Ultrahigh-Molecular-Weight Poly(propylene oxide): Preparation and Perspectives

Walther, Patrick; Vogler, Charlotte; Naumann, Stefan

doi:10.1055/s-0039-1690778

Cited by 9 publications

(14 citation statements)

References 18 publications

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“…Similar molecular weight control was demonstrated for polymerizations of propylene oxide (PO) and butylene oxide (BO). PO and BO are difficult to polymerize via traditional methods (i.e., AROP) to even moderate molecular weights (i.e., M n > 10 kg/mol) due to their propensity to chain transfer, but work by several different researchers like Carlotti, Deffieux, Naumann, and Coates over the past 2 decades have demonstrated the high-molecular-weight synthesis of PPO by other means. However, high molecular PBO still remains a challenge.…”

Section: Resultsmentioning

confidence: 99%

Aluminum-Based Initiators from Thiols for Epoxide Polymerizations

Safaie

Rawal²,

Ohno

et al. 2020

Macromolecules

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We present a new method for epoxide polymerizations utilizing aluminum-based initiators, which leverage the chemical versatility of thiol compounds to control the polymer end group. The homo- and co-polymerization of various epoxides, such as epichlorohydrin and propylene oxide, demonstrate the flexibility of the initiators. Polymer molecular weight was controlled up to 100 kg/mol for the epoxides studied while maintaining relatively narrow dispersity (Đ < 1.4). We further characterized the kinetics of epoxide polymerizations through 1H NMR spectroscopy and studied how the initiator structure impacted the kinetics. Finally, we employed our initiators to polymerize from thiol end-functionalized poly(methyl methacrylate) (PMMA) synthesized through reversible addition fragmentation chain transfer (RAFT) polymerization, which allows us to easily create block copolymers made from vinyl and epoxide monomers. Therefore, this new synthetic tool allows for the facile polymerization of epoxides into well-defined, functional, polyether materials.

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Section: Resultsmentioning

confidence: 99%

Aluminum-Based Initiators from Thiols for Epoxide Polymerizations

Safaie

Rawal²,

Ohno

et al. 2020

Macromolecules

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“…Z-LPP of lactones initiates by attack on an activated lactone monomer by a LB, followed by ring-opening of the lactone to an LA-stabilized alkoxide. Z-LPP has been utilized to effect polymerization of lactides, − lactones, ,,,− epoxides, ,,− and cyclic carbonates . This method is highly selective, especially where maintenance of stereocenters is of concern (such as lactides and ring-fused bicyclic lactones) and when cyclic topologies are desired.…”

Section: Mechanismmentioning

confidence: 99%

Lewis Pair Polymerization: Perspective on a Ten-Year Journey

2020

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Ten years have passed since the conception of what was termed Lewis pair polymerization (LPP) that employs Lewis acid and base in pairs to not only activate monomers but also effect chain initiation, propagation, and transfer events. Compared to other polymerization methodologies, LPP's cooperative and synergistic two-component catalytic mechanism empowers several unique or advantageous features, including extraordinary tunability of catalyst/ initiator systems, compounded thermodynamic and kinetic control over comonomer sequences in one-pot LPP of monomer mixtures for highly resolved block copolymers, complete chemoselectivity in LPP of multifunctional vinyl monomers, independent tuning of polymerization activity and target polymer molecular weight, controlled heat dissipation in bulk polymerization with unactivated monomers functioning as solvent molecules, and coupled selectivity and livingness with immortality of the active species to produce ultrahigh molecular weight polymers and block copolymers with record-number (53) blocks. Focusing on four fundamental attributes of any polymerization methodologymechanism, kinetics, control, and selectivitythis Perspective narrates the growth and development of LPP, tracing each innovation back to fundamental principles so that each concept can be strategically applied, and describes new frontiers fertile for future research.

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“…The residual Al-based compound was found to activate the epoxide, leading to the polymerization in mild conditions. Following this approach, several dual catalysts based on the association of moderate organic bases and different Lewis acids revealed high efficiency in the polymerization of epoxides [26][27][28][29][30]. In this article we present that the combination of a NHC with i-Bu 3 Al improves the NHC's efficiency for propylene oxide.…”

Section: Introductionmentioning

confidence: 92%

N-Heterocyclic carbene/Lewis acid-mediated ring-opening polymerization of propylene oxide. Part 1: Triisobutylaluminum as an efficient controlling agent

Song

Zhao

Zhang

et al. 2020

European Polymer Journal

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Ring-opening polymerization (ROP) of propylene oxide (PO) is achieved at 25 °C either in bulk or in solution, using N-heterocyclic carbenes (NHCs) and triisobutylaluminum (i-Bu 3 Al) as a bicomponent catalytic system. Transfer to monomer was not observed and poly(propylene oxide)s with predictable molar masses up to 60 000 g.mol -1 and low dispersities were obtained. In presence/absence of an alcohol as the initiator, the polymerization of PO follows anionic or zwitterionic ROP mechanisms, respectively. The addition of the Lewis acid strongly improves the efficiency of NHCs for the polymerization of substituted epoxides. It is established that i-Bu 3 Al is involved both in the formation of an initiating/propagating complex of moderate basicity/nucleophilicity and in the coordination of PO, enabling the activation of the monomer towards the complexed nucleophilic active species. Block copolyethers are also prepared by PPO chain extension experiments. All (co)polyethers were thoroughly characterized by 1 H NMR spectroscopy, SEC and MALDI-TOF mass spectrometry as means to prove the control and benefit of this NHC approach for epoxides ROP.

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Ultrahigh-Molecular-Weight Poly(propylene oxide): Preparation and Perspectives

Cited by 9 publications

References 18 publications

Aluminum-Based Initiators from Thiols for Epoxide Polymerizations

Aluminum-Based Initiators from Thiols for Epoxide Polymerizations

Lewis Pair Polymerization: Perspective on a Ten-Year Journey

N-Heterocyclic carbene/Lewis acid-mediated ring-opening polymerization of propylene oxide. Part 1: Triisobutylaluminum as an efficient controlling agent

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