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Thermoresponsive random copolymers consisting of poly(N-isopropylacrylamide) (PNIPAM) and polymerized ionic liquid (IL) poly(1,1,3,3-tetramethylguanidine acrylate) (PTMGA) were synthesized via reversible addition–fragmentation chain transfer radical polymerization (RAFT). The reactivity ratios of NIPAM (rNIPAM = 2.11) and TMGA (rTMGA = 0.56) were determined by the extended Kelen–Todus method. Glass transition temperatures (Tg) of the copolymers were analyzed, which followed the Fox equation very well. The phase transition behaviors of the copolymers in aqueous solution were studied through UV–vis transmission measurements. Their lower critical solution temperature (LCST) ranged from 30.5 to 73.2 °C, depending on the hydrophilic IL content. The apparent pKa related to LCST was determined, and thus the protonation degree was calculated. The hydrophilicity of the copolymers could be regulated by gas treatments. Bubbling CO2 led to lowering the transition temperature while bubbling N2 resulted in its recovery...

A new cycloartane triterpenoid glycoside, named soulieoside R, was isolated from the rhizomes of Souliea vaginata. Its structure was characterized by comprehensive analyses of 1H, 13C NMR, COSY, HSQC, HMBC, NOESY spectroscopic, and HRESIMS mass spectrometric data, as well as chemical methods. The new compound showed weak inhibitory activity against three human cancer cell lines.

A developed three-fluid computational fluid dynamics model was used to investigate the three-phase system in a polyethylene industrial fluidized bed in condensed mode. This model was incorporated with a liquid vaporization modeling scheme comprising heat transfer model, droplet vaporization model, and population balance model to describe liquid evaporation. Numerical results demonstrate that liquid vaporization affects gas velocity distribution, thereby influencing the flow structure. With increasing condensed-liquid contents, the bed temperature gradient at the bed bottom increases and the overall bed temperature decreases. The vaporization rate increases with increasing droplet Sauter mean diameter. Hence, the influence of liquid vaporization is sensitive to droplet diameter.

Successful fabrication of mussel-inspired V-shaped copolymer based materials for pH controllable oil/water separation was reported. Triblock copolymer, polydimethylsiloxane-block-poly(2-hydroxyethyl methacrylate)-block-poly(2-(dimethylamino)ethyl methacrylate) (PDMS- b -PHEMA- b -PDMAEMA) was designed and synthesized through copper(0)-mediated reversible-deactivation radical polymerization (RDRP). Hydroxyl-containing PHEMA block enabled the covalent reaction to occur between polymer and polydopamine (PDA) functionalized substrates. The mixed polymer brushes of oleophilic/hydrophobic PDMS and pH-responsive PDMAEMA endowed the substrates with good pH responsive oil/water wettability and stability. As a proof of concept, the functionalized mesh can separate a range of different immiscible oil/water mixtures with high separation efficiency over 98.5% and high oil flux of 8800–9500 L h −1 m −2 and water flux of 7400–7800 L h −1 m −2 . Additionally, the functionalized sponge realized reversible oil capture and release in aqueous media. Because dopamine through self-polymerization can form strong adhesive films on inorganic and organic substrates in alkalescence solution, the method used in current contribution would be also suitable for producing polymer brush functionalized intelligent materials based on other common substrates.

Kinetic insight into photoinduced Fe-based atom transfer radical polymerization (ATRP) involving monomer-mediated photoreduction was performed by modeling approach for the first time. Preliminary numerical analysis of number-average molar mass (Mn) derivation in this specific system was given. Simulation results provided a full picture of reactant concentration and reaction rate throughout the entire polymerization. Methyl 2,3-dibromoisobutyrate (MibBr2) generated from methyl methacrylate (MMA)-mediated photoreduction as the leading factor for the deviation of Mn from theoretical value was confirmed by reaction contributions in α-bromophenylacetate (EBPA) containing system. Reasonable predictions were made with respect to the polymerizations under a variety of initial conditions. Results show that increasing light intensity will shorten transition period and increase steady state polymerization rate; decreasing catalyst loading will cause the decrease in polymerization rate and Mn deviation; varying initiation activity will slightly increase the time to attain steady state of dispersity (Mw/Mn) evolution and enormously change the fraction of reaction contributions; increasing targeted chain length will extend transition period, decrease steady state polymerization rate, increase Mn deviation degree with same reaction contributions, and decrease the time to attain the steady state of Mw/Mn. The numerical analysis presented in this work clearly demonstrates the unique ability of our modeling approach in describing the kinetics of photoinduced Fe-based ATRP of MMA. © 2017 American Institute of Chemical Engineers AIChE J, 2017

A low-ppm-level iron (Fe)-based photoinduced atom-transfer-radical polymerization (ATRP) under visible-light irradiation was developed. Various ligands, tris(4-methoxyphenyl)phosphine (TMPP), 4,4′-dinonyl-2,2′-dipyridyl (dNbpy), and tris[2-(dimethylamino)ethyl]amine (Me6TREN), were used to enhance the catalytic activity of Fe complexes. Activator FeII complexes were formed by the reduction of FeIII complexes with a monomer under visible-light irradiation. Linear semilogarithmic plots and low polydispersities (Mw/Mn dNbpy > Me6TREN. Additionally, this polymerization could be ceased and restarted, responding to light off and light on. Retention of the chain-end functionality was anal...

Partially water-soluble monomers achieve phase equilibrium between aqueous and dispersed phases, and the interphase mass transfer plays a significant role in suspension polymerization. This work developed a computational fluid dynamics model to simulate the liquid–liquid suspension polymerization process. Complex multiphase flow behaviors and multiscale polymer properties were simultaneously simulated using the combination of an Eulerian–Eulerian two-phase flow model, an atom transfer radical polymerization kinetics model, a population balance model (PBM), and an interphase transfer model. The simulation results for monomer conversion, molecular weight (Mn), polydispersity index (PDI), and Sauter mean diameter (d32) agreed well with the experimental data, thereby validating the soundness of the multiscale model. The proposed model was then employed to predict key variables of the polymerization system. The coupled model can benefit the optimization and scale-up of suspension polymerization reactors with s...

A reactor model has been first developed with the objective to fundamentally comprehend the qualitative influence of the solid polydispersity on the features of a methanol-to-olefins (MTO) fluidized bed reactor. Since coke deposition on the MTO catalyst significantly affects the reaction rate, with its formation usually taking dozens of minutes to achieve the desired coke content, the optimum average coke content was first obtained based on a filtered computational fluid dynamic (CFD) model. Furthermore, comparison of predictions through a CFD method and a reaction engineering approach was conducted. Predictions basically match the experimental data. Subsequently, the influence of the solid particle size distribution on reactor characteristics was comprehensively explored through a filtered CFD method coupled with the population balance model. Results suggested that the particle breakage performed a significant function in MTO fluidized bed reactors, causing particle size to evidently decrease.

Photoinduced atom transfer radical polymerization with an Fe catalyst was successfully performed in aqueous media for the first time. Three water-soluble ligands [i.e., tetrabutylammonium bromide (TBABr), tris[2-(2-methoxyethoxy)ethyl]amine (TDA), and triphenylphosphine-3,3′,3′′-trisulfonic acid trisodium (TPPSA)] were screened for polymerization in aqueous media. Linear semilogarithmic plots, increasing molecular weights (Mn) with conversion, and low dispersity (Đ < 1.40) were achieved by using a new water-soluble phosphine ligand TPPSA, indicating a well-controlled polymerization. Subsequently, the polymerization kinetics of different catalyst concentrations and the targeted degree of polymerizations were investigated. The applicability of this system to the polymerization of different water-soluble monomers was examined. Furthermore, the polymerization can be regulated by switching the light on and off, which further confirmed its controlled and “living” nature. A successful experiment of chain extension suggested the retention of chain-end functionality. A study of the mechanism showed that the activator (FeIIX2/L) and the additional initiator were generated by the photochemical reduction of FeIIIX3/L in the presence of a monomer. This work provides an environmentally benign ATRP to synthesize well-defined water-soluble materials.

Solid particle dispersion and chemical reactions in high-viscosity non-Newtonian fluid are commonly encountered in polymerization systems. In this study, an interphase mass transfer model and a finite-rate/eddy-dissipation formulation were integrated into a computational fluid dynamics model to simulate the dispersion behavior of particles and the mass transfer–reaction kinetics in a condensation polymerization-stirred tank reactor. Turbulence fields were obtained using the standard k–ε model and employed to calculate the mixing rate. Cross model was used to characterize the rheological property of the non-Newton fluid. The proposed model was first validated by experimental data in terms of input power. Then, several key operating variables (i.e. agitation speed, viscosity, and particle size) were investigated to evaluate the dispersive mixing performance of the stirred vessel. Simulation showed that a high agitation speed and a low fluid viscosity favored particle dispersions. This study provided useful guidelines for industrial-scale high-viscosity polymerization reactors.

Knowledge of the heat transfer coefficients in bubble columns can offer valuable references for the design and scale-up of reactors. This work aims to develop reliable correlations that can be applied in precisely predicting the global and local heat transfer coefficients in air-water or air-water-glass beads bubble columns. The influence of superficial gas velocities, column dimensions, volume fraction of particles, internals and radial positions on the heat transfer coefficients is considered in the developed correlations. In addition, the effect of the function forms on the accuracy of calculated local heat transfer coefficients is investigated. The Levenberg-Marquardt Algorithm is used to determine the values of the parameters in the empirical correlations. The recommended correlations can be applied in accurately predicting the heat transfer coefficients in bubble columns.

In this contribution, two well-defined amphiphilic block copolymers, i.e., polystyrene-b-poly(ethylene oxide)-b-polystyrene (PS-b-PEO-b-PS) and poly(ethylene oxide)-b-polystyrene (PEO-b-PS) were synthesized through activators regenerated by electron transfer atom transfer radical polymerization. The as-prepared block copolymers with similar molar mass successfully served as stabilizer for preparing both styrene (St) and methyl methacrylate (MMA) containing HIPEs. The properties of HIPE and the effects of processing conditions (e.g., type and concentration of stabilizer, shearing rate, and aqueous phase volume) on the morphology of the resulting polyHIPEs were investigated by the rheology and scanning electron microscopy analysis. The results show that the block copolymer stabilized HIPEs and the corresponding polyHIPEs possess higher strength compared with the samples stabilized by span80. In addition, PS-based polyHIPEs from the block copolymer stabilized emulsion have an almost closed-cell structure, while PMMA-based polyHIPEs have an open-cell structure. Moreover, it is proven that the concentration of stabilizer plays a critical role in preparing PMMA-based polyHIPEs with high-porosity. It is believed that other functional polymeric porous monoliths can be readily prepared through HIPE templating by using the commonly known PEO-PS block copolymers without the sophisticated surfactant design.

This study investigated the performance of microreactor system in conducting the oxidation of KA oil with nitric acid through mathematical models. Experiments were also carried out via a self-designed microreactor system. Two one-dimensional (1D) pseudohomogeneous models and a two-dimensional (2D) reactor model were developed according to the mass balance and power law kinetics. The calculated results based on different models were compared with experimental data to evaluate the model reliability. The results showed that 1D axial dispersion model and 2D reactor model exhibited comparable accuracy in predicting the conversion of the intermediates, while 2D reactor model was more accurate in predicting the yield of products. With the 2D reactor model, the sensitivity study showed that temperature was the most sensitive parameter. Further studies on the effect of different factors were carried out via the developed model to shed lights on the design and operation of industrial-scale microreactors.

Filtered mesoscale model can be formulated from highly-resolved continuum or discrete simulations. The embedded microscopic homogeneous drag closure (HDC) is of key importance in determining the reliability and accuracy of such simulations. This work investigates the effects of sub-input HDCs on filtered mesoscale predictions using highly-resolved simulations. Quantitative comparisons directly reveal that there are significant differences between the commonly-practiced Wen-Yu drag closure and the direct numerical simulation (DNS) based HDCs, especially for moderate and dense gas-particle flows. Moreover, the HDCs from DNS of static particles agree well with the benchmark data from DNS of dynamic gas-particle flows at very low Reynolds numbers for es > 0.05 ~ 0.10 while Wen-Yu drag is more applicable for the remaining range. Regarding that DNS is commonly implemented over a specific range of operating conditions, an enhanced HDC via refitting more elaborate high-fidelity DNS data (es = [0.01, 0.65], Res = [1, 1000]) from literature is proposed and analyzed.

A reactor model for a methanol-to-olefin (MTO) reaction system was constructed by incorporating a filtered drag model, a filtered gas–solid heat-transfer model, and an MTO kinetic model to probe large-scale reactor behavior and explore optimization. First, the efficiency of several typical gas–solid heat-transfer models and kinetic models was evaluated by comparing predicted results with experimental data. Second, the effect of two significant operation parameters, namely, reaction temperature and water-to-methanol ratio, were studied based on the above-mentioned model. Predictions suggested an optimum catalyst residence time (∼33 min) and an average coke content (∼6.74%) of this MTO system. In addition, relatively high temperature maximized ethylene production, and the water introduced into the feed significantly attenuated coke deposition. This work is the first to conduct coarse-grid simulations by using the developed effective filtered-CFD coupled model to probe the reaction flow and explore optimizat...

Gas–liquid–solid fluidized bed reactors (FBRs) are of considerable importance as proved by their widespread use and popularity in various industrial processes, which results in extensive theoretical analyses, experimental investigations and computational fluid dynamics (CFD) studies in the past. Many reviews have been published concerning the theoretical and experimental works of three-phase FBRs while little effort is on the CFD approach of three-phase fluidization system. This review attempts to summarize and analyze CFD simulations for these three-phase fluidization systems from two aspects: the fundamentals and their applications, which are of paramount importance to the formulation of strategies for scale-up, design and control of three-phase FBRs. The fundamentals of CFD approach in the three-phase FBRs are focusing on various multi-scale models, such as pseudo two fluid model, three fluid model, two fluid model + discrete particle method (DPM), CFD + the front tracking (FT)/front capturing (FC) + DPM etc. and the coupling fundamental theories of interaction forces. With the emphasis on the hydrodynamics of individual phase at macroscopic or microscopic level, the applications of CFD approach for three-phase fluidization system are analyzed. This review also proposes that future emphasis and challenges of CFD simulation for three-phase FBRs are to present specific and appropriate closure laws for interphase momentum exchange, incorporate chemical reactions transport phenomena properties into numerical models, and develop measurement techniques and provide more experimental data for three-phase systems.

In this work, a series of block copolymers of poly(2,2,3,4,4,4-hexafluorobutyl methacrylate)-block-poly[2-(dimethylamino)ethyl methacrylate] (PHFBMA-b-PDMAEMA) were synthesized via photo-induced atom transfer radical polymerization (photoATRP) at room temperature. By the introduction of PDMAEMA segment, the hydrophilicity of the silicon wafer surface spin-coated with PHFBMA homopolymer was improved. Furthermore, the study of tunable surface wettability showed that the surface wettability was pH-dependent and thermal-independent at pH 2 and 10. The as-fabricated surface coated with PHFBMA110-b-PDMAEMA187 showed switchable water contact angle from 85.4° at pH > 4 to 55.0° at pH 2 due to the protonation and deprotonation of tertiary amine groups of PDMAEMA. However, because of the ascendancy of protonated PDMAEMA at pH 2 and the decreased LCST at pH 10, the wettability of the as-prepared surfaces was thermal-insensitive. Finally, surface morphology and composition investigation showed that the property of wettability-controllable surface was not only influenced by surface composition, but also affected by chain conformation. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016

In this work, a photoinduced iron(III)-based atom transfer radical polymerization (ATRP) without any reducing agents and additional initiators was suggested. In addition, detailed kinetic studies, including the effects of ligand and catalyst concentrations on polymerization kinetics, and the polymerization behaviors using various solvents and monomer types were evaluated for this new polymerization technique. Results showed that photoinduced iron(III)-mediated ATRP using 5000 ppm catalyst loading with 1 equiv of ligand in N,N-dimethylformamide (DMF) produced poly(methyl methacrylate) with low molecular weight distribution (Mw/Mn < 1.45) and that the evolution of molecular weight (Mn) was linearly related to monomer conversion. 1H NMR analysis confirmed that the resulting polymer prepared through photoinduced ATRP in the present work was initiated by methyl 2,3-dichloroisobutyrate. Facile temporal control and the successful chain extension highlighted the good chain-end functionality of the resulting polym...

In this work, numerical simulations of cylindrical bubble column are performed using the Euler–Euler approach incorporated with a population balance model (PBM). First, three drag models and their corresponding modified models with the wake acceleration are incorporated into the coupled approach in order to evaluate the effectiveness of these drag models. The simulated time-averaged local gas holdups and normalized axial liquid velocities using different drag equations are compared with the experimental data, showing that only the PBM-customized drag model with the wake acceleration (cf., the application of a correction factor) can reproduce the measured flow field data. Subsequently, the applicability of the coupled approach with the effective drag model is further evaluated at various superficial gas velocities and gas distributors. The simulated results accord well with the experimental data at high gas velocities. However, the model greatly underestimates the radial local gas holdup and the total gas holdup at low gas flow rates. Additionally, the simulated results demonstrate that the opening area and orifice geometry play a significant role in total aeration and the triple-ring gas distributor produces more uniform radial profiles of local gas holdup and normalized liquid velocity than the multi-orifice one, thus leading to poor mixing efficiency in the bubble column.

A computational fluid dynamics (CFD) model based on the Eulerian–Eulerian approach, coupled with polymerization kinetics, has been implemented to describe the gas–solid flow behaviors in a gas phase polyethylene fluidized bed reactor (FBR). The model is firstly validated by the classic equations and reference data, and then extended to simulate the gas-phase polyethylene FBR under super-condensed mode for the first time. The influence of three important operating conditions ( i.e ., inlet gas velocity, inlet gas temperature, and condensable component isopentane concentration) on gas–solid flow hydrodynamics is investigated to give qualitative and quantitative insights on how these factors affecting FBR performances (like bed expansion, bed temperature and productivity) under super-condensed mode through CFD approach. The simulation results demonstrate that with the increase of inlet gas velocity, the bed expansion increases rapidly and the number of particles at the lower portion of the bed reduces while raises at the higher position. The rise of the bed temperature is mainly contributed by the increased exothermic reaction rate as the inlet gas temperature increasing, which is also influenced by the concentration of condensable component isopentane. The simulation results show that bed temperature decreases with the increase of condensable isopentane concentration in gas stream. It is found that the method of heat removal through the latent heat of vaporization is extremely significant and can effectively increases reactor productivity without enlarging the size of the reactor under super-condensed mode.

An iron- and methyl methacrylate (MMA)-based electrochemically mediated atom transfer radical polymerization (eATRP) system was developed for the first time. Kinetic behaviors, including the effect of applied potential and catalyst loading, were systematically investigated. Results indicated that with more negative electrode potential, the polymerization rate increased until the mass transport limitation was reached. However, reduction of the catalyst loading had adverse effects on polymerization behaviors, such as decreased polymerization rate and increased molecular weight distributions (Mw/Mn). In addition, a kinetic model based on the method of moments was also constructed to explain the mismatch in Mn and Mn,theo. Simulation results showed that slow initiation significantly influenced on the kinetic behaviors in this system. Iron(II) bromide-catalyzed normal ATRP, iron(III) bromide-catalyzed eATRP, and copper(II) bromide-catalyzed eATRP were conducted to compare and elucidate their respective polymer...

Reversible-deactivation radical polymerization (RDRP) techniques have received lots of interest for the past 20 years, not only owing to their simple, mild reaction conditions and broad applicability, but also their accessibility to produce polymeric materials with well-defined structures. Modeling is widely applied to optimize the polymerization conditions and processes. In addition, there are numerous literatures on the kinetic and reactor models for RDRP processes, which show the accessibility on polymerization kinetics insight, process optimization, and controlling over chain microstructure with predetermined molecular weight and low dispersity, copolymer composition distribution, and sequence distribution. This review highlights the facility of the method of moments in the modeling field and presents a summary of the present state-of-the-art and future perspectives focusing on the model-based RDRP processes based on the method of moments. Summary on the current status and challenges is discussed briefly.

In this work, a three-dimensional (3-D) filtered two-fluid model (TFM) was developed to describe the gas–solid flow behavior in a large-scale methanol-to-olefins (MTO) fluidized bed reactor (FBR). The cold-model flow behaviors were characterized successfully via the filtered TFM with a coarse grid. A coarse-grid sensitivity test was first carried out, and the filtered model was testified using predictions from classical models and the experimental data. Moreover, four drag models have been incorporated into the TFM for evaluating the effectiveness of these models at the same coarse-grid condition. Subsequently, the effects of some important model parameters including solid stresses, wall corrections and filter size on the flow behaviors were also investigated numerically. Finally, the filtered model was applied to predict the effects of the operating gas velocity, distributor shape and solid particle size. The results suggested the effectiveness of the sub-grid models for simulating large-scale MTO FBRs at coarse-grid conditions. This study further confirmed that the filtered drag coefficient correlation plays a significant role in capturing flow behaviors and the filter size is nearly independent on the grid size when the filter size is larger than or equal to twice the grid size. The simulation results by coarse-grid also show that the catalyst particles are easier to be fluidized with the increase of the operating gas velocity. It is also found that a triangle-shaped distributor strengthens the mixing behaviors and weakens the clustering of the near-wall regions. Additionally, our study indicates that the clustering phenomena near the wall regions are more obvious with the decrease of the catalyst particle size.

A CFD simulation was proposed to investigate the electrostatic effect on the hydrodynamic behavior of turbulent gas–solid flow in FCC risers. The simulation was first verified using the open experimental data with expected electrostatic effects observed in FCC risers. The influences of several operating parameters on the degree of electrification in FCC risers were analyzed, such as surface charge densities, pressure, gas velocity. It was noted that the gas velocity played a highly significant role compared with solid flux, while the effect of pressure was relatively weak. Further analysis showed that a much stronger electrostatic effect was found in small-scale FCC risers than their large-scale counterparts, and in addition, the major regions affected by the electrostatic charge depend on the scale of the riser. Finally, an external electric field was applied to optimize the flow field distribution in the FCC riser. The results of the electrostatic effects on the hydrodynamic behaviors in FCC risers are of great use in providing a reference for the optimization of FCC risers and their scaling.

The molecular properties of polymers are greatly influenced by operation parameters during polymerization in reactors. Since operation parameter distributions in reactors also result in molecular property distributions, polymerization bridges the gap between molecular properties and operation parameters. The combination of the computational fluid dynamics technology with the method of moments to form a uniquely coupled model was used to describe multiscale mixing fields in the reactor. The coupled model was validated by open experimental data, and the effects of polymerization kinetics on macroscopic and microscopic fields were investigated numerically. Also, the coupled model was applied to numerically predict the impacts of some key operation conditions on the main macroscopic flow field parameters and polymer molecular properties.

Smart polymeric surfaces with switchable oil/water wettability are ideal candidates for oil/water separation, which still suffer from significant restrictions in practical separation applications. Appropriate fabrication method should be explored to devise and mass produce smart polymeric membranes. Herein, we prepared two smart membranes through solution-casting method and electrospinning technology, respectively, based on temperature-responsive copolymer poly(methyl methacrylate)-block-poly(N-isopropylacrylamide) (PMMA-b-PNIPAAm). According to the thermo-responsive component PNIPAAm, both membranes exhibited temperature-modulable oil/water wettability. Electrospun fibrous membrane owned an extended transition range of oil/water wettability compared to polymer solution-casting membrane because of its 3D network porous structure of the random entangled fibers. The as-prepared membranes realized gravity-driven oil/water separation with efficiency higher than 98% through regulating temperature. Solution-casting membrane exhibited a water flux of about 6200 L h−1 m−2 and an oil flux of about 1550 L h−1 m−2. By contrast, characteristics of the high porosity and the large surface-to-volume ratio made the electrospun fibrous membrane achieve higher fluxes of about 9400 L h−1 m−2 for water and about 4200 L h−1 for oil. Electrospinning is a powerful and cost-effective method to construct smart membrane with excellent wetting property and separation performance.

Interest in functional soft matter with stimuli-responsive wettability has increasingly intensified in recent years. From the chemical product engineering viewpoint, this study aims to fabricate reversible pH-responsive polymeric surfaces with controllable wettability using [poly(2,2,3,4,4,4-hexafluorobutyl methacrylate)-block- poly(acrylic acid) (PHFBMA-b-PAA)] block copolymers. To attain this aim, three block copolymers with different PAA segment lengths were synthesized for the first time through Cu(0)-mediated reversible-deactivation radical polymerization and hydrolysis reaction. pH-induced controllable wettability was achieved by spin-coating the resulting block copolymers onto silicon wafers. Results showed that the pH-responsive wetting behavior was introduced by incorporating the PAA block, and that the responsiveness of as-fabricated surfaces was greatly influenced by PAA content. All three evolutions of water contact angle with pH shared a similar inflection point at pH 5.25. Furthermore, on the basis of the wetting properties and mechanism understanding, the application of copolymer coated meshes in layered water/oil separation was exploited. Given their superhydrophilicity and underwater superoleophobicity, PHFBMA70-b-PAA148 and PHFBMA70-b-PAA211 coated stainless steel meshes (SSMs) can efficiently separate water from different mixtures of organic solvent and water with high flux. However, considering long-term use, the PHFBMA70-b-PAA148 coated SSM with good stability may be the best copolymer for water/oil separation. Therefore, a coordination of structure, composition, and functionality was necessary to enable practical applications of the functional materials. © 2016 American Institute of Chemical Engineers AIChE J, 62: 1758–1771, 2016

The class method (CM) has been frequently applied in solving population balance equations (PBEs) for the CFD-PBM simulation of bubble columns. There are four parameters in the CM: the volume ratio between successive bubble classes (rv), the minimum diameter (dmin), the maximum diameter (dmax) and the critical diameter (dc) that is used to distinguish small bubbles and large bubbles. These parameters have a significant impact on the computational precision and efficiency. In this work, numerical simulations are performed to investigate the effects of these parameters on the simulation of two typical bubble columns operated at heterogeneous regime. The simulation results quantitatively present the influences of these parameters on the simulated local gas holdup and global bubble size distribution. The simulated radial profiles of gas holdup at different heights are compared with experimental data. The optimized scheme for the values of these parameters in the CM is proposed.

This work investigates the effects of coalescence and breakup models on the radial distribution of gas holdup and local bubble size distribution in a laboratory scale bubble column operated at 0.11 m/s, 0.14 m/s, 0.19 m/s and 0.23 m/s. The results quantitatively show the influences of bubble coalescence due to various mechanisms, coalescence efficiency calculated by different models, modification coefficients for coalescence rates, critical energy required for breakup and bubble breakage caused by large scale eddies and viscous shear on numerical simulations. Furthermore, qualitative analysis is performed to analyze the effects of these factors. The performance of various models is evaluated (e.g. Han’s breakup model and Das’s coalescence model). Some optimized combinations of coalescence and breakup models that can be used to accurately predict the local gas holdup and bubble size distribution in laboratory scale bubble columns operated at heterogeneous regime are proposed.

Preparation of two-component materials having morphologies with bicontinuous minor and major components is challenging. An innovative method has been developed to synthesize bicontinuous polymeric monoliths based on high internal phase emulsion (HIPE) templating. This work demonstrated a protocol of dual-hydrophobic bicontinuous material of glassy polystyrene (PS) and elastic poly(butyl acrylate) (PBA). The PS scaffold was prepared through polymerizing styrene (St) as the external phase of HIPE with an aqueous free radical initiator, in the presence of divinylbenzene (DVB) as a crosslinker. The resulting PS scaffolds were then employed as templates to absorb butyl acrylate (BA) mixed with ethylene glycol dimethylacrylate (EGDMA). Results suggested that the polymeric monoliths possessed a bicontinuous structure and good compatibility in the bulk state. This work provides a new approach for the synthesis of bicontinuous two-component materials.

Our prior work developed an effective material-property-dependent sub-grid model (SGM) for efficient coarse-grid riser flow simulations. To apply this SGM for the purpose of designing and scaling-up riser reactors reliably, quantitative assessment in its predictive capability is required. Here, we quantify the influence of various model parameters with respect to time-averaging, grid resolution, time step, discretization scheme for convection terms, and solid-wall slip condition by implementing extensive three-dimensional coarse-grid simulations. Moreover, we compare several crucial SGM-based coarse-grid and coarse-grained methods to reveal their advantages and disadvantages. Detailed parametric sensitivity analyses demonstrate that the accurate determination of SGM appears to play a dominant role in successfully predicting hydrodynamics. The optimal selection of the other model parameters is suggested to realize a compromise between computation speed and accuracy. Overall, this fundamental study helps to quantitatively understand the predictability of SGMs for coarse-grid simulations of large-scale riser reactors.

In this work, a computational fluid dynamics (CFD) approach based on two-fluid model (TFM) is introduced to describe the reversible two-step reactions found in the chemisorption process of ${\text{C}}{{\text{O}}_2}$ by an aqueous ${\text{NaOH}}$ solution in a lab-scale bubble column reactor. The population balance model (PBM) is applied to track the bubble size distribution with considering the coalescence and breakage terms, which then leads to a CFD-PBM model for describing the chemisorption of CO2 in an aqueous ${\text{NaOH}}$ solution. Drag force is considered for the interfacial momentum transfer and a modified PBM-customized drag model with the correction factor is subsequently adopted, in which the contribution of different bubble size groups in each computational cell is computed. The tested boundary conditions include superficial gas velocities, gas-inlet sparger and the reactor dimension. Detailed and comprehensive investigations are done in the evolution of gas holdup, pH value, concentration distribution and bubble diameter distribution which are essential in optimizing the reactor performance in terms of yield and selectivity. Importantly, the current CFD-PBM model is able to predict the entire reaction process.

Ferrite catalysts with high intraparticle pore volume and surface area are frequently used in the oxidative dehydrogenation of butylene. Whether the non-inclusion of intraparticle transfer limitation in fixed-bed reactors for oxidative dehydrogenation over ferrite catalysts in previous studies is appropriate remains unclear. In this study, we attempt to verify this process using a multi-scale modeling technology. The multi-scale model consists of a porous medium model and a single particle model under the oxidative dehydrogenation condition. This model can predict the influences of intraparticle transfer on the main component distributions in reactors and demonstrate that the intraparticle transfer limitation is obvious.

Wastewater contaminated with oil or organic compounds poses threats to the environment and humans. Efficient separation of oil and water are highly desired yet still challenging. This paper reports the fabrication of a smart fiber membrane by depositing pH-responsive copolymer fibers on a stainless steel mesh through electrospinning. The cost-effective precursor material poly(methyl methacrylate)-block-poly(4-vinylpyridine) (PMMA-b-P4VP) was synthesized using copper(0)-mediated reversible-deactivation radical polymerization. The pH-responsive P4VP and the underwater oleophilic/hydrophilic PMMA confer the as-prepared membrane with switchable surface wettability toward water and oil. The three-dimensional network structure of the fibers considerably strengthens the oil/water wetting property of the membrane, which is highly desirable in the separation of oil and water mixtures. The as-prepared fiber membrane accomplishes gravity-driven pH-controllable oil/water separations. Oil selectively passes through the membrane, whereas water remains at the initial state; after the membrane is wetted with acidic water (pH 3), a reverse separation is realized. Both separations are highly efficient, and the membrane also exhibits switchable wettability after numerous cycles of the separation process. This cost-effective and easily mass-produced smart fiber membrane with excellent oil-fouling repellency has significant potential in practical applications, such as water purification and oil recovery.

A detailed kinetic model was constructed using the method of moments to elucidate the electrochemically mediated atom transfer radical polymerization (eATRP). Combined with electrochemical theory, the reducing rate coefficient relevant to the overpotential in eATRP was coupled into the kinetic model. The rate coefficients for eATRP equilibrium and the reducing rate coefficient were fitted to match the experimental data. The effects of catalyst loading, overpotential, and application of programmable electrolysis on the eATRP behavior were investigated based on the tested kinetic model. Results showed that the apparent polymerization rate exhibited a square root dependence on catalyst loading. In addition, a more negative potential accelerated the polymerization rate before the mass transport limitation was reached. This phenomenon indicated that the polymerization rate could be artificially controlled by the designed program (i.e., stepwise and intermittent electrolysis programs). What is more, the normal ATRP, photo-ATRP, and eATRP were compared to obtain a deeper understanding of these ATRP systems. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4347–4357, 2015

A three-dimensional (3D) reactor model based on the Eulerian-Eulerian approach was applied to describe the gas-solid flow and heat transfer performance in a radial flow moving bed reactor (RFMBR). A six-lumped kinetic model for the catalytic pyrolysis of C4 hydrocarbon was employed. The heat transfer characteristics and species concentration profiles were investigated in the reactor under various reaction conditions. Effects of operation parameters and reactor structures on the reactor performance were also evaluated and optimized numerically. Simulation results show that there exists a good heat transfer performance between gas and solid phases in the catalyst bed. The temperature profiles and the species yield distributions are different with respect to bed height positions. Moreover, the results indicate that product yield is more sensitive to the reaction temperature than to the dilution rate and the reaction residence time. For the Z-type centripetal flow RFMBR, an annular tube with an inverted cone structure is helpful to improve the uniformity of flow distribution and increase low-carbon olefins yields.

With the idea of “an old method for a new mechanism,” a detailed kinetic insight into photochemically mediated atom-transfer radical polymerization (photo ATRP) was presented through a validated comprehensive model. The simulation mimics the experimental results of the model system using optimized photochemically mediated radical generation rate coefficients. The activator and radical (re)generated from the photo mediated reactions endow the photo ATRP with unique features, such as rapid ATRP equilibrium and quick consumption of initiator with a small amount of residual. The effect of the reaction parameters on ATRP behaviors was also investigated. Results showed that the acceleration of polymerization rate follows the square root law in the following three cases: the overall photochemically mediated radical generation rate coefficients (kr), the free ligand concentration, and the initiator concentration. However, the independence of the apparent propagation rate coefficient ( kpapp) on the square root of catalyst concentration might be attributed to the result of the synergy between the activators regenerated by electron-transfer ATRP and the initiators for continuous activator regeneration ATRP mechanism. The photo ATRP is able to design and prepare various polymers by carefully tuning the conditions using the model-based optimization approach. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1947–1958, 2015

To search for robust CO2 capture materials, two types of ionic liquids, namely, (p-vinylbenzyl)trimethylammonium tetrafluoroborate ([VBTMA][BF4]) and (p-vinylbenzyl)trimethylammonium hexafluorophosphate ([VBTMA][PF6]), were synthesized and immobilized onto a mesoporous silica (meso-silica) support by the surface-initiated atom-transfer radical polymerization (SI-ATRP) method. The prepared sorbents meso-SiO2–P[VBTMA][BF4] and meso-SiO2–P[VBTMA][PF6] were well-characterized. Their adsorption behaviors toward CO2 from simulated flue gases at different pressures were investigated using an adsorption column. Based on a simulated flue gas containing 10 vol % CO2 at 30 °C, the highest CO2 adsorption capacity of meso-SiO2–P[VBTMA][BF4] was 0.4025 mmol g–1, whereas the corresponding value for meso-SiO2–P[VBTMA][PF6] was 0.3793 mmol g–1. Compared with pure poly(ionic liquid)s, the existence of a meso-silica core improves the CO2 capture capacity. Furthermore, the presence of vapor can improve the CO2 capture capaci...

Real solid systems in polymerization fluidized bed reactors (FBRs) are characterized by wide particle size distributions that change continuously due to particle micro-behavior, growth and aggregation, etc. Simulations of such gas–solid flow hydrodynamics require the solution of a coupled computational fluid dynamics (CFD)-population balance equation (PBE) model, i.e. the CFD-PBM. Therefore, the analysis of the existing numerical methods for solving the PBE is important for the ability of the numerical prediction of the coupled model. Three representatively numerical moment-based methods, namely the quadrature method of moments (QMOM), the direct quadrature method of moments (DQMOM) and the fixed pivot quadrature method of moments (FPQMOM), were used to solve the PBE for evaluating the effect of numerical method. Comparative results demonstrated the suitability of the FPQMOM for modeling polymerization FBRs with simultaneous polymerization particle growth and aggregation.

From the chemical reactor engineering viewpoint, the material flow pattern in continuous reactor can influence the reaction characteristics and reactor performance. Based on the molar balance equations and the method of moments, a tubular reactor model was developed, which was validated using the experimental data from the open reports. Then the atom transfer radical copolymerization (ATRcoP) of methyl methacrylate (MMA) and 2-(trimethylsilyl) ethyl methacrylate (HEMA-TMS) under different axial dispersions in tubular reactor were simulated using the developed model. The main ATRcoP behaviors and polymer micro-characteristics were obtained. Finally, the effects of flow patterns (including the CSTR and PFR modes) on the ATRcoP characteristics were investigated using the models. The simulation results show that the reaction characteristics of the same ATRcoP system produced in flow with different axial dispersion levels are obviously different. Moreover, the comparison of properties such as monomer conversion, dispersity, copolymer composition, and chain-end functionality between two extreme flow patterns, i.e plug flow in tubular reactor and completely mixed flow in CSTR, were performed. The compositions along the copolymer chain for the two flow modes are very close. As for the other three properties, the tubular reactor has its own comparative advantages over the CSTR.

1,2,4-Triazolium perfluorobutanesulfonate (1), a novel, pure protic organic ionic plastic crystal (POIPC) with a wide plastic crystalline phase, has been explored as a proof-of-principle anhydrous proton conductor for all-solid-state high temperature hydrogen/air fuel cells. Its physicochemical properties, including thermal, mechanical, structural, morphological, crystallographic, spectral, and ion-conducting properties, as well as fuel cell performances, have been studied comprehensively in both fundamental and device-oriented aspects. With superior thermal stability, 1 exhibits crystal (phase III), plastic crystalline (phase II and I) and melt phases successively from −173 °C to 200 °C. Differential scanning calorimetry and temperature-dependent powder X-ray diffraction (XRD) measurements together with polarized optical microscopy and thermomechanical analysis reveal the two solid–solid phase transitions of 1 at 76.8 °C and 87.2 °C prior to the melting transition at 180.9 °C, showing a wide plastic phase (87–181 °C). Scanning electron microscopy displays the morphology of different phases, indicating the plasticity in phase I. Single-crystal XRD studies reveal the molecular structure of 1 and its three-dimensional N–H⋯O hydrogen bonding network. The influence of the three-dimensional hydrogen bonding network on the physicochemical properties of 1 has been highlighted. The temperature dependence of hydrogen bonding is investigated by variable-temperature infrared spectroscopy. The sudden weakening of hydrogen bonds at 82 °C seems to be coupled with the onset of orientational or rotational disorder of the ions. The temperature dependence of ionic conductivity in the solid and molten states is measured via impedance spectroscopy and current interruption technique, respectively. The Arrhenius plot of the ionic conductivity assumes a lower plateau region (phase I, 100–155 °C) with a low activation energy of ∼36.7 kJ mol−1 (i.e. ∼0.38 eV), suggesting likely a Grotthuss mechanism for the proton conduction. Variable-temperature infrared analysis, optical morphological observations, and powder XRD patterns further illustrate the structural changes. Electrochemical hydrogen pumping tests confirm the protonic nature of the ionic conduction observed in the lower plateau region. Finally, measurements of the open circuit voltages (OCVs) and the polarization curves of a dry hydrogen/air fuel cell prove the long-range proton conduction. At 150 °C, a high OCV of 1.05 V is achieved, approaching the theoretical maximum (1.11 V).

A multi-scale product model has been built to characterize the polypropylene (PP) formation dynamics in a catalytic FBR. For the first time, the gas–solid flow field, the morphological and molecular properties of particles, as well as their dynamics can be simultaneously obtained by solving the unique model that couples a CFD model, a population balance model (PBM) and moment equations. The quantitative relationships between the operating conditions and the multi-scale particle properties have been further established. The results demonstrate that the product model can be used to guide a multi-scale generalization of the polymer product from chemical process to product engineering.

Thermo-responsive brush copolymers poly(methyl methacrylate (MMA)- co -2-(2-bromoisobutyryloxy)ethyl methacrylate (BIEM)- graft -(N-isopropyl-acrylamide) (NIPAAm)) were synthesized using Cu-mediated “living” radical polymerization (LRP) approach. Varied grafting densities of the brushes were obtained through adjusting backbone structure as random, gradient and block respectively. The effect of grafting densities on their thermo-responsive phase transition behaviors in aqueous solution and on surface were investigated in detail. The lower critical solution temperature (LCST) of brush copolymers in solution was adjusted as 35, 37 and 38 °C through random, gradient and block backbone structure respectively. Their structure tunable thermo-responsive phase transition in solution were further confirmed by the different micelle aggregation behaviors above LCST which monitored by transmission electron microscopy (TEM) images and dynamic light scattering (DLS). In addition, surfaces modified by the resulted brush copolymers have a temperature tunable wettability based on thermo-responsive phase transition in solid, the similar WCA variation range of three brush copolymers implies that the composition of backbone does not much affect the switchable wettability of surfaces.