Method and device for predicting waterproof performance of polyurethane film

Abstract

The invention discloses a polyurethane film waterproof performance prediction method and device, and the method comprises the steps: building a simplified molecular model based on a polyurethane chain and water molecules; performing molecular dynamics simulation based on the simplified molecular model to obtain a tension acting value; on the basis of the tensile force acting value, calculating through a Jarzynski formula to obtain average work; based on the movement track of the water molecules in molecular dynamics simulation, umbrella-shaped sampling simulation is carried out with the set positions of the water molecules as reaction coordinates, a self-consistent equation is solved through an MBAR strategy, and an equilibrium state free energy surface is obtained; comparing the known experimental waterproof performance data with the average work and the equilibrium state free energy surface respectively, and constructing a set mapping model; and predicting the input to-be-predicted polyurethane film by setting the mapping model, and outputting the waterproof performance prediction of the to-be-predicted polyurethane film. According to the method, the prediction accuracy is improved under the condition of scarcity of experimental data, the experimental quantity is greatly reduced, and the problem that an existing method depends on computing resources and large samples is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer material performance prediction, and in particular to a method and device for predicting the waterproof performance of a polyurethane film. Background Art

[0002] Polyurethane is an organic polymer material formed by the polymerization of oligomeric diols, isocyanates, and chain extenders. Polyurethane materials have a wide range of applications, including textiles, healthcare, construction, and other fields, and their product forms include coatings, films, elastomers, and more. Therefore, it is important to develop polyurethane materials with specific physical and chemical properties. Among these, the waterproof performance of polyurethane materials is a key performance indicator when polyurethane is used as a film or coating material. In the development of new polyurethane materials, if the waterproof performance of a polyurethane material corresponding to a certain raw material can be predicted without conducting experiments, the amount of experiments can be reduced, thereby improving R&D efficiency.

[0003] At present, the existing methods are mainly experimental, computational and data-driven methods. Experimental methods include the synthesis and testing of samples, which consumes a lot of time and cost. At the same time, the amount of experiments that can be performed is limited, and it is difficult to conduct systematic and comprehensive experiments on a large number of monomers, proportions, and combinations of additives. In computational methods, considering computing resources and time, the scale and simulation time for modeling polymer systems are also limited, making it difficult to directly model and simulate real experimental conditions. Therefore, it is difficult to obtain computational results that directly correspond to experimental results through computational methods. On the other hand, data-driven methods have very high requirements for existing data sets. Since data sets need to be obtained through experiments, the data sets must be insufficient. Data-driven methods usually perform poorly when data sets are insufficient.

[0004] Therefore, how to invent a method for predicting the waterproof performance of polyurethane films that can effectively solve the problems existing in the existing technology has become an urgent problem to be solved. Summary of the Invention

[0005] To this end, the present invention provides a method and device for predicting the waterproof performance of polyurethane films. By constructing a small-scale molecular model and integrating it with enhanced sampling molecular dynamics simulation, the microscopic work required for water to penetrate the polyurethane film is converted into a free energy barrier, and a quantitative correlation with the macroscopic waterproof performance is established. This improves the prediction accuracy under conditions of scarce experimental data, greatly reduces the amount of experiments, and solves the problem of existing methods' dependence on computing resources and large samples.

[0006] In order to achieve the above object, the present invention provides the following technical solution: a method for predicting the waterproof performance of a polyurethane film, comprising:

[0007] According to the monomer structures of the polyol, isocyanate and chain extender of the target polyurethane, a polyurethane chain is formed by linking; and based on the polyurethane chain and water molecules, a simplified molecular model is constructed;

[0008] Based on the simplified molecular model, molecular dynamics simulation is performed to obtain the tensile work value;

[0009] Based on the tensile work value, the average work is calculated using the Jarzynski formula;

[0010] Based on the movement trajectory of the water molecules in the molecular dynamics simulation, an umbrella sampling simulation is performed with the set position of the water molecules as the reaction coordinate, and the self-consistent equation is solved by the MBAR strategy to obtain the equilibrium free energy surface;

[0011] Comparing known experimental waterproof performance data with the average work and the equilibrium free energy surface respectively, and constructing a set mapping model;

[0012] The input polyurethane film to be predicted is predicted through the set mapping model, and the waterproof performance prediction of the polyurethane film to be predicted is output.

[0013] As a preferred method for predicting the waterproof performance of a polyurethane film, in the process of performing molecular dynamics simulation based on the simplified molecular model:

[0014] External force is applied to the water molecules to make them penetrate the polyurethane film, and the work done by the tension is obtained by simulation trajectory calculation.

[0015] As a preferred solution of a method for predicting the waterproof performance of a polyurethane film, the calculation formula of the average work is:

[0016] e -βΔF = <e -βW >

[0017] Where β = 1 / k B T(k B is the Boltzmann constant) is the simulation temperature; <…> is the average treatment; W is the work done by the tension; ΔF is the average work; e=2.71828... is the base of the natural logarithm.

[0018] As a preferred method for predicting the waterproof performance of polyurethane films, during the umbrella sampling simulation:

[0019] The set position for sampling the water molecules is:

[0020]

[0021] Where R0 is the initial position of the water molecule; R1 is the current position of the water molecule in the molecular dynamics simulation; (d is the thickness of the polyurethane film in the simulation), that is, the number of windows in the umbrella sampling, which is selected so that the positions of water molecules in two adjacent structures differ by

[0022] As a preferred solution for a method for predicting the waterproof performance of a polyurethane film, the process expression for solving the self-consistent equation using the MBAR strategy is:

[0023]

[0024] Where n j is the sampling number of trajectory j; V i (x jn ) is the bias potential calculated from the bias potential function of trajectory i for structure n in trajectory j; f i is the free energy; k is the trajectory.

[0025] The present invention also provides a device for predicting the waterproof performance of a polyurethane film, based on the above method for predicting the waterproof performance of a polyurethane film, comprising:

[0026] A simplified molecular model building module is used to link the polyol, isocyanate and chain extender monomer structures of the target polyurethane to form a polyurethane chain; and to build a simplified molecular model based on the polyurethane chain and water molecules;

[0027] A molecular dynamics simulation module, configured to perform molecular dynamics simulation based on the simplified molecular model to obtain a tensile work value;

[0028] an average work calculation module, configured to calculate the average work based on the pulling work value using the Jarzynski formula;

[0029] An equilibrium free energy surface acquisition module is used to perform an umbrella sampling simulation based on the movement trajectory of the water molecules in the molecular dynamics simulation, with the set position of the water molecules as the reaction coordinate, and solve the self-consistent equation through the MBAR strategy to obtain the equilibrium free energy surface;

[0030] A setting mapping model construction module is used to compare known experimental waterproof performance data with the average work and the equilibrium free energy surface respectively to construct a setting mapping model;

[0031] The waterproof performance prediction module is used to predict the input polyurethane film to be predicted through the set mapping model and output the waterproof performance prediction of the polyurethane film to be predicted.

[0032] As a preferred embodiment of a device for predicting the waterproof performance of a polyurethane film, in the simplified molecular model construction module, during the molecular dynamics simulation based on the simplified molecular model:

[0033] External force is applied to the water molecules to make them penetrate the polyurethane film, and the work done by the tension is obtained by simulation trajectory calculation.

[0034] As a preferred solution of a polyurethane film waterproof performance prediction device, in the average work calculation module, the calculation formula of the average work is:

[0035] e -βΔF = <e -βW >

[0036] Where β = 1 / k B T(k B is the Boltzmann constant) is the simulation temperature; <…> is the average treatment; W is the work done by the tension; ΔF is the average work; e=2.71828... is the base of the natural logarithm.

[0037] As a preferred embodiment of a device for predicting the waterproof performance of a polyurethane film, in the equilibrium free energy surface acquisition module, during the umbrella sampling simulation:

[0038] The set position for sampling the water molecules is:

[0039]

[0040] Where R0 is the initial position of the water molecule; R1 is the current position of the water molecule in the molecular dynamics simulation; (d is the thickness of the polyurethane film in the simulation), that is, the number of windows in the umbrella sampling, which is selected so that the positions of water molecules in two adjacent structures differ by As a preferred solution of a device for predicting the waterproof performance of a polyurethane film, in the equilibrium free energy surface acquisition module, the process expression for solving the self-consistent equation by the MBAR strategy is:

[0041]

[0042] Where n j is the sampling number of trajectory j; V i (x jn ) is the bias potential calculated from the bias potential function of trajectory i for structure n in trajectory j; f i is the free energy; k is the trajectory.

[0043] The present invention has the following advantages: Based on the monomeric structures of the target polyurethane, polyol, isocyanate, and chain extender, a polyurethane chain is formed; a simplified molecular model is constructed based on the polyurethane chain and water molecules; a molecular dynamics simulation is performed based on the simplified molecular model to obtain a tensile work value; and based on the tensile work value, the average work is calculated using the Jarzynski formula; an umbrella sampling simulation is performed based on the movement trajectory of the water molecules in the molecular dynamics simulation, with the set positions of the water molecules as reaction coordinates, and the self-consistent equation is solved using the MBAR strategy to obtain an equilibrium free energy surface; known experimental waterproof performance data is compared with the average work and the equilibrium free energy surface to construct a set mapping model; the set mapping model is used to predict the waterproof performance of the input polyurethane film to be predicted, and a prediction of the waterproof performance of the polyurethane film to be predicted is output. The present invention does not directly establish a simulation system based on actual experimental conditions, nor does it directly calculate the experimentally measured waterproof performance. Instead, the present invention establishes a smaller-scale physical model based on experimental conditions; and based on the experimental measurement scheme, a corresponding simulation scheme is customized to calculate properties related to the experimental measurement results. Based on such simulation, it is possible to make qualitative or quantitative predictions of the experimental results, provided that the scale and simulation time of the simulation are within an acceptable range, thereby guiding further experiments. Compared to the data-driven method, the results obtained by simulation in the present invention have physical meaning, and the simulation results can be explained by existing knowledge. Therefore, the results obtained using the present invention have the ability to extrapolate beyond the existing experimental results, thereby still having predictive capabilities when the experimental results are scarce. The present invention uses an enhanced sampling method in molecular simulation, and for processes that are difficult to sample directly, a bias potential is used for forced sampling. Thereafter, a statistical mechanics method is used to restore the measurement results without bias, thereby reducing the amount of computation required for molecular simulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are merely exemplary, and those skilled in the art can, without inventive effort, derive other implementation drawings based on the provided drawings.

[0045] The structures, proportions, sizes, etc. illustrated in this specification are intended solely to complement the contents disclosed herein and to facilitate understanding and reading by persons skilled in the art. They are not intended to limit the conditions under which the present invention may be implemented and therefore have no substantive technical significance. Any structural modifications, changes in proportions, or adjustments in sizes, without affecting the efficacy and objectives of the present invention, shall remain within the scope of the technical contents disclosed herein.

[0046] Figure 1 This is a schematic flow chart of a method for predicting the waterproof performance of a polyurethane film provided in Example 1 of the present invention;

[0047] Figure 2 This is a schematic diagram of a specific implementation process of a method for predicting the waterproof performance of a polyurethane film provided in Example 1 of the present invention;

[0048] Figure 3 This is a schematic diagram of monomers used in a possible embodiment of the polyurethane polymer provided in Example 1 of the present invention;

[0049] Figure 4 This is a schematic structural diagram of multiple polyurethane chains in a possible embodiment provided in Example 1 of the present invention;

[0050] Figure 5 This is a schematic diagram of a tension work curve in a possible embodiment provided in Example 1 of the present invention;

[0051] Figure 6 This is a schematic diagram of the architecture of a device for predicting the waterproof performance of a polyurethane film provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0052] The following describes the implementation of the present invention using specific embodiments. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. Obviously, the embodiments described are only a portion of the present invention, not all of it. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0053] Example 1

[0054] See also Figure 1 and Figure 2 Embodiment 1 of the present invention provides a method for predicting the waterproof performance of a polyurethane film, comprising the following steps:

[0055] S1. Linking the polyol, isocyanate, and chain extender monomer structures of the target polyurethane to form a polyurethane chain; and constructing a simplified molecular model based on the polyurethane chain and water molecules;

[0056] S2. performing molecular dynamics simulation based on the simplified molecular model to obtain a tensile work value;

[0057] S3. Calculating the average work based on the pulling force using the Jarzynski formula;

[0058] S4. Based on the movement trajectory of the water molecules in the molecular dynamics simulation, the set position of the water molecules is used as the reaction coordinate, and an umbrella sampling simulation is performed, and the self-consistent equation is solved by the MBAR strategy to obtain the equilibrium free energy surface;

[0059] S5. Comparing the known experimental waterproof performance data with the average work and the equilibrium free energy surface, respectively, to construct a set mapping model;

[0060] S6. Predicting the input polyurethane film to be predicted by using the set mapping model, and outputting a prediction of the waterproof performance of the polyurethane film to be predicted.

[0061] In this embodiment, in step S1, polyol, isocyanate and chain extender monomer structures of the target polyurethane are linked to form a polyurethane chain; based on the polyurethane chain and water molecules, a simplified molecular model is constructed;

[0062] Specifically, based on the chemical structure of the polyol, isocyanate and chain extender monomers of the target polyurethane, a polyurethane backbone with repeating units of "-(polyol-isocyanate-chain extender-isocyanate)-" is formed through covalent bonds; then, a molecular assembly tool (such as Packmol) is used to construct a simplified system containing 5-10 polyurethane chains and water molecules. After repeated annealing and relaxation under the NPT ensemble until the density is stable, a computable molecular model is formed with a scale much smaller than the actual experiment (film thickness 5-15nm), breaking through the resource limitations of full-scale simulation.

[0063] In this example, the chain length and number of polyurethanes that can be included in the simulation are estimated based on existing experimental data, the data required for the experiment, and the available computing resources and time. Since the present invention does not aim to directly calculate the actual experimental results, the length and number of polyurethanes and the simulation conditions do not need to be the same as the experimental settings.

[0064] In this embodiment, in step S2, a molecular dynamics simulation is performed based on the simplified molecular model to obtain a tensile work value;

[0065] Specifically, a series of molecular dynamics simulations were performed on the polyurethane system, extracting various thermodynamic and kinetic properties from the simulation results that could be relevant to the experimental measurements. To determine the waterproofness of the polyurethane film—that is, to test whether water molecules can pass through it—a simulation of water molecules passing through the polyurethane film was conducted based on knowledge of polymer physics and nonequilibrium statistical mechanics. Based on this simplified molecular model, enhanced sampling molecular dynamics simulations were performed: a linearly increasing external force of 0.05-5nN was applied to the water molecules to force them to penetrate the polyurethane film. The work W done by the tension on the water molecules was recorded for each stretching trajectory. This yielded multiple sets of fundamental physical quantities from the nonequilibrium process, which served as an alternative to mechanical measurements in actual waterproofing experiments.

[0066] In this embodiment, in step S3, the average work is calculated by the Jarzynski formula based on the work value of the pulling force;

[0067] Specifically, the work done by the pulling force W is substituted into the Jarzynski equation, and the apparent free energy change ΔF, i.e., the average work, is calculated by the exponentially weighted average of the non-equilibrium work; this realizes the physical conversion from kinetic quantities to thermodynamic quantities, and captures the energy barrier characteristics of the water penetration process.

[0068] The calculation formula of the average power is:

[0069] e -βΔF = <e -βW >

[0070] Where β = 1 / k B T(k B is the Boltzmann constant) is the simulation temperature; <…> is the average treatment; W is the work done by the tension; ΔF is the average work; e=2.71828... is the base of the natural logarithm.

[0071] Theoretically, the Jarzynski formula obtains the equilibrium free energy surface when water passes through the polyurethane membrane. However, due to the limitations of simulation conditions, it can be considered that the final ΔF includes both thermodynamic and kinetic properties.

[0072] In this embodiment, in step S4, based on the movement trajectory of the water molecules in the molecular dynamics simulation, the set position of the water molecules is used as the reaction coordinate, and an umbrella sampling simulation is performed, and the self-consistent equation is solved by the MBAR strategy to obtain the equilibrium free energy surface;

[0073] Specifically, the movement trajectory of water molecules in the molecular dynamics simulation in step S2 is reused, and the water molecule penetration path is used as the reaction coordinate. More than 20 sampling points are selected in the range of R0 to R1 for umbrella sampling; further, the self-consistent equation is solved through the MBAR strategy to eliminate the influence of the bias potential and output a high-precision equilibrium free energy surface.

[0074] In the process of umbrella sampling, assuming that water is pulled from position R0 to position R1 in the previous simulation trajectory, the sampling position of the water molecules in the molecular dynamics simulation is:

[0075]

[0076] Where R0 is the initial position of the water molecule; R1 is the current position of the water molecule in the molecular dynamics simulation; (d is the thickness of the polyurethane film in the simulation), that is, the number of windows in the umbrella sampling, which is selected so that the positions of water molecules in two adjacent structures differ by

[0077] In this embodiment, the process expression for solving the self-consistent equation by the MBAR strategy is:

[0078]

[0079] Where n j is the sampling number of trajectory j; V i (x jn ) is the bias potential calculated from the bias potential function of trajectory i for structure n in trajectory j; f i is the free energy; k is the trajectory.

[0080] In this embodiment, in step S5, the known experimental waterproof performance data is compared with the average work and the equilibrium free energy surface respectively to construct a set mapping model;

[0081] Specifically, the average work ΔF obtained in step S3 was correlated with the equilibrium free energy surface obtained in step S4, and the resulting energy barrier height was compared with the experimental waterproof performance (such as contact angle and water vapor permeability) of known polyurethane formulations. Based on a presumed positive correlation (e.g., a work difference of 0.078 corresponds to "good performance"), a quantitative mapping model between the free energy barrier and the waterproof grade was constructed to establish a physical benchmark for the prediction.

[0082] In this example, the larger the energy barrier on the free energy surface, the more difficult it is for water molecules to pass through the polyurethane. If the correlation between the calculation results and the experimental results is good, a modeling calculation process for predicting experimental results through molecular dynamics simulation is obtained. If the correlation is not good, such as Figure 2 As shown, the polyurethane modeling, force field, or simulation process needs to be adjusted.

[0083] In this embodiment, in step S6, the input polyurethane film to be predicted is predicted by using the set mapping model, and a prediction of the waterproof performance of the polyurethane film to be predicted is output.

[0084] Specifically, the mapping model of step S5 is called, the new monomer structure is input, and the process of steps S1-S4 is repeated; by comparing the relative free energy barriers of the new formula and the benchmark formula, the predicted level of waterproof performance is directly output to guide the experimental priority sorting.

[0085] In this example, this mapping model can be used to predict the properties of polyurethane films beyond existing experimental results, thereby guiding experiments. Because simulation results may be dependent on detailed settings in the polyurethane modeling or simulation, such as chain length, simulation sampling duration, and heat bath settings, the calculated results for different polyurethanes only need to be compared relative to each other; their absolute values ​​are meaningless. When calculating the properties of a new polyurethane film, the exact same modeling and simulation methods must be used; otherwise, the calculated results for different polyurethane films cannot be compared.

[0086] In a possible embodiment, an example of predicting the waterproof performance of a polyurethane film is provided as follows:

[0087] T1. Use monomers to link polymer chains according to the polyurethane structure to be calculated. For example, the polyurethane to be simulated here is composed of polyester polyol, isocyanate and chain extender, such as Figure 3 As shown. RDKit, Gaussian, Amber and other software were used to model monomers and single polyurethanes and set the force field. The monomer linking method is -(polycarbonate polyol-isocyanate-butanediol-isocyanate)-. On this basis, software such as PackMol was used to establish a simulation system consisting of multiple chains, and the simulation system was relaxed by repeated annealing under the NPT ensemble to prepare a structure that can be used for molecular simulation, such as Figure 4 Molecular simulation and subsequent trajectory analysis mainly use software or packages such as amber, gromacs, plumed, mdtraj, scikit-learn, WHAM, and mbar.

[0088] T2. Based on the properties to be measured in the experiment, a series of equilibrium, non-equilibrium, and enhanced sampling simulations are performed on the simulation system, and quantities related to the experimentally measured properties are extracted from the simulation results. Here, a simulation of water molecules passing through polyurethane is performed to calculate the work done by the tension. The tension-work curve is as follows: Figure 5 shown.

[0089] T3. It is necessary to perform such simulations multiple times and calculate the average work using the Jarzynski formula. At the same time, the density and other properties of the polyurethane in the simulation are calculated. The results show that the density in the simulation is within the range of the usual polymer density of 1000-1200 kg / m 3 The range of the water flow through the polyurethane is within the range of the original trajectory, indicating that the simulation of polyurethane is reasonable. In addition, the free energy surface of water passing through the polyurethane is obtained by performing umbrella sampling simulation starting from the existing trajectory.

[0090] T4. Check the correlation between simulated quantities and experimental measurements. Compare the simulation results with existing experimental results to identify quantities in the simulation that correlate with the experimental results. After comparing the experimental results with the existing experimental results, we found that the quantity "work done by the tensile force per nanometer of polyurethane film in the simulation" correlates with the experimental results and can be used to characterize the difficulty of water passing through the polyurethane film, as shown in Table 1:

[0091]

[0092] Table 1 Difficulty of water passing through polyurethane membrane

[0093] The simulation results shown in Table 1 are relative values ​​compared with monomer No. 1, and the measured value of monomer No. 1 is set to 0. As can be seen from Table 1, the greater the work done by the tension in the simulation, the better the waterproof performance of the corresponding polyurethane.

[0094] Because it doesn’t go through a complex machine learning process, this correlation is interpretable and consistent with existing knowledge. Ultimately, a computational process for predicting experimental results from molecular dynamics simulations can be derived, which can be used to make further performance predictions.

[0095] T5. Input a new polyurethane monomer. After modeling and calculating the above simulation process, the calculation results of the waterproof performance can be given, thereby predicting the experimental results and guiding further experiments. The simulation results are shown in Table 2:

[0096]

[0097] Table 2 Simulation results for new monomers

[0098] According to the results in Table 2, it can be concluded that the polyurethanes corresponding to monomers No. 7, No. 8, and No. 10 have better performance, which can be verified by subsequent experiments.

[0099] In summary, the present invention forms polyurethane chains based on the monomeric structures of the target polyurethane, including polyol, isocyanate, and chain extender. A simplified molecular model is constructed based on the polyurethane chains and water molecules. Molecular dynamics simulations are performed based on the simplified molecular model to obtain tensile work values. Based on the tensile work values, the average work is calculated using the Jarzynski equation. Using the simulation trajectory of the molecular dynamics simulation as a basis and the positions of the water molecules as reaction coordinates, umbrella sampling simulations are performed, and the self-consistent equation is solved using the MBAR strategy to obtain an equilibrium free energy surface. Known experimental waterproof performance data is compared with the average work and the equilibrium free energy surface to construct a set mapping model. The set mapping model is used to predict the waterproof performance of the input polyurethane film to be predicted, outputting a prediction of the waterproof performance of the polyurethane film to be predicted. The present invention does not directly establish a simulation system based on actual experimental conditions, nor does it directly calculate experimentally measured waterproof performance. Instead, the present invention establishes a smaller-scale physical model based on experimental conditions. Based on the experimental measurement scheme, a corresponding simulation scheme is customized to calculate properties related to the experimental measurement results. Based on such simulation, it is possible to make qualitative or quantitative predictions of the experimental results, provided that the scale and simulation time of the simulation are within an acceptable range, thereby guiding further experiments. Compared to the data-driven method, the results obtained by simulation in the present invention have physical meaning, and the simulation results can be explained by existing knowledge. Therefore, the results obtained using the present invention have the ability to extrapolate beyond the existing experimental results, thereby still having predictive capabilities when the experimental results are scarce. The present invention uses an enhanced sampling method in molecular simulation, and for processes that are difficult to sample directly, a bias potential is used for forced sampling. Thereafter, a statistical mechanics method is used to restore the measurement results without bias, thereby reducing the amount of computation required for molecular simulation.

[0100] It should be noted that the method of the embodiments of the present disclosure can be performed by a single device, such as a computer or server. The method of the embodiments of the present disclosure can also be applied in a distributed scenario, where multiple devices cooperate to perform the method. In such a distributed scenario, one of the multiple devices may only perform one or more steps of the method of the embodiments of the present disclosure, and the multiple devices will interact with each other to complete the method.

[0101] It should be noted that the above description is limited to some embodiments of the present disclosure. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in an order different from that described in the above embodiments and still achieve the desired results. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0102] Example 2

[0103] See also Figure 6 Embodiment 2 of the present invention further provides a device for predicting the waterproof performance of a polyurethane film, comprising:

[0104] Simplified molecular model construction module 001 is used to link the polyol, isocyanate and chain extender monomer structures of the target polyurethane to form a polyurethane chain; and to construct a simplified molecular model based on the polyurethane chain and water molecules;

[0105] A molecular dynamics simulation module 002 is used to perform molecular dynamics simulation based on the simplified molecular model to obtain a tensile work value;

[0106] an average work calculation module 003, configured to calculate the average work based on the pulling work value using the Jarzynski formula;

[0107] The equilibrium free energy surface acquisition module 004 is used to perform an umbrella sampling simulation based on the movement trajectory of the water molecules in the molecular dynamics simulation, with the set position of the water molecules as the reaction coordinate, and solve the self-consistent equation through the MBAR strategy to obtain the equilibrium free energy surface;

[0108] A setting mapping model construction module 005 is used to compare the known experimental waterproof performance data with the average work and the equilibrium free energy surface to construct a setting mapping model;

[0109] The waterproof performance prediction module 006 is used to predict the input polyurethane film to be predicted by using the set mapping model, and output the waterproof performance prediction of the polyurethane film to be predicted.

[0110] In this embodiment, in the simplified molecular model construction module 001, during the molecular dynamics simulation based on the simplified molecular model:

[0111] External force is applied to the water molecules to make them penetrate the polyurethane film, and the work done by the tension is obtained by simulation trajectory calculation.

[0112] In this embodiment, in the average power calculation module 003, the calculation formula of the average power is:

[0113] e -βΔF = <e -βW >

[0114] Where β = 1 / k B T(k B is the Boltzmann constant) is the simulation temperature; <…> is the average treatment; W is the work done by the tension; ΔF is the average work; e=2.71828... is the base of the natural logarithm.

[0115] In this embodiment, in the equilibrium free energy surface acquisition module 004, during the umbrella sampling simulation:

[0116] The set position for sampling the water molecules is:

[0117]

[0118] Where R0 is the initial position of the water molecule; R1 is the current position of the water molecule in the molecular dynamics simulation; (d is the thickness of the polyurethane film in the simulation), that is, the number of windows in the umbrella sampling, which is selected so that the positions of water molecules in two adjacent structures differ by

[0119] In this embodiment, in the equilibrium free energy surface acquisition module 004, the process expression for solving the self-consistent equation by the MBAR strategy is:

[0120]

[0121] Where n j is the sampling number of trajectory j; V i (x jn ) is the bias potential calculated from the bias potential function of trajectory i for structure n in trajectory j; f i is the free energy; k is the trajectory.

[0122] It should be noted that the information interaction, execution process, etc. between the modules of the above-mentioned system are based on the same concept as the method embodiment in Example 1 of the present application, and the technical effects they bring are the same as those of the method embodiment of the present application. For specific contents, please refer to the description in the method embodiment shown above in the present application, and no further details will be given here.

[0123] Example 3

[0124] Embodiment 3 of the present invention provides a non-transitory computer-readable storage medium, in which a program code for a method for predicting the waterproof performance of a polyurethane film is stored. The program code includes instructions for executing a method for predicting the waterproof performance of a polyurethane film according to embodiment 1 or any possible implementation thereof.

[0125] Computer-readable storage media can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that includes one or more available media. The available media can be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., DVDs), or semiconductor media (e.g., solid-state drives (SSDs)).

[0126] Example 4

[0127] Embodiment 4 of the present invention provides an electronic device, including: a memory and a processor;

[0128] The processor and the memory communicate with each other via a bus; the memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute a method for predicting the waterproof performance of a polyurethane film according to Example 1 or any possible implementation thereof.

[0129] Specifically, the processor can be implemented by hardware or by software. When implemented by hardware, the processor can be a logic circuit, an integrated circuit, etc.; when implemented by software, the processor can be a general-purpose processor, which is implemented by reading software code stored in a memory. The memory can be integrated into the processor or located outside the processor and exist independently.

[0130] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present invention is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable systems. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website, computer, server or data center to another website, computer, server or data center via a wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode.

[0131] Obviously, those skilled in the art will appreciate that the various modules or steps of the present invention described above can be implemented using a general-purpose computing system. They can be centralized on a single computing system or distributed across a network of multiple computing systems. Alternatively, they can be implemented using program code executable by a computing system, and thus, they can be stored in a storage system and executed by the computing system. In some cases, the steps shown or described herein can be performed in a different order than that shown, or they can be fabricated into separate integrated circuit modules, or multiple modules or steps can be fabricated into a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0132] Although the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications and improvements may be made thereto. Therefore, such modifications and improvements, without departing from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A method for predicting the waterproof performance of a polyurethane film, characterized in that: include: According to the monomer structures of the polyol, isocyanate and chain extender of the target polyurethane, a polyurethane chain is formed; and based on the polyurethane chain and water molecules, a simplified molecular model is constructed; Based on the simplified molecular model, molecular dynamics simulation is performed to obtain the tensile work value; Based on the tensile work value, the average work is calculated using the Jarzynski formula; Based on the movement trajectory of the water molecules in the molecular dynamics simulation, an umbrella sampling simulation is performed with the set position of the water molecules as the reaction coordinate, and the self-consistent equation is solved by the MBAR strategy to obtain the equilibrium free energy surface; Comparing known experimental waterproof performance data with the average work and the equilibrium free energy surface respectively, and constructing a set mapping model; The input polyurethane film to be predicted is predicted through the set mapping model, and the waterproof performance prediction of the polyurethane film to be predicted is output.

2. The method for predicting the waterproof performance of a polyurethane film according to claim 1, characterized in that: During the molecular dynamics simulation based on the simplified molecular model: External force is applied to the water molecules to make them penetrate the polyurethane film, and the work done by the tension is obtained by simulation trajectory calculation.

3. The method for predicting the waterproof performance of a polyurethane film according to claim 2, characterized in that: The calculation formula of the average work is: and -βΔF = <e -βW > Where β = 1 / k B T(k B is the Boltzmann constant) is the simulation temperature; <…> is the average treatment; W is the work done by the tension; ΔF is the average work; e=2.71828... is the base of the natural logarithm.

4. The method for predicting the waterproof performance of a polyurethane film according to claim 3, characterized in that: During the umbrella sampling simulation: The set position for sampling the water molecules is: Where R0 is the initial position of the water molecule; R1 is the current position of the water molecule in the molecular dynamics simulation; d is the thickness of the polyurethane film in the simulation, that is, the number of windows in the umbrella sampling, which is set so that the positions of water molecules in two adjacent structures differ by 5. The method for predicting the waterproof performance of a polyurethane film according to claim 4, characterized in that: The process expression of solving the self-consistent equation by the MBAR strategy is: Where n j is the sampling number of trajectory j; V i (x jn ) is the bias potential calculated from the bias potential function of trajectory i for structure n in trajectory j; f i is the free energy; k is the trajectory.

6. A polyurethane film waterproof performance prediction device, using a polyurethane film waterproof performance prediction method according to any one of claims 1 to 5, characterized in that: include: A simplified molecular model building module is used to link the polyol, isocyanate and chain extender monomer structures of the target polyurethane to form a polyurethane chain; and to build a simplified molecular model based on the polyurethane chain and water molecules; A molecular dynamics simulation module, configured to perform molecular dynamics simulation based on the simplified molecular model to obtain a tensile work value; an average work calculation module, configured to calculate the average work based on the pulling work value using the Jarzynski formula; An equilibrium free energy surface acquisition module is used to perform an umbrella sampling simulation based on the movement trajectory of the water molecules in the molecular dynamics simulation, with the set position of the water molecules as the reaction coordinate, and solve the self-consistent equation through the MBAR strategy to obtain the equilibrium free energy surface; A setting mapping model construction module is used to compare known experimental waterproof performance data with the average work and the equilibrium free energy surface respectively to construct a setting mapping model; The waterproof performance prediction module is used to predict the input polyurethane film to be predicted through the set mapping model and output the waterproof performance prediction of the polyurethane film to be predicted.

7. The device for predicting the waterproof performance of a polyurethane film according to claim 6, characterized in that: In the simplified molecular model building module, during the molecular dynamics simulation based on the simplified molecular model: External force is applied to the water molecules to make them penetrate the polyurethane film, and the work done by the tension is obtained by simulation trajectory calculation.

8. The device for predicting the waterproof performance of a polyurethane film according to claim 7, characterized in that: In the average work calculation module, the calculation formula of the average work is: and -βΔF = <e -βW > Where β = 1 / k B T(k B is the Boltzmann constant) is the simulation temperature; <…> is the average treatment; W is the work done by the tension; ΔF is the average work; e=2.71828... is the base of the natural logarithm.

9. The device for predicting the waterproof performance of a polyurethane film according to claim 8, characterized in that: In the equilibrium free energy surface acquisition module, during the umbrella sampling simulation: The set position for sampling the water molecules is: Where R0 is the initial position of the water molecule; R1 is the current position of the water molecule in the molecular dynamics simulation; (d is the thickness of the polyurethane film in the simulation), that is, the number of windows in the umbrella sampling, which is selected so that the positions of water molecules in two adjacent structures differ by 10. The device for predicting the waterproof performance of a polyurethane film according to claim 9, characterized in that: In the equilibrium free energy surface acquisition module, the process expression for solving the self-consistent equation by the MBAR strategy is: Where n j is the sampling number of trajectory j; V i (x jn ) is the bias potential calculated from the bias potential function of trajectory i for structure n in trajectory j; f i is the free energy; k is the trajectory.

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