scholarly journals The difluoromethylene (CF2) group in aliphatic chains: Synthesis and conformational preference of palmitic acids and nonadecane containing CF2 groups

2014 ◽  
Vol 10 ◽  
pp. 18-25 ◽  
Author(s):  
Yi Wang ◽  
Ricardo Callejo ◽  
Alexandra M Z Slawin ◽  
David O’Hagan
Keyword(s):  
Palmitic Acid ◽  
Conformational Stability ◽  
Phase Behaviour ◽  
Aliphatic Chain ◽  
Melting Points ◽  
Scanning Calorimetry ◽  
Dipolar Relaxation ◽  
Design Modification ◽  
Palmitic Acids ◽  
Pure Hydrocarbon

The syntheses of palmitic acids and a nonadecane are reported with CF2 groups located 1,3 or 1,4 to each other along the aliphatic chain. Specifically 8,8,10,10- and 8,8,11,11-tetrafluorohexadecanoic acids (6b and 6c) are prepared as well as the singly modified analogue 8,8-difluorohexadecanoic acid (6a). Also 8,8,11,11-tetrafluorononadecane (27) is prepared as a pure hydrocarbon containing a 1,4-di-CF2 motif. The modified palmitic acids are characterized by differential scanning calorimetry (DSC) to determine melting points and phase behaviour relative to palmitic acid (62.5 °C). It emerges that 6c, with the CF2 groups placed 1,4- to each other, has a significantly higher melting point (89.9 °C) when compared to the other analogues and palmitic acid itself. It is a crystalline compound and the structure reveals an extended anti-zig-zag chain. Similarly 8,8,11,11-tetrafluorononadecane (27) adopts an extended anti-zig-zag structure. This is rationalized by dipolar relaxation between the two CF2 groups placed 1,4 to each other in the extended anti-zig-zag chain and suggests a design modification for long chain aliphatics which can introduce conformational stability.

Development and Characterization of Bismaleimides Containing Aliphatic Chain for Microelectronics Application

e-Polymers ◽  
2006 ◽  
Vol 6 (1) ◽  
Author(s):  
J. L. Feng ◽  
C. Y. Yue ◽  
K. S. Chian
Keyword(s):  
Chain Length ◽  
Moisture Absorption ◽  
Thermomechanical Analysis ◽  
Stress And Strain ◽  
Aliphatic Chain ◽  
Melting Points ◽  
Scanning Calorimetry ◽  
Backbone Chain ◽  
Gel Temperature

AbstractA series of bismaleimide systems containing aliphatic backbone chain have been synthesized and investigated. Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Thermomechanical analysis (TMA), rheometry and tensile test were used to characterize the thermal and mechanical properties. It was noted that backbone chain length and odd-even effect affected properties. As the chain length increases, the curing peak temperature, gel temperature of BMI all increase, but the melting point, glass transition and moisture absorption decrease. The melting points of BMI-3,5,7 reduced most significantly. The tensile properties were affected by odd even effect significantly. BMI-3,5,7 with odd number of carbons have less stress and strain than those of even ones.

Phase Behaviour and FTIR Spectra of Ionic Liquids: The Mixtures of 1-Butyl-1-methylpyrrolidinium Chloride and TaCl5

2008 ◽  
Vol 63 (1-2) ◽  
pp. 66-72 ◽  
Author(s):  
Olga B Babushkina
Keyword(s):  
Thermal Stability ◽  
Ionic Liquids ◽  
Ftir Spectra ◽  
Phase Behaviour ◽  
Molar Ratio ◽  
Ionic Interactions ◽  
Melting Points ◽  
Scanning Calorimetry ◽  
Molar Ratios ◽  
Insight Into

A series of ionic liquids consisting of 1-butyl-1-methylpyrrolidinium chloride (Pyr14Cl) and TaCl5 at molar ratios of Pyr14Cl in the range of 0.85 - 0.20 was synthesized. They exhibit potential application as electrolytes for the electrochemical deposition of tantalum. The thermal behaviour of the Pyr14Cl-TaCl5 mixtures was investigated, using differential scanning calorimetry (DSC) to estimate the range of thermal stability and to determine the optimal compositions for electrochemical trials. The Pyr14Cl-TaCl5 mixtures formed stoichiometric 3 : 2 and 2 : 3 crystalline phases with melting points of 70 °C and 130 °C, respectively, characterized by entropies of fusion of 13.6 JK−1 mol−1 and 10.1 JK−1 mol−1. The mixtures with molar fractions of Pyr14Cl equal to 0.60 and 0.40 were clear and transparent liquids and had the lowest viscosity; they were the most suitable for electrochemical applications. FTIR spectra of the Pyr14Cl-TaCl5 mixtures allowed to get insight into inter-ionic interactions and the nature of formation of these ionic liquids as a function of the molar ratio of the components.

scholarly journals Double-Chain Cationic Surfactants: Swelling, Structure, Phase Transitions and Additive Effects

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3946
Author(s):  
Rui A. Gonçalves ◽  
Yeng-Ming Lam ◽  
Björn Lindman
Keyword(s):  
Phase Transitions ◽  
Phase Behaviour ◽  
Double Chain ◽  
Scanning Calorimetry ◽  
Alkyl Chains ◽  
X Ray Scattering ◽  
Amphiphilic Compounds ◽  
Liquid Phases ◽  
Lamellar Phases ◽  
Water Layers

Double-chain amphiphilic compounds, including surfactants and lipids, have broad significance in applications like personal care and biology. A study on the phase structures and their transitions focusing on dioctadecyldimethylammonium chloride (DODAC), used inter alia in hair conditioners, is presented. The phase behaviour is dominated by two bilayer lamellar phases, Lβ and Lα, with “solid” and “melted” alkyl chains, respectively. In particular, the study is focused on the effect of additives of different polarity on the phase transitions and structures. The main techniques used for investigation were differential scanning calorimetry (DSC) and small- and wide-angle X-ray scattering (SAXS and WAXS). From the WAXS reflections, the distance between the alkyl chains in the bilayers was obtained, and from SAXS, the thicknesses of the surfactant and water layers. The Lα phase was found to have a bilayer structure, generally found for most surfactants; a Lβ phase made up of bilayers with considerable chain tilting and interdigitation was also identified. Depending mainly on the polarity of the additives, their effects on the phase stabilities and structure vary. Compounds like urea have no significant effect, while fatty acids and fatty alcohols have significant effects, but which are quite different depending on the nonpolar part. In most cases, Lβ and Lα phases exist over wide composition ranges; certain additives induce transitions to other phases, which include cubic, reversed hexagonal liquid crystals and bicontinuous liquid phases. For a system containing additives, which induce a significant lowering of the Lβ–Lα transition, we identified the possibility of a triggered phase transition via dilution with water.

scholarly journals Phase Behaviour of Methane Hydrates in Confined Media

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 201
Author(s):  
Hao Bian ◽  
Lu Ai ◽  
Klaus Hellgardt ◽  
Geoffrey C. Maitland ◽  
Jerry Y. Y. Heng
Keyword(s):  
Phase Behaviour ◽  
Methane Hydrates ◽  
Scanning Calorimetry ◽  
Macroporous Silica ◽  
Interfacial Energies ◽  
Temperature Method ◽  
Hydrate Phase ◽  
Dissociation Temperature ◽  
Confined Media ◽  
Decomposition Behaviour

In a study designed to investigate the melting behaviour of natural gas hydrates which are usually formed in porous mineral sediments rather than in bulk, hydrate phase equilibria for binary methane and water mixtures were studied using high-pressure differential scanning calorimetry in mesoporous and macroporous silica particles having controlled pore sizes ranging from 8.5 nm to 195.7 nm. A dynamic oscillating temperature method was used to form methane hydrates reproducibly and then determine their decomposition behaviour—melting points and enthalpies of melting. Significant decreases in dissociation temperature were observed as the pore size decreased (over 6 K for 8.5 nm pores). This behaviour is consistent with the Gibbs–Thomson equation, which was used to determine hydrate–water interfacial energies. The melting data up to 50 MPa indicated a strong, essentially logarithmic, dependence on pressure, which here has been ascribed to the pressure dependence of the interfacial energy in the confined media. An empirical modification of the Gibbs–Thomson equation is proposed to include this effect.

Water Effect on Solubilities of Lauric and Palmitic Acids in Ethanol and 2-Propanol Determined by Differential Scanning Calorimetry

2021 ◽  
Author(s):  
Grazielle Oliveira ◽  
Andrea Briones Gonçalves Bonassoli ◽  
Marlus Pinheiro Rolemberg ◽  
Marilsa Aparecida Mota ◽  
Rodrigo Correa Basso ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Water Effect ◽  
Scanning Calorimetry ◽  
Palmitic Acids

scholarly journals Stacking Control by Molecular Symmetry of Sterically Protected Phthalocyanines

Molecules ◽  
2020 ◽  
Vol 25 (23) ◽  
pp. 5552
Author(s):  
Ryota Kudo ◽  
Masahiro Sonobe ◽  
Yoshiaki Chino ◽  
Yu Kitazawa ◽  
Mutsumi Kimura
Keyword(s):  
Lamellar Structure ◽  
Synthesis And Characterization ◽  
Molecular Symmetry ◽  
X Ray Diffraction ◽  
Melting Points ◽  
Scanning Calorimetry ◽  
Structural Isomers ◽  
X Ray ◽  
Temperature Controlled

The synthesis and characterization of two phthalocyanine (Pc) structural isomers, 1 and 2, in which four 2,6-di(hexyloxy)phenyl units were attached directly to the 1,8,15,22- or 1,4,15,18-positions of the Pc rings, are described. Both Pcs 1 and 2 exhibited low melting points, i.e., 120 and 130 °C respectively, due to the reduction in intermolecular π-π interaction among the Pc rings caused by the steric hindrance of 2,6-dihexyloxybenzene units. The thermal behaviors were investigated with temperature-controlled polarizing optical microscopy, differential scanning calorimetry, powder X-ray diffraction, and absorption spectral analyses. Pc 1, having C4h molecular symmetry, organized into a lamellar structure containing lateral assemblies of Pc rings. In contrast, the other Pc 2 revealed the formation of metastable crystalline phases, including disordered stacks of Pcs due to rapid cooling from a melted liquid.

Crystallization Behavior of Polyethylene/Montmorillonite Nanocomposites Prepared by In Situ Polymerization

2012 ◽  
Vol 184-185 ◽  
pp. 932-935
Author(s):  
Min Li ◽  
Li Guang Xiao ◽  
Hong Kai Zhao
Keyword(s):  
Differential Scanning Calorimetry ◽  
Crystallization Behavior ◽  
Crystallization Process ◽  
In Situ Polymerization ◽  
Nucleating Agent ◽  
Lower Content ◽  
Melting Points ◽  
Scanning Calorimetry ◽  
Montmorillonite Nanocomposites

Polyethylene/montmorillonite (PE/MMT) nanocomposites were prepared by in situ polymerization. The crystallization behavior of PE/MMT nanocomposites at different MMT concentrations (from 0.1 to 1.2 wt %) were investigated by differential scanning calorimetry (DSC). The equilibrium melting points increase by the addition of MMT. The crystallization rates of PE/MMT nanocomposites are faster than those of pure PE. The addition of MMT facilitated the crystallization of PE, with the MMT functioning as a heterogeneous nucleating agent at lower content; at higher concentrations, however, the physical hindrance of the MMT layers to the motion of PE chains retarded the crystallization process.

Two New Thermotropic Liquid Crystalline Polyesters and their Composites: Synthesis and Characterization

2009 ◽  
Vol 87-88 ◽  
pp. 154-159
Author(s):  
Chuan Ji Zhang ◽  
Zhi Xiong Huang ◽  
Min Xian Shi ◽  
Ming Zhang
Keyword(s):  
Mechanical Properties ◽  
Liquid Crystalline ◽  
Synthesis Process ◽  
Differential Scanning Calorimetric ◽  
Melting Points ◽  
Texture Characteristic ◽  
Scanning Calorimetry ◽  
Heating And Cooling ◽  
Melt Polycondensation ◽  
Monomer Structure

Two new series of liquid crystalline polyesters were synthesized using melt polycondensation reaction.Glass fiber,as a reinforcement,was meltpolymerized with 4-acetoxybenzoic(ABA),4,4＇-diacetoxybiphenyl, isophthalic acid(IA) and terephthalic acid(TA) to make TLCP/GF composites with a good mechanical properties.All the obtained compounds were characterized by conventional spectroscopic methods. The structure of the target compounds and intermediates was conformed by the IR, 1H NMR and SEM. The thermal behavior of the polymers has been characterized using polarized optical microscopy and differential scanning calorimetry. The effect of monomer structure and mechanical properties has been investigated on the prepared polyesters. These compounds show a high birefringent Schlierene texture characteristic of the nematic phase on heating and cooling experiments. This was further confirmed using differential scanning calorimetric investigations.The melting points of polymers having a central 4,4’-biphenyldicarboxylate residue have broad endotherms. The glass transition temperature values of polyesters are not effect by the glass fiber.According to the SEM result showed that the composite had strong fiber-matrix adhesion.The effect of copolymerization with added glass fiber in synthesis process is compared with that of the anlogous homopolyesters by other processing mode.Our finding shows that the copolymers exhibit reduced technical process and maintained mechanical properties.

SAXS Study of Selected Cationic Surfactant Influence on the DSPC-Based Model Phospholipid System

2007 ◽  
Vol 130 ◽  
pp. 257-262
Author(s):  
Maciej Kozak ◽  
Ludwik Domka ◽  
Stefan Jurga
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Small Angle ◽  
Phase Behaviour ◽  
Lamellar Phase ◽  
Scanning Calorimetry ◽  
X Ray ◽  
X Ray Scattering ◽  
Hydrocarbon Chains ◽  
Main Transition

The phase behaviour of lipid bilayer systems prepared with 1,2-distearoyl-sn-glycero-3- phosphocholine (DSPC) with dodecyldimethyl(benzyloxymethyl)ammonium chloride (BzMDDAC) (at concentrations 0.1, 1 and 5%) has been studied by small angle X-ray scattering and differential scanning calorimetry. The SAXS and DSC results of the hydrated 10% DSPC revealed one typical phase transition corresponding to melting of the hydrocarbon chains at 55 °C. In the system of 10% DSPC - 0.1 % BzMDDAC the main transition was somewhat shifted towards lower temperatures, while at 1% concentration of BzMDDAC in the mixture, the lamellar phase disappeared, as evidenced by SAXS and DSC. The increase in BzMDDAC concentration to 5% in the mixture with 10% DSPC resulted in formation of a new lamellar phase.

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