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The adipic acid is an important intermediate in the production of nylon, polyurethane and polyester resins. The industrial approach for preparing adipic acid is through the liquid catalytic oxidation of KA oil with nitric acid. In this work, a comprehensive model is developed for this reaction based on the kinetic study conducted in a continuous flow tubular reactor. The kinetic model fits well with the experimental results across the experimental conditions, and the average relative error between the calculated and experimental values is 5.7%. Results show that there was an induction period at the early stage of reaction. Moreover, it is found that at temperature range of 328–358 K, the formation rate of adipic acid strongly dependents on the temperature and nitric acid concentration. The developed model is used to predict the yield of adipic acid at 359–368 K. The work in this study could provide much knowledge for industrial tubular reactor design.

One of the challenges for modelling of polymerization kinetics is the detailed description of the molecular build-up of both linear and non-linear chains, specifically those with many grafts and crosslinks. Such grafted/crosslinked (co)polymers are relevant as emulsifiers, surface-modifying agents, coating materials, and compatibilizers. In the present work, we put forward a coupled matrix-based Monte Carlo (CMMC) concept to be successful in this respect, avoiding computational stiffness. The CMMC concept is illustrated for single phase grafting of polybutadiene (PB) with styrene (St) at 343 K by limiting the St conversion to 30%. Considering literature kinetic parameters, a benchmark for average characteristics as obtainable by deterministic method of moments simulations is first presented to then gradually extend the level of modelling output addressing (i) conventional grafting performance indicators (e.g. the grafting yield and mass ratio); (ii) univariate chain length distributions for all macrospecies types (polystyrene, PB, PB with only T grafts, PB with at least one H graft, etc.); (iii) bivariate St–butadiene distributions showing a compositional drift, due to the kinetic tendency to attack longer chains if they are sufficiently present and the competition between grafting and crosslinking; (iv) the explicit molecular build-up of individual molecules predicting the positioning of the St–Bd and St–St connectivity points and the chain formation history. It is demonstrated that the CMMC tool allows the simulation of the contribution and structure of molecules that are hard to access purely experimentally, so that in the long run, novel structure–property relationships are within reach. It is also showcased that consideration of elementary reactions is highly recommended and that even at 343 K, thermal self-initiation with St and related chain transfer reactions matter for a full appreciation of molecular variations. The current work also opens the pathway to identifying pragmatic equations for the experimentalist and online control benefiting from a detailed CMMC solution under any desired conditions.

The kinetics of the ultraviolet light-induced solution atom transfer radical polymerization (ATRP) of methyl acrylate using titanium oxide (TiO2) was investigated through experiments and modeling b...

An electrochemically mediated atom transfer radical polymerization (eATRP) of methyl acrylate (MA) in 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6) ionic liquid (IL) was reported. Remarkably, the kinetic results revealed an extremely fast and well controlled polymerization in the presence of tris(2-(dimethylamino)ethyl)amine (Me6TREN). The monomer conversion reached more than 90% within a period of 300 s. Computational and simulation results indicated that the IL induced acceleration of polymerization can be attributed to the increased value of k t / k p 2 compared to the associated literature value. Additionally, polymerizations under different conditions, including ligand types, monomer/IL ratios, catalyst loadings, and targeted degrees of polymerization were explored. All the kinetic plots suggested superfast polymerization rates with good control over molecular weight and dispersity. Furthermore, the livingness of MA polymerization was confirmed by chain extension experiment. This work provides a new insight into eATRP in IL through experimentation and simulation and thus enriches the knowledge of reaction features of eATRP.

Hydrogenation of CO2 into methanol is promising for achieving the sustainable energy economy, but still has some problems, e.g. low methanol selectivity and high operation pressures (>10 atm). Herein, we prepared a Pt/film hybrid with highly dispersed Pt nanoparticles, and combined Pt/film with In2O3 to form a Pt/film/In2O3 catalyst. By using a dielectric barrier discharge (DBD) plasma reactor, a CO2 conversion of 37.0% and a methanol selectivity of 62.6% are achieved in the hydrogenation of CO2 with H2 on Pt/film/In2O3 at 1 atm and 30 °C. These are higher than those on Pt/In2O3 prepared by the conventional high-temperature H2 reduction (24.9% and 36.5%) and commercial Cu/ZnO/Al2O3 (25.6% and 35.1%). The high-energy electrons of the DBD plasma trigger the CO2 hydrogenation at 1 atm and 30 °C. The higher Pt nanoparticles dispersion, film and In2O3 promote the adsorption of CO2 on Pt/film/In2O3, thus enhancing the hydrogenation of CO2 into methanol. These results are helpful for efficient methanol production from CO2 hydrogenation under atmospheric pressure.

A water-soluble organic photoredox catalyst, 3,7-methoxypolyethylene glycol 1-naphthalene-10-phenoxazine (Naph-PXZ-PEG), that can catalyze aqueous organocatalyzed atom transfer radical polymerization (ATRP) via oxidative quenching cycle has been reported for the first time. Comparative studies of Naph-PXZ-PEG and EosinY involved aqueous organocatalyzed ATRP systems have been done via polymerization experiment and kinetic modeling approach. Results showed that the polymerization via oxidative quenching cycle in Naph-PXZ-PEG system proceeded much faster and higher initiator efficiency than the polymerization via reductive quenching cycle in Eosin Y system under same conditions. Detailed information of the Naph-PXZ-PEG was presented by experiments and density functional theory (DFT) simulation. A series of kinetics experiments under different catalyst loadings, initiator concentrations, “on-off” switch of light and chain extension have been conducted and confirmed the good controllability of the current system and high end-group fidelity. This work provides a systematic study on developing an effective water soluble organic catalyst for the preparation of the well-defined polymers by a “green” and sustainable ATRP.

The Kolbe-Schmitt reaction is the traditional method for preparing 2,4- and 2,6- dihydroxybenzoic acid (2,4- and 2,6-DHBA). In this work, accurate kinetic models for the Kolbe-Schmitt synthesis of 2,4- and 2,6-DHBA were successfully developed. The relative errors between the theoretical and experimental 2,4-DHBA equilibrium yields are less than 3.7% as T = 348–473 K, [C6H6O2] = 0.4–0.8 M and [KHCO3] = 1.2–4.0 M. The effects of reaction temperature, reaction time, KHCO3 and resorcinol (C6H6O2) concentrations on the formation rates and the yields of 2,4- and 2,6-DHBA were investigated by the developed models. Results show that the 2,4-DHBA equilibrium yield exhibits a strong dependence on the KHCO3 concentration, and the formation rate of 2,4-DHBA is strongly dependent on the reaction temperature. Furthermore, the reaction time is a critical factor in controlling the ratio of 2,4-DHBA to 2,6-DHBA as the reaction temperature varies from 433 to 473 K. Additionally, the results of the present work deepen the understanding of the reaction mechanism, e.g. the rate-determining step and main reaction pathway of 2,6-DHBA formation.

Hydrodynamics characteristics of a fast and highly exothermic liquid-liquid oxidation process with in-situ gas production in microreactors was studied using a newly developed experimental method. In the adipic acid synthesis through the K/A oil oxidation with nitric acid, bubble generation modes were divided into four categories. The gas production became more intensive and unstable, even explosive with increasing the oil phase feed rate and the temperature. A novel automatic image processing method was established to monitor the instantaneous fluid velocity online by tracking the gas-liquid interface. The axial fluid velocity at the same location was unstable with obvious fluctuation due to the unstable gas production rate. Furthermore, the actual average residence time was obtained easily with being only 36% of the space-time minimally, beneficial for establishing accurate kinetic and mass transfer models with time participation. Finally, an empirical correlation was developed to predict the actual residence time under different conditions.

A thermo-responsive copolymer with a gas-switchable LCST-type phase transition was synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization of N-isopropylacrylamide (NIPAM) and glycidyl methacrylate (GMA), followed by post-polymerization functionalization with sodium 3-amino-1,2,4-triazole (ATANa). Incorporating ionic moieties provides an elevated cloud point of 61 °C. Importantly, both CO2 and SO2 cause a reduction in the cloud point of the polymer solution. The CO2-triggered system can be easily and fully recovered to its initial state by introducing an inert gas (e.g. N2), whereas the SO2-triggered system shows only partial recovery. The pH-dependent phase transition behaviors confirm that the gas bubbling-induced pH changes contribute to the gas-switchable cloud point of P(NIPAM-co-(GMA-ATANa)). In addition, P(NIPAM-co-(GMA-ATA)) (ATA: 3-amino-1,2,4-triazole), a counterpart of P(NIPAM-co-(GMA-ATANa)), was prepared and the relevant solution phase transition behavior was studied. Its cloud point shift in response to gas bubbling and pH adjustment is opposite to that of P(NIPAM-co-(GMA-ATANa)), indicating that the latter does not result from the protonation of amidine groups. Alternatively, a reversible H+-induced decrease in hydrophilicity was thus proposed. This contribution enriches the family of thermo-responsive polymers by introducing gas-sensitive polyelectrolytes and also broadens the scope of gas-responsive smart materials.

The isomerization reaction of pinene is one of the most important chemical reactions in the deep processing of pinene. The purpose of this study is to improve the performance of the metatitanic acid by composite. The composite metatitanic acid catalyst TiM was prepared by adding Mn elements in the preparation process. The catalytic performance of TiM was evaluated. Comparison of TiM and metatitanic acid catalyst (Ti-FGP), the reaction rate of TiM catalyst was faster, and after the reaction, the yield of camphene and tricyclene increased about 1%. The catalysts were characterized by an SEM, FT-IR and laser particle size analyzer. The results show that the pinene isomerization reaction requires the synergistic action of the Brӧnsted acid and Lewis acid. Brӧnsted acid has great influence on the activity of catalyst, and Lewis acid has a great influence on the selectivity of the catalyst. The structure and morphology of the catalyst have a certain effect on the selectivity of pinene isomerization reaction.

A well-controlled atom transfer radicfal polymerization of methyl acrylate (MA) was realized by mechanical mediation (mechanoATRP) in dimethyl sulfoxide (DMSO, 50% v/v). High conversions of typically over 90% were achieved. The resulting polymers had well-controlled molecular weights and very low dispersities (Đ = 1.03–1.09). No polymerization of MA was observed under various conditions from bulk up to 33.3% DMSO (v/v) solution. It was found that adding an equivalent volume of DMSO with respect to MA activated the polymerization. This finding suggested that DMSO played a crucial role in the mechanoATRP of MA. DMSO not only improved the solubility of CuBr2 complex but also facilitated an electron transfer process in the mechanical reduction of CuBr2. For a proof of the concept, a DMSO analogue acrylate, 2-(methylsulfinyl)ethyl acrylate (MSEA), was also polymerized. In addition, the high chain-end functionality of the polymers collected at ∼95% conversion was confirmed by 1H NMR, MALDI-ToF-MS, and in-situ c...

Metal-free atom transfer radical polymerization (ATRP) was successfully achieved in aqueous media for the first time. Polymerization of poly(ethylene oxide) methyl ether acrylate (PEGA480) was well controlled (Đ < 1.40) under visible light irradiation using tetrabromofluorescein (Eosin Y) as catalyst and pentamethyldiethylenetriamine (PMDETA) as electron donor. A validated kinetic model was developed to investigate the process of photoredox catalytic cycle via reductive quenching pathway. Experimental and simulation results showed that electron donor not only had an important influence on the ATRP activation, but also participated in the ATRP deactivation. Furthermore, the effects of water content, catalyst concentration, and degree of polymerization on the polymerization were studied thoroughly by a series of experiments. Good controllability of the polymerization regulated by light on and off confirmed the high degree of temporal control. The livingness of the chains was proved by a successful chain ext...

A challenge for the design of nonlinear polymerization is the full appreciation of the impact of side reactions, demanding the development of modeling techniques to determine the associated kinetic parameters while using the most important experimental responses. Here the combination of computationally inexpensive method of moments (MoM) kinetic simulations and dedicated principal component analysis (PCA) is put forward as a promising strategy to be successful in this respect. Focus is on (radical) vinyl grafting of chains containing unsaturations, selecting styrene (St) as monomer and polybutadiene (PB) as backbone, and low St conversions accounting for diffusional limitations on termination. It is highlighted that the less studied macropropagation cannot be directly ignored and a combined set of experimental responses related to free polystyrene and grafted copolymer (GC) average product properties is recommended for kinetic parameter estimation. This is supported by regression analysis considering in silico generated experimental data compensated for random noise and considering a validated end-chain approximation.

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 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.

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...

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.

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...

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...

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.

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.

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

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...

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.

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.

A series of thermal-responsive block copolymers, i.e., poly(methyl methacrylate)-block-poly(N-isopropylacrylamide) (PMMA-b-PNIPAAm), were successfully synthesized via successive copper(0)-mediated reversible-deactivation radical polymerization technology. Thermal properties of block copolymers with different PNIPAAm chain lengths were investigated by differential scanning calorimetery (DSC) and thermogravimetric analysis (TGA). The well-separated glass transition temperature values shown in DSC results indicate that two chemically different blocks, PNIPAAm and PMMA, are incompatible and phase-segregated. The thermal degradation results show that the thermal stability of these copolymers was improved through incorporating the PNIPAAm segments. The PMMA120-b-PNIPAAm86 and PMMA120-b-PNIPAAm130 maintain stability and undergo one-stage degradation when the temperature increases above 360 °C. Because of the synergistic effect of copolymer composition and copolymer film roughness, the obtained reversible thermal...

A comprehensive kinetic model based on the mechanism of supplemental activator and reducing agent atom transfer radical polymerization (SARA ATRP) was developed to better understand the kinetics of copper(0)-mediated reversible-deactivation radical polymerization [Cu(0)-mediated RDRP]. Simulation results show that diffusional limitation on termination significantly affects on polymerization. A comprehensive description of the variation trend of soluble species and reaction rates during polymerization was illustrated by simulation. The effects on kinetics of four key rate constants (i.e., ka0, kdisp, ka1, kcomp) involved in Cu(0)-mediated RDRP were investigated in detail, which contributed to greater insight into the differences between the SET-LRP and SARA ATRP mechanisms. Finally, Cu(0)-mediated RDRPs of methyl methacrylate (MMA) and butyl methacrylate (BMA) were conducted to study the polymerization kinetics at 25 °C. Results of simulations and experiments performed under polymerization conditions show ...

National Ministry of Science and Technology of China [2010CB226906, 2012CB215000, 2012CB21500402]; National Natural Science Foundation of China [21076171]; State Key Laboratory of Heavy Oil Processing (China University of Petroleum) [2012-1-08]

A kinetic model was developed for the atom transfer radical copolymerization (ATRcoP) of methyl methacrylate (MMA) and 2-(trimethylsilyl) ethyl methacrylate (HEMA-TMS) in tank reactors under three typical feeding modes, namely, batch, semibatch, and continuous feeding. The kinetic parameters for ATRcoP equilibrium were estimated from the model using the experiment data obtained under the batch mode. The simulation results were validated using the experimental data for the semibatch process. An excellent agreement between experiment and simulation data suggests that the model is suitable for simulating the copolymerization. The effects of different operating modes on the ATRcoP characteristics were investigated. The results demonstrated that each reactor possesses its own advantages and disadvantages. Furthermore, this study offers thorough polymerization characteristics comparison with the use of a constant ATRcoP system, and the results show a promising design in determining the optimal operating conditi...

A comprehensive model was developed using the method of moments to describe the atom transfer radical copolymerization (ATRcoP) of methyl methacrylate and 2-(trimethylsilyl) ethyl methacrylate in a train of continuous stirred-tank reactors (CSTRs). The use of a train of CSTRs effectively decreases the residence time distribution and molecular weight distribution. Two different constraint conditions (i.e., constant feeding flow rate and constant total average residence time) were simulated. At constant feeding flow rate, the monomer conversion and average molecular weight are significantly improved by increasing the number of CSTRs in the train. Moreover, a constant total average residence time increases the productivity of copolymers with the increase in the number of CSTRs in the series. Thus, a train of CSTRs can be used to produce copolymers continuously with consistent quality. This method is important in obtaining a balance between the quality and quantity of the copolymer production for ATRcoP. POLYM. ENG. SCI., 55:1030–1038, 2015. © 2014 Society of Plastics Engineers

A multi-scale CFD model has been developed to describe the particle behavior in a polyolefin fluidized bed reactor (FBR). The model consists of a CFD model incorporating a single particle model and a population balance model (PBM). The main particle behavior in the FBR can be calculated using the multi-scale model. The multi-scale model is tested by comparing simulation results with experimental data. Three cases including CFD coupled with PBM, CFD–PBM coupled with the single particle model without consideration of external diffusion, and multi-scale CFD model under consideration of external diffusion are developed to further examine the model. The simulations demonstrate that both intraparticle mass and heat transfers, which are ignored by these conventional CFD–PBM models, have significant effects on the particle behavior.

In order to quantitatively describe the pressure change during the copolymerization in industrial fluidized bed reactors, a dynamic reactor model was developed according to the mass and energy balances as well as real gas state-equation and copolymerization kinetics. Furthermore, in order to inspect the performance of pressure relief devices in response to the accident conditions, a set of pressure relief equations were also incorporated into the dynamic reactor model. Therefore, the extended reactor model is able to calculate the relief pressure besides other variables in the reactors such as temperature, slurry density and solid hold-up, which provides an important guidance for selecting pressure relief device and safe production. Dynamic data from certain industrial reactor were used to verify the above model. Finally, the application of the extended model was demonstrated by simulating several typical emergency accidents.

The origin of the low-energy emission of fluorene-based rod-coil block copolymers still remains controversial. In this work, a series of polyfluorene-based rod-coil block copolymers having different coil segments, i.e., poly[2,7-(9,9-dihexylfluorene)]-block-poly(2,2,3,3,4,4,4-heptafluorobutyl methacrylate, (PF-b-PHFBMA), PF-b-poly(butylmethacrylate) (PF-b-PBMA), PF-b-poly(2-hydroxyethyl methacrylate) (PF-b-PHEMA) and PF-b-poly(acrylic acid) (PF-b-PAA), were synthesized using the ATRP technique. The optical and surface properties and thermal behaviors of these copolymers were systematically investigated. In particular, different thermal treatment conditions, including annealing temperature, annealing time and annealing atmosphere were introduced to study the effect of coil segment on the copolymer spectral stability. The incorporation of PBMA, PHEMA and PAA segments to PF could indeed improve the copolymer spectral stability, while the PHFBMA block brought undesirable low-energy emission. In addition, water contact angle (WCA) measurements of the copolymer films before and after annealing further demonstrated that the low-energy emission of PF-based rod-coil block copolymers was attributed to the molecular aggregation rather than the formation of fluorenone defects.

Two improved multigrain models (MGMs) for preparing homopolypropylene and long chain branched polypropylene via propylene polymerization using silica-supported metallocene or dual function metallocene as catalysts are presented in this paper. The presented models are used to predict the intraparticle flow fields involved in the polymerizations. The simulation results show that the flow field distributions involve dare basically identical. The results also show that both the two polymerization processes have an initiation stage and the controlling step for them is reaction-diffusion-reaction with the polymerization proceeding. Furthermore, the simulation results show that the intra particle mass transfer resistance has significant effect on the polymerization but the heat transfer resistance can be ignored.

National Ministry of Science and Technology of China [2012CB21500402]; National Natural Science Foundation of China [21276213, 21076171]; State-Key Laboratory of Chemical Engineering of Tsinghua University [SKL-ChE-13A05]

National Ministry of Science and Technology of China [2012CB21500402]; Key Laboratory of Advanced Control and Optimization for Chemical Processes of the National Ministry of Education of China [2012ACOCP03]; National Natural Science Foundation of China [21076171, 21276213]

National Ministry of Science and Technology of China [2012CB21500402]; National Natural Science Foundation of China [21076171, 21276213]

National Ministry of Science and Technology of China [2012CB21500402]; National Natural Science Foundation of China [21076171, 21276213]; State Key Laboratory of Heavy Oil Processing (China University of Petroleum) [2012-1-08]

National Ministry of Science and Technology of China [2012CB21500402]; National Natural Science Foundation of China [21276213, 21076171]

National Ministry of Science and Technology of China [2012CB21500402]; National Natural Science Foundation of China [21076171]; State Key Laboratory of Heavy Oil Processing (China University of Petroleum) [2012-1-08]

National Natural Science Foundation of China [20406016, 21076171]; Nation Defense Key Laboratory of Ocean Corrosion and Anti-corrosion of China [51449020205QT8703]; Fujian Province Science and Technology Office of China [2005H040]

In this work, fluorinated nonamphiphilic gradient copolymers of tert-butyl acrylate (tBA) and 2,2,3,3,4,4,4-heptafluorobutyl methacrylate (HFBMA) [poly(tBA-grad-HFBMA)] were first synthesized by semibatch atom transfer radical copolymerization of tBA and HFBMA. Their hydrolysis at acidic conditions led to amphiphilic poly(acrylic acid-grad-HFBMA). The chemical compositions and structures of these copolymers were characterized by proton nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and gel permeation chromatography. Their surface properties were evaluated with water contact angle measurement and x-ray photoelectron spectroscopy. The micellization behaviors of amphiphilic copolymer were also studied by transmission electron microscopy and dynamic light scattering. The results showed that the fluorinated and amphiphilic gradient copolymers could self-assemble in a dilute solution to form aggregates of morphologies. Furthermore, the effect of pH on the aggregates was investigated to verify that the resulting gradient copolymers were to some extent pH sensitive. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

National Natural Science Foundation of China [21076171]; State-Key Laboratory of Chemical Engineering (Tsinghua University) [SKL-ChE-10A03]; Fujian Province Science and Technology Office of China [2009HZ0005-1]