Construction of CS@APP@UiO-66 through self-assembly technology as flame retardant and smoke suppressant for epoxy resins

Abstract

To achieve fire-resistant epoxy resin (EP), a UiO-66-based novel flame retardant coating (CS@APP@UiO-66) was prepared by modifying UiO-66 with chitosan (CS) and ammonium polyphosphate (APP) through a layer-by-layer (LbL) self-assembly method, which was then introduced into an EP system to improve its fire safety. The results of scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy show that the unsaturated Zr atoms in the UiO-66 framework provide many active sites conducive to modification, so that the UiO-66 particles, which originally had a regular octahedral structure, are more dispersed by LbL modification without causing doping or distortion issues. The thermogravimetric analysis results indicate that the char residue of EP/2% UiO-66 is increased by 2.52% compared with that of pure EP, indicating that the thermal properties of the EP composite are improved after modification. In addition, the cone test results indicate that EP/2%UiO-66-5L has good flame retardancy and smoke suppression properties, and the peak heat release rate, total smoke production and rate of CO generation values are 25.2%, 5.7% and 38.5% lower than those of the unmodified EP. Moreover, it can be concluded from the Raman test that the graphitization degree of the modified EP composite is strengthened. The above results indicated that after the incorporation of CS@APP@UiO-66 into the EP composites, more char layers formed as physical barriers to prevent the transfer of mass and heat, thus reducing the speed of flame propagation. Therefore, the flame resistance and smoke suppression of the EP composites improved. These favorable characteristics, including high flame retardant efficiency and good smoke suppression, make LbL-functionalized UiO-66 promising for flame retardant polymer applications.

Graphical abstract

Keywords

epoxy resin composites / metal organic framework (UiO-66) / layer-by-layer self-assembly (LbL) / flame retardant / smoke suppressant

References

[1] Huo S , Song P , Yu B , Ran S , Chevali V S , Liu L , Fang Z , Wang H . Phosphorus-containing flame retardant epoxy thermosets: recent advances and future perspectives. Progress in Polymer Science, 2021, 114: 101366

[2] Toldy A , Anna P , Csontos I , Szabó A , Marosi G . Intrinsically flame retardant epoxy resin—fire performance and background—Part I. Polymer Degradation & Stability, 2007, 92(12): 2223–2230

[3] Shieh J- Y , Wang C- S . Synthesis of novel flame retardant epoxy hardeners and properties of cured products. Polymer, 2001, 42(18): 7617–7625

[4] Zhi M , Yang X , Fan R , Yue S , Zheng L , Liu Q , He Y . A comprehensive review of reactive flame-retardant epoxy resin: fundamentals, recent developments, and perspectives. Polymer Degradation & Stability, 2022, 201: 109976

[5] Liang B , Cao J , Hong X , Wang C . Synthesis and properties of a novel phosphorous-containing flame-retardant hardener for epoxy resin. Journal of Applied Polymer Science, 2013, 128(5): 2759–2765

[6] Song K , Pan Y- T , Zhang J , Song P , He J , Wang D- Y , Yang R . Metal-organic frameworks- based flame-retardant system for epoxy resin: a review and prospect. Chemical Engineering Journal, 2023, 468: 143653

[7] Wang H , Qiao H , Guo J , Sun J , Li H , Zhang S , Gu X . Preparation of cobalt-based metal organic framework and its application as synergistic flame retardant in thermoplastic polyurethane (TPU). Composites Part B: Engineering, 2020, 182: 107498

[8] Guo W , Nie S , Kalali E N , Wang X , Wang W , Cai W , Song L , Hu Y . Construction of SiO₂@UiO-66 core-shell microarchitectures through covalent linkage as flame retardant and smoke suppressant for epoxy resins. Composites Part B: Engineering, 2019, 176: 107261

[9] Nabipour H , Wang X , Song L , Hu Y . Metal-organic frameworks for flame retardant polymers application: a critical review. Composites Part A: Applied Science and Manufacturing, 2020, 139: 106113

[10] Pan Y T , Zhang Z , Yang R . The rise of MOFs and their derivatives for flame retardant polymeric materials: a critical review. Composites Part B: Engineering, 2020, 199: 108265

[11] Hou Y , Xu Z , Chu F , Gui Z , Song L , Hu Y , Hu W . A review on metal-organic hybrids as flame retardants for enhancing fire safety of polymer composites. Composites Part B: Engineering, 2021, 221: 109014

[12] Shen R , Yan T- H , Ma R , Joseph E , Quan Y , Zhou H- C , Wang Q . Flammability and thermal kinetic analysis of UiO-66-based PMMA polymer composites. Polymers, 2021, 13(23): 4113

[13] Cao M , Xiao G , Chen C , Chen C , Yang Z , Zhong F , Shang S , Wang M , Zou R . Synergetic modification of graphitic carbon nitride by Zr-based metal-organic framework and tetraethoxysilane for improving fire performance in composite coatings. Progress in Organic Coatings, 2023, 183: 107756

[14] Feng W , Zhang J , Yusuf A , Ao X , Shi D , Etacheri V , Wang D- Y . Quasi-solid-state sodium-ion hybrid capacitors enabled by UiO-66@PVDF-HFP multifunctional separators: selective charge transfer and high fire safety. Chemical Engineering Journal, 2022, 427: 130919

[15] Yang Z , Xiao G , Chen C , Chen C , Zhong F , Cao M , Wang M , Zou R , Li R , Shang S . A novel P, N doped organic-inorganic hierarchical core-shell nanostructures: reducing the fire risk of epoxy resin. Progress in Organic Coatings, 2023, 183: 107776

[16] Wu X , Qin Z , Zhang X , Yu Z , Zhang W , Yang R , Li D . Micro-nanometer particle composition and functional design of surface nano-structured ammonium polyphosphate and its application in intumescent flame-retardant polypropylene. Nanomaterials, 2022, 12(4): 606

[17] Unnikrishnan V , Zabihi O , Li Q , Ahmadi M , Yadav R , Kalali E N , Tanwar K , Kiziltas A , Blanchard P , Wang D- Y . . Organophosphorus-functionalized zirconium-based metal-organic framework nanostructures for improved mechanical and flame retardant polymer nanocomposites. ACS Applied Nano Materials, 2021, 4(12): 13027–13040

[18] Deng C- L , Du S- L , Zhao J , Shen Z- Q , Deng C , Wang Y- Z . An intumescent flame retardant polypropylene system with simultaneously improved flame retardancy and water resistance. Polymer Degradation & Stability, 2014, 108: 97–107

[19] Du B , Ma H , Fang Z . How nano-fillers affect thermal stability and flame retardancy of intumescent flame retarded polypropylene. Polymers for Advanced Technologies, 2011, 22(7): 1139–1146

[20] Zhang J , Ao X , Zhang X , Wang R , Jin X , Ye W , Xu B , Wang D- Y . Construction of nanomaterials based on molybdenum disulfide decorated onto a metal-organic framework (UiO-66) to improve the fire retardancy of epoxy. ACS Applied Nano Materials, 2022, 5(12): 17731–17740

[21] Ou M , Cui J , Zhao Z , Li R , Guan H , Liu L , Jiao C , Chen X . Solvent-free intumescent fire protection epoxy coatings with excellent smoke suppression, toxicity reduction, and durability enabled by a micro/nano-structured P/N/Si-containing flame retardant. Progress in Organic Coatings, 2023, 183: 107762

[22] Sun Q , Wang J , Meng X , Zhang J , Yan H . A novel high-efficient P/N/Si-containing APP-based flame retardant with a silane coupling agent in its molecular structure for epoxy resin. Chinese Journal of Chemical Engineering, 2023, 55: 137–147

[23] Shen R , Quan Y , Zhang Z , Ma R , Wang Q . Metal-organic framework as an efficient synergist for intumescent flame retardants against highly flammable polypropylene. Industrial & Engineering Chemistry Research, 2022, 61(21): 7292–7302

[24] Jin X , Wu X , Liu Q , Sun S , Cui S , Zhang S , Chen C . Preparation of a novel Fe-MOF as the flame retardant synergist and its application in polystyrene. Polymers for Advanced Technologies, 2024, 35(1): e6221

[25] De Villiers M M , Otto D P , Strydom S J , Lvov Y M . Introduction to nanocoatings produced by layer-by-layer (LbL) self-assembly. Advanced Drug Delivery Reviews, 2011, 63(9): 701–715

[26] Weng G- M , Li J , Alhabeb M , Karpovich C , Wang H , Lipton J , Maleski K , Kong J , Shaulsky E , Elimelech M . . Layer-by-layer assembly of cross-functional semi-transparent MXene-carbon nanotubes composite films for next-generation electromagnetic interference shielding. Advanced Functional Materials, 2018, 28(44): 1803360

[27] Li K , Zou G , Jiao T , Xing R , Zhang L , Zhou J , Zhang Q , Peng Q . Self-assembled MXene-based nanocomposites via layer-by-layer strategy for elevated adsorption capacities. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2018, 553: 105–113

[28] Kotov N A . Layered biomimetic composites from MXenes with sequential bridging. Angewandte Chemie International Edition, 2022, 61(13): e202114140

[29] Wu Y , Long Y , Li Q- L , Han S , Ma J , Yang Y- W , Gao H . Layer-by-layer (LBL) self-assembled biohybrid nanomaterials for efficient antibacterial applications. ACS Applied Materials & Interfaces, 2015, 7(31): 17255–17263

[30] Bansal K , Mansouri S , Bajwa D , Swarup S , Quadir M . Synthesis of phytic acid-layered zinc oxide hybrid nanoparticles and their flame-retardant applications in polyurethane coatings. Journal of Coatings Technology and Research, 2024, 21(1): 369–382

[31] Cavka J H , Jakobsen S , Olsbye U , Guillou N , Lamberti C , Bordiga S , Lillerud K P . A new zirconium inorganic building brick forming metal organic frameworks with exceptional stability. Journal of the American Chemical Society, 2008, 130(42): 13850–13851

[32] Katz M J , Brown Z J , Colón Y J , Siu P W , Scheidt K A , Snurr R Q , Hupp J T , Farha O K . A facile synthesis of UiO-66, UiO-67 and their derivatives. Chemical Communications, 2013, 49(82): 9449–9451

[33] Zou D , Liu D . Understanding the modifications and applications of highly stable porous frameworks via UiO-66. Materials Today Chemistry, 2019, 12: 139–165

[34] Tan Y , Zhang W , Gao Y , Wu J , Tang B . Facile synthesis and supercapacitive properties of Zr-metal organic frameworks (UiO-66). RSC Advances, 2015, 5(23): 17601–17605

[35] Semrau A L , Fischer R A . High-quality thin films of UiO-66-NH₂ by coordination modulated layer-by-layer liquid phase epitaxy. Chemistry, 2021, 27(33): 8509–8516

[36] Chen C , Chen D , Xie S , Quan H , Luo X , Guo L . Adsorption behaviors of organic micropollutants on zirconium metal-organic framework UiO-66: analysis of surface interactions. ACS Applied Materials & Interfaces, 2017, 9(46): 41043–41054

[37] Guo W , Liu J , Zhang P , Song L , Wang X , Hu Y . Multi-functional hydroxyapatite/polyvinyl alcohol composite aerogels with self-cleaning, superior fire resistance and low thermal conductivity. Composites Science and Technology, 2018, 158: 128–136

[38] Li J , Gong J- L , Zeng G- M , Zhang P , Song B , Cao W- C , Liu H- Y , Huan S- Y . Zirconium-based metal organic frameworks loaded on polyurethane foam membrane for simultaneous removal of dyes with different charges. Journal of Colloid and Interface Science, 2018, 527: 267–279

[39] Ragon F , Campo B , Yang Q , Martineau C , Wiersum A D , Lago A , Guillerm V , Hemsley C , Eubank J F , Vishnuvarthan M . . Acid-functionalized UiO-66(Zr) MOFs and their evolution after intra-framework cross-linking: structural features and sorption properties. Journal of Materials Chemistry A: Materials for Energy and Sustainability, 2015, 3(7): 3294–3309

[40] Valenzano L , Civalleri B , Chavan S , Bordiga S , Nilsen M H , Jakobsen S , Lillerud K P , Lamberti C . Disclosing the complex structure of UiO-66 metal organic framework: a synergic combination of experiment and theory. Chemistry of Materials, 2011, 23(7): 1700–1718

[41] Guo W , Zhao Y , Wang X , Cai W , Wang J , Song L , Hu Y . Multifunctional epoxy composites with highly flame retardant and effective electromagnetic interference shielding performances. Composites Part B: Engineering, 2020, 192: 107990

[42] Guo W , Wang X , Huang J , Zhou Y , Cai W , Wang J , Song L , Hu Y . Construction of durable flame-retardant and robust superhydrophobic coatings on cotton fabrics for water-oil separation application. Chemical Engineering Journal, 2020, 398: 125661

[43] Guo W , Wang X , Zhang P , Liu J , Song L , Hu Y . Nano-fibrillated cellulose-hydroxyapatite based composite foams with excellent fire resistance. Carbohydrate Polymers, 2018, 195: 71–78

[44] Huang Z , Li S , Tsai L- C , Jiang T , Ma N , Tsai F- C . Flame retardant polypropylene with a single molecule intumescent flame retardant based on chitosan. Materials Today Communications, 2022, 33: 104689

[45] Liu L , Yao M , Zhang H , Zhang Y , Feng J , Fang Z , Song P . Aqueous self-assembly of bio-based flame retardants for fire-retardant, smoke-suppressive, and toughened polylactic acid. ACS Sustainable Chemistry & Engineering, 2022, 10(49): 16313–16323

[46] Wang X , Qi P , Zhang S , Jiang S , Li Y , Sun J , Fei B , Gu X , Zhang S . A novel flame-retardant modification strategy for UiO66-NH₂ by encapsulating triethyl phosphate: preparation, characterization, and multifunctional application in poly(lactic acid). Materials Today Chemistry, 2023, 30: 101550

[47] Sai T , Ran S , Guo Z , Fang Z . A Zr-based metal organic frameworks towards improving fire safety and thermal stability of polycarbonate. Composites Part B: Engineering, 2019, 176: 107198

[48] Huang J , Guo W , Wang X , Niu H , Song L , Hu Y . Combination of cardanol-derived flame retardant with SiO₂@MOF particles for simultaneously enhancing the toughness, anti-flammability and smoke suppression of epoxy thermosets. Composites Communications, 2021, 27: 100904

[49] Zhang X , Zhang W , Zeng G , Du J , Zhang W , Yang R . The effect of different smoke suppressants with APP for enhancing the flame retardancy and smoke suppression on vinyl ester resin. Polymer Engineering and Science, 2020, 60(2): 314–322

[50] Jiao C , Wang H , Zhang Z , Chen X . Preparation and properties of an efficient smoke suppressant and flame-retardant agent for thermoplastic polyurethane. Polymers for Advanced Technologies, 2017, 28(12): 1690–1698

[51] Wu K , Zhou C , Pan Z , Cheng Q , Feng L , Wu H , Zhou H . Flame-retardant epoxy resin with good smoke-suppression endowed by chitosan-cobalt/phosphorus complex. Journal of Applied Polymer Science, 2024, 141(6): e54919

[52] Duan R , Wu H , Li J , Zhou Z , Meng W , Liu L , Qu H , Xu J . Phosphor nitrile functionalized UiO-66-NH₂/graphene hybrid flame retardants for fire safety of epoxy. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2022, 635: 128093

[53] WangRZhangXYuanMWangD- YZhangJPanY- T. Fire retardancy of epoxy composites: a comparative investigation on the influence of porous structure and transition metal of metal-organic framework. Composites Communications, 2024

[54] Zhang J , Li Z , Shao Z- B , Zhang L , Wang D- Y . Hierarchically tailored hybrids via interfacial-engineering of self-assembled UiO-66 and Prussian Blue analogue: novel strategy to impart epoxy high-efficient fire retardancy and smoke suppression. Chemical Engineering Journal, 2020, 400: 125942

[55] Chen C , Song W , Jiang M , Zhang R , Li S , Cai Y , Yao J . SiO₂/MOFs-based synergistic flame retardants provide enhanced fire safety for epoxy resins. Materials Today Communications, 2023, 35: 105805

[56] Zhang G , Dong Y , Yao M , Cui Y , Meng W , Wang S , Qu H , Xu J . Preparation of a MOF flame retardant containing phosphazene ring and its effect on the flame retardant of epoxy resin. Reactive & Functional Polymers, 2023, 191: 105670

[57] Zhang A , Zhang J , Liu L , Dai J , Lu X , Huo S , Hong M , Liu X , Lynch M , Zeng X . . Engineering phosphorus-containing lignin for epoxy biocomposites with enhanced thermal stability, fire retardancy and mechanical properties. Journal of Materials Science and Technology, 2023, 167: 82–93

[58] ChenQLiuLZhangAWangWWangZZhangJFengJHuoSZengXSongP. An iron phenylphosphinate@graphene oxide nanohybrid enabled flame-retardant, mechanically reinforced, and thermally conductive epoxy nanocomposites. Chemical Engineering Journal, 2022

[59] Velencoso M M , Battig A , Markwart J C , Schartel B , Wurm F R . Molecular firefighting— how modern phosphorus chemistry can help solve the flame retardancy task. Angewandte Chemie International Edition, 2018, 57(33): 10450–10467

[60] Guo W , Wang X , Gangireddy C S R , Wang J , Pan Y , Xing W , Song L , Hu Y . Cardanol derived benzoxazine in combination with boron-doped graphene toward simultaneously improved toughening and flame retardant epoxy composites. Composites Part A: Applied Science and Manufacturing, 2019, 116: 13–23

[61] Zhang J , Li Z , Qi X , Zhang W , Wang D- Y . Size tailored bimetallic metal-organic framework (MOF) on graphene oxide with sandwich-like structure as functional nano-hybrids for improving fire safety of epoxy. Composites Part B: Engineering, 2020, 188: 107881

RIGHTS & PERMISSIONS

Higher Education Press