Chiral P (VDF-TrFE-CFE)-based quaternary block ferroelectric polymer material and preparation method thereof

Abstract

The invention discloses a chiral P (VDF-TrFE-CFE)-based quaternary block ferroelectric polymer material and a preparation method thereof, and belongs to the field of novel functional polymer materials. Chiral small molecules are added into a P (VDF-TrFE-CFE) solution, the chiral small molecules and a CFE unit are subjected to a chemical reaction to form a new ME block, and then a quaternary block polymer (PVDF-TrFE-CFE-ME) is induced to form chirality. Chirality and ferroelectricity are combined, and chiral components are introduced into a ferroelectric polymer block for the first time, so that the chiral PVDF-based polymer is obtained. The possibility of crystallization of the ferroelectric polymer in a polar point group is increased, and the potential application of the ferroelectric polymer in the optical aspect is widened.

Description

(I) Technical Field:

[0001] This invention belongs to the field of novel functional polymer materials technology, and relates to a chiral quaternary ferroelectric block polymer material based on poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (PVDF-TrFE-CFE) and its preparation method, namely a chiral P(VDF-TrFE-CFE)-based quaternary block ferroelectric polymer material and its preparation method. (II) Background Technology:

[0002] Ferroelectric materials are a class of insulators with spontaneous polarization intensity that can be reoriented by an applied electric field. Ferroelectric materials exhibit the strongest piezoelectricity among known piezoelectric materials and are widely used in high-dielectric-constant capacitors, non-volatile memories, and optoelectronic devices.

[0003] Inorganic ferroelectric materials possess high ferroelectric properties, but they require high processing temperatures and exhibit poor flexibility. The ferroelectricity of polymers was first discovered in polyvinylidene fluoride (PVDF). Subsequently, its binary copolymers, such as poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) and terpolymers, such as poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (PVDF-TrFE-CFE), have gradually replaced inorganic materials in many electrical and optical applications due to their solution processability, low weight and cost, high flexibility and biocompatibility, and high polarization activity. These materials are used in commercial products such as wearable flexible sensors, medical imaging, underwater navigation, soft robots, and actuators.

[0004] Chirality is closely related to the rules of life and exists in many natural macromolecules, such as proteins, polysaccharides, and nucleic acids. The synthesis of chiral substances, especially chiral polymers, is one of the most popular problems in materials science and chemistry. The ferroelectricity of materials stems from the asymmetry of their crystal structure, and the asymmetry caused by chirality can increase the likelihood of ferroelectric materials crystallizing in polar point groups, thereby enhancing their ferroelectric properties. Furthermore, chiral materials themselves possess circular dichroism and circularly polarized luminescence properties. Combining chiral materials with ferroelectric materials can extend their applications to the optical field, such as optical sensors, enantiomer separation, ferroelectric liquid crystals, asymmetric catalysis, and 3D optical displays. These chirality-related chemical design strategies can promote the development of chiral synthesis, thus greatly enriching the content of ferroelectric chemistry. However, currently, among the three major ferroelectric material systems—inorganic ferroelectrics, molecular ferroelectrics, and polymer ferroelectrics—only molecular ferroelectrics possess chirality.

[0005] Since chirality exists only in organic compounds, how to prepare a chiral ferroelectric polymer and thus expand its applications in ferroelectric and optical fields is a major challenge. (III) Summary of the Invention:

[0006] The purpose of this invention is to provide a chiral P(VDF-TrFE-CFE)-based quaternary block ferroelectric polymer material and its preparation method, aiming to solve the problems existing in current ferroelectric polymers. The chiral ferroelectric polymer of this invention is obtained by chemically reacting chiral small molecules with P(VDF-TrFE-CFE) to form new blocks (MEs), and exhibits chirality corresponding to the chiral small molecules. This material is the first PVDF-based polymer that combines ferroelectricity and chirality. The synthesis steps of this invention are short and the preparation process is simple, requiring only one step at room temperature.

[0007] The technical solution of the present invention is a chiral P(VDF-TrFE-CFE)-based quaternary block ferroelectric polymer material, which is formed by the chemical reaction of chiral small molecules with P(VDF-TrFE-CFE) to form new blocks (MEs) and exhibits chirality corresponding to the chiral small molecules.

[0008] The molar content of ME blocks in the chiral ferroelectric polymer increases with increasing reaction time, but does not exceed 5%; the color of the chiral ferroelectric polymer deepens with increasing molar content of ME blocks, gradually changing from light yellow to dark yellow.

[0009] The chiral small molecules include, but are not limited to, chiral amine small molecules (R / S)-2-amino-1-phenylethanol, (R / S)-1-(4-bromophenyl)ethylamine, (R / S)-N-benzyl-1-phenylethylamine, (R / S)-α-methylbenzylamine, (R / S)-phenoxy-2-propanamine or their hydrochlorides, or chiral amino acid small molecules (L / D)-tryptophan, (L / D)-lysine, (L / D)-cyclohexylglycine, (L / D)-phenylglycine, (L / D)-serine or their hydrochlorides.

[0010] Preferably, the chiral small molecule is (R / S)-1-(4-bromophenyl)ethylamine.

[0011] This invention provides a method for preparing a chiral P(VDF-TrFE-CFE)-based quaternary block ferroelectric polymer material as described above, the specific steps of which are as follows:

[0012] Step 1: Add P(VDF-TrFE-CFE) powder to organic solvent A and stir at room temperature until fully dissolved to obtain a transparent solution B;

[0013] Step 2: Add chiral small molecules to solution B and stir the reaction at room temperature under a nitrogen atmosphere to obtain solution C containing the product;

[0014] Step 3: Slowly pour solution C into mixed solvent D, filter, and obtain yellow product E;

[0015] Wherein, solvent D is a mixed solvent of ethanol and deionized water in a volume ratio of 1:1 to 1:5;

[0016] Step 4: Dissolve the yellow product E in organic solvent A to obtain a yellow solution. Pour the obtained yellow solution back into mixed solvent D, filter, and collect the solid.

[0017] Step 5: Place the solid collected in Step 4 into a vacuum oven and dry it thoroughly to obtain a chiral ferroelectric polymer.

[0018] The organic solvent A is one of N,N-dimethylformamide (DMF), tetrahydrofuran, acetonitrile, acetone, dimethyl sulfoxide (DMSO), and 2-butanone.

[0019] The organic solvent A is selected as DMF.

[0020] In step one, the concentration of the transparent solution B is 20 mg / mL to 50 mg / mL.

[0021] The mass of the chiral small molecule added in step two is up to three times the mass of P(VDF-TrFE-CFE), and the reaction time is 1-10 days.

[0022] In step two, the mass of the chiral small molecule added is 1.5 times the mass of P(VDF-TrFE-CFE), and the reaction time is 5 days.

[0023] In step three, the volume of solvent D is 10-20 times that of solution C.

[0024] In step three, solvent D is a mixture of ethanol and deionized water with a volume ratio of 1:2.

[0025] In step four, the volume of organic solvent A is 1-2 times the volume of organic solvent A in step one.

[0026] In step four, the volume of mixed solvent D is 10-20 times the volume of organic solvent A in step four.

[0027] After repeating step four 2-5 times, the collected solids are ultrasonically cleaned 2-5 times with deionized water and ethanol, respectively.

[0028] The solid collected in step four is a filter cake.

[0029] The solid collected in step five is vacuum dried at a temperature not exceeding 60°C for a time of not less than 18 hours.

[0030] The solid collected in step five is dried at a vacuum temperature of 40°C for 24 hours.

[0031] The present invention discloses the following technical effects:

[0032] 1. This invention involves mixing chiral small molecules with the ferroelectric polymer P(VDF-TrFE-CFE) and synthesizing them in a one-step solution at room temperature. The chiral ferroelectric polymer is prepared through a simple chemical reaction, making the method simple and rapid. 2. The chiral small molecules interact with P(VDF-TrFE-CFE) to generate new block units, which serve as sites to induce chirality in the polymer. 3. This invention combines chirality and ferroelectricity. For the first time, a chiral PVDF-based polymer is obtained by introducing a chiral component into the ferroelectric polymer block. This material is the first PVDF-based polymer possessing both ferroelectricity and chirality. This not only increases the possibility of ferroelectric polymers crystallizing in polar point groups but also broadens the potential applications of ferroelectric polymers in optics. 4. This invention allows for the preparation of chiral ferroelectric polymer films using either a casting or spin-coating method. (iv) Description of the attached drawings:

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the design of the present invention. M is the corresponding chiral small molecule, and x, y, z, and k are the molar contents of VDF, TrFE, CFE, and ME block connecting the chiral small molecule M in the polymer, respectively. Among them, x, y, and z are 62%, 31.5%, and 6.5%, respectively, and the value of k is related to the reaction time and the molar ratio and type of chiral small molecules. k is less than 5%.

[0035] Figure 2 The chiral quaternary block ferroelectric polymer of Example 1 of this invention and pure P(VDF-TrFE-CFE) 1 H NMR comparison spectrum;

[0036] Figure 3 The XRD phase purity comparison spectra of the chiral quaternary block ferroelectric polymer and pure P(VDF-TrFE-CFE) in Example 1 of the present invention are shown.

[0037] Figure 4 The FTIR-ATR comparison spectra of the chiral quaternary block ferroelectric polymer of Example 1 of the present invention and pure P(VDF-TrFE-CFE) are shown.

[0038] Figure 5 This is a comparison chart of the DSC curves of the chiral quaternary block ferroelectric polymer and pure P(VDF-TrFE-CFE) in Example 1 of the present invention.

[0039] Figure 6 The CD spectrum of the chiral quaternary block ferroelectric polymer of Example 1 of the present invention is shown below.

[0040] Figure 7 This is a PE curve of the chiral quaternary block ferroelectric polymer of Example 1 of the present invention. (V) Specific Implementation Methods:

[0041] The chiral quaternary block ferroelectric polymer of this invention is obtained by chemically reacting chiral small molecules with P(VDF-TrFE-CFE), exhibiting chirality corresponding to the chiral small molecules. The synthesis of this invention is short and the preparation conditions are simple, requiring only one step at room temperature.

[0042] Example 1:

[0043] Preparation of chiral quaternary block ferroelectric polymer P(VDF-TrFE-CFE-ME):

[0044] Weigh 0.5 g of P(VDF-TrFE-CFE) powder into a round-bottom flask, add 15 mL of N,N-dimethylformamide (DMF), and stir at room temperature until completely dissolved; add 0.8 g of (R)-1-(4-bromophenyl)ethylamine, and stir at room temperature under a nitrogen atmosphere for 5 days; slowly pour the reaction solution into 200 mL of a 1:2 mixture of ethanol and deionized water, filter, and obtain an orange-yellow crude product; dissolve the crude product again in 15 mL of DMF, and then pour it into 200 mL of a 1:2 mixture of ethanol and deionized water, repeating twice; ultrasonically wash the obtained product three times with deionized water to fully remove the solvent, and then ultrasonically wash it three times with ethanol to remove water and any possible residual amine; place the obtained orange-yellow product in a vacuum oven and dry at 40 °C for 24 h to obtain the orange-yellow chiral ferroelectric polymer P(VDF-TrFE-CFE-RME).

[0045] Similarly, using (S)-1-(4-bromophenyl)ethylamine as a reactant, the chiral ferroelectric polymer P(VDF-TrFE-CFE-SME) was prepared.

[0046] Using nuclear magnetic resonance hydrogen spectroscopy (NMR) 1 The polymer was characterized by 1H NMR to determine the content of ME blocks. Deuterated acetonitrile was used as the solvent, and the results are as follows: Figure 2 As shown, the peaks with chemical shifts of 7.6–7.2 ppm correspond to hydrogen atoms on the benzene ring of (R / S)-1-(4-bromophenyl)ethylamine; the peaks of 6.8–5.8 ppm correspond to hydrogen atoms on the ME block backbone; and the peaks of 5.7–4.8 ppm correspond to hydrogen atoms on the trifluoroethylene unit (TrFE). Since the content of TrFE, y, is known, it can be calculated that…

[0047] The content (k) of chiral small molecules in P(VDF-TrFE-CFE-RME) is 1.16%, and the content (k) of chiral small molecules in P(VDF-TrFE-CFE-SME) is 1.36%.

[0048] The phase purity of the chiral ferroelectric polymer was characterized using X-ray diffraction (XRD) and compared with that of pure P(VDF-TrFE-CFE). The results are as follows: Figure 3 As shown, the diffraction peak at 2θ of 19.5° corresponds to the ferroelectric phase (β phase). The β phase content of the ferroelectric polymer hardly changed after the introduction of chiral small molecules, indicating that the introduction of chiral small molecules has almost no effect on the formation of the β phase.

[0049] The phase purity and characteristic functional groups of chiral ferroelectric polymers were characterized using attenuated total reflectance Fourier transform infrared spectroscopy (FTIR-ATR). The results were compared with those of pure P (VDF-TrFE-CFE). Figure 4 As shown, compared to pure P(VDF-TrFE-CFE), the infrared spectra of P(VDF-TrFE-CFE-RME) and P(VDF-TrFE-CFE-SME) contain C=N double bonds, C=C double bonds, and benzene rings, proving the successful synthesis of the quaternary block polymer. Furthermore, their β-phase and α-phase contents are almost identical, further demonstrating that the introduction of chiral small molecules has virtually no impact on the formation of the β-phase.

[0050] The phase transition temperature and crystallinity of chiral polymers were characterized using differential scanning calorimetry (DSC), and the results are as follows: Figure 5 As shown, compared to pure P(VDF-TrFE-CFE), the melting peaks of P(VDF-TrFE-CFE-RME) and P(VDF-TrFE-CFE-SME) gradually shift towards lower temperatures, and the areas enclosed by the peaks are basically equal. This indicates that the melting point of the polymer decreases after the introduction of the ME block, but the crystallinity remains almost unchanged. Furthermore, P(VDF-TrFE-CFE) exhibits a weak Curie transition at 35°C, while the polymer with the chiral amine block exhibits a strong Curie transition around 50°C. This suggests that the introduction of the new block weakens the barrier to the Curie transition.

[0051] The chirality of the polymer was characterized using a circular dichroism spectroscopy (CD) instrument. A DMF solution of the polymer was drop-coated onto a quartz glass substrate, and the test was performed after the solvent had completely evaporated. The results are as follows: Figure 6As shown, the CD spectra of P(VDF-TrFE-CFE-RME) and P(VDF-TrFE-CFE-SME) exhibit strong CD signal intensities, with absorption peaks at similar heights but opposite directions, showing a good mirror correspondence. This indicates that the chirality of the chiral small molecule was successfully introduced into the polymer, inducing the polymer to form the corresponding chirality.

[0052] The ferroelectric properties of the polymer were characterized using a ferroelectric testing instrument. Figure 7 for

[0053] Electric field-polarization (PE) curves of P(VDF-TrFE-CFE-SME) at 1 kHz. As shown in the figure, the remanent polarization of the chiral polymer increases with increasing electric field, reaching 0.05 μC / cm at an electric field of 10 MV / m. 2 Under an electric field of 50 MV / m, the remanent polarization is 0.2 μC / cm. 2 This indicates that the chiral polymer has good ferroelectric properties.

[0054] Example 2:

[0055] Preparation of chiral quaternary block ferroelectric polymer P(VDF-TrFE-CFE-ME):

[0056] Weigh 0.5 g of P(VDF-TrFE-CFE) powder into a round-bottom flask, add 20 mL of tetrahydrofuran (THF), and stir at room temperature until completely dissolved; add 0.5 g of (S)-N-benzyl-1-phenylethylamine, and stir at room temperature under a nitrogen atmosphere for 7 days; slowly pour the reaction solution into a 1:5 volume ratio of ethanol and deionized water mixture, filter, and obtain a light yellow crude product; dissolve the crude product again in 25 mL of THF, and then pour it into 300 mL of a 1:5 volume ratio of ethanol and deionized water mixture, repeating twice; ultrasonically wash the obtained product four times with deionized water and ethanol respectively to fully remove the solvent and any possible residual amine; place the obtained orange-yellow product in a vacuum oven and dry at 40 °C for 24 h to obtain a light yellow chiral ferroelectric polymer with a ME block content (k value) of 1.94%.

[0057] Example 3:

[0058] Preparation of chiral quaternary block ferroelectric polymer P(VDF-TrFE-CFE-ME):

[0059] Weigh 0.5 g of P(VDF-TrFE-CFE) powder into a round-bottom flask, add 10 mL of acetonitrile, and stir at room temperature until completely dissolved; add 0.6 g of (R)-2-amino-1-phenylethanol, and stir at room temperature under a nitrogen atmosphere for 8 days; slowly pour the reaction solution into 150 mL of a 1:3 volume ratio of ethanol and deionized water mixture, filter, and obtain a yellow crude product; dissolve the crude product again in 20 mL of acetonitrile, and then pour it into 300 mL of a 1:3 volume ratio of ethanol and deionized water mixture, repeating this process three times; ultrasonically wash the obtained product three times with deionized water and ethanol respectively to fully remove the solvent and any possible residual amines; place the obtained yellow product in a vacuum oven and dry at 45 °C for 18 h to obtain a yellow chiral ferroelectric polymer with a ME block content (k value) of 2.12%.

[0060] Example 4:

[0061] Preparation of chiral quaternary block ferroelectric polymer P(VDF-TrFE-CFE-ME):

[0062] Weigh 0.5 g of P(VDF-TrFE-CFE) powder into a round-bottom flask, add 25 mL of acetone, and stir at room temperature until completely dissolved; add 1.5 g of (L)-lysine hydrochloride, and stir at room temperature under a nitrogen atmosphere for 3 days; slowly pour the reaction solution into a 1:1 volume ratio of ethanol and deionized water mixture, filter, and obtain a light yellow crude product; dissolve the crude product again in 30 mL of acetone, and then pour it into 400 mL of a 1:1 volume ratio of ethanol and deionized water mixture, repeating this process four times; ultrasonically wash the obtained product twice with deionized water and ethanol respectively to fully remove the solvent and any possible residual amino acids; place the obtained orange-yellow product in a vacuum oven and dry at 60 °C for 36 h to obtain a light yellow chiral ferroelectric polymer with a ME block content (k value) of 0.97%.

[0063] Example 5:

[0064] Preparation of chiral quaternary block ferroelectric polymer P(VDF-TrFE-CFE-ME):

[0065] Weigh 0.5 g of P(VDF-TrFE-CFE) powder into a round-bottom flask, add 18 mL of DMSO, and stir at room temperature until completely dissolved; add 0.4 g of (L)-tryptophan, and stir at room temperature for 1 day under a nitrogen atmosphere; slowly pour the reaction solution into 250 mL of a 1:3.5 volume ratio mixture of ethanol and deionized water, filter, and obtain a light pink crude product; dissolve the crude product again in 25 mL of DMSO, and then pour it into 250 mL of a 1:3.5 volume ratio mixture of ethanol and deionized water, repeating this process five times; ultrasonically wash the obtained product twice with deionized water and ethanol to thoroughly remove the solvent and any possible residual amino acids; place the obtained product in a vacuum oven and dry at 50 °C for 24 h to obtain a light pink chiral ferroelectric polymer with a ME block content (k value) of 0.11%.

[0066] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A chiral P(VDF-TrFE-CFE)-based quaternary block ferroelectric polymer material, characterized in that... It is formed by the chemical reaction of chiral small molecules with P(VDF-TrFE-CFE) to form new ME blocks, and exhibits chirality corresponding to the chiral small molecules.

2. The chiral P(VDF-TrFE-CFE)-based quaternary block ferroelectric polymer material according to claim 1, characterized in that... The molar content of ME blocks in the chiral ferroelectric polymer increases with increasing reaction time, but does not exceed 5%; the color of the chiral ferroelectric polymer deepens with increasing molar content of ME blocks, gradually changing from light yellow to dark yellow.

3. The chiral P(VDF-TrFE-CFE)-based quaternary block ferroelectric polymer material according to claim 1, characterized in that... The chiral small molecules include, but are not limited to, chiral amine small molecules (R / S)-2-amino-1-phenylethanol, (R / S)-1-(4-bromophenyl)ethylamine, (R / S)-N-benzyl-1-phenylethylamine, (R / S)-α-methylbenzylamine, (R / S)-phenoxy-2-propanamine or their hydrochlorides, or chiral amino acid small molecules (L / D)-tryptophan, (L / D)-lysine, (L / D)-cyclohexylglycine, (L / D)-phenylglycine, (L / D)-serine or their hydrochlorides.

4. A method for preparing a chiral P(VDF-TrFE-CFE)-based quaternary block ferroelectric polymer material, characterized in that... The specific steps are as follows: Step 1: Add P(VDF-TrFE-CFE) powder to organic solvent A and stir at room temperature until fully dissolved to obtain a transparent solution B; Step 2: Add chiral small molecules to solution B and stir the reaction at room temperature under a nitrogen atmosphere to obtain solution C containing the product; Step 3: Slowly pour solution C into mixed solvent D, filter, and obtain yellow product E; Wherein, solvent D is a mixed solvent of ethanol and deionized water in a volume ratio of 1:1 to 1:5; Step 4: Dissolve the yellow product E in organic solvent A to obtain a yellow solution. Pour the obtained yellow solution back into mixed solvent D, filter, and collect the solid. Step 5: Place the solid collected in Step 4 into a vacuum oven and dry it thoroughly to obtain a chiral ferroelectric polymer.

5. The method for preparing a chiral P(VDF-TrFE-CFE)-based quaternary block ferroelectric polymer material according to claim 4, characterized in that... The organic solvent A is one of N,N-dimethylformamide (DMF), tetrahydrofuran, acetonitrile, acetone, dimethyl sulfoxide (DMSO), and 2-butanone.

6. The method for preparing a chiral P(VDF-TrFE-CFE)-based quaternary block ferroelectric polymer material according to claim 4, characterized in that... In step one, the concentration of the transparent solution B is 20 mg / mL to 50 mg / mL.

7. The method for preparing a chiral P(VDF-TrFE-CFE)-based quaternary block ferroelectric polymer material according to claim 4, characterized in that... The mass of the chiral small molecule added in step two is up to three times the mass of P(VDF-TrFE-CFE), and the reaction time is 1-10 days.

8. The method for preparing a chiral P(VDF-TrFE-CFE)-based quaternary block ferroelectric polymer material according to claim 4, characterized in that... In step three, the volume of solvent D is 10-20 times that of solution C.

9. The method for preparing a chiral P(VDF-TrFE-CFE)-based quaternary block ferroelectric polymer material according to claim 4, characterized in that... The volume of organic solvent A in step four is 1-2 times the volume of organic solvent A in step one; The volume of mixed solvent D in step four is 10-20 times the volume of organic solvent A in step four; After repeating step four 2-5 times, the collected solids are ultrasonically cleaned 2-5 times with deionized water and ethanol, respectively.

10. The method for preparing a chiral P(VDF-TrFE-CFE)-based quaternary block ferroelectric polymer material according to claim 4, characterized in that... The solid collected in step five is vacuum dried at a temperature not exceeding 60°C for a time of not less than 18 hours.

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