CN110120249B - A method for constructing a target structure through targeted regulation of kinetic pathways - Google Patents

Abstract

The invention belongs to the technical field of high polymer materials, and particularly relates to a method for constructing a target structure through a targeted regulation and control kinetic path. The method utilizes a rearrangement transformation mechanism of the rigid-flexible block polymer, accurately positions the parameters of the rearrangement transformation process, and constructs a rigid-flexible block polymer target structure through completely targeted regulation and control of a kinetic path; the chord method is introduced to calculate the minimum rearrangement transition energy path between two structures, namely the rearrangement transition energy path of the target structure existing as a metastable state. The invention successfully constructs a dynamic formation path of a target structure in a rigid-flexible block polymer system, and has high practical application value; a reverse kinetic path design strategy is developed, and the problem that a target structure cannot be constructed in a targeted mode at present is solved.

Description

A method for constructing a target structure through targeted regulation of kinetic pathways

technical field

The invention belongs to the technical field of polymer materials, and in particular relates to a method for constructing various target structures of rigid-flexible block polymers through targeted regulation of dynamic pathways.

Background technique

Many polymer systems in practical applications have a certain degree of rigidity, and have great application value in many fields, including light-emitting diodes (LEDs), polymer solar cells, etc. Therefore, the targeted structure of polymers containing rigid chain blocks research has attracted more and more attention. It is a block polymer system formed by connecting two different rigid and flexible blocks by chemical bonds. It has a large size asymmetry effect, and there is a strong anisotropic orientation interaction between the rigid blocks. Compared with the theoretical study of the self-assembly behavior of flexible block polymers, the progress of block polymers with rigid chains has been slow due to their complex structures and vast parameter spaces.

Most of the theories that study the relationship between material structure and performance are based on the thermodynamic equilibrium state. However, the self-assembly behavior in real systems is very complex, and the properties required by these materials will inevitably involve non-equilibrium states. Phase transition kinetics It often becomes a key factor in determining the final performance of the material. Usually, in the free energy scenario, the free energy difference between different metastable structures is often small, and weak perturbations may induce phase structure transitions, so these complex metastable states are often observed experimentally structure.

At present, the theory of phase transition kinetics of rigid-flexible block polymer systems is still in the initial stage of development. It can only realize the construction of a single continuous network structure under the conditions of epitaxial growth and certain specific parameters, and it cannot be accurately positioned and selected. range of parameters and build various target structures. Therefore, how to use the abundant metastable resources to achieve targeted construction of various target structures and accurately locate the parameter positions has become an urgent problem to be solved.

Contents of the invention

The main purpose of the present invention is to provide a method for constructing a target structure of a rigid-soft block polymer by using the rearrangement transformation mechanism of a rigid-soft block polymer, so as to solve the problem that the target structure cannot be constructed at present.

The method for constructing the target structure of the rigid-soft block polymer proposed by the present invention is to use the rearrangement transformation mechanism of the rigid-soft block polymer to accurately locate the parameters of the rearrangement transformation process, and to construct Rigid-flexible block polymer target structure. Specific steps are as follows:

相图； (1) The rigid-flexible block polymer system is calculated by self-consistent mean field theory (SCFT).

Phase Diagrams;

(2) Determine the target structure of the targeted structural rigid-flexible block polymer;

(3) Analyze the relative position of the target structure in the phase diagram of the system, determine the parameters of the rearrangement transformation process of the rigid-soft block polymer, and select the parameter area for the rearrangement transformation;

(4) Analyze the space symmetry group and reciprocal lattice vector of the target structure, and construct a rigid-soft block polymer simple layer and column structure that matches the symmetry in the selected parameter region;

(5) Bring the rigid-flexible block polymer simple layer and column structure with different orientations into SCFT, change the unit cell size, and perform multiple sets of iterative operations, and use the simple layer and column structure with the lowest free energy as final steady-state structure;

(6) The two final stable structures are used as the two endpoints of the string, and the minimum rearrangement transition energy path between the two structures is calculated by applying the string method, that is, the rearrangement transition energy path in which the target structure exists as a metastable state .

In step (2) of the present invention, the target structure mainly includes the following types: complex network structure, including single continuous network structure and perforated layered phase structure, etc.; columnar phase structure, spherical phase structure, etc.

In step (3) of the present invention, different parameter areas are determined according to different target structures, specifically as follows:

If the target structure is a complex network structure, select the layered phase (or columnar phase) parameter area near the phase transition point of disordered phase-layered phase (or columnar phase);

If the target structure is columnar phase, the layered phase near the columnar phase-layered phase transition point is selected as the parameter area where the steady state occurs;

If the target structure is a spherical phase, the columnar phase near the spherical phase-columnar phase transition point is selected as the parameter area where the steady state occurs.

In the method of the invention, the dynamic formation path of the target structure in the rigid-flexible block polymer system is successfully constructed, which has high practical application value. The reverse kinetic pathway design strategy was developed to solve the problem that the target structure cannot be targeted at present.

Description of drawings

Figure 1 is a schematic diagram of the specific process of adjusting the dynamic path by accurately positioning the parameters of the rearrangement transformation process to realize the targeted construction of various target structures of rigid-flexible block polymers.

相图。Figure 2 shows the structure of rigid-flexible block polymers under low orientation interaction and low size asymmetry

Phase Diagrams.

Figure 3 is an example of the targeted structure achieved through rearrangement transitions between different orientation layers when the target structure of the rigid-flexible block polymer is a single continuous network structure. The illustration shows the relative positions of the selected parameters in the phase diagram.

Figure 4 is an example of the targeted structure achieved by rearrangement transformation between different orientation layers when the target structure of the rigid-flexible block polymer is a columnar phase, and the illustration shows the relative positions of the selected parameters in the phase diagram.

Figure 5 is an example of the targeted structure achieved by rearrangement transformation between different orientation columns when the target structure of the rigid-flexible block polymer is a perforated layered phase. The inset shows the relative positions of the selected parameters in the phase diagram.

Figure 6 is an example of the targeted structure achieved by rearrangement transitions between columns of different orientations when the target structure of the rigid-flexible block polymer is a spherical phase, and the inset shows the relative positions of the selected parameters in the phase diagram.

detailed description

In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be further described below with examples, but the protection scope of the present invention is not limited to the examples. Other changes and modifications made by those skilled in the art without departing from the spirit and protection scope of the present invention are also included in the protection scope of the present invention.

Fig. 1 is a schematic diagram of the process of regulating the dynamic pathway to realize the targeted structure of the rigid-soft block polymer target structure, and all the embodiments are based on this process.

Example 1

(1) Determine the parameter range of rearrangement transformation

。 First obtain the phase diagram of the rigid-soft block polymer system by SCFT calculation, as shown in Figure 2, determine that the target structure of the targeted structure rigid-soft block polymer is a single continuous network structure; according to the single continuous network in the present invention The relationship between structure and parameter range selection, the selected parameter area is near the phase transition point of disordered phase-layered phase, as shown in the illustration of Figure 3, the position of the circle point (blue point), specifically

.

(2) Build a layer and column structure consistent with the symmetry of the target structure

Since the target structure in this example is a single continuous network structure Single Gyroid, its reciprocal lattice vector is the {110} crystal plane family, so in real space, layer structures of {110} crystal plane families with different orientations are constructed.

(3) Determine the optimal unit cell size

为单位）。 Bring the constructed {110} crystal plane family layers with different orientations into SCFT, change the size of the unit cell, perform multiple sets of iterative operations, find the phase structure with the lowest corresponding free energy, and determine the optimal unit cell size here is 3.6*3.6*3.6 (based on mean square end distance

as the unit).

(4) Calculate the minimum energy path

Taking the {110} crystal plane family layers of different orientations with a unit cell size of 3.6*3.6*3.6 as the two endpoints of the string, and applying the string method to calculate, the minimum rearrangement transformation energy path is obtained, as shown in Figure 3, the single The continuous network structure realizes the targeted construction of the target structure.

Example 2

(1) Determine the parameter range of rearrangement transformation

。 First, the phase diagram of the rigid-flexible block polymer system is obtained by SCFT calculation, as shown in Figure 2, it is determined that the target structure of the targeted structure rigid-soft block polymer is a quadrangular columnar phase; according to the quadrangular columnar phase and The relationship between parameter range selection, select the parameter area near the columnar phase-lamellar phase transition point, as shown in the illustration of Figure 4, the position of the circle point (blue point), specifically

.

(2) Build a layer and column structure consistent with the symmetry of the target structure

Since the target structure in this embodiment is a quadrangular columnar phase, its reciprocal lattice vector is the {110} crystal plane family, so in real space, layer structures of the {110} crystal plane family with different orientations are constructed.

(3) Determine the optimal unit cell size

为单位）。 Bring the constructed {110} crystal plane family layers with different orientations into SCFT, change the size of the unit cell, perform multiple sets of iterative operations, find the phase structure with the lowest corresponding free energy, and determine the optimal unit cell size here is 4*4*4 (with mean square end distance

as the unit).

(4) Calculate the minimum energy path

Taking the {110} crystal plane family layers with different orientations of unit cell size 4*4*4 as the two endpoints of the string, and applying the string method to calculate, the minimum rearrangement transformation energy path is obtained, as shown in Figure 4, there are four corners in the path The columnar phase realizes the targeted structure of the target structure.

Example 3

(1) Determine the parameter range of rearrangement transformation

。 First, the phase diagram of the rigid-soft block polymer system is obtained through SCFT calculation, as shown in Figure 2, it is determined that the target structure of the targeted structure rigid-soft block polymer is a perforated layered phase; according to the perforated layered phase in the present invention The relationship between the phase (complex network structure) and the selection of the parameter range, the selected parameter area is near the phase transition point of the disordered phase-column, as shown in the illustration of Figure 5, the position of the circle point (blue point), specifically

.

(2) Construct a layer and column structure consistent with the symmetry of the target structure.

Since the target structure in this embodiment is a perforated layered phase, its reciprocal lattice vector is the <111> crystal orientation family, so in real space, <111> crystal orientation family columns with different orientations are constructed.

(3) Determine the optimal unit cell size

为单位）。 Bring the <111> oriented column with different orientations into SCFT, change the size of the unit cell, and perform multiple sets of iterative calculations to find the phase structure with the lowest corresponding free energy, and determine the optimal unit cell size here is 3.6*3.6*3.6 (based on mean square end distance

as the unit).

(4) Calculate the minimum energy path

Using the <111> orientation group columns with a unit cell size of 3.6*3.6*3.6 as the two endpoints of the string, the calculation of the string method is used to obtain the minimum rearrangement transition energy path, as shown in Figure 5. There are perforations in the path Layered phase, which realizes the targeted construction of the target structure.

Example 4

(1) Determine the parameter range of rearrangement transformation

。 First, the phase diagram of the rigid-soft block polymer system is obtained by SCFT calculation, as shown in Figure 2, it is determined that the target structure of the targeted structure rigid-soft block polymer is a body-centered cubic spherical phase; according to the spherical phase of the present invention In relation to the selection of the parameter range, the selected parameter area is near the spherical phase-column phase transition point, as shown in the illustration of Figure 6, the position of the circle point (blue point), specifically

.

(2) Build a layer and column structure consistent with the symmetry of the target structure

Since the target structure in this example is a body-centered cubic spherical phase, its reciprocal lattice vector is the <111> crystal orientation family, so in real space, <111> crystal orientation family columns with different orientations are constructed.

(3) Determine the optimal unit cell size

为单位）。 Bring the <111> oriented column with different orientations into SCFT, change the size of the unit cell, and perform multiple sets of iterative calculations to find the phase structure with the lowest corresponding free energy, and determine the optimal unit cell size here is 3.6*3.6*3.6 (based on mean square end distance

as the unit).

(4) Calculate the minimum energy path

Using the <111> orientation group columns with a unit cell size of 3.6*3.6*3.6 as the two endpoints of the string, the calculation of the string method is used to obtain the minimum rearrangement transition energy path, as shown in Figure 6, where bulk The center-cubic spherical phase realizes the targeted structure of the target structure.

Claims (3)

1. A method for constructing a target structure through targeted regulation of dynamic pathways, characterized in that the rearrangement transformation mechanism of rigid-flexible block polymers is used to accurately locate the parameters of the rearrangement transformation process, and through complete targeting Adjust the dynamic path and construct the rigid-soft block polymer target structure; the specific steps are as follows: (1) The rigid-flexible block polymer system is calculated by the self-consistent mean field theory SCFT

Phase Diagrams; (2) Determine the target structure of the targeted structural rigid-flexible block polymer; (3) Analyze the relative position of the target structure in the phase diagram, determine the parameters of the rigid-soft block polymer rearrangement transformation process, and select the parameter area for the rearrangement transformation; (4) Analyze the space symmetry group and reciprocal lattice vector of the target structure, and construct a rigid-soft block polymer simple layer and column structure that matches the symmetry in the selected parameter region; (5) Bring the rigid-flexible block polymer simple layer and column structure with different orientations into SCFT, change the unit cell size, and perform multiple sets of iterative operations, and use the simple layer and column structure with the lowest free energy as final steady-state structure; (6) The two final stable structures are used as the two endpoints of the string, and the minimum rearrangement transition energy path between the two structures is calculated by applying the string method, that is, the rearrangement transition energy path in which the target structure exists as a metastable state . 2. The method according to claim 1, wherein the target structure in step (2) mainly includes the following types: complex network structure, columnar phase structure and spherical phase structure; wherein, the complex network structure includes single Continuous network structure and perforated layered phase structure. 3. The method according to claim 2, wherein in step (3), the parameter area is selected according to different target structures, specifically as follows: If the target structure is a complex network structure, select the layered phase or columnar phase parameter area near the transition point of disordered phase-layered phase or columnar phase; If the target structure is columnar phase, the layered phase near the columnar phase-layered phase transition point is selected as the parameter area where the steady state occurs; If the target structure is a spherical phase, the columnar phase near the spherical phase-columnar phase transition point is selected as the parameter area where the steady state occurs.

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