 0.38-2.14 meq/g, were synthesized as a standard to compare the 1,1-diphenylethylene based copolymers. The 1,1-diphenylethylene based copolymers had favorable conductivities compared to polystyrene membranes of similar IEC. The glass transition temperature, water uptake, and dimensional swelling were investigated to explain the difference in conductivities between the two species. Figure 1

Synthesis, crystal structure and luminescent properties of p-diphenylsulphone compounds with different substituents

Organic light-emitting diodes (OLEDs) with thermally activated delayed fluorescence (TADF) properties have emerged as cheaper alternatives to high-performance phosphorescent OLEDs with noble-metal-based dopants. In this work, five p-diphenylsulphone derivatives bearing different substitutes (R = H (1a), tert-butyl (1b), trifluoromethyl (1c), carbazolyl (1d) and diphenylamine (1e)) were designed and synthesized. Their photophysical properties were investigated via spectroscopic and theoretical methods. These materials emit violet to blue fluorescence ranging from 326 to 488 nm in dichloromethane solution, and show long-lived luminescence with lifetimes ranging from 7.38 to 13.85 μs. The maximal wavelength of UV absorption and photoluminescence are red-shifted in accordance with not only the electron-donating ability of the terminal substituents, but also the extension of the π-conjugation. The photoluminescent properties as well as crystal structure were investigated with the aim of providing the basis for elucidating structure-physical property relationships in the context of potentially efficient OLED materials.

Identifying potential candidates for donor–acceptor copolymers on a series of 4H-1,2,6-thiadiazines: An electrochemical approach

A series of synthesized small organic molecules based on the 4H-1,2,6-thiadiazine moiety are studied using electrochemistry, to probe their potential as comonomer building blocks for solar-absorbing polymers for organic solar cells. This is the first instance of an electrochemical report for this family of heterocycles. Structure–physical property relationships are identified that can guide future synthetic efforts. Parameters that can influence the properties of the final copolymer such as the choice of electron donor comonomer and the energy level of the fullerene adduct acceptor are factored-in and discussed and the thiadiazines that can meet the requirements are singled-out.

A blue emission polymer: Synthesis, photophysical and electrochemical properties

A novel π-conjugated polymer (PCPyrene) containing N-benzylcarbazole and pyrene units has been synthesized and characterized. The polymer possesses high thermal stability with the decomposition temperature of 440°C. It shows higher fluorescence quantum yields of in solution and solid state, respectively. PCPyrene can emit bright blue-lights both in different organic solutions (440–460nm) and in the solid state (492nm). Compared the emission spectra of PCPyrene in solutions with in solid state, the solid state emission of PCPyrene is significantly red-shifted. Additionally, it is not obvious changes of the solid emission spectra even after being annealed at 150°C under nitrogen for 24h. The electrochemical properties and energy levels of PCPyrene were also investigated by cyclic voltammetry. Furthermore, in order to provide a basis forecasting the structure–physical property relationships, the photophysical properties of PCPyrene have been carefully investigated by fluorescence emission and UV–vis absorption spectra.

ChemInform Abstract: Adventures in Crystal Growth: Synthesis and Characterization of Single Crystals of Complex Intermetallic Compounds

AbstractReview: 162 refs.

Adventures in Crystal Growth: Synthesis and Characterization of Single Crystals of Complex Intermetallic Compounds

The central motivation of this manuscript is to highlight the discovery of novel, highly correlated electron systems. Ternary phases with unusual ground states composed of lanthanides, transition metals, and main group elements exhibit competing behavior leading to potentially novel physical properties. These systems are known to exhibit exotic properties such as unconventional superconductivity, heavy fermion behavior, and unusual forms of magnetism. The flux-growth method provides an avenue to discover and grow large single crystalline materials so that structure–physical property relationships may be determined. The growth of high quality single crystals is necessary to elucidate the intrinsic magnetic, electronic, and thermodynamic properties and has played a significant role in advancing basic and applied materials research. In this manuscript, we review the crystal structures, physical properties, and structure–property correlations of a select group of intermetallic compounds to demonstrate the potential for growth and discovery of materials using main group flux.

The synthesis, crystal structure and photophysical properties of mononuclear platinum(II) 6-phenyl-[2,2′]bipyridinyl acetylide complexes

The synthesis, structural, electrochemical and photophysical properties of a series of 4,6-diphenyl-2,2′-bipyridine platinum(II) complexes bearing σ-alkynyl ancillary ligands were studied. Absorption bands were observed in UV–Vis absorption spectra (maximum peaks range from 431 to 455 nm) and phosphorescence emission maxima varied from 554 nm to 577 nm. Both the UV absorption and photoluminesence emission maxima of the complexes were red-shifted in accordance with not only the electron-donating ability of the para-substituent on the phenylacetylide ligand, but also the extension of the π-conjugated length of the oligo phenylacetylide ligand. The photoluminescent and electrochemical properties as well as crystal structure were investigated with the aim of providing the basis for elucidating structure-physical property relationships in the context of light-emitting materials.

Synthesis, optical properties and crystal structures of carbazole end-capped phenylene ethynylene blue light-emitting materials

A class of highly fluorescent and stable carbazole end-capped phenylene ethynylene compounds have been synthesized and characterized. They show high extinction coefficients of absorption ( λ max abs = 33 0 – 34 0 nm ) and quantum yields of fluorescence ( λ max em = 393 – 396 nm ; Φ F=0.52–0.73) in dichloromethane. The solid state absorptions and emissions are significantly red-shifted from the dilute solution ones ( λ max abs = 358 – 375 nm ; λ max em = 396 – 458 nm ). Their photoluminescent properties and crystal structures have been investigated with the aim of providing a basis for elucidating the structure–physical property relationships. These data indicate their potential use as blue-emitting materials in organic light-emitting diodes (OLEDs).

Correlation between the chemical structure of biodiesel and its physical properties

Biodiesel is a renewable, biodegradable, environmentally benign, energy efficient, substitution fuel which can fulfill energy security needs without sacrificing engine’s operational performance. Thus it provides a feasible solution to the twin crises of fossil fuel depletion and environmental degradation. The properties of the various individual fatty esters that comprise biodiesel determine the overall properties of the biodiesel fuel. In turn, the properties of the various fatty esters are determined by the structural features of the fatty acid and the alcohol moieties that comprise a fatty ester. Better understanding of the structure-physical property relationships in fatty acid esters is of particular importance when choosing vegetable oils that will give the desired biodiesel quality. By having accurate knowledge of the influence of the molecular structure on the properties determined, the composition of the oils and the alcohol used can both be selected to give the optimal performance. In this paper the relationship between the chemical structure and physical properties of vegetable oil esters is reviewed and engineering fatty acid profiles to optimize biodiesel fuel characteristics is highlighted.

Crystal structure–physical property relationships in perovskites

Les structures cristallines de sept composes de structure perovskites sont analysees du point de vue du polyedre de coordination de cation. L'analyse indique qu'un compose ABO 3 de structure perovskite peut etre ferroelectrique si le rapport du volume de l'ion A cuboctaedrique et celui de l'ion B octaedrique vaut exactement S et s'il y a volume d'ion B octaedrique minimum associe aux proprietes ferroelectriques. Application de la methode a PbZrO 3 TiO 3 et PbZnNbO 3

Chemical structure-physical property relationships in polyurethane elastomeric fibres; property variations in polymers containing high hard segment concentrations

A series of linear polyether urethane elastomers has been prepared with soft segment (polyether) content ranging from 0 to 70.8 per cent. The polymers were wet spun; the mechanical and elastic properties of the resulting filaments were examined. Cross-sections of the filaments were examined under cross-polaroids. A macroscopically discernible phase change appears to be related to an inversion of stress-relaxation trends. Specific stress and elongation at break appear also to be affected by the same phase change; minor abnormalities of modulus and specific stress, inside a narrow variation of soft segment concentration, coincide with the appearance of spherulitic structure and birefringence. The elastic behaviour of the filaments is discussed and explained in terms of a physical structure consisting of soft and hard segment domains.

Structure–physical property relationships in peroxide‐cured butadiene–styrene copolymers

AbstractStructure–physical property relationships in high‐vinyl butadiene–styrene copolymers have been determined for samples cured with dicumyl peroxide under the same conditions. Three different structures, butadiene–styrene–butadiene (B–S–B) triblocks, butadiene–styrene (B–S) diblocks, and random butadiene–styrene copolymers, have been examined. Flexural modulus increases with increasing styrene content owing to the inherent stiffness of a polystyrene backbone. Swelling increases whereas hardness and heat distortion temperature decrease with increasing styrene content. This behavior is explained by the decrease in crosslink density with increasing styrene content in all structures. Heat distortion temperatures of the B–S–B and B–S networks are superior to the heat distortion properties of the random structures. The B–S–B structure is the most solvent resistant, followed by the random copolymers, with the B–S structures swelling to the greatest extent. Swelling differences between the B–S–B and random networks decrease with increasing styrene content, while swelling differences between the B–S–B and B–S networks increase with increasing styrene content. These results are explained by the nature of the crosslinking reaction and the number of loose ends present in each network.