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Zirconium phenyl phosphate (ZrPP) has good compatibility in polymers due to its simultaneous inorganic-organic structure. Here, ZrPP was anchored on high barrier boron nitride (BN) by an in situ synthesis scheme using polyaniline (PANI) as an intermediate, which is expected to yield a high performance multifunctional composite flame retardant. Among them, the formation of a rational composite structure of ZrPP and BN is conducive to the maximum enhancement of its barrier effect. Moreover, the presence of Zr and phosphoric acid molecules can effectively promote the cyclization of cleaved molecules and carbon formation in the burning stage, which reinforced the quality and strength of residual carbon. The results showed that the back side temperature of BP@ZrPP/EP waterborne coating was stabilized at the lowest value (167.2 °C), accounting for the most excellent thermal insulation effect of its residual carbon. The BP@ZrPP/EP composite coating showed the maximum expansion height (23.8 mm), expansion rate (18.03) and residual carbon (31.8 %), which depends on the synergistic barrier function of ZrPP and BN. Further, BP@ZrPP based EP exhibited the smallest smoke density rating (38.2 %), the largest limiting oxygen index (31.4 %), and achieved a V 0 rating for the UL-94 test. Compared with EP, the peak heat release rate (PHRR), total heat release rate (THR), peak smoke production rate (PSPR), total smoke production (TSP), and peak CO production rate (PCOPR) of BP@ZrPP-filled EP were reduced by 32.9 %, 30.7 %, 33.3 %, 31.3 %, and 35.4 %, respectively, proving its excellent flame retardant and smoke inhibition ability. [Display omitted] • PANI with flame retardancy was deposited on the surface of BN to improve its dispersion state. • ZrPP were uniformly loaded on BN surface to obtain high barrier nano-flame retardant. • Zr ions in ZrPP played a catalytic role in the formation of residual carbon. • Phosphate ions in ZrPP promote the conversion of more pyrolysis products to carbon. [ABSTRACT FROM AUTHOR]

Polyaniline (PANI), a polymer with a high nitrogen content, has been shown to have good flame retardant properties. Here, we significantly improved the self-carbon formation ability of PANI at high temperature by doping with phytic acid (PA). Meanwhile, a new organic-metal ion flame retardant (DPANI/PA@Cu) was obtained by introducing Cu2+ with catalytic carbon formation property into PANI/PA using the complexation between transition metal ions and PA. Surprisingly, the introduction of metal ions was also able to trigger the formation of dendritic structure of PANI (DPANI), which is important for its dispersion in resin matrix and strengthening effect on the coating. The test results demonstrated that the composite coating with 5% content of DPANI/PA@Cu had the lowest back-side temperature (174.9 ℃), the highest expansion height (18.5 mm) and the lowest smoke density class (45.3%). In addition, the DPANI/PA@Cu 5% /EP composite coating retained the maximum amount of residual carbon (29.7%), which was mainly related to the synergistic catalytic effect of PA and Cu2+. Ultimately, the retained PANI residual carbon and CuO nanoparticles diffused in the char layer acted as interceptors for the external flame and heat. [Display omitted] • The C-N-P fire protection system was constructed by adding PA to the synthesis of PANI. • Dendritic polyaniline (DPANI) was obtained by the introduction of metallic copper ions. • The doped copper ions promoted the conversion of more cracked material to char. • Self-forming carbon PANI and residual CuO improve the adiabatic effect of the residual carbon. [ABSTRACT FROM AUTHOR]

It is obvious that boron nitride (BN) can provide excellent barrier to heat and flame due to its large lamellar structure and high thermal stability. Here, we combined the barrier effect of BN with the catalytic effect of transition metal ions to obtain a novel nanocomposite coating. Specifically, polyethyleneimine (PEI) molecules were loaded on the BN surface by Lewis acid-base action. Then, the phytic acid (PA) molecules were self-assembled on the PEI surface by electrostatic action. Finally, copper ions (Cu2+) were complexed in the PA molecules to obtain BN/PPA@Cu hybrids. The fire performance and smoke suppression effects of BN/PPA@Cu loaded epoxy resin (EP) composite coatings were discussed and analyzed by large plate experiments, thermal weight loss analysis, etc. In comparison, the backside temperature of the steel plate with BN/PPA@Cu/EP composite coating was stabilized at 167.8 °C, which was significantly lower than other samples, while its lowest smoke density rating (39.9) confirmed its excellent smoke suppression effect. The results of thermal weight loss analysis proved that BN/PPA@Cu/EP had the lowest T max (334.8 °C), which was a direct response to the catalytic effect of transition metal ions. Additionally, the highest char residue (31.1%) and the maximum expansion height (21.9 mm) of BN/PPA@Cu/EP conferred high fire resistance and smoke suppression to the composite coating. These findings are a good reference for obtaining high performance fireproof coatings. [Display omitted] • PA, Cu2+ were loaded on BN/PEI surface sequentially by electrostatic interaction and complexation. • The synergistic effect of PEI, PA and Cu2+ effectively improved the fire performance of the coating. • Residual CuO and BN improved the strength and thermal insulation of the char layer. [ABSTRACT FROM AUTHOR]

Herein, polyethyleneimine (PEI) was loaded on the surface of BN nanosheets to impart them a positive charge. Then, negatively charged zinc hydroxystannate (ZHS) nanoparticles were adsorbed on the surface of BN/PEI composites through electrostatic self-assembly to obtain a novel BN/PEI@ZHS nanoadditive (BP@ZHS). The contribution of BP@ZHS hybrids to the flame retardant properties of epoxy coatings (EP) was characterized by fire performance tests. The thermal insulation performance test results showed that the backside temperature of the BP@ZHS based epoxy (BP@ZHS/EP) fireproof coating remained the lowest value (172.1 ℃) after 60 min of burning. The BP@ZHS/EP sample exhibited the most excellent expansion characteristics (expansion height is 21.5 mm, expansion rate is 16.54) after calcination in a muffle furnace. The TGA experiments illustrated that BP@ZHS/EP had the largest amount (30.8%) of carbon residue due to its catalytic carbonization. Moreover, the smoke density rating (SDR, 46.8%) of BP@ZHS/EP was significantly lower than other samples due to the synergistic effect of BN and ZHS. The carbon residue analysis showed that zinc stannate and BN remained in the carbon framework, thereby improving the strength and thermal insulation effect of the char layer. The excellent fire resistance of BP@ZHS/EP can be mainly attributed to the high barrier effect of BN nanosheets and the multifunctional flame retardant effect of ZHS. [Display omitted] • PEI molecular was coated on the BN surface to give its surface a positive charge. • The ZHS nanoparticles were anchored on the surface of BN/PEI on the basis of electrostatic interaction. • The water released by ZHS at high temperature delayed the combustion reaction • Residual zinc stannate and BN promoted the formation of carbon residues and improved the thermal insulation of the char layer. [ABSTRACT FROM AUTHOR]

Multi-walled carbon nanotubes (MWCNTs) were acidified with nitration mixture, and the Fe2O3-MWCNTs (iron oxide coated multi-walled carbon nanotubes) hybrid material via sol-gel method then verified the results through scanning electron microscope, X-ray diffraction, and thermal gravimetric analysis. We modified the hybrid material with silane coupling agent (KH560), Fe2O3-MWCNTs/epoxy, MWCNTs/epoxy composites coating, and the pure epoxy coatings were respectively prepared. The properties of the composite coatings were tested through the electrochemical workstation (electrochemical impedance spectroscopy), shock experiments, and thermal gravimetric analysis. Finally, we used scanning electron microscope to observe the surface conditions of the coatings. The results show that Fe2O3-MWCNTs have good dispersion in the epoxy resin, and the Fe2O3-MWCNTs/epoxy composite coatings have enhanced mechanical properties and corrosion resistance. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Utilization of self-healing coating is an efficient strategy for protecting metals from corrosion. However, rational design and synthesis of self-healing nanomaterial with excellent barrier property and high loading rate of corrosion inhibitor is still a challenge. Herein, the obvious physical barrier properties of graphene and the self-healing function of zeolite imidazole framework-8 (ZIF-8) was combined (RGO@ZIF) based on the concept of composite coating with "passive barrier" body and "active self-healing" guest. Herein, as a coordination complex, ZIF-8 can store and release inhibitors (2-methylimidazole) through the formation and cleavage of coordination bonds. Moreover, silica was supported on the ZIF surface (RGO@ZIF@SiO 2) to compensate for the negative impact of the remaining voids after ZIF decomposition on the barrier properties of the coatings. The UV–vis results proved that ZIF-8 displayed outstanding pH-responsive activities under acidic conditions, and the loading capacity was up to 63.0%. Therefore, ZIF-8 was proposed as a solid corrosion inhibitor, which is expected to provide a new way to improve the loading rate of inhibitors. The EIS results showed that the impedance values of ZIF/EP, RGO@ZIF/EP and RGO@ZIF@SiO 2 /EP composites coatings increased inversely with the prolongation of immersion time, attributing to their self-healing performance. Besides, the epoxy loaded 0.7% of RGO@ZIF@SiO 2 exhibited the higher impedance value than that of other samples in the whole immersion stage, which can be ascribed to the excellent barrier properties. Moreover, the corrosion products and bubbles on the surface of RGO@ZIF@SiO 2 /EP (0.7%) sample were the least after 200 h of exposure in salt spray test, further proving its best corrosion protection performance. [Display omitted] • ZIF as a solid corrosion inhibitor is uniformly loaded on the surface of RGO. • Silicon oxide shell can fill the holes left by the decomposition of ZIF. • The RGO@ZIF@SiO 2 hybrids exhibited high corrosion inhibitor loading rate. • The synergistic effect of ZIF@SiO 2 and RGO enhanced the anti-corrosion performance. [ABSTRACT FROM AUTHOR]

Multiwalled carbon nanotubes (MWCNTs) were acidized to get MWCNTs-COOH; the aluminum oxide (Al2O3)-coated MWCNTs hybrid material were prepared by sol–gel method and the result of cladding was verified using x-ray diffraction and scanning electron microscopy. Silane-coupling agent (KH560) was used to modify the hybrid materials. Composite coating with different concentrations of MWCNTs and Al2O3-coated MWCNTs was prepared. The wear resistance of the composite coating was tested by wear tester. The impedance performance and flexibility of Al2O3-coated MWCNTs/epoxy (2 wt%) and MWCNTs/epoxy (2 wt%, composite coating containing 2 wt% nanometer powder) were measured by the electrochemical workstation and mechanical testing equipment (MTS). The results show that the corrosion resistance and wear resistance of the Al2O3-coated MWCNTs/epoxy composite coating have some improvement compared with MWCNTs/epoxy, but a reduction in the flexibility of the Al2O3-coated MWCNTs/epoxy (2 wt%) composite coating. [ABSTRACT FROM PUBLISHER]

MoS2 has been regarded as a promising addition for the preparation of epoxy-based coatings with high anticorrosion ability. However, its dispersion and compatibility remain significant challenges. In the present work, an organic thin layer was well coated on lamellar molybdenum disulfide (MoS2) via a simple modification of 3-aminopropyltriethoxysilane (APTES). The modification of hydrolyzing APTES on lamellar MoS2 effectively improved the dispersity of MoS2 in water-borne epoxy (WEP) and successfully enhanced the compatibility and crosslinking density of MoS2 with WEP. The influence of introducing MoS2-APTES into WEP coating on anticorrosion property for N80 steel was tested by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and salt spray test. The results exhibited that the |Z|0.01Hz value of MoS2-APTES/WEP still reached 3.647 × 107 Ω·cm2 even after the immersion time of 50 days in 3.5 wt.% NaCl solution, showing an extraordinary performance of corrosion resistance. The enhanced anticorrosion performance of composite coating could be resulted from the apparently increased dispersibility and compatibility of MoS2 in WEP. [ABSTRACT FROM AUTHOR]

Tannic acid (TA), as a biodegradable corrosion inhibitor, was used to modify the graphene (Gr) for improving the water-dispersibility of Gr. Further, the polyaniline (PANI) was enwrapped on the vanadium pentoxide (V 2 O 5) surface to increase its conductivity, thus promoting rapid formation of passivation film. Besides, the PANI enwrapped vanadium pentoxide (PV) was self-assembled with the Gr-TA through π-π interaction. Then, the waterborne epoxy coating (WEC) filled with the Gr-TA@PV hybrids were prepared, and the corrosion protection performance of the nanocomposites WEC were investigated through electrochemical and salt spray tests. The results confirmed that the outstanding corrosion protection performance of Gr-TA@PV/WEC derived from the superior barrier property of Gr nanosheets for corrosion agents and its self-healing effect. The self-healing process includes the formation of TA-Fe-TA complex and a passive Fe 2 O 3 / Fe 3 O 4 layer at the interface of coating/substrate. Unlabelled Image • TA as a corrosion inhibitor was used to increase the dispersion of Gr in water. • PANI was enwrapped on the V 2 O 5 surface to increase its conductivity. • The Gr-TA and V 2 O 5 @PANI (PV) were self-assembled through π-π interaction. • The Gr-TA@PV/WEC exhibited superior barrier properties and self-healing effect. [ABSTRACT FROM AUTHOR]

Self-healing coatings, possessing an "active healing" ability to repair physical damage and to prolong the life of coating without external intervention, are of current interest. Herein, a novel self-healing coating, by using aspartic acid intercalated layered double hydroxide (AA-LDH) @ reduced graphene oxide (RGO) as filler within epoxy has been demonstrated. The corrosion protection performance and self-healing ability of composites coatings have been investigated via electrochemical impedance spectroscopy (EIS) and salt spray test. The AA-LDH@RGO/epoxy exhibits excellent corrosion resistance owing to the high barrier properties of RGO for corrosive ions. Moreover, the epoxy loaded with AA-LDH@RGO shows outstanding self-healing performance, attributing to the release of AA from LDH on the basis of the ion exchange performance, thus leading to formation of AA-Fe-AA compounds at the coating/steel interface. The results clarified that the addition of AA-LDH@RGO increases the impedance of the epoxy resin from 6.437 × 106 to 2.112 × 109 Ω cm2, and effectively extends the epoxy coating failure time to 40 days. [ABSTRACT FROM AUTHOR]

In this study, polyethyleneimine (PEI) was first adsorbed on the GO surface, resulting in a positively charged GO/PEI composite. Afterwards, SA and Zn2+ were loaded on the surface of GO/PEI through a facile route to obtain an organic-inorganic hybrids (GPS@Zn). Among them, the gas phase products of SA delayed the progress of the combustion reaction, while the catalytic carbonization of zinc oxide and the high barrier effect of GO effectively improved the thermal insulation efficiency of the char layer. The fire performance test results showed that the backside temperature of GPS@Zn/EP decreased to 161.2 °C after burning for 60 min. The swelling height and swelling ratio of GPS@Zn based EP remained at the highest value compared to the other samples. In addition, the residual char content of EP loaded GPS@Zn was as high as 31.2 %, which lays the foundation for its high thermal insulation performance. The PHRR, THR, SPR and TSP values of GPS@Zn/EP were 420.2 ± 13 kW/m2, 13.2 ± 0.6 MJ/m2,0.078 ± 0.05 m2/s and 1.87 ± 0.05 m2, respectively, which were significantly lower than the other samples, thus proving its best flame retardant and smoke suppressing properties. The carbon residue analysis confirmed that zinc oxide remained in the char layer, which was beneficial to the improvement of its thermal insulation performance and strength. [Display omitted] • PEI, SA, and Zn2+ were self-assembled layer by layer on the GO surface. • Water and carbon dioxide released by SA acted as a gas-phase flame retardant. • Adsorbed zinc ions promoted the formation of char residues during combustion. • The THR and TSP values of GPS@Zn were reduced by 48 % and 60 % compared to pure EP. [ABSTRACT FROM AUTHOR]

A novel flower-like flame retardant was employed to improve the flame retardancy of epoxy resins. Specifically, polydopamine (PDA) was first loaded on the surface of floral Ni-Al layered dimetallic hydroxide (Ni-Al/LDH) to endow it with excellent hydrophilicity and abundant reactive groups. Then, hexachlorocyclotriphosphorus (HCCP) was grafted onto the surface of LDH/PDA to ensure the introduction of a significant amount of P elements, which is essential for enhancing the flame retardancy of the composite. Finally, zinc hydroxystannate (ZHS) was anchored onto the surface of LDH/PDA/HCCP (LDH/PCP) by co-precipitation. The advantage lies in combining the char layer enhancement effect of Ni-Al/LDH, the gas-phase flame retardant and catalytic carbon-forming effect of ZHS to obtain highly efficient nanocomposite fire coatings. The results revealed that the LDH/PCP@ZHS/EP composite coating had the highest residual carbon rate (31.7 %) in the heat loss experiments, which provided the basis for its high thermal insulation performance. Tests on the thermal insulation performance of the coatings found that the backside temperature of LDH/PCP@ZHS/EP (162.6°C) was lower than that of other coatings, which is closely related to the high residual carbon and residual metal oxides. Meanwhile, the LDH/PCP@ZHS/EP specimen has the largest expansion height (34.6 mm), the largest expansion ratio (23.13), and the smallest smoke density (35.7 %), indicating that its expansion height and smoke suppression performance are significantly improved. The microstructure of the expanded char layer showed that the residual carbon was more complete and dense after the combustion of LDH/PCP@ZHS/EP. This also reflects the excellent thermal insulation and flame retardant properties of LDH/PCP@ZHS/EP composite coating. [Display omitted] • Enriched hydroxyl groups of PDA were loaded on the surface of LDH, providing possibilities for its further modification. • HCCP and PDA were co-deposited on the LDH surface to form an efficient P-N- metal element flame retardant system. • ZHS flame retardant in situ growth on the surface of LDH/PCP reduced the aggregation of ZHS nanoparticles. • The combined advantages of ZHS and LDH/PCP effectively enhanced the fire protection ability of composite coatings. [ABSTRACT FROM AUTHOR]

Herein, the ZIF nanoparticles were firstly anchored uniformly on the reduced graphene oxide (RGO) surface, and then a layer of silica was deposited on the surface to avoid the negative impact of the pores generated by the decomposition of the ZIF nanoparticles on the thermal insulation properties. The effect of reduced graphene oxide/zeolitic imidazolate framework-8@silicon oxide (RGO/ZIF@SiO 2) hybrids on the fire performance of the coatings was analyzed by big plate experiments, furnace test, and thermal weight loss test. The results showed that the backside temperature of RGO/ZIF@SiO 2 based intumescent fire-retardant coating (IFR) reached the minimum value (173.9 °C) compared to other samples. The expansion characteristics of the coatings were significantly increased by the addition of nanoadditives. By comparison, RGO/ZIF@SiO 2 /IFR composite coating exhibited the largest expansion height (21.5 mm) and expansion rate (16.28). Moreover, the IFR loaded RGO/ZIF@SiO 2 displayed the highest maximum thermal decomposition temperature (T max , 371.1 °C) and residual char (29.8%), indicating its best fire resistance properties. The cone calorimeter test results illustrated that RGO/ZIF@SiO 2 /IFR had the lowest PHRR (482 ± 21 kW/m2), THR (15.57 ± 0.9 MJ/m2), PSPR (0.10 ± 0.01 m2/m2), TSP (2.01 ± 0.11 m2/m2) and CRR (28.8%) values, indicating its best flame retardant and smoke suppression properties. • ZIF nanoparticles were fixed on the surface of RGO by hydrothermal strategy. • Silicon oxide is deposited on the surface of ZIF to improve its thermal stability • Non-combustible gases released from ZIF retarded the combustion process. • The synergistic effect of ZIF@SiO 2 and RGO enhanced the anti-fire performance. [ABSTRACT FROM AUTHOR]

In this study, the synergistic effect of carbon nanotubes (CNTs) and graphene oxide (GO) on the flame retardant properties of waterborne intumescent epoxy coatings was investigated. Firstly, bio-inspired polydopamine (PDA) was wrapped on the surface of CNTs to increase their water dispersibility and provide them with abundant reactive functional groups. Then, the 3-Aminopropyl triethoxysilane (KH550) was grafted on CNTs/PDA surface. Subsequently, the GO was combined with the modified CNTs by chemical reaction to obtain the GO@M-CNTs hybrids. The results showed that the composite coating with GO@M-CNTs hybrids had better fire retardant performance than the addition of CNTs or GO nanosheets alone. In contrast, the composite coating loaded with 1.5% of GO@M-CNTs hybrids exhibited the lowest backside temperature (168.2 °C), indicating its highest thermal insulation performance. Moreover, the results of the furnace storage experiments displayed that the GO@M-CNTs 1.5% /EP sample exhibited the maximum expansion height (13.7 mm) and expansion rate (10.79) due to the hybrids effectively hindering the escape of the foamed gas into the air. In addition, the GO@M-CNTs 1.5% /EP composite coating exhibited the maximum T max (370.4 °C) and char residue (28.8%) during the TGA test, which resulted in its most excellent fire retardant performance. [Display omitted] • Polydopamine was used to improve the water dispersion stability of CNTs. • GO and CNTs were connected by covalent bond with KH550 as bridge. • The fire retardant performance of the hybrids based coatings was superior to the addition of GO or CNTs alone. • The mechanism of the synergistic effect of GO and CNTs on the char layer was explored. [ABSTRACT FROM AUTHOR]

• Realizing pH response by depositing Cu-BTA complexes on the surface of MIH. • MIH is considered as a transit station, absorbing Cl− ions and releasing MoO 4 2- ions. • The container-based coatings possessed high barrier and dual self-healing properties. • Anticorrosion of WECs improved obviously after incorporating MIHC composites. Smart self-healing coatings with the active healing ability are the current research hotspot in the field of metal corrosion protection. In this work, we designed a novel corrosion protection system of waterborne epoxy. Under alkaline condition, Cu-BTA complexes were deposited on the surface of MoO 4 2− intercalated Mg-Al Layered double hydroxide (MIH) by electrostatic assembly as pH-sensitive gatekeepers. When MIH@Cu-BTA(MIHC) nanosheets were filled into the coatings, the layered structures of Layered double hydroxide(LDH) improved the barrier properties of the coatings to prevent corrosive ions penetration. Meanwhile, the excellent ion exchanges ability of LDH could be used to reduce the concentration of Cl- ions, both of MoO 4 2− ions and BTA could release quickly from MIHC in an acidic environment to achieve the self-healing effect. All of them cooperated to synergistically improve the anti-corrosion performance of the coating. The long-term protective performances and self-healing properties of WECs which loaded nano-containers were evaluated by salt spray test and electrochemical experiment. The impedance results indicate that the addition of MIHC(0.5 wt.%) increases the impedance of pure epoxy coating from 1.579 × 108 to 1.041 × 109 Ω cm2. [ABSTRACT FROM AUTHOR]

In this study, phytic acid -doped polyaniline (PPA) was loaded on the surface of carbon spheres, resulting in a classical C-N-P flame retardant system, that has a beneficial function for the formation of residual carbon. Subsequently, using this phosphorus-nitride carbon sphere (CS/PPA) as a carrier, flower-like Ni-Al-layered double hydroxide (Ni-Al/LDH) were uniformly grown on its surface, thus obtaining a novel nano-fire retardant with a graded structure to heighten the fire-resistant properties of aqueous epoxy resin. Importantly, the intervention of Ni-Al/LDH nanosheets not only imparts a gas-phase fire retardant function to the coating, but also the presence of Ni and Al bimetals can effectively catalyze the formation of more residual carbon in the combustion process. The highest residual carbon (30.7 %) in thermal weight loss experiments of the CS/PPA@Ni-Al/LDH/EP composite coating confirmed this view. Tests on the thermal insulation behavior of coatings illustrated that the backside temperature (168.8 °C) for CS/PPA@Ni-Al/LDH/EP was significantly smaller than that of other coatings, and that this optimum thermal shielding is inextricably linked to the high residual carbon and the residual metal oxides. Furthermore, the CS/PPA@Ni-Al/LDH/EP specimen shown the greatest expansion height (25.1 mm), expansion ratio (19.61) as well as the smallest smoke density rating (39.1 %), proving that its expansion property and smoke suppression were effectively improved. Moreover, the microstructure for the expanded carbon layer demonstrated that the CS/PPA@Ni-Al/LDH filled EP possessed a more complete and dense residual carbon after burning. Moreover, the high degree of graphitization of the residual carbon for CS/PPA@Ni-Al/LDH/EP determined its high thermal stability. The lowest cracked gas phase products and CO release of the CS/PPA@Ni-Al/LDH/EP composite coating during TG-IR testing confirmed its lowest fire toxicity. The development of such a composite flame retardant with a graded structure could help to advance the progress of waterborne intumescent fire coatings. [Display omitted] • Introducing N P compounds into CS surface to overcome the defect of high smoke production. • In situ growth of flower-like LDH on CS/PPA surfaces to achieve composite enhancers with multistage flame retardant effects. • Phosphorus-containing compounds in phytic acid promote the dehydration of polymers into charcoal. • Ni, Al metal oxides effectively promote the formation of residual carbon at high temperature and enhance its stability. [ABSTRACT FROM AUTHOR]

Here, carbon spheres (CS), a carbonaceous spherical material with a wide source and easy preparation, were used as enhanced nano-fillers to reinforce the flame retardancy of aqueous epoxy intumescent coatings. To overcome the defects of CS themselves during combustion, polydopamine (PDA) was co-deposited with adenosine triphosphate (ATP) on its surface to obtain activated carbon spheres with C-N-P structure (CS/PAP), which can contribute to the formation of intumescent char layer. Meanwhile, zinc hydroxystannate (ZHS), as a non-halogen, environmentally friendly, and efficient flame retardant, was introduced to the surface of carbon phosphide spheres to obtain a composite functional hybrid reinforcement (CS/PAP@ZHS). Adiabatic performance tests indicated that the backside temperature of the CS/PAP@ZHS filler-reinforced EP expansion specimen was maintained at the minimum fig. (168.8 °C), confirming its highest resistance to heat penetration. Compared to the CS-based EP, the CS/PAP-loaded EP showed reduced smoke emission, indicating the effectiveness of the PAP intumescent phosphate modification for smoke suppression. By comparison, the CS/PAP@ZHS-based EP showed the largest char residue (29.1 % in N 2 , 12 % in air), expansion height (23.1 mm), and minimal smoke density grade (40.7 %). Additionally, compared with pure EP, the peak heat release rate (PHRR), total heat release rate (THR), peak smoke production rate (PSPR), and total smoke production (TSP) of CS/PAP@ZHS/EP are reduced by 33.3 %, 28.2 %, 37.4 %, and 23.6 % respectively, demonstrating its best fire and smoke suppression properties. [Display omitted] • ATP was introduced into the CS surface by utilizing the high adhesion of PDA. • The combination of CS, PDA, and ATP has constructed an effective C-N-P flame retardant system. • The ZHS endowed the coating with gas-phase flame retardancy and catalytic carbonization effect. • The residual ZS effectively improved the strength and barrier ability of the residual carbon. [ABSTRACT FROM AUTHOR]

Herein, bionic coral-like PANI-loaded graphene oxide (GO@coral-like PANI) nanomaterials were successfully prepared by gas carbon formed by submicron calcium carbonate as a sacrificial template during the polymerization of PANI with graphene oxide. The unique bionic coral-like PANI outer layer not only enhances the passive barrier ability and dispersion stability of the GO nanosheets, but also provides self-healing capability to the composite coating through the ability to promote the oxidation of iron ions to Fe 2 O 3 /Fe 3 O 4 and the loaded corrosion inhibitors (BTA and Ce ions). While the structure, morphology and properties of the GO@PANI/BTA/Ce (GPBC) nanocomposites have been systematically characterized, the barrier and self-healing properties of the composite coatings were tested by electrochemical, salt spray tests and corrosion product elemental analysis. The samples with GPBC exhibited an extended failure time of 30 d and an increased duration of 200 h in the salt spray test compared to pure WEC, as well as self-healing properties after 4 h of coating rupture. The results demonstrated that the WEC loaded with GPBC nanomaterials provides a long-lasting passive barrier effect and self-healing ability. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract High-efficient anti-corrosive epoxy coating, containing homogeneously dispersive graphene (Gr), has been achieved by combining non-covalent and covalent bonds. Tannic acid (TA) has been used as intercalators to disperse Gr in water via π − π non-covalent bond to form Gr-TA hybrids. Consequently, γ-(2,3-epoxypropoxy)propytrimethoxysilane was used to modify the surface of Gr-TA via covalent bond to enhance the interactions between Gr-TA and epoxy. The corrosion resistance properties of the composite Gr-TA/epoxy coatings were tested by electrochemical experiment and salt spray test. The results showed that anti-corrosion properties of Gr-TA-KH560/epoxy composite coatings were hugely enhanced compared with those of the Gr-TA/epoxy and pure epoxy. [ABSTRACT FROM AUTHOR]

While water-based epoxy coatings have been welcomed by the market due to their excellent environmental performance and low volatile organic compounds emission, its poor flame retardancy has led to limited applications. Herein, the catalytic char formation effect of zirconium phenylphosphonate (ZrPP) and the excellent flame retardant properties of layered double hydroxide (LDH) were fully combined to obtain a high-performance composite flame retardant coating. Specifically, polydopamine (PDA) with excellent adhesion properties was encapsulated on the surface of LDH to enhance its dispersibility in water. The introduction of PDA provided abundant active sites for the adsorption of ZrPP precursor cations, which contributed to the uniform loading of ZrPP on LDH to obtain well-structured LDH@PDA@ZrPP (LPZP) hybrids. The synergistic effect of LDH and ZrPP on the flame retardant properties of the epoxy resin matrix was investigated. The LPZP 4% /EP sample showed the lowest backside temperature (173.6 °C), maximum expansion height (25.10 mm) and expansion rate (20.10), proving its highest thermal insulation effect. In the TGA test, the residual char of LPZP 4% /EP increased to 26.8 %, proving the excellent thermal stability of the coating. The SEM images showed that the internal char layer of the composite coating formed a honeycomb network structure, which increased the heat absorption property of the char layer. • PDA encapsulated LDH to improve the dispersion of the material in the epoxy resin. • ZrPP can promote the formation of dense and dense coke layer. • The metal oxides generated by LPZP at high temperatures effectively improve the mechanical strength of the char layer. • The physical barrier and catalytic carbonization effect of LPZP further enhances the insulation performance of the coating. [ABSTRACT FROM AUTHOR]

To address the phenomenon of rapid fire spread in high-rise steel buildings, this paper used the in situ growth method to crystallize sodium metaborate (SMB) on the surface of layered double hydroxide (LDH) and grafted Ti-O onto LDH@SMB hybrid material by hydroxyl action. The synthesized LDH@SMB@Ti (LST) hybrid material was then doped into epoxy resin (EP) to prepare a composite coating. The fire test showed that the LST/EP coating makes the steel plate reach a stable temperature in a shorter time, so that the plate temperature did not continue to rise, and the temperature on the back side of the plate was stabilized at 172.9 °C, which was 87.4 °C lower compared to pure EP. This proves that the LST material gives the coating stronger fire retardant properties upfront and strengthens the continuous insulation ability of the char layer. Cone calorimeter tests showed that the total heat release rate (THR) of LST/EP was reduced by 47.3% and the total smoke release rate (TSR) was reduced by 45.4%, proving the excellent fire and smoke suppression performance of LST/EP. In the expansion performance test, the expansion height and expansion rate of LST/EP reached 29.90 mm and 23.36 respectively, and the expansion of char layer was more uniform. This indicates that the addition of LST hybrid material can improve the mechanical strength of char layer and attenuate the heat transfer rate in the vertical direction. The residual char of LST/EP was 33.2% by thermogravimetric analysis, indicating that the addition of LST could reduce the volatilization of volatile components and improve the thermal stability of EP. [Display omitted] [ABSTRACT FROM AUTHOR]

In recent years, a great deal of research has been devoted to designing smart anti-corrosion coatings with diverse self-healing capabilities, effective passive barrier properties, and long-lasting protection. Herein, the tetraethyl orthosilicate (TEOS) was used as a pH response guardian encapsulated on a BTA-loaded β-cyclodextrin (β-CD) nanocavity shells (CD(BTA)@TEOS), which would be ineffective in acidic environments, thus causing the release of BTA. Meanwhile, the polydopamine (PDA) was coated on the hexagonal boron nitride (h-BN) nanosheets (h-BN@PDA) to enhance its dispersibility and provide reactive sites. Further, the h-BN@PDA-CD(BTA)@TEOS (BPCT) hybrids were synthesized by linking CD(BTA)@TEOS nanocavity shells and h-BN@PDA nanosheets through PDA and KH560 as bridging agents. The dispersion of BPCT in waterborne epoxy coating (WEC) can effectively fill the coating defects and prolong the diffusion path of corrosive media, showing excellent barrier properties due to the excellent barrier properties of h-BN@PDA nanosheets against corrosive media. Meanwhile, the excellent self-healing properties of the composite coating under corrosive conditions were mainly derived from the released BTA and stripped PDA in response to pH variation. The corrosion resistance of the composite coating was tested by electrochemical, salt spray tests and microscopic corrosion morphology, and the self-healing properties of the coating were demonstrated by scratch electrochemistry. The expiration time of the BPCT/WEC sample was extended by 15 d, the persistence time in the salt spray test increased by 100 h, and the self-healing properties appeared after 4 h of coating rupture compared to the control WEC. The results proved that the WEC loaded with BPCT nanocontainers had a high barrier effect along with self-healing function and durable corrosion resistance. [Display omitted] • The h-BN nanosheets block the intrusion of corrosive media and retard the corrosion process. • The improvement of h-BN dispersibility by PDA enhanced the passive barrier performance. • The dual self-healing effect from BTA and PDA enhances the corrosion resistance of the coating. • Long-lasting corrosion protection through BTA released by the pH-responsive of TEOS. • The synergistic effect of passive barrier and self-healing enhanced corrosion resistance. [ABSTRACT FROM AUTHOR]

As a carbon-based flame retardant, carbon microspheres (CMS) not only block heat transfers at low temperature, but also the inert gas produced by its high-temperature decomposition can act as a dilution of combustible gases. However, its barrier effect is limited at high temperature. Herein, CMS were synthesized by a facial hydrothermal method with glucose as raw material. Then, a layer of molybdenum disulfide (MoS 2) nanosheets was uniformly loaded on its surface to obtain a novel CMS@MoS 2 hybrids with core-shell structure, which was used to improve the fire resistance of composite coating. The results showed that the backside temperature of the composite coating with 3% of CMS@MoS 2 hybrids reached the lowest value (173.1 °C), revealing its highest heat shielding effect. Moreover, due to the improvement of the synergistic barrier effect of CMS and MoS 2 nanosheets on gas and heat at high temperature, the EP/CMS@MoS 2 -3.0% coating exhibited the maximum expansion height (16.87 mm) and expansion rate (13.18). Meanwhile, the values of T max (372.9 °C) and carbon residue (30.6%) also reached the maximum, which is due to the catalytic carbon formation effect of Mo atom and the improvement of thermal and mass barrier performance of char layer. Moreover, smoke density tests showed that the EP/CMS@MoS 2 -3.0% had the lowest SDR (36.4%). Further, the EP/CMS@MoS 2 -3.0% exhibited the lowest PHRR (577 ± 13 kW/m2), THR (18.71 ± 0.9 MJ/m2), PSPR (0.118 ± 0.02 m2/m2) and TSP (2.80 ± 0.07 m2/m2) values, demonstrating its excellent flame retardant and smoke suppression properties. [Display omitted] • CMS@MoS 2 core-shell structure was synthesized by facile hydrothermal strategy. • The introduction of CMS improved the amount of residual carbon after combustion. • Residual MoS 2 nanosheets enhanced the strength and fire resistance of the char layer. • The synergistic effect of CMS and MoS 2 further enhanced the thermal insulation performance of char. [ABSTRACT FROM AUTHOR]

An effective method to enhance the flame retardant capability of intumescent fire retardant (IFR) coatings by constructed a two-dimensional/two-dimensional (2D/2D) hybrid with good composition and microstructure. Herein, g-C 3 N 4 @PDA (CNP) was firstly obtained by loading graphite phase carbon nitride (g-C 3 N 4) with bio-inspired polydopamine (PDA). Subsequently, a novel CNP@Mo hybrids was successfully prepared by loading molybdenum disulfide onto the CNP surface via a simple one-step hydrothermal method. Then, the obtained CNP@Mo was added to the IFR coating as a synergist to improve the flame resistance. Results indicated that the addition of 2 wt% CNP@Mo to the coating effectively accelerated the formation of the char layer and reinforced its thermal insulation properties. The CNP@Mo/EP sample exhibited the lowest backside temperature (179.6 ℃), the highest expansion ratio (10.53) and the most residual char (30.7%) by fire performance test, furnace test and TGA test. The combustion performance of the IFR coatings was investigated by cone calorimeter, and the results showed that the CNP@Mo hybrids based composite coating exhibited the lowest heat release rate (HRR), total heat release rate (THR), and total smoke production value (TSP). The mechanism investigations showed that the physical barrier effect and catalytic carbonization produced by CNP@Mo hybrids during the combustion process are the main reasons for the improved flame retardancy of epoxy coatings. [Display omitted] • The free radical scavenging effect of PDA can enhance the oxidation resistance. • The 2D/2D heterostructure between g-C 3 N 4 and MoS 2 shows excellent thermal stability at high temperature. • Molybdenum atoms favor the formation of carbon, thus promoting char layer formation. • CNP@Mo based IFR coatings exhibited excellent flame retardant performance. [ABSTRACT FROM AUTHOR]

Inspired by the multifunctional adhesion ability of poly dopamine (PDA), ZrO 2 and aluminum magnesium hydroxide (LDH) were combined by PDA, which increased the function of this material in intumescent fire retardant (IFR) coatings. Briefly, PDA was coated on the surface of LDH to improve its dispersion stability in water. Then, the high thermal stability ZrO 2 nanoparticles were immobilized in situ on the LDH/PDA surface to improve the strength and temperature resistance of the char layer by a hydrothermal strategy. The fire protection performance of LDH@PDA@ZrO 2 (LPZ) modified intumescent fire retardant (IFR) coatings was performed by large plate method, thermogravimetric analysis (TGA) and furnace experiments. From the results, the IFR coating loaded with 2.5% LPZ exhibited the lowest backside temperature and the highest heat insulation, which reached 177.9 °C and 64.42, respectively. Besides, the coating exhibited the greatest expansion height (23.65 mm) and expansion rate (18.92), which is significantly higher than that of other coatings. Moreover, the maximum thermal degradation temperature (T max) and residual char of LPZ 2.5% /EP were significantly higher than other samples. Further, the LPZ 2.5% /EP based sample indicated the lowest smoke density rating (SDR) due to its excellent smoke suppression performance. The residual carbon analysis showed that ZrO 2 nanoparticles and LDH nanosheets remained in the char layer during the combustion process, which is beneficial to increase the strength of the char layer and its barrier effect on heat and oxygen. [Display omitted] • The free radical scavenging effect of PDA enhanced the oxidation resistance of coating. • PDA encapsulated LDH to improve the dispersion of the material in the epoxy resin. • ZrO 2 was introduced to improve the strength and compactness of the char layer. • The synergistic effect of ZrO 2 and PDA further enhanced the thermal insulation performance of char. [ABSTRACT FROM AUTHOR]

Inorganic fillers are generally used as synergistic agent in waterborne epoxy resin intumescent fire-retardant coating. To enhance the flame retardant properties of the coating, modified hexagonal boron nitride (h-BN) was introduced. Firstly, the h-BN nanosheets were modified with polydopamine (PDA) through the strong π-π non-covalent interaction between the hexagonal structure of boron nitride and aromatic dopamine molecules. Then, the Ti-O compounds was formed on the surface of the hybrids by covalent modification, which can generate titanium dioxide (TiO 2) and titanium pyrophosphate (TiP 2 O 7) at high temperature to enhance the strength of the char layer. The enhancement of the synthetic material (BPT) was evaluated by fire performance measurements and thermogravimetric analysis (TGA). The structure and morphology of the char layer after the fire test were analyzed by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) techniques. The results showed that the introduction of BPT hybrids effectively enhanced the strength and oxidation resistance of the char layer and improved the barrier effect to heat and oxygen. Compared with EP, the back temperature of BPT 3% /EP steel plate decreased from 259 ℃ to 198 ℃, the expansion ratio increased from 3.04 to 8.91, and the residual char increased from 20.5% to 29.1%. [Display omitted] • The free radical scavenging effect of PDA can enhance the oxidation resistance. • Grafting of organic titanium onto h-BN@PDA improved coatings' thermal stability. • The introduction of Ti element did not reduce the dispersion of the hybrids. • h-BN@PDA@Ti based IFR coatings exhibited excellent flame retardant performance. [ABSTRACT FROM AUTHOR]

Firstly, the bio-inspired polydopamine (PDA) was coated on the surface of carbon nitride (CN), then used it (CNP) as nano-dispersant to improve the dispersion of graphene (Gr) in water on the basis of π-π interaction. After that, the KH560 was further grafted on the CNPG surface to improve the compatibility between inorganic hybrids and epoxy resin. The results of large plate experiments showed that the backside temperature of composite IFR coating containing CNPG@Si hybrids was significantly lower than that of other samples. Meanwhile, its expansion height after furnace test reached the maximum value (17.8 mm), which was greatly improved compared with the pure epoxy coating. Further, the maximum thermal decomposition temperature and the amount of char residue for the CNPG@Si/EP sample were significantly enhanced through the TGA test result. Besides, CNPG@Si based sample showed the lowest smoke density rating (SDR) due to its excellent smoke suppression performance. From the analysis of the morphology and composition of the char layer for CNPG@Si based sample, it can be seen that the introduction of Gr and CN increased the compactness of the char layer, and silicon network structures remained in the char layer after combustion, which effectively increases its strength and heat insulation effect. [Display omitted] • CN and Gr were successfully combined by using PDA as an intermediary. • The combination of CN and Gr enhances the thermal barrier effect of coating. • The introduction of PDA improves the antioxidant function of char layer. • Modification of KH560 increases the thermal insulation properties of char layer. [ABSTRACT FROM AUTHOR]

Firstly, polyaniline (PANI) was used to improve dispersibility of graphene (Gr) in water through π-π interactions. Then, the obtained Gr/PANI products was further decorated with the epoxy based polyhedral oligomeric silsesquioxane (EPOSS) to enhance the hydrophobic properties of hybrid materials and compatibility with epoxy resins, thus leading to the increase of corrosion protection properties. From the wettability test results, the contact angle of the cross section of the composite coating reached up to 112.7 ° after grafting EPOSS, indicating that the hydrophobicity of the coating was improved significantly. Besides, the tensile strength of Gr/PANI@EPOSS/epoxy (0.7%) increased to 25.6 MPa, which proves the increase of interface force due to the introduction of epoxy group. The results of electrochemistry test illustrated that the impedance of Gr/PANI@EPOSS/epoxy (0.7%) is still as high as 2.79×107 Ω cm2 after 60 days of immersion, which is much higher than that of other samples. [ABSTRACT FROM AUTHOR]

• Fabricating VPC composite by wrapping of PANI on V 2 O 5 and deposition of Fe-TA. • The composite has ternary effects of passivation, active inhibition and barrier. • Anticorrosion of epoxy coating improved obviously after incorporating VPC composites. • Synergism of passivation and pH-triggered inhibition to realize self-healing of coatings. Inspirations from nature have led to extensive developments in metal passivation and smart self-healing technologies toward metal corrosion protection. Integration of both intriguing features helps to achieve high-efficiency corrosion inhibition protection. In this study, we designed a novel anticorrosion system composed of waterborne epoxy (WEP) and VPC nanofillers (V 2 O 5 modified by polyaniline and tannic acid complexes) (V 2 O 5 @PANI@Fe-TA (3)). Among them, the PANI-modified V 2 O 5 particles have dual roles as oxidation passivation protection and a passive barrier. The tannic acid corrosion inhibitor loaded onto the particles can be released under pH stimulation to provide appropriate activity inhibition function. This dual, synergistic self-healing protection coupled with a robust film barrier was the main reason for the strong anticorrosion properties of the coating system. In a specific experiment, the anticorrosion performance of the composite coatings was verified by electrochemical and salt spray tests. Results revealed that the value of |Z| 10mHz for VPC/WEP composite coating was still higher than 108 Ω/cm2 after 80 d of immersion as compared to those of the pure WEP. Interestingly, the VPC/WEPs also exhibited a significant self-healing effect when the corrosive medium reached the metal/coating interface through defects or artificial scratches. This is due to the synergistic protective effect of metal passivation and activity inhibition, which enhanced the anticorrosion properties of the coating system. [ABSTRACT FROM AUTHOR]

• The dispersing property of modified g-C 3 N 4 in water was dramatically enhanced. • Compatibility of g-C 3 N 4 in epoxy was notably improved via the modification. • The corrosion resistance of g-C 3 N 4 @SiO 2 composite coating enhanced sharply. In this work, a series of waterborne epoxy coatings containing g-C 3 N 4 @SiO 2 composites were developed to evaluate the anticorrosion property on mild steel. The SiO 2 nanoparticles precipitated on g-C 3 N 4 sheets were fabricated via a facile sol-gel method applying tetraethoxysilane (TEOS) as precursor. With the SiO 2 served as functionalized spacer between g-C 3 N 4 sheets, the dispersibility of modified g-C 3 N 4 sheets in epoxy matrix was notably strengthened. Especially, the g-C 3 N 4 sheets functionalized with SiO 2 endowed improved interfacial interaction bonding and compatibility between g-C 3 N 4 @SiO 2 and epoxy, leading to the significant increase in anticorrosion properties. The characterizations of g-C 3 N 4 @SiO 2 were investigated adequately, and scanning electron microscopy (SEM) was applied to prove the predominant dispersing performance of g-C 3 N 4 @SiO 2 in epoxy coating. Furthermnore, to confirm effect of g-C 3 N 4 @SiO 2 nanocomposites on the anticorrosion and barrier performance of waterborne epoxy, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and salt spray test were conducted to estimate corrosion resistances of the g-C 3 N 4 @SiO 2 /epoxy. The obtained data revealed that the |Z| 0.01Hz value of g-C 3 N 4 @SiO 2 coating increased by 969 % compared with neat epoxy coating. Additionally, the 0.3 wt.% additive amount of g-C 3 N 4 @SiO 2 was confirmed to provide the best shielding effect in epoxy coating, attaining the highest corrosion resistance among the composite coatings. [ABSTRACT FROM AUTHOR]

• The h-BN was co-modified by mechanical exfoliation and chemical modification. • The PEI-BNNS/EP exhibits a superior and long-term anticorrosion performance. • The PEI enhances the crosslink density of EP and reduces the defects of coating. The hexagonal boron nitride (h-BN) has extensive promise for metal corrosion protection due to its good impermeability to gas and liquid. However, the practical application of h-BN in polymer composites is limited by surface incompatibility. Herein, we prepared a homogeneous dispersion of h-BN in water-borne epoxy (EP) matrix by mechanical exfoliation and chemical modification, in which the h-BN powder was ultrasonic to obtain partially hydroxylated BN and the products were modified with water-soluble branched poly-ethyleneimine (PEI) via Lewis acid-base interaction. The electrochemical test (EIS and potentiodynamic polarization) and salt spray test in NaCl solution were used to analyze the corrosion resistance performance of composite coatings. The results show that PEI-BNNS/EP coating has superior and long-term anticorrosion performance for P110 mild steel. The impedance modulus (Z f = 0.01 Hz) of PEI-BNNS/EP still has 6.63 × 107 Ω cm2 after 70 days immersion in the 3.5 wt. % NaCl solution. The PEI has an important role for enhancing the anticorrosion property of PEI-BNNS/EP coating, which increases the dispersibility and compatibility of h-BN in EP and the crosslink density of epoxy resin. Our study gives a strategy for the preparation of easy dispersion h-BN nanosheets in large quantities, thus broadening its practical application in the polymer material field. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride (h-BN) has great promise for metal corrosion due to its good impermeability to gas and liquid. However, it is difficult for h-BN to disperse in water-borne epoxy (WBE) matrix owing to its nature hydrophobicity. In this work, h-BN was non-covalently modified by graphene oxide (GO) to enhance the compatibility of h-BN for WBE. And the GO/h-BN composite was characterized by transmittance electron microscopy (TEM), Raman spectroscopy, UV–vis absorbance spectroscopy and X-ray photoelectron spectroscopy (XPS). The corrosion protection and barrier performance of GO/h-BN/WBE were evaluated by electrochemical impedance spectroscopy (EIS) and salt spray test, which indicated that the composite coating with 0.3 wt. % GO/h-BN (1:1 w/w) additive exhibited excellent barrier and corrosion protection properties owing to the synergistic impermeable performance of h-BN and GO. [ABSTRACT FROM AUTHOR]

• The PDA layers as a novel pH-sensitive gatekeeper for BTA loaded HNTs system. • The GO and HNTs were self-assembled through π-π interaction between GO and PDA. • The GO@PBH/WEC exhibited superior barrier properties owing to adding of GO. • The GO@PBH/WEC presented self-healing effect owing to existence of BTA and PDA. Bio-inspired dopamine have attracted immense scientific interest in the surface modification field due to the high bio-adhesive properties for varies substrate. Herein, the polydopamine (PDA) was used as a novel pH-response gatekeeper to be coated on the BTA-loaded HNTs hybrids (PBH) via conventional polymerization reaction (Tris HCl/pH=8.5), which can be destroyed in an acidic environment resulting in release of BTA. Further, the as prepared PBH were self-assembled with graphene oxide (GO) through π-π* interaction between GO and PDA. The waterborne epoxy coating (WEC) loaded with GO@PBH possessed superior barrier properties owing to the excellent shielding performance of GO nanosheets against the corrosive ions. The dual self-healing effect of GO@PBH based WEC for the carbon steel substrate mainly originated from release of BTA during corrosion process and the formation of complex between catechol of the damaged PDA polymer network and Fe3+. The barrier and self-healing properties of the composite coating were tested by electrochemistry and neutral salt spray test. The results prove that the WEC loaded with GO@PBH hybrids possesses superior barrier properties for the corrosion medium and outstanding self-healing effect as the corrosive ions reached the metal/coating interface. [ABSTRACT FROM AUTHOR]

• The g-C 3 N 4 nanosheets were prepared through direct thermal oxidation method. • The g-C 3 N 4 nanosheets has been used for the first time to disperse Gr. • The corrosion resistance of Gr/g-C 3 N 4 /epoxy composites coating were characterized. • The cross section morphology of the composite coating were analyzed by SEM. The application of graphene (Gr) in waterborne coatings is restricted owing to its strong hydrophobic properties. Herein, graphitic (g)-C 3 N 4 , also with good barrier properties, has been used for the first time to disperse Gr in epoxy solution via simple ultrasonic vibration. The morphologies and structures of g-C 3 N 4 and Gr/g-C 3 N 4 were characterized through FT-IR, XRD, XPS, UV–vis absorption spectra, TEM and Raman spectra. Corrosion resistance performances of the g-C 3 N 4 /epoxy and Gr/g-C 3 N 4 /epoxy nanocomposites coatings were evaluated by electrochemical impedance spectroscopy (EIS) and salt spray tests. Gr/g-C 3 N 4 /epoxy nanocomposites coating exhibits improved anti-corrosion performance in contrast to g-C 3 N 4 /epoxy coating due to enhanced barrier performances. [ABSTRACT FROM AUTHOR]

In this work, the hydrophilic organic films were successfully coated on g-C 3 N 4 nanosheets through facile co-modification of dopamine (DA) and silane coupling agent (KH560). The co -modification of polydopamine (PDA) and KH560 on lamellar g-C 3 N 4 greatly enhanced dispersion of g-C 3 N 4 in aqueous solution and dramatically improved the compatibility and interfacial interaction with waterborne epoxy. The effect of incorporating modified g-C 3 N 4 nanosheets into waterborne epoxy on anticorrosion performance for P110 steel substrates were demonstrated through electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and salt spray test. The results revealed that the |Z| 0.01Hz value and percentage coating resistance (R c) gain (η c %) of nanocomposite coating increased by 977% and 90.72% with the addition of modified g-C 3 N 4 nanosheets in comparison with pure waterborne epoxy coating, exhibiting outstanding anticorrosion abilities. The reinforced anticorrosion performances of nanocomposite coating could be attributed to the notable shielding effect and well dispersibility of modified g-C 3 N 4 nanosheets. A novel well-dispersed g-C 3 N 4 @(PDA + KH560) is successfully fabricated through the co-modification of PDA and KH560, which significantly enhances the corrosion protection performance of waterborne epoxy in comparison with g-C 3 N 4. Unlabelled Image • Co-modification of PDA and KH560 was firstly used to modify g-C 3 N 4 nanosheet. • Dispersion of g-C 3 N 4 in waterborne epoxy was notably improved via the co-modification. • The corrosion resistance of g-C 3 N 4 @(PDA + KH560) coating enhanced sharply. [ABSTRACT FROM AUTHOR]