Bimetallic Chromium Catalysts with Chain Transfer Agents: A Route to Isotactic Poly(propylene oxide)s with Narrow Dispersities

Morris, Lilliana S.; Childers, M. Ian; Coates, Geoffrey W.

doi:10.1002/anie.201801380

Cited by 43 publications

(38 citation statements)

References 35 publications

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“…In these prior ROCOP studies the formation of ether linkages or blocks was not observed but the reactions were conducted with equivalent epoxide:anhydride loadings which would prevent observation of epoxide ROP following the alternating enchainment. Additionally, related bimetallic Cr-salen complexes were effective stereoselective propene oxide ROP catalysts, suggesting that under proper conditions the catalysts might be able to enchain polyether blocks 34,35 . It is also worth commenting that previously, [SalcyCrCl] was used in switchable polymerizations of cyclohexene oxide (CHO)/ anhydrides/decalactone to selectively produce poly(ester- b -ester’) without any evidence of ether blocks or linkages.…”

Section: Resultsmentioning

confidence: 99%

Easy access to oxygenated block polymers via switchable catalysis

et al. 2019

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Oxygenated block polyols are versatile, potentially bio-based and/or degradable materials widely applied in the manufacture of coatings, resins, polyurethanes and other products. Typical preparations involve multistep syntheses and/or macroinitiator approaches. Here, a straightforward and well-controlled one-pot synthesis of ABA triblocks, namely poly(ether- b -ester- b -ether), and ABCBA pentablocks, of the form poly(ester- b -ether- b -ester’- b -ether- b -ester), using a commercial chromium catalyst system is described. The polymerization catalysis exploits mechanistic switches between anhydride/epoxide ring-opening copolymerization, epoxide ring-opening polymerization and lactone ring-opening polymerization without requiring any external stimuli. Testing a range of anhydrides, epoxides and chain-transfer agents reveals some of the requirements and guidelines for successful catalysis. Following these rules of switch catalysis with multiple monomer additions allows the preparation of multiblock polymers of the form (ABA) n up to 15 blocks. Overall, this switchable catalysis delivers polyols in a straightforward and highly controlled manner. As proof of potential for the materials, methods to post-functionalize and/or couple the polyols to make higher polymers are demonstrated.

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Section: Resultsmentioning

confidence: 99%

Easy access to oxygenated block polymers via switchable catalysis

et al. 2019

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“…Additionally, other catalysts exposed to mixtures of PO/LA yielded either only isotactic PLA or formed 3,6‐dimethyl‐1,4‐dioxan‐2‐one (lactone) . Other side reactions could be PO ring‐opening polymerisation (ROP) to polyethers and/or unselective ring‐opening copolymerisation (ROCOP) to form poly(ether‐ester)s . Overall, these particular monomers bring additional complexities and potential side reactions compared to previous studies, and these problems must be overcome for successful switch catalysis.…”

Section: Methodsmentioning

confidence: 99%

Switch Catalysis To Deliver Multi‐Block Polyesters from Mixtures of Propene Oxide, Lactide, and Phthalic Anhydride

2018

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Switchable polymerisation catalysis enables block polymer sequence selectivity from monomer mixtures, resulting in the formation of multiblock polyesters. The aluminium salphen catalyst switches between two different polymerisation mechanisms and selectively enchains mixtures of commercially available monomers: lactide, phthalic anhydride, and propene oxide. Sequential monomer mixture additions yield multi‐block polyesters featuring 3, 7, 11, 15, 19, 23, and 27 blocks. The unparalleled catalytic selectivity can be used to access completely new multi‐block polyesters relevant for future applications.

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“…To address these shortcomings, numerous catalytic strategies have been reported for epoxide polymerizations. Catalytic methods can result in polymers and also copolymers , with high molecular weight, narrow dispersity, − and controlled stereochemistry. − However, the catalyst synthesis in these methods can be complex and/or use expensive starting materials, making them less suitable for nonexperts that may want to utilize polyether materials.…”

Section: Introductionmentioning

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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Bimetallic Chromium Catalysts with Chain Transfer Agents: A Route to Isotactic Poly(propylene oxide)s with Narrow Dispersities

Cited by 43 publications

References 35 publications

Easy access to oxygenated block polymers via switchable catalysis

Easy access to oxygenated block polymers via switchable catalysis

Switch Catalysis To Deliver Multi‐Block Polyesters from Mixtures of Propene Oxide, Lactide, and Phthalic Anhydride

Aluminum-Based Initiators from Thiols for Epoxide Polymerizations

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