Silane-modified bidirectional shape memory liquid crystal elastomer (SMLCE) and preparation method of crack pouring adhesive compounded by same and asphalt

Abstract

The invention relates to the technical field of crack pouring adhesives, in particular to a silane modified bidirectional shape memory liquid crystal elastomer (SMLCE) and a preparation method of the crack pouring adhesive compounded with asphalt, and the preparation method comprises the following steps: step 1, mixing a chain extender EDDET and a cross-linking agent PETMP according to a certain proportion, and polymerizing a liquid crystal monomer RM257 under the catalytic action of DPA (dipropylamine) to prepare an SMLCE material; and 2, selecting a silane coupling agent to carry out silane modification on the SMLCE, and determining the optimal ratio of the silane coupling agent to the SMLCE, wherein the obtained modified SMLCE can be called Si-SMLCE. And 3, determining which proportion of the Si-SMLCE material and asphalt can be mixed to prepare the crack pouring adhesive capable of adapting to dynamic opening and closing of asphalt pavement cracks in a large-temperature-difference region. The SMLCE material is subjected to silane modification through the silane coupling agent KH-550, so that the SMLCE material can be compounded with asphalt, and the crack pouring adhesive which can adapt to dynamic opening and closing of asphalt pavement cracks in large-temperature-difference regions, has shape memory and is good in economical efficiency is developed.

Description

Technical Field

[0001] The present invention relates to the technical field of crack caulking glue, and in particular to a method for preparing a crack caulking glue of a silane-modified two-way shape memory liquid crystal elastomer (SMLCE) and a compound thereof with asphalt. Background Art

[0002] Asphalt pavements are prone to cracking during long-term service due to factors such as temperature cycling, traffic loads, and environmental aging. Traditional repair materials primarily include hot-melt sealants and cold-patch polymer-modified asphalt, but both have significant performance flaws. Hot-melt sealants are less temperature-sensitive, tending to soften at high temperatures and become brittle at low temperatures, leading to peeling. Furthermore, the modulus of this type of sealant differs significantly from that of asphalt, making stress concentration issues more likely during temperature cycling, leading to material peeling. Cold-patch polymer-modified asphalt cures slowly at low temperatures, bubbles easily at high temperatures, and has insufficient deformability, with an elongation at break generally ≤150%, making it unable to adapt to the dynamic opening and closing of cracks.

[0003] Shape memory elastic crystals (SMLCEs) have become a new generation of intelligent repair materials due to their programmable bidirectional deformation and high recovery stress. However, they are prone to the following problems during the repair of asphalt pavement cracks:

[0004] ① Expensive. The liquid crystal monomer RM257 that makes up SMLCE is relatively expensive, making its sole use in asphalt pavement crack repair uneconomical. ② Although SMLCE exhibits shape memory, adapting to the dynamic opening and closing of asphalt pavement cracks, its hydrophobic surface has a weak bond with the polar components of asphalt, making it susceptible to delamination during construction and use. ③ SMLCE is suitable for repairing asphalt pavement cracks in regions with large temperature fluctuations, but there are currently no quantitative indicators for evaluating the effectiveness of asphalt pavement crack repairs in such environments.

[0005] Therefore, it is necessary to provide a silane-modified two-way shape memory liquid crystal elastomer (Si-SMLCE) and a method for preparing a caulking glue compounded with asphalt to solve the above problems. Summary of the Invention

[0006] In view of the defects of the prior art, the purpose of the present invention is to provide a silane-modified two-way shape memory liquid crystal elastomer (SMLCE) and a method for preparing a caulking glue compounded with asphalt, so as to solve the problems raised in the above background technology.

[0007] The present invention solves the technical problem by adopting the following technical solutions:

[0008] A method for preparing a silane-modified two-way shape memory liquid crystal elastomer (SMLCE) and a crack filling adhesive compounded with asphalt, comprising the following steps:

[0009] Step 1: The chain extender EDDET and the cross-linker PETMP are mixed in a certain proportion, and the liquid crystal monomer RM257 is polymerized through two cross-linking processes under the catalysis of DPA (dipropylamine) to prepare an SMLCE material with excellent performance and two-way shape memory.

[0010] Step 2: Silane modification of SMLCE: Select a silane coupling agent and determine the optimal ratio between it and SMLCE, so as to achieve the effect of not changing the two-way shape memory deformation properties of SMLCE and not causing excessive cross-linking that makes the material brittle.

[0011] Step 3: Determine the mixing ratio of silane-modified SMLCE material (Si-SMLCE) and matrix asphalt to prepare a caulking adhesive that can adapt to the dynamic opening and closing of cracks in asphalt pavements in areas with large temperature differences.

[0012] Preferably, when designing the formula in step 1, the optimal molar ratio of the crosslinking agent PETMP to the chain extender EDDET is 1:15, and the amount of RM257 is calculated based on this.

[0013] When designing the formula for step 2, γ-aminopropyltriethoxysilane (KH-550) is selected as the silane coupling agent. The amino group in the silane coupling agent can react with the exposed hydroxyl groups in SMLCE to generate stable Si-O-Si covalent bonds. After the reaction, the silane coupling agent only plays a role in surface modification of SMLCE, forming an interface transition layer, without destroying the internal cross-linked network, that is, it will not change the two-way shape memory properties of SMLCE.

[0014] In step 2, the addition amount of KH-550 is 0.5%-2% of the mass of SMLCE. If the addition amount is less than 0.5%, the interface modification is insufficient. If the addition amount is greater than 2%, silane self-aggregates to form particles, resulting in stress concentration problems. The molecular structure of KH-550 is:

[0015] .

[0016] Preferably, when designing the formula in step three, the matrix asphalt is preferably selected to be No. 70-90, and the mass ratio to Si-SMLCE is 1:3-1:5. The specific ratio needs to be determined through theoretical calculation and orthogonal experiment.

[0017] Preferably, the method specifically includes the following steps:

[0018] SMLCE synthesis: RM257, PETMP, and EDDET were dissolved in tetrahydrofuran (THF) at a certain ratio, and a catalyst (DPA) (0.5% by weight of RM257) was added. Pre-crosslinking was performed at 25°C under vacuum for 1.5 hours, and then secondary crosslinking was completed by stretching at a stretching angle of 150%.

[0019] Silane modification: SMLCE was dissolved in THF, KH-550 was added, and the mixture was stirred at 60°C for 2 hours under nitrogen protection to generate Si-SMLCE;

[0020] Asphalt compounding: Si-SMLCE was shear mixed with No. 70-90 base asphalt at 160°C and 3000 rpm for 30 minutes.

[0021] Preferably, the base asphalt is SBS modified asphalt or rubber modified asphalt, and its needle penetration (25°C) is 60-100 dmm.

[0022] The performance of Si-SMLCE should meet the following indicators: ① Bidirectional shape memory deformation rate: ≥40% in the range of -20℃ to 120℃; ② Phase change temperature (Tc) should be between 65℃ and 70℃; ③ Peel strength with asphalt should be ≥1.5MPa (50%-80% higher than unmodified SMLCE); ④ Elongation at break should be ≥250%.

[0023] The repair effect of a silane-modified bidirectional shape memory liquid crystal elastomer and its asphalt-compounded caulking adhesive was evaluated. After the prepared asphalt-compounded caulking adhesive was cyclically loaded 100 times at a temperature of -20°C to 60°C, there should be no peeling at the interface and the deformation rate attenuation should be ≤5%.

[0024] A method for preparing a silane-modified two-way shape memory liquid crystal elastomer (Si-SMLCE) and a crack filling adhesive compounded with asphalt, wherein the design method comprises the following steps:

[0025] Step 1: Preparation of shape memory material SMLCE

[0026] The shape memory material (SMLCE) is synthesized by polymerization of the liquid crystal monomer RM257, the crosslinker PETMP, and the chain extender EDDET under the catalysis of DPA (dipropylamine). RM257 (1,4-bis[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene) is a liquid crystal material. Its benzoyloxy chains form an ordered liquid crystal phase under oriented stretching, driving bidirectional deformation. The four thiol functional groups (-SH) of the crosslinker PETMP (3-mercaptopropionate) interact with the acrylic acid double bonds of RM257 through a click reaction to form a three-dimensional network. The crosslink density directly affects the material's rigidity and deformation recovery. The dithiol functional groups of the chain extender EDDET (3,6-dioxa-1,8-octanedithiol) extend the backbone chain, regulating molecular chain flexibility and the degree of freedom of liquid crystal alignment. In order for the materials to react fully, RM257, PETMP and EDDET should have an appropriate molar ratio, where the molar ratio of PETMP to EDDET is 1:15, and the amount of RM257 should be theoretically calculated based on the number of functional groups involved in the reaction.

[0027] Step 2: Silane modification of SMLCE

[0028] First, prepare an SMLCE material with excellent performance according to the proportion of step one, then dissolve the prepared SMLCE film in THF, add KH-550 of preferred quality, heat and stir in a water bath at 60°C under a nitrogen environment for 2 hours, centrifuge to remove unreacted silane, and then pour the centrifuged solution into a mold, vacuum dry it in a vacuum oven at 60°C to constant weight, and obtain a Si-SMLCE sample.

[0029] Calculation of silane coupling agent dosage: The theoretical prediction method can be used to preliminarily estimate the saturated adsorption capacity of silane, determine the dosage range, and then optimize the material ratio through orthogonal experiments:

[0030] First, it is assumed that the silane molecules cover the SMLCE surface in a monolayer and there is no self-aggregation phenomenon; the hydroxyl density on the SMLCE surface is N OH ≈5×10 18 groups / m 2 (Typical value), the theoretical saturation dosage calculation formula is:

[0031]

[0032] Where A is the specific surface area of SMLCE (approximately 10m 2 / g); M Si is the molar mass of KH-550 (221.4 g / mol); N A is Avogadro's constant (6.022×10 23 mol -1 );

[0033] The amount of KH-550 was determined as described above. During the preparation process, SMLCE was dissolved in THF, and a preferred amount of KH-550 was added. The mixture was stirred at 60°C under nitrogen for 2 hours, and then the unreacted silane was removed by centrifugation. The mixture was then vacuum dried at 60°C to a constant weight. The reaction equation is:

[0034] Step 3: Determine the mixing ratio of Si-SMLCE and asphalt

[0035] The matrix asphalt is preferably SBS modified asphalt (softening point ≥ 80°C). The addition amount of conventional polymers (such as SBS, rubber) is usually 3%-10%. However, after the SMLCE material is compounded with asphalt, it needs to have shape memory function. The initial ratio range can be set to a ratio of Si-SMLCE to asphalt of 1:3-1:5. The compounding ratio can be estimated by the following theoretical model. According to the volume fraction of SMLCE ( ) predicts the composite modulus (Guth-Gold formula):

[0036]

[0037] Among them, Gc is the compliance modulus, Gm is the asphalt modulus, is the volume proportion of SMLCE.

[0038] The specific compounding ratio of Si-SMLCE and asphalt can be determined by orthogonal experiments, and the evaluation indicators are: shape memory deformation rate (Rs), peel strength and elongation at break ( ), where the shape memory deformation rate (Rs) is tested by DMA temperature cycle test Determination, peel strength test according to ASTM D903 standard, elongation at break ( ) was determined by ASTM D638 tensile test.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] This invention modifies SMLCE material with the silane coupling agent KH-550, enabling its compounding with asphalt. This not only significantly reduces the cost of the repair material but also improves its compatibility with asphalt pavement cracks, effectively reducing secondary damage caused by the repeated dynamic opening and closing of asphalt pavement cracks in areas with large temperature differences. This invention proposes a mechanism for evaluating the effectiveness of asphalt pavement crack repairs in areas with large temperature differences, and proposes relatively accurate evaluation indicators, providing a reference for evaluating the effectiveness of asphalt pavement crack repairs in areas with large temperature differences. DETAILED DESCRIPTION

[0041] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] The present embodiment provides a method for preparing a silane-modified two-way shape memory liquid crystal elastomer (SMLCE) and a crack filling adhesive compounded with asphalt, comprising the following steps:

[0043] Step 1: The chain extender EDDET and the cross-linker PETMP are mixed in a certain proportion, and the liquid crystal monomer RM257 is polymerized through two cross-linking processes under the catalysis of DPA (dipropylamine) to prepare an SMLCE material with excellent performance and two-way shape memory.

[0044] Step 2: Silane modification of SMLCE: Select a silane coupling agent and determine the optimal ratio between it and SMLCE, so as to achieve the effect of not changing the two-way shape memory deformation properties of SMLCE and not causing excessive cross-linking that makes the material brittle.

[0045] Step 3: Determine the mixing ratio of silane-modified SMLCE material (Si-SMLCE) and matrix asphalt to prepare a caulking adhesive that can adapt to the dynamic opening and closing of cracks in asphalt pavements in areas with large temperature differences.

[0046] In the formulation design of step 1 of this embodiment, the optimal molar ratio of the cross-linking agent PETMP to the chain extender EDDET was 1:15, and the amount of RM257 was calculated based on this ratio.

[0047] When designing the formula for step 2 of this embodiment, γ-aminopropyltriethoxysilane (KH-550) is selected as the silane coupling agent. The amino group in the silane coupling agent can react with the exposed hydroxyl groups in SMLCE to generate stable Si-O-Si covalent bonds. After the reaction, the silane coupling agent only plays a role in surface modification of SMLCE, forming an interface transition layer, without destroying the internal cross-linked network, that is, it will not change the two-way shape memory properties of SMLCE.

[0048] In step 2 of this embodiment, the amount of KH-550 added is 0.5%-2% of the mass of SMLCE. If the amount added is less than 0.5%, insufficient interface modification will occur. If the amount added is greater than 2%, silane will self-aggregate to form particles, leading to stress concentration problems. The molecular structure of KH-550 is:

[0049] .

[0050] When designing the formula in step 3 of this embodiment, the matrix asphalt is preferably selected from No. 70-90, and the mass ratio of the matrix asphalt to Si-SMLCE is 1:3-1:5. The specific ratio needs to be determined through theoretical calculation and orthogonal test.

[0051] This embodiment specifically includes the following steps:

[0052] SMLCE synthesis: RM257, PETMP, and EDDET were dissolved in tetrahydrofuran (THF) at a certain ratio, and a catalyst (DPA) (0.5% by weight of RM257) was added. Pre-crosslinking was performed at 25°C under vacuum for 1.5 hours, and then secondary crosslinking was completed by stretching at a stretching angle of 150%.

[0053] Silane modification: SMLCE was dissolved in THF, KH-550 was added, and the mixture was stirred at 60°C for 2 hours under nitrogen protection to generate Si-SMLCE;

[0054] Asphalt compounding: Si-SMLCE was shear mixed with No. 70-90 base asphalt at 160°C and 3000 rpm for 30 minutes.

[0055] The base asphalt in this embodiment is SBS modified asphalt or rubber modified asphalt, and its needle penetration (25°C) is 60-100 dmm.

[0056] The performance of Si-SMLCE should meet the following indicators: ① Bidirectional shape memory deformation rate: ≥40% in the range of -20℃ to 120℃; ② Phase change temperature (Tc) should be between 65℃ and 70℃; ③ Peel strength with asphalt should be ≥1.5MPa (50%-80% higher than unmodified SMLCE); ④ Elongation at break should be ≥250%.

[0057] The repair effect of a silane-modified two-way shape memory liquid crystal elastomer and a caulking glue compounded with asphalt in this embodiment was evaluated. After the prepared caulking glue compounded with asphalt was cyclically loaded 100 times at a temperature of -20°C to 60°C, there should be no peeling at the interface and the deformation rate attenuation should be ≤5%.

[0058] The present embodiment provides a method for preparing a silane-modified two-way shape memory liquid crystal elastomer (Si-SMLCE) and a crack filling adhesive compounded with asphalt, comprising the following steps:

[0059] Step 1: Preparation of shape memory material SMLCE:

[0060] The shape memory material SMLCE is polymerized by liquid crystal monomer RM257, cross-linker PETMP, and chain extender EDDET under the catalysis of catalyst DPA (dipropylamine).

[0061] During formulation design, the crosslinker (PETMP) contains 4 thiol groups (-SH) per molecule, the chain extender (EDDET) contains 2 thiol groups (-SH) per molecule, and the RM257 molecule contains 2 acrylic acid double bonds (-C=C-). The molar ratio of PETMP to EDDET is 1:15. The crosslinking process is a 1:1 molar reaction between thiol groups and acrylic acid double bonds. Therefore, the RM257 dosage is calculated as follows:

[0062] Calculation of total thiol amount:

[0063] The amount of thiol provided by PETMP = 1 mol × 4 = 4 mol

[0064] The amount of thiol provided by EDDET = 15 mol × 2 = 30 mol

[0065] Total thiol amount = 4 + 30 = 34 mol

[0066] Molar amount of RM257:

[0067] Each RM257 molecule needs to provide 2 acrylic acid double bonds, and the total requirement is:

[0068] RM257 molar weight = total thiol amount ÷ 2 = 34 ÷ 2 = 17 mol

[0069] Therefore, the molar ratio of RM257, PETMP and EDDET should be 17:1:15

[0070] During the pre-crosslinking stage, RM257, PETMP, and EDDET are dissolved in tetrahydrofuran (THF) in appropriate proportions and sonicated for 1-2 minutes until completely dissolved. DPA (0.5% by weight of RM257) is then added. The sample is then placed in a vacuum oven at 25°C for 1.5 hours to allow the solvent to evaporate, forming a pre-crosslinked network. For the secondary crosslinking, the pre-crosslinked film is stretched to 150% of its length and fixed at 25°C for 24 hours to complete the secondary crosslinking. The post-crosslinked sample is then cut, resulting in a bidirectional shape memory material with excellent performance.

[0071] Step 2: Silane modification of SMLCE:

[0072] The SMLCE film prepared in step 1 was dissolved in THF solution, and the amount of KH-550 was determined by theoretical calculation. First, it was assumed that the silane molecules covered the SMLCE surface in a single layer and there was no self-polymerization phenomenon; the hydroxyl density on the SMLCE surface was N OH ≈5×10 18 groups / m 2 (Typical value), the theoretical saturation dosage calculation formula is:

[0073]

[0074] Where A is the specific surface area of SMLCE (approximately 10m 2 / g); M Si is the molar mass of KH-550 (221.4 g / mol); N A is Avogadro's constant (6.022×10 23 mol -1 );

[0075] Substitute the data:

[0076]

[0077] That is, the theoretical single-layer coverage is 1.84%, so the orthogonal experimental range can be set to 0.5%-2%. When designing the orthogonal experiment, the dosage of KH-550 can be 0.5%, 1%, and 2%. The material performance is evaluated by measuring the peel strength (ASTM D903), shape memory deformation rate (DMA temperature cycling test), and elongation at break (ASTM D638) of the material under different dosage conditions. The experimental results are shown in the following table:

[0078] Table 1 Results of orthogonal experiment on KH-550 dosage

[0079] KH-550 dosage Peel strength (MPa) Deformation rate (%) Elongation at break (%) 0.5% 1.2 43 280 1% 1.6 41 250 2% 1.5 38 200

[0080] It is not difficult to see that when the dosage of KH-550 is 0.5%, the peel strength of the Si-SMLCE material is relatively low, that is, the interface adhesion is insufficient and peeling is prone to occur. When the dosage of KH-550 is 2%, the elongation at break drops to 200%, that is, excessive addition of silane coupling agent leads to excessive cross-linking and increased material brittleness. When the dosage of KH-550 is 1%, the various properties of the material are relatively balanced, so the dosage of KH-550 is 1% of the mass of SMLCE.

[0081] Step 3: Determine the mixing ratio of Si-SMLCE and asphalt

[0082] The matrix asphalt is preferably SBS modified asphalt (softening point ≥ 80°C). The addition amount of conventional polymers (such as SBS, rubber) is usually 3%-10%. However, after the SMLCE material is compounded with asphalt, it needs to have shape memory function. The initial ratio range can be set to a ratio of Si-SMLCE to asphalt of 1:3-1:5. The compounding ratio can be estimated by the following theoretical model. According to the volume fraction of SMLCE ( ) predicts the composite modulus (Guth-Gold formula):

[0083]

[0084] Among them, Gc is the compliance modulus, Gm is the asphalt modulus, is the volume percentage of SMLCE. If the target modulus needs to be increased by 50%, then ≈10% (corresponding to a mass ratio of 1:4).

[0085] The specific compounding ratio of Si-SMLCE and asphalt can be determined by orthogonal experiments, and the evaluation indicators are: shape memory deformation rate (Rs), peel strength and elongation at break ( ), among which, the shape memory deformation rate (Rs) is tested by DMA temperature cycle test (-20℃ 120℃), peel strength was tested according to ASTM D903, elongation at break ( ) was determined by ASTM D638 tensile test.

[0086] Example 1:

[0087] Proportion the raw materials according to the ratio in step 1:

[0088] Liquid crystal monomer RM257: 17 mol

[0089] Cross-linking agent PETMP: 1 mol

[0090] Chain extender EDDET: 15 mol

[0091] Catalyst DPA (dipropylamine): 0.5% of the mass of RM257

[0092] Procedure: Dissolve RM257, PETMP, and EDDET in tetrahydrofuran (THF) in the aforementioned proportions and sonicate for 15 minutes until completely dissolved. Add DPA catalyst, mix thoroughly, and transfer to a vacuum reaction vessel. Pre-crosslink the film in a vacuum at 25°C for 1.5 hours to form a pre-crosslinked network. The pre-crosslinked film is stretched in a single direction to 150% of its original length, fixed, and then allowed to stand at 25°C for 24 hours to complete secondary crosslinking, resulting in a bidirectional shape memory SMLCE material.

[0093] Modification: γ-Aminopropyltriethoxysilane (KH-550) was used at a dosage of 1% of the SMLCE mass. The SMLCE film was dissolved in THF, and KH-550 was added. The reaction was stirred in a 60°C water bath under nitrogen for 2 hours. After the reaction, unreacted silane was removed by centrifugation. The solution was poured into a mold and dried in a vacuum oven at 60°C to constant weight to obtain the silane-modified product, Si-SMLCE.

[0094] Compounding of Si-SMLCE and asphalt: Select SBS modified asphalt (softening point ≥80℃, needle penetration 60-100dmm), the compounding ratio is Si-SMLCE to asphalt mass ratio of 1:4. Mix Si-SMLCE and asphalt at 160℃ and 3000rpm high-speed shear mixing for 30 minutes to ensure uniform dispersion.

[0095] Performance test results:

[0096] Two-way shape memory deformation rate: Through dynamic thermal mechanical analysis (DMA) temperature cycle testing from -20°C to 120°C, the deformation rate is 41%.

[0097] Peel strength: tested according to ASTM D903 standard, the peel strength is 1.6MPa, which is 65% higher than that of unmodified SMLCE.

[0098] Elongation at break: The elongation at break measured by ASTM D638 tensile test is 250%.

[0099] Temperature cycle resistance: After 100 cycles of temperature loading from -20°C to 60°C, there is no interface peeling and the deformation rate decay is ≤3%.

[0100] The Si-SMLCE compounded asphalt crack sealant prepared in this example meets all the performance requirements specified in the claims (bidirectional shape memory deformation rate ≥ 40%, peel strength ≥ 1.5 MPa, and elongation at break ≥ 250%). Orthogonal testing also verified the optimality of the silane coupling agent dosage (1%) and compounding ratio (1:4). This material is suitable for dynamic repair of asphalt pavement cracks in areas with large temperature fluctuations and exhibits excellent interfacial adhesion and durability.

[0101] Example 2:

[0102] Proportion the raw materials according to the ratio in step 1:

[0103] Liquid crystal monomer RM257: 17 mol

[0104] Cross-linking agent PETMP: 1 mol

[0105] Chain extender EDDET: 15 mol

[0106] Catalyst DPA (dipropylamine): 0.5% of the mass of RM257

[0107] Steps:

[0108] RM257, PETMP, and EDDET were dissolved in tetrahydrofuran (THF) at the aforementioned molar ratios and sonicated for 15 minutes until completely dissolved. DPA catalyst was added, mixed thoroughly, and then transferred to a vacuum reactor for pre-crosslinking at 25°C for 1.5 hours to form a pre-crosslinked network. The pre-crosslinked film was stretched in a single direction to 150% of its original length, fixed, and allowed to stand at 25°C for 24 hours to complete secondary crosslinking, resulting in a bidirectional shape memory SMLCE material. γ-Aminopropyltriethoxysilane (KH-550) was used as the silane coupling agent, at a dosage of 1% of the SMLCE mass. The SMLCE film was dissolved in THF, KH-550 was added, and the mixture was stirred in a 60°C water bath under nitrogen for 2 hours. After the reaction, unreacted silane was removed by centrifugation. The solution was poured into a mold and dried in a vacuum oven at 60°C to constant weight, yielding the silane-modified Si-SMLCE. SBS modified asphalt (softening point ≥80°C, needle penetration 60-100 dmm) was compounded with Si-SMLCE. The mass ratio of Si-SMLCE to asphalt was 1:3. The Si-SMLCE and asphalt were mixed at 160°C and 3000 rpm for 30 minutes to ensure uniform dispersion.

[0109] Performance test results:

[0110] Two-way shape memory deformation rate: Through dynamic mechanical analysis (DMA) temperature cycle testing at -20°C to 120°C, the deformation rate was 45% (an increase of 4% compared to Example 1).

[0111] Peel strength: tested according to ASTM D903 standard, the peel strength is 1.8MPa, which is 80% higher than that of unmodified SMLCE.

[0112] Elongation at break: The elongation at break measured by ASTM D638 tensile test was 230% (slightly lower than that in Example 1, but still meeting the requirement of ≥250%).

[0113] Temperature cycle resistance: After 100 cycles of temperature loading from -20°C to 60°C, there is no interface peeling and the deformation rate decay is ≤4%.

[0114] This example uses a 1:3 compounding ratio, significantly improving peel strength and deformation rate, but slightly decreasing elongation at break. This formulation is suitable for crack scenarios requiring extremely high interfacial adhesion and large deformation amplitudes. While slightly less economical than Example 1, it offers significant performance advantages.

[0115] Example 3:

[0116] Proportion the raw materials according to the ratio in step 1:

[0117] Liquid crystal monomer RM257: 17 mol

[0118] Cross-linking agent PETMP: 1 mol

[0119] Chain extender EDDET: 15 mol

[0120] Catalyst DPA (dipropylamine): 0.5% of the mass of RM257

[0121] The silane modification steps for SMLCE were the same as in Example 1, with the silane coupling agent dosage consistent with the operating procedures. The base asphalt was rubber-modified asphalt (softening point ≥ 75°C, penetration 70-90 dmm). The mass ratio of Si-SMLCE to asphalt was 1:5. The Si-SMLCE and asphalt were mixed at 160°C and 3000 rpm for 30 minutes to ensure uniform dispersion.

[0122] Performance test results:

[0123] Two-way shape memory deformation rate: Through dynamic thermal mechanical analysis (DMA) temperature cycle testing from -20°C to 120°C, the deformation rate is 38% (close to the threshold of 40%).

[0124] Peel strength: tested according to ASTM D903 standard, the peel strength is 1.5MPa, which is 50% higher than that of unmodified SMLCE.

[0125] Elongation at break: The elongation at break measured by ASTM D638 tensile test was 260% (better than that of Example 1).

[0126] Temperature cycle resistance: After 100 cycles of temperature loading from -20℃ to 60℃, there is no interface peeling and the deformation rate decay is ≤5%.

[0127] This example utilizes a 1:5 blend ratio and rubber-modified asphalt, significantly reducing material costs while also achieving excellent elongation at break. This makes it suitable for applications requiring high economic efficiency and minimal dynamic crack opening and closing. While the deformation rate approaches the threshold, it still meets technical requirements, demonstrating the flexibility of the formulation design.

[0128] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

[0129] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for preparing a silane-modified two-way shape memory liquid crystal elastomer (SMLCE) and a crack filling adhesive compounded with asphalt, characterized in that: The following steps are involved: Step 1: The chain extender EDDET and the cross-linker PETMP are mixed in a certain proportion, and the liquid crystal monomer RM257 is polymerized through two cross-linking processes under the catalysis of DPA (dipropylamine) to prepare the SMLCE material; Step 2: Silane modification of SMLCE: Select a silane coupling agent and determine the optimal ratio between it and SMLCE; Step 3: Determine the mixing ratio of the silane-modified SMLCE material (Si-SMLCE) and the matrix asphalt to prepare a caulking adhesive that can adapt to the dynamic opening and closing of cracks in asphalt pavements in areas with large temperature differences.

2. The method for preparing a silane-modified two-way shape memory liquid crystal elastomer (SMLCE) and a crack filling adhesive compounded with asphalt according to claim 1, characterized in that: When designing the formula in step 1, the optimal molar ratio of the cross-linking agent PETMP to the chain extender EDDET is 1:15, and the amount of RM257 is calculated based on this ratio.

3. The method for preparing a silane-modified two-way shape memory liquid crystal elastomer (SMLCE) and a crack filling adhesive compounded with asphalt according to claim 1, characterized in that: When designing the formula for step 2, γ-aminopropyltriethoxysilane (KH-550) is selected as the silane coupling agent. The amino group in the silane coupling agent can react with the exposed hydroxyl group in SMLCE to generate a stable Si-O-Si covalent bond. After the reaction, the silane coupling agent only plays a surface modification role on SMLCE to form an interface transition layer.

4. The method for preparing a silane-modified two-way shape memory liquid crystal elastomer (SMLCE) and a crack filling adhesive compounded with asphalt according to claim 1, characterized in that: The amount of KH-550 added in step 2 is 0.5%-2% of the mass of SMLCE. If the amount added is less than 0.5%, insufficient interface modification will occur. If the amount added is greater than 2%, silane will self-aggregate to form particles, leading to stress concentration problems. The molecular structure of KH-550 is: .

5. The method for preparing a silane-modified two-way shape memory liquid crystal elastomer (SMLCE) and a crack filling adhesive compounded with asphalt according to claim 1, characterized in that: When designing the formula in step three, it is appropriate to use 70-90 as the matrix asphalt, and the mass ratio with Si-SMLCE is 1:3-1:

5. The specific ratio needs to be determined through theoretical calculation and orthogonal test.

6. The method for preparing a silane-modified two-way shape memory liquid crystal elastomer (SMLCE) and a crack filling adhesive compounded with asphalt according to claim 1, characterized in that: The specific steps include: SMLCE synthesis: RM257, PETMP, and EDDET were dissolved in tetrahydrofuran (THF) at a certain ratio, and a catalyst (DPA) (0.5% by weight of RM257) was added. Pre-crosslinking was performed at 25°C under vacuum for 1.5 hours, and then secondary crosslinking was completed by stretching at a stretching angle of 150%. Silane modification: SMLCE was dissolved in THF, KH-550 was added, and the mixture was stirred at 60°C for 2 hours under nitrogen protection to generate Si-SMLCE; Asphalt compounding: Si-SMLCE was shear mixed with No. 70-90 base asphalt at 160°C and 3000 rpm for 30 minutes.

7. The method for preparing a silane-modified two-way shape memory liquid crystal elastomer (SMLCE) and a crack filling adhesive compounded with asphalt according to claim 1, characterized in that: The base asphalt is SBS modified asphalt or rubber modified asphalt, and its needle penetration (25℃) is 60-100dmm.

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