A mussel adhesive protein biomimetic copolymer modified asphalt and a preparation method thereof

Abstract

The application discloses a mussel adhesive protein biomimetic copolymer modified asphalt and a preparation method thereof. The modified asphalt comprises matrix asphalt and a biomimetic copolymer formed by copolymerization of catechol structural units and a free radical initiating monomer. The biomimetic copolymer can form a dynamic network in the asphalt system through hydrogen bonding, pi-pi interaction and metal coordination, and form a strong adhesion layer on the aggregate surface, thereby significantly improving the adhesion and water damage resistance of the asphalt. At the same time, the free radical initiating monomer can react with asphalt aging free radicals under ultraviolet irradiation, effectively terminating the aging process and imparting excellent ultraviolet aging resistance to the modified asphalt. The preparation method is simple, suitable for industrial production, and particularly suitable for road engineering in the hot and humid regions of South China.

Description

Technical Field

[0001] This invention relates to the fields of road engineering materials and biomimetic polymer materials, and particularly to a mussel adhesive protein biomimetic copolymer modified asphalt and its preparation method. Background Technology

[0002] In hot and humid regions such as South my country, asphalt pavements are subjected to harsh environments including high temperature, high humidity, strong ultraviolet radiation, and heavy traffic for extended periods. This places extremely high demands on the high-temperature stability, adhesion to aggregates, and anti-aging properties of asphalt binders. Existing ordinary asphalt and common modified asphalt (such as SBS modified asphalt) are prone to rutting, spalling, potholes, and other defects in these environments, exhibiting insufficient resistance to water damage and long-term durability.

[0003] Mussel adhesive proteins, rich in catechol structural units, can achieve strong adhesion in wet environments through various mechanisms such as hydrogen bonding, π-π stacking, and metal ion coordination. This biomimetic principle provides a new approach to improving asphalt performance. Existing technologies have attempted to introduce catechol structural units into asphalt systems, such as L-DMA modified asphalt or bone glue-dopamine modified asphalt. These approaches have improved the adhesion and high-temperature performance of asphalt to some extent, but their improvement in anti-aging properties is limited, especially in resisting UV aging.

[0004] Therefore, it is of great significance to develop a new type of modified asphalt material that can significantly improve asphalt adhesion, water damage resistance, and aging resistance (especially UV aging resistance). Summary of the Invention

[0005] In view of this, the present invention provides a high-performance mussel adhesive protein biomimetic copolymer modified asphalt and its preparation method. This modified asphalt, through biomimetic design, significantly improves its adhesion properties, water damage resistance, and aging resistance under humid, hot, heavy-load, and strong ultraviolet environments.

[0006] The technical solution of this invention is implemented as follows:

[0007] In a first aspect, a mussel adhesive protein biomimetic copolymer modified bitumen comprises a base bitumen and a mussel biomimetic copolymer; the mussel biomimetic copolymer is obtained by a monomer reaction initiated by catechol structural units and free radicals.

[0008] Based on the above technical solutions, preferably, the mussel biomimetic copolymer further includes an initiator, and the mussel biomimetic copolymer is obtained by free radical polymerization of catechol structural units and free radical initiating monomers under the catalysis of the initiator in an inert atmosphere.

[0009] More preferably, the inert atmosphere is a nitrogen or argon atmosphere. The initiator is added after deoxygenation under an inert atmosphere. After the reaction is complete, the polymerization product is subjected to precipitation and extraction to remove residual monomers and the aqueous phase, and then vacuum dried at 40-70℃ to constant weight to obtain a mussel adhesive protein biomimetic copolymer.

[0010] More preferably, the initiator includes one or more of azobisisobutyronitrile, benzoyl peroxide, and dicumyl peroxide, and the amount of initiator added is 0.1-2 wt% of the mass of the base asphalt.

[0011] More preferably, the polymerization reaction temperature is 50-90℃ and the reaction time is 2-10h.

[0012] More preferably, the polymerization reaction is carried out in a solvent, which includes one or more of N,N-dimethylformamide, dimethyl sulfoxide, or N-methyl-2-pyrrolidone.

[0013] Further preferably, the catechol structural unit is a polymerizable monomer containing a catechol group. The catechol structural unit is prepared by reacting a catechol-containing dopamine substance with an acryloyl anhydride or its active derivative under alkaline conditions. The catechol dopamine substance is one or more of dopamine hydrochloride, levodopa, or a combination thereof; more preferably, the catechol dopamine substance is levodopa.

[0014] More preferably, the polymerizable monomer containing catechol groups includes one or more of methacrylic anhydride-DOPA hydrochloride, methacrylic anhydride-L-DOPA, methacrylic anhydride-chitosan, and anhydride derivatives containing catechol groups.

[0015] More preferably, the free radical initiating monomer includes one or more of butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, lauryl acrylate, hexadecyl acrylate, octadecyl acrylate, and hydroxyethyl acrylate.

[0016] More preferably, the amount of the mussel biomimetic copolymer added is 2-8 wt% of the mass of the base asphalt.

[0017] More preferably, based on the total mass of the mussel biomimetic copolymer as 100%, the mass percentage of the catechol structural unit is 5%-30%, and the mass percentage of the free radical initiating monomer is 70%-95%.

[0018] More preferably, the mass percentage of catechin structural units is 10%-20%.

[0019] More preferably, the modified asphalt further includes a metal ion donor. The metal ion donor is one or a mixture of two or more of ferric chloride, ferrous sulfate, calcium chloride, and magnesium chloride, which can release Fe... 3+ Fe 2+ Mg 2+ or Ca 2+ Salts or complexes of metal ions are used to form coordination crosslinks with catechol structural units, and the amount of metal ion donor added is 0.001-1 wt% of the mass of the matrix bitumen.

[0020] In a second aspect, the present invention provides a method for preparing the modified asphalt described in the first aspect, comprising the following steps: heating the base asphalt to 120-180°C, adding the mussel biomimetic copolymer, and shearing to obtain the modified asphalt.

[0021] Based on the above technical solutions, preferably, after adding the biomimetic copolymer, the mixture is sheared at 2000-6000 rpm for 20-120 min, and after adding the metal ion donor, it is sheared for another 10-60 min. This allows the catechol structural units to form reversible coordination crosslinks with the metal ions, further improving wet adhesion and resistance to high-temperature deformation.

[0022] This invention uses a free radical polymerization method to obtain a biomimetic copolymer of mussel adhesive protein structural units by combining catechin structural units and flexible monomers. While simulating the adhesion mechanism of mussel adhesive protein, it introduces anti-aging monomers containing ester and ether groups, so that the copolymer segments form a stable microstructure network in asphalt, thereby significantly improving the performance of asphalt under thermo-oxidative and ultraviolet aging conditions.

[0023] Compared with existing asphalt binders, the present invention has at least one or more of the following advantages:

[0024] (1) Wet adhesion enhancement: The modifier provided by the present invention simulates the adhesion mechanism of mussels in the ocean. The biomimetic copolymer and asphalt are mainly interacted by physical interactions such as hydrogen bonds, π-π bonds, and π-cationic bonds. In the presence of metal ions, catechol-metal coordination bonds are formed, thereby achieving multiple bonding enhancement, which can significantly improve the water damage resistance and spalling resistance of the asphalt-aggregate interface.

[0025] (2) Improved aging resistance: The polar interaction between the ester group and ether oxygen in the free radical initiator monomer and the asphalt and its oxidation products can hinder the aggregation of asphaltenes. At the same time, the free radical initiator monomer can generate free radicals under UV irradiation, which then undergo free radical polymerization reaction with the peroxide free radicals in the asphalt, thus terminating the asphalt aging process. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the molecular structure of Example 1 of the biomimetic copolymer of mussel protein structural units of the present invention;

[0028] Figure 2 This is a schematic diagram of the molecular structure of Example 7 of the biomimetic copolymer of mussel protein structural units of the present invention;

[0029] Figure 3 This is a schematic diagram illustrating the mechanism of action of the biomimetic copolymer modified asphalt with mussel adhesive protein structural units of the present invention. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] Table 1: Material Source Description Table

[0032] .

[0033] Example 1

[0034] A biomimetic copolymer-modified asphalt containing mussel adhesive protein structural units and its preparation method, comprising the following steps:

[0035] S1. Prepare a weakly alkaline buffer solution by dissolving 24 g of sodium tetraborate and 10 g of sodium bicarbonate in 200 mL of deionized water, and add 10.4 g of levodopa to the buffer. Then, slowly add 9.5 g of methacrylic anhydride dissolved in 50 mL of tetrahydrofuran to the buffer solution. Adjust the pH to ≥8 using sodium hydroxide solution and stir the mixture under light-protected conditions for approximately 18 h. After the reaction is complete, adjust the pH to less than 2 using 4 mol / L hydrochloric acid solution, extract with 100 mL of ethyl acetate, and collect the organic phase. Concentrate the organic phase to 50 mL. Add the concentrated ethyl acetate solution to 400 mL of cyclohexane and continue stirring for 30 min. Then, allow it to recrystallize completely at 4 °C for 18 h. Finally, filter out the solid and dry it to obtain the polymerizable unit L-DMA containing catechol and vinyl structural units.

[0036] S2. Weigh 10 g L-DMA, 90 g butyl acrylate (BA), and 0.5 g AIBN, and dissolve them in 100 g DMF to obtain a copolymer solution. After deoxygenation of the solution under a nitrogen atmosphere, heat to 80°C and maintain stirring for approximately 12 h. After the reaction is complete, precipitate the reaction solution, filter out the solid, wash, and dry until the mass is constant to obtain the mussel biomimetic copolymer P(BA-co-L-DMA).

[0037] S3. Take 500 g of 70# base asphalt and heat it to approximately 145°C until it melts uniformly. Add 10 g of the above-mentioned biomimetic copolymer (2% of the asphalt mass) to it, and shear it at 4000 rpm for 60 min at 145°C using a high-speed shearing machine to fully swell and uniformly disperse the copolymer in the asphalt. After shearing, place the system in a 140°C oven and let it stand for about 2 h to develop, obtaining the biomimetic copolymer modified asphalt sample of Example 1.

[0038] Performance testing: Penetration, ductility, softening point, and rotational viscosity tests were conducted according to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011). Aged asphalt was prepared using the Rotational Film Heat Aging Test (RTFOT method) in the specification, and the penetration and ductility of the aged asphalt were measured. The penetration ratio before and after aging was calculated, and the results are summarized in Table 2.

[0039] The inventors used the Marshall design method to prepare AC-13 type dense-graded asphalt concrete specimens from the asphalt samples of Examples 1-10 and Comparative Examples 1-6. The specimens had a suspended dense structure. Freeze-thaw splitting test and immersion Marshall test were conducted to test their resistance to water damage. The results are summarized in Table 3.

[0040] Test results show that the biomimetic copolymer modified asphalt of this invention has significant improvements over the base asphalt in terms of penetration, ductility, residual penetration ratio, RTFOT post-ductility, residual stability, and freeze-thaw splitting tensile strength ratio (TSR).

[0041] Example 2

[0042] A biomimetic copolymer-modified asphalt containing mussel adhesive protein structural units and its preparation method, comprising the following steps:

[0043] S1. Prepare a weakly alkaline buffer solution by dissolving 24 g of sodium tetraborate and 10 g of sodium bicarbonate in 200 mL of deionized water, and add 10 g of dopa hydrochloride to the buffer. Then, slowly add 9.4 mL of methacrylic anhydride dissolved in 50 mL of tetrahydrofuran to the buffer solution. Adjust the pH to ≥8 using sodium hydroxide solution and stir the mixture under light-protected conditions for approximately 18 h. After the reaction is complete, adjust the pH to less than 2 using 4 mol / L hydrochloric acid solution, extract with 100 mL of ethyl acetate, and collect the organic phase. Concentrate the organic phase to 50 mL. Add the concentrated ethyl acetate solution to 400 mL of cyclohexane and continue stirring for 30 min. Then, allow it to recrystallize completely at 4 °C for 18 h. Finally, filter out the solid and dry it to obtain the polymerizable unit DMA containing catechol and vinyl structural units.

[0044] S2. Weigh 20 g DMA, 80 g methoxyethyl acrylate (MEA), and 0.5 g azobisisobutyronitrile (AIBN), and dissolve them in 100 g pyrrolidone to obtain a copolymer solution. After deoxygenation of the solution under a nitrogen atmosphere, heat to 60°C and maintain stirring for approximately 2 hours. After the reaction is complete, precipitate the reaction solution, filter out the solid, wash, and dry until the mass is constant to obtain the mussel biomimetic copolymer P(MEA-co-DMA).

[0045] S3. Take 500 g of 70# base asphalt and heat it to approximately 180°C until it melts uniformly. Add 10 g of the above-mentioned biomimetic copolymer (2% of the asphalt mass) to it, and shear it at 8000 rpm for 20 min at 180°C using a high-speed shearing machine to fully swell and uniformly disperse the copolymer in the asphalt. After shearing, place the system in a 140°C oven and let it stand for about 2 h to develop, obtaining the biomimetic copolymer modified asphalt sample of Example 2.

[0046] The performance test results are shown in Tables 2 and 3.

[0047] Example 3

[0048] A biomimetic copolymer-modified asphalt containing mussel adhesive protein structural units and its preparation method, comprising the following steps:

[0049] S1. Add 10g of chitosan to 340ml of acetic acid solution; then slowly add 35g of methacrylic anhydride to the above solution and stir the reaction at room temperature for about 5 hours. After the reaction is complete, dilute with an equal volume of deionized water and dialyze through a 14kDa dialysis bag for 2 days. Freeze-dry the resulting mixture at -20℃ to obtain methacrylated chitosan (CSMA).

[0050] S2. Weigh 30 g CSMA, 70 g lauryl acrylate (LA), and 0.5 g dicumyl peroxide (DCP), and dissolve them in 100 g DMSO to obtain a copolymer solution. After deoxygenation of the solution under a nitrogen atmosphere, heat to 50°C and maintain stirring for approximately 12 h. After the reaction is complete, precipitate the reaction solution, filter out the solid, wash, and dry to constant mass to obtain the mussel biomimetic copolymer P(LA-co-CSMA).

[0051] S3. Take 500 g of 70# base asphalt and heat it to approximately 120°C until it melts uniformly. Add 10 g of the above-mentioned biomimetic copolymer (2% of the asphalt mass) to it, and shear it at 2000 rpm for 120 min at 120°C using a high-speed shearing machine to fully swell and uniformly disperse the copolymer in the asphalt. After shearing, place the system in a 140°C oven and let it stand for about 2 h to develop, obtaining the biomimetic copolymer modified asphalt sample of Example 3.

[0052] The performance test results are shown in Tables 2 and 3.

[0053] Example 4

[0054] A biomimetic copolymer-modified asphalt with mussel adhesive protein structural units and its preparation method, compared with Example 1, includes the following steps:

[0055] S1, the synthesis of the catechol unit (L-DMA) is the same as in Example 1.

[0056] S2, the mussel biomimetic adhesive copolymer is P(EMA-co-L-DMA), and the synthesis steps are as follows: 10g L-DMA, 90g methoxyethyl acrylate (EMA) and 0.5g AIBN are weighed and dissolved in 100mL N-methyl-2-pyrrolidone (NMP). The mixture is stirred at 80℃ under a nitrogen atmosphere for about 12 h. After the reaction is completed, precipitation, washing and vacuum drying are performed to obtain the P(EMA-co-L-DMA) copolymer.

[0057] S3. The preparation of modified asphalt is the same as in Example 1; the performance testing is the same as in Example 1.

[0058] The performance test results are shown in Tables 2 and 3.

[0059] Examples 5-6

[0060] The difference from Example 1 is that the amount of mussel biomimetic copolymer added to the asphalt was 25g (5% of the asphalt mass) and 40g (8% of the asphalt mass), respectively. The performance test results are shown in Tables 2 and 3.

[0061] Examples 7-9

[0062] The difference from Example 1 is that in step S3, the system was sheared at 4000 rpm for 60 min at 145°C using a high-speed shearing machine. Then, 0.005 g (0.001% of the asphalt mass) of ferric chloride (metal ion donor) was added and sheared at 4000 rpm for 30 min; 1 g (0.2% of the asphalt mass) of calcium chloride (metal ion donor) was added and sheared at 4000 rpm for 10 min; and 5 g (1% of the asphalt mass) of ferric chloride (metal ion donor) was added and sheared at 4000 rpm for 60 min. After shearing, the system was placed in a 140°C oven for static development for approximately 2 h. The remaining steps were the same as in Example 1, and the performance test results are shown in Tables 2 and 3.

[0063] Example 10

[0064] The difference from Example 1 is that in step S2, 30 g of L-DMA and 70 g of butyl acrylate (BA) were weighed. The remaining steps are the same as in Example 1, and the performance test results are shown in Tables 2 and 3.

[0065] Comparative Examples 1-2:

[0066] The performance test results of 70# base asphalt and commercially available SBS (IC) modified asphalt (SBS content 4%) are shown in Tables 2 and 3.

[0067] Comparative Examples 3-4:

[0068] The difference from Example 4 is that the mass of L-DMA and BA in BA-co-L-DMA is 30g and 70g, respectively, and the mussel biomimetic copolymer added to the asphalt is 5g (accounting for 1% of the asphalt mass) and 50g (accounting for 10% of the asphalt mass), respectively. The remaining steps are the same as in Example 1, and the performance test results are shown in Tables 2 and 3.

[0069] Comparative Examples 5-6:

[0070] The difference from Example 1 is that in Comparative Example 5, the mass of L-DMA and BA in BA-co-L-DMA is 3g and 97g, respectively; in Comparative Example 6, the mass of L-DMA and BA in BA-co-L-DMA is 35g and 65g, respectively; the remaining steps are the same as in Example 1, and the performance test results are shown in Tables 2 and 3.

[0071] Table 2:

[0072]

[0073] Table 3:

[0074]

[0075] As shown in Table 2, compared with the base asphalt, the asphalt modified by the biomimetic copolymer of mussel protein structural units of this invention has a lower penetration, higher viscosity, and higher softening point, indicating that the modified asphalt has enhanced adhesion and shear resistance, and improved high-temperature stability. The performance degradation caused by aging in the RTFOT test is significantly reduced, indicating that the biomimetic copolymer significantly improves the anti-aging properties of the asphalt.

[0076] As shown in Table 3, the asphalt modified with the biomimetic copolymer of mussel protein structural units of the present invention has significantly greater stability after immersion test than the base asphalt. This proves that introducing an appropriate amount of biomimetic copolymer of mussel adhesive protein structural units is beneficial to enhancing the wet adhesion and water damage resistance of the asphalt-aggregate interface. Furthermore, the tensile strength of the aged asphalt mixture is also improved compared to the control ratio, proving that adding copolymer can improve the anti-aging ability of asphalt.

[0077] This invention Figure 3 The diagram illustrates the network structure formed by the biomimetic copolymer in the asphalt matrix and the biomimetic adhesion reinforcement layer formed at the asphalt-aggregate interface. The figures show how the biomimetic copolymer and asphalt achieve multiple bonding enhancements to the asphalt's various properties through hydrogen bonds, catechol-metal coordination bonds, π-π bonds, and π-cationic bonds, primarily through physical interactions with coordination crosslinking as a secondary component.

[0078] As can be seen from Examples 1-4, the biomimetic copolymer structures of mussels synthesized from different materials have a significant impact on the properties of asphalt.

[0079] As can be seen from Examples 5-6 and Comparative Examples 3-4, as the mass ratio of the biomimetic copolymer of mussel protein structural units in asphalt increases, the modified asphalt's resistance to water damage and its anti-aging properties both increase.

[0080] Examples 7-9 show that the introduction of metal ions significantly enhances the performance of biomimetic copolymer-modified asphalt. With increasing metal ion content, the modified asphalt exhibits improved resistance to water damage and aging.

[0081] Comparing Example 1 and Example 10, it can be seen that when the content of polymerizable monomers containing catechol groups increases, the system can provide sufficient polar biomimetic adhesion sites to enhance the interaction and structural stability with the polar components of asphalt, while maintaining a certain degree of flexibility, thereby improving penetration and low-temperature ductility. However, a decrease in the content of free radical initiating monomers leads to an increase in free radicals in the asphalt, thus reducing its anti-aging properties.

[0082] Comparative Examples 3 and 4 represent examples with insufficient and excessive amounts of the mussel biomimetic copolymer. Compared to Example 1, it is evident that when the copolymer content is too low, the biomimetic copolymer struggles to form effective interfacial interactions and structural reinforcement in the asphalt system, thus limiting its improvement on the asphalt's anti-aging properties and wet adhesion / water damage resistance. Conversely, when the copolymer content is too high, although the system's high-temperature stability may continue to improve, it can easily lead to excessive hardening of the asphalt system, decreased toughness and low-temperature ductility, and may even result in diminishing marginal returns or deterioration of overall road performance due to incomplete compatibility. These results indicate that the amount of mussel biomimetic copolymer added to asphalt needs to be controlled within a reasonable range to achieve a balance between high-temperature stability, anti-aging properties, and low-temperature toughness.

[0083] Comparative Examples 5 and 6 represent examples with excessively low and high amounts of catechin units. Compared to Example 1, it can be seen that when the L-DMA content is too low, the number of catechin groups is insufficient, making it difficult to fully exert its enhancing effect on wet adhesion and water damage resistance at the asphalt-aggregate interface, while the improvement in anti-aging performance is also not significant. Conversely, when the L-DMA content is too high, the system has too many polar / active sites, easily leading to stronger complexation / crosslinking and structural rigidity, increasing the material's embrittlement tendency, decreasing low-temperature toughness and ductility, and thus not necessarily further improving overall performance. This result indicates that the proportion of catechin structural units in the copolymer also has an optimal range; both excessively low and excessively high proportions are detrimental to obtaining optimal overall road performance.

[0084] In summary, the mussel adhesive protein biomimetic copolymer modified asphalt of this invention not only has good water loss resistance but also anti-aging properties. As shown in Tables 2 and 3, Example 6, with the same modified asphalt content of 8%, exhibits the best anti-aging and water loss resistance.

[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A biomimetic copolymer-modified asphalt containing mussel adhesive protein, characterized in that, It includes a base bitumen and a mussel biomimetic copolymer; the mussel biomimetic copolymer is obtained by a monomer reaction initiated by catechol structural units and free radicals; The amount of the mussel biomimetic copolymer added is 2-8 wt% of the matrix asphalt mass; Based on the total mass of the mussel biomimetic copolymer as 100%, the mass percentage of the catechol structural unit is 5%-30%, and the mass percentage of the free radical initiating monomer is 70%-95%. The catechol structural unit includes at least one of methacrylic anhydride-DOPA hydrochloride, methacrylic anhydride-L-DOPA, and methacrylic anhydride-chitosan; the free radical initiating monomer includes at least one of butyl acrylate, methoxyethyl acrylate, and lauryl acrylate.

2. The modified asphalt as described in claim 1, characterized in that, The mussel biomimetic copolymer also includes an initiator. The mussel biomimetic copolymer is obtained by free radical polymerization of catechol structural units and free radical initiating monomers under the catalysis of the initiator in an inert atmosphere.

3. The modified asphalt as described in claim 1, characterized in that, It also includes metal ion donors.

4. A method for preparing modified asphalt as described in any one of claims 1 to 3, characterized in that, The process includes the following steps: heating the base asphalt to 120-180℃, adding the mussel biomimetic copolymer, and shearing to obtain the modified asphalt.

5. The method for preparing modified asphalt as described in claim 4, characterized in that, After adding the mussel biomimetic copolymer, the mixture was sheared at 2000-6000 rpm for 20-120 min, and then sheared for another 10-60 min after adding the metal ion donor.

Images