{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,8]],"date-time":"2026-01-08T05:58:28Z","timestamp":1767851908622,"version":"3.49.0"},"reference-count":34,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2024,4,19]],"date-time":"2024-04-19T00:00:00Z","timestamp":1713484800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Innovation Fund of Engineering Research Center of Phosphorus Resources Development and Utilization of Ministry of Education","award":["LCX202307"],"award-info":[{"award-number":["LCX202307"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Halogen-free organophosphorus flame retardants have promising application prospects due to their excellent safety and environmental protection properties. A cobalt-coordinated cyclic phosphonitrile flame retardant (Co@CPA) was synthesized via a hydrothermal method using hexachlorocyclotriphosphonitrile (HCCP), 5-amino-tetrazolium (5-AT), and cobalt nitrate hexahydrate (Co(NO3)2\u22196H2O) as starting materials. The structure was characterized using Fourier transform infrared (FTIR), nuclear magnetic resonance spectroscopy (1H-NMR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Thermoplastic polyurethane (TPU) composites were prepared by incorporating 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphame-10-oxide (ODOPB), Co@CPA, and silicon dioxide (SiO2) via melt blending. The flame-retardant performance and thermal stability of the TPU composites were evaluated through limiting oxygen index (LOI), vertical combustion (UL-94), TG, and cone calorimetric (CCT) tests. SEM and Raman spectroscopy were used to analyze the surface morphology and structure of the residual carbon. A synergistic flame-retardant effect of ODOPB and Co@CPA was observed, with the most effective flame retardancy achieved at a TPU:ODOPB:Co@CPA:SiO2 ratio of 75:16:8:1. This composition exhibited an LOI value of 26.5% and achieved a V-0 rating in the UL-94 test. Furthermore, compared to pure TPU, the composite showed reductions in total heat release, CO production, and CO2 production by 6.6%, 39.4%, and 48.9%, respectively. Our research findings suggest that Co@CPA demonstrates outstanding performance, with potential for further expansion in application areas. Different metal-based cyclic phosphonitrile compounds are significant in enriching phosphorus-based fine chemicals.<\/jats:p>","DOI":"10.3390\/molecules29081869","type":"journal-article","created":{"date-parts":[[2024,4,19]],"date-time":"2024-04-19T08:44:31Z","timestamp":1713516271000},"page":"1869","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Characterization and Flame-Retardant Properties of Cobalt-Coordinated Cyclic Phosphonitrile in Thermoplastic Polyurethane Composites"],"prefix":"10.3390","volume":"29","author":[{"given":"Xiangcong","family":"Zeng","sequence":"first","affiliation":[{"name":"School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zhi","family":"Xu","sequence":"additional","affiliation":[{"name":"School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Haoxun","family":"Li","sequence":"additional","affiliation":[{"name":"School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yun","family":"Xiong","sequence":"additional","affiliation":[{"name":"School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yigang","family":"Ding","sequence":"additional","affiliation":[{"name":"School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lili","family":"Xu","sequence":"additional","affiliation":[{"name":"School of Technology Materials Science and Engineering, Wuhan Institute of Technology, Wuhan 430205, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Shengpeng","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2024,4,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"141448","DOI":"10.1016\/j.cej.2023.141448","article-title":"Design of Novel Double-Layer Coated Ammonium Polyphosphate and its Application in Flame Retardant Thermoplastic Polyurethanes","volume":"459","author":"Wan","year":"2023","journal-title":"Chem. Eng. J."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"4450","DOI":"10.1002\/pat.5448","article-title":"Synergistic Function of N-P-Cu Containing Supermolecular Assembly Networks in Intumescent Flame Retardant Thermoplastic Polyurethane","volume":"32","author":"Chen","year":"2021","journal-title":"Polym. Adv. Technol."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Khudaida, S.H., Yen, S.-K., and Su, C.-S. (2024). The Application of Box-Behnken Design for Investigating the Supercritical CO2 Foaming Process: A Case Study of Thermoplastic Polyurethane 85a. Molecules, 29.","DOI":"10.3390\/molecules29020363"},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Wang, Z., Jiang, Y., Yang, X., Zhao, J., Fu, W., Wang, N., and Wang, D. (2022). Surface Modification of Ammonium Polyphosphate for Enhancing Flame-Retardant Properties of Thermoplastic Polyurethane. Materials, 15.","DOI":"10.3390\/ma15061990"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2061","DOI":"10.1002\/pat.6041","article-title":"Thermoplastic Polyurethane for Three-Dimensional Printing Applications: A Review","volume":"34","author":"Desai","year":"2023","journal-title":"Polym. Adv. Technol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"2714","DOI":"10.1021\/acs.biomac.0c00456","article-title":"Zwitterion Surface-Functionalized Thermoplastic Polyurethane for Antifouling Catheter Applications","volume":"21","author":"Nikam","year":"2020","journal-title":"Biomacromolecules"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"392","DOI":"10.1007\/s10965-023-03778-4","article-title":"Fire Behavior and Mechanical Properties of Phosphorus-Containing Silica Gel Coated Ammonium Polyphosphate as Fire Retardants in Thermoplastic Polyurethane (Tpu)","volume":"30","author":"Zheng","year":"2023","journal-title":"J. Polym. Res."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"G\u0142owi\u0144ska, E., Gotkiewicz, O., and Kosmela, P. (2023). Sustainable Strategy for Algae Biomass Waste Management Via Development of Novel Bio-Based Thermoplastic Polyurethane Elastomers Composites. Molecules, 28.","DOI":"10.3390\/molecules28010436"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Tong, Y., Wu, W., Zhao, W., Xing, Y., Zhang, H., Wang, C., Chen, T.B.Y., Yuen, A.C.Y., Yu, B., and Cao, X. (2022). Nanohybrid of Co3O4 Nanoparticles and Polyphosphazene-Decorated Ultra-Thin Boron Nitride Nanosheets for Simultaneous Enhancement in Fire Safety and Smoke Suppression of Thermoplastic Polyurethane. Polymers, 14.","DOI":"10.3390\/polym14204341"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Lu, S., Shen, B., and Chen, X. (2021). Construction of Charring-Functional Polyheptanazine Towards Improvements in Flame Retardants of Polyurethane. Molecules, 26.","DOI":"10.3390\/molecules26020340"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1041","DOI":"10.1002\/pen.26264","article-title":"Inorganic\/Organic Phosphorus-Based Flame Retardants Synergistic Flame Retardant Rigid Polyurethane Foam","volume":"63","author":"Wu","year":"2023","journal-title":"Polym. Eng. Sci."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1003","DOI":"10.1002\/fam.3145","article-title":"The Impact of Halogen Free Phosphorus, Inorganic and Nitrogen Flame Retardants on the Toxicity and Density of Smoke From 10 Common Polymers","volume":"47","author":"Feuchter","year":"2023","journal-title":"Fire Mater."},{"key":"ref_13","unstructured":"Silva, N.G., Zanini, N.C., de Souza, A.G., Barbosa, R.F., Rosa, D.S., and Mulinari, D.R. (2021). Materials and Chemistry of Flame-Retardant Polyurethanes Volume 1: A Fundamental Approach, ACS Publications."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Zem\u0142a, M., Prociak, A., and Micha\u0142owski, S. (2021). Bio-Based Rigid Polyurethane Foams Modified with Phosphorus Flame Retardants. Polymers, 14.","DOI":"10.3390\/polym14010102"},{"key":"ref_15","unstructured":"Olcay, H., Gul, C., and Kocak, E.D. (2021). Materials and Chemistry of Flame-Retardant Polyurethanes Volume 2: Green Flame Retardants, ACS Publications."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"23322","DOI":"10.1039\/D2RA02586H","article-title":"Halogen-Free Layered Double Hydroxide-Cyclotriphosphazene Carboxylate Flame Retardants: Effects of Cyclotriphosphazene Di, Tetra and Hexacarboxylate Intercalation on Layered Double Hydroxides Against the Combustible Epoxy Resin Coated on Wood Substrates","volume":"12","author":"Jeevananthan","year":"2022","journal-title":"RSC Adv."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Mayer-Gall, T., Plohl, D., Derksen, L., Lauer, D., Neldner, P., Ali, W., Fuchs, S., Gutmann, J.S., and Opwis, K. (2019). A Green Water-Soluble Cyclophosphazene as a Flame Retardant Finish for Textiles. Molecules, 24.","DOI":"10.3390\/molecules24173100"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"3263","DOI":"10.1002\/pat.5778","article-title":"Cyclotriphosphazene Hyperbranched P\/N\/Si Prepared Flame Retardants Improve Mechanical Properties and Flame Retardancy of Epoxy Resins","volume":"33","author":"Yu","year":"2022","journal-title":"Polym. Adv. Technol."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Zhu, Y., Wu, W., Xu, T., Xu, H., Zhong, Y., Zhang, L., Ma, Y., Sui, X., Wang, B., and Feng, X. (2022). Morphology-Controlled Synthesis of Polyphosphazene-Based Micro-and Nano-Materials and their Application as Flame Retardants. Polymers, 14.","DOI":"10.3390\/polym14102072"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"109651","DOI":"10.1016\/j.polymdegradstab.2021.109651","article-title":"A Novel Aminothiazole-Based Cyclotriphosphazene Derivate Towards Epoxy Resins for High Flame Retardancy and Smoke Suppression","volume":"190","author":"Ning","year":"2021","journal-title":"Polym. Degrad. Stabil."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"140678","DOI":"10.1016\/j.cej.2022.140678","article-title":"Unveiling the Structure, Chemistry, and Formation Mechanism of an in-Situ Phosphazene Flame Retardant-Derived Interphase Layer in Lifepo4 Cathode","volume":"455","author":"Yusuf","year":"2023","journal-title":"Chem. Eng. J."},{"key":"ref_22","unstructured":"Ca\u0434\u0438\u043ao\u0432, P.M., Hyp\u043ay\u043bo\u0432, \u042d.H., and \u0414\u0436a\u043b\u0438\u043bo\u0432, A.T. (2022). Preparation of Fire-Retardant Polymeric Materials Based on Phosphorus and Metal-Containing Flame Retardants and Study of Physical and Mechanical Properties. Zenodo (CERN Eur. Organ. Nucl. Res.)."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"101482","DOI":"10.1016\/j.mtchem.2023.101482","article-title":"Construction of Bimetallic Metal-Organic Frameworks\/Graphitic Carbon Nitride Hybrids as Flame Retardant for Unsaturated Polyester Resin","volume":"30","author":"Yang","year":"2023","journal-title":"Mater. Today Chem."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Lyu, P., Hou, Y., Hu, J., Liu, Y., Zhao, L., Feng, C., Ma, Y., Wang, Q., Zhang, R., and Huang, W. (2022). Composites Filled with Metal Organic Frameworks and their Derivatives: Recent Developments in Flame Retardants. Polymers, 14.","DOI":"10.3390\/polym14235279"},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Xu, B., Wu, M., Liu, Y., and Wei, S. (2023). Study on Flame Retardancy Behavior of Epoxy Resin with Phosphaphenanthrene Triazine Compound and Organic Zinc Complexes Based On Phosphonitrile. Molecules, 28.","DOI":"10.3390\/molecules28073069"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"49326","DOI":"10.1021\/acsami.2c14740","article-title":"Multielement Flame-Retardant System Constructed with Metal Poss-Organic Frameworks for Epoxy Resin","volume":"14","author":"Hou","year":"2022","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"489","DOI":"10.1016\/j.jcis.2023.04.047","article-title":"Metal-Organic Framework-Derived Bird\u2019s Nest-Like Capsules for Phosphorous Small Molecules Towards Flame Retardant Polyurea Composites","volume":"643","author":"Song","year":"2023","journal-title":"J. Colloid. Interface Sci."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Lv, J., Li, Z., Dong, R., Xue, Y., Wang, Y., and Li, Q. (2023). Highly Flame-Retardant Materials of Different Divalent Metal Ions Alginate\/Silver Phosphate: Synthesis, Characterizations, and Synergistic Phosphorus-Polymetallic Effects. Int. J. Biol. Macromol., 247.","DOI":"10.1016\/j.ijbiomac.2023.125834"},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Chai, H., Li, W., Wan, S., Liu, Z., Zhang, Y., Zhang, Y., Zhang, J., and Kong, Q. (2023). Amino Phenyl Copper Phosphate-Bridged Reactive Phosphaphenanthrene to Intensify Fire Safety of Epoxy Resins. Molecules, 28.","DOI":"10.3390\/molecules28020623"},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Song, K., Bi, X., Yu, C., Pan, Y.-T., Xiao, P., Wang, J., Song, J.-I., He, J., and Yang, R. (2024). Structure of Metal-Organic Frameworks Eco-Modulated by Acid-Base Balance Toward Biobased Flame Retardant in Polyurea Composites. ACS Appl. Mater. Interfaces.","DOI":"10.1021\/acsami.4c02187"},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Ma, T., Wang, W., and Wang, R. (2023). Thermal Degradation and Carbonization Mechanism of Fe-Based Metal-Organic Frameworks Onto Flame-Retardant Polyethylene Terephthalate. Polymers, 15.","DOI":"10.3390\/polym15010224"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"234","DOI":"10.1016\/j.jcis.2022.01.101","article-title":"Synthesis of Sugar Gourd-Like Metal Organic Framework-Derived Hollow Nanocages Nickel Molybdate@Cobalt-Nickel Layered Double Hydroxide for Flame Retardant Polyurea","volume":"616","author":"Wang","year":"2022","journal-title":"J. Colloid. Interface Sci."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Huang, R., Guo, X., Ma, S., Xie, J., Xu, J., and Ma, J. (2020). Novel Phosphorus-Nitrogen-Containing Ionic Liquid Modified Metal-Organic Framework as an Effective Flame Retardant for Epoxy Resin. Polymers, 12.","DOI":"10.3390\/polym12010108"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"2829","DOI":"10.1002\/pat.5260","article-title":"Copper metal-organic framework toward flame-retardant enhancement of thermoplastic polyurethane elastomer composites based on ammonium polyphosphate","volume":"32","author":"Chen","year":"2021","journal-title":"Polym. Adv. Technol."}],"container-title":["Molecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1420-3049\/29\/8\/1869\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T14:31:05Z","timestamp":1760106665000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1420-3049\/29\/8\/1869"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,4,19]]},"references-count":34,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2024,4]]}},"alternative-id":["molecules29081869"],"URL":"https:\/\/doi.org\/10.3390\/molecules29081869","relation":{},"ISSN":["1420-3049"],"issn-type":[{"value":"1420-3049","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,4,19]]}}}