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The quantification of dispersity is an indispensable part of characterizing polymers. In this work, general dispersity equations for “living” polymers obtained by nitroxide-mediated polymerization ...

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.

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.

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 past decades have witnessed an increasing interest in developing advanced polymerization techniques subjected to external fields. Various physical modulations, such as temperature, light, electricity, magnetic field, ultrasound, and microwave irradiation, are noninvasive means, having superb but distinct abilities to regulate polymerizations in terms of process intensification and spatial and temporal controls. Gas as an emerging regulator plays a distinctive role in controlling polymerization and resembles a physical regulator in some cases. This review provides a systematic overview of seven types of external-field-regulated polymerizations, ranging from chain-growth to step-growth polymerization. A detailed account of the relevant mechanism and kinetics is provided to better understand the role of each external field in polymerization. In addition, given the crucial role of modeling and simulation in mechanisms and kinetics investigation, an overview of model construction and typical numerical methods used in this field as well as highlights of the interaction between experiment and simulation toward kinetics in the existing systems are given. At the end, limitations and future perspectives for this field are critically discussed. This state-of-the-art research progress not only provides the fundamental principles underlying external-field-regulated polymerizations but also stimulates new development of advanced polymerization methods.

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...

Suspension polymerization of methyl methacrylate (MMA) has been considered as a liquid–liquid reactive polydispersity system, which involves the complex multiphase flow behavior at multiple time and length scales. The polymerization kinetic characteristics (i.e., gel effect and glass effect) and liquid–liquid dispersion phenomena (i.e., breakage and coalescence of liquid droplets) appearing in this process make the study of suspension polymerization complicate. In this work, a three dimensional (3D) multiscale model including Eulerian–Eulerian two-fluid model, polymerization kinetics model, population balance model (PBM) and some other constitutive models was developed to elaborate those multiscale phenomena in polymerization course. The current model was validated using the reported data in terms of conversion, molecular weight as well as droplet Sauter diameter. The developed model was then employed to investigate the influence of key operating conditions on polymerization kinetic characteristics and liquid–liquid dispersion phenomena. Furthermore, the effects of reactor structure on droplet breakage and coalescence were studied in detail. This simulation work may contribute to the preparation of polymer products and the scaling up of stirred tank polymerization reactors with multiphase flow and multiscale characteristics.

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...

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...

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.

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...

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.

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.

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.

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

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

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.

Poly(methyl methacrylate)-block-poly(4-vinylpyridine), polystyrene-block-poly(4-vinyl pyridine), and poly(ethylene glycol)-block-poly(4-vinylpyridine) block copolymers are synthesized by successive atom transfer radical polymerization (ATRP), single-electron-transfer nitroxide-radical-coupling (SET-NRC) and nitroxide-mediated polymerization (NMP). This paper demonstrates that this new approach offers an efficient method for the preparation of 4-vinylpyridine-containing copolymers.

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 ...

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 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.

An Eulerian–Eulerian two-fluid coupling the population balance model (PBM) is developed to describe the gas–solid two-phase flow in a multizone circulating polymerization reactor (MZCR). The polymerization kinetics is also incorporated into the coupled model by using a user-defined function (UDF). The model is first used to predict the entire field in the MZCR with considering the polydispersity of solid phase. Furthermore, the temperature field is obtained numerically with considering polymerization reaction, and the effect of inlet gas temperature on the temperature field is also investigated. Finally, the model is adopted to distinguish between the flow behaviors in a circulating fluidized bed reactor (CFBR) and a MZCR. The simulated results show that the flow behavior in the MZCR with polydisperse solid phase is different from that with uniform particle size and the inlet gas temperature has great effects on the temperature distribution. Moreover, the simulation results also show that the differences in between CFBR and MZCR are mainly embodied in the temperature distribution.

National Natural Science Foundation of China [21076171]; National Ministry of Science and Technology of China [2012CB21500402]; State-Key Laboratory of Chemical Engineering of Tsinghua University [SKL-ChE-10A03]

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

National Natural Science Foundation of China[21076171]; China National Petroleum Corporation

National Natural Science Foundation of China[21076171]; China National Petroleum Corporation

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

National Natural Science Foundation of China [21076171]; State-Key Laboratory of Chemical Engineering of Tsinghua University [SKL-ChE-10A03]; China National Petroleum Corporation

National Natural Science Foundation of China[21076171]; State Key Laboratory of Chemical Engineering of Tsinghua University[SKL-ChE-10A03]; China National Petroleum Corporation

National Natural Science Foundation of China[20406016, 21076171]; China National Petroleum Corporation

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]

A coupled-single-particle and Monte Carlo model was used to simulate propylene polymerization. To describe the effects of intraparticle transfer resistance on the polymerization kinetics, the polymeric multilayer model (PMLM) was applied. The reaction in each layer of the PMLM was described with the Monte Carlo method. The PMLM was solved together with the Monte Carlo model. Therefore, the model included the factors of the mass- and heat-transfer resistance as well as the stochastic collision nature of the polymerization catalyzed with single-site-type/multiple-site-type catalysts. The model presented results such as the polymerization dynamics, the physical diffusion effect, and the polymer molecular weight and its distribution. The simulation data were compared with the experimental/actual data and the simulation results from the uniform Monte Carlo model. The results showed that the model was more accurate and offered deeper insight into propylene polymerization within such a microscopic reaction–diffusion system. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

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

Well-defined poly(dimethylsiloxane)-b-poly(2,2,3,3,4,4,4-heptafluorobutyl methacrylate-b-poly(styrene) (PDMS-b-PHFBMA-b-PS) triblock copolymers were prepared by two-step reversible addition-fragmentation chain transfer (RAFT) polymerization. The two-step RAFT polymerization proceeded in a controlled manner as demonstrated by the macromolecular characteristics of the blocks and corresponding polymerization kinetic data. Furthermore, surface properties and morphologies of the polymers were investigated with static water contact angle (WCA) measurement, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and atomic force microscopy (AFM) which showed low surface energy and microphase-separation surfaces.

National Natural Science Foundation of China [National Natural Science Foundation of China (Grant 20406016]; China National Petroleum Corp.

National Natural Science Foundation of China [20406016]; Fujian Petrochemical Company of SINOPEC

A comprehensive model was developed for the PSD of PP produced in loop reactors. The polymeric multilayer model (PMLM) was first applied to calculate the single particle growth rate under intraparticle transfer limitations. In order to obtain the comprehensive model, the PMLM was solved together with a steady-state particle population equation to predict the PSD in the loop reactors. The simulated PSD data obtained under steady-state polymerization conditions agreed with the actual data collected from industrial scale plant. The comprehensive model was also used to predict the effects of some critical factors, including the intraparticle mass and heat transfer limitations, the feed catalyst particle size and the catalyst deactivation, etc., on the PSD.

Both steady-state and dynamic models for the commercial bulk polypropylene process of HYPOL technology were developed by using fundamental chemical engineering principles and advanced software tools, Polymers Plus and Aspen Dynamics. The models consider the important issues of physical property and thermodynamic model selections, catalyst characterization, and reactor model, in addition to the traditional Ziegler–Natta polymerization kinetics. The performance of equilibrium-stage modeling was examined using the perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state and a pre-built reactor model in Polymers Plus. The detection of non-equilibrium behavior for the liquid-phase reactor leads to a novel reactor model suggested in this work, wherein the vapor–liquid equilibrium behavior was separated from polymerization behavior. Besides, the traditional Ziegler–Natta polymerization system was incorporated from single-site to multi-site model by fitting the actual data sourced from open reports and certain plant data. Furthermore, we validated the models using the plant data and demonstrated the application of our dynamic model by simulating a grade change.

A comprehensive steady-state population balance model is developed for the particle size distribution (PSD) of the polypropylene produced in tubular loop reactors. The model considers the flow type, the polymer particle dynamics, the particle growth and the attrition. Moreover, an empirical single particle model is used to describe the particle growth under internal and external heat and mass transfer limitations totally. The predicted PSD data obtained under steady-state polymerization conditions agree well with the actual data collected from industrial scale plant. The model are also used to predict the effects of some operational parameters on the polymer PSD produced under steady-state conditions. The results show that the polymer PSD are greatly affected by the feed catalyst size, the feed catalyst PSD, and the polymerization temperature.

In the present study, propylene polymerization using a solid Ziegler–Natta catalyst in a loop reactor is described on the basis of a polymeric multilayer model. The simulated results obtained by using the polymeric multilayer model are found to be in agreement with reference results obtained by using a multigrain particle model. In addition, the effect of the polymerization rate on the intraparticle mass and heat transfer is investigated by considering the polymeric multilayer model and the dependence of the intraparticle monomer concentration and temperature profiles on the polymerization rate is examined.