(swepub) lar1:(umu) pers:(Riboli Elio) pers:(Chirlaque Maria Dolores) pers:(Trichopoulou Antonia) pers:(Panico Salvatore) pers:(Agudo Antonio) pers:(Palli Domenico)
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Correlation between Polymerization Rate, Mechanism, and Conformer Thermodynamic Stability in Urea/Methoxide-Catalyzed Polymerization of Macrocyclic Carbonates
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- Huang, Jin (författare)
- KTH,Fiber- och polymerteknologi,Nanjing Tech Univ, Coll Biotechnol & Pharmaceut Engn, State Key Lab Mat Oriented Chem Engn, 30 Puzhu Rd South, Nanjing 211816, Peoples R China.
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- Dinér, Peter (författare)
- KTH,Organisk kemi
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- Nieboer, Vincent (författare)
- KTH,Polymerteknologi
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- American Chemical Society (ACS), 2023
- 2023
- Engelska.
- Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 56:18, s. 7496-7504
- Tidskriftsartikel (refereegranskat)
Abstract
Ämnesord
Stäng
- A combined experimental and theoretical investigation revealed mechanistic differences in the ring-opening polymerization (ROP) behavior of macrocyclic carbonates (MCs, 11-membered to 15-membered MCs). The study employs urea and potassium methoxide as the catalytic system for ROP. Besides the polymerization rate correlating with the ring size, where smaller rings have a faster polymerization rate, both the thermodynamic stability of the conformer and the stability of the transition state affect the polymerization rate. An experimental kinetic evaluation revealed a deviation between the polymerization rate of the 11-membered MC and the rest of the MCs. Computational investigation using density functional theory showed that the thermodynamic stability of the 11-membered MC differs from others, with a population distribution more toward the usually less energetically disfavored (E,Z)conformer, while the larger rings showed a preference for the Z,Z-conformation. In the transition state, the (E,Z)-conformer was found to be lower in energy compared to the (Z,Z)-conformation, which leads to a lower Gibbs free energy of activation for nucleophilic attack on the (E,Z)-conformation (Delta G(+/-) = 18.3 kcal center dot mol(-1)) compared to macrocycles with the more stable (Z,Z)-conformation (19.8 kcal center dot mol(-1)). The rate-determining step for the 11-membered MC with (E,Z)-conformation relates to the nucleophilic addition, while the rate-limiting step for the larger 15-membered MC corresponds to the ring-opening step. Linking the thermodynamic conformer stability of cyclic monomers to their inherent polymerization behavior is essential for the future design of selective catalysts for ROP.
Ämnesord
- TEKNIK OCH TEKNOLOGIER -- Kemiteknik -- Polymerteknologi (hsv//swe)
- ENGINEERING AND TECHNOLOGY -- Chemical Engineering -- Polymer Technologies (hsv//eng)
Nyckelord
- Carbonates
- Computation theory
- Conformations
- Density functional theory
- Free energy
- Gibbs free energy
- Metabolism
- Potassium compounds
- Ring opening polymerization
- Thermodynamic stability
- Urea
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- Huang, Jin
- Dinér, Peter
- Nieboer, Vincent
- Olsén, Peter
- Odelius, Karin
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