A method for preparing cuprous oxide and multi-branched polymer composite microcapsules

Abstract

This invention discloses a method for preparing cuprous oxide and multibranched polymer composite microcapsules. First, a prepolymer containing hydrophilic copper-complexing dimethylamino groups with epoxy end groups is synthesized using free radical living polymerization. Then, this prepolymer is condensed with polyamine molecules to prepare a multibranched block polymer, which is used as an additive in marine antifouling coatings. This additive polymer is blended with cuprous oxide nanoparticles, and based on the charge transfer effect between tertiary amines and copper, a composite microcapsule structure is formed, achieving encapsulation of copper antifouling agents. The advantages include effective control of copper antifouling agent release, while its multibranched structure increases the interaction force of the coating matrix resin, prolongs its residence time at the coating interface, and enhances the antifouling effect of the coating.

Description

Technical Field

[0001] This invention belongs to the field of materials science, specifically relating to a method for preparing a composite microcapsule of cuprous oxide and multibranched polymer. Background Technology

[0002] Marine antifouling coatings are the most economical and effective method to suppress marine biofouling on underwater parts of marine vessels and engineering projects, with copper-based self-polishing coatings accounting for over 90% of the market share. However, existing copper-based antifouling coatings often experience excessive copper ion release in the early stages of service, followed by insufficient release in the later stages, resulting in unstable antifouling performance. Therefore, to achieve effective antifouling, coating manufacturers often add excessive amounts of copper antifouling agents to marine coatings to maintain the rate of copper ion release in the later stages of coating service. In recent years, it has been found that excessive copper ion release has led to copper ion pollution in marine products. Since copper-based coatings are currently irreplaceable, effectively controlling the uniform release of copper ions is the best way to reduce copper ion pollution. In recent years, researchers have published a tertiary amine copper ion complex and its application in copper ion slow-release antifouling coatings (Journal of Chemical Research in Chinese Universities, 2018, 39, 1602-1610). Its characteristic is that it uses a random copolymer of polyacrylic acid resin containing a tertiary amine structure and cuprous oxide as the main components of marine coatings. Comparative studies show that this coating can effectively slow down copper ion release while achieving good antifouling performance. However, because the tertiary amines in this resin are randomly distributed structural units, most of the tertiary amine structures are difficult to effectively coat the surface of cuprous oxide. Its sustained-release effect on copper ions mainly manifests in a single mode where cuprous oxide forms ions in seawater and complexes with them. Therefore, the regulation of copper ion release needs further improvement. To further enhance the coating effect on inorganic cuprous oxide, the researchers used benzyl chloride as an initiator to prepare an amphiphilic polymer containing tertiary amines. The ordered tertiary amine structures in the above amphiphilic polymer can encapsulate cuprous oxide, increasing the compatibility between inorganic cuprous oxide and the organic polymer matrix, and further improving the regulated release of copper ions (Progress in organic coatings, 2022, 170, 107003). However, when it plays a role in regulating copper ions at the interface of coating renewal, it is easily washed away by seawater. This is mainly because the hydrophobic part in its one-dimensional linear structure has a small contact area with the coating matrix polymer, making it difficult to form a spatial three-dimensional entanglement effect of mutual transmission network, which makes it easy to be washed away at the coating interface.

[0003] To address the issue of linear amphiphilic polymers being easily washed away in seawater, this invention discloses a method for preparing cuprous oxide and multibranched polymer composite microcapsules. The method is characterized by the first use of epoxy halopropane as an atom transfer radical initiator to synthesize a diblock complexing prepolymer with epoxy end groups and containing tertiary amines. Further, a condensation reaction is carried out between the epoxy end groups and a polyamine compound containing active NH to generate a multibranched amphiphilic complexing polymer. Compared to linear polymers, this multibranched diblock polymer possesses a three-dimensional spatial structure, forming a complex entangled spatial structure with the coating matrix polymer, greatly increasing the interaction forces between them. This reduces the likelihood of the coating being washed away by seawater at the coating interface, contributing to its stable and sustained release of copper ions. Summary of the Invention

[0004] The purpose of this invention is to overcome the problem of traditional copper-based self-polishing antifouling coatings, which require excessive use of copper antifouling agents due to severe leaching in order to achieve antifouling effects. This invention provides a method for preparing cuprous oxide and multi-branched polymer composite microcapsules, aiming to regulate copper ion release efficiency, reduce ineffective copper ion loss, improve copper ion utilization, and achieve the same antifouling effect. This invention creatively designs and prepares multi-branched amphiphilic tertiary amine functional polymers, forming polymer composite microcapsules with cuprous oxide. Furthermore, the required raw materials are low-cost, the preparation process is simple, requires no complex equipment, is suitable for industrialization, and is conducive to widespread application.

[0005] To achieve the above-mentioned objectives, the present invention employs the technical solution described below, and the method is as follows:

[0006] A method for preparing cuprous oxide and multibranched polymer composite microcapsules, the preparation process includes the following two steps:

[0007] Step 1, the reaction for preparing the multibranched polymer is as follows: Equation 1:

[0008]

[0009] The preparation process of the multibranched polymer in Formula 1 is as follows: 10 mmol of epoxy halopropane, 10-15 mmol of copper salt, 10-20 mmol of ligand and 200-2000 mmol of alkyl methacrylate are added to a reaction flask, nitrogen is purged to remove oxygen, and the reaction is stirred at 25-80 °C for 2-24 hours. Then, under a nitrogen atmosphere, 200-2000 mmol of dimethylaminoethyl methacrylate is added to the reaction flask, and the reaction is continued at 50-90 °C for 1-24 hours to obtain epoxy-terminated block polymer a. The conversion rate of monomers in the two-step polymerization is 100%. Polyamino compound b and solvent xylene or cyclohexanone are added to the reaction system of the obtained block polymer a, and the reaction is carried out at 25-80 °C for 0.5-10 hours to obtain a multibranched polymer c solution.

[0010] The reactants used in this invention, alkyl methacrylate and dimethylaminoethyl methacrylate, are as follows: Formulas 2 and 3:

[0011] ,

[0012] In the above-mentioned raw material 2, R is a saturated hydrocarbon group with 4 to 16 carbon atoms;

[0013] In the initiator halocyclopropane described in this invention, X is bromine or chlorine;

[0014] The copper salt described in this invention is one of cuprous chloride or cuprous bromide, or a mixture of both.

[0015] The ligands described in this invention are one or a mixture of several of 2,2'-bipyridine, pentamethyldiethylenetriamine, and hexamethyltriethylenetetramine;

[0016] In the ATRP polymerization reaction described in this invention, the ratio of initiator halopropylene oxide to m to n is 1:20~200:20~200;

[0017] In the polyamino compound b described in this invention, x is an integer within the range of 0 to 10;

[0018] Step 2, the preparation process of cuprous oxide and multibranched polymer C composite microcapsules is as follows: Take about 1.0~10 grams of the multibranched block copolymer solution C prepared in Step 1, add 0.5-5 grams of cuprous oxide powder, and stir at a speed of 300~2000 rpm for 10~60 minutes to obtain cuprous oxide and polymer composite microcapsules.

[0019] In step one of this invention, the molar ratio of the epoxy group of polymer a to the active amino hydrogen of polyamino compound b is 1:1~5.

[0020] The mass percentage concentration of the solution formed by the multibranched block copolymer and solvent in this invention is 20-70%; the average particle size of the cuprous oxide powder is less than 50 micrometers.

[0021] Attached image description: Figure 1 This is a schematic diagram showing the release of copper ions from coatings A, B, and C. Detailed Implementation

[0022] The method of the present invention will be further described below with reference to specific embodiments.

[0023] Example 1 Step 1: 10 mmol (0.91 g) epichlorohydrin, 10 mmol (1.00 g) cuprous chloride, 20 mmol (3.46 g) pentamethyldiethylenetriamine and 500 mmol (127.00 g) dodecyl methacrylate were added to a three-necked reaction flask. Nitrogen gas was purged to remove oxygen. After stirring at 80 °C for 2 hours, 500 mmol (78.50 g) of deoxygenated dimethylaminoethyl methacrylate was added to the reaction flask. The reaction was continued at 80 °C for 12 hours. The resulting epoxy-terminated poly(dodecyl methacrylate) 50-b-poly(dimethylaminoethyl methacrylate) 50 was polymer a50. 0.25 g of triethylenetetramine (C6H18N4) and 830 g of xylene solvent were added to the above reaction system. The reaction was carried out at 80 °C for 0.5 hours to obtain a multibranched block polymer c50 solution with a mass concentration of about 20%.

[0024] Take 10 g of the multibranched block copolymer C50 solution prepared in step one, add 0.5 g of cuprous oxide powder, and stir at 300 rpm for 10 minutes to obtain cuprous oxide composite polymer microcapsules D50.

[0025] Example 2 Step 1: 10 mmol (1.34 g) of epichlorohydrin, 10 mmol (1.41 g) of cuprous bromide, 10 mmol (2.30 g) of hexamethyltriethylenetetramine and 800 mmol (203.20 g) of dodecyl methacrylate were added to a three-necked reaction flask. Nitrogen gas was purged to remove oxygen. The reaction was stirred at 40 °C for 15 hours. Then, 800 mmol (125.60 g) of deoxygenated dimethylaminoethyl methacrylate was added to the reaction flask. The reaction was continued at 80 °C for 10 hours. The resulting epoxy-terminated poly(dodecyl methacrylate) 80-b-poly(dimethylaminoethyl methacrylate) 80 was polymer a80. 0.35 g of tetraethylenepentamine (C8H23N5) and 510 g of solvent cyclohexanone were added to the above reaction system. The reaction was carried out at 60 °C for 7 hours to obtain a multi-branched block polymer c80 solution with a mass concentration of about 40%.

[0026] Take 10 g of the multibranched block copolymer C80 solution prepared in step one, add 5 g of cuprous oxide powder, and stir at 1500 rpm for 20 minutes to obtain cuprous oxide composite polymer microcapsules D80.

[0027] Example 3 Step 1: 10 mmol (1.34 g) of epichlorohydrin, 10 mmol (1.41 g) of cuprous bromide, 20 mmol (3.12 g) of 2,2'-bipyridine and 1.0 mol (142.10 g) of butyl methacrylate were added to a three-necked reaction flask. Nitrogen gas was purged to remove oxygen. The reaction was stirred at 35 °C for 24 hours. Then, 1.0 mol (157.00 g) of deoxygenated dimethylaminoethyl methacrylate was added to the reaction flask. The reaction was continued at 80 °C for 24 hours. The resulting epoxy-terminated poly(butyl methacrylate) 100-b-poly(dimethylaminoethyl methacrylate) 100 was polymer a100. 0.35 g of tetraethylenepentamine (C8H23N5) and 300 g of solvent cyclohexanone were added to the above reaction system. The reaction was carried out at 60 °C for 7 hours to obtain a multi-branched block polymer c100 solution with a mass concentration of about 50%.

[0028] Take 10 g of the multibranched block copolymer C100 solution prepared in step one, add 2.5 g of cuprous oxide powder, and stir at 2000 rpm for 40 minutes to obtain cuprous oxide composite polymer microcapsules D100.

[0029] Example 4: Take 4 grams of polymer a80 obtained in Example 2, add 6 grams of cyclohexanone and stir to obtain a polymer a80 cyclohexanone solution of about 40%, and add 5 grams of cuprous oxide powder. Stir at 1500 rpm for 20 minutes to obtain cuprous oxide composite polymer microcapsules da80.

[0030] Example 5: Three portions (20g each) of self-made polycaprolactone resin (molecular weight 80,000) were dissolved in 50ml of cyclohexanone and labeled as Resin A, Resin B, and Resin C, respectively. Then, 5g of cuprous oxide powder was added to Resin A and stirred at 1500 rpm for 20 minutes to obtain Coating A. All cuprous oxide composite polymer microcapsules (da80) prepared in Example 4 were added to Resin B and stirred at 1500 rpm for 20 minutes to obtain Coating B. All cuprous oxide composite polymer microcapsules (d80) prepared in Example 2 were added to Coating C and stirred at 1500 rpm for 20 minutes to obtain Coating C. Three 20cm x 20cm epoxy resin boards were coated with Coatings A, B, and C, respectively. After natural drying for 5 days, Coatings A, B, and C were obtained. The copper ion release rate was tested according to Method A of GB / T6822-2014. The resulting test curves are shown in the appendix. Figure 1 .

[0031] The comparative results of copper ion release in Example 5 above show that, among coatings A, B, and C using biodegradable polycaprolactone as the coating matrix, coating A, lacking the copper ion complexation tertiary amine structure, exhibited a very rapid release rate before 3 weeks. However, after 3 weeks, especially after 8 weeks, its copper ion release was significantly insufficient. Coating B's copper ion release rate was relatively stable compared to coating A, but still fluctuated considerably compared to coating C. Coating C showed very stable copper ion release with minimal fluctuation throughout the entire 16-week experiment. Therefore, it can be inferred that the stable copper ion release in coating C is mainly due to the more stable interaction between the multi-branched, three-dimensional amphiphilic tertiary amine polymer and the coating matrix polymer compared to linear amphiphilic tertiary amine polymers, making it less susceptible to being washed away by interfacial water flow. This fully demonstrates that the multi-branched complex polymer designed and prepared in this invention has a more stable function in regulating copper ion release in marine antifouling coatings, which is precisely the inventive aspect of this invention.

[0032] The preparation method of cuprous oxide and multibranched polymer composite microcapsules provided by the present invention has been described in detail above. Specific examples have been used to illustrate the principle and implementation of the present invention. The above description of the embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the scope of protection of the present invention.

Claims

1. A method for preparing cuprous oxide and multibranched polymer composite microcapsules, the preparation process comprising the following two steps, Step 1, the reaction for preparing the multibranched block polymer is as follows: Equation 1: The preparation process of the multibranched block polymer is as follows: 10 mmol of halopropylene oxide, 10-15 mmol of copper salt, 10-20 mmol of ligand and 200-2000 mmol of alkyl methacrylate are added to a reaction flask, nitrogen gas is purged to remove oxygen, and the reaction is stirred at 25-80°C for 2-24 hours. Then, under a nitrogen atmosphere, 200-2000 mmol of dimethylaminoethyl methacrylate is added to the reaction flask, and the reaction is continued at 50-90°C for 1-24 hours to obtain epoxy-terminated block polymer a. The conversion rate of monomers in the two-step polymerization is 100%. Polyamino compound b and solvent xylene or cyclohexanone are added to the reaction system of polymer a, and the reaction is carried out at 25-80°C for 0.5-10 hours to obtain multibranched block polymer c solution. The reaction raw materials used, alkyl methacrylate and dimethylaminoethyl methacrylate, are as follows: Formulas 2 and 3: In the above-mentioned raw material 2, R is a saturated hydrocarbon group with 4 to 16 carbon atoms; In the initiator halopropylene oxide, X is bromine or chlorine; The copper salt is one of cuprous chloride or cuprous bromide, or a mixture of both. The ligand is one or a mixture of several of 2,2'-bipyridine, pentamethyldiethylenetriamine, and hexamethyltriethylenetetramine; In the ATRP polymerization reaction, the ratio of initiator halopropylene oxide:m:n is 1:20-200:20-200; In polyamino compound b, x is an integer between 0 and 10; Step 2, the preparation process of cuprous oxide composite polymer microcapsules is as follows: Take 1.0-10 g of the multibranched block polymer solution c prepared in Step 1, add 0.5-5 g of cuprous oxide powder, and stir at a speed of 300-2000 rpm for 10-60 minutes to obtain cuprous oxide composite polymer microcapsule solution.

2. The method for preparing cuprous oxide and multibranched polymer composite microcapsules according to claim 1, characterized in that, In step one, the molar ratio of the epoxy group of polymer a to the active amino hydrogen of polyamino compound b is 1:1 to 5.

3. The method for preparing cuprous oxide and multibranched polymer composite microcapsules according to claim 1, characterized in that, The mass percentage concentration of the solution formed by the multibranched block polymer and the solvent is 20-70%; the average particle size of the cuprous oxide powder is less than 50 micrometers.

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