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7. Combining Two Powerful Living Polymerizations Using Rationally Designed Bifunctional Initiators for Versatile Synthesis of Conjugated Rod–Coil Block Copolymers

Author

Choi, Hae-Nam, Yang, Hee-Seong, Park, Songyee, Choi, Tae-Lim, and Lee, In-Hwan

Abstract

Living polymerization has played a pivotal role in producing conjugated rod–coil block copolymers, offering a means to harness the functions of two distinct materials within nanoscale regions. Nevertheless, the accessibility of a diverse array of such copolymers has been restricted, primarily due to the lack of an efficient synthetic approach. To address this issue, we developed a bifunctional initiator approach that integrates two versatile living polymerizations: atom transfer radical polymerization (ATRP) and Suzuki–Miyaura catalyst-transfer polymerization (SCTP). This approach produces various conjugated rod–coil block copolymers with high precision, molecular weight control, low dispersity, and architecture control. Moreover, the one-pot synthesis of conjugated block copolymers was successfully demonstrated using consecutive photo-ATRP and SCTP. In addition, we systematically investigated the film morphology of the synthesized conjugated block copolymers by addressing the effects of the molecular weight, architecture, and regioisomeric linker units.

Published
2024
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17. Modular Access to Bifunctional Norbornenes and Their Application in Ring-Opening Metathesis Polymerization

Author

Denton, Elliott H., Cho, Minyoung, Morandi, Bill, and Choi, Tae-Lim

Abstract

A variety of exo-2,3-bifunctional norbornenes were prepared by the formal addition of C(aryl)–COCl bonds across norbornadiene using a palladium catalyst. The resulting exo-2,3-disubstituted norbornenes feature an aryl group and an acid chloride. Here, we trap the acid chloride in situ to prepare norbornenes with a methyl ester, a pentafluorophenyl ester, a sterically hindered secondary amide, and an N-methyl-N-methoxyamide (Weinreb amide). This modular strategy enabled the expedient preparation of a set of bifunctional monomers which were subjected to ring-opening metathesis polymerization with Grubbs first-generation catalyst. We show that the polymerization is compatible with a variety of aryl substituents including an azobenzene, a protected terminal alkyne, a boronic ester, and a furan. In addition, three monomers are subjected to polymerization at different M/I ratios and were found to give a near-linear increase in molecular weight. Furthermore, living polymerization was demonstrated by the successful preparation of block copolymers.

Published
2023
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19. Conformation Dynamics of Single Polymer Strands in Solution

Author

Bae, Yuna, primary, Ha, Min Young, additional, Bang, Ki‐Taek, additional, Yang, Sanghee, additional, Kang, Sung Yun, additional, Kim, Joodeok, additional, Sung, Jongbaek, additional, Kang, Sungsu, additional, Kang, Dohun, additional, Lee, Won Bo, additional, Choi, Tae‐Lim, additional, and Park, Jungwon, additional

Published
2022
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21. A scalable and continuous access to pure cyclic polymers enabled by quarantined heterogeneous catalysts

Author

Yoon, Ki-Young, Noh, Jinkyung, Gan, Quan, Edwards, Julian P., Tuba, Robert, Choi, Tae-Lim, Grubbs, Robert H., Yoon, Ki-Young, Noh, Jinkyung, Gan, Quan, Edwards, Julian P., Tuba, Robert, Choi, Tae-Lim, and Grubbs, Robert H.

Abstract

Cyclic polymers are topologically interesting and envisioned as a lubricant material. However, scalable synthesis of pure cyclic polymers remains elusive. The most straightforward way is to recycle a used catalyst for the synthesis of cyclic polymers. Unfortunately, it is demanding because of the catalyst’s vulnerability and inseparability from polymers, which depreciates the practicality of the process. Here, we develop a continuous process streamlined in a circular way that polymerization, polymer separation, and catalyst recovery happen in situ, to dispense a pure cyclic polymer after bulk ring-expansion metathesis polymerization of cyclopentene. It is enabled by introducing silica-supported ruthenium catalysts and a newly-designed glassware. Also, different depolymerization kinetics of the cyclic polymer from its linear analogue is discussed. This process minimizes manual labor, maximizes security of vulnerable catalysts, and guarantees purity of cyclic polymers, thereby showcasing a prototype of a scalable access to cyclic polymers with increased reusability of precious catalysts (≥415,000 turnovers).

Published
2022

22. Depolymerization of poly(α‐methyl styrene) with ball‐mill grinding.

Author

Jung, Eunsong, Yim, Daniel, Kim, Hyungjun, Peterson, Gregory I., and Choi, Tae‐Lim

Subjects
DEPOLYMERIZATION, VINYL polymers, CHAIN scission, STYRENE, THERMODYNAMIC control
Abstract

The development of mild methods to depolymerize polymers has become increasingly important in our current Age of Plastics, and ball‐mill grinding (BMG) is emerging as a promising candidate. In this report, we demonstrate that subjecting poly(α‐methyl styrene) (PMS) to BMG leads to high extents of depolymerization (up to 64 mol% of α‐methyl styrene was produced) with minimal side products after only minutes of grinding. Constrained geometries simulate external force (CoGEF) simulations and radical trapping experiments supported that the depolymerization was initiated by mechanochemical chain scission. Depolymerization proceeded despite bulk temperatures remaining far below that of the ceiling temperature of PMS. Control experiments suggested that the extent of depolymerization was equilibrium controlled. Polystyrene and poly(methyl methacrylate) also underwent depolymerization, although to a much lesser degree (up to 4% monomer produced), presumably due to their much higher ceiling temperatures. This work provides an entry point for further development of BMG as a tool for the depolymerization of vinyl polymers under mild conditions. [ABSTRACT FROM AUTHOR]

Published
2023
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27. A scalable and continuous access to pure cyclic polymers enabled by quarantined heterogeneous catalysts

Author

Yoon, Ki-Young, Noh, Jinkyung, Gan, Quan, Edwards, Julian, Tuba, Robert, Choi, Tae-Lim, and Grubbs, Robert H.

Subjects
Synthetic Process, Olefin Metathesis, Catalyst Recycling, Heterogeneous, Cyclic polymers, Polymerizations, Depolymerization, Polymer topology, Catalysis
Abstract

Cyclic polymers are topologically interesting and envisioned as a lubricant material. However, scalable synthesis of pure cyclic polymers remains elusive. The most straightforward way is to recycle a used catalyst for the synthesis of cyclic polymers. Unfortunately, it is demanding because of the catalysts vulnerability and inseparability from polymers, which depreciates the practicality of the process. Here, we develop a continuous process streamlined in a circular way that polymerization, polymer separation, and catalyst recovery happen in situ, to dispense a pure cyclic polymer after bulk ring-expansion metathesis polymerization of cyclopentene. It is enabled by introducing silica-supported ruthenium catalysts and a newly-designed glassware. Also, different depolymerization kinetics of the cyclic polymer from its linear analogue is discussed. This process minimizes manual labor, maximizes security of vulnerable catalysts, and guarantees purity of cyclic polymers, thereby showcasing a prototype of a scalable access to cyclic polymers with increased reusability of precious catalysts (415,000 turnovers)., ChemRxiv

Published
2021

33. Tandem diaza-Cope rearrangement polymerization: turning intramolecular reaction into powerful polymerization to give enantiopure materials for Zn₂₊ sensors

Author

Hwang, Soon-Hyeok and Choi, Tae-Lim

Abstract

[3,3]-Sigmatropic rearrangement is a powerful reaction to form C-C bonds stereospecifically; however, owing to intrinsic simultaneous bond formation and breakage, this versatile method has not been utilized in polymerization. Herein, we report a new tandem diaza-Cope rearrangement polymerization (DCRP) that can synthesize polymers with defect-free C-C bond formation from easy and efficient imine formation. A mechanistic investigation by in situ 1H NMR experiments suggests that this polymerization proceeds by a rapid DCR process, forming an enantiospecific C-C bond that occurs almost simultaneously with imine formation. This polymerization produces not only highly stable polymers against hydrolysis due to resonance-assisted hydrogen bonds (RAHBs) but also chiral polymers containing enantiopure salen moieties, which lead to high-performance Zn2+-selective turn-on chemosensors with up to 73-fold amplification. We also found that their optical activities and sensing performances are heavily dependent on the reaction temperature, which significantly affects the stereoselectivity of DCR., Chemical Science, 12 (7), ISSN:2041-6520, ISSN:2041-6539

Published
2021
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37. Recent Advances in Diversity‐Oriented Polymerization Using Cu‐Catalyzed Multicomponent Reactions.

Author

Lee, In‐Hwan, Bang, Ki‐Taek, Yang, Hee‐Seong, and Choi, Tae‐Lim

Subjects
POLYMERIZATION, POLYMER structure
Abstract

Diversification of polymer structures is important for imparting various properties and functions to polymers, so as to realize novel applications of these polymers. In this regard, diversity‐oriented polymerization (DOP) is a powerful synthetic strategy for producing diverse and complex polymer structures. Multicomponent polymerization (MCP) is a key method for realizing DOP owing to its combinatorial features and high efficiency. Among the MCP methods, Cu‐catalyzed MCP (Cu‐MCP) has recently paved the way for DOP by overcoming the synthetic challenges of the previous MCP methods. Here the emergence and progress of Cu‐MCP, its current challenges, and future perspectives are discussed. [ABSTRACT FROM AUTHOR]

Published
2022
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