Modeling method of molecular dynamics model of road single-component polyurethane adhesive

Abstract

The invention relates to the field of polyurethane molecular models and road engineering materials, in particular to a modeling method of a road single-component polyurethane adhesive molecular dynamics model. The modeling method of the molecular dynamics model of the road single-component polyurethane adhesive comprises the following steps: setting reaction functional groups according to determined reaction raw materials of polyurethane, calculating the proportion of reaction raw material molecules, and then placing the reaction raw material molecules in the same system according to the proportion, so as to obtain the molecular dynamics model of the road single-component polyurethane adhesive. And setting a preset crosslinking reaction degree and carrying out molecular crosslinking reaction kinetic simulation. According to the method, the curing and crosslinking degree can be accurately and quantitatively evaluated, the curing and crosslinking form of molecules is determined, and a key technical support is provided for deep understanding of material performance, formula optimization and research and development of novel high-performance road materials.

Description

Technical Field

[0001] This invention relates to the fields of polyurethane molecular models and road engineering materials, and particularly to a modeling method for a molecular dynamics model of a single-component polyurethane adhesive for road use. Background Technology

[0002] Polyurethane is one of the key synthetic materials being developed globally. Its superior properties, including high adhesion, high elasticity, and resistance to chemical corrosion, have garnered widespread attention. Its chemical composition, molecular structure, and macroscopic properties have highly adjustable thresholds, allowing for wide application in various engineering fields as elastomers, foams, adhesives, coatings, and sealants. It not only possesses excellent mechanical, adhesive, water-resistant, and chemically stable properties but also boasts advantages such as stable performance, low energy consumption, and suitability for room-temperature mixing. Therefore, the versatility of polyurethane material types and its superior performance offer greater potential for future promotion. Polyurethane mixtures, using polyurethane adhesives as binders to completely replace asphalt, are road construction materials formed by mixing with aggregates at room temperature. Compared to asphalt pavements, they offer significant advantages in terms of greenness, low carbon footprint, and high performance. This technology represents a disruptive technological innovation in my country's road engineering field in recent years and is expected to revolutionize the century-old pavement material technology system.

[0003] However, the interfacial interaction between polyurethane adhesives and aggregates is complex. Their road performance (such as strength development, modulus, fatigue life, weather resistance, and adhesion to aggregates) fundamentally depends on the microscopic cross-linked network structure formed after curing. Traditional experimental methods struggle to reveal the intrinsic reaction mechanisms of polyurethane molecules. To gain a deeper understanding of the "material-structure-performance" relationship, optimize formulation design, and predict the long-term performance of polyurethane, establishing accurate polyurethane molecular models is crucial. The core challenges currently facing the field of molecular modeling for single-component polyurethane for road applications are: inefficient and error-prone initial model construction; a lack of methods for real-time and accurate quantification of cross-linking degree at the molecular simulation level; and the inability to dynamically simulate the complex curing process triggered by moisture, multi-reaction competition, and diffusion control, as well as the resulting cross-linked network with a realistic topological structure. These shortcomings severely restrict the use of molecular simulation technology to gain a deeper understanding of the microscopic mechanisms of polyurethane mixtures and accelerate the design and optimization of high-performance environmentally friendly pavement materials.

[0004] The properties of polyurethane materials are highly dependent on their microscopic molecular structure, especially the morphology of the crosslinking network. Current technologies struggle to directly and accurately determine and establish a polyurethane molecular model, primarily due to the following problems: 1) Difficulty in directly drawing a polyurethane molecular model. Polyurethane is typically composed of complex components such as isocyanates, polyols, and water molecules. The molecular chain structure and potential random crosslinking points make manually constructing an initial model extremely tedious, time-consuming, and prone to errors. 2) Difficulty in quantitatively and accurately assessing the degree of crosslinking. Traditional experimental methods have significant errors, and simple model statistics often fail to provide accurate, real-time microscopic quantitative indicators such as crosslinking density, crosslinking point distribution, and network defects at the molecular simulation level. 3) Difficulty in determining the curing crosslinking form of the molecule. Polyurethane curing is a dynamic, stochastic process involving multiple competing reactions (such as the reaction of isocyanates with hydroxyl groups, water, urethanes, urea groups, etc.). The functionality, proportion (R-value), catalyst, and temperature of the reactants collectively determine the final crosslinking network structure. Static models cannot reflect this dynamic evolution process, making it difficult to accurately predict and construct a truly representative crosslinking network model. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a modeling method for the molecular dynamics of single-component polyurethane adhesives for road applications. This method enables precise quantitative assessment of the degree of curing and crosslinking, determining the curing and crosslinking forms of molecules, and providing crucial technical support for a deeper understanding of material properties, formulation optimization, and the development of novel high-performance road materials.

[0006] Firstly, the modeling method for the molecular dynamics model of a single-component polyurethane adhesive for road use provided by this invention includes: setting reactive functional groups based on the determined reactant raw materials of polyurethane, calculating the proportion of reactant raw material molecules, placing the reactant raw material molecules in the same system according to the above proportion, pre-setting the degree of crosslinking reaction, and conducting molecular crosslinking reaction dynamics simulation. The modeling method for the single-component polyurethane molecular model for road use provided by this invention, which sets reactive functional groups based on the determined reactant raw materials of polyurethane, calculates the proportion of raw material molecules, places the reactant raw material molecules in the same system according to the proportion, and conducts molecular crosslinking reaction dynamics simulation according to the pre-set degree of crosslinking reaction, can accurately and quantitatively evaluate the degree of curing crosslinking, determine the curing crosslinking form of molecules, and provide key technical support for a deeper understanding of material properties, optimization of formulations, and development of new high-performance road materials.

[0007] According to the present invention, the same system is a virtual three-dimensional space created in a computer for simulation.

[0008] Preferably, the modeling method for the molecular dynamics model of the road-use single-component polyurethane adhesive includes the following steps: 1) Determine the reaction raw materials for polyurethane.

[0009] 2) Determine the reactive functional groups of the reactant molecules and set one or more atoms in the reactive functional groups as reaction sites.

[0010] 3) Set the addition ratio of reaction raw material molecules according to the functional group reaction ratio.

[0011] 4) Place the reactant molecules in the same system according to the added ratio, and conduct molecular cross-linking reaction kinetics simulation according to the preset cross-linking reaction degree.

[0012] Preferably, the reaction raw materials for the polyurethane include isocyanate and polyol.

[0013] Further preferably, the reaction sites set according to the aforementioned functional groups include atoms from the NCO functional group of isocyanates and atoms from the terminal hydroxyl functional groups of polyols. The selected reaction sites facilitate subsequent modeling.

[0014] Further preferably, the reaction sites include N atoms and O atoms.

[0015] Preferably, the preset cross-linking reaction degree is ≥85%, and more preferably 85%~90%.

[0016] Further optimization was carried out by conducting molecular cross-linking reaction kinetic simulation. After reaching the preset degree of cross-linking reaction, the constructed road-use single-component polyurethane molecular model was obtained.

[0017] As a preferred option, the method also includes inputting the number of functional groups involved in the molecular cross-linking reaction into the formula to calculate the degree of cross-linking reaction.

[0018] Further preferably, the formula for calculating the degree of crosslinking reaction is Equation (1): Degree of cross-linking reaction = (NF) 11 -NF 12 ) / NF 11 *100 (1); In the formula, NF 11 Indicates the number of initial reaction sites F1 within the current molecular system; NF 12 This indicates the number of F12 reaction sites after the cross-linking reaction within the current molecular system.

[0019] Secondly, the present invention provides a molecular model of a road-use single-component polyurethane adhesive obtained by a modeling method for the molecular dynamics model of the road-use single-component polyurethane adhesive.

[0020] This invention presents a method for establishing a molecular model of single-component polyurethane for road use. Based on the curing reaction mechanism of polyurethane, this invention addresses the difficulty of directly drawing polyurethane molecular models by proposing a modeling method for easily drawn molecular dynamics models of single-component polyurethane adhesives for road use. Simultaneously, addressing the difficulty in quantitatively and accurately assessing the degree of crosslinking, this invention proposes a method for accurately assessing the degree of crosslinking in polyurethane molecular models. Furthermore, addressing the difficulty in determining the curing crosslinking forms between molecules, this invention proposes a universally applicable method for crosslinking modeling of polyurethane molecular models. This invention first establishes the polyurethane reaction raw materials, such as isocyanate, polyol, and chain extender. Then, it sets the reaction atomic sites, such as R1 for isocyanate functional groups and R2 for polyol functional groups. Subsequently, based on the preset formula molar ratio, a spatially randomly distributed molecular system is automatically generated using a Monte Carlo algorithm to ensure that the initial state of the model conforms to the actual mixing state, and then the crosslinking reaction is carried out to establish a polyurethane crosslinking molecular model. The polyurethane molecular model construction method provided by this invention overcomes the problems of traditional manual initial model construction being extremely cumbersome, time-consuming, and prone to errors. This method can accurately and quantitatively evaluate the degree of curing and crosslinking, determine the curing and crosslinking form of molecules, and accurately predict and construct a crosslinking network model with real representativeness. This provides key technical support for a deeper understanding of material properties, optimization of formulations, and development of new high-performance road materials. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in this 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 some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 Crosslinking degree-simulation time curve provided for embodiments of the present invention.

[0023] Figure 2 A flowchart of the testing method provided in an embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of the molecular structure of 2,4-toluene diisocyanate provided in an embodiment of the present invention.

[0025] Figure 4 This is a schematic diagram of the molecular structure of glycerol provided in an embodiment of the present invention.

[0026] Figure 5 This is a schematic diagram of the water molecule structure provided in an embodiment of the present invention.

[0027] Figure 6 The molecular model before the crosslinking reaction is provided for the embodiments of the present invention.

[0028] Figure 7 The molecular model after the crosslinking reaction is provided for the embodiments of the present invention.

[0029] Figure 8 The density of the polyurethane molecular model provided in the embodiments of the present invention.

[0030] Figure 9 The energy of the polyurethane molecular model provided in the embodiments of the present invention.

[0031] Figure 10 The polyurethane molecular model provided for the embodiments of the present invention.

[0032] Figure 11 The density of the polyurethane molecular model provided in the embodiments of the present invention.

[0033] Figure 12 The energy of the polyurethane molecular model provided in the embodiments of the present invention.

[0034] Figure 13 The polyurethane molecular model provided for the embodiments of the present invention. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0036] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0037] Unless otherwise specified, the techniques or conditions described in the embodiments of this invention shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Devices, instruments, reagents, etc., without specified manufacturers, are all conventional products that can be purchased through legitimate channels. All experimental reagents and raw materials involved are commercially available products, and all reagents are analytical grade products.

[0038] The following embodiments of the present invention provide a modeling method for the molecular dynamics model of a road-use single-component polyurethane adhesive, which is specifically reflected in at least the following aspects: 1) Avoid errors in manual drawing and improve modeling accuracy and efficiency. Manually drawing complex components (such as single-component systems containing latent curing agents) is prone to introducing systematic errors due to functional mismatches, spatial conformational distortions, and proportional deviations. This invention addresses this by parameterizing raw material inputs, allowing isocyanate (NCO), polyol (OH), water molecules, and other components to be input according to the formulation ratio. The Monte Carlo algorithm is then used to automatically generate a spatially randomly distributed initial mixture model, completely avoiding bonding errors and unreasonable conformations caused by manual drawing, thus ensuring the comparability of simulation results.

[0039] 2) Achieve dynamic automatic cross-linking This invention can quantitatively assess the degree of polyurethane crosslinking and curing. Existing technologies struggle to accurately reflect the moisture-triggered, multi-reaction-competitive curing process of road-use polyurethane. This invention utilizes the principles of chemical reaction to drive the process, pre-setting reaction sites, such as: R1-NCO + H2O → R1-urea + CO2; R1-NCO + R3-NH2 → R1-R3-urea; R1-NCO+ urea group → biuret.

[0040] It achieves dynamic bonding simulation, based on the Monte Carlo probability model, calculates the reaction probability of neighboring groups in real time, automatically performs bonding / bond breaking operations, and dynamically updates the molecular structure.

[0041] Based on this, water molecules and temperature parameters can be introduced to regulate the reaction rate, realistically reproducing the curing kinetics in road applications. Simultaneously, it can autonomously generate statistically representative crosslinking networks (including byproducts such as CO2 and biuret crosslinking points), overcoming the limitation of static models in reflecting dynamic curing processes.

[0042] 3) Quantitatively assess the degree of cross-linking Traditional methods struggle to dynamically monitor the curing process of road-use polyurethane at the molecular level, leading to inaccurate predictions of early strength development. This invention achieves a breakthrough through formula (1).

[0043] Degree of cross-linking reaction = (NF) 11 -NF 12 ) / NF 11 *100 (1); In the formula, NF 11 Indicates the number of initial reaction sites F11 in the current molecular system; NF 12 This indicates the number of F12 reaction sites after the cross-linking reaction within the current molecular system.

[0044] Automatically update NF after each reaction step in the Monte Carlo simulation. 12 Values ​​are used to generate crosslinking degree-simulated time curves, such as... Figure 1 As shown.

[0045] Specific embodiments of the present invention, the test methods are as follows: Figure 2 As shown, the process is divided into five steps: determining the polyurethane reactants, setting the reactive functional groups of the molecules, calculating the proportions of various reactant molecules, initiating the molecular cross-linking reaction, reaching the preset degree of cross-linking, and completing the polyurethane molecule modeling. Figure 3-5 The diagram shows the molecular structures of the polyurethane reaction raw materials, including the structures of 2,4-toluene diisocyanate, glycerol, and water molecules. Figure 6 This refers to the initial state of polyurethane reactant molecules in the same system, according to the Monte Carlo principle, i.e., the molecular model before the crosslinking reaction. Figure 7 This is the molecular model after the cross-linking reaction.

[0046] The following embodiments of the present invention provide a modeling method for the molecular dynamics model of a road-use single-component polyurethane adhesive. Starting from the principle of polyurethane curing reaction, the method focuses on the types and proportions of polyurethane raw materials, and quantitatively calculates and analyzes the degree of curing and crosslinking during the polyurethane reaction process. The specific method is as follows: 1) Determine the raw materials for the polyurethane reaction: Taking polyether polyurethane as an example, determine the raw materials such as isocyanate, polyether polyol, and water. Draw the above molecular model in molecular dynamics software, such as HyperChem used in the examples. Based on this, set appropriate charges and force fields for the molecular model and perform geometric optimization.

[0047] 2) Setting the reactive functional groups of molecules: Based on the chemical reaction raw materials, set the reaction sites of molecules such as isocyanate and polyether polyol. Here, taking polyether polyurethane as an example, set the N atom in the isocyanate functional group as the reaction site F1, and set the O in the terminal hydroxyl functional group of the polyether polyol molecule as the reaction site F2.

[0048] 3) Calculate the proportion of reactant molecules: Based on the actual reaction proportion and the functional group reaction proportion, determine the amount of reactant molecules to be added.

[0049] 4) Start the molecular cross-linking reaction: According to the Monte Carlo principle, place the determined raw material molecules in the same system and carry out the molecular cross-linking reaction according to the set cross-linking sites.

[0050] 5) Assess the degree of cross-linking reaction: Substitute the number of reaction sites mentioned above into formula (1) to calculate the degree of curing and crosslinking of the product.

[0051] Degree of cross-linking reaction = (NF) 11 -NF 12 ) / NF 11 *100 (1) In the formula, NF 11Indicates the number of initial reaction sites F11 in the current molecular system; NF 12 This indicates the number of F12 reaction sites after the crosslinking reaction within the current molecular system. Based on the above, the present invention further provides the following specific embodiments.

[0052] Example 1 This embodiment provides a modeling method for the molecular dynamics of a road-use single-component polyurethane adhesive, including: First, determining that the polyurethane reactants are 2,4-toluene diisocyanate and glycerol molecules. Second, drawing molecular models of the two reactants, setting appropriate charges and force fields, and performing geometric optimization. Third, designating the N atom in the NCO functional group of 2,4-toluene diisocyanate as reaction site F1, and the O atom in the terminal hydroxyl functional group of glycerol molecule as reaction site F2. Subsequently, setting the ratio of 2,4-toluene diisocyanate to glycerol molecules to 3:2. Based on this, placing the corresponding number of molecules in the same system, setting the crosslinking reaction degree to 90%, and conducting molecular crosslinking reaction dynamics simulation. Finally, achieving a 90% crosslinking degree completes the construction of the molecular model.

[0053] Model validation: Under real-world conditions, the density of this polyurethane is 1.1 g / cm³. 3 The density simulated in the software is approximately 1.19 g / cm³. 3 ( Figure 8 As shown). Furthermore, by observing the model energy list, it was found that the model energy is stable, indicating that the model has stabilized. Figure 9 (As shown in the figure). Therefore, the calculation results indicate that the model has high reliability and can be used for further research and analysis.

[0054] Example 2 This embodiment provides a modeling method for the molecular dynamics of a road-use single-component polyurethane adhesive, including: First, determining that the polyurethane reactants are diphenylmethane diisocyanate and polypropylene glycol molecules. Second, drawing molecular models of the two reactants, setting appropriate charges and force fields, and performing geometric optimization. Third, designating the N atom in the NCO functional group of diphenylmethane diisocyanate as reaction site F1, and the O atom in the terminal hydroxyl functional group of polypropylene glycol as reaction site F2. Subsequently, setting the ratio of diphenylmethane diisocyanate to polypropylene glycol molecules to 1:1. Based on this, placing the corresponding number of molecules in the same system, setting the crosslinking reaction degree to 85%, and conducting molecular crosslinking reaction dynamics simulation. Finally, achieving a crosslinking degree of 85% completes the construction of the molecular model.

[0055] Model validation: Under real-world conditions, the density of this polyurethane is 1.15 g / cm³. 3 The density simulated in the software is approximately 1.94 g / cm³.3 ( Figure 11 As shown). Furthermore, by observing the model energy list, it was found that the model energy is stable, indicating that the model has stabilized. Figure 12 (As shown in the figure). Therefore, the calculation results indicate that the model has high reliability and can be used for further research and analysis.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A modeling method of a molecular dynamics model of a one-component polyurethane adhesive for road use, characterized by, The method comprises the following steps: 1) determining the reaction raw materials of the polyurethane; 2. The modeling method of the molecular dynamics model of the road use one-component polyurethane adhesive according to claim 1, characterized in that, 2) determining the reaction functional groups of the reaction raw material molecules, and setting one or more atoms in the reaction functional groups as reaction points; 3) setting the addition ratio of the reaction raw material molecules according to the reaction ratio of the functional groups; 4) placing the reaction raw material molecules in the same system according to the addition ratio, and carrying out molecular crosslinking reaction kinetics simulation according to the preset crosslinking reaction degree. The reaction raw materials of the polyurethane include isocyanate and polyol. The reaction points set according to the reaction functional groups include atoms in the NCO functional groups of the isocyanate and atoms in the terminal hydroxyl functional groups of the polyol.

3. The modeling method of the molecular dynamics model of the road-use one-component polyurethane adhesive according to claim 2, characterized in that, The reaction points include N atoms and O atoms.

4. The modeling method of the molecular dynamics model of the road use one-component polyurethane adhesive according to claim 3, characterized in that, The preset crosslinking reaction degree is greater than or equal to 85%.

5. The modeling method of the molecular dynamics model of the one-component polyurethane adhesive for road use according to claim 4, characterized in that, After carrying out the molecular crosslinking reaction kinetics simulation, the road single-component polyurethane molecular model is obtained when the preset crosslinking reaction degree is reached.

6. The modeling method of the molecular dynamics model of the one-component polyurethane adhesive for road use according to any one of claims 1 to 5, characterized in that, The method further comprises inputting the number of functional groups in the molecular crosslinking reaction into a formula to calculate the crosslinking reaction degree.

7. The modeling method of the molecular dynamics model of the one-component polyurethane adhesive for road use according to claim 6, characterized in that, The formula for calculating the crosslinking reaction degree is formula (1):

8. The modeling method of the molecular dynamics model of the one-component polyurethane adhesive for road use according to any one of claims 1 to 7, characterized in that, 10. The road single-component polyurethane molecular model obtained by the modeling method of the road single-component polyurethane adhesive molecular dynamics model according to any one of claims 1-9.

9. The modeling method of the molecular dynamics model of the one-component polyurethane adhesive for road use according to claim 8, characterized in that, ​ Cross-linking reaction degree = (NF 11 -NF 12 ) / NF 11 * 100 (1); In the formula, NF 11 represents the number of initial reaction sites F11 in the current molecular system; NF 12 represents the reaction sites F12 after cross-linking reaction in the current molecular system. ​

Images