{ "id": "epgmenasvn", "slug": "click-polymerization", "title": "Click polymerization", "updated": "2026-10-21", "topic_path": [ { "id": "physical", "label": "Physical world and mathematics", "api_url": "https://www.edgepedia.org/api/v1/topics/physical" }, { "id": "physical.chemistry", "label": "Chemistry", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry" }, { "id": "physical.chemistry.methods", "label": "Chemical principles and methods", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry.methods" }, { "id": "physical.chemistry.methods.chemical-synthesis", "label": "Chemical synthesis", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry.methods.chemical-synthesis" }, { "id": "physical.chemistry.methods.chemical-synthesis.polymer-synthesis", "label": "Polymer synthesis", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry.methods.chemical-synthesis.polymer-synthesis" } ], "geo": [ { "id": "geo.nongeo.t2001.physical.chemistry.methods.chemical-synthesis", "label": "Non-geographic · 2001 to 2020: Chemical synthesis", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t2001.physical.chemistry.methods.chemical-synthesis", "path": [ { "id": "geo.nongeo", "label": "Non-geographic", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo" }, { "id": "geo.nongeo.t2001", "label": "Non-geographic · 2001 to 2020", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t2001" }, { "id": "geo.nongeo.t2001.physical", "label": "Physical world and mathematics", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t2001.physical" }, { "id": "geo.nongeo.t2001.physical.chemistry", "label": "Chemistry", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t2001.physical.chemistry" }, { "id": "geo.nongeo.t2001.physical.chemistry.methods", "label": "Chemical principles and methods", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t2001.physical.chemistry.methods" }, { "id": "geo.nongeo.t2001.physical.chemistry.methods.chemical-synthesis", "label": "Chemical synthesis", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t2001.physical.chemistry.methods.chemical-synthesis" } ] } ], "excerpt": "Click polymerization is a family of polymer-forming reactions that joins functional monomers through click reactions, chiefly copper-catalyzed azide–alkyne cycloaddition, delivering well-defined linear, star, and hyperbranched polymers in high yields.", "snippet": "Click polymerization is a family of polymer-forming reactions that joins functional monomers through click reactions, chiefly copper-catalyzed azide–alkyne cycloaddition, delivering well-defined linear, star, and hyperbranched polymers in high yields.", "node": "physical.chemistry.methods.chemical-synthesis.polymer-synthesis", "markdown": "# Click polymerization\n\nClick polymerization is a family of polymer-forming reactions that joins functional monomers through click reactions, most prominently the copper-catalyzed azide–alkyne cycloaddition (CuAAC), to form polymers with high yield and reliability, encompassing both step-growth and chain-growth processes. Because the underlying reactions are modular, selective, and tolerant of many functional groups, the approach delivers well-defined and complex polymeric structures in yields exceeding those typical of conventional step-growth chemistry.[1](https://pubs.rsc.org/en/content/articlelanding/2007/cs/b700809k) Since its introduction, click chemistry's hallmark traits of efficiency, selectivity, and simplicity have been carried into macromolecular synthesis, where azide–alkyne click polymerization is the classic and best-developed alkyne-based family.[2](https://www.tandfonline.com/doi/full/10.1080/10601325.2025.2570388) • [3](https://onlinelibrary.wiley.com/doi/10.1002/agt2.350)\n\n| Key fact | Value |\n|---|---|\n| Principal linkage formed (CuAAC) | 1,4-disubstituted 1,2,3-triazole, exclusively[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC3869285/) |\n| Regioselectivity vs. thermal Huisgen reaction | CuAAC gives only the 1,4-isomer; the uncatalyzed reaction does not[5](https://science-of-synthesis.thieme.com/app/text/?id=SD-235-00101) |\n| Typical CuAAC polymerization conditions | 25–60 °C, 1–10 mol% Cu(I), 1–20 mol% ligand, 2–24 h[6](https://link.springer.com/article/10.1007/s44371-026-00901-4) |\n| Functionalization efficiency | >90% within 4 h at room temperature[6](https://link.springer.com/article/10.1007/s44371-026-00901-4) |\n| Architectures accessible | Linear, star, miktoarm, hyperbranched (degree of branching 0.83), networks[7](https://onlinelibrary.wiley.com/doi/full/10.1002/anie.201502578) • [8](https://pubs.rsc.org/en/content/articlelanding/2015/ra/c5ra02168e) |\n| Metal-free variants | Thiol–yne and amino–yne: >95% conversion, catalyst-free, room temperature[6](https://link.springer.com/article/10.1007/s44371-026-00901-4) |\n| Biomedical constraint | Residual copper above 500 ppm remains a concern[6](https://link.springer.com/article/10.1007/s44371-026-00901-4) |\n\n## How it works\n\nCuAAC is a copper-catalyzed variant of Huisgen's azide–alkyne cycloaddition. With copper(I) salts as catalysts, the triazole forms under mild conditions in a variety of organic solvents at room temperature with quantitative conversion, giving the 1,4-disubstituted 1,2,3-triazole exclusively.[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC3869285/) Unlike the thermally dependent, uncatalyzed [Huisgen reaction](https://www.edgepedia.org/1-3-dipolar-cycloaddition), which produces mixtures of 1,4- and 1,5-regioisomers, CuAAC can exclusively form the 1,4-disubstituted product.[5](https://science-of-synthesis.thieme.com/app/text/?id=SD-235-00101) Mechanistically, CuAAC proceeds through a stepwise pathway involving two copper atoms.[6](https://link.springer.com/article/10.1007/s44371-026-00901-4)\n\nWhen the reaction joins difunctional or multifunctional monomers, it follows step-growth polyaddition kinetics: difunctional monomers form linear chains in consecutive steps, whereas sufficiently multifunctional monomers generate branched structures throughout the matrix until gelation is reached.[9](https://www.mdpi.com/2073-4360/12/5/1084) The triazole product itself can participate in catalysis. In the polymerization of trifunctional AB2 monomers (one alkyne, two azides), the triazole group in a linear unit complexes Cu(I), which catalyzes faster reaction of the second azide group and converts the linear unit into a dendritic unit, producing hyperbranched polymers with a degree of branching of 0.83.[7](https://onlinelibrary.wiley.com/doi/full/10.1002/anie.201502578)\n\n## How it is done\n\nTypical CuAAC polymerizations run at 25–60 °C (higher temperature increases the rate but may cause side reactions) with 1–10 mol% Cu(I) catalyst and 1–20 mol% ligand, at a Cu:ligand ratio of 1:1 to 1:2, in DMF, DMSO, or water, under inert atmosphere for 2–24 h.[6](https://link.springer.com/article/10.1007/s44371-026-00901-4) For hyperbranched products, monomer design uses trifunctional AB2 monomers carrying one alkyne and two azide groups.[7](https://onlinelibrary.wiley.com/doi/full/10.1002/anie.201502578)\n\nFunctional-group tolerance is a defining practical advantage: the reaction conditions are compatible with ester, ether, amide, thioether, Fmoc, and Boc groups, and [Glaser coupling](https://www.edgepedia.org/glaser-coupling) of terminal alkynes can compete under some CuAAC conditions, particularly when oxygen is present, although oxygen exclusion, reducing agents, and stabilizing ligands can suppress it.[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC3869285/) A demonstrated CuAAC functionalization reaches more than 90% efficiency within 4 h at room temperature.[6](https://link.springer.com/article/10.1007/s44371-026-00901-4) Purification must, however, address copper residues, which are difficult to remove completely from the resulting polytriazoles.[3](https://onlinelibrary.wiley.com/doi/10.1002/agt2.350)\n\n## Origin\n\nThe copper(I)-catalyzed alkyne–azide cycloaddition followed earlier efforts to improve the Huisgen azide–alkyne cycloaddition.[10](https://science-of-synthesis.thieme.com/app/text/?id=SD-235-00001) The catalytic effect of copper ions on the azide–alkyne cycloaddition was recognized in independent 2002 reports by Meldal and colleagues and by Rostovtsev, Green, Fokin, and Sharpless; among these, a copper(I)-catalyzed solid-phase synthesis of 1,2,3-triazoles used a terminal alkyne on a hydrophilic tertiary amide-PEG resin and gave triazoles at room temperature with quantitative conversion.[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC3869285/)\n\nFor polymerization specifically, the chain-growth CuAAC polymerization of AB2 monomers for hyperbranched polytriazoles with low polydispersities in a one-pot process was reported by Yi Shi and colleagues in Angewandte Chemie International Edition in 2015.[11](https://doi.org/10.1002/anie.201502578) The unifying concept of x-yne click polymerization, covering thiol-yne, hydroxyl-yne, and amino-yne reactions, was presented by Xinyao Fu, Anjun Qin, and Ben Zhong Tang in Aggregate in 2023.[12](https://doi.org/10.1002/agt2.350)\n\n## Variants\n\nAzide–alkyne click polymerization (AACP) is classified into three categories by catalytic system: Cu(I)-catalyzed, Ru(II)-catalyzed, and metal-free. Cu(I) catalysis gives 1,4-regioregular polytriazoles, while ruthenium-catalyzed systems provide access to the regioisomeric 1,5-disubstituted triazoles.[3](https://onlinelibrary.wiley.com/doi/10.1002/agt2.350) • [2](https://www.tandfonline.com/doi/full/10.1080/10601325.2025.2570388)\n\nThe x-yne family comprises thiol-yne, hydroxyl-yne, and amino-yne click polymerizations, which avoid the use of inherently dangerous azide monomers and are safer to operate than classical AACP.[3](https://onlinelibrary.wiley.com/doi/10.1002/agt2.350) Thiol-yne polymerization has a unique bis-addition feature: the generated vinyl sulfide undergoes further addition with a second thiyl radical, making it suitable for highly crosslinked networks and hyperbranched polymers with high sulfur content. Photo-initiated thiol-yne click polymerization has been used to synthesize highly crosslinked networks and later adapted to 3D printable materials.[3](https://onlinelibrary.wiley.com/doi/10.1002/agt2.350) Metal-free thiol–yne and amino–yne click polymerizations now enable catalyst-free, room-temperature synthesis with more than 95% conversion and up to more than 95% trans selectivity; the same review notes photodegradable polymers from ADMET copolymerization (52 ketones per 1000 methylene units) that degrade with half-lives of 7–20 days under accelerated UV conditions (≥300 W m⁻²), extending the method to sustainable and photodegradable polymers.[6](https://link.springer.com/article/10.1007/s44371-026-00901-4)\n\nA more recent development is controlled/\"living\" click polymerization of monomers containing both azide and alkyne groups within a single molecule, in which polyaddition proceeds through intermolecular click reactions to afford polymers with triazole rings as the main chain; a difunctional initiator can produce linear polymers via possible bidirectional chain-growth propagation.[13](https://pubs.acs.org/jacsat/article/147/25/21459/3737902/Controlled-Living-Click-Polymerization-with) This converts what was a step-growth process into a chain-growth one, enabling precise control over polymer length and structure.[13](https://pubs.acs.org/jacsat/article/147/25/21459/3737902/Controlled-Living-Click-Polymerization-with) • [14](https://www.isct.ac.jp/en/news/67fsvitdbgpc)\n\n## Applications\n\nCuAAC coupling builds star and miktoarm architectures efficiently. Azide-terminated [polybutadiene](https://www.edgepedia.org/polybutadiene) and polystyrene arms were coupled to multialkynyl cores to give 3–12-arm star polymers with coupling yields of at least 85%, and a 4-miktoarm star copolymer of butadiene and styrene was made in one pot with 95.1% yield and PDI 1.04.[8](https://pubs.rsc.org/en/content/articlelanding/2015/ra/c5ra02168e) One-pot AB2 CuAAC polymerization gives polytriazole-based hyperbranched polymers with both low polydispersity and a high degree of branching.[7](https://onlinelibrary.wiley.com/doi/full/10.1002/anie.201502578)\n\nX-yne click polymerization has been applied to polymer networks, hyperbranched polymers, sequence-controlled and sequence-defined polymers, unconventional elastomer materials, fluorescent polymers, surface modification and immobilization, bioconjugation and therapy, and drug release.[3](https://onlinelibrary.wiley.com/doi/10.1002/agt2.350) Light-induced click polymerization of activated alkynes with 2-methylbenzaldehydes yields soluble, thermally stable poly(naphthalene)s, poly(anthracene), and poly(phenanthrene); the resulting poly(anthracene) labels lipid droplets in cells, and TPE-containing polymers show aggregation-induced emission, enabling fluorescent patterns and 2D/3D architectures.[15](https://journal.hep.com.cn/aggregate/EN/10.1002/agt2.70273) Click-type crosslinking is also used for thermosets, where the step-growth mechanism gives homogeneous network formation.[9](https://www.mdpi.com/2073-4360/12/5/1084)\n\n## Limitations and alternatives\n\nThe main limitation of Cu- and Ru-catalyzed azide–alkyne polymerizations is metal contamination: metallic residues in the resulting polytriazoles are difficult to remove completely, which hinders applications in optoelectronic and biological fields.[3](https://onlinelibrary.wiley.com/doi/10.1002/agt2.350) Even with more than 90% functionalization efficiency within 4 h at room temperature, metal residues above 500 ppm Cu remain a concern for biomedical applications.[6](https://link.springer.com/article/10.1007/s44371-026-00901-4) For hydrogels, metal-free click chemistries such as strain-promoted azide–alkyne cycloaddition (SPAAC) serve as alternatives to CuAAC, avoiding residual copper toxicity.[16](https://pmc.ncbi.nlm.nih.gov/articles/PMC11036366/) The x-yne variants additionally avoid azide monomers, which are inherently dangerous.[3](https://onlinelibrary.wiley.com/doi/10.1002/agt2.350)\n\nCompared with conventional step-growth polymerizations, click polymerization is faster and more tolerant: classical step-growth requires more than 99% conversion and precise stoichiometric balance according to Carothers–Flory theory, and typically yields dispersity near 2.[6](https://link.springer.com/article/10.1007/s44371-026-00901-4) Amino–yne click polymerization has activation energies of 35–45 kJ mol⁻¹, lower than CuAAC's 50–70 kJ mol⁻¹, and electron-withdrawing groups increase its reaction rates 10–50 fold.[6](https://link.springer.com/article/10.1007/s44371-026-00901-4) In multifunctional systems, network formation proceeds until gelation, so gelation itself is an expected outcome rather than a failure mode, though it limits processability once reached.[9](https://www.mdpi.com/2073-4360/12/5/1084)\n\n## References\n\n1. [Clicking polymers: a straightforward approach to novel macromolecular architectures (Chem. Soc. Rev., 2007)](https://pubs.rsc.org/en/content/articlelanding/2007/cs/b700809k)\n2. [Copper-catalyzed and metal-free azide-alkyne 'click' reactions: from synthesis and functionalization of small molecules to macromolecules (J. Macromol. Sci. A, 2025)](https://www.tandfonline.com/doi/full/10.1080/10601325.2025.2570388)\n3. [X-yne click polymerization (Fu, 2023, Aggregate)](https://onlinelibrary.wiley.com/doi/10.1002/agt2.350)\n4. [Advancements in the mechanistic understanding of the copper-catalyzed azide–alkyne cycloaddition](https://pmc.ncbi.nlm.nih.gov/articles/PMC3869285/)\n5. [Science of Synthesis: CuAAC section](https://science-of-synthesis.thieme.com/app/text/?id=SD-235-00101)\n6. [Thiol-yne and amino-yne click polymerizations advance step-growth polymerization toward sustainable and photodegradable polymers](https://link.springer.com/article/10.1007/s44371-026-00901-4)\n7. [Chain-Growth Click Polymerization of AB2 Monomers for the Formation of Hyperbranched Polymers with Low Polydispersities in a One-Pot Process (Shi et al., 2015)](https://onlinelibrary.wiley.com/doi/full/10.1002/anie.201502578)\n8. [Highly efficient synthesis and characterization of multiarm and miktoarm star-long-branched polymers via click chemistry (RSC Adv., 2015)](https://pubs.rsc.org/en/content/articlelanding/2015/ra/c5ra02168e)\n9. [The Use of Click-Type Reactions in the Preparation of Thermosets (Polymers, 2020)](https://www.mdpi.com/2073-4360/12/5/1084)\n10. [Science of Synthesis (Thieme)](https://science-of-synthesis.thieme.com/app/text/?id=SD-235-00001)\n11. [Yi Shi and colleagues (2015). Chain‐Growth Click Polymerization of AB2 Monomers for the Formation of Hyperbranched Polymers with Low Polydispersities in a One‐Pot Process. Angewandte Chemie International Edition.](https://doi.org/10.1002/anie.201502578)\n12. [Xinyao Fu, Anjun Qin, Ben Zhong Tang (2023). X‐yne click polymerization. Aggregate.](https://doi.org/10.1002/agt2.350)\n13. [Controlled/\"Living\" Click Polymerization with Possible Bidirectional Chain-Growth Propagation during Polyaddition](https://pubs.acs.org/jacsat/article/147/25/21459/3737902/Controlled-Living-Click-Polymerization-with)\n14. [Turning step-growth into chain-growth with click polymerization (Science Tokyo news)](https://www.isct.ac.jp/en/news/67fsvitdbgpc)\n15. [Spatiotemporally Controlled Light-Induced Click Polymerization of Activated Alkyne With 2-Methylbenzaldehydes for Patterning and Bioimaging Applications](https://journal.hep.com.cn/aggregate/EN/10.1002/agt2.70273)\n16. [Metal-Free Click-Chemistry: A Powerful Tool for Fabricating Hydrogels for Biomedical Applications](https://pmc.ncbi.nlm.nih.gov/articles/PMC11036366/)\n\n---\n*Topic: Encyclopedia › Physical world and mathematics › Chemistry › Chemical principles and methods › Chemical synthesis › Polymer synthesis*\n\n*Initially written Sep 29, 2026 · Edited: Oct 15, 2026; Oct 21, 2026*\n\n*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*\n\nLicense: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license\n", "same_as": [], "url": "https://www.edgepedia.org/click-polymerization", "markdown_url": "https://www.edgepedia.org/click-polymerization.md", "license": { "name": "Edgepedia Community License 1.0", "url": "https://www.edgepedia.org/edgepedia/license", "summary": "Free with credit, commercial use included. AI training is open to everyone. For other uses, organizations over USD 100M in revenue or 100M monthly users license separately.", "spdx": "LicenseRef-Edgepedia-Community-1.0" }, "credit": "\"Click polymerization\", Edgepedia (EdgeChat), https://www.edgepedia.org/click-polymerization. Edgepedia Community License 1.0.", "credit_md": "\"[Click polymerization](https://www.edgepedia.org/click-polymerization)\", Edgepedia (EdgeChat), [https://www.edgepedia.org/click-polymerization](https://www.edgepedia.org/click-polymerization). [Edgepedia Community License 1.0](https://www.edgepedia.org/edgepedia/license).", "credit_html": "\"Click polymerization\", Edgepedia (EdgeChat), https://www.edgepedia.org/click-polymerization. Edgepedia Community License 1.0.", "speakable": "Click polymerization is a family of polymer-forming reactions that joins functional monomers through click reactions, chiefly copper-catalyzed azide–alkyne cycloaddition, delivering well-defined linear, star, and hyperbranched polymers in high yields." }