KR102626369B1 - Circularly polarized light-responsive ferroelectric polymer and method of preparing thereof - Google Patents

Abstract

The present invention provides a new circularly polarized light-sensitive ferroelectric polymer structure and a method for manufacturing the same. The polymer structure has circular polarization sensitivity due to the helical structure of the conjugated polymer, and ferroelectric polymers are hierarchically coupled to the helical structure. In addition, the present invention provides a method of manufacturing the polymer structure by introducing a chiral transfer agent and a ferroelectric polymer using the self-assembly process of conjugated polymers, and the manufacturing method can be economically and easily performed through a solution process.

Description

Circularly polarized light-responsive ferroelectric polymer structure and method of manufacturing the same {CIRCULARLY POLARIZED LIGHT-RESPONSIVE FERROELECTRIC POLYMER AND METHOD OF PREPARING THEREOF}

The present invention relates to a ferroelectric polymer structure capable of responding to circularly polarized light.

The present invention relates to a method for manufacturing a ferroelectric polymer structure capable of responding to circularly polarized light.

When light travels straight, it vibrates and extends in all directions, including left and right, up and down, and light that travels in a spiral shape in a circle is called circularly polarized light. If the characteristic of circularly polarized light rotating in a specific direction is applied to the physical encryption of semiconductors, the number of combinations used to generate an encryption key can be increased without changing the physical size of the device, leading to physical duplication or hacking. It is possible to develop an encryption device with high security, which is difficult to achieve, and interest in its development is high due to recent security issues in the vulnerable Internet of Things (IoT).

Meanwhile, ferroelectric is a material that maintains the property of spontaneous polarization even without applying external electricity. Memory using such ferroelectric is a non-volatile memory that retains data even when the power is turned off, and is used in mobile devices that require low power consumption, IC cards without power, etc. It can be applied. Among organic materials, PVDF (Polyvinylidene Fluoride), a fluorine-based polymer, is a representative material with ferroelectricity. In the case of organic polymers, they are highly likely to be used in wearable devices due to their lightness and ability to change shape freely.

Accordingly, efforts have been made to develop new materials by introducing the above-described circular polarization sensitivity ability to ferroelectric polymers. However, it is difficult to form ferroelectric polymers into helical nanostructures capable of circular polarization sensitivity, and the production of existing nanostructures requires a chemical modification method. It takes a lot of time and money to do so, and since circularly polarized light-sensitive materials are made of a π-conjugated system with strong planarity, it is difficult to symmetry break them.

While researching a method for developing a new ferroelectric polymer capable of responding to circularly polarized light, the present inventors succeeded in developing a ferroelectric polymer structure with a hierarchical helical structure that can respond to circularly polarized light by applying the self-assembly properties of block copolymers. Thus, the present invention was completed.

Project identification number: SRFC-MA 1902-06

Name of department: Samsung Electronics Co., Ltd.

Name of project management (professional) organization: Samsung Future Technology Development Center

Research project name: Material technology business

Research project name: Research on homogeneous synthesis of multidimensional aqua nanoparticles based on in-situ self-assembly/polymerization using liquid transmission electron microscope e-beam

Contribution rate: 3/10

Name of project carrying out organization: Gwangju Institute of Science and Technology

Research period: 2021.01.01 ~ 2021.12.31

Korean Patent Publication No. 2020-0018590

The purpose of the present invention is to provide a ferroelectric polymer structure capable of sensitive to circularly polarized light and a method for manufacturing the same.

1. A block copolymer comprising a helically arranged conjugated diene first block and a second block bonded to the first block; And a ferroelectric polymer bonded to the second block.

2. The polymer structure of 1 above, wherein the first conjugated diene block includes a repeating unit derived from a 3-alkylthiophene monomer.

3. The polymer structure of 1 above, wherein the second block is bonded to both ends of the first block.

4. The polymer structure of 1 above, wherein the second block includes a repeating unit derived from an acrylate-based monomer.

5. The polymer structure according to 1 above, wherein the ferroelectric polymer contains vinyl isofluoride.

6. A method for producing a polymer structure comprising the step of self-assembling a block copolymer composed of a first conjugated diene block and a second block copolymerizable therewith in the presence of a chiral transfer agent and a ferroelectric polymer.

7. In item 6 above, the self-assembly is performed by adding a solvent with a low relative solubility to the block copolymer, a chiral transfer agent, and a ferroelectric polymer to a block copolymer solution containing a solvent with a high relative solubility to the block copolymer. A method of manufacturing a polymer structure, which is performed due to the difference in solubility of the two solvents.

8. In item 7 above, the block copolymer is poly(3-hexylthiophene)-b-poly(methyl methacrylate) (P3HT-b-PMMA), the solvent of the solution is tetrahydrofuran, and the low solubility solvent is n-butyl acetate, a method of producing a polymer structure.

9. The method of producing a polymer structure according to item 6 above, wherein the conjugated diene first block includes a repeating unit derived from a 3-alkylthiophene monomer.

10. The method of manufacturing a polymer structure according to item 6 above, wherein the second block includes a repeating unit derived from an acrylate-based monomer.

11. The method of manufacturing a polymer structure according to item 6 above, wherein the ferroelectric polymer contains vinyl isofluoride.

12. The method of producing a polymer structure according to 6 above, wherein the chiral transfer agent is limonene.

The polymer structure according to an embodiment of the present invention is a ferroelectric polymer capable of responding to circularly polarized light, and can be used as an optoelectronic device with increased encryption properties.

A ferroelectric polymer capable of responding to circularly polarized light can be manufactured through a polymer structure manufacturing method according to an embodiment of the present invention.

Figure 1 schematically shows a polymer structure according to an embodiment of the present invention.
Figure 2 shows the chemical formulas of PMMA and P[VDF-TrFE] and their interactions.
Figure 3 shows the chemical formulas of P3HT -b- PMMA and limonene.
Figure 4 is a photograph showing the appearance of a solution according to the ratio of mixed solvents according to an embodiment of the present invention.
Figure 5 shows absorption and emission spectra of wavelengths as the ratio of solvent with low solubility increases according to an embodiment of the present invention.
Figure 6 shows a TEM photograph and a schematic image of P3HT -b- PMMA self-assembled in each solvent according to an embodiment of the present invention.
Figure 7 shows a TEM photograph and a schematic image of P3HT -b- PMMA helically self-assembled through the addition of a chiral transfer agent according to an embodiment of the present invention.
Figure 8 shows the CD spectrum when a chiral transfer agent according to an embodiment of the present invention is added.
Figure 9 shows a CD spectrum when a chiral transfer agent and P(VDF-TrFE) according to an embodiment of the present invention are added.
Figure 10 shows a TEM photograph when a chiral transfer agent and P(VDF-TrFE) according to an embodiment of the present invention are added.
Figure 11 shows an FT-IR spectrum when a chiral transfer agent and P(VDF-TrFE) according to an embodiment of the present invention are added.

The present invention relates to a new circularly polarized light-sensitive ferroelectric polymer structure, which has circularly polarized light-sensitive ability due to the helical structure of a conjugated polymer, and the ferroelectric polymer is hierarchically bonded to the helical structure. In addition, the present invention provides a method of manufacturing the polymer structure by introducing a chiral transfer agent and a ferroelectric polymer based on the self-assembly process of conjugated polymers, and the manufacturing method can be performed through a solution process, so it has the advantage of being economical and convenient. there is.

Hereinafter, the present invention will be described in detail.

The present invention relates to a block copolymer comprising a first conjugated diene block arranged in a spiral and a second block bonded to the first block; and a ferroelectric polymer bonded to the second block.

The “conjugated diene first block” refers to a block composed of repeating units derived from a monomer containing a pair of conjugated double bonds. The block may be composed of repeating units derived from one monomer, or may be composed of multiple units. That is, the first conjugated diene block is a conjugated block, and is characterized by semiconductor electrical conductivity and absorption and emission in the visible light range due to a repeating structure of double bonds and single bonds. For example, the conjugated diene first block is P3AT (poly(3-alkylthiophene)), PBTTT (poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno(3,2-b)thiophene), P3BT (Poly(3-butylthiophene-2,5-diyl)), F8BT (poly(9,9-dioctylfluorene-cobenzothiadiazole)) or DPP2T-TT (poly(diketopyrrolopyrrole-co-thiopheneco-thieno[3,2-b]thiophene -cothiophene)), preferably P3HT (poly(3-hexylthiophene-2,5-diyl)).

The “second block” is used to mediate the bond between the first block and the ferroelectric polymer, and is not particularly limited as long as it forms a copolymer with the first block and can be bonded to the ferroelectric polymer.

The “bonding with a ferroelectric polymer” includes non-covalent interactions. For example, when the ferroelectric polymer is a polymer containing polyvinylidene fluoride (PVDF), the second block contains one repeating unit derived from an acrylate-based monomer that can form a hydrogen bond and dipole interaction with the ferroelectric polymer. Or, it may include a plurality. For example, the block copolymer may be P3HT -b- poly(acrylic acid) (P3HT -b- PAA), P3HT -b- poly(methyl methacrylate) (P3HT -b- PMMA), and P3HT -b- PMMA. The interaction between and P(VDF-TrFE) is schematized as shown in Figure 2.

The “spiral arrangement” means that the structure of the nanofibers in which the first block is stacked rotates and advances in a spiral shape, and the structure is shown in detail in FIG. 1. At this time, as described above, the second block and the ferroelectric polymer are bonded to each first block and arranged regularly, so that the polymer structure as a whole forms a hierarchical helical array. The helical structure may be a helical structure that rotates to the left (M-helix) or a helical structure that rotates to the right (R-helix).

The second block may be coupled to both ends of the first block as shown in FIG. 1.

The polymer structure of the present invention can respond to circularly polarized light due to the helical structure, and the effect was confirmed in detail in the examples described later.

The circularly polarized light is a type of polarized light and means that the end of the vibration vector of a light wave moves circularly (spiral motion when considering the progress of light). Circular polarization that is clockwise (counterclockwise) as seen from an observer facing the direction of circular polarization is called right-handed (left-handed) circular polarization. Circular polarization has the advantage of expanding the application range of light, and therefore polymers capable of responding to circular polarization have increased encryption properties and can be used in memory devices that require high security.

The ferroelectric polymer refers to a polymer that has ferroelectricity and has a spontaneous polarization phenomenon in which positive and negative charges are spontaneously split in an insulator or dielectric without external electrical stimulation. For example, the ferroelectric polymer may include polyvinylidene fluoride (PVDF), for example, PVDF, P(VDF-TrFE), or P(VDF-TrFE-CFE).

Specifically, the PVDF is known to have at least four phases, such as α-, β-, γ-, and δ-phase, where the α phase is non-polar and the other three are polar phases, of which the β phase is the most active. It exhibits high polarization and the most advantageous ferroelectric properties. P(VDF-TrFE), which is a copolymerization of PVDF with trifluoroethylene (TrFE), has the advantage of allowing the β phase to occur more easily than PVDF.

In addition, the present invention relates to a method for producing a polymer structure comprising the step of self-assembling a block copolymer composed of a conjugated diene first block and a second block copolymerizable therewith in the presence of a chiral transfer agent and a ferroelectric polymer.

The conjugated diene first block, the second block copolymerizable therewith, and the ferroelectric polymer are omitted to avoid overlap with the above-mentioned information. That is, in the present invention, the conjugated diene first block includes a repeating unit derived from a 3-alkylthiophene monomer, the second block includes a repeating unit derived from an acrylate-based monomer, or the ferroelectric polymer is an isoelectric polymer. A method for producing a polymer structure comprising vinyl fluoride is included.

Because the block copolymer has self-assembly properties, nanofiber structures can be created by self-assembly method. Self-assembly, as its linguistic meaning implies, refers to the phenomenon of self-arrangement in a certain manner due to local interactions between the material and its surroundings without the intervention of external forces. In the case of conjugated polymers, self-assembly occurs due to π-π stacking interaction between molecules. This is possible.

In the present invention, a polymer structure forming a hierarchical helical structure was manufactured by performing the above self-assembly in the presence of a chiral transfer agent and a ferroelectric polymer.

The chiral transfer agent refers to a transfer agent that introduces chirality by acting on a non-chiral conjugated polymer to form a helical structure, and has an inductive effect when the block copolymer is stacked. effect) to cause chiral transfer.

The chiral transfer is not particularly limited as long as it can be appropriately selected by a person skilled in the art considering the interaction with the block copolymer used. For example, when the block copolymer is P3HT -b- PMMA, the chiral transfer agent is It may be limonene, and limonene may be added to the solvent in the solution process to cause P3HT -b- PMMA to form a helical structure rotating in the right or left direction. Figure 3 shows the chemical formulas of P3HT -b- PMMA and limonene.

The self-assembly involves mixing a block copolymer solution containing a solvent (good solvent) with high relative solubility to the block copolymer, a solvent (poor solvent) with low relative solubility to the block copolymer, a chiral transfer agent, and a ferroelectric polymer. The addition may be performed due to the difference in solubility of the two solvents.

The selection of the two solvents considering the difference in solubility can be appropriately selected by a person skilled in the art. Specifically, in the embodiments of the present invention, the good solvent and the poor solvent are Hansen solubility parameters. It was decided based on . For example, THF, a solvent with relatively high solubility for the block copolymer P3HT-b-PMMA used, was selected as a good solvent, and n-BuOAc, a solvent with relatively low solubility for P3HT-b-PMMA, was selected as a poor solvent. was selected as solvent. When n-BuOAc, a poor solvent, is added to a solution in which P3HT-b-PMMA is dissolved in THF, a good solvent, π-π stacking interaction of P3HT blocks can be induced due to the difference in solubility of the two solvents, thereby forming a polymer structure. can be formed.

For example, when the block copolymer is P3HT -b- PMMA, the high solubility solvent may be selected from chloroform, tetrahydrofuran, chlorobenzene group, and bromobenzene group, and the low solubility solvent may be methanol and isopropanol. (IPA), acetonitrile, n-butyl acetate, or ethanol, preferably tetrohydrofuran and n-butyl acetate, respectively.

At this time, the crystallinity of the formed nanostructure can be controlled depending on the ratio of the two solvents used, and the related experimental results are described later in the Examples.

The ferroelectric polymer may be added together with a chiral transfer agent, and may be regularly arranged in the helical structure that becomes a template for the polymer structure by combining with the second block of the block copolymer described above.

After the above process, the solvent can be removed through an appropriate method that can be selected by a person skilled in the art, such as natural drying or heat treatment.

Hereinafter, the present invention will be described in detail with reference to examples.

Example

1. Crystallization-based P3HT -b- Self-assembly of PMMA

A nanotemplate was formed using self-assembly of conjugated polymers. The block copolymer used in this example was PH3T -b- PMMA, and a solution was prepared using THF, which has high solubility for PH3T -b- PMMA, as a solvent, and then using a solvent with low solubility for PH3T -b- PMMA. Nanowire polymer structures were formed by adding n-BuOAc in various ratios.

P3HT- b -PMMA was placed in THF and sonicated at room temperature to prepare a completely dissolved P3HT- b -PMMA solution with a concentration of 5 mg/mL. THF and n-BuOAc were added in order to 50 μL of the previously prepared P3HT- b -PMMA solution so that THF and n-BuOAc had volume ratios of 9:1, 7:3, 5:5, 3:7, and 1:9, respectively. Added. A nanowire polymer structure was formed through aging for 12 hours. At this time, the final concentration of the prepared P3HT- b -PMMA solution was fixed at 0.5 mg/mL.

In this step, longer nanostructures can be formed by increasing the ratio of solvents with low solubility to PH3T -b- PMMA. In Figure 4, the color of each solution changes to purple over time. The solution with a low proportion of solvents with low solubility appears orange, and the solution with a high proportion of solvents with low solubility appears purple. The aggregation of the nanostructures can be visually confirmed, and in Figure 5, it was confirmed that as the ratio of solvent with low solubility increases, the nanostructures become more agglomerated, red shift occurs, and quenching occurs. In Figure 6, the extension of the length of the nanostructure is shown for each ratio of solvent used.

2. Formation of hierarchical helical structure through addition of chiral transfer agent and ferroelectric polymer

The block copolymer used was PH3T -b- PMMA, and the solution was prepared using THF, which has high solubility for PH3T -b- PMMA, as a solvent, followed by n-BuOAc and n-BuOAc, which have low solubility for PH3T -b- PMMA. A chiral transfer agent and ferroelectric polymer were added. [S]-[-]-limonene and [R]-[-]-limonene were used as chiral transfer agents, and P(VDF-TrFE) was used as a ferroelectric polymer. Afterwards, the solvent was removed through natural drying.

P3HT- b -PMMA was placed in THF and sonicated at room temperature to prepare a completely dissolved P3HT- b -PMMA solution with a concentration of 5 mg/mL. Add [S]-[-]-limonene or [R]-[-]-limonene to 50 μL of the P3HT- b -PMMA solution prepared previously so that the molar ratio of P3HT- b -PMMA and limonene is 1:4600. did. Next, n-BuOAc was added to the two solutions containing [S]-[-]-limonene or [R]-[-]-limonene so that THF and n-BuOAc had a volume ratio of 1:9. A helical polymer structure was formed through aging for 12 hours. At this time, the final concentration of the prepared P3HT- b -PMMA solution was 0.5 mg/mL. Additionally, P(VDF-TrFE) was dissolved in THF to prepare a ferroelectric polymer solution with a concentration of 5 mg/mL. 5 mg/mL of P(VDF-TrFE) solution was added to the P3HT- b -PMMA solution in which the helical polymer structure was formed so that the molar ratio of P3HT- b -PMMA and P(VDF-TrFE) was 4:1. A hierarchical helical polymer structure was formed through aging for 6 hours.

In Figure 7, it is shown through TEM images and schematic drawings that the achiral conjugated polymer forms a helical structure in the right or left direction through the addition of a chiral transfer agent.

In Figure 8, it was confirmed through the CD spectrum analysis results that helical nanostructures showing opposite directions were formed by introducing a chiral transfer agent into PH3T -b- PMMA.

Figures 9 and 10 show CD spectrum analysis results and TEM images when a chiral transfer agent and P(VDF-TrFE) were introduced. Figure 11 shows the FT-IR spectrum results, confirming that upon addition of P(VDF-TrFE), PH3T -b- PMMA formed hydrogen bonds and dipole interactions with P(VDF-TrFE) through the PMMA portion.

Claims (12)

A block copolymer comprising a first conjugated diene block arranged in a spiral and a second block bonded to the first block; and a ferroelectric polymer coupled to the second block and arranged in a spiral along the first block.
In claim 1,
A polymer structure in which the first conjugated diene block includes a repeating unit derived from a 3-alkylthiophene monomer.
In claim 1,
The second block is a polymer structure bonded to both ends of the first block.
In claim 1,
The second block is a polymer structure comprising a repeating unit derived from an acrylate-based monomer.
In claim 1,
A polymer structure wherein the ferroelectric polymer includes vinyl isofluoride.
It includes the step of self-assembling a block copolymer composed of a conjugated diene first block and a second block copolymerizable therewith in the presence of a chiral transfer agent and a ferroelectric polymer,
The first block is arranged in a spiral,
A method of manufacturing a polymer structure in which the ferroelectric polymer is combined with a second block and arranged in a spiral along the first block.
In claim 6,
The self-assembly is achieved by adding a solvent, a chiral transfer agent, and a ferroelectric polymer with a relatively low solubility to the block copolymer to a block copolymer solution containing a solvent with a high relative solubility to the block copolymer, due to the difference in solubility of the two solvents. A method for manufacturing a polymer structure, which is performed.
In claim 7,
The block copolymer is poly(3-hexylthiophene)-b-poly(methyl methacrylate) (P3HT-b-PMMA), the solvent of the solution is tetrahydrofuran, and the low solubility solvent is n-butyl acetate, Method for manufacturing polymer structures.
In claim 6,
A method of producing a polymer structure, wherein the conjugated diene first block includes a repeating unit derived from a 3-alkylthiophene monomer.
In claim 6,
A method of producing a polymer structure, wherein the second block includes a repeating unit derived from an acrylate-based monomer.
In claim 6,
A method of manufacturing a polymer structure, wherein the ferroelectric polymer includes vinyl isofluoride.
In claim 6,
A method for producing a polymer structure, wherein the chiral transfer agent is limonene.