Synthesis and Reactivity of Diazirine-Containing Polymers via Controlled Radical Polymerization

Huang, Banruo; Xu, Mizhi; Hawker, Craig J.

doi:10.1021/acs.macromol.4c00443

Cited by 4 publications

(2 citation statements)

References 46 publications

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“…On the other hand, diazo compounds are important carbene precursors and can readily participate in a variety of efficient organic transformations. − Notably, carbene chemistry based on diazo or its analogues has also been applied to post-polymerization modifications. − For example, the group of Rühe has developed a strategy for the formation of surface-attached polymer networks by designing polymethacrylates bearing diazomalonate cross-linker on the side chain . When activated under mild conditions, the cross-linker can be coated on the surface of different polymer materials by carbene C–H bond insertion.…”

Section: Introductionmentioning

confidence: 99%

Ring-Opening Polymerization of α-Diazo Lactones: Access to Diazo-Containing Polyesters and Their Post-Polymerization Modifications

Yu,

Wang,

Zhou

et al. 2024

Macromolecules

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The properties of polyesters can be enhanced by the introduction of various functional groups, while transformations of a diazo group via a carbene intermediate provide efficient approaches for functional group introduction. We herein report the first ring-opening polymerization (ROP) of 5, 6, and 7membered α-diazo lactones using t-BuOK as the initiator. The diazo groups can be well tolerated in the polymerization condition, leading to stable, diazo-containing polyesters that can be readily isolated and characterized. Post-polymerization transformations of the diazo groups, including [1,2]-hydrogen migration, Si−H insertions, and S−H insertions, further provide polyesters that are nontrivial to access. Further, the introduction of diazo groups generally increases the ring strain of lactones and alters their polymerizability, which is more pronounced for α-diazo γbutyrolactone. The ROP of α-diazo δ-valerolactone generates a new type of diazo-containing polyesters that can be depolymerized upon heating.

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Section: Introductionmentioning

confidence: 99%

Ring-Opening Polymerization of α-Diazo Lactones: Access to Diazo-Containing Polyesters and Their Post-Polymerization Modifications

Yu,

Wang,

Zhou

et al. 2024

Macromolecules

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“…Carbene-mediated polymer cross-linking employing rationally designed diazo-type carbene cross-linker precursors has also been reported recently. , Thermal decomposition generates the corresponding multifunctional carbenes to cross-link linear polymer chains by C–H insertion. Very recently, a platform based on diazirine polymers was developed for efficient cross-linking of C–H-containing polymers, such as poly(meth)acrylates . These examples, however, refer to permanently cross-linked polymers with a fixed topology.…”

mentioning

confidence: 99%

Exploiting the Reversible Dimerization of N-Heterocyclic Carbenes to Access Dynamic Polymer Networks with an Organocatalytic Activity

Abou-Ezze,

Llevot,

Taton

2024

ACS Macro Lett.

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The capability of some N-heterocyclic carbenes (NHCs) to reversibly dimerize is exploited to access dynamic polymer networks. Benzimidazolium motifs serving as NHC precursors have thus been supported onto copolymer chains by reversible addition–fragmentation chain transfer (RAFT) copolymerization of styrene and up to 20 mol % of 4-vinylbenzyl-ethyl-benzimidazolium chloride. Molecular versions of 1,3-dialkyl benzimidazolium salts have been synthesized as models, the deprotonation of which with a strong base yields the NHC dimers in the form of tetraaminoalkenes. The crossover reaction between two distinct NHC homodimers, forming heterodimers, is then evidenced. Applying this deprotonation method to the RAFT-derived copolymers leads to polymer networks with cross-links consisting of labile dimerized NHC motifs. These networks can be subsequently decross-linked using two distinct triggers, namely, a monofunctional NHC precursor as competitor and carbon dioxide (CO2). In the latter case, regeneration of the network occurs by chemically fueling the linear copolymer bearing benzimidazolium motifs with tBuOK in the presence of trace amounts of water. The same networks can also be used as latent precursors of transient polyNHCs to catalyze the benzoin condensation upon heating. The polymer-supported organocatalysts can thus be used in successive catalytic cycles.

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Design, Exploitation, and Rational Improvements of Diazirine-Based Universal Polymer Crosslinkers

Lepage,

Musolino,

Wulff

2024

Acc. Chem. Res.

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Metrics & MoreArticle Recommendations * sı Supporting Information CONSPECTUS: Addition of new covalent bonds between the chains of thermoplastic polymers (i.e., crosslinking) provides improved mechanical strength and enhanced high-temperature performance while also providing an effective strategy for photopatterning. Traditionally, however, crosslinking of each polymer substrate has required the use of a specific crosslinking technology (hydrosilylation for PDMS, vulcanization for rubber, etc.). The lack of a general solution to the challenge of polymer crosslinking means that there are many thermoplastics (e.g., polypropylene or polyhydroxyalkanoates) that have desirable properties, but which cannot be upgraded by traditional crosslinking technologies.Our lab developed the first universal crosslinkers for aliphatic polymers by leveraging trifluoromethyl aryl diazirine motifs, functional groups that have been widely used in chemical biology for >30 years, but which have seldom been exploited in materials science. These novel reagents work (via C−H insertion) on essentially any commodity polymer that contains aliphatic C−H bonds, including industrial plastics like polypropylene (the crosslinking of which has been an outstanding challenge in the field for >50 years), as well as commercially important elastomers (e.g., polydimethylsiloxane), biodegradable polymers (e.g., polycaprolactone), and green polymer materials derived from biomass (e.g., polyhydroxyalkanoates). Subsequent structure−function work from our group led to crosslinkers that were >10-fold more effective in undergoing C−H insertion with aliphatic substrates. We then developed an improved synthesis of our electronically optimized diazirines and incorporated them into a family of cleavable crosslinker reagents, which permit the on-demand generation of reprocessable thermosets. At the same time, other groups replaced the perfluoropropyl linker in our first-generation crosslinker with a series of dynamic linkages; these permit the ready generation of vitrimeric materials and can be used in the reactive compatibilization of immiscible plastic waste.Since the publication of our initial Science paper in 2019, this burgeoning field of diazirine-based polymer crosslinkers has experienced an explosion of interest. Publications from our lab and others have described the use of these reagents in covalent adhesion, photopatterning of low dielectric materials for microelectronics, and direct optical printing of quantum dots. Our crosslinkers have also been shown to heighten the robustness of ice-phobic coatings and improve the performance of woven ballistic fabric, while�perhaps most unexpectedly�substantially improving the stability of high-performance perovskite solar cells.Electronically optimized diazirines can also be used to covalently link proteins to polymer surfaces, suggesting a broad range of applications in the biocompatibilization of medical devices. This Account will summarize the development of trifluoromethyl aryl diazirine reagents for materials s...

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Synthesis and Reactivity of Diazirine-Containing Polymers via Controlled Radical Polymerization

Cited by 4 publications

References 46 publications

Ring-Opening Polymerization of α-Diazo Lactones: Access to Diazo-Containing Polyesters and Their Post-Polymerization Modifications

Ring-Opening Polymerization of α-Diazo Lactones: Access to Diazo-Containing Polyesters and Their Post-Polymerization Modifications

Exploiting the Reversible Dimerization of N-Heterocyclic Carbenes to Access Dynamic Polymer Networks with an Organocatalytic Activity

Design, Exploitation, and Rational Improvements of Diazirine-Based Universal Polymer Crosslinkers

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