Block copolymer nanoparticle having liquid crystal properties, method for preparing same, and use thereof

Abstract

The present invention discloses a block copolymer nanoparticle having liquid crystal properties, a method for preparing same, and use thereof. The structural formula of the block copolymer nanoparticle is represented by formula (1). In the present invention, by using the characteristic kinetic traps in the polymerization-induced self-assembly method, liquid crystal block copolymer nanoparticles with a high solid content and a uniform size are obtained. The present invention can not only obtain traditional worm-like liquid crystal block copolymer micelles, but also obtain spherical liquid crystal block copolymer micelles with an adjustable degree of birefringence. The present invention not only improves the processability of the liquid crystal block copolymer nanoparticles, but also significantly improves the possibility of large-scale manufacturing thereof by increasing the solid content, possessing remarkable application prospects in polymer materials and biopharmaceutics.

Description

Block copolymer nanoparticles with liquid crystal properties, their preparation method and applications Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a block copolymer nanoparticle with liquid crystal properties, its preparation method, and its application. Background Technology

[0002] Liquid crystal polymer nanoparticles, with their unique molecular orientation, high mechanical strength, tunable optical properties, responsiveness, self-healing ability, and self-assembly characteristics, have broad application prospects in materials science, optical devices, sensors, and biomedicine. However, liquid crystal polymer nanoparticles are generally prepared using "post-polymerization" self-assembly methods, including solution exchange, centrifugation-induced self-assembly, and microfluidic technology. These methods typically require low-concentration (less than 1% w / w) dilute solutions, severely limiting the large-scale preparation of polymeric vesicles. Furthermore, the wide size distribution of the prepared liquid crystal polymer nanoparticles also affects their applications. Therefore, liquid crystal polymer nanoparticles are often used at lower solution concentrations, such as in drug delivery, where they can effectively load and protect drugs and promote drug absorption. For example, Chinese patent CN 106389336 B describes liquid crystal nanoparticles that combine the properties of lyotropic liquid crystals with the drug-loading efficacy of nanoparticles, exhibiting solubilization, encapsulation, and protection of drugs, as well as promoting drug absorption, and are also biodegradable. Although strategies such as seed crystal growth and in-situ nucleation-growth have been developed for the preparation of optical materials in liquid crystal polymer nanoparticles, it is still difficult to improve the solid content concentration and precise size control.

[0003] To achieve high-solids-content liquid crystal polymer nanoparticles in solution, polymerization-induced self-assembly (PISA) is widely considered a universal technique for preparing block copolymer nanoparticles. The polymer structures prepared by PISA are generally block copolymers, i.e., solvent-friendly homopolymer precursors undergo subsequent polymer chain growth via methods such as reversible addition-fragmentation chain transfer polymerization (RAFT). During polymerization, the block copolymers undergo solution self-assembly due to phase separation, forming liquid crystal polymer nanoparticles with different morphologies. Using the PISA method, the solid content of the polymer nanoparticle solution is typically 5-20% w / w, or even as high as 50% w / w, while the polymer nanoparticle size is highly uniform. However, PISA is prone to inducing a kinetic trap effect, which restricts the morphological transformation of block copolymer self-assembled nanoparticles from spherical micelles to higher-order structures (such as worm-like micelles and vesicles). Few studies have translated this kinetic trap into an advantage in polymer nanoparticle preparation to control the morphology of polymer nanoparticles. Summary of the Invention

[0004] To address the shortcomings and deficiencies of existing technologies, the primary objective of this invention is to provide block copolymer nanoparticles with liquid crystal properties.

[0005] Another objective of this invention is to provide a method for preparing block copolymer nanoparticles with liquid crystal properties. This method uses simple materials, is easy to prepare, has reasonable cost, and can be mass-produced.

[0006] Another object of the present invention is to provide applications of the above-mentioned block copolymer nanoparticles with liquid crystal properties.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] The block copolymer nanoparticles with liquid crystal properties proposed in this invention have the following general formula for their block copolymer structure:

[0009] In formula (1), m = 20 to 100, n = 20 to 500, x = 0 to 600; R is a liquid crystal side group.

[0010] In this invention, R is a liquid crystal side group, selected from the following structures:

[0011] (abbreviated as 0CB) (abbreviated as 2CB) and (Abbreviated as 6CB).

[0012] In this invention, when the R group has the structural formula 0CB, the block copolymer structure is formed by covalently linking N,N-dimethylaminoethyl methacrylate (PDMA) and poly(4-(2-methacryloyloxy)-4′-cyanobiphenyl) (PMA0CB). When the R group has the structural formula 2CB, the block copolymer structure is formed by covalently linking N,N-dimethylaminoethyl methacrylate (PDMA) and poly(2-(4-cyanobiphenyl-4′-yloxy)ethyl methacrylate) (PMA2CB). When the R group has the structural formula 6CB, the block copolymer structure is formed by covalently linking N,N-dimethylaminoethyl methacrylate (PDMA), poly(6-((4-cyano-4′-biphenyl)oxy)hexyl methacrylate) (PMA6CB), and polybenzyl methacrylate (PBzMA).

[0013] In the general formula (1), when R is 0CB or 2CB, x is 0; when R is 6CB, x = 1 to 600.

[0014] This invention proposes a method for preparing block copolymer nanoparticles with liquid crystal properties, comprising the following steps:

[0015] S1. The precursor and triethylamine were mixed in tetrahydrofuran and placed in an ice bath reaction vessel. The tetrahydrofuran solution of methacryloyl chloride was slowly added to the mixture and stirred in an ice bath. After the reaction was completed, most of the solvent was evaporated under vacuum. The remaining mixture was then poured into water, filtered to separate the precipitate, and dried under vacuum. The precipitate was then purified by column chromatography using chloroform as the eluent to prepare monomer M.

[0016] S2. N,N-dimethylaminoethyl methacrylate (DMA), chain transfer agent, azobisisobutyronitrile (AIBN) and tetrahydrofuran are placed in a reactor; after a "freeze-thaw-evacuation" cycle, the reactor is sealed and heated to 65-75°C for reaction; the reaction product is purified using petroleum ether to obtain PDMA macromolecular chain transfer agent;

[0017] S3. The monomer M, PDMA macromolecular chain transfer agent and oil-soluble initiator are dissolved in a polar solvent and sealed in a reactor. Under inert gas conditions, the mixture is heated at 60-80°C to obtain nanoparticles N assembled from the block copolymer PDMA-PM block copolymer.

[0018] S4. Benzyl methacrylate (BzMA) and an oil-soluble initiator are dissolved in a polar solution of block copolymer nanoparticles N; under inert gas conditions, the reaction is carried out at 60–80 °C to obtain nanoparticles Q assembled from the block copolymer PDMA-PM-PBzMA.

[0019] Preferably, when the R group in the general formula (1) has the structural formula OCB, the precursor is cyanobiphenol (abbreviated as A0CB), with the structural formula as follows:

[0020] When the R group in the general formula (1) has a structural formula of 2CB or 6CB, the precursor is prepared by the following steps: potassium carbonate, cyanobiphenyl compound, potassium iodide and acetone are placed in a reaction vessel and stirred vigorously at reflux temperature. Then, a bromine-substituted compound solution diluted with acetone is added dropwise to the reaction vessel. Subsequently, the reaction solution is refluxed for 10 to 12 hours. After the reaction is completed, the mixture is precipitated with water and washed with water, and then dried under vacuum to prepare the precursor.

[0021] More preferably, when the R group has the structural formula 2CB, the cyanobiphenyl compound and the brominated compound are 4-hydroxy-4′-cyanobiphenyl and bromoethanol, respectively; when the R group has the structural formula 6CB, the cyanobiphenyl compound and the brominated compound are 4-hydroxy-4′-cyanobiphenyl and 6-bromo-1-hexanol, respectively.

[0022] More preferably, the molar ratio of potassium carbonate, cyanobiphenyl compound, potassium iodide, and bromine-substituted compound is 15 mmol:5 mmol:4 mmol:6 mmol. Acetone is used as a solvent, and its volume is not strictly limited.

[0023] More preferably, the reflux temperature of the acetone is 70°C.

[0024] More preferably, the acetone-diluted bromine-substituted compound solution is added dropwise to the reaction vessel at a rate of one drop every two seconds.

[0025] More preferably, the vacuum drying temperature is 40-50°C and the time is 12-24 hours.

[0026] When the R group in general formula (1) has the structural formula 2CB, the precursor is prepared by using 4-hydroxy-4′-cyanobiphenyl and correspondingly using bromoethanol, and is 4-hydroxyethoxy-4′-cyanobiphenyl (A2CB), with the structural formula [not specified].

[0027] When the corresponding R group has the structural formula 6CB, the precursor is prepared by using 4-hydroxy-4′-cyanobiphenyl and correspondingly 6-bromo-1-hexanol, resulting in 4-hydroxyhexyloxy-4′-cyanobiphenyl (A6CB), with the structural formula [not provided in the original text].

[0028] In step S1, when the monomer M corresponds to the structural formula OCB for the R group, it is prepared using the precursor A0CB, which is 4-(2-methacryloyloxy)-4′-cyanobiphenyl (MA0CB), with the structural formula [not specified].

[0029] When the monomer M corresponds to the R group with the structural formula 2CB, it is prepared using the precursor A2CB, and is 2-(4-cyanobiphenyl-4′-yloxy)ethyl methacrylate (MA2CB), with the structural formula [not specified].

[0030] When the monomer M corresponds to the structural formula 6CB for the R group, it is prepared using the precursor A6CB, and is 6-((4-cyano-4′-biphenyl)oxy)hexyl methacrylate (MA6CB), with the structural formula [not specified].

[0031] Preferably, in step S1, the molar ratio of the precursor, triethylamine, and methacrylamide chloride is 4 mmol:5 mmol:4 mmol. Tetrahydrofuran is used as the solvent, and its volume does not need to be strictly limited.

[0032] Preferably, in step S1, the stirring time in the ice bath is 12 to 24 hours.

[0033] Preferably, in step S1, the vacuum drying temperature is 30–40°C and the time is 20–24 hours.

[0034] Preferably, in step S2, the molar ratio of DMA, chain transfer agent, and AIBN is 100–500 mmol: 5 mmol: 1 mmol to obtain a PDMA macromolecular chain transfer agent with 20–100 DMA repeating units. Tetrahydrofuran is used as the solvent, and its volume does not need to be strictly limited.

[0035] Preferably, in step S2, the chain transfer agent includes, but is not limited to, at least one of the following chain transfer agents: 2-cyano-2-propylbenzodisulfide, phenyl dithioester, phenyl trithiocarbonate, or cyanomethyl methyl (phenyl)amino dithiocarbamate.

[0036] Preferably, in step S2, the heating reaction time is 8 to 12 hours.

[0037] The block copolymer PDMA-PM described in step S3 is obtained by using the monomer MA0CB to obtain poly(N,N-dimethylaminoethyl methacrylate)-poly(4-(2-methacryloyloxy)-4′-cyanobiphenyl) (PDMA-PMA0CB), with the following structural formula:

[0038] In the formula, m = 20 to 100, n = 20 to 500;

[0039] The block copolymer PDMA-PM was obtained using the monomer MA2CB to obtain poly(N,N-dimethylaminoethyl methacrylate)-poly(2-(4-cyanobiphenyl-4′-yloxy)ethyl methacrylate) (PDMA-PMA2CB), with the following structural formula:

[0040] In the formula, m = 20 to 100, n = 20 to 500;

[0041] The block copolymer PDMA-PM was obtained using the monomer MA6CB to obtain poly(N,N-dimethylaminoethyl methacrylate)-poly(6-((4-cyano-4′-biphenyl)oxy)hexyl methacrylate) (PDMA-PMA6CB), with the structural formula:

[0042] In the formula, m = 20 to 100, and n = 20 to 500.

[0043] Preferably, in step S3, the molar ratio of monomer M, PDMA macromolecular chain transfer agent, and AIBN is 100–2500 mmol: 5 mmol: 1 mmol to obtain a PDMA-PM block copolymer with 20–500 repeating units M. The polar solvent is used as the solvent, and its volume does not need to be strictly limited.

[0044] In step S3, the polar solvent includes, but is not limited to, at least one of the polar solvents such as ethanol, propanol, butanol, pentanol, and water.

[0045] Preferably, in step S3, the oil-soluble initiator includes, but is not limited to, at least one of the following oil-soluble initiators: azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, and dimethyl azobisisobutyrate.

[0046] Preferably, in step S3, the reaction temperature is 70°C.

[0047] Preferably, in step S3, the heating reaction time is 8 to 24 hours.

[0048] In step S3, the nanoparticles N formed by the block copolymer assembly include, but are not limited to, at least one of the following nanoparticle morphologies: spherical micelles, worm-like micelles, sheet-like micelles, or vesicles.

[0049] In step S4, the PDMA-PM in the block copolymer nanoparticles N is specified as PDMA-PMA6CB.

[0050] Preferably, in step S4, the molar ratio of PDMA-PM polymer in BzMA, AIBN, and block copolymer nanoparticles N is 5–3000 mmol:1 mmol:5 mmol to obtain a PDMA-PM-PBzMA block copolymer with 1–600 repeating BzMA units. The structural formula of the PDMA-PM-PBzMA block copolymer is as follows:

[0051] In the formula, m = 20 to 100, n = 20 to 500, and x = 1 to 600.

[0052] In step S4, the polar solvent includes, but is not limited to, at least one of the polar solvents such as ethanol, propanol, butanol, pentanol, and water.

[0053] Preferably, in step S4, the oil-soluble initiator includes, but is not limited to, at least one of the following oil-soluble initiators: azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, and dimethyl azobisisobutyrate.

[0054] Preferably, in step S4, the reaction temperature is 70°C.

[0055] Preferably, in step S4, the heating reaction time is 12 to 24 hours.

[0056] In step S4, the nanoparticles Q formed by the block copolymer assembly include, but are not limited to, at least one of the following nanoparticle morphologies: spherical micelles, worm-like micelles, sheet-like micelles, or vesicles.

[0057] The block copolymer nanoparticles with liquid crystal properties described in this invention can be applied to novel polymer optical materials and the biomedical field.

[0058] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0059] (1) The present invention prepares a block copolymer solution with high solid content (5-20% w / w) by PISA method, and the block copolymer nanoparticles prepared are uniform in size.

[0060] (2) This invention not only relates to obtaining block copolymer self-assembled worm-like micelles with traditional liquid crystal properties (such as birefringence), but more importantly, it utilizes the kinetic trap brought by PISA to obtain isotropic spherical micelles with birefringence properties that are easy to process later.

[0061] (3) By introducing non-liquid crystal block copolymers as nanoparticle core materials, the liquid crystal properties of the original liquid crystal block copolymer nanoparticles can be adjusted by changing the degree of polymerization of the non-liquid crystal blocks. Attached Figure Description

[0062] Figure 1 shows the 1H NMR spectrum of the PDMA macromolecular chain transfer agent prepared from S3. The characteristic peaks marked on the structural formula indicate that the PDMA macromolecular chain transfer agent was successfully synthesized.

[0063] Figure 2 shows the 1H NMR spectrum of the monomer M, MA0CB, prepared in Example 1.

[0064] Figure 3 shows the 1H NMR spectrum of the block copolymer PDMA-PM prepared in Example 1, namely PDMA-PMA0CB.

[0065] Figure 4 shows a transmission electron microscope image of the block copolymer PDMA-PM prepared in Example 1, which is PDMA-PMA0CB self-assembled nanoparticles. It can be seen that a typical long worm-like micelle structure is formed.

[0066] Figure 5 shows a polarization optical microscope image of the block copolymer PDMA-PM prepared in Example 1 as PDMA-PMA0CBd self-assembled nanoparticles. The bright texture pattern can be seen in the image, indicating that the prepared nanoparticles have liquid crystal behavior.

[0067] Figure 6 shows the 1H NMR spectrum of the monomer M, MA2CB, prepared in Example 2.

[0068] Figure 7 shows the 1H NMR spectrum of the block copolymer PDMA-PM prepared in Example 2, which is PDMA-PMA2CB.

[0069] Figure 8 shows a transmission electron microscope image of the block copolymer PDMA-PM prepared in Example 2, which is PDMA-PMA2CB self-assembled nanoparticles. It can be seen that short worm-like micelle structures are formed.

[0070] Figure 9 shows a polarization optical microscope image of the block copolymer PDMA-PM2CB self-assembled nanoparticles prepared in Example 2. The bright texture pattern can be seen in the image, indicating that the prepared nanoparticles have liquid crystal behavior.

[0071] Figure 10 shows the 1H NMR spectrum of the monomer M, MA6CB, prepared in Example 3.

[0072] Figure 11 shows the 1H NMR spectrum of the block copolymer PDMA-PM prepared in Example 3, which is PDMA-PMA6CB.

[0073] Figure 12 is a transmission electron microscope image of the block copolymer PDMA-PM prepared in Example 3, which is PDMA-PMA6CB self-assembled nanoparticles. It can be seen that a typical spherical micelle structure is formed, which is small and uniform in size.

[0074] Figure 13 is a polarization optical microscope image of the block copolymer PDMA-PM, specifically PDMA-PMA6CB self-assembled nanoparticles prepared in Example 3. The image shows a bright, typical liquid crystal molecule texture pattern, indicating that the prepared nanoparticles exhibit liquid crystal behavior.

[0075] Figure 14 shows the 1H NMR spectrum of the block copolymer PDMA-PM-PBzMA prepared in Example 4, which is PDMA-PMA6CB-PBzMA.

[0076] Figure 15 shows a transmission electron microscope image of the block copolymer PDMA-PM-PBzMA prepared in Example 4, which is a self-assembled nanoparticle of PDMA-PMA6CB-PBzMA. It can be seen that a typical spherical micelle structure is formed, with significantly increased and uniform size.

[0077] Figure 16 shows a polarization optical microscope image of the self-assembled nanoparticles of the block copolymer PDMA-PM-PBzMA prepared in Example 4, namely PDMA-PMA6CB-PBzMA. The image shows that the texture pattern is weakened, indicating that the liquid crystal properties of the prepared nanoparticles are controlled. Detailed Implementation

[0078] The present invention will be further described in detail below with reference to embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto. All raw materials involved in the present invention can be purchased directly from the market. For process parameters not specifically specified, conventional techniques can be referred to.

[0079] Example 1

[0080] S1. Acquisition of A0CB precursor: A0CB can be purchased directly from the market without special preparation.

[0081] S2. Synthesis of MA0CB monomer: A0CB (12.00 g) and triethylamine (7.77 g) were mixed in 300 mL of tetrahydrofuran and placed in an ice-bath reaction vessel. A tetrahydrofuran solution of methacryloyl chloride (6.40 g) was added dropwise every two seconds to the above mixture, and the mixture was stirred in an ice-bath for 18 hours. After the reaction was completed, most of the solvent was evaporated under vacuum, and the remaining mixture was poured into water, filtered to separate the precipitate, and dried under vacuum at 30 °C for 20 hours. The precipitate was then purified by column chromatography using chloroform as the eluent to prepare the MA0CB monomer (structural characterization is shown in Figure 2).

[0082] S3.PDMA 25 Synthesis of macromolecular chain transfer agent: DMA (5.0 g), 2-cyano-2-propylbenzodisulfide (0.28 g), AIBN (0.04 g), and 100 mL of tetrahydrofuran were placed in a reactor. After a "freeze-thaw-evacuation" cycle, the reactor was sealed and heated in an oil bath at 70 °C for 8 hours. The reaction product was purified using petroleum ether to obtain PDMA macromolecular chain transfer agent with a degree of polymerization of 25. 25 .

[0083] S4. Obtain PDMA using the PISA method 25 -PMA0CB 50 Liquid crystal block copolymer nanoparticles: These nanoparticles contain monomers MA0CB (0.80 g) and PDMA. 25 A macromolecular chain transfer agent (0.24 g) and AIBN (2.00 mg) were dissolved in 20 mL of ethanol to obtain a mixture with a solid content of 5%, which was then sealed in a reactor. Under inert gas conditions, the reactor was heated in an oil bath at 70 °C for 8 hours to obtain PDMA with PMA0CB segments having a degree of polymerization of 50. 25 -PMA0CB 50 The nanoparticles assembled from block copolymers (the structural characterization is shown in Figure 3, the morphology of the nanoparticles is shown in Figure 4, and the polarized light microscope image is shown in Figure 5).

[0084] Example 2

[0085] S1. A2CB precursor preparation: Potassium carbonate (21.23 g), 4-hydroxy-4′-cyanobiphenyl (10.00 g), potassium iodide (6.81 g), and 200 mL of acetone were placed in a reaction vessel and vigorously stirred at 70 °C. Then, 50 mL of bromoethanol (7.69 g) diluted in acetone was added dropwise to the reaction vessel every two seconds. Subsequently, the reaction solution was refluxed at 70 °C for 20 hours. After the reaction was completed, the mixture was precipitated with water, washed three times with water, and dried in a vacuum oven to obtain the precursor A2CB.

[0086] S2. Synthesis of MA2CB monomer: A2CB (12.20 g) and triethylamine (6.44 g) were mixed in 300 mL of tetrahydrofuran and placed in an ice-bath reaction vessel. A tetrahydrofuran solution of methacryloyl chloride (5.31 g) was added dropwise every two seconds to the above mixture, and the mixture was stirred in an ice-bath for 18 hours. After the reaction was completed, most of the solvent was evaporated under vacuum, and the remaining mixture was poured into water, filtered to separate the precipitate, and dried under vacuum at 30 °C for 24 hours. The precipitate was then purified by column chromatography using chloroform as the eluent to prepare the MA2CB monomer (structural characterization is shown in Figure 6).

[0087] S3.PDMA 40 Synthesis of macromolecular chain transfer agent: DMA (7.0 g), 2-cyano-2-propylbenzodisulfide (0.25 g), AIBN (0.04 g), and 100 mL of tetrahydrofuran were placed in a reactor. After a "freeze-thaw-evacuation" cycle, the reactor was sealed and heated in an oil bath at 70 °C for 10 hours. The reaction product was purified using petroleum ether to obtain PDMA macromolecular chain transfer agent with a degree of polymerization of 40. 40 .

[0088] S4. Obtain PDMA using the PISA method 40 -PMA2CB 50 Liquid crystal block copolymer nanoparticles: These nanoparticles contain monomers MA2CB (0.80 g) and PDMA. 40 A macromolecular chain transfer agent (0.33 g) and AIBN (1.71 mg) were dissolved in 9 mL of propanol to obtain a mixture with a solid content of 10%, which was then sealed in a reactor. Under inert gas conditions, the reactor was heated in an oil bath at 70 °C for 12 hours to obtain PDMA with PMA2CB segments having a degree of polymerization of 50. 40 -PMA2CB 50 Nanoparticles assembled from block copolymers (structural characterization is shown in Figure 7, nanoparticle morphology is shown in Figure 8, and polarized light microscope image is shown in Figure 9).

[0089] Example 3

[0090] S1. A6CB precursor preparation: Potassium carbonate (19.11 g), 4-hydroxy-4′-cyanobiphenyl (9.00 g), potassium iodide (6.13 g), and 180 mL of acetone were placed in a reaction vessel and vigorously stirred at 70 °C. Then, 50 mL of acetone-diluted 6-bromo-1-hexanol (10.02 g) solution was added dropwise to the reaction vessel at a rate of one drop every two seconds. Subsequently, the reaction solution was refluxed at 70 °C for 20 hours. After the reaction was completed, the mixture was precipitated with water and washed three times with water, then dried in a vacuum oven to obtain the precursor A6CB.

[0091] S2. Synthesis of MA6CB monomer: A6CB (10.50 g) and triethylamine (4.49 g) were mixed in 250 mL of tetrahydrofuran and placed in an ice-bath reaction vessel. A tetrahydrofuran solution of methacryloyl chloride (3.70 g) was added dropwise every two seconds to the above mixture, and the mixture was stirred in an ice-bath for 20 hours. After the reaction was completed, most of the solvent was evaporated under vacuum, and the remaining mixture was poured into water, filtered to separate the precipitate, and dried under vacuum at 40 °C for 24 hours. The precipitate was then purified by column chromatography using chloroform as the eluent to prepare the MA6CB monomer (structural characterization is shown in Figure 10).

[0092] S3.PDMA 55 Synthesis of macromolecular chain transfer agent: DMA (7.3 g), 2-cyano-2-propylbenzodisulfide (0.19 g), AIBN (0.03 g), and 100 mL of tetrahydrofuran were placed in a reactor. After a "freeze-thaw-evacuation" cycle, the reactor was sealed and heated in an oil bath at 70 °C for 12 hours. The reaction product was purified using petroleum ether to obtain PDMA macromolecular chain transfer agent with a degree of polymerization of 55. 55 .

[0093] S4. Obtain PDMA using the PISA method 55 -PMA6CB 50 Liquid crystal block copolymer nanoparticles: These nanoparticles contain monomers MA6CB (0.75g) and PDMA. 55 A macromolecular chain transfer agent (0.36 g) and AIBN (1.36 mg) were dissolved in 5.2 mL of propanol / water (90 / 10 w / w) to obtain a mixture with a solid content of 15%, which was then sealed in a reactor. Under inert gas conditions, the reactor was heated in an oil bath at 70 °C for 18 hours to obtain PDMA with PMA6CB segments having a degree of polymerization of 50. 55 -PMA6CB 50 Nanoparticles assembled from block copolymers (structural characterization is shown in Figure 11, nanoparticle morphology is shown in Figure 12, and polarized light microscope image is shown in Figure 13).

[0094] Example 4

[0095] S1. A6CB precursor preparation: Potassium carbonate (21.23 g), 4-hydroxy-4′-cyanobiphenyl (10.00 g), potassium iodide (6.81 g), and 200 mL of acetone were placed in a reaction vessel and vigorously stirred at 70 °C. Then, 50 mL of acetone-diluted 6-bromo-1-hexanol (11.14 g) solution was added dropwise to the reaction vessel at a rate of one drop every two seconds. Subsequently, the reaction solution was refluxed at 70 °C for 24 hours. After the reaction was completed, the mixture was precipitated with water, washed three times with water, and dried in a vacuum oven to obtain the precursor A6CB.

[0096] S2. Synthesis of MA6CB monomer: A6CB (12.50 g) and triethylamine (5.35 g) were mixed in 300 mL of tetrahydrofuran and placed in an ice-bath reaction vessel. A tetrahydrofuran solution of methacryloyl chloride (4.41 g) was added dropwise every two seconds to the above mixture, and the mixture was stirred in an ice-bath for 20 hours. After the reaction was completed, most of the solvent was evaporated under vacuum, and the remaining mixture was poured into water, filtered to separate the precipitate, and dried under vacuum at 40 °C for 24 hours. The precipitate was then purified by column chromatography using chloroform as the eluent to prepare the MA6CB monomer.

[0097] S3.PDMA 55 Synthesis of macromolecular chain transfer agent: DMA (7.7 g), 2-cyano-2-propylbenzodisulfide (0.20 g), AIBN (0.03 g), and 200 mL of tetrahydrofuran were placed in a reactor. After a "freeze-thaw-evacuation" cycle, the reactor was sealed and heated in an oil bath at 70 °C for 12 hours. The reaction product was purified using petroleum ether to obtain PDMA macromolecular chain transfer agent with a degree of polymerization of 55. 55 .

[0098] S4. Obtain PDMA using the PISA method 55 -PMA6CB 100 Liquid crystal block copolymer nanoparticles: These nanoparticles contain monomers MA6CB (1.60 g) and PDMA. 55 A macromolecular chain transfer agent (0.38 g) and AIBN (1.45 mg) were dissolved in 23 mL of propanol to obtain a mixture with a solid content of 8%, which was then sealed in a reactor. Under inert gas conditions, the reactor was heated in an oil bath at 70 °C for 20 hours to obtain PDMA with PMA6CB segments having a degree of polymerization of 100. 55 -PMA6CB 100 Nanoparticles formed by the assembly of block copolymers.

[0099] S5. Obtain PDMA using the RAFT method 55 -PMA6CB100 -BzMA 50 Liquid crystal block copolymer nanoparticles: BzMA (0.39 g) and AIBN (1.45 mg) were dissolved in PDMA obtained in S4. 55 -PMA6CB 100 A polar solution of block copolymer nanoparticles was prepared, resulting in a mixture with a solid content of 9.8%, which was then sealed in a reactor. Under inert gas conditions, the reactor was heated in an oil bath at 70°C for 12 hours to obtain PDMA with PBzMA segments having a degree of polymerization of 50. 55 -PMA6CB 100 -PBzMA 50 Nanoparticles assembled from block copolymers (structural characterization is shown in Figure 14, nanoparticle morphology is shown in Figure 15, and polarized light microscope image is shown in Figure 16).

[0100] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A block copolymer nanoparticle with liquid crystal properties, characterized in that... Its block copolymer structure has the following general formula: In formula (1), m = 20 to 100, n = 20 to 500, and x = 0 to 600; R is selected from the following structure:

2. The block copolymer nanoparticles with liquid crystal properties according to claim 1, characterized in that, In the structural formula (1), R is When x is 0; R is When x = 1 to 600.

3. The method for preparing block copolymer nanoparticles with liquid crystal properties as described in claim 1 or 2, characterized in that, Includes the following steps: S1. The precursor and triethylamine were mixed in tetrahydrofuran and placed in an ice bath reaction vessel. A tetrahydrofuran solution of methacryloyl chloride was added, and the mixture was stirred in an ice bath to prepare monomer M. S2. N,N-dimethylaminoethyl methacrylate, chain transfer agent, azobisisobutyronitrile and tetrahydrofuran are placed in a reactor; after a "freeze-thaw-evacuate" cycle, the reactor is sealed and heated at 65-75°C to obtain the PDMA macromolecular chain transfer agent. S3. The monomer M, PDMA macromolecular chain transfer agent and oil-soluble initiator are dissolved in a polar solvent and sealed in a reactor. Under inert gas conditions, the mixture is heated at 60-80°C to obtain nanoparticles N assembled from the block copolymer PDMA-PM block copolymer. S4. Benzyl methacrylate and an oil-soluble initiator are dissolved in a polar solution of block copolymer nanoparticles N; under inert gas conditions, the reaction is carried out at 60–80 °C to obtain nanoparticles Q assembled from block copolymers PDMA-PM-PBzMA.

4. The preparation method according to claim 3, characterized in that, When the structural formula of the corresponding R group in the general formula (1) is When the precursor is cyanobiphenol, the structural formula is: When the structural formula of the corresponding R group in the general formula (1) is The precursor is prepared by the following steps: potassium carbonate, cyanobiphenyl compound, potassium iodide and acetone are placed in a reaction vessel and stirred vigorously at reflux temperature. Then, a bromine-substituted compound solution diluted with acetone is added dropwise to the reaction vessel. Subsequently, the reaction solution is refluxed for 10 to 12 hours to prepare the precursor.

5. The preparation method according to claim 4, characterized in that, The structural formula of the R group is: In this case, the cyanobiphenyl compound and the brominated compound are 4-hydroxy-4′-cyanobiphenyl and bromoethanol, respectively; The structural formula of the R group is: In this case, the cyanobiphenyl compound and the brominated compound are 4-hydroxy-4′-cyanobiphenyl and 6-bromo-1-hexanol, respectively; The molar ratio of potassium carbonate, cyanobiphenyl compound, potassium iodide and bromine-substituted compound is 15 mmol: 5 mmol: 4 mmol: 6 mmol.

6. The preparation method according to claim 3, characterized in that, In step S1, the molar ratio of the precursor, triethylamine, and methacrylamide chloride is 4 mmol:5 mmol:4 mmol.

7. The preparation method according to claim 3, characterized in that, In step S2, the molar ratio of N,N-dimethylaminoethyl methacrylate, chain transfer agent and azobisisobutyronitrile is 100-500 mmol: 5 mmol: 1 mmol; In step S2, the chain transfer agent includes at least one of 2-cyano-2-propylbenzodisulfide, phenyl dithioester, phenyl trithiocarbonate, or cyanomethyl methyl (phenyl)amino dithiocarbamate. In step S2, the heating reaction takes 8 to 12 hours.

8. The preparation method according to claim 3, characterized in that, In step S3, the molar ratio of monomer M, PDMA macromolecular chain transfer agent and azobisisobutyronitrile is 100-2500 mmol: 5 mmol: 1 mmol; In step S3, the polar solvent includes at least one of ethanol, propanol, butanol, pentanol, and water; In step S3, the oil-soluble initiator includes at least one of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, and dimethyl azobisisobutyrate; In step S3, the heating reaction takes 8 to 24 hours; In step S3, the nanoparticles N formed by the block copolymer assembly include at least one of spherical micelles, worm-like micelles, sheet-like micelles, or vesicles.

9. The preparation method according to claim 3, characterized in that, In step S4, the PDMA-PM in the block copolymer nanoparticles N is specified as PDMA-PMA6CB; the molar ratio of benzyl methacrylate, azobisisobutyronitrile and PDMA-PM polymer in the block copolymer nanoparticles N is 5-3000 mmol: 1 mmol: 5 mmol; In step S4, the polar solvent includes at least one of ethanol, propanol, butanol, pentanol, and water; In step S4, the oil-soluble initiator includes at least one of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, and dimethyl azobisisobutyrate; In step S4, the heating reaction takes 12 to 24 hours; In step S4, the nanoparticles Q formed by the block copolymer assembly include at least one of spherical micelles, worm-like micelles, sheet-like micelles, or vesicles.

10. The application of the block copolymer nanoparticles with liquid crystal properties as described in claim 1 or 2 in the fields of novel polymer optical materials and biomedicine.

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