Development of an Integrated Framework for Multiscale,Multiphase Modeling of Industrial Slurry‐Phase Reactors for Polyethylene Production

A framework based on the Monte Carlo/random‐pore polymeric flow model is proposed to simulate both single‐particle and continuous slurry reactor industrial polymerizations. The Sanchez–Lacombe equation of state describes the distributions of components in the different phases of these systems. The developed process model is applied to describe heterogeneously catalyzed polymerizations of ethylene in n‐hexane diluent with or without 1‐hexene as a comonomer, but the proposed methodology is applicable to any ethylene/1‐olefin copolymerization in slurry reactors. In addition to the effects of catalyst particle size and reactor residence time distributions, the proposed hybrid model is used to investigate the impact of several catalyst characteristics under different process conditions on polymer yield and microstructure. Particular attention is paid to the catalyst fragmentation process and active center distribution through the particle. These simulations demonstrate the versatility and thoroughness of combining Monte Carlo simulation with single‐particle models to analyze and predict the behavior of commercial polyolefin reactors.     

Molecular weight dependence of phase behavior of PEO/P(EO‐b‐DMS) blends: Application of Sanchez‐Lacombe lattice fluid theory

Molecular weight dependence of phase separation behavior of the Poly (ethylene oxide) (PEO)/Poly(ethylene oxide‐block‐dimethylsiloxane) (P(EO‐b‐DMS)) blends was investigated by both experimental and theoretical methods. The cloud point curves of PEO/P(EO‐b‐DMS) blends were obtained by turbidity method. Based on Sanchez‐Lacombe lattice fluid theory (SLLFT), the adjustable parameter, (quantifying the interaction energy between different components), was evaluated by fitting the experimental data in phase diagrams. To calculate the spinodals, binodals, and the volume changes of mixing for these blends, three modified combining rules of the scaling parameters for the block copolymer were introduced. The calculated binodals with those modified combining rules show good agreement with the experimental data. Furthermore, the calculated volume changes during mixing decrease with increasing molecular weight of PEO, and the relationship between the volume changes and temperature is quite different for the mixtures with different molecular weight of PEO. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 452–459, 2008     

Measurement and prediction of solubilities and diffusion coefficients of carbon dioxide in starch–water mixtures at elevated pressures

The solubility and diffusion coefficient of carbon dioxide in intermediate‐moisture starch–water mixtures were determined both experimentally and theoretically at elevated pressures up to 16 MPa at 50 °C. A high‐pressure decay sorption system was assembled to measure the equilibrium CO₂ mass uptake by the starch–water system. The experimentally measured solubilities accounted for the estimated swollen volume by Sanchez–Lacombe equation of state (S‐L EOS) were found to increase almost linearly with pressure, yielding 4.0 g CO₂/g starch–water system at 16 MPa. Moreover, CO₂ solubilities above 5 MPa displayed a solubility increase, which was not contributed by the water fraction in the starch–water mixture. The solubilities, however, showed no dependence on the degree of gelatinization (DG) of starch. The diffusion coefficient of CO₂ was found to increase with concentration of dissolved CO₂, which is pressure‐dependent, and decrease with increasing DG in the range of 50–100%. A free‐volume‐based diffusion model proposed by Areerat was employed to predict the CO₂ diffusivity in terms of pressure, temperature, and the concentration of dissolved CO₂. S‐L EOS was once more used to determine the specific free volume of the mixture system. The predicted diffusion coefficients showed to correlate well with the measured values for all starch–water mixtures. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 607–621, 2006     

13Carbon nuclear magnetic resonance of ethylene–propylene–1‐hexene terpolymers

We report the complete ¹³C NMR characterization of a series of ethylene–propylene–1‐hexene terpolymers obtained with the metallocenic system rac‐ethylene bis‐indenyl zirconium dichloride, with different comonomer ratios. A detailed study of ¹³C NMR chemical shifts, triad sequence distributions, monomer‐average sequence lengths, and reactivity ratios for these terpolymers is presented. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2474–2482, 2004     

Characterization of chemical constituents in Zhi–Zi–Da–Huang decoction by ultra high performance liquid chromatography coupled with quadrupole time‐of‐flight mass spectrometry

A sensitive and reliable ultra high performance liquid chromatography coupled with quadrupole time‐of‐flight mass spectrometry method was established to separate and identify the chemical constituents of Zhi–Zi–Da–Huang decoction, a classic traditional Chinese medicine formula. The chromatographic separation was achieved on a Shim‐pack XR‐ODS C₁₈ column (75  × 3.0 mm, 2.2 μm) using a gradient elution program. The detection was performed on a Waters Xevo G2 Q‐TOF mass spectrometer equipped with electrospray ionization source in both positive and negative modes. With the optimized conditions, a total of 82 compounds were identified or tentatively characterized. Of the 82 compounds, 21 compounds were identified by comparing the retention time and MS data with reference standards, the rest were characterized by analyzing MS data and retrieving the reference literature. In addition, 31 compounds were identified from Gardenia jasminoides Ellis, ten compounds were identified from Rheum palmatum L., 33 compounds were identified from Citrus aurantium L., and eight compounds were identified from Sojae Semen Praeparatum. Results indicated that iridoids, anthraquinones, flavonoids, isoflavonoids, coumarins, glycosides of crocetin, monoterpenoids, and organic acids were major constituents in Zhi–Zi–Da–Huang decoction. It is concluded that the developed ultra high performance liquid chromatography coupled with quadrupole time‐of‐flight mass spectrometry method with high sensitivity and resolution is suitable for identifying and characterizing the chemical constituents of Zhi–Zi–Da–Huang decoction, and the analysis provides a helpful chemical basis for further research on Zhi–Zi–Da–Huang decoction.     

Solution and Solid‐State Studies on the Halide Binding Affinity of Perfluorophenyl‐Armed Uranyl–Salophen Receptors Enhanced by Anion–π Interactions

The enhancement of the binding between halide anions and a Lewis acidic uranyl–salophen receptor has been achieved by the introduction of pendant electron‐deficient arene units into the receptor skeleton. The association and the occurrence of the elusive anion–π interaction with halide anions (as tetrabutylammonium salts) have been demonstrated in solution and in the solid state, providing unambiguous evidence on the interplay of the concerted interactions responsible for the anion binding.     

Spatially Controlled Out‐of‐Equilibrium Host–Guest System under Electrochemical Control

Self‐assembly to create molecular and nanostructures is typically performed at the thermodynamic minimum. To achieve dynamic functionalities, such as adaptability, internal feedback, and self‐replication, there is a growing focus on out‐of‐equilibrium systems. This report presents the dynamic self‐assembly of an artificial host–guest system at an interface, under control by a dissipative electrochemical process using (electrical) energy, resulting in an out‐of‐equilibrium system exhibiting a supramolecular surface gradient. The gradient, its steepness, rate of formation, and complex surface composition after backfilling, as well as the surface compositions after switching between the different states of the system, are assessed and supported by modelling. Our method shows for the first time an artificial surface‐confined out‐of‐equilibrium system. The electrochemical process parameters provide not only control over the system in time, but also in space.     

Pressure–Volume–Temperature properties of polyolefin liquids and their melt miscibility

The pressure–volume–temperature (P–V–T) properties of a number of metallocene-produced polyolefins were measured experimentally at 10 MPa ≤ P ≤ 200 MPa and 30°C ≤ T ≤ 220°C in a dilatometer-type P–V–T apparatus. These included ethylene copolymers typical of linear low density polyethylene, with several α-olefins as comonomers and a wide range of comonomer content. The experimental P–V–T data were correlated with the equations of state from the Sanchez–Lacombe and Flory–Orwoll–Vrij theories. The solubility parameter map of the polyolefins, at atmospheric pressure, was established on the basis of the thermodynamic data. As the temperature increases, the solubility parameter of the polyolefin decreases. The solubility parameters of copolymers of ethylene with propylene, butene, hexene, and octene under constant temperature are all more or less the same at equal weight percent of comonomer. As the incorporation of branches increases, the solubility parameter decreases. The melt miscibility of the polyolefin blends can be predicted to design various blend products for specific applications from this solubility parameter map. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2835–2844, 1999     

Enantioselective Synthesis of β‐Iodo Morita–Baylis–Hillman Esters by a Catalytic Asymmetric Three‐Component Coupling Reaction

A catalytic route toward chiral Morita–Baylis–Hillman esters by asymmetric coupling between α,β‐acetylenic esters, aldehydes, and trimethylsilyl iodide has been developed (see scheme). The reaction proceeds with high to excellent enantioselectivities, and the products can be transformed into β‐branched derivatives in a single step and with excellent retention of configuration. TMS=trimethylsilyl

     

Solid‐State Structural Characterization of Cutinase–ECE‐Pincer–Metal Hybrids

Crystal‐clear structures : The first crystal structures of organometallic pincer–cutinase hybrids (see figure) provide insight into the 3D structural arrangement of both the protein and the organometallic pincer moiety, and reveal different binding modes for different pincers.

     

Multi‐component profiles through the blood–brain barrier in rat after oral administration of over‐the‐counter drug Keke capsule by ultra‐performance liquid chromatography/quadrupole‐ time‐of‐flight MSE method

Keke capsule as a traditional Chinese medicine formulation is used to relieve cough, for analgesia and to reduce bronchial asthma. The multi‐components are absorbed into the blood and brain after oral administration of Keke capsule, with no systematic investigation so far. A reliable and rapid UPLC–QTOF–MS^E combined with a data processing software platform was used to characterize the components of Keke capsule and simultaneously identify bioactive components in blood and brain tissues in rat after oral administration. Consequently, a total of 41 components of Keke capsule, including alkaloids, flavone, flavonols, triterpene, lignanoid, organic acids, glycosides and coumarin were identified. Twenty‐one components were found in plasma, including 18 prototypes and three metabolites; 15 components were found in brain tissues, including 10 prototypes and five metabolites. Alkaloids and flavonoids in Keke capsule were the main components which were absorbed into blood. The main alkaloids of Keke capsule can pass through the blood–brain barrier and show different distribution tendencies in brain tissues. The main components of keke capsule was simultaneously analyzed by throughput analysis, and the corresponding bioactive components were examined by blood‐brain barrier in the rat after oral administration of the capsule.     

Versatile Self‐Complexing Compounds Based on Covalently Linked Donor–Acceptor Cyclophanes

A range of covalently linked donor–acceptor compounds which contain 1) a hydroquinone (HQ) unit, 2) a 1,5‐dioxynaphthalene (DNP) ring system, or 3) a tetrathiafulvalene (TTF) unit as the π‐donor, and 4) cyclobis(paraquat‐p‐phenylene) (CBPQT⁴⁺) as the π‐accepting tetracationic cyclophane were prepared and shown to operate as simple molecular machines. The π‐donating arms can be included inside the cyclophane in an intramolecular fashion by virtue of stabilizing noncovalent bonding interactions. What amounts to self‐complexing/decomplexing equilibria were shown to be highly temperature dependent when the π‐donating arm contains either an HQ or DNP moiety. The thermodynamic parameters associated with the equilibria have been unraveled by using variable‐temperature ¹H NMR spectroscopy. The negative ΔH° and ΔS° values account for the fact that the “uncomplexed” conformation becomes the dominant species, since the entropy gain associated with the decomplexation process overcomes the enthalpy loss resulting from the breaking of the donor–acceptor interactions. The arm's in‐and‐out movements with respect to the linked cyclophanes can be arrested by installing a bulky substituent at the end of the arm. In the case of compounds carrying a DNP ring system in their side arm, two diastereoisomeric, self‐complexing conformations are observed below 272 K in hexadeuterioacetone. By contrast, control over the TTF‐containing arm's movement is more or less ineffective through the thermally sensitive equilibrium although it can be realized by chemical and electrochemical ways as a result of TTF's excellent redox properties. Such self‐complexing compounds could find applications as thermo‐ and electroswitches. In addition, the thermochromism associated with the arm's movement could lead to some of the compounds finding uses as imaging and sensing materials.     

A Stable Quasi‐Solid‐State Sodium–Sulfur Battery

Ambient‐temperature sodium–sulfur (Na–S) batteries are considered a promising energy storage system due to their high theoretical energy density and low costs. However, great challenges remain in achieving a high rechargeable capacity and long cycle life. Herein we report a stable quasi‐solid‐state Na‐S battery enabled by a poly(S‐pentaerythritol tetraacrylate (PETEA))‐based cathode and a (PETEA‐tris[2‐(acryloyloxy)ethyl] isocyanurate (THEICTA))‐based gel polymer electrolyte. The polymeric sulfur electrode strongly anchors sulfur through chemical binding and inhibits the shuttle effect. Meanwhile, the in situ formed polymer electrolyte with high ionic conductivity and enhanced safety successfully stabilizes the Na anode/electrolyte interface, and simultaneously immobilizes soluble Na polysulfides. The as‐developed quasi‐solid‐state Na‐S cells exhibit a high reversible capacity of 877 mA h g^?1 at 0.1 C and an extended cycling stability.     

Effect of nitrogen on mechanical,oxidation and structural behaviour of Ti–Si–B–C–N nanocomposite hard coatings deposited by DC sputtering

Ti–Si–B–C–N film was deposited by DC magnetron sputtering at different argon and nitrogen ratios such as N₂/Ar = 1 : 5, 2 : 4, 3 : 3, 4 : 1 and 5 : 0. The formation of TiN and TiB phases was observed because of incorporation of nitrogen. The hardness, modulus, microstructure, structure and bond formation with different nitrogen contents during the deposition were studied by nanoindentation, scanning electron microscope, X‐ray diffraction and X‐ray photoelectron spectroscopy, respectively. The oxidation kinetics of Ti–Si–B–C–N was investigated. The nitrogen incorporation during deposition influences different properties of the coating. Hardness and modulus decreased, and microstructure showed very fine grain presence, and film changes to fully amorphous because of incorporation of nitrogen in the film. Copyright © 2016 John Wiley & Sons, Ltd.     

Alternating,gradient, block,and block–gradient copolymers of ethylene and norbornene by Pd–Diimine‐Catalyzed “living” copolymerization

We demonstrate, in this article, the facile synthesis of a broad class of low‐polydispersity ethylene–norbornene (E–NB) copolymers having various controllable comonomer composition distributions, including gradient, alternating, diblock, triblock, and block–gradient, through “living”/quasiliving E–NB copolymerization facilitated with a single Pd – diimine catalyst ( 1 ). This synthesis benefits from two remarkable features of catalyst 1 , its high capability in NB incorporation and high versatility in rendering E–NB “living” copolymerization at various NB feed concentrations ([NB]₀) while under an ethylene pressure of 1 atm and at 15 °C. At higher [NB]₀ values between 0.42 and 0.64 M, E–NB copolymerization with 1 renders nearly perfect alternating copolymers. At lower [NB]₀ values (0.11–0.22 M), gradient copolymers yield due to gradual reduction in NB concentration, with the starting chain end containing primarily alternating segments and the finishing end being hyperbranched polyethylene segments. Through two‐stage or three‐stage “living” copolymerization with sequential NB feeding, diblock or triblock copolymers containing gradient block(s) have been designed. This work thus greatly expands the family of E–NB copolymers. All the copolymers have controllable molecular weight and relatively low polydispersity (with polydispersity index below 1.20). Most notably, some of the gradient and block–gradient copolymers have been found to exhibit the characteristic broad glass transitions as a result of their possession of broad composition distribution. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Vapor‐Phase Deposition and Modification of Metal–Organic Frameworks: State‐of‐the‐Art and Future Directions

Materials processing, and thin‐film deposition in particular, is decisive in the implementation of functional materials in industry and real‐world applications. Vapor processing of materials plays a central role in manufacturing, especially in electronics. Metal–organic frameworks (MOFs) are a class of nanoporous crystalline materials on the brink of breakthrough in many application areas. Vapor deposition of MOF thin films will facilitate their implementation in micro‐ and nanofabrication research and industries. In addition, vapor–solid modification can be used for postsynthetic tailoring of MOF properties. In this context, we review the recent progress in vapor processing of MOFs, summarize the underpinning chemistry and principles, and highlight promising directions for future research.     

The Extra‐Framework Sub‐Lattice of the Metal–Organic Framework MIL‐110: A Solid‐State NMR Investigation

A changeable character : Differences in the dynamics of occluded moieties within the large pores (see graphic) of aluminium 1,3,5‐benzene tricarboxylate framework solid MIL‐110 are a function of the synthesis pH. Host–guest proton‐transfer processes lead to a reversible change in the character of the framework from cationic to neutral, depending on the nature of the extra‐framework moieties.

     

Study on the anti‐sulfur‐poisoning characteristics of platinum–acetylide–phosphine complexes as catalysts for hydrosilylation reactions

A series of platinum–acetylide–phosphine complexes were synthesized and their anti‐sulfur‐poisoning characteristics investigated. In comparison with Speier's and Karstedt's catalysts, the platinum–acetylide–phosphine complexes exhibited both higher catalytic activity and selectivity for the β‐adduct for the hydrosilylation reactions under the same conditions. Furthermore, the complexes also exhibited a strong ability to resist to sulfur‐poisoning. This indicated that the alkyne ligands containing the silyl group had a strong impact on the hydrosilylation reaction. Copyright © 2014 John Wiley & Sons, Ltd.     

Supramolecular Complexation of N‐Alkyl‐ and N,N′‐Dialkylpiperazines with Cucurbit[6]uril in Aqueous Solution and in the Solid State

Water seeds : Complex stoichiometry/composition and degree of oligomerization (oligomeric supramolecular complex formation) of cucurbit[6]uril (CB[6]) with N‐alkyl‐ and N,N′‐dialkylpiperazine were investigated in aqueous solutions by means of isothermal titration calorimetry (ITC), ESI‐MS, NMR and light scattering measurements.

     

Carbon–silica dual‐phase filler,a new‐generation reinforcing agent for rubber. Part VI. Time–temperature superposition of dynamic properties of carbon–silica‐dual‐phase‐filler‐filled vulcanizates

Dynamic properties such as shear modulus, loss modulus, and loss factor were obtained at a low strain amplitude over a wide range of frequencies and temperatures on vulcanizates filled with carbon black, silica, and carbon–silica dual‐phase filler. The data were shifted along the frequency scale. Instead of a single smooth master curve, a pseudomaster curve with a feather‐like structure is obtained. This effect is especially pronounced for the loss factor. Multiple factors may be responsible for this. Among others, filler networking and polymer–filler interaction may play a dominant role. The effect of the carbon–silica dual‐phase filler on the overall dynamic properties of the vulcanizates is similar to that of silica. Their tan δ values are much lower at lower frequencies and are relatively higher at higher frequencies. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1240–1249, 2000