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Precise control over sequence structure in copolymers is essential for chemical product engineering. The complexity of sequence structures results in the challenging characterization of monomer sequences. Herein, a chemical composition model (CD model) is developed to record the distribution density of monomers in the chain segment, where the deviation of the chemical composition function between a copolymer and its ideal sequence structure can directly map the sequence structure quality. The application of the CD model in randomly generated virtual copolymers demonstrates that the model has great sensitivity and discrimination to evaluate sequence structures accurately. Furthermore, the CD model is combined with the kinetic Monte Carlo algorithm to explicitly track the evolution of sequence structure quality in the copolymerization process. The CD model provides an insight into the evolution of sequence structure, which is conducive to building the bridge between molecular structure and properties for the development of chemical product engineering. [ABSTRACT FROM AUTHOR]

A challenge for high‐impact polystyrene (HIPS) production and design is the more accurate and low computational cost prediction of the phase separation and phase inversion conversion, the first conversion determining the onset of the two‐phase system and the second conversion defining the pathway toward a complex, for example, salami‐like morphology. In this work, a two‐phase deterministic method of moments (MoM) model running in several minutes is therefore developed in the intermediate styrene conversion range (up to around 30%), considering for simplicity only diffusional limitations on termination on an average basis. It is showcased that the phase separation conversion can be taken as 2 m%, and the phase inversion conversion should be calculated by algebraic means. Interestingly, the latter conversion varies with the initial reaction conditions either on a time basis (e.g., variation of initial radical concentration) or both a time and conversion basis (e.g., relative contribution of rubber and St partitioning coefficient). A comparison with the commonly used pseudo‐homogeneous MoM model reveals that by accounting for mass transfer in a more representative two‐phase model, the amount of monomer consumed is slightly reduced, the grafting efficiency decreases with increasing conversion instead of increasing, and the styrene composition in the graft copolymer decreases. The current work additionally puts forward two‐phase MoM data to facilitate future benchmarking with other (stochastic) modeling approaches and enables kinetic insights into heterogeneous grafting polymerization, further promoting the production of multiphase industrial polymer products. [ABSTRACT FROM AUTHOR]

More and more attention has been paid to the important roles of external fields in controlled radical polymerization (CRP). However, their essential roles have not been studied thoroughly yet, which hinders the in‐depth understanding of the mechanism and kinetics. Herein, a strategy combining quantum chemical calculations (QCC) and kinetic modeling was adopted to identify the essential roles of light and ultrasonication in the dual‐stimuli regulated bulk atom transfer radical polymerization (ATRP). At the molecular level, the impact of light on Cu‐catalyzed ATRP was investigated. The CuIIBr/Me6TREN has high absorbance at an experimental wavelength of 365 nm (main excitation S0 → D7 accounts for 84.93%). Electron transfer reactions involving Me6TREN are more favorable paths for photochemical reactions, and the mechanism of the copper activation/deactivation pathway is inner sphere electron transfer. At the micro‐scale, a kinetic model based on the method of moment was established with a "series" encounter pair model to consider the influence of ultrasound on diffusional limitation. Simulation results show that the changes of the reaction rate coefficients ka, kda, and kt at high conversion reflect the degree of diffusional limitation by ultrasound. The multiscale modeling strategy applied in this study identifies the essential roles of photo and ultrasonication in dual‐stimuli regulated model systems, which can be extended to other external‐field regulated CRP to improve the mechanistic understanding. [ABSTRACT FROM AUTHOR]

In the present study, a combined kinetic and heat transfer model was developed to study the kinetics and predict thermal runaway of vinyl chloride (VC) suspension polymerization. Reactor temperature, monomer conversion, mole of initiator, radical concentrations in the two phases (i.e., VC‐rich phase and PVC‐rich phase), and average molecular properties were mapped during non‐isothermal processes. Meanwhile, the risk of thermal runaway was evaluated using S–Z (divergence) and H–J criteria. Simulation results show that a lower jacket temperature Tj and a larger heat transfer coefficient U are able to postpone or even avoid the risk of thermal runaway. Both of the criteria serve well for the prediction of thermal runaway during non‐isothermal processes. To prevent the occurrence of thermal runaway to the greatest extent, model‐based design of strategies for an isothermal polymerization process was done. Specifically, either jacket temperature Tj or heat transfer coefficient U can be fine‐tuned to maintain a 50°C isothermal process. [ABSTRACT FROM AUTHOR]

Photocatalytic hydrogen (H2) production is significant to overcome challenges like fossil fuel depletion and carbon dioxide emission, but its efficiency is still far below that which is needed for commercialization. Herein, we achieve long‐term stable H2 bubbling production from water (H2O) and lactic acid via visible‐light‐driven photocatalysis in a porous microreactor (PP12); the catalytic system benefits from photocatalyst dispersion, charge separation, mass transfer, and dissociation of O−H bonds associated with H2O. With the widely used platinum/cadmium‐sulfide (Pt/CdS) photocatalyst, PP12 leads to a H2 bubbling production rate of 602.5 mmol h−1 m−2, which is 1000 times higher than that in a traditional reactor. Even when amplifying PP12 into a flat‐plate reactor with an area as large as 1 m2 and extending the reaction time to 100 h, the H2 bubbling production rate still remains at around 600.0 mmol h−1 m−2, offering great potential for commercialization. [ABSTRACT FROM AUTHOR]