CN109608985B - Anticorrosive coating capable of being automatically repaired and preparation method thereof - Google Patents
Anticorrosive coating capable of being automatically repaired and preparation method thereof Download PDFInfo
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- CN109608985B CN109608985B CN201811499216.1A CN201811499216A CN109608985B CN 109608985 B CN109608985 B CN 109608985B CN 201811499216 A CN201811499216 A CN 201811499216A CN 109608985 B CN109608985 B CN 109608985B
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- C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
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Abstract
The invention provides an anticorrosive coating capable of being automatically repaired, which comprises the following parts: 0.5-5 parts of stimulus responsive mesoporous silica loaded with corrosion inhibitor and 95-99.5 parts of resin condensate. The anticorrosive coating provided by the invention has double stimulation responsiveness to acid and a reducing agent, and can realize automatic repair. When the coating is damaged, a local microenvironment is changed, under the stimulation of external acid or a reducing agent (such as sulfide ions), stimulation-responsive mesoporous silica shell polymer N-tert-butylcarbonyl loaded with a corrosion inhibitor in the coating is hydrolyzed to leave (under the stimulation of acid) or disulfide bonds are broken (under the stimulation of the reducing agent), the shell polymer is subjected to hydrophobic-hydrophilic conversion, and then mesoporous silica pore channels are exposed, and the loaded corrosion inhibitor is quickly released to form a protective film, so that the corrosion can be effectively inhibited.
Description
Technical Field
The invention belongs to the technical field of high-molecular anticorrosive coating materials, and particularly relates to an anticorrosive coating capable of being automatically repaired and a preparation method thereof.
Background
The corrosion problem of metal materials is spread in various fields of national economy, so that huge waste and economic loss on resources are caused, the total corrosion cost of China per year exceeds 2.1 trillion yuan, and the total corrosion cost accounts for about 5 percent of the total value of national production.
Among all the anticorrosion measures, the anticorrosion coating is most widely used due to the advantages of simple operation, wide application, low cost and the like. The organic anti-corrosion coating isolates the metal matrix from corrosive media such as moisture, oxygen, ions and the like through the physical shielding effect, and inhibits the corrosion cathode-anode reaction, thereby preventing the corrosion electrochemical reaction. However, during service and transportation, the coating is inevitably damaged by various external conditions, so that breakage and cracking are generated. Without timely and effective repair, these defects can lead to a significant reduction in the protective effect of the coating on the metal substrate and in the adhesion of the coating. At present, the damaged coating is mainly repaired or replaced manually, the process is complicated, and the manufacturing cost is high. By using intelligent materials, the coating has the corrosion prevention function and the capability of self-repairing damage, is beneficial to prolonging the service life of the coating, has great economic value and development space, and is one of the most important research directions in the field of corrosion protection at home and abroad in recent years.
The self-repairing anticorrosive coating can restore the original anticorrosive function automatically or under certain conditions after being damaged by external force or environment, and is a novel intelligent protective material. In recent years, the coating technology is closely linked with the development of material science, various functional coatings are continuously emerged along with the continuous progress of the material science, and under the background, the self-repairing anticorrosive coating is rapidly developed in theoretical research and practical application. The existing coating is usually repaired by self-repairing of embedded film forming materials or corrosion inhibitors or repairing stimulated by external conditions.
Shchukin et al (adv. Mater. 2006, 18: 1672-. When the coating is damaged, the local pH changes rapidly, causing the polyelectrolyte layer of the nanocontainer to break apart, releasing the encapsulated corrosion inhibitor BTA. The corrosion inhibitor forms a thin adsorption layer on the surface of the corrosion site metal, so that the surface of the metal is passivated again, and the self-repairing function is achieved. Patent 201810345588.2 discloses a thermal response composite self-repairing coating and a preparation method thereof, wherein the coating is composed of epoxy resin, an epoxy curing agent, a polycaprolactone microsphere shell material and a corrosion inhibitor. Wherein the mass ratio of the microsphere shell material to the corrosion inhibitor is 3: 1.5-2.5, and the microspheres account for 2-30% of the mass of the coating. The coating has multiple repairing performance, and the coating is recovered to moisture, oxygen and Cl after the coating defects are self-repaired-And the shielding capability of corrosive media. In thatXiang et al (plating and coating, 2013,32: 72-75) add hydrotalcite as corrosion inhibitor in epoxy resin in a weight ratio of 20%, cure to form a film on the surface of magnesium alloy, and the coating still has good corrosion resistance after being soaked in 3.5% sodium chloride solution for 70 days. However, the amount of the nanoparticles in the anticorrosive coating is large, the compatibility with the coating is poor, and the integrity of the coating is easily damaged.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide an automatically repairable anticorrosive coating which has good compatibility with a coating and can keep the integrity of the coating, and a preparation method thereof.
The object of the invention is achieved in the following way:
an automatically repairable anticorrosive coating comprises the following parts
(1) 0.5-5 parts by weight of corrosion inhibitor-loaded stimuli-responsive mesoporous silica
(2) 95-99.5 parts by weight of resin condensate.
The resin cured product is an epoxy resin cured product formed by curing epoxy resin, an epoxy curing agent and water.
The epoxy resin is bisphenol A epoxy resin, and the epoxy curing agent is polyether amine D230 and n-decylamine.
The resin cured product is a polyurethane cured product formed by curing hydroxyl-containing resin, an isocyanate curing agent and water.
The stimulus-responsive mesoporous silica loaded with the corrosion inhibitor consists of the corrosion inhibitor and the stimulus-responsive mesoporous silica, wherein the corrosion inhibitor is positioned in a pore passage structure of the stimulus-responsive mesoporous silica, and the loading amount of the corrosion inhibitor is 5-10 wt%.
The corrosion inhibitor is at least one of benzotriazole, methylbenzotriazole, mercaptobenzothiazole and 8-hydroxyquinoline.
The stimulus-responsive mesoporous silica has a core-shell structure, the core is mesoporous silica, the shell layer is a macromolecule with responsiveness to a reducing agent and acid, and a side chain in the macromolecule contains N-tert-butylcarbonyl and a disulfide bond.
The high molecular poly (N-tert-butylcarbonylcystamine methacrylamide) (PMABC).
The preparation method of the self-repairing anticorrosive coating comprises the following steps:
(1) preparing mesoporous silica as a nano container;
(1a) in an alkaline aqueous solution, dodecyl trimethyl ammonium bromide is used as a surfactant, tetraethyl oxysilane is used as a silicon source, and a sol-gel method is adopted to prepare mesoporous silica microspheres;
(1b) in an organic solvent, glycidyl ether propyl trimethoxy silane is used as a silane coupling agent to introduce epoxy groups on the surface of the mesoporous silica microsphere;
(1c) then in an acidic alcohol solution, the epoxy groups are subjected to ring opening and converted into hydroxyl groups, and meanwhile, the surfactant in the pore structure is also removed, so that hydroxyl-modified mesoporous silica microspheres (MSN-OH) are obtained;
(2) preparing stimulus-responsive mesoporous silica, and endowing the stimulus-responsive mesoporous silica with stimulus responsiveness;
(2a) carrying out esterification reaction on hydroxyl-modified mesoporous silica microspheres (MSN-OH) and a carboxyl-containing chain transfer reagent (RAFT reagent), and introducing dithiobenzoate groups on the surfaces of the mesoporous silica to obtain dithiobenzoate-modified mesoporous silica microspheres (MSN-RAFT);
(2b) taking dithiobenzoate-modified mesoporous silica microspheres (MSN-RAFT) as a chain transfer agent, performing reversible addition-fragmentation chain transfer (RAFT) polymerization on functional monomers on the surface of mesoporous silicon, and grafting a stimulus-responsive polymer chain segment to the surface of the mesoporous silica to obtain the stimulus-responsive mesoporous silica; the functional monomer is N-tert-butylcarbonyl cystamine methacrylamide (MABC for short);
(3) loading of corrosion inhibitor: dispersing the stimuli-responsive mesoporous silica and the corrosion inhibitor in tetrahydrofuran, fully adsorbing for more than 12 hours, centrifugally separating, cleaning and drying; the weight ratio of the stimulus responsive mesoporous silica to the corrosion inhibitor is 1: (0.3-1): 1;
(4) the stimulation responsive mesoporous silica loaded with the corrosion inhibitor is uniformly mixed with the resin condensate and then coated on the surface of the metal to form an anticorrosive coating.
The preparation method of the automatically repairable anticorrosive coating comprises the following steps:
(1) preparing mesoporous silica as a nano container;
(1a) the method comprises the following steps Dissolving a certain amount of dodecyl trimethyl ammonium bromide and sodium hydroxide in water to obtain an alkaline aqueous solution; slowly dripping tetraethyl oxysilane into the alkaline aqueous solution, and reacting for 4-6h at constant temperature under stirring; carrying out centrifugal separation, washing and drying to obtain mesoporous silica microsphere MSN;
the concentration of dodecyl trimethyl ammonium bromide in the alkaline aqueous solution is 2-6 g/L, the concentration of sodium hydroxide is 1-2 g/L, and the volume ratio of tetraethyl oxysilane to the aqueous solution is (1-5): 100, the reaction temperature is 70-90 ℃;
(1b) the method comprises the following steps Dispersing the mesoporous silica microsphere MSN in a toluene solution, dropwise adding a silane coupling agent-glycidyl ether propyl trimethoxy silane, carrying out reflux reaction for more than 12h, carrying out centrifugal separation, washing and drying to obtain an epoxy group modified mesoporous silica microsphere (MSN-epoxy);
the weight ratio of the mesoporous silica microspheres to the glycidyl ether propyl trimethoxy silane is (0.5-2): 1;
(1c) the method comprises the following steps Dispersing epoxy group modified mesoporous silica microspheres (MSN-epoxy) in a methanol/hydrochloric acid mixed solution (the concentration of hydrochloric acid in the solution is 1-3 mol/L), performing reflux reaction overnight, performing centrifugal separation, washing and drying to obtain hydroxyl group modified mesoporous silica microspheres (MSN-OH); the surfactant dodecyl trimethyl ammonium bromide is also removed while the epoxy group is converted into the hydroxyl group;
(2) preparing stimulus-responsive mesoporous silica, and endowing the stimulus-responsive mesoporous silica with stimulus responsiveness;
(2a) the method comprises the following steps Ultrasonically dispersing hydroxyl-modified mesoporous silica microspheres (MSN-OH) into dichloromethane, adding a carboxyl-containing chain transfer reagent, namely 4-cyanovaleric acid dithiobenzoate (CTP), a catalyst, namely 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride and 4-dimethylaminopyridine, stirring for reacting for 12 hours, centrifugally separating, washing and drying to obtain dithiobenzoate-modified mesoporous silica microspheres (MSN-RAFT);
the weight ratio of 4-cyano valeric acid dithiobenzoate (CTP) to mesoporous silica microspheres is (0.5-2.0): 1;
(2b) the method comprises the following steps Dispersing or dissolving a functional monomer N-tert-butylcarbonyl cystamine methacrylamide, dithiobenzoate-modified mesoporous silica microsphere MSN-RAFT and a thermal initiator in tetrahydrofuran, heating for polymerization reaction for more than 12 hours, centrifugally separating, washing and drying to obtain stimulus-responsive mesoporous silica MSN-PMABC;
the weight ratio of the functional monomer N-tert-butylcarbonyl cystamine methacrylamide to the dithiobenzoate modified mesoporous silica microsphere is (2-5): 1, the polymerization temperature is 50-80 ℃.
(3) Loading of corrosion inhibitor: dispersing the stimuli-responsive mesoporous silica and the corrosion inhibitor in tetrahydrofuran, fully adsorbing for more than 12 hours, centrifugally separating, cleaning and drying; the weight ratio of the stimulus responsive mesoporous silica to the corrosion inhibitor is 1: (0.3-1);
(4) the stimulation responsive mesoporous silica loaded with the corrosion inhibitor is uniformly mixed with the resin condensate and then coated on the surface of the metal to form an anticorrosive coating.
Compared with the prior art, the invention has the beneficial effects that:
(1) the anticorrosive coating provided by the invention has double stimulation responsiveness to acid and a reducing agent, and can realize automatic repair. When the coating is damaged, a local microenvironment is changed, under the stimulation of external acid or a reducing agent (such as sulfide ions), stimulation-responsive mesoporous silica shell polymer N-tert-butylcarbonyl loaded with a corrosion inhibitor in the coating is hydrolyzed to leave (under the stimulation of acid) or disulfide bonds are broken (under the stimulation of the reducing agent), the shell polymer is subjected to hydrophobic-hydrophilic conversion, and then mesoporous silica pore channels are exposed, and the loaded corrosion inhibitor is quickly released to form a protective film, so that the corrosion can be effectively inhibited.
(2) The silica encapsulates the corrosion inhibitor, which can solve the compatibility problem of the corrosion inhibitor and the coating.
(3) The surface of the silicon dioxide is introduced with a high molecular chain segment, so that the compatibility of the silicon dioxide particles and the coating can be enhanced.
Drawings
FIG. 1 is a schematic diagram of the preparation of stimuli-responsive mesoporous silica and the chemical structure of the main reagents; MSN-OH: hydroxyl-modified mesoporous silica microspheres; CTP: 4-cyanovaleric acid dithiobenzoate; MSN-RAFT: dithiobenzoate modified mesoporous silica microspheres; MSN-PMABC: the shell layer of the stimuli-responsive mesoporous silicon dioxide is PMABC; PMABC: poly (N-tert-butylcarbonylcystamine methacrylamide); MABC: n-tert-butylcarbonylcystamine methacrylamide.
FIG. 2 shows the release of the corrosion inhibitor in the reduction stimulation and control group when MSN-PMABC is used as the corrosion inhibitor carrier.
FIG. 3 shows the release of the corrosion inhibitor at different pH values when MSN-PMABC is used as the corrosion inhibitor carrier.
FIG. 4 is a schematic diagram of the stimulus-responsive change of the corrosion inhibitor and the release mechanism of the corrosion inhibitor.
FIG. 5 is a schematic view of a self-healing anticorrosion coating; 1. the anticorrosive coating can be automatically repaired; 2. a corrosion inhibitor-loaded stimuli-responsive mesoporous silica; 3. a base resin cured product; 4. a metal substrate.
FIG. 6 is A of the results of electrochemical impedance spectroscopy for corrosion protection of coatings.
FIG. 7 is B of the results of electrochemical impedance spectroscopy for corrosion protection of the coating.
Detailed Description
The invention is further described below with reference to examples (figures):
the preparation schematic diagram of the stimuli-responsive mesoporous silica and the chemical structure of the main reagent are shown in fig. 1.
An automatically repairable anticorrosive coating comprises the following parts
(1) 0.5-5 parts by weight of corrosion inhibitor-loaded stimuli-responsive mesoporous silica
(2) 95-99.5 parts by weight of resin condensate.
The resin cured product is an epoxy resin cured product formed by curing epoxy resin, an epoxy curing agent and water.
The epoxy resin is bisphenol A epoxy resin, and the epoxy curing agent is polyether amine D230 and n-decylamine.
The resin cured product is a polyurethane cured product formed by curing hydroxyl-containing resin, an isocyanate curing agent and water.
The stimulus-responsive mesoporous silica loaded with the corrosion inhibitor consists of the corrosion inhibitor and the stimulus-responsive mesoporous silica, wherein the corrosion inhibitor is positioned in a pore passage structure of the stimulus-responsive mesoporous silica, and the loading amount of the corrosion inhibitor is 5-10 wt%.
The corrosion inhibitor is at least one of benzotriazole, methylbenzotriazole, mercaptobenzothiazole and 8-hydroxyquinoline.
The stimulus-responsive mesoporous silica has a core-shell structure, the core is mesoporous silica, the shell layer is a macromolecule with responsiveness to a reducing agent and acid, and a side chain in the macromolecule contains N-tert-butylcarbonyl and a disulfide bond.
The high molecular poly (N-tert-butylcarbonylcystamine methacrylamide) (PMABC).
The preparation method of the self-repairing anticorrosive coating comprises the following steps:
(1) preparing mesoporous silica as a nano container;
(1a) in an alkaline aqueous solution, dodecyl trimethyl ammonium bromide is used as a surfactant, tetraethyl oxysilane is used as a silicon source, and a sol-gel method is adopted to prepare mesoporous silica microspheres;
(1b) in an organic solvent, glycidyl ether propyl trimethoxy silane is used as a silane coupling agent to introduce epoxy groups on the surface of the mesoporous silica microsphere;
(1c) then in an acidic alcohol solution, the epoxy groups are subjected to ring opening and converted into hydroxyl groups, and meanwhile, the surfactant in the pore structure is also removed, so that hydroxyl-modified mesoporous silica microspheres (MSN-OH) are obtained;
(2) preparing stimulus-responsive mesoporous silica, and endowing the stimulus-responsive mesoporous silica with stimulus responsiveness;
(2a) carrying out esterification reaction on hydroxyl-modified mesoporous silica microspheres (MSN-OH) and a carboxyl-containing chain transfer reagent (RAFT reagent), and introducing dithiobenzoate groups on the surfaces of the mesoporous silica to obtain dithiobenzoate-modified mesoporous silica microspheres (MSN-RAFT);
(2b) taking dithiobenzoate-modified mesoporous silica microspheres (MSN-RAFT) as a chain transfer agent, performing reversible addition-fragmentation chain transfer (RAFT) polymerization on functional monomers on the surface of mesoporous silicon, and grafting a stimulus-responsive polymer chain segment to the surface of the mesoporous silica to obtain the stimulus-responsive mesoporous silica; the functional monomer is N-tert-butylcarbonyl cystamine methacrylamide (MABC for short);
(3) loading of corrosion inhibitor: dispersing the stimuli-responsive mesoporous silica and the corrosion inhibitor in tetrahydrofuran, fully adsorbing for more than 12 hours, centrifugally separating, cleaning and drying; the weight ratio of the stimulus responsive mesoporous silica to the corrosion inhibitor is 1: (0.3-1): 1;
(4) the stimulation responsive mesoporous silica loaded with the corrosion inhibitor is uniformly mixed with the resin condensate and then coated on the surface of the metal to form an anticorrosive coating.
The preparation method of the automatically repairable anticorrosive coating comprises the following steps:
(1) preparing mesoporous silica as a nano container;
(1a) the method comprises the following steps Dissolving a certain amount of dodecyl trimethyl ammonium bromide and sodium hydroxide in water to obtain an alkaline aqueous solution; slowly dripping tetraethyl oxysilane into the alkaline aqueous solution, and reacting for 4-6h at constant temperature under stirring; carrying out centrifugal separation, washing and drying to obtain mesoporous silica microsphere MSN;
the concentration of dodecyl trimethyl ammonium bromide in the alkaline aqueous solution is 2-6 g/L, the concentration of sodium hydroxide is 1-2 g/L, and the volume ratio of tetraethyl oxysilane to the aqueous solution is (1-5): 100, the reaction temperature is 70-90 ℃;
(1b) the method comprises the following steps Dispersing the mesoporous silica microsphere MSN in a toluene solution, dropwise adding a silane coupling agent-glycidyl ether propyl trimethoxy silane, carrying out reflux reaction for more than 12h, carrying out centrifugal separation, washing and drying to obtain an epoxy group modified mesoporous silica microsphere (MSN-epoxy);
the weight ratio of the mesoporous silica microspheres to the glycidyl ether propyl trimethoxy silane is (0.5-2): 1;
(1c) the method comprises the following steps Dispersing epoxy group modified mesoporous silica microspheres (MSN-epoxy) in a methanol/hydrochloric acid mixed solution (the concentration of hydrochloric acid in the solution is 1-3 mol/L), performing reflux reaction overnight, performing centrifugal separation, washing and drying to obtain hydroxyl group modified mesoporous silica microspheres (MSN-OH); the surfactant dodecyl trimethyl ammonium bromide is also removed while the epoxy group is converted into the hydroxyl group;
(2) preparing stimulus-responsive mesoporous silica, and endowing the stimulus-responsive mesoporous silica with stimulus responsiveness;
(2a) the method comprises the following steps Ultrasonically dispersing hydroxyl-modified mesoporous silica microspheres (MSN-OH) into dichloromethane, adding a carboxyl-containing chain transfer reagent, namely 4-cyanovaleric acid dithiobenzoate (CTP), a catalyst, namely 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride and 4-dimethylaminopyridine, stirring for reacting for 12 hours, centrifugally separating, washing and drying to obtain dithiobenzoate-modified mesoporous silica microspheres (MSN-RAFT);
the weight ratio of 4-cyano valeric acid dithiobenzoate (CTP) to mesoporous silica microspheres is (0.5-2.0): 1;
(2b) the method comprises the following steps Dispersing or dissolving a functional monomer N-tert-butylcarbonyl cystamine methacrylamide, dithiobenzoate-modified mesoporous silica microsphere MSN-RAFT and a thermal initiator in tetrahydrofuran, heating for polymerization reaction for more than 12 hours, centrifugally separating, washing and drying to obtain stimulus-responsive mesoporous silica MSN-PMABC;
the weight ratio of the functional monomer N-tert-butylcarbonyl cystamine methacrylamide to the dithiobenzoate modified mesoporous silica microsphere is (2-5): 1, the polymerization temperature is 50-80 ℃.
(3) Loading of corrosion inhibitor: dispersing the stimuli-responsive mesoporous silica and the corrosion inhibitor in tetrahydrofuran, fully adsorbing for more than 12 hours, centrifugally separating, cleaning and drying; the weight ratio of the stimulus responsive mesoporous silica to the corrosion inhibitor is 1: (0.3-1);
(4) the stimulation responsive mesoporous silica loaded with the corrosion inhibitor and a resin cured product (formed by curing a base resin, a curing agent and water) are uniformly mixed and then coated on the surface of metal to form an anticorrosive coating.
The preparation method of the resin condensate comprises the following steps: and uniformly mixing the base resin, the curing agent and water.
Example 1:
the preparation method of the automatically repairable anticorrosive coating comprises the following steps:
(1) preparing mesoporous silica as a nano container;
(1a) the method comprises the following steps Dissolving 10g of dodecyl trimethyl ammonium bromide and 5g of sodium hydroxide in 5L of water to obtain an alkaline aqueous solution; slowly dropping 50mL of tetraethyloxysilane into the alkaline aqueous solution, and reacting for 4 hours at a constant temperature of 70 ℃ while stirring; carrying out centrifugal separation, washing and drying to obtain mesoporous silica microsphere MSN;
(1b) the method comprises the following steps Dispersing the mesoporous silica microsphere MSN in a toluene solution, dropwise adding a silane coupling agent-glycidyl ether propyl trimethoxy silane, carrying out reflux reaction for 12h, carrying out centrifugal separation, washing and drying to obtain an epoxy group modified mesoporous silica microsphere (MSN-epoxy);
the weight ratio of the mesoporous silica microspheres to the glycidyl ether propyl trimethoxy silane is 0.5: 1;
(1c) the method comprises the following steps Dispersing epoxy group modified mesoporous silica microspheres (MSN-epoxy) in a methanol/hydrochloric acid mixed solution (the concentration of hydrochloric acid in the solution is 1 mol/L), performing reflux reaction overnight, performing centrifugal separation, washing and drying to obtain hydroxyl group modified mesoporous silica microspheres (MSN-OH); the surfactant dodecyl trimethyl ammonium bromide is also removed while the epoxy group is converted into the hydroxyl group;
(2) preparing stimulus-responsive mesoporous silica, and endowing the stimulus-responsive mesoporous silica with stimulus responsiveness;
(2a) the method comprises the following steps Ultrasonically dispersing hydroxyl-modified mesoporous silica microspheres (MSN-OH) into dichloromethane, adding a carboxyl-containing chain transfer reagent, namely 4-cyanovaleric acid dithiobenzoate (CTP), a catalyst, namely 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride and 4-dimethylaminopyridine, stirring for reacting for 12 hours, centrifugally separating, washing and drying to obtain dithiobenzoate-modified mesoporous silica microspheres (MSN-RAFT);
the weight ratio of 4-cyano valeric acid dithiobenzoate (CTP) to mesoporous silica microspheres is 0.5: 1; the weight ratio of the hydroxyl modified mesoporous silica microsphere to the 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride to the 4-dimethylaminopyridine is 8: 4: 0.3;
(2b) the method comprises the following steps Dispersing or dissolving a functional monomer N-tert-butylcarbonyl cystamine methacrylamide, dithiobenzoate-modified mesoporous silica microsphere MSN-RAFT and a thermal initiator V501 in tetrahydrofuran, heating for polymerization reaction for 12 hours, performing centrifugal separation, washing and drying to obtain stimulus-responsive mesoporous silica MSN-PMABC;
the weight ratio of the functional monomer N-tert-butylcarbonyl cystamine methacrylamide to the dithiobenzoate modified mesoporous silica microsphere is 2: 1, the polymerization temperature is 50 ℃, and the mass ratio of the thermal initiator V501 to the functional monomer N-tert-butylcarbonyl cystamine methacrylamide is 1: 210.
(3) loading of corrosion inhibitor: dispersing the stimulus-responsive mesoporous silica and a corrosion inhibitor benzotriazole in tetrahydrofuran, fully adsorbing for 12h, performing centrifugal separation, cleaning and drying; the weight ratio of the stimulus responsive mesoporous silica to the corrosion inhibitor benzotriazole is 1: 0.3;
(4) 0.5kg of the stimulus-responsive mesoporous silica loaded with the corrosion inhibitor and 99.5kg of a resin cured product (formed by curing a base resin and a curing agent) are uniformly mixed and then coated on the surface of the metal to form an anticorrosive coating. The resin condensate is an epoxy resin condensate formed by curing epoxy resin and an epoxy curing agent, the epoxy resin is bisphenol A type epoxy resin, and the epoxy curing agent is polyetheramine D230 and n-decylamine.
Example 2:
the preparation method of the automatically repairable anticorrosive coating comprises the following steps:
(1) preparing mesoporous silica as a nano container;
(1a) the method comprises the following steps Dissolving 15g of dodecyl trimethyl ammonium bromide and 6g of sodium hydroxide in 5L of water to obtain an alkaline aqueous solution; slowly dropping 100mL of tetraethyloxysilane into the alkaline aqueous solution, and reacting for 4.5h at a constant temperature of 75 ℃ while stirring; carrying out centrifugal separation, washing and drying to obtain mesoporous silica microsphere MSN;
(1b) the method comprises the following steps Dispersing the mesoporous silica microsphere MSN in a toluene solution, dropwise adding a silane coupling agent-glycidyl ether propyl trimethoxy silane, carrying out reflux reaction for 13h, carrying out centrifugal separation, washing and drying to obtain an epoxy group modified mesoporous silica microsphere (MSN-epoxy);
the weight ratio of the mesoporous silica microspheres to the glycidyl ether propyl trimethoxy silane is 1.0: 1;
(1c) the method comprises the following steps Dispersing epoxy group modified mesoporous silica microspheres (MSN-epoxy) in a methanol/hydrochloric acid mixed solution (the concentration of hydrochloric acid in the solution is 1.5 mol/L), performing reflux reaction overnight, performing centrifugal separation, washing and drying to obtain hydroxyl group modified mesoporous silica microspheres (MSN-OH); the surfactant dodecyl trimethyl ammonium bromide is also removed while the epoxy group is converted into the hydroxyl group;
(2) preparing stimulus-responsive mesoporous silica, and endowing the stimulus-responsive mesoporous silica with stimulus responsiveness;
(2a) the method comprises the following steps Ultrasonically dispersing hydroxyl-modified mesoporous silica microspheres (MSN-OH) into dichloromethane, adding a carboxyl-containing chain transfer reagent, namely 4-cyanovaleric acid dithiobenzoate (CTP), a catalyst, namely 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride and 4-dimethylaminopyridine, stirring for reacting for 12 hours, centrifugally separating, washing and drying to obtain dithiobenzoate-modified mesoporous silica microspheres (MSN-RAFT);
the weight ratio of 4-cyano valeric acid dithiobenzoate (CTP) to mesoporous silica microspheres is 1.0: 1; the weight ratio of the hydroxyl modified mesoporous silica microsphere to the 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride to the 4-dimethylaminopyridine is 8: 4: 0.3;
(2b) the method comprises the following steps Dispersing or dissolving a functional monomer N-tert-butylcarbonyl cystamine methacrylamide, dithiobenzoate-modified mesoporous silica microsphere MSN-RAFT and a thermal initiator V501 in tetrahydrofuran, heating for polymerization reaction for 13h, performing centrifugal separation, washing and drying to obtain stimulus-responsive mesoporous silica MSN-PMABC;
the weight ratio of the functional monomer N-tert-butylcarbonyl cystamine methacrylamide to the dithiobenzoate modified mesoporous silica microsphere is 3: 1, the polymerization temperature is 60 ℃, and the mass ratio of the thermal initiator V501 to the functional monomer N-tert-butylcarbonyl cystamine methacrylamide is 1: 210.
(3) loading of corrosion inhibitor: dispersing the stimulus-responsive mesoporous silica and the methyl benzotriazole serving as a corrosion inhibitor in tetrahydrofuran, fully adsorbing for 13 hours, performing centrifugal separation, cleaning and drying; the weight ratio of the stimulus responsive mesoporous silica to the corrosion inhibitor methylbenzotriazole is 1: 0.5;
(4) 1.0kg of the stimulus-responsive mesoporous silica loaded with the corrosion inhibitor and 99.0kg of a resin cured product (formed by curing a base resin and a curing agent) are uniformly mixed and then coated on the surface of metal to form an anticorrosive coating. The resin cured product is a polyurethane cured product formed by curing a hydroxyl-containing resin and an isocyanate curing agent.
Example 3:
the preparation method of the automatically repairable anticorrosive coating comprises the following steps:
(1) preparing mesoporous silica as a nano container;
(1a) the method comprises the following steps Dissolving 20g of dodecyl trimethyl ammonium bromide and 7g of sodium hydroxide in 5L of water to obtain an alkaline aqueous solution; slowly dropping 150mL of tetraethyloxysilane into the alkaline aqueous solution, and reacting for 5 hours at a constant temperature of 80 ℃ while stirring; carrying out centrifugal separation, washing and drying to obtain mesoporous silica microsphere MSN;
(1b) the method comprises the following steps Dispersing mesoporous silica microspheres MSN into a toluene solution, dropwise adding a silane coupling agent-glycidyl ether propyl trimethoxy silane, carrying out reflux reaction for 14h, carrying out centrifugal separation, washing and drying to obtain epoxy group modified mesoporous silica microspheres (MSN-epoxy);
the weight ratio of the mesoporous silica microspheres to the glycidyl ether propyl trimethoxy silane is 1.2: 1;
(1c) the method comprises the following steps Dispersing epoxy group modified mesoporous silica microspheres (MSN-epoxy) in a methanol/hydrochloric acid mixed solution (the concentration of hydrochloric acid in the solution is 2 mol/L), performing reflux reaction overnight, performing centrifugal separation, washing and drying to obtain hydroxyl group modified mesoporous silica microspheres (MSN-OH); the surfactant dodecyl trimethyl ammonium bromide is also removed while the epoxy group is converted into the hydroxyl group;
(2) preparing stimulus-responsive mesoporous silica, and endowing the stimulus-responsive mesoporous silica with stimulus responsiveness;
(2a) the method comprises the following steps Ultrasonically dispersing hydroxyl-modified mesoporous silica microspheres (MSN-OH) into dichloromethane, adding a carboxyl-containing chain transfer reagent, namely 4-cyanovaleric acid dithiobenzoate (CTP), a catalyst, namely 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride and 4-dimethylaminopyridine, stirring for reacting for 12 hours, centrifugally separating, washing and drying to obtain dithiobenzoate-modified mesoporous silica microspheres (MSN-RAFT);
the weight ratio of 4-cyano valeric acid dithiobenzoate (CTP) to mesoporous silica microspheres is 1.2: 1; the weight ratio of the hydroxyl modified mesoporous silica microsphere to the 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride to the 4-dimethylaminopyridine is 8: 4: 0.3;
(2b) the method comprises the following steps Dispersing or dissolving a functional monomer N-tert-butylcarbonyl cystamine methacrylamide, dithiobenzoate-modified mesoporous silica microsphere MSN-RAFT and a thermal initiator V501 in tetrahydrofuran, heating for polymerization reaction for 14h, performing centrifugal separation, washing and drying to obtain stimulus-responsive mesoporous silica MSN-PMABC;
the weight ratio of the functional monomer N-tert-butylcarbonyl cystamine methacrylamide to the dithiobenzoate modified mesoporous silica microsphere is 4: 1, the polymerization temperature is 65 ℃, the mass ratio of the thermal initiator V501 to the functional monomer N-tert-butylcarbonyl cystamine methacrylamide is 1: 210.
(3) loading of corrosion inhibitor: dispersing the stimuli-responsive mesoporous silica and the corrosion inhibitor mercaptobenzothiazole in tetrahydrofuran, fully adsorbing for 14 hours, centrifugally separating, cleaning and drying; the weight ratio of the stimulus-responsive mesoporous silica to the corrosion inhibitor mercaptobenzothiazole is 1: 0.6;
(4) 2.0kg of the corrosion inhibitor-loaded stimuli-responsive mesoporous silica and 98.0kg of a resin cured product (formed by curing a base resin and a curing agent) are uniformly mixed and then coated on the surface of metal to form an anticorrosive coating. The resin condensate is an epoxy resin condensate formed by curing epoxy resin and an epoxy curing agent, the epoxy resin is bisphenol A type epoxy resin, and the epoxy curing agent is polyetheramine D230 and n-decylamine.
Example 4:
the preparation method of the automatically repairable anticorrosive coating comprises the following steps:
(1) preparing mesoporous silica as a nano container;
(1a) the method comprises the following steps Dissolving 25g of dodecyl trimethyl ammonium bromide and 8g of sodium hydroxide in 5L of water to obtain an alkaline aqueous solution; slowly dropping 200mL of tetraethyloxysilane into the alkaline aqueous solution, and reacting for 5.5 hours at a constant temperature of 85 ℃ while stirring; carrying out centrifugal separation, washing and drying to obtain mesoporous silica microsphere MSN;
(1b) the method comprises the following steps Dispersing the mesoporous silica microsphere MSN in a toluene solution, dropwise adding a silane coupling agent-glycidyl ether propyl trimethoxy silane, carrying out reflux reaction for 15h, carrying out centrifugal separation, washing and drying to obtain an epoxy group modified mesoporous silica microsphere (MSN-epoxy);
the weight ratio of the mesoporous silica microspheres to the glycidyl ether propyl trimethoxy silane is 1.6: 1;
(1c) the method comprises the following steps Dispersing epoxy group modified mesoporous silica microspheres (MSN-epoxy) in a methanol/hydrochloric acid mixed solution (the concentration of hydrochloric acid in the solution is 2.5 mol/L), performing reflux reaction overnight, performing centrifugal separation, washing and drying to obtain hydroxyl group modified mesoporous silica microspheres (MSN-OH); the surfactant dodecyl trimethyl ammonium bromide is also removed while the epoxy group is converted into the hydroxyl group;
(2) preparing stimulus-responsive mesoporous silica, and endowing the stimulus-responsive mesoporous silica with stimulus responsiveness;
(2a) the method comprises the following steps Ultrasonically dispersing hydroxyl-modified mesoporous silica microspheres (MSN-OH) into dichloromethane, adding a carboxyl-containing chain transfer reagent, namely 4-cyanovaleric acid dithiobenzoate (CTP), a catalyst, namely 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride and 4-dimethylaminopyridine, stirring for reacting for 12 hours, centrifugally separating, washing and drying to obtain dithiobenzoate-modified mesoporous silica microspheres (MSN-RAFT);
the weight ratio of 4-cyano valeric acid dithiobenzoate (CTP) to mesoporous silica microspheres is 1.6: 1; the weight ratio of the hydroxyl modified mesoporous silica microsphere to the 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride to the 4-dimethylaminopyridine is 8: 4: 0.3;
(2b) the method comprises the following steps Dispersing or dissolving a functional monomer N-tert-butylcarbonyl cystamine methacrylamide, dithiobenzoate-modified mesoporous silica microsphere MSN-RAFT and a thermal initiator V501 in tetrahydrofuran, heating for polymerization reaction for 14h, performing centrifugal separation, washing and drying to obtain stimulus-responsive mesoporous silica MSN-PMABC;
the weight ratio of the functional monomer N-tert-butylcarbonyl cystamine methacrylamide to the dithiobenzoate modified mesoporous silica microsphere is 4.5: 1, the polymerization temperature is 70 ℃, and the mass ratio of the thermal initiator V501 to the functional monomer N-tert-butylcarbonyl cystamine methacrylamide is 1: 210.
(3) loading of corrosion inhibitor: dispersing the stimulus-responsive mesoporous silica and the corrosion inhibitor 8-hydroxyquinoline in tetrahydrofuran, fully adsorbing for 14 hours, centrifugally separating, cleaning and drying; the weight ratio of the stimulus responsive mesoporous silica to the corrosion inhibitor 8-hydroxyquinoline is 1: 0.8;
(4) 3.0kg of the stimulus-responsive mesoporous silica loaded with the corrosion inhibitor and 97.0kg of a resin cured product (formed by curing a base resin and a curing agent) are uniformly mixed, and then the mixture is coated on the surface of metal to form an anticorrosive coating. The resin cured product is a polyurethane cured product formed by curing a hydroxyl-containing resin and an isocyanate curing agent.
Example 5:
the preparation method of the automatically repairable anticorrosive coating comprises the following steps:
(1) preparing mesoporous silica as a nano container;
(1a) the method comprises the following steps Dissolving 30g of dodecyl trimethyl ammonium bromide and 10g of sodium hydroxide in 5L of water to obtain an alkaline aqueous solution; slowly dropping 250mL of tetraethyloxysilane into the alkaline aqueous solution, and reacting for 6 hours at a constant temperature under stirring, wherein the reaction temperature is 90 ℃; carrying out centrifugal separation, washing and drying to obtain mesoporous silica microsphere MSN;
(1b) the method comprises the following steps Dispersing mesoporous silica microspheres MSN into a toluene solution, dropwise adding a silane coupling agent-glycidyl ether propyl trimethoxy silane, carrying out reflux reaction for 16h, carrying out centrifugal separation, washing and drying to obtain epoxy group modified mesoporous silica microspheres (MSN-epoxy);
the weight ratio of the mesoporous silica microspheres to the glycidyl ether propyl trimethoxy silane is 2: 1;
(1c) the method comprises the following steps Dispersing epoxy group modified mesoporous silica microspheres (MSN-epoxy) in a methanol/hydrochloric acid mixed solution (the concentration of hydrochloric acid in the solution is 3 mol/L), performing reflux reaction overnight, performing centrifugal separation, washing and drying to obtain hydroxyl group modified mesoporous silica microspheres (MSN-OH); the surfactant dodecyl trimethyl ammonium bromide is also removed while the epoxy group is converted into the hydroxyl group;
(2) preparing stimulus-responsive mesoporous silica, and endowing the stimulus-responsive mesoporous silica with stimulus responsiveness;
(2a) the method comprises the following steps Ultrasonically dispersing hydroxyl-modified mesoporous silica microspheres (MSN-OH) into dichloromethane, adding a carboxyl-containing chain transfer reagent, namely 4-cyanovaleric acid dithiobenzoate (CTP), a catalyst, namely 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride and 4-dimethylaminopyridine, stirring for reacting for 12 hours, centrifugally separating, washing and drying to obtain dithiobenzoate-modified mesoporous silica microspheres (MSN-RAFT);
the weight ratio of 4-cyano valeric acid dithiobenzoate (CTP) to mesoporous silica microspheres is 2: 1; the weight ratio of the hydroxyl modified mesoporous silica microsphere to the 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride to the 4-dimethylaminopyridine is 8: 4: 0.3;
(2b) the method comprises the following steps Dispersing or dissolving a functional monomer N-tert-butylcarbonyl cystamine methacrylamide, dithiobenzoate-modified mesoporous silica microsphere MSN-RAFT and a thermal initiator V501 in tetrahydrofuran, heating for polymerization reaction for 15h, performing centrifugal separation, washing and drying to obtain stimulus-responsive mesoporous silica MSN-PMABC;
the weight ratio of the functional monomer N-tert-butylcarbonyl cystamine methacrylamide to the dithiobenzoate modified mesoporous silica microsphere is 5: 1, the polymerization temperature is 80 ℃, and the mass ratio of the thermal initiator V501 to the functional monomer N-tert-butylcarbonyl cystamine methacrylamide is 1: 210.
(3) loading of corrosion inhibitor: dispersing the stimulus-responsive mesoporous silica, the corrosion inhibitor benzotriazole and the methylbenzotriazole in tetrahydrofuran, fully adsorbing for 15h, centrifugally separating, cleaning and drying; the weight ratio of the stimulus responsive mesoporous silica to the benzotriazole to the methyl benzotriazole is 1: 0.5: 0.5;
(4) 5.0kg of the stimulus-responsive mesoporous silica loaded with the corrosion inhibitor and 95.0kg of a resin cured product (formed by curing a base resin and a curing agent) are uniformly mixed and then coated on the surface of the metal to form an anticorrosive coating. The resin condensate is an epoxy resin condensate formed by curing epoxy resin and an epoxy curing agent, the epoxy resin is bisphenol A type epoxy resin, and the epoxy curing agent is polyetheramine D230 and n-decylamine.
Example 6:
(1) preparing mesoporous silicon dioxide (MSN-OH) as a nano-container
(1a) Dodecyl trimethyl ammonium bromide (20.0 g) and sodium hydroxide (6.5 g) were dissolved in 5L of water, stirred well and heated to 80 ℃. 100mL of tetraethyloxysilane was slowly added dropwise to the above solution, and the reaction was stirred at 80 ℃ for 4 hours. And (4) carrying out centrifugal separation, washing and drying to obtain the mesoporous silica microsphere MSN.
(1b) Dispersing the prepared mesoporous silica microsphere MSN (8.0 g) in 0.8L toluene solution, dripping a silane coupling agent-glycidyl ether propyl trimethoxy silane (8.0 g) under the protection of argon, carrying out reflux reaction overnight, carrying out centrifugal separation, washing and drying to obtain the epoxy group modified mesoporous silica microsphere (MSN-epoxy).
(1c) Epoxy group modified mesoporous silica microspheres (MSN-epoxy) are dispersed in 3L of methanol/hydrochloric acid mixed solvent (the concentration of hydrochloric acid is 1.6 mol/L), and reflux reaction is carried out overnight. The surfactant dodecyltrimethylammonium bromide is also removed at the same time that the epoxy group is converted to a hydroxyl group. And (4) carrying out centrifugal separation, washing and drying to obtain the hydroxyl modified mesoporous silica microsphere (MSN-OH).
(2) Preparation of stimulus-responsive mesoporous silica MSN-PMABC
(2a) The method comprises the following steps Ultrasonically dispersing 8.0g of hydroxyl-modified mesoporous silica microspheres (MSN-OH) into 0.5L of dichloromethane, adding 8.0g of 4-cyanovaleric acid dithiobenzoate (CTP), adding 4.0g of catalyst 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride (esterification catalyst) and 0.3g of 4-dimethylaminopyridine (acylation catalyst), stirring for 12 hours, carrying out centrifugal separation, washing and drying to obtain pink product dithiobenzoate-modified mesoporous silica microspheres (MSN-RAFT).
(2b) Monomer MABC (21.0 g), dithiobenzoate modified mesoporous silica microsphere MSN-RAFT (7.0 g) and initiator V501(100 mg) are dispersed/dissolved in THF (500 mL), and are polymerized for 12h at 60 ℃, and after the reaction is stopped, the monomer is centrifugally separated, washed, dried and dried to obtain the light pink stimulation responsive mesoporous silica MSN-PMABC.
Thermogravimetric analysis (TGA): the weight loss of the sample was measured on a TGA-7 thermogravimetric analyzer from Perkin-Elmer company at a temperature range of 100 ℃ and 650 ℃, a temperature rise rate of 15 ℃/min and a nitrogen flow of 20 mL/min. As shown in Table 1, the test results show that the weight loss rate of MSN-PMABC is obviously higher than that of MSN-OH at 650 ℃, which indicates that the polymer chain segment PMABC is successfully polymerized on the surface of MSN.
(3) Loading of corrosion inhibitors
Dispersing and dissolving 10g of stimulus responsive mesoporous silica MSN-PMABC and 3g of corrosion inhibitor (benzotriazole) in 1L of tetrahydrofuran, fully adsorbing for more than 12h, centrifugally separating, cleaning and drying to obtain the stimulus responsive mesoporous silica MSN-PMABC loaded with the corrosion inhibitor.
(4) Stimulus responsive release
In order to research the influence of acid stimulation or reducing agent stimulation on the release rate of the corrosion inhibitor molecules, 10mg of stimulation responsive mesoporous silica encapsulated with the corrosion inhibitor molecules is placed in a dialysis bag, the dialysis bag is placed in solutions with different pH values or solutions added with reducing agents, and the content of the dialyzed corrosion inhibitor is measured after a certain time, so that the cumulative release condition of the corrosion inhibitor under different conditions can be obtained.
FIG. 2 shows the release of the corrosion inhibitor using MSN-PMABC as the corrosion inhibitor carrier. Under the stimulation of a reducing agent, the corrosion inhibitor is quickly released, 58% can be released in 4 hours, and the release of the control is only less than 10%. Under the stimulation of acid, the corrosion inhibitor can be quickly released, for example, the corrosion inhibitor can be released 50% at pH 5 and 4h, the release is quicker at pH 2, and the release is less than 10% at pH 7.4 and 4 h.
The principle that the corrosion inhibitor can be quickly released from the stimulus-responsive mesoporous silica under the stimulus of a reducing agent and an acid is as follows: the shell polymer chain is sensitive to a reducing agent and acid, and N-tert-butylcarbonyl can be rapidly hydrolyzed and separated under acid stimulation; and under the stimulation of a reducing agent, the disulfide bonds can be broken. The above changes all cause the shell polymer chain to be changed from hydrophobic polymer to hydrophilic polymer, so the chain segment extends in the water environment, and the orifice of the mesoporous silica is exposed, and the loaded corrosion inhibitor is released rapidly (figure 3).
Example 7:
(1) mesoporous silica (MSN-OH) was prepared as a nanocontainer, see example 6.
(2) A stimuli-responsive mesoporous silica MSN-PMABC was prepared as described in example 6.
(3) The loading of the corrosion inhibitor is specifically shown in example 6, and the stimulus-responsive mesoporous silica MSN-PMABC loaded with the corrosion inhibitor is prepared.
(4) Preparation of the coating
(4a) 40 g of the aqueous polyurethane resin and 2 g of the isocyanate curing agent (Bayhydur 3100) were weighed, 5g of water was added, and the mixture was mixed well.
(4b) And (3) weighing 1.0 g of the corrosion inhibitor-loaded stimuli-responsive mesoporous silica MSN-PBEMAGG obtained in the step (3), adding the weighed materials into the mixture, and fully and uniformly stirring the mixture.
(4c) And (3) immersing a carbon steel sheet (40 × 20 × 2 mm) into the mixture to an immersion depth of 3cm, after immersing for 1min, pulling, and drying the pulled carbon steel sheet at 120 ℃ for 2h to form a self-repairing anticorrosive coating on the surface of the carbon steel.
Example 8:
(1) mesoporous silica (MSN-OH) was prepared as a nanocontainer, see example 6.
(2) A stimuli-responsive mesoporous silica MSN-PMABC was prepared as described in example 6.
(3) The loading of the corrosion inhibitor is specifically shown in example 6, and the stimulus-responsive mesoporous silica MSN-PMABC loaded with the corrosion inhibitor is prepared.
(4) Preparation of the coating
(4a) 25g of bisphenol A epoxy resin and 5g of epoxy curing agent (polyetheramine D230) were weighed, 5g of water was added, and the mixture was mixed well.
(4b) And (3) weighing 0.5 g of the corrosion inhibitor-loaded stimuli-responsive mesoporous silica MSN-PMABC obtained in the step (3), adding the weighed materials into the mixture, and fully and uniformly stirring the mixture.
(4c) And (3) immersing a carbon steel sheet (40 × 20 × 2 mm) into the mixture to an immersion depth of 3cm, after immersing for 1min, pulling, and drying the pulled carbon steel sheet at 120 ℃ for 2h to form a self-repairing anticorrosive coating on the surface of the carbon steel.
As shown in fig. 4, the self-repairable anticorrosive coating 1 is formed by dispersing a stimulus-responsive mesoporous silica 2 loaded with a corrosion inhibitor in a cured resin material 3; the automatically repaired anti-corrosion coating 1 is coated on the metal substrate 4 to play a role in anti-corrosion of the metal substrate.
When the resin condensate is not locally damaged, the corrosion inhibitor molecule existsIs stored in the mesoporous silica pore canal. When the coating is damaged and cracked due to the invasion of various external conditions in the service process, external acid or reducing agent is diffused and is contacted with the stimulus responsive mesoporous silicon dioxide which is dispersed in the coating and loaded with the slow release agent; stimulated by external acid or reducing agent to stimulate responsive mesoporous silicon dioxide shell polymer chain segmentNThe hydrolysis of tert-butyl carbonyl group leaves (under the stimulation of acid) or the breakage of disulfide bonds (under the stimulation of reducing agent) causes the hydrophobic-hydrophilic conversion of shell layer macromolecules (see figure 3), thereby exposing the pore channels of the mesoporous silica, quickly releasing the loaded corrosion inhibitor, forming a protective passivation film at the defect position, realizing self-repairing and effectively inhibiting corrosion.
Evaluation of corrosion resistance effect of self-repairing anticorrosive coating
Respectively selecting a coated self-repairing anticorrosive coating (A, example 8) and a common polymer anticorrosive coating (B, stimulus-responsive mesoporous silica loaded with a corrosion inhibitor is not added, and the rest of the preparation process is the same as that of example 8), and soaking the coatings in a solution of 1mol/L sodium chloride and pH = 3.
The coatings were tested for corrosion protection using electrochemical impedance spectroscopy and the results are shown in fig. 6-7. At the time of immersion (0 d), the resistance value of A, B was large, and the metal had not corroded yet. After soaking for 7 days, the impedance A is only reduced slightly, and the corrosion is not obvious; and the impedance platform of B is obviously reduced, and the corrosion degree of B is obviously higher than that of A, which shows that the anticorrosion effect of A is better than that of B. After soaking for 1 month (30 d), the impedance of A is higher than that of B by about 2 orders of magnitude, which shows that the anticorrosion effect of A is obviously better than that of B.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the overall concept of the present invention, and these should also be considered as the protection scope of the present invention.
Claims (8)
1. An automatically repairable anticorrosive coating, characterized in that: comprises the following parts
(1) 0.5-5 parts by weight of corrosion inhibitor-loaded stimuli-responsive mesoporous silica
(2) 95-99.5 parts by weight of cured resin
The corrosion inhibitor-loaded stimuli-responsive mesoporous silica consists of a corrosion inhibitor and stimuli-responsive mesoporous silica, wherein the corrosion inhibitor is positioned in a pore passage structure of the stimuli-responsive mesoporous silica, and the loading amount of the corrosion inhibitor is 5-10 wt%;
the stimulus-responsive mesoporous silica has a core-shell structure, the core is mesoporous silica, the shell layer is a macromolecule with responsiveness to a reducing agent and acid, and a side chain in the macromolecule contains N-tert-butylcarbonyl and a disulfide bond.
2. The self-healing corrosion protective coating according to claim 1, wherein: the polymer is poly (N-tert-butylcarbonyl cystamine methacrylamide).
3. The automatically repairable corrosion protective coating according to claim 1 or 2, wherein: the resin cured product is an epoxy resin cured product formed by curing epoxy resin, an epoxy curing agent and water.
4. The automatically repairable corrosion protective coating according to claim 1 or 2, wherein: the resin cured product is a polyurethane cured product formed by curing hydroxyl-containing resin, an isocyanate curing agent and water.
5. The automatically repairable corrosion protective coating according to claim 1 or 2, wherein: the corrosion inhibitor is at least one of benzotriazole, methylbenzotriazole, mercaptobenzothiazole and 8-hydroxyquinoline.
6. The self-healing corrosion protective coating according to claim 3, wherein: the epoxy resin is bisphenol A epoxy resin, and the epoxy curing agent is polyether amine D230 and n-decylamine.
7. A process for the preparation of an automatically repairable anti-corrosion coating according to any one of claims 1 to 6, characterized in that: the method comprises the following steps:
(1) preparing mesoporous silica as a nano container;
(1a) in an alkaline aqueous solution, dodecyl trimethyl ammonium bromide is used as a surfactant, tetraethyl oxysilane is used as a silicon source, and a sol-gel method is adopted to prepare mesoporous silica microspheres;
(1b) in an organic solvent, glycidyl ether propyl trimethoxy silane is used as a silane coupling agent to introduce epoxy groups on the surface of the mesoporous silica microsphere;
(1c) then in an acidic alcohol solution, the epoxy groups are subjected to ring opening and converted into hydroxyl groups, and meanwhile, the surfactant in the pore structure is also removed, so that the hydroxyl-modified mesoporous silica microspheres are obtained;
(2) preparing stimulus-responsive mesoporous silica, and endowing the stimulus-responsive mesoporous silica with stimulus responsiveness;
(2a) carrying out esterification reaction on the mesoporous silica microsphere modified by hydroxyl and a chain transfer reagent containing carboxyl, and introducing dithiobenzoate groups on the surface of the mesoporous silica to obtain the dithiobenzoate group modified mesoporous silica microsphere;
(2b) taking the mesoporous silica microsphere modified by dithiobenzoate as a chain transfer agent, performing reversible addition-fragmentation chain transfer polymerization of a functional monomer on the surface of the mesoporous silica, and grafting a stimulus-responsive polymer chain segment to the surface of the mesoporous silica to obtain the stimulus-responsive mesoporous silica; the functional monomer is N-tert-butylcarbonyl cystamine methacrylamide;
(3) loading of corrosion inhibitor: dispersing the stimuli-responsive mesoporous silica and the corrosion inhibitor in tetrahydrofuran, fully adsorbing for more than 12 hours, centrifugally separating, cleaning and drying; the weight ratio of the stimulus responsive mesoporous silica to the corrosion inhibitor is 1: (0.3-1);
(4) the stimulation responsive mesoporous silica loaded with the corrosion inhibitor is uniformly mixed with the resin condensate and then coated on the surface of the metal to form an anticorrosive coating.
8. The method for preparing an automatically repairable corrosion-resistant coating according to claim 7, wherein: the method comprises the following steps:
(1) preparing mesoporous silica as a nano container;
(1a) the method comprises the following steps Dissolving a certain amount of dodecyl trimethyl ammonium bromide and sodium hydroxide in water to obtain an alkaline aqueous solution; dripping tetraethyl oxysilane into the alkaline aqueous solution, and reacting for 4-6h at constant temperature under stirring; carrying out centrifugal separation, washing and drying to obtain mesoporous silica microspheres;
the concentration of dodecyl trimethyl ammonium bromide in the alkaline aqueous solution is 2-6 g/L, the concentration of sodium hydroxide is 1-2 g/L, and the volume ratio of tetraethyl oxysilane to the aqueous solution is (1-5): 100, the reaction temperature is 70-90 ℃;
(1b) the method comprises the following steps Dispersing mesoporous silica microspheres into a toluene solution, dropwise adding a silane coupling agent-glycidyl ether propyl trimethoxy silane, carrying out reflux reaction for more than 12 hours, carrying out centrifugal separation, washing and drying to obtain epoxy group modified mesoporous silica microspheres;
the weight ratio of the mesoporous silica microspheres to the glycidyl ether propyl trimethoxy silane is (0.5-2): 1;
(1c) the method comprises the following steps Dispersing the epoxy group modified mesoporous silica microspheres in a methanol/hydrochloric acid mixed solution, carrying out reflux reaction overnight, carrying out centrifugal separation, washing and drying to obtain hydroxyl group modified mesoporous silica microspheres; the surfactant dodecyl trimethyl ammonium bromide is also removed while the epoxy group is converted into the hydroxyl group;
(2) preparing stimulus-responsive mesoporous silica, and endowing the stimulus-responsive mesoporous silica with stimulus responsiveness;
(2a) the method comprises the following steps Ultrasonically dispersing hydroxyl-modified mesoporous silica microspheres into dichloromethane, adding a carboxyl-containing chain transfer reagent, namely 4-cyanovaleric acid dithiobenzoate, a catalyst, namely 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride and 4-dimethylaminopyridine, stirring for reacting for 12 hours, then carrying out centrifugal separation, washing and drying to obtain dithiobenzoate-modified mesoporous silica microspheres;
the weight ratio of 4-cyano valeric acid dithiobenzoate to mesoporous silica microspheres is (0.5-2.0): 1;
(2b) the method comprises the following steps Dispersing or dissolving a functional monomer N-tert-butylcarbonyl cystamine methacrylamide, dithiobenzoate modified mesoporous silica microspheres and a thermal initiator in tetrahydrofuran, heating for polymerization reaction for more than 12 hours, centrifugally separating, washing and drying to obtain stimulus-responsive mesoporous silica;
the weight ratio of the functional monomer N-tert-butylcarbonyl cystamine methacrylamide to the dithiobenzoate modified mesoporous silica microsphere is (2-5): 1, the polymerization temperature is 50-80 ℃;
(3) loading of corrosion inhibitor: dispersing the stimuli-responsive mesoporous silica and the corrosion inhibitor in tetrahydrofuran, fully adsorbing for more than 12 hours, centrifugally separating, cleaning and drying; the weight ratio of the stimulus responsive mesoporous silica to the corrosion inhibitor is 1: (0.3-1);
(4) the stimulation responsive mesoporous silica loaded with the corrosion inhibitor is uniformly mixed with the resin condensate and then coated on the surface of the metal to form an anticorrosive coating.
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| CN113756106A (en) * | 2021-09-28 | 2021-12-07 | 江苏厚生新能源科技有限公司 | Waterproof and corrosion-resistant polypropylene fabric and preparation process thereof |
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