Modeling and semi-batch control of cross-link density distribution in the free-radical copolymerization of vinyl/divinyl monomers

Enright, Tom; Zhu, Shiping

doi:10.1002/(sici)1521-3919(20000401)9:4<196::aid-mats196>3.0.co;2-z

Cited by 9 publications

(1 citation statement)

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“…The calculated cross-linking density can be utilized to adjust the process operation. If the reaction kinetics are known, feeding of monomer and cross-linker in semibatch operation can be adjusted in order to achieve a homogeneous cross-linking distribution. , Hence, the process can be adapted to generate polymer with predefined properties.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Poly(N-vinylcaprolactam)-Based Microgels by Precipitation Polymerization: Process Modeling and Experimental Validation

Janssen

Kather

Kröger

et al. 2017

Ind. Eng. Chem. Res.

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The successful application of poly(N-vinylcaprolactam)-based microgels requires a profound understanding of their synthesis. For this purpose, a validated process model for the microgels synthesis by precipitation copolymerization with the cross-linker N,N′-methylenebis-(acrylamide) is formulated. Unknown reaction rate constants, reaction enthalpies, and partition coefficients are obtained by quantum mechanical calculations. The remaining parameter values are estimated from reaction calorimetry and Raman spectroscopy measurements of experiments with different monomer/cross-linker compositions. Because of high crosspropagation reaction rate constants, simulations predict a fast incorporation of the cross-linker. This agrees with reaction calorimetry measurements. Furthermore, the gel phase is predicted as the major reaction locus. The model is utilized for a prediction of the internal particle structure regarding its crosslink distribution. The highly cross-linked core reported in the literature corresponds to the predictions of the model.

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Section: Introductionmentioning

confidence: 99%

Synthesis of Poly(N-vinylcaprolactam)-Based Microgels by Precipitation Polymerization: Process Modeling and Experimental Validation

Janssen

Kather

Kröger

et al. 2017

Ind. Eng. Chem. Res.

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Crosslinking

Hernández‐Ortiz

Vivaldo‐Lima

2013

Handbook of Polymer Synthesis, Characterization, and Processing

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A Polymer‐Supported Chiral Fluorinated Dirhodium(II) Complex for Asymmetric Amination of Silyl Enol Ethers

et al. 2012

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The immobilization of dirhodium(II) tetrakis[N-tetrafluorophthaloyl-(S)-tert-leucinate], [Rh 2 A C H T U N G T R E N N U N G (S-TFPTTL) 4 ], has been accomplished by copolymerization of a dirhodium(II) complex-containing monomer with styrene and 1,6-bis(4-vinylbenzyloxy)hexane as a flexible cross-linker. The polymersupported chiral fluorinated dirhodium(II) complex catalyzed the amination of silyl enol ethers with [N-(2-nitrophenylsulfonyl)imino]phenyliodinane (NsN=IPh) to provide a-amino ketones in high yields with high levels of enantioselectivity and could be used up to 20 times as the catalyst readily withstood stirring in the presence of the solid reactant.Keywords: asymmetric catalysis; heterogeneous catalysis; immobilization; nitrenes; rhodium Chiral dirhodium(II) carboxylate and carboxamidate complexes are exceptional catalysts for a wide range of enantioselective metal carbene transformations with diazocarbonyl compounds, including cyclopropanation, C À H insertion, and rearrangement or cycloaddition via ylide generation.[1] Recently, they have also been recognized as effective catalysts in metal nitrene reactions such as C À H amination and olefin aziridination. [2][3][4][5][6][7][8] Although such reactions frequently proceed in high yield and with high levels of asymmetric induction, their practical applications in pharmaceutical production are hampered by the high costs of both rhodium [9] and chiral ligands as well as the difficulty in catalyst recovery and recycling. These drawbacks have stimulated a variety of efforts toward immobilization of chiral dirhodium(II) complexes.[10-16] While considerable advances have been made in selected catalytic asymmetric carbene processes, to the best of our knowledge, there is no immobilized dirhodium(II) catalyst available for nitrene reactions. [17,18] Recently, we reported an effective immobilization of [Rh 2 A C H T U N G T R E N N U N G (S-PTTL) 4 ] (1a) [19][20][21] (Figure 1), which was achieved by preparation of a dirhodium(II) complexcontaining monomer 2a followed by copolymerization with styrene (5a) and 1,6-bis(4-vinylbenzyloxy)hexane (6) as a flexible cross-linker (Scheme 1).[22-25] The polymer-supported complex 7a with no unreacted linkers or free ligands [26] catalyzed asymmetric C À H insertions with high enantioselectivities similar to those found with the homogeneous catalyst 1a and could be used for up to 100 sequential applications with a low leaching level.[22] Very recently, a similar method proved to be beneficial for the immobilization of a chiral chlorinated dirhodium(II) complex. [27] The immobilized catalyst 7b prepared by copolymerization of dirhodium(II) complex-containing monomer 2b with 2-(trifluoromethyl)styrene (5b) and crosslinker 6 (Scheme 1) was successfully applied to intermolecular carbonyl ylide cycloaddition reactions under continuous flow conditions, where high yields as well as high levels of enantioselectivity (up to 99% ee) and turnover number (up to 11,700) were achieved.[27] Given that catalysts 7a and 7b...

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Modeling and semi-batch control of cross-link density distribution in the free-radical copolymerization of vinyl/divinyl monomers

Cited by 9 publications

References 50 publications

Synthesis of Poly(N-vinylcaprolactam)-Based Microgels by Precipitation Polymerization: Process Modeling and Experimental Validation

Synthesis of Poly(N-vinylcaprolactam)-Based Microgels by Precipitation Polymerization: Process Modeling and Experimental Validation

Crosslinking

A Polymer‐Supported Chiral Fluorinated Dirhodium(II) Complex for Asymmetric Amination of Silyl Enol Ethers

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