Theoretical Analysis of the Copolymer Composition Equation in Chain Shuttling Copolymerization

Zhang, Min; Carnahan, Edmund M.; Karjala, Thomas W.; Jain, Pradeep

doi:10.1021/ma9018685

Cited by 24 publications

(36 citation statements)

References 10 publications

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“…[12,13] Because this approach cannot generate detailed microstructural distributions, Monte Carlo (MC) models were later developed for OBCs made in CSTRs operated at steadystate. [14][15][16] Subsequently, Mohammadi et al developed Chain-shuttling polymerization with dual catalysts has introduced a new class of polyolefins called olefin block copolymers (OBCs). A dynamic Monte Carlo model to describe the kinetics of chain-shuttling copolymerization in a semi-batch reactor is developed, and used it to study how the microstructure of OBCs with different numbers of blocks per chain evolves during polymerization.…”

mentioning

confidence: 99%

Understanding the Formation of Linear Olefin Block Copolymers with Dynamic Monte Carlo Simulation

Tongtummachat

Anantawaraskul

Soares

2016

Macro Reaction Engineering

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low comonomer reactivity ratio and produces high-crystallinity blocks (hard-blocks), while the other catalyst has high comonomer reactivity ratio and makes low-crystallinity blocks (soft-blocks). The CSA is the special component because it shuttles living polymer chains between the two catalysts, making chains with alternating hard and soft blocks. [1][2][3][4][5][6][7] OBCs have higher heat and abrasion resistances, and better processability than conventional polyolefin elastomers. [8][9][10][11] Because OBC may have many blocks, mathematical models are needed to quantify how polymerization conditions affect their microstructures. A detailed mathematical model describes how the complex OBC microstructure evolves during polymerization, providing useful insights on how to control these microstructures. Models for chain-shuttling polymerization in continuous stirred-tank reactors (CSTRs) were first developed using the method of moments to describe polymerization kinetics and average chain microstructures. [12,13] Because this approach cannot generate detailed microstructural distributions, Monte Carlo (MC) models were later developed for OBCs made in CSTRs operated at steadystate. [14][15][16] Subsequently, Mohammadi et al. developed Chain-shuttling polymerization with dual catalysts has introduced a new class of polyolefins called olefin block copolymers (OBCs). A dynamic Monte Carlo model to describe the kinetics of chain-shuttling copolymerization in a semi-batch reactor is developed, and used it to study how the microstructure of OBCs with different numbers of blocks per chain evolves during polymerization. The model also describes how chain-shuttling rate constants and concentration of chain-shuttling agent affect populations of OBCs with different numbers of blocks per chain. These model predictions are useful to make OBCs with precisely designed microstructures.

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mentioning

confidence: 99%

Understanding the Formation of Linear Olefin Block Copolymers with Dynamic Monte Carlo Simulation

Tongtummachat

Anantawaraskul

Soares

2016

Macro Reaction Engineering

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“…The copolymer composition directly reflects the chemical structure of polymers; thus, the composition equation is used to evaluate instantaneous composition of the bipolymers in light of the following formula [17,18].

F_{1} = \frac{r_{1} f_{1}^{2} + f_{1} f_{2}}{2 a}

F_{2} = 1 - \frac{(r_{1} - 1) {f_{2}}^{2} + (1 - 2 r_{1}) f_{2} + r_{1}}{(r_{1} - 2 + r_{2}) {f_{2}}^{2} + 2 (1 - r_{1}) f_{2} + r_{1}}

where F 1 and F 2 are the molar ratios of AM and cationic monomer to the total copolymer units, respectively; f 1 and f 2 are the molar ratios of AM and cationic monomer to all material monomers before polymerization, respectively; and r 1 and r 2 are the monomer reactivity ratios obtained from Section 2.3.…”

Section: Methodsmentioning

confidence: 99%

Improvement of Sludge Dewaterability by Ultrasound-Initiated Cationic Polyacrylamide with Microblock Structure: The Role of Surface-Active Monomers

et al. 2017

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Cationic polyacrylamides have been employed widely to improve sludge dewatering performance, but the cationic units are randomly distributed in the molecular chain, which restricts the further enhancement of dewaterability. Common template technology to prepare block copolymers requiring a huge number of templates reduces the polymer purity and molecular weight. Here, we adopted the surface-active monomer benzyl dimethyl 2-(methacryloyloxy)ethyl ammonium chloride (BDMDAC) to synthesize cationic microblocky polyacrylamide initiated by ultrasound. The reactivity ratio of monomers suggested that novel cationic monomer BDMDAC had higher homopolymerization ability, and was thus more prone to forming a microblock structure. The statistical analysis of sequence-length distribution indicated that the number and length of cationic segments increased in the PAB molecules. In addition, the characteristic results of Fourier transform infrared (FTIR), proton nuclear magnetic resonance (1H NMR), and thermogravimetric analysis (TGA) provided evidence for the synthesis of copolymer with cationic microblocks. Finally, the results of dewatering tests demonstrated that sludge dewaterability was greatly improved by adding the synthesized novel flocculants, and the sludge-specific resistance to filtration, filter cake moisture content and residual turbidity all reached a minimum (68.7%, 5.4 × 1012 m·kg−1, and 2.6 NTU, respectively) at 40 mg·L−1. The PAB flocs were large, compact, difficult to break, and easy to regrow. Furthermore, PAB was more effective in the removal of protein from soluble extracellular polymeric substances (SEPSs). In summary, this study provides a novel solution to synthesize cationic microblock polyacrylamide for improving sludge dewatering.

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“…Modeling studies reported so far were devoted to the analysis of copolymer composition, molecular weight distribution, length of the blocks, distribution of the number of blocks per chain and to finer microstructure analysis and its evolution during the polymerization . It has notably been shown that the Mayo − Lewis equation may no longer be able to describe the composition of the copolymers formed instantaneously by each catalyst in CSP systems operating in a continuous stirred tank reactor (CSTR) . This may arise when the chain transfer rate is substantially higher than the propagation rate, and may not be the case when a single catalyst is used in the presence of a chain transfer agent.…”

Section: Theoretical Modeling Of Cspmentioning

confidence: 99%

“…Steric hindrance as well as chain growth on the magnesium atom have been advanced to explain these effects. It should finally be noted that (i) several studies dealing with CCTcoP did not report significant changes in the copolymerization reactivity ratio and (ii) theoretical modeling in a CSTR does not predict such changes in the case of single catalyst/chain transfer agent mediated statistical copolymerization (CCTcoP).…”

Section: Unexpected Reactivities Observed In Coordinative Chain Transmentioning

confidence: 99%

Unexpected reactivities in chain shuttling copolymerizations

Zinck

2015

Polymer International

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Chain shuttling copolymerization (CSP) is a modern polymerization technique that allows in a one‐step procedure access to multiblock microstructures of statistical copolymer blocks of different compositions, providing notably new thermoplastic elastomers. The process involves the shuttling of a growing copolymeric chain between two catalysts showing different reactivity ratios versus the comonomers. The complexity of the active species formed in the presence of two catalysts and a chain transfer agent can give rise to unexpected reactivities. They are presented and discussed in this contribution, including their possible origin when provided and the consequences regarding the design of catalytic systems for CSP.

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Theoretical Analysis of the Copolymer Composition Equation in Chain Shuttling Copolymerization

Cited by 24 publications

References 10 publications

Understanding the Formation of Linear Olefin Block Copolymers with Dynamic Monte Carlo Simulation

Understanding the Formation of Linear Olefin Block Copolymers with Dynamic Monte Carlo Simulation

Improvement of Sludge Dewaterability by Ultrasound-Initiated Cationic Polyacrylamide with Microblock Structure: The Role of Surface-Active Monomers

Unexpected reactivities in chain shuttling copolymerizations

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