The role of the symmetry and the flexibility of the anion on the characteristics of the nanostructures and the viscosities of ionic liquids☆

The transport properties of ionic liquids (ILs) are crucial properties in view of their applications in electrochem-ical devices. One of the most important advantages of ILs is that their chemical–physical properties and conse-quently their bulk performances can be well tuned by optimizing the chemical structures of their ions. This will require elucidating the structural features of the ions that fundamentally determine the characteristics of the nanostructures and the viscosities of ILs. Here we showed for the first time that the“rigidity”, the order, and the compactness of the three-dimensional ionic networks generated by the anions and the cation head groups determine the formation and the sizes of the nanostructures in the apolar domains of ILs. We also found that the properties of ionic networks are governed by the conformational flexibility and the symmetry of the anion and/or the cation head group. The thermal stability of the nanostructures of ILs was shown to be con-trolled by the sensitivity of the conformational equilibrium of the anion to the change of temperature. We showed that the viscosity of ILs is strongly related to the symmetry and the flexibility of the constitute ions rather than to the size of the nanostructures of ILs. Therefore, the characteristics of the nanostructures and the viscosities of ILs, especially the thermal stability of the nanostructures, can be fine-tuned by tailoring the symmetry and the conformational flexibility of the anion.     

Adhere to the principle of “Science and technology is the No. 1 productive force”, strive for the realization of the strategic target of“Boosting chemical industry by science and technology”

In this pen conference, we have invited authorities and experts concerned to further elaborate the connotations and significance of the principle of "Science and technology is the No. 1 productive force" , discuss the problems encountered in implementing the principle in chemical industry and measures consequently taken against them and exchange experience gained in executing the policy of "Boosting chemical industry by science and technology" , The purpose is to accelerate the modernization process of China's chemical industry and realize the strategic target set by the government.     

16 Rubber Companies Became Pilot Companies for the Integration of “Informationization and Industrialization” of the State

正On August 26,at the conference of advancing implementation of the standard for management system of the integration of"Informationization and Industrialization"of the state,the Ministry of Industry and Information Technology released the 2017 list of model     

Market Status and Development of Cannabis Aativa Cosmetics in the Times of “Secondary-Constituent Community”

Since 2020,with the advent of the COVID-19 epidemic,the upsurge of the concept of“Constituent community”in the cosmetics industry has gradually subsided.The phenomenon of only focuing on the components but not on the synergies of the product system has gradually ebbed.On the other hand,with the popularity of the concept of industrial Cannabis sativa and Cannabis sativa cosmetics both at home and abroad,the Cannabis sativa cosmetics that replace the single effect propaganda of the Constituent community have been increasingly recognized by consumers,and industrial Cannabis sativa is increasingly widely used in cosmetics.For the development of Cannabis sativa cosmetics in the times of“Secondary-Constituent community”,the market status of Cannabis sativa cosmetics in China and abroad was analyzed in this paper.At the same time,the future development prospect of domestic Cannabis sativa cosmetics was preliminarily estimated and prospected,which was helpful for the development of Cannabis sativa cosmetics and provided the evaluation basis for the investment and development of domestic Cannabis sativa cosmetics.     

On the results of the First All-Russian Conference “Sol-Gel Synthesis and Study of Inorganic Compounds,Hybrid Functional Materials,and Disperse Systems”

Chronicle

On the results of the First All-Russian Conference “Sol-Gel Synthesis and Study of Inorganic Compounds, Hybrid Functional Materials, and Disperse Systems”     

On the problem of the “effective” secondary nuclei

Introducing an “on-line” Coulter Counter measurement technique in a stirred fluidized bed of KAl(SO₄)₂·12H₂O crystals in order to observe the generated secondary nuclei leads to results. But even these results still do not give an answer to the complicated phenomena of birth and growth of the secondary nuclei.The results are the following:Secondary nuclei of sizes smaller than 2 μm are generated and the smaller the size the higher the number of the generated nuclei.Nuclei below about 3 μm seem not to be “effective”. The high number of particles in the unfiltered “pure” solution prior to the experiment does not grow in the sampling cells. The number of nuclei grown in the sampling cells corresponds to the number of nuclei above 3 μm counted by the Coulter Counter. There are particles growing more slowly in the sampling cells, but the number is much smaller than the number of particles below 3 μm counted by the Coulter Counter. This means some of these particles do not grow or they grow at very slow rates or something else happens to them.The higher the supersaturation the more nuclei are generated. The effect of supersaturation at high stirrer speeds is the least with the small nuclei, but the strongest with the larger nuclei sizes. That means more nuclei can be found in larger size ranges at high supersaturations and high stirrer speeds.The higher the stirrer speed the more nuclei are generated.The power number found for the supersaturation 1.3 fits well into the range of 1.3–1.6 given by former work.     

Synthesis and Characterization of the Inclusion Complex of β-cyclodextrin and Azomethine

A β-cyclodextrin (β-Cyd) inclusion complex containing azomethine as a guest was prepared by kneading method with aliquot addition of ethanol. The product was characterized by Fourier Transform Infrared (FTIR) spectrometer, ¹H Nuclear Magnetic Resonance (¹H NMR) and Thermogravimetric Analyzer (TGA), which proves the formation of the inclusion complex where the benzyl part of azomethine has been encapsulated by the hydrophobic cavity of β-Cyd. The interaction of β-Cyd and azomethine was also analyzed by means of spectrometry by UV-Vis spectrophotometer to determine the formation constant. The formation constant was calculated by using a modified Benesi-Hildebrand equation at 25 °C. The apparent formation constant obtained was 1.29 × 10⁴ L/mol. Besides that, the stoichiometry ratio was also determined to be 1:1 for the inclusion complex of β-Cyd with azomethine.     

“Roughness” of the Gasless Combustion Front

Concepts of local curvatures of the combustion front (roughnesses) caused by penetration of the melt into the heating zone are developed. Based on the estimates of characteristic times and scales of individual stages, different combustion modes and their relation with the structural parameters of the initial mixture are revealed.     

Development and characterization of a “store and create” microfluidic device to determine the heterogeneous freezing properties of ice nucleating particles

Abstract

Understanding heterogeneous ice nucleation induced by ice nucleating particles (INPs) is hindered by analytical challenges in accurately determining the freezing temperature spectrum, abundance, and physicochemical properties of INPs. Here we evaluate the performance of a microfluidic device that employs a “store and create” approach to measure the ice nucleation properties of approximately 600 uniformly sized nanoliter water droplets. These droplets are immersed in surfactant-free environmentally sustainable squalene oil and do not contact the polymer walls of the microfluidic device. The device interfaced with a cold plate temperature controller has a greatly reduced background freezing temperature spectrum for filtered water droplets compared to conventional microliter droplet-on-substrate freezing methods. Droplets containing particles of interest are readily generated on-chip from a suspension of particles in water. Background freezing for 6 nL water droplets exhibits a median freezing temperature of ?33.7?±?0.4?°C, close to the theoretical freezing temperature of ?34.5?°C. The immersion freezing temperature spectra obtained from Snomax bacterial and illite mineral particles compares well with literature data, and the freezing contribution from either type of particle can be separated from a mixed suspension. Our approach generates a highly uniform droplet size distribution, causes no clogging of the microfluidic device, and is capable of reproducible droplet refreezes. The high-resolution freezing spectra obtained from large droplet number arrays enables the use of the derivative INP temperature spectrum analysis to quantitatively distinguish between different classes of INPs. The lower and consistent filtered water background freezing temperature enables measurements of almost the entire immersion freezing temperature regime from ?33 to 0?°C, and quantification of weaker but often abundant INPs such as those found in biomass-burning smoke aerosol.

Copyright © 2019 American Association for Aerosol Research     

Insight into the synthesis and thermomechanical properties of “short-long” type biobased aliphatic polyesters

A series of biobased “short-long” chain aliphatic polyesters having high molecular weight were successfully synthesized using dimethyl sebacate and diols with different carbon chain lengths via a two-step melt-polycondensation method by using titanium butoxide as a catalyst. The diols chain length and its odd-even effect on the structure–property relationship, crystallinity, and thermomechanical properties of the polyesters were systemically investigated. The synthesized polyesters displayed weight-average molecular weight between 23,600 to 72,900 g/mol and a maximum intrinsic viscosity of 0.933 dL/g. With increasing the diol chain length, the molecular weight of the polyesters increased linearly, except for poly(butylene sebacate) (PBS). Altogether, the “odd-even” effect of the diol chain on the crystalline (T_c)/melting temperature (T_m), and melting/ crystallization enthalpies of the polyester's were observed. Poly(pentylene sebacate) (PPeS) has the highest weight-average molecular weight of 72,900 Da, T_m of ∼55.4°C, degradation temperature (T_d,max) of about 404°C, and highest storage modulus (E′ at 25°C) of 661 MPa compared to other short-chain polyesters. PBS and PPeS showed the appearance of sharp intensity peaks from XRD diffraction patterns, indicating higher crystallinity in the material, in accordance with crystallization enthalpies (ΔH_c) values from the differential scanning calorimetry (DSC) thermograms. These fabricated biobased polymers with 100% bio-content, low melting temperature range, rapid crystallization, and high thermal stability suggest good processability and can offer an alternative option to nonrenewable thermoplastic polyesters for potential applications.     

Synthesis and crystal structure of the first “carbons apart” diamagnetic lutetiacarborane sandwich complex

The reaction of closo-exo-5,6-Na(THF)₂-1-Na(THF)₂-2,4-(SiMe₃)₂-2,4-C₂B₄H₄ (1) and anhydrous LuCl₃, in a molar ratio of 2:1, in dry benzene at 60 °C produced the first full-sandwiched lutetiacarborane complex, 2,2^′,4,4^′-(SiMe₃)₄-3,5^′,6^′-[(μ-H)₃Na(THF)₂]-1,1^′-commo-Lu(η⁵-2,4-C₂B₄H₄)₂ (2), as an off-white crystalline solid in 88% yield.     

Investigation of the effect of minor ions on the stability of β-C2S and the mechanism of stabilization

In this paper the effect of minor ions on the stability of β-C₂S has been studied. It is discovered that the effect of minor ions on the stability of β-C₂S is closely related to the polarization ability of the ions. According to this the authors propose a new judgement, the ion polarization ability judgement, by which we can determine if minor ions have the stabilizing affect on β-C₂S. The judgement is that those ions, either having smaller polarization ability than that of calcium ion or greater than that of silicon ion, all have the ability to effect the stability of β-C₂S. This judgement is more practical than those made by other authors. In this paper a new mechanism about the stabilization has been described on the basis of applying the principles of thermodynamics and dynamics of the transformation of solid phases in accordance with the above judgement.