scholarly journals Laterally substituted symmetric and nonsymmetric salicylideneimine-based bent-core mesogens

2012 ◽  
Vol 8 ◽  
pp. 129-154 ◽  
Author(s):  
Sonja Findeisen-Tandel ◽  
Wolfgang Weissflog ◽  
Ute Baumeister ◽  
Gerhard Pelzl ◽  
H N Shreenivasa Murthy ◽  
...  
Keyword(s):  
Physical Properties ◽  
Liquid Crystalline ◽  
Optical Measurements ◽  
Disruptive Effect ◽  
Structure Property ◽  
Scanning Calorimetry ◽  
Structure Property Relationships ◽  
New Findings ◽  
Phenyl Rings ◽  
Intramolecular Hydrogen

Bent-core mesogens have gained considerable importance due to their ability to form new mesophases with unusual properties. Relationships between the chemical structure of bent-core molecules and the type and physical properties of the formed mesophases are relatively unknown in detail and differ strongly from those known for calamitic liquid crystals. In this paper symmetric and nonsymmetric five-ring salicylideneaniline-based bent-core mesogens are presented, and the effect of lateral substituents attached at the outer phenyl rings (F, Cl, Br) or the central phenyl ring (CH3) on the liquid-crystalline behaviour and on the physical properties is studied. Corresponding benzylideneaniline-based compounds were additionally prepared in order to study the influence of the intramolecular hydrogen bond. The occurring mesophases were investigated by differential scanning calorimetry, polarising microscopy, X-ray diffraction and dielectric and electro-optical measurements. The paper reports on new findings with respect to the structure–property relationships of bent-core mesogens. On one hand, the disruptive effect of laterally substituted halogen atoms, F, Cl and Br, on the mesophase behaviour of three isomeric series was much lower than expected. On the other hand, an increase of the clearing temperature by 34 K was observed, caused by small lateral substituents. The electro-optical behaviour, especially the type of polar switching and corresponding molecular movements, is sensitive to variations in the molecular structure.

Synthesis and Liquid Crystalline Properties of New Chiral Monomers and Polysiloxanes

2013 ◽  
Vol 815 ◽  
pp. 747-751
Author(s):  
Jian She Hu ◽  
Yi Nan Liu ◽  
Ya Ting Song ◽  
Di Wang
Keyword(s):  
Liquid Crystalline ◽  
Structure Property ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Cholesteric Phase ◽  
Crystalline Materials ◽  
H Nmr ◽  
Structure Property Relationships ◽  
Potential Applications ◽  
Liquid Crystalline Materials

To study the structure-property relationships of new chiral liquid crystalline materials based on menthol and explore their potential applications, a monomer 4-(4-allyloxybenzoyloxy) phenyl-4-menthyl-oxyacetyloxybiphenyl-4-carboxylate (LCM) and the corresponding homopolymer (LCP) were synthesized. The chemical structure was characterized by FT-IR and 1H NMR. The liquid crystalline properties were investigated by differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, and X-ray diffraction. The monomer LCM formed a cholesteric phase when a flexible linkage chain was inserted between the mesogenic core and the terminal menthyl groups by reducing the steric effect. The homopolymer LCP exhibited a batonnet texture of a smectic A phase.

scholarly journals Synthesis, liquid crystalline behaviour and structure–property relationships of 1,3-bis(5-substituted-1,3,4-oxadiazol-2-yl)benzenes

2020 ◽  
Vol 16 ◽  
pp. 149-158
Author(s):  
Afef Mabrouki ◽  
Malek Fouzai ◽  
Armand Soldera ◽  
Abdelkader Kriaa ◽  
Ahmed Hedhli
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystalline ◽  
Dipole Moments ◽  
Structure Property ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Rigid Core ◽  
X Ray ◽  
Structure Property Relationships ◽  
Crystal Properties

Two series containing 1,3-bis(1,3,4-oxadiazol-2-yl)benzene as a rigid core (RC) and alkyl or perfluoroalkyl as terminal chains were synthesized and characterized. Liquid crystal properties of the synthesized compounds have been investigated by polarizing optical microscopy, differential scanning calorimetry and X-ray diffraction techniques. Conformation effects of the synthesized products on the dipole moments were also investigated.

Synthesis and structure-property relationships of novel poly(p-xylylene)s with aromatic substituents

e-Polymers ◽  
2001 ◽  
Vol 1 (1) ◽  
Author(s):  
Michael Ishaque ◽  
Ralf Wombacher ◽  
Joachim H. Wendorff ◽  
Andreas Greiner
Keyword(s):  
Chemical Vapor ◽  
Coupling Reaction ◽  
Structure Property ◽  
Ambient Conditions ◽  
Structure Property Relationships ◽  
Aryl Bromides ◽  
Phenyl Rings ◽  
Type Coupling ◽  
Derivatives Of ◽  
Conversion Of Alcohols

AbstractTwo step synthesis of educts for the synthesis of poly(p-xylylene)s was accomplished by Grignard-type coupling reaction of 4-bromotoluene and different aldehydes or p-tolylaldehyde and different aryl bromides followed by conversion of alcohols into corresponding chlorides. Derivatives of poly(p-xylylene) (PPX) were obtained by vapor phase pyrolysis/chemical vapor deposition (CVD) or Gilch-type polymerization of these chlorides. Functional groups along the PPX main chain were introduced by substituted phenyl rings in a-position. The resulting PPXs are soluble under ambient conditions and are amorphous in the solid state. The glass transition temperatures varied only slightly with substituents on the phenyl ring in a-position. Significant enhancement by substituents was found for the thermal stability under nitrogen and a considerable decrease of the surface energies by fluorinated substituents.

scholarly journals Synthesis and Characterization of Photoluminescence Liquid Crystals Based on Flexible Chain-Bearing Pentafluorinated Bistolanes

Crystals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 603
Author(s):  
Shigeyuki Yamada ◽  
Masaya Sato ◽  
Tsutomu Konno
Keyword(s):  
Phase Transition ◽  
Liquid Crystals ◽  
Oxygen Atom ◽  
Liquid Crystalline ◽  
Color Change ◽  
Photophysical Properties ◽  
Structure Property ◽  
Flexible Chain ◽  
Structure Property Relationships ◽  
Chiral Nematic

The liquid-crystalline (LC) and photophysical properties of molecules are very sensitive to their electronic and molecular aggregate structures. Herein, to shed light on the structure–property relationships of pentafluorinated bistolane-based photoluminescence (PL) liquid crystals (PLLCs) previously reported by our group, we synthesized pentafluorinated bistolanes with variable flexible chains and evaluated their LC and photophysical properties. The incorporation of an oxygen atom (to afford a 2-methoxyethoxy unit) or an oxygen atom and a methyl group (to afford a 1-methoxyprop-2-oxy unit) into the flexible butoxy chain significantly decreased the temperature of the crystalline-to-LC phase transition, and a chiral nematic phase comprising helical molecular aggregates was observed for the chiral 1-methoxyprop-2-oxy group–bearing bistolane. The synthesized bistolanes exhibited strong blue PL in both solution and crystalline phases; the featuring PL characteristics were maintained in the LC phase (produced by the crystalline-to-LC phase transition) except for a slight PL color change. Thus, it was concluded that the PL behavior of pentafluorinated bistolanes can be modulated by the choice of a suitable flexible chain, and the obtained insights are believed to facilitate the application of PLLCs in thermosensing PL materials.

scholarly journals Predicting permeability via statistical learning on higher-order microstructural information

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Magnus Röding ◽  
Zheng Ma ◽  
Salvatore Torquato
Keyword(s):  
Neural Networks ◽  
Physical Properties ◽  
Specific Surface ◽  
Correlation Functions ◽  
Quantitative Structure ◽  
Structure Property ◽  
Complex Materials ◽  
Structure Property Relationships ◽  
Quantitative Structure Property Relationships ◽  
Point Correlation

Abstract Quantitative structure–property relationships are crucial for the understanding and prediction of the physical properties of complex materials. For fluid flow in porous materials, characterizing the geometry of the pore microstructure facilitates prediction of permeability, a key property that has been extensively studied in material science, geophysics and chemical engineering. In this work, we study the predictability of different structural descriptors via both linear regressions and neural networks. A large data set of 30,000 virtual, porous microstructures of different types, including both granular and continuous solid phases, is created for this end. We compute permeabilities of these structures using the lattice Boltzmann method, and characterize the pore space geometry using one-point correlation functions (porosity, specific surface), two-point surface-surface, surface-void, and void-void correlation functions, as well as the geodesic tortuosity as an implicit descriptor. Then, we study the prediction of the permeability using different combinations of these descriptors. We obtain significant improvements of performance when compared to a Kozeny-Carman regression with only lowest-order descriptors (porosity and specific surface). We find that combining all three two-point correlation functions and tortuosity provides the best prediction of permeability, with the void-void correlation function being the most informative individual descriptor. Moreover, the combination of porosity, specific surface, and geodesic tortuosity provides very good predictive performance. This shows that higher-order correlation functions are extremely useful for forming a general model for predicting physical properties of complex materials. Additionally, our results suggest that artificial neural networks are superior to the more conventional regression methods for establishing quantitative structure–property relationships. We make the data and code used publicly available to facilitate further development of permeability prediction methods.

Investigation of the Structure-Property Relationships of Improved Low Compression Set Nitrile Rubbers

1981 ◽  
Vol 54 (1) ◽  
pp. 170-180 ◽  
Author(s):  
D. M. Chang
Keyword(s):  
Molecular Weight ◽  
Physical Properties ◽  
Structure And Properties ◽  
Structure Property ◽  
Compression Set ◽  
Structure Property Relationships ◽  
Polymer Properties ◽  
Nitrile Rubbers ◽  
New Type ◽  
The Right

Abstract The effect of polymer structures on the rubber processing and physical properties of the improved Hycar 1090 low compression set nitrile rubbers was investigated. The molecular weight and acrylonitrile content of a polymer are important variables in determining the compound processing and vulcanizate physical properties. Within the range of 21 to 88 Mooney, a blend of high and low Mooney polymers has approximately the same properties as those from a single polymer of the same Mooney viscosity. The molecular weight distribution was not significantly broadened to become an important factor affecting the polymer properties. All polymers with Mooney viscosities from 21 to 88 showed good properties. An understanding of the structure and properties of this new type of NBR, will help in choosing the right kind of polymer for particular applications.

scholarly journals Heterometal Grafted metalla-ynes and Poly(metalla-ynes): A Review on Structure–Property Relationships and Applications

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3654
Author(s):  
Rayya A. Al-Balushi ◽  
Ashanul Haque ◽  
Idris J. Al-Busaidi ◽  
Houda Al-Sharji ◽  
Muhammad S. Khan
Keyword(s):  
Physical Properties ◽  
Main Chain ◽  
Functional Materials ◽  
Photo Luminescence ◽  
Structural Features ◽  
Side Chain ◽  
Structure Property ◽  
Molecular Scaffolds ◽  
Structure Property Relationships ◽  
Rigid Rod

Metalla-ynes and poly(metalla-ynes) have emerged as unique molecular scaffolds with fascinating structural features and intriguing photo-luminescence (PL) properties. Their rigid-rod conducting backbone with tunable photo-physical properties has generated immense research interests for the design and development of application-oriented functional materials. Introducing a second d- or f-block metal fragment in the main-chain or side-chain of a metalla-yne and poly(metalla-yne) was found to further modulate the underlying features/properties. This review focuses on the photo-physical properties and opto-electronic (O-E) applications of heterometal grafted metalla-ynes and poly(metalla-ynes).

Structural and Physical Properties in the Bi‐Sr‐Cu‐O System

1989 ◽  
Vol 169 ◽  
Author(s):  
S. A. Sunshine ◽  
L. F. Schneemeyer ◽  
R. M. Fleming ◽  
A. T. Fiory ◽  
S. Martin ◽  
...  
Keyword(s):  
Solid Solution ◽  
Physical Properties ◽  
Structural Model ◽  
Structure Property ◽  
Structure Property Relationships

AbstractThe structure/property relationships in the Bi‐Sr‐Cu‐O system near Bi2Sr2CuOx have been investigated. The properties and phase limits of the solid solution Bi2+xSr2_yCuO6±δ have been determined and a structural model for Bi2Sr2CuO6 is proposed.

scholarly journals Characterization of Composition and Structure–Property Relationships of Commercial Post-Consumer Polyethylene and Polypropylene Recyclates

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1574
Author(s):  
Markus Gall ◽  
Paul J. Freudenthaler ◽  
Joerg Fischer ◽  
Reinhold W. Lang
Keyword(s):  
Thermo Gravimetric Analysis ◽  
Charpy Impact ◽  
Impact Testing ◽  
Gravimetric Analysis ◽  
Structure Property ◽  
Scanning Calorimetry ◽  
Melt Flow Rate ◽  
Impact Performance ◽  
Structure Property Relationships ◽  
Composition And Structure

The current efforts in moving closer towards a circular plastics economy puts massive pressure on recycled plastics, especially recycled polyethylene (rPE) and recycled polypropylene (rPP) to enter new markets. Their market penetration remained low so far, despite PE and PP constituting the largest share of plastic wastes. However, with the current imperative of more circularity comes a new focus on performance of recyclates. Hence, a detailed understanding of composition and structure–property relationships of post-consumer recyclates has to be developed. Five recycling companies from the Austrian and German markets were asked to supply their purest high-quality rPE and rPP grades. These were characterized by differential scanning calorimetry (DSC), thermo-gravimetric analysis (TGA), and Fourier-transform infrared (FTIR) spectroscopy, and micro-imaging. Technological characterization included density measurements, determination of the melt flow rate (MFR), and Charpy impact testing. All recyclates contained diverse contaminants and inclusions ranging from legacy fillers like calcium carbonate to polymeric contaminants like polyamides or polyolefin cross-contamination. The overall amount, size, and distribution of contaminants varied significantly among suppliers. Furthermore, first structure–property relationships for polyolefin recyclates that link inorganic content and polymeric purity with density and impact performance could be derived.

Thermal and Spectral Analysis of Novel Amide-Tethered Polymers from Poly(allylamine)

2016 ◽  
Vol 69 (4) ◽  
pp. 458
Author(s):  
Paolo N. Grenga ◽  
Matthew J. Nethercott ◽  
Ayeisca E. Mateo ◽  
Mathew Patenaude ◽  
Todd Hoare ◽  
...  
Keyword(s):  
Solid State Nmr ◽  
Differential Scanning Calorimetry Analysis ◽  
Structure Property ◽  
Scanning Calorimetry ◽  
Multilayer Systems ◽  
Amide Linkage ◽  
Structure Property Relationships ◽  
Modified Polymers ◽  
Tethered Polymers ◽  
Allylamine Hydrochloride

Post-polymerization modification of poly(allylamine hydrochloride) was applied to synthesize a library of amide-linked polyelectrolytes with tethered aliphatic, aromatic, and cubyl moieties. The efficacy of amidation was determined to be between 12 and 98 %, depending on the electronics, sterics, and solubility of the amide linkage. 13C solid-state NMR was used to further validate their structure. Thermogravimetric analysis and differential scanning calorimetry analysis indicated that none of the new polymers displayed a classic melt/freeze profile, but all displayed onset decomposition temperatures smaller than 215°C. We anticipate that the structure–property relationships observed in the resulting library of graft-modified polymers can facilitate better understanding of how to design polyelectrolytes for the construction of well-defined multilayer systems.

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