Monomer Screening Method for Prepartion of Aramid Fiber

Abstract

The present invention relates to a screening method for selecting monomers for the manufacture of aramid fibers by simulation using molecular dynamics. According to the present invention, the method comprises: a step of determining a reference value for the interaction energy per unit volume between existing polymer chains in the stretched state and molten state by simulating existing polymer chains constituting existing aramid fibers (Step (A)); a step of selecting preliminary replacement monomers from a chemical database according to filter criteria (monomers with a molecular structural complexity value of 800 or less, uncharged monomers, monomers in which the angle (θ) formed between the center of the monomer's molecular structure and the two terminal NH2s satisfies -1 ≤ cosθ < 0, and monomers in which the radius of rotation from the central axis of the monomer's molecular structure is 6 Å or less) (Step (B10)); and a step of constructing an initial structural model of the preliminary replacement polymer chains constituting the aramid fibers using the preliminary replacement monomers (Step (B20)). A screening method for selecting monomers is provided, comprising the step of selecting a final replacement monomer by simulation (step (B30)), wherein step (B10) includes a step of obtaining raw monomer data by keyword search from a chemical database (B10a), and a step of selecting preliminary replacement monomers satisfying the filter criteria from the raw monomer data (B10b). By the method of the present invention, monomers capable of producing aramid fibers with superior performance compared to existing aramid fibers are effectively selected from thousands to tens of thousands of databases with a high data throughput. By utilizing the monomers selected by the present invention, aramid fibers with superior physical properties can be easily manufactured.

Description

Technology Field

[0001] The present invention relates to a method for screening monomers for the manufacture of aramid fibers. Specifically, the present invention relates to a screening method for effectively selecting monomers suitable for the manufacture of high-performance aramid fibers from a chemical database. More specifically, the present invention relates to a screening method for effectively selecting monomers suitable for the manufacture of high-performance aramid fibers by simulation based on molecular dynamics. Background Technology

[0002] Aramid fibers are a type of synthetic fiber composed of polymer chains, which are linear macromolecules consisting of aromatic groups connected by amide or imide bonds, and possess excellent heat resistance and tensile strength. Aramid is an abbreviation for aromatic polyamide, and is defined as homoamides or copolyamides in which more than 85 mol% of the chain consists of aromatic monomer units.

[0003] Poly-p-phenylene terephthalamide (PPTA) and Technora® are widely known as existing aramid fibers. PPTA is one of the most well-known and widely used aramids (aromatic polyamides) worldwide, developed by DuPont of the United States. It is synthesized by the condensation reaction of terephthaloyl chloride (TPC) and p-phenylenediamine (1,4-phenylenediamine, PPD). Due to the characteristics of its chain bonding, it possesses properties such as a high tensile strength-to-weight ratio, high ballistic resistance, and heat resistance, and is used in various industrial fields such as aerospace and personal protective equipment. PPTA consists of the following repeating unit (1) formed by the reaction of TPC and PPD.

[0004] [Repetition Unit (1)]

[0005]

[0006] Technora® is a para-aramid fiber manufactured by the Japanese textile company Teijin, characterized by eight times the strength of steel, high modulus of elasticity, heat resistance, and chemical resistance. Technora® is produced by the condensation polymerization of three monomers: terephthaloyl chloride (TPC), p-phenylenediamine (PPD), and 3,4'-diaminodiphenylether (3,4'-ODA). Due to its excellent physical properties, it is used in various industrial fields such as ropes, optical fiber cables (OFC), high-pressure hoses, protective equipment, and heat-resistant and fire-resistant clothing. Technora consists of polymer chains containing two repeating units, the following repeating units (1) and (2). Repeating unit (1) is a repeating unit formed by the reaction of monomer TPC and PPD, and repeating unit (2) is a repeating unit formed by the reaction of monomer TPC and 3,4'-ODA.

[0007] [Repetition Unit (1)]

[0008]

[0009] [Repetition Unit (2)]

[0010]

[0011] As such, aramid fibers possessing excellent physical properties such as strength, heat resistance, tensile strength, and elasticity are used in various industrial fields, and research is being conducted on the development of high-performance aramid fibers with even better properties.

[0012] Meanwhile, as data processing and manipulation methods have become digitized, databases for numerous substances have been established. Information on the structure and physical properties of monomers is also databased, and desired information can be easily obtained from chemical databases covering molecules, biology, and drugs, such as PubChem and ChemBL. However, there are limitations to conducting experiments to verify the utility of every single monomer dataset. Therefore, reducing the number of monomers to be tested and proceeding with experiments on those identified as promising is highly beneficial in terms of both economy and time. Accordingly, high-throughput screening methods for vast amounts of data are required.

[0013] Japanese Patent Publication No. 2013-002013 discloses a method for creating a fiber model, but it merely discloses the prediction of interfacial peeling characteristics between a fiber material and an adhesive by elucidating the adhesion mechanism between the fiber material and the adhesive through the simulation of a fiber material model, and does not disclose the selection of monomers for manufacturing aramid fibers with excellent physical properties as in the present invention. The problem to be solved

[0014] The present invention provides a screening method for selecting monomers suitable for manufacturing aramid fibers by simulation based on molecular dynamics.

[0015] In addition, the screening method for selecting monomers for the production of aramid fibers according to the present invention presents a new criterion for selecting monomers suitable for the production of high-performance aramid fibers.

[0016] In other words, the present invention provides a monomer screening method that enables high-performance screening of monomers promising for the manufacture of aramid fibers that are believed to possess suitable physical properties from a database of thousands to tens of thousands of items, and through such screening, selects a final alternative monomer suitable for the manufacture of aramid fibers with superior performance to existing aramid fibers. means of solving the problem

[0017] According to the first aspect, as a monomer screening method for manufacturing aramid fibers,

[0018] Step (A) for determining reference values ​​for interaction energy per unit volume in the stretched and molten states between existing polymer chains by simulation based on the molecular dynamics of existing polymer chains constituting existing aramid fibers;

[0019] Preliminary replacement monomer screening step based on filter criteria from a chemical database (step (B10));

[0020] Step of constructing an initial structural model of a preliminary replacement polymer chain constituting an aramid fiber using a preliminary replacement monomer (step (B20)); and

[0021] It includes a step of selecting a final replacement monomer by simulation based on the molecular dynamics of a preliminary replacement polymer chain structure model constituting the aramid fiber (step (B30)), and

[0022] The above step (B10) is,

[0023] Step of obtaining raw monomer data by keyword search from a chemical database (B10a), and

[0024] A method is provided comprising a preliminary replacement monomer selection step (B10b) that satisfies the following filter criteria (1) to (4) from raw monomer data.

[0025] Filter criteria (1): Monomers with a molecular structural complexity value of 800 or less,

[0026] Filter criterion (2): uncharged monomer,

[0027] Filter criteria (3): A monomer in which the angle (θ) formed by the center of the molecular structure of the monomer and the NH2 at both ends satisfies -1 ≤ cosθ < 0, and

[0028] Filter criterion (4): A monomer having a radius of rotation of 6 Å or less from the central axis of the molecular structure of the monomer.

[0029] According to the second aspect, a method is provided in which, in step (A), the existing aramid fiber is poly-p-phenylene terephthalamide or Technora®.

[0030] According to the third view, the above step (B20) is

[0031] Step (B20a) of obtaining an information file on atoms constituting a preliminary replacement monomer from SMILE format data for a preliminary replacement monomer selected in step (B10b),

[0032] Step (B20b) of converting the information file on atoms constituting the preliminary replacement monomer obtained in step (B20a) into an input format file for simulation progress, and

[0033] A method is provided comprising the step (B20c) of constructing an initial structural model of a preliminary replacement polymer chain constituting an aramid fiber from a preliminary replacement monomer of the input format obtained in step (B20b).

[0034] According to the fourth view, the above step (B30) is:

[0035] Step (B30a) of fabricating a simulation box in which an initial structural model of the preliminary replacement polymer chain generated in the above step (B20c) is placed in the simulation box, thereby constructing a preliminary replacement polymer chain structural model,

[0036] Stabilization step of the preliminary alternative polymer chain structure model (B30b),

[0037] Simulation step of a preliminary alternative polymer chain structure model using a straight frame ensemble (B30c),

[0038] Simulation step of a preliminary alternative polymer chain structure model using an isothermal-isobaric ensemble (B30d),

[0039] After step (B30d), a simulation step (B30e) of the preliminary replacement polymer chain structure model in a state where the preliminary replacement polymer chain structure is stretched along the x-axis by applying tensile force;

[0040] After step (B30e), release the tensile force and simulate the preliminary alternative polymer chain structure model using an isothermal-isobaric ensemble (B30e');

[0041] Step (B30gs) in which the interaction energy value between the convergent preliminary replacement polymer chains in the simulation of step (B30e') is divided by the volume of the simulation box to obtain the interaction energy value per volume between the preliminary replacement polymer chains, and this is used as the interaction energy value per volume of the stretched state between the preliminary replacement polymer chains;

[0042] After step (B30d), a simulation step (B30f) of a preliminary alternative polymer chain structure model in a molten state by annealing;

[0043] Simulation step (B30f') of a preliminary alternative polymer chain structure model using an isothermal and isobaric ensemble after step (B30f);

[0044] The method includes a step (B30gm) in which the interaction energy value between the convergent preliminary replacement polymer chains in the simulation of step (B30f') is divided by the volume of the simulation box to obtain the interaction energy value per volume, and this is used as the interaction energy value per volume of the molten state between the preliminary replacement polymer chains.

[0045] The interaction energy per volume of the stretched state between the preliminary replacement polymer chains in step (B30gs) is smaller than the reference value of the interaction energy per volume of the stretched state between the existing polymer chains in step (A), and

[0046] A method is provided for selecting a preliminary replacement monomer included in a preliminary replacement polymer chain structure model as the final replacement monomer, wherein the interaction energy per volume of the molten state between the preliminary replacement polymer chains of step (B30 gm) is greater than the reference value of the interaction energy per volume of the molten state between the existing polymer chains of step (A).

[0047] According to the fifth aspect, a method is provided in which the final substitute monomer is a substitute monomer for the 3,4'-diaminodiphenyl ether monomer of Technora.

[0048] According to the sixth view, the selected final substitute monomer is 3-[(4-aminophenyl)methyl]aniline, 4-[[4-[(4-aminophenyl)methyl]phenyl]methyl]aniline, 4-[(Z)-N-[(Z)-1-(4-aminophenyl)ethylideneamino]-C-methylcarbomimidoyyl]aniline, 3-[4-(3-aminophenoxy)phenoxy]aniline, 3-[5-(4-aminophenyl)-1H-1,2,4-triazole-3-yl]aniline, 4-[[4-[(4-aminophenyl)methyl]phenyl]methyl]aniline, 4-[4-(4-aminophenoxy)-3-methylphenoxy]aniline, 3-[6-(3-aminophenoxy)pyridine-2-yl]oxyaniline, 4-[6-[5-(4-aminophenoxy)pyridine-2-yl]pyridine-3-yl]oxyaniline, 3-[4-[4-(3-aminophenoxy)phenyl]sulfanylphenoxy]aniline, 3-[2-(4-aminophenoxy)ethoxy]aniline, 3-[4-[(4-aminophenoxy)methyl]-2-methyl-1,3-dioxolane-2-yl]aniline, 4-[2-[4-(4-aminophenoxy)phenyl]ethyl]aniline, 3-[(3-aminophenoxy)methoxy]aniline, 3-(3-aminophenoxy)aniline, 3-[4-(4-aminophenoxy)phenoxy]aniline, 4-[4-[[4-(4-aminophenoxy)phenyl]diazenyl]phenoxy]aniline, Pyridine-2,6-diamine, pyrimidine-2,5-diamine, [3-(aminomethyl)phenyl]methaneamine, (1S,3R,4R)-4-fluorocyclopentan-1,3-diamine, 1,2-diamino-1,2,4-triazolidin-3-ol, 4-fluoropyridine-3,5-diamine, 2-N-methyl-1,3,5-triazine-2,4,6-triamine, 2,6-diaminopyridine-3-ol, 3-fluoropyridine-2,6-diamine, (2S,3R,6S)-3-amino-6-(aminomethyl)oxan-2-ol, 2H-triazine-1,5-diamine, 1,8-naphthylidine-2,7-diamine, 6-hydroxypyrazole[1,5-c]triazol-3,5-diamine, N,6-diamino-N-methylpyridine-2-carboxyimideamide, (1R)-1,5-diamino-2,3-dihydro-1H-indene-4-ol, 1,5-diamino-2,3-dihydro-1H-indene-4-ol, (1S)-1,5-diamino-2,3-dihydro-1H-indene-4-ol, (3R)-3,6-diamino-2,3-Dihydro-1-benzofuran-5-ol, 2,5-diamino-3-hydroxybenzoic acid, 4H-chromene-2,7-diamine, 4-[(4-aminophenyl)methyl]-2-methylaniline, 3-[(3-aminophenyl)diazenyl]aniline, 1,5-diaminonaphthalene-2-carboxylic acid, 3-amino-N-(3-aminophenyl)benzamide, 3-[4-[3-[4-(3-aminopropyl)phenoxy]propoxy]phenyl]propan-1-amine, 3-[4-(3-aminopropoxy)cyclohexyl]oxypropan-1-amine, 3-[4-[2-[4-(3-aminopropyl)phenoxy]ethoxy]phenyl]propan-1-amine, A method is provided comprising a monomer selected from 3-[6-(3-aminopropyl)pyridine-3-yl]propan-1-amine, 2-amino-1-[4-[4-(2-aminoacetyl)phenoxy]phenyl]ethanolone, 2-[3-[3-(2-aminoethoxy)phenyl]phenoxy]ethanolamine, and 2-[4-[2-[2-[2-[2-[4-(2-aminoethoxy)phenyl]ethoxy]ethoxy]ethoxy]ethyl]phenoxy]ethanolamine. Effects of the invention

[0049] By the monomer screening method for manufacturing aramid fibers according to the present invention, monomers capable of manufacturing aramid fibers with superior performance compared to existing aramid fibers are effectively selected from a database of thousands to tens of thousands of entries with high data throughput and / or high reliability. Furthermore, the screening method of the present invention enables the production of aramid fibers with superior physical properties capable of replacing existing aramid fibers by manufacturing aramid fibers using the selected monomers. Brief explanation of the drawing

[0050] Figure 1a is a flowchart showing the step (A10) of constructing an initial structural model of existing polymer chains constituting existing aramid fibers to proceed with a simulation based on molecular dynamics. Figure 1b is a flowchart showing the step (A20) of determining the reference value of the interaction energy per unit volume between existing polymer chains constituting the existing arimide fiber through a simulation based on molecular dynamics. FIG. 2a is a flowchart showing the preliminary replacement monomer selection step (B10) according to filter criteria from a chemical database. FIG. 2b is a flowchart showing the initial structural model construction step (B20) of a preliminary replacement polymer chain constituting an aramid fiber using a preliminary replacement monomer. FIG. 2c is a flowchart showing the final replacement monomer selection step (B30) by simulation based on the molecular dynamics of a preliminary replacement polymer chain structure model constituting the aramid fiber. FIG. 3a is a diagram showing the angle (θ) formed by the center of the molecular structure of the monomer and the NH2 at both ends, and FIG. 3b is a diagram showing the radius of rotation (r) from the central axis of the molecular structure of the monomer. Figure 4a is an arrangement of monomers constituting Technora obtained in Example 1, and Figure 4b is an initial structural arrangement of polymer chains constituting Technora obtained in Example 1. Figure 5a shows a simulation box for the polymer chains constituting Technora of Example 1, and Figure 5b shows the simulation box of Figure 5a at a different point in time. Figure 6a is the arrangement of monomers constituting PPTA obtained in Example 1, and Figure 6b is the initial structural arrangement of polymer chains constituting PPTA obtained in Example 1. Figure 7 is a graph showing the interaction energy per molecule between polymer chains in the stretched state and the molten state obtained from a simulation based on the molecular dynamics of the polymer chain structure model constituting the arimide fiber of Example 1. Specific details for implementing the invention

[0051] The present invention relates to a screening method for selecting monomers suitable for manufacturing high-performance aramid fibers from a chemical database. The screening method of the present invention comprises determining a reference value for the interaction energy per unit volume between existing polymer chains in the stretched and molten states by a simulation based on the molecular dynamics of existing polymer chains constituting existing aramid fibers (hereinafter referred to simply as "simulation") (a reference value determination step (step (A)), and selecting a final replacement monomer (a final replacement monomer selection step (step (B))) by comparing the interaction energy per unit volume between preliminary replacement polymer chains in the stretched and molten states, obtained by a simulation of preliminary replacement polymer chains constituting aramid fibers constructed from monomers selected according to specific filter criteria from a chemical database, with the reference value. Each step of the screening method of the present invention will be described in detail below.

[0052] Step A: Determination of reference values ​​for interaction energy per unit volume in the stretched and molten states between existing polymer chains constituting the existing aramid fibers

[0053] Step A (hereinafter referred to as the 'reference value determination step (A)') includes a step (A10) of constructing an initial structural model of existing polymer chains constituting the existing aramid fiber to be simulated, and a step (A20) of determining a reference value of the interaction energy per unit volume of the stretched state and molten state between existing polymer chains constituting the existing aramid fiber through simulation. Flowcharts of Step (A10) and Step (A20) are shown in FIGS. 1a and FIGS. 1b, respectively. The polymer chains constituting the aramid fiber are hereinafter referred to as 'aramid polymer chains' or 'polymer chains'.

[0054] In the reference value determination step (A), the reference values ​​for the interaction energy per unit volume of the polymer chains in the stretched state and molten state, which serve as the criteria for monomer selection in the method of the present invention, are determined by simulating the existing polymer chain structure of the existing aramid fiber.

[0055] The present invention is to select a monomer (hereinafter also referred to as the 'final replacement monomer') for producing an aramid fiber with superior physical properties compared to the Technora® aramid fiber, based on the existing Technora® aramid fiber. Meanwhile, Technora® is an aramid fiber produced by the condensation polymerization of TPC, PPD, and 3,4'-ODA monomers, and thus, Technora is composed of a polymer chain containing repeating units of the above chemical formulas (1) and (2).

[0056] Accordingly, by simulating polymer chains containing repeating units (1) and (2) formed by the condensation polymerization of TPC, PPD, and 3,4'-ODA, the interaction energy values ​​per molecule in the elongated and molten states of the polymer chains constituting the technora fiber are obtained and set as reference values. This process is described in detail below.

[0057] Step (A10): Step for creating an initial structural model of the existing polymer chains constituting the existing aramid fiber to be simulated.

[0058] Step (A10) includes the steps of obtaining monomer data constituting the existing aramid fiber from a chemical database (A10a), obtaining an information file on atoms constituting the monomer from the monomer data obtained in step (A10a) (A10b), converting the information file on atoms constituting the monomer obtained in step (A10b) into an input format for simulation progress (A10c), and constructing an initial structural model of the existing polymer chain constituting the existing aramid fiber from the monomer in the input format obtained in step (A10c) (A10d).

[0059] In step (A10a), data for TPC, PPD, and 3,4'-ODA monomers is obtained from a chemical database. At this time, the data for the monomers from the chemical database is provided as a file in SMILE format. The chemical database may be any known chemical database, and is not limited thereto, examples include PubChem, ChemBL, etc.

[0060] The Simplified Molecular-Input Line-Entry System (SMILES) is a specification in the form of line notation used to describe the structure of chemical species by utilizing strings of English alphabet characters. It is a notation that allows various machine learning and deep learning algorithms to be applied to molecular structures by representing them in string form. In SMILES notation, each atom is indicated by its corresponding element symbol, while hydrogen is omitted. Bonds between atoms are indicated by eight symbols, such as ".", "-", "=", "#", and "@". Rings are represented by breaking the bond at one point and marking the two atoms in that section with numbers. Molecular branches are represented by parentheses (), and the first atom inside the parentheses and the first atom after the parentheses end are connected to the same atom. SMILES notation is generally known in this technical field, and the molecular structure of a selected monomer is presented according to the SMILES notation commonly used in the industry; a detailed description thereof is omitted.

[0061] Then, in step (A10b), an information file for atoms constituting the monomer is obtained from the TPC, PPD, and 3,4'-ODA monomer data in SMILE format (smi format) selected in step (A10a). Specifically, the information file for atoms constituting the monomer includes the type, position value (coordinate value), and partial charge value of each atom constituting the monomer.

[0062] Specifically, in step (A10b), the partial charge value of the atom is calculated using the Electronegativity Equalization Method (EEM), which is one of the methods for calculating charge using open computer software, such as the openbabel program tool. When monomer data information in SMILES format is input into the open-source openbabel, information about the monomer, including the partial charge value of the atom constituting the monomer, the type of atom, and the position value (coordinate value), is obtained in a mol2 format file. Accordingly, an information file in mol2 format is obtained for the information (type of atom, position value (coordinate value), partial charge value) for each atom constituting the TPC, PPD, and 3,4'-ODA monomers.

[0063] After that, in step (A10c), the mol2 format information file for the atoms constituting the monomer obtained in step (A10b) is converted into an input format for proceeding with the simulation. Specifically, using the Antechamber program, the list of atoms in the mol2 format information file obtained in step (A10b) is rearranged (reassigned). Based on the reassigned mol2 format file, it is converted into an lt file, which is an input format recognizable by Moltemplate. The lt file format contains coordinates and charge values ​​for the monomer and is a file format that can be accepted by Moltemplate, a simulation box creation program for molecular dynamics simulation.

[0064] Suitable manipulation of monomer information (specifically, information regarding each atom constituting the monomer) and methods thereof, including file format conversion and transformation, for the production of a simulation box are matters generally known to those skilled in the art and are not described in detail here.

[0065] Then, in step (A10d), an initial structural model for simulating a polymer chain constituting a techno fiber containing the repeating units (1) and (2) is constructed by specifying the bonds between monomers in the information on atoms constituting the TPC, PPD, and 3,4'-ODA monomers in the lt file format in Moltemplate.

[0066] Step (A20): Determination of reference values ​​for interaction energy per unit volume in the stretched and molten states between existing polymer chains constituting existing arimide fibers through simulation.

[0067] Step (A20) includes a simulation box fabrication step (A20a), a stabilization step of an existing polymer chain structure model (A20b), a simulation step of an existing polymer chain structure model using a straight frame ensemble (A20c), a simulation step of an existing polymer chain structure model using an isothermal-isobaric ensemble (A20d), a simulation step of an existing polymer chain structure model in an elongated state with tensile force applied (A20e), a simulation step of an existing polymer chain structure model after tensile force release (A20e'), a step of obtaining a reference value for per-molecular interaction energy between existing polymer chains in an elongated state (A20gs), a simulation step of an existing polymer chain structure model in a molten state by annealing (A20f), a simulation step of an existing polymer chain structure model after annealing (A20f'), and a step of obtaining a reference value for per-molecular interaction energy between existing polymer chains in a molten state (A20gm).

[0068] The simulation box is fabricated using Moltemplate, and the simulation, stabilization, and calculation of interaction energies in the simulation are performed using the Large-scale Atomic / Molecular Massively Parallel Simulator (LAMMPS), an open-source molecular dynamics code package. Specifically, as the simulation is performed, the interaction energies between polymer chains are calculated by Equation 1, which is stored in LAMMPS.

[0069] [Equation 1]

[0070]

[0071] Equation 1 above represents the basic simulation steps for molecular dynamics. In molecular dynamics simulations, the energy values ​​at each stage and in the system can be obtained using Equation 1, and relative comparisons are performed using these values. Specifically, given the initial position (x(t)) and velocity (v(t)) values, the position (x(t+dt)) and velocity (v(t+dt)) of the next stage are calculated using Newton's equations. The system's energy (E) is calculated using the calculated position and velocity values. The force (F) is obtained by differentiating the obtained energy (E) value. Dividing the obtained force by the mass (m) yields acceleration, and a new velocity is calculated using this acceleration. Information regarding the next molecular position can also be calculated using the calculated velocity. The simulation proceeds by repeating this method to obtain the final value (energy value), which is then utilized.

[0072] In the simulation box fabrication step (A20a), a simulation box is fabricated to perform a simulation using the existing polymer chain initial structure model obtained in step (A10d). An infinitely connected chain exists along the x-axis of the simulation box, and a periodic boundary is established for the simulation box. A single chain composed of eight repeating units (i.e., four repeating units (1) and (2) each, and the arrangement of repeating units (1) and (2) is random) is placed along the x-axis inside the established boundary. Meanwhile, five of the single chains composed of eight repeating units are placed along the y-axis and z-axis of the simulation box. The size of the simulation box depends on the size of the repeating units constituting the polymer chain to be simulated and / or the size of the monomers forming the repeating units. Specifically, the size of the x-axis forming the periodic boundary depends on the size of the repeating units, and the sizes of the y-axis and z-axis can be fabricated within the range of 180 Å to 220 Å each so that the polymer chains can be positioned at a sufficient distance without overlapping. When placing polymer chains in a simulation box, if the distance between polymer chains is too close, the polymer chains will become entangled with each other, so it is desirable to have a sufficient distance of 180 Å or more. If the distance between polymer chains is too far, a long time is required for the subsequent stabilization step, so it is desirable to have a distance of 220 Å or less.

[0073] In the simulation box manufactured in step (A20a), the existing polymer chain structure is artificially arranged, so the polymer chain structure is very unstable. Therefore, in the stabilization step (A20b), the existing polymer chain structure within the simulation box manufactured in step (A20a) is stabilized. In the stabilization step (A20b), values ​​of tolerable energy and force (set values) serving as stabilization criteria are set, and a simulation is performed. If the energy and force of the polymer chain structure model placed within the simulation box become less than or equal to the set values, it is determined that the polymer chain structure is stabilized, and step (A20c) is proceeded.

[0074] In step (A20c), a simulation is performed using a frame ensemble in which the number of particles, volume, and temperature are kept constant. The polymer chain structure is further stabilized by the simulation in step (A20c). The simulation in step (A20c) continues until the interaction energy value between the existing polymer chains converges to a constant value. At this point, the energy value at which it converges depends on the monomer and / or repeating unit and / or polymer chain, and this is also true for the simulations in subsequent steps.

[0075] After step (A20c), in step (A20d), a simulation of the existing polymer chain structure model is performed using an isothermal-isobaric ensemble in which the number of particles, pressure, and temperature are constant. The polymer chain structure is further stabilized by the simulation in step (A20d). The simulation in step (A20d) is also performed until the interaction energy value between polymer chains converges to a constant value.

[0076] After the simulation of the above step (A20d), a simulation using an isothermal-isobaric ensemble is performed for two states of the polymer chain structure: a stretched state (state in which it is manufactured into a fiber) and a melted state (fiber manufacturing process). This is to select a new monomer by comparing the interaction energy values ​​per unit volume of the existing polymer chains constituting the existing aramid fiber in the stretched state and the melted state during the process of selecting a new monomer.

[0077] The simulation of the stretched state in step (A20e) is performed after the completion of the simulation in step (A20d) by applying a tensile force to the simulation box so that the polymer chain structure in the simulation box becomes stretched. The simulation is performed in an isobaric-isothermal ensemble by applying a tensile force so that the polymer chain structure in the simulation box has an elongation rate of 5% to 20% in the x-axis direction. If the elongation rate is less than 5%, the elongation of the polymer chain structure is insufficient, and if it exceeds 20%, the length of the polymer chain becomes abnormally long and a suitable simulation cannot proceed. The simulation of the stretched state in step (A20e) is intended to simulate the stretched state of the polymer chain constituting the fiber, and while simulating, a tensile force is applied so that the polymer chain structure in the simulation box is stretched with an elongation rate of 5% to 20% in the x-axis direction, and the simulation period is not particularly limited. Meanwhile, the simulation of the stretched state in step (A20e) can also be performed by stretching the polymer chain structure in the x-axis direction with an elongation rate of 5% to 20%, and determining the end point of the simulation of the stretched state through energy convergence.

[0078] After the above step (A20e), subsequently, the existing polymer chain structure model is simulated using an isothermal-isobaric ensemble until it converges to a constant interaction energy value with the tensile force released (step (A20e'). The interaction energy value that converges in the simulation of step (A20e') is divided by the volume of the simulation box to set the reference value for the interaction energy per unit volume of the existing polymer chain structure in the stretched state (step (A20gs)).

[0079] Meanwhile, the simulation of the molten state in step (A20f) is performed after the simulation of step (A20d) is completed, by simulating the existing polymer chain structure model in a constant atomic number and isobaric ensemble while annealing the simulation box. The annealing heat treatment is performed by raising the temperature of the simulation box to a high temperature of approximately 2800K to 3000K and then lowering it to room temperature (e.g., 288K to 300K). The simulation of the molten state in step (A20f) is raised to a high temperature of approximately 2800K to 3000K in consideration of the fact that if annealing is performed at too high a temperature, the time required to reach the high temperature increases, whereas if it is performed at a low temperature, there is a possibility that annealing will not be properly carried out.

[0080] The simulation of the molten state in step (A20f) is intended to simulate the molten state of the polymer chains constituting the fibers. During the simulation, the temperature of the simulation box (i.e., the polymer chain structure model placed in the simulation box) is raised to a high temperature of approximately 2800K to 3000K, and then an annealing heat treatment is performed to bring it to room temperature (e.g., 288K to 300K). The rate of temperature rise and fall during the annealing heat treatment, the holding time at the high temperature, the simulation period, etc., are not particularly limited.

[0081] After the above step (A20f), the existing polymer chain structure is simulated until it converges to a constant interaction energy value in the isothermal isobaric ensemble in step (A20f'). The energy value that converges in step (A20f') is divided by the volume of the simulation box and set as the reference value for the interaction energy per unit volume of the molten state between the existing polymer chain structures (step (A20gm)).

[0082] Step (B): Final replacement monomer selection step

[0083] The final replacement monomer selection step (step (B)) is performed by including: a preliminary replacement monomer selection step (B10) based on filter criteria from a chemical database; a preliminary replacement polymer chain structure model construction step (B20) using the selected preliminary replacement monomers; and a final replacement monomer selection step (B30) based on simulation of the molecular dynamics of the preliminary replacement polymer chain structure model constituting the aramid fiber. Flowcharts of steps (B10) to (B30) are respectively shown in FIGS. 2a to 2c.

[0084] Step (B10): Preliminary replacement monomer screening step based on filter criteria from chemical database

[0085] In step (B10) (monomer selection step), preliminary substitute monomers suitable for manufacturing aramid fibers are selected from a chemical database according to filter criteria. Step (B10) includes a step of obtaining raw monomer data by keyword search from a chemical database (B10a), and a step of selecting monomers that satisfy filter criteria from the raw monomer data (B10b).

[0086] In step (B10a), raw data on the monomer is obtained by utilizing a comprehensive keyword search for the monomer to be selected in a chemical database.

[0087] The present invention is to select a monomer for producing aramid fibers with superior physical properties compared to Technora aramid fibers, based on existing Technora aramid fibers.

[0088] As described above, Technora® aramid fibers consist of polymer chains that randomly include repeating units (1) formed by the reaction of monomer TPC and PPD and repeating units (2) formed by the reaction of monomer TPC and 3,4'-ODA. Specifically, in the present invention, a substitute monomer for 3,4'-ODA is selected among the three monomers constituting Technora.

[0089] Accordingly, for example, in step (B10a), a monomer suitable for use as a substitute monomer for 3,4'-ODA is obtained as raw monomer data through keyword search. The chemical database may be any known chemical database, and is not limited thereto, examples include PubChem, ChemBL, etc.

[0090] For example, raw monomer data is obtained from the PubChem DB using keywords such as 'diamino', 'diamyline', 'bisaniline', 'aminophenoxy aniline', 'bis aminophenoxy', 'phenoxy propylamine', 'phenoxy ethylamine', 'naphthalenyloxy amine', 'bis ethanamine', 'bis propanamine', 'bis ethylamine', and 'bis propylamine'. Specifically, data is searched for each of the above keywords, and the total sum of the searched data is considered as raw data.

[0091] Raw monomer data in chemical databases (e.g., PubChem, ChemBL, etc.) is provided in SMILES format. Furthermore, the SMILES format is provided in these databases along with the monomer's physical property information. Therefore, the SMILES format provided in existing databases can be used as is without modification or additional processing. Additionally, for monomers for which the SMILES format is unknown, the structure can be obtained by utilizing PubChem's draw structure function.

[0092] After that, in step (B10b), the raw monomer data obtained in step (B10a) is filtered using the following filter criteria (1) to (4) to select a preliminary replacement monomer.

[0093] Aramid fibers are fibers composed of polymer chains, which are linear macromolecules consisting of aromatic groups connected by amide or imide bonds. Since they must be synthesizable for actual use, they are filtered to satisfy the following four filter criteria.

[0094] Filter criterion (1): Monomers with a structural complexity value of 800 or less

[0095] In the case of complex molecules, not only is synthesis difficult, but the monomers are generally expensive. Considering this, structural complexity of the monomer molecule is used as a filtering criterion to select monomers that are easy to obtain and easy to synthesize. Specifically, monomers with a structural complexity value of 800 or less are filtered and selected.

[0096] Molecules with a structural complexity value exceeding 800 are generally very complex molecules, which not only make synthesis difficult but also result in expensive reagents. Additionally, since monomers with a complexity value exceeding 800 may contain functional groups capable of causing side reactions, monomers with a structural complexity value of 800 or less are preferred.

[0097] The lower the complexity value, the higher the likelihood that the molecule has a simple structure and possesses only the desired functional groups, thus reducing the probability of side reactions. Therefore, the lower limit of complexity is not specifically restricted, and the minimum value of the structural complexity of a molecule is 0. The aforementioned complexity is an intrinsic property of a molecule, and structural complexity values ​​for monomer molecules are provided in databases such as PubChem.

[0098] Filter criterion (2): Uncharged monomer

[0099] If monomers carry an electrical charge, they may ionize during the reaction, leading to various side reactions. Due to these effects, the polymerization of the polymer chains constituting the aramid fibers may not proceed properly. Therefore, neutral monomers that do not carry an electrical charge are selected.

[0100] Therefore, by using non-charged monomers as the filter standard, monomers containing + or - are filtered out from the raw monomer data obtained in SMILE format in step (B10b).

[0101] Filter criterion (3): A monomer in which the cosθ of the angle (θ) between the center and the NH2 at both ends of the molecular structure is less than 0

[0102] This is explained with reference to Fig. 3a, which shows the angle (θ) formed by the center and the two terminal NH2 groups of the monomer's molecular structure.

[0103] It is desirable for aramid polymer chains to form a linear structure and be densely packed among the polymer chains in terms of physical properties such as strength and heat resistance of the aramid fiber. Meanwhile, linear aramid polymer chains can be formed as the angle (θ) between the center of the monomer's molecular structure and the two terminal NH2 groups approaches 180˚. Therefore, to form linear aramid polymer chains, monomers with an angle (θ) of 90˚ or greater are selected. That is, the cosθ value is calculated using the angle (θ) between the center of the monomer and the two terminals, and monomers having a cosθ value less than 0 are selected. In other words, monomers where -1 ≤ cosθ < 0 are selected.

[0104] Filter criterion (4): Monomers with a radius of rotation of 6 Å or less from the central axis of the molecular structure of the monomer

[0105] This is explained with reference to Fig. 3b, which shows the radius of rotation (r) from the central axis of the monomer.

[0106] Even if the angle (θ) between the center and the two terminal NH2s of the monomer is close to 180°, if the radius of rotation from the central axis of the monomer's molecular structure is large, inter-chain packing is not well formed, resulting in empty spaces between chains, which can lead to poor physical properties of the aramid fiber (e.g., strength, heat resistance, etc.).

[0107] Accordingly, monomers are selected such that the radius of rotation (r) of the molecule is 6 Å or less from the central axis of the molecular structure of the monomer. If the radius of rotation (r) exceeds 6 Å, it is undesirable because packing between polymer chains is not easy, and thus high-strength fibers are not produced. Since packing between polymer chains is more desirable as the radius of rotation (r) is shorter, the lower limit of the radius of rotation (r) is not limited.

[0108] By applying filter criteria (1) to (4) to the chemical database, data regarding monomers satisfying filter criteria (1) to (4) among the raw monomer data is provided in the chemical database. The filter criteria are written in C++ code and applied to the chemical database.

[0109] By the monomer selection step of step (B10), the monomer to be simulated can be selected in a short time by filtering according to filter criteria that provide criteria for the desired physical properties from thousands of chemical databases, thereby saving economic and time costs. The monomer selected in step (B10) is also referred to herein as a 'preliminary replacement monomer'. Additionally, the polymer chain composed including the 'preliminary replacement monomer' is also referred to herein as a 'preliminary replacement polymer chain'. To distinguish it from this, the polymer chain constituting the existing aramid fiber is referred to as the 'existing polymer chain'. The monomer finally selected as a replacement for the monomer constituting the polymer chain of the existing aramid fiber is referred to as the 'final replacement monomer'.

[0110] Step (B20): Step of constructing an initial structural model of the pre-replacement polymer chain constituting the aramid fiber using the pre-replacement monomer.

[0111] In step (B20), an initial structural model of a preliminary replacement polymer chain to be simulated is generated using data on the preliminary replacement monomer selected in step (B10b). Step (B20) includes a step (B20a) of obtaining an information file on atoms constituting the preliminary replacement monomer from the data on the preliminary replacement monomer in SMILE format selected in step (B10b); a step (B20b) of converting the information file on atoms constituting the preliminary replacement monomer obtained in step (B20a) into an input format file for simulation execution; and a step (B20c) of constructing an initial structural model of a preliminary replacement polymer chain constituting the aramid fiber from the input format preliminary replacement monomer obtained in step (B20b).

[0112] Steps (B20a) through (B20c) are performed for each preliminary replacement monomer selected in step (B10b). Furthermore, steps (B20a) and (B20b) are identical to steps (A10b) and (A10c), except that data for the preliminary replacement monomer selected in step (B10b) is used. Additionally, in step (B20c), the content described in step (A10d) is identical to step (A10d), except that a preliminary replacement monomer of the lt input format obtained in step (B20b) is bonded to replace the existing monomer portion of the repeating unit of the existing polymer chain constituting the existing aramid fiber, thereby generating an initial structural model of the preliminary replacement polymer chain. Therefore, the content identical to steps (A10b) through (A10d) is not described repeatedly.

[0113] Specifically, an initial structural model of a preliminary replacement polymer chain is generated in which the 3,4'-ODA portion, which is the existing monomer among the repeating units of the existing aramid polymer chain, is replaced with each preliminary replacement monomer selected in step (B10b). The initial structural model of the preliminary replacement polymer chain constructed in step (B20c) includes, for example, the following repeating units (1) and (3).

[0114] As described above, the repeating unit (1) is a repeating unit formed by the reaction of monomer TPC and PPD, and the repeating unit (3) is a repeating unit composed of monomer TPC and each preliminary replacement monomer selected in step (B10b) (the -NH-A-NH- portion of the repeating unit (3) below). The -NH-A-NH- portion of the repeating unit (3) is a portion derived from the structure of each preliminary replacement monomer selected in step (B10b), and such a repeating unit (3) is prepared as a preliminary replacement repeating unit for the repeating unit (2).

[0115] Repeating unit (1) is derived from the TPC and PPD monomer portions that constitute the existing Technora fiber, and the B portion of repeating unit (3) is derived from the TPC monomer portion.

[0116] Accordingly, a preliminary replacement polymer chain containing repeating units (1) and (3) is obtained by applying data for TPC, PPD, and the preliminary replacement monomers to steps (B20a) through (B20c). Monomer data for TPC and PPD monomers can be obtained from an existing chemical database as described in step (A10).

[0117] [Repetition Unit (1)]

[0118]

[0119] [Repetition Unit (3)]

[0120]

[0121] (In the above repeating unit (3), the B portion is derived from the TPC monomer, and the -NH-A-NH- portion is derived from each preliminary replacement monomer selected in step (B10b).)

[0122] Step (B30): Final replacement monomer selection step based on simulation of molecular dynamics of a preliminary replacement polymer chain structure model constituting the aramid fiber.

[0123] Step (B30) includes a simulation box fabrication step (B30a), a stabilization step of a preliminary replacement polymer chain structure model (B30b), a simulation step of a preliminary replacement polymer chain structure model using a straight frame ensemble (B30c), a simulation step of a preliminary replacement polymer chain structure model using an isothermal-isobaric ensemble (B30d), a simulation step of a preliminary replacement polymer chain structure model in a stretched state with tensile force (B30e), a simulation step of a preliminary replacement polymer chain structure model after release of tensile force (B30e'), a step of obtaining per-molecular interaction energy values ​​between polymer preliminary replacement chain structures in a stretched state (B30gs), a simulation step of a preliminary replacement polymer chain structure model in a molten state by annealing (B30f), a simulation step of a preliminary replacement polymer chain structure model after annealing (B30f'), and a step of obtaining per-molecular interaction energy values ​​between preliminary replacement polymer chain structures in a molten state (B30gm).

[0124] In the simulation box manufacturing step (B30a), a simulation box is manufactured to perform a simulation on the preliminary replacement polymer chain initial structure model obtained in the above step (B20c). In step (B30a), the simulation box is manufactured in the same manner as described in step (A20a), except that the repeating unit (1) and the repeating unit (3) containing a portion derived from the preliminary replacement monomer are used as repeating units. Therefore, the contents described in step (A20a) are applied identically to step (B30a).

[0125] After manufacturing the simulation box as described above, steps (B30b), (B30c), (B30d), (B30e), (B30e'), (B30gs), (B30f), (B30f'), and (B30gm) are performed in the same manner as steps (A20b), (A20c), (A20d), (A20e), (A20e'), (A20gs), (A20f), (A20f'), and (A20gm), respectively, except that they are performed on the preliminary alternative polymer chain initial structure model prepared in step (B30a); and thus, the matters described in steps (A20b), (A20c), (A20d), (A20e), (A20e'), (A20gs), (A20f), (A20f'), and (A20gm) are applied identically and are not repeated here.

[0126] Meanwhile, the reason for performing simulations using an isothermal-isobaric ensemble for the two states of the aramid polymer chain structure, the stretched state (the state in which it is manufactured into fibers) and the melted state (the fiber manufacturing process), is explained.

[0127] To manufacture high-performance aramid fibers, they must possess lower intermolecular interaction energies to become stable and exhibit superior physical properties compared to conventional fibers. Furthermore, for high-performance aramid fibers to be produced, the fibers must have higher intermolecular interaction energies during the manufacturing process to be unstable and facilitate processing.

[0128] Accordingly, the interaction energy values ​​per unit volume of the preliminary replacement polymer chain structure in the stretched and molten states are determined by simulations of the stretched and molten states in steps (B30gs) and (B30gm), respectively, and these values ​​are compared with the reference values ​​determined in steps (A20gs) and (A20gm) to select the final replacement monomer for the existing monomer used in the manufacture of conventional aramid fibers. Specifically, when the fiber is manufactured (stretched state), it must be in a stable state with lower interaction energy than the existing polymer chain structure, and during the fiber manufacturing process (molten state), it must be in an unstable state with higher interaction energy to allow for better dissolution than the existing polymer chain structure.

[0129] Therefore, the preliminary replacement monomer used in the preliminary replacement polymer chain structure, in which the interaction energy per volume of the stretched state of the preliminary replacement polymer chain structure is smaller than the reference value of step (A20gs) and the interaction energy per volume of the molten state of the preliminary replacement polymer chain structure is larger than the reference value of step (A20gm), is selected as the final replacement monomer for the existing monomer (i.e., 3,4'-ODA).

[0130] By the method of the present invention, monomers capable of producing aramid fibers with superior performance compared to existing aramid fibers are selected from a database of thousands to tens of thousands of items with high data throughput and / or high reliability.

[0131] Examples

[0132] The present invention will be described in detail below through examples.

[0133] Example 1

[0134] I. Determination of Reference Values ​​for Interaction Energy Per Volume in Extended and Molten States of Existing Polymer Chains Constituting Conventional Aramid Fibers

[0135] A. Determination of reference values ​​for interaction energy per unit volume in the stretched and molten states of polymer chains constituting Technora-aramid fibers

[0136] (A) Step for determining reference values ​​for interaction energy per unit volume in the stretched and molten states by simulation of a polymer chain structure model constituting Technora® aramid fibers (Step A)

[0137] Step (A10): Step for creating an initial structural model of the polymer chains constituting the technora fiber to be simulated.

[0138] SIMLE format files of TPC, PPD, and 3,4'-ODA monomers constituting Technora® aramid fibers were obtained from the PubChem chemical database (step (A10a)). Subsequently, from the SIMLE format (smi format) files of the TPC, PPD, and 3,4'-ODA monomers, information about the atoms constituting the monomers, including the partial charge, type of atom, and position value (coordinate value) of each atom constituting the monomer, was obtained in a mol2 format file (step (A10b)). In step (A10b), the monomer data information in SMILES format was input into the open source openbabel, and information about the monomers, including the partial charge value, type of atom, and position value (coordinate value) of the atoms constituting the monomers, was obtained in a mol2 format file by the Electronegativity Equalization Method (EEM). After that, in step (A10c), the list of atoms in the mol2 format information file obtained in step (A10b) was rearranged (reassigned) using the Antechamber program, and the reassigned mol2 format file was converted to an lt file format using code that converts mol2 format to an lt file.

[0139] Subsequently, the initial structure of the existing polymer chain for simulation was constructed by specifying a code in the Moltemplate to form aramid bonds between the monomers of TPC, PPD, and 3,4'-ODA in the above lt file format (step (A10d)).

[0140] Figures 4a and 4b show the monomer arrangement of TPC, PPD, and 3,4'-ODA made using Moltemplate from the lt file in step (A10d) (Figure 4a) and the arrangement of the initial polymer chain structure including the repeating units (1) and (2) (Figure 4b).

[0141] Step (A20): Determination of reference values ​​for inter-polymer chain interaction energies per unit volume of technoramid fibers by simulation

[0142] (Step (A20a): Create simulation box)

[0143] A simulation box was fabricated in Moltemplate using the initial polymer chain structure generated in the above step (A10d). The simulation box was configured with periodic boundaries, and the four repeating units (1) and four repeating units (2) formed a single polymer chain along the x-axis inside the boundaries. At this time, the order of combination of the repeating units (1) and repeating units (2) was random. Additionally, five polymer chains composed of the four repeating units (1) and four repeating units (2) were randomly placed along the y-axis and z-axis of the simulation box, respectively. The simulation box with the polymer chains placed therein is shown in Figures 5a and 5b. In the simulation box, the x-axis was adjusted to match the size of the chain composed of eight repeating units (i.e., four repeating units (1) and four repeating units (2)), and the y-axis and z-axis were fabricated with a size of 200 Å, with sufficient distance so that the polymer chains do not overlap.

[0144] (Phase (A20b): Stabilization Phase)

[0145] Subsequently, the existing polymer chain structure model placed in the simulation box fabricated in step (A20a) was stabilized using LAMMPS. Stabilization involved an acceptable energy and force of 1x10 -4 Kcal / mole and 1x10 -6 A stabilization simulation was performed by setting the value to Kcal / mole-Angstrom. If the tolerable energy and force of the polymer chain structure model placed in the simulation box fell below the aforementioned setting value, it was determined to be stabilized, and the next step was performed.

[0146] (Step (A20c): Simulation step by Barunframe Ensemble)

[0147] After step (A20b), simulation of the polymer chain structure model was performed using a straight frame ensemble (temperature 1K) until the interaction energy value between polymer chains converged to a constant value.

[0148] (Step (A20d): Simulation by isothermal-isobaric ensemble)

[0149] After step (A20c), the polymer chain structure model was simulated using an isothermal-isobaric ensemble at 298K and 1 bar until the interaction energy value between polymer chains converged to a constant value, thereby further stabilizing the polymer chain structure.

[0150] (Step (A20e): Simulation of elongated state)

[0151] After step (A20d), a tensile force was applied to the simulation box to stretch the polymer chain structure by 5% in the x-axis direction and simulated as an isothermal and isobaric ensemble at 298K and 1 bar for 50,000 fs (femtoseconds).

[0152] (Steps (A20e') and (A20gs): Simulation after release of tensile force and setting of reference values ​​for interaction energy between polymer chains per unit volume in the stretched state)

[0153] After step (A20e), the tensile force was released, and the existing polymer chain structure model was simulated at 298K and 1 bar using an isothermal-isobaric ensemble until it stabilized to a constant interaction energy value. The convergent interaction energy value was divided by the volume of the simulation box to obtain the interaction energy value per unit volume (reference value) of the stretched state of the existing polymer chain structure.

[0154] (Step (A20f): Simulation of molten state)

[0155] After step (A20d), the simulation was performed at an isostatic pressure of 1 bar for 50,000 fs while performing heat treatment by annealing, raising the simulation temperature to 3000 K and then lowering it to 298 K.

[0156] (Steps (A20f') and (A20gm): Simulation after annealing and setting reference values ​​for interaction energy per unit volume in the molten state)

[0157] After step (A20f), the existing polymer chain structure model was simulated at 298K and 1 bar using an isothermal and isobaric ensemble until it stabilized to a constant interaction energy value. The convergent interaction energy value was divided by the volume of the simulation box to obtain the interaction energy value per unit volume of the molten state of the existing polymer chain structure.

[0158] According to the above simulation, the value of the interaction energy per unit volume of the aramid chain structure constituting Technora® aramid fiber is -0.1918 Kcal / mole-Å. 3 (Elongated state) and -0.0888 Kcal / mole-Å 3 (Molten state) was obtained and is shown in the graph of Fig. 7.

[0159] Considering the error in the simulation, five simulations (steps (A20c), (A20d), (A20e), (A20e'), (A20f), and (A20f')) were performed for the same polymer chain structure with the initial velocity values ​​randomly varied to 38092034, 88888888, 12345678, 74684655, and 87464135 (random values ​​for the initial velocity). Among the interaction energy values ​​of the elongated and molten states obtained in each of the five simulations, the truncated average value excluding the maximum and minimum values ​​was used.

[0160] B. Measurement of interaction energy values ​​per unit volume in the stretched and molten states of polymer chains constituting PPTA aramid fibers

[0161] As described above, PPTA is an aramid fiber composed of the repeating unit (1) formed by the reaction of TPC and PPD. Accordingly, except that TPC and PPD monomers are used instead of TPC, PPD, and 3,4'-ODA, and a polymer chain containing the repeating unit (1) (a polymer chain consisting of 8 repeating units (1)) is used instead of the repeating units (1) and (2), the interaction energy values ​​per volume of the polymer chains constituting PPTA in the stretched and molten states were calculated in the same manner as described in item "A. Setting of reference values ​​for interaction energy per volume of polymer chains constituting Technora aramid fibers in the stretched and molten states" and are shown in FIG. 7. In addition, FIG. 6a and 6b show the arrangement of monomers constituting PPTA and the initial structural arrangement of polymer chains constituting PPTA.

[0162] II. Selection of Final Substitute Monomer (Step (B))

[0163] Step (B10): Monomer selection step based on filter criteria from chemical database

[0164] (Step (B10a): Step of obtaining raw monomer data by keyword search from a chemical database)

[0165] All monomers found by entering the keywords 'diamino', 'diamiline', 'bisaniline', 'aminophenoxy aniline', 'bis aminophenoxy', 'phenoxy propylamine', 'phenoxy ethylamine', 'naphthalenyloxy amine', 'bis ethanamine', 'bis propanamine', 'bis ethylamine', and 'bis propylamine', respectively, into the PubChem chemistry database were treated as raw monomer data. The total number of monomers found using each of the above keywords was 213,273. The searched monomers were provided in SMILE format in the PubChem chemistry database.

[0166] (Step (B10b): Selection step for monomers satisfying filter criteria from raw monomer data)

[0167] After that, preliminary replacement monomers were selected by applying the following filter criteria (1) to (4) to raw monomer data in SMILE format searched from the PubChem chemical database using code written in C++.

[0168] Filter criterion (1): Monomers with a molecular structure complexity value of 800 or less

[0169] Filter criterion (2): Uncharged monomer

[0170] Filter criterion (3): Monomers satisfying the angle (θ) between the center of the molecular structure of the monomer and the NH2 at both ends, -1 ≤ cosθ < 0

[0171] Filter criterion (4): Monomers with a radius of rotation of 6 Å or less from the central axis of the molecular structure of the monomer

[0172] A total of 8,965 monomers were selected based on the above filter criteria, including monomers such as [3-(aminomethyl)phenyl]methaneamine (SMILE format: C1=CC(=CC(=C1)CN)CN), 3-[5-(4-aminophenyl)-1H-1,2,4-triazole-3-yl]aniline (SMILE format: C1=CC(=CC(=C1)N)C2=NNC(=N2)C3=CC=C(C=C3)N), 4-[[4-[(4-aminophenyl)methyl]phenyl]methyl]aniline (SMILE format: C1=CC(=CC=C1CC2=CC=C(C=C2)N)CC3=CC=C(C=C3)N), and pyridine-2,6-diamine (SMILE format: C1=CC(=NC(=C1)N)N).

[0173] Step (B20): Step of constructing an initial structural model of the preliminary replacement polymer chain constituting the aramid fiber using the preliminary replacement monomer.

[0174] In step (B20a), monomer data in SMILE format for the monomers TPC and PPD constituting the technora and each of the 8,965 selected preliminary replacement monomers (replacing the 3,4'-ODA monomer) was input into the open-source openbabel, and information about the monomers, including partial charge values, types of atoms, and position values ​​(coordinate values) of the atoms constituting the monomers, was obtained in a mol2 format file by the Electronegativity Equalization Method (EEM). Then, in step (B20b), the list of atoms in the mol2 format information file obtained in step (B20a) was rearranged (reassigned) using the Antechamber program, and the reassigned mol2 format file was converted into an lt file format using code that converts the mol2 format to an lt file.

[0175] After that, in step (B20c), data in the lt file format for TPC, DDP, and each of the preliminary replacement monomers was entered into the Moltemplate, and the bonds between TPC and DDP and between TPC and one of the preliminary replacement monomers were specified to construct an initial structural model of a preliminary replacement polymer chain including repeating units (1) and (3) to be simulated. In repeating unit (3), the -HN-A-NH- portion is the part where the existing 3,4'-ODA monomer is replaced by the selected monomers. Specifically, since both 3,4'-ODA and the preliminary replacement monomer have -NH2, only the -A- portion in repeating unit (3) is changed.

[0176] [Repeat Unit 1]

[0177]

[0178] [Repeat Unit 3]

[0179]

[0180] (In the above repeating unit (3), the B portion is derived from the TPC monomer, and the -NH-A-NH- portion is derived from each preliminary replacement monomer selected in step (B10b).)

[0181] For example, when the preliminary replacement monomer is 3-[(4-aminophenyl)methyl]aniline), the initial structure of the preliminary replacement polymer chain is composed of the following repeating unit (1) and repeating unit (3a).

[0182] [Repeat Unit 1]

[0183]

[0184] [Repetition Unit 3a]

[0185]

[0186] For example, when the preliminary replacement monomer is [3-(aminomethyl)phenyl]methaneamine), the preliminary replacement polymer chain initial structure is composed of the following repeating unit (1) and repeating unit (3b).

[0187] [Repeat Unit 1]

[0188]

[0189] [Repeat Unit 3b]

[0190]

[0192] Step (B30): Selection of final replacement monomer by simulation

[0193] After fabricating a simulation box in Moltemplate using the initial structure of the preliminary replacement polymer chain prepared in step (B20c) (step (B30a)), the following steps were performed: stabilization step of the preliminary replacement polymer chain structure model (B30b), simulation step of the preliminary replacement polymer chain structure model using a straight frame ensemble (B30c), simulation step of the preliminary replacement polymer chain structure model using an isothermal-isobaric ensemble (B30d), simulation step of the preliminary replacement polymer chain structure model in an elongated state with tensile force applied (B30e), simulation step of the preliminary replacement polymer chain structure model after release of tensile force (B30e'), step of obtaining per-molecular interaction energy values ​​between the preliminary replacement polymer chains in an elongated state (B30gs), simulation step of the preliminary replacement polymer chain structure model in a molten state by annealing (B30f), simulation step of the preliminary replacement polymer chain structure model after annealing (B30f'), and step of obtaining per-molecular interaction energy values ​​between the preliminary replacement polymer chain structures in a molten state (B30gm).

[0194] Each of the above steps (B30a), (B30b), (B30c), (B30d), (B30e), (B30e'), (B30f), and (B30f') was performed in the same manner as steps (A20a), (A20b), (A20c), (A20d), (A20e), (A20e'), (A20f), and (A20f') of item “A. Determination of Reference Values ​​for Interaction Energy Per Volume of Polymer Chains Constituting Technora Aramid Fibers in Stretched and Molten States”, except that in step (B30a), a simulation was performed using a model of a preliminary replacement polymer chain structure prepared by placing the initial structure of the preliminary replacement polymer chain prepared in step (B20c) into a simulation box.

[0195] Subsequently, for each preliminary replacement polymer chain structure, the interaction energy value between the preliminary replacement polymer chains in the stretched state converging at (B30e') was divided by the volume of the simulation box to obtain the interaction energy value per volume in the stretched state between the preliminary replacement polymer chain structures containing the preliminary replacement monomer. Additionally, for each preliminary replacement polymer chain structure, the interaction energy value between the preliminary replacement polymer chains in the molten state converging at (B30f') was divided by the volume of the simulation box to obtain the interaction energy value per volume in the molten state between the preliminary replacement polymer chains containing the preliminary replacement monomer.

[0196] Considering the error in the simulation, five simulations (steps (B30c), (B30d), (B30e), (B30e'), (B30f), and (B30f')) were performed for the same aramid chain structure with the initial velocity values ​​randomly varied to 38092034, 88888888, 12345678, 74684655, and 87464135 (random values ​​for the initial velocity). Among the interaction energy values ​​of the elongated and molten states obtained in each of the five simulations, the truncated average value excluding the maximum and minimum values ​​was used.

[0197] The volume-wise interaction energy values ​​in the stretched state and the volume-wise interaction energy values ​​in the molten state of the preliminary replacement polymer chain structures, in which the 3,4'-ODA monomer was replaced by each of the 8,965 selected preliminary replacement monomers, were calculated, respectively, and the final replacement monomers were selected by comparing these values ​​with the reference values ​​for the stretched state and the molten state set in steps (A20gs) and (A20gm). That is, the volume-wise interaction energy in the stretched state obtained in step (B30gs) was -0.1918 Kcal / mole- obtained in step (A20gs). 3 It is smaller than, and the interaction energy per unit volume of the molten state obtained in the above step (B30 gm) is -0.0888 Kcal / mole-Å obtained in step (A20 gm). 3 The preliminary replacement monomer constituting a larger preliminary replacement polymer chain structure was selected as the final replacement monomer.

[0198] Figure 7 shows the interaction energy values ​​per unit volume in the stretched and molten states of the pre-replacement polymer chain structures, which were respectively replaced with the Technora, PPTA, and the 8,965 selected pre-replacement monomers obtained in Example 1. The pre-replacement monomer located in region ② of the graph in Figure 7 was finally selected as suitable for manufacturing aramid fibers with superior properties by being used as a replacement monomer for the 3,4'-ODA monomer in the existing Technora aramid fibers. Finally, 48 final replacement monomers were selected, and their types and interaction energy values ​​in the stretched and molten states are shown in Tables 1 and 2 below.

[0199] [Table 1] Interaction energy values ​​per unit volume of the selected final replacement monomers

[0200]

[0201] [Table 1 (continued)]

[0202]

[0203] [Table 2] IUPAC names and SMILES data for the 48 finally selected monomers

[0204]

[0205] [Table 2 (continued)]

[0206]

Claims

Claim 1 A method for screening monomers for manufacturing aramid fibers, performed by a computer device, comprising: a step (A) of determining a reference value for interaction energy per volume between existing polymer chains in an extended state and a molten state by simulation based on the molecular dynamics of existing polymer chains constituting the existing aramid fiber; a step (B10) of selecting preliminary replacement monomers from a chemical database according to filter criteria; a step (B20) of constructing an initial structural model of the preliminary replacement polymer chain constituting the aramid fiber using the preliminary replacement monomers; and a step (B30) of selecting a final replacement monomer by simulation based on the molecular dynamics of the structural model of the preliminary replacement polymer chain constituting the aramid fiber, wherein the step (B10) comprises a step (B10a) of obtaining raw monomer data by keyword search from a chemical database, and a step (B10b) of selecting preliminary replacement monomers from the raw monomer data that satisfy the following filter criteria (1) to (4). Filter criterion (1): a monomer having a molecular structural complexity value of 800 or less, filter criterion (2): a monomer having no charge, filter criterion (3): a monomer in which the angle (θ) formed by the center of the monomer’s molecular structure and the two terminal NH2s satisfies -1 ≤ cosθ < 0, and filter criterion (4): a monomer having a radius of rotation from the central axis of the monomer’s molecular structure of 6 Å or less. Claim 2 A method according to claim 1, wherein in step (A), the existing aramid fiber is poly-p-phenylene terephthalamide or Technora®. Claim 3 A method according to claim 1, wherein the step (B20) comprises: a step (B20a) of obtaining an information file for atoms constituting a preliminary replacement monomer from SMILE format data for a preliminary replacement monomer selected in step (B10b); a step (B20b) of converting the information file for atoms constituting a preliminary replacement monomer obtained in step (B20a) into an input format file for simulation progress; and a step (B20c) of constructing an initial structural model of a preliminary replacement polymer chain constituting an aramid fiber from the input format preliminary replacement monomer obtained in step (B20b). Claim 4 In paragraph 3, the above step (B30) comprises: a simulation box fabrication step (B30a) in which an initial structural model of the preliminary replacement polymer chain generated in step (B20c) is placed in the simulation box to construct a preliminary replacement polymer chain structural model (B30b); a stabilization step of the preliminary replacement polymer chain structural model using a straight frame ensemble (B30c); a simulation step of the preliminary replacement polymer chain structural model using an isothermal-isobaric ensemble (B30d); a simulation step of the preliminary replacement polymer chain structural model in which the preliminary replacement polymer chain structure is stretched along the x-axis by applying tensile force after step (B30d) (B30e); and a simulation step of the preliminary replacement polymer chain structural model using an isothermal-isobaric ensemble after releasing the tensile force after step (B30e) (B30e'). Step (B30gs) of calculating the interaction energy value per unit volume between the preliminary replacement polymer chains by dividing the interaction energy value between the convergent preliminary replacement polymer chains in the simulation of Step (B30e') by the volume of the simulation box, and using this as the interaction energy value per unit volume in the stretched state between the preliminary replacement polymer chains; after Step (B30d), a simulation step (B30f) of the preliminary replacement polymer chain structure model in the molten state by annealing; after Step (B30f), a simulation step (B30f') of the preliminary replacement polymer chain structure model using an isothermal-isobaric ensemble;A method comprising a step (B30gm) of calculating the interaction energy value per volume by dividing the interaction energy value between the convergent preliminary replacement polymer chains in the simulation of step (B30f') by the volume of the simulation box and using this as the interaction energy value per volume in the molten state between the preliminary replacement polymer chains, wherein the interaction energy value per volume in the stretched state between the preliminary replacement polymer chains in step (B30gs) is smaller than the reference value per volume interaction energy in the stretched state between the existing polymer chains in step (A), and the interaction energy value per volume in the molten state between the preliminary replacement polymer chains in step (B30gm) is larger than the reference value per volume interaction energy in the molten state between the existing polymer chains in step (A), and selecting a preliminary replacement monomer included in a preliminary replacement polymer chain structure model as the final replacement monomer. Claim 5 In paragraph 4, the method wherein the final substitute monomer is a substitute monomer for the 3,4'-diaminodiphenyl ether monomer of Technora. Claim 6 In claim 4, the selected final substitute monomer is 3-[(4-aminophenyl)methyl]aniline, 4-[[4-[(4-aminophenyl)methyl]phenyl]methyl]aniline, 4-[(Z)-N-[(Z)-1-(4-aminophenyl)ethylideneamino]-C-methylcarbomimidoyyl]aniline, 3-[4-(3-aminophenoxy)phenoxy]aniline, 3-[5-(4-aminophenyl)-1H-1,2,4-triazole-3-yl]aniline, 4-[[4-[(4-aminophenyl)methyl]phenyl]methyl]aniline, 4-[4-(4-aminophenoxy)-3-methylphenoxy]aniline, 3-[6-(3-aminophenoxy)pyridine-2-yl]oxyaniline, 4-[6-[5-(4-aminophenoxy)pyridine-2-yl]pyridine-3-yl]oxyaniline, 3-[4-[4-(3-aminophenoxy)phenyl]sulfanylphenoxy]aniline, 3-[2-(4-aminophenoxy)ethoxy]aniline, 3-[4-[(4-aminophenoxy)methyl]-2-methyl-1,3-dioxolane-2-yl]aniline, 4-[2-[4-(4-aminophenoxy)phenyl]ethyl]aniline, 3-[(3-aminophenoxy)methoxy]aniline, 3-(3-aminophenoxy)aniline, 3-[4-(4-aminophenoxy)phenoxy]aniline, 4-[4-[[4-(4-aminophenoxy)phenyl]diazenyl]phenoxy]aniline, Pyridine-2,6-diamine, pyrimidine-2,5-diamine, [3-(aminomethyl)phenyl]methaneamine, (1S,3R,4R)-4-fluorocyclopentan-1,3-diamine, 1,2-diamino-1,2,4-triazolidin-3-ol, 4-fluoropyridine-3,5-diamine, 2-N-methyl-1,3,5-triazine-2,4,6-triamine, 2,6-diaminopyridine-3-ol, 3-fluoropyridine-2,6-diamine, (2S,3R,6S)-3-amino-6-(aminomethyl)oxan-2-ol, 2H-triazine-1,5-diamine, 1,8-naphthylidine-2,7-diamine, 6-hydroxypyrazole[1,5-c]triazol-3,5-diamine, N,6-diamino-N-methylpyridine-2-carboxyimideamide, (1R)-1,5-diamino-2,3-dihydro-1H-indene-4-ol, 1,5-diamino-2,3-dihydro-1H-indene-4-ol, (1S)-1,5-diamino-2,3-dihydro-1H-indene-4-ol, (3R)-3,6-diamino-2,3-Dihydro-1-benzofuran-5-ol, 2,5-diamino-3-hydroxybenzoic acid, 4H-chromene-2,7-diamine, 4-[(4-aminophenyl)methyl]-2-methylaniline, 3-[(3-aminophenyl)diazenyl]aniline, 1,5-diaminonaphthalene-2-carboxylic acid, 3-amino-N-(3-aminophenyl)benzamide, 3-[4-[3-[4-(3-aminopropyl)phenoxy]propoxy]phenyl]propan-1-amine, 3-[4-(3-aminopropoxy)cyclohexyl]oxypropan-1-amine, 3-[4-[2-[4-(3-aminopropyl)phenoxy]ethoxy]phenyl]propan-1-amine, A method comprising monomers selected from 3-[6-(3-aminopropyl)pyridine-3-yl]propan-1-amine, 2-amino-1-[4-[4-(2-aminoacetyl)phenoxy]phenyl]ethanolone, 2-[3-[3-(2-aminoethoxy)phenyl]phenoxy]ethanolamine, and 2-[4-[2-[2-[2-[2-[4-(2-aminoethoxy)phenyl]ethoxy]ethoxy]ethoxy]ethyl]phenoxy]ethanolamine.

Images