A kind of preparation circularly polarized optical film using gold nanorod and polyurethane vitrimer (PUV) and preparation method
By combining gold nanorods with polyurethane-based vitrimers, a three-step phase transfer method was used to prepare circularly polarized optical thin films. This solved the problem of nanorod dispersion in polymers, achieved high circular dichroism and temperature controllability, expanded the application of chiral carriers, and has broad optical and biomedical applications.
Patent Information
- Application Number
- CN202111039340.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-09-06
- Publication Date
- 2026-02-10
- Estimated Expiration
- 2041-09-06
AI Technical Summary
Existing technologies make it difficult to uniformly and stably disperse gold nanorods in polymers to prepare circularly polarized optical films with high circular dichroism. Furthermore, polymers typically lack chirality and have no absorption peaks in the ultraviolet-visible range, making it difficult to analyze chirality using CD spectroscopy.
Gold nanorods were uniformly and stably dispersed in a polyurethane-based Vitrimer (PUV) solution through a three-step phase transfer process, and circularly polarized optical films were prepared by combining gold nanorods with PUV. The specific steps included centrifugal dispersion, mixing of polymer solutions, heating and curing, and hot pressing.
The effective combination of gold nanorods and PUVs was achieved, and a circularly polarized optical thin film with high circular dichroism was prepared. The circular dichroism can be controlled by temperature, simplifying the device structure and expanding the application fields of chiral carriers. It has broad potential for optical devices, sensors and biomedical applications.
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Figure CN115755263B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer inorganic nanocomposite material preparation, and in particular to the preparation of optical materials using metal nanoparticles and polymer materials. Background Technology
[0002] Chirality is closely related to evolution in nature. From the orbits of galaxies thousands of light-years in diameter to amino acid molecules composed of only a few atoms, chirality is present in every aspect of life. Chiral materials have important applications in the field of circularly polarized optics. They exhibit different absorption characteristics for left-handed and right-handed circularly polarized light, which is usually represented by circular dichroism (CD). Utilizing this absorption difference, when natural light passes through a chiral material, it can selectively allow one type of circularly polarized light to pass through, thus converting natural light into circularly polarized light. Therefore, the stronger the CD, the stronger this selectivity.
[0003] Compared with traditional chiral organic molecules, plasma chiral materials have higher CD signal intensity, and their CD spectra can be changed by adjusting variables such as their size and structure. Therefore, they have great application potential in the fabrication of sensors, chiral catalysis, enantiomeric separation, nonlinear optics, metamaterials, and circularly polarized devices.
[0004] Chiral support methods are commonly used to prepare plasmonic chiral materials. The basic strategy involves supporting nanomaterials on a chiral support, which guides the nanoparticles to align chirally. This method is simple to operate and produces plasmonic chiral materials with high asymmetry factors (g-factors). The most fundamental condition for selecting a chiral support is that the nanoparticles can be stably dispersed within it. Hydrophilic materials such as cellulose liquid crystals, DNA origami, and chiral supramolecular hydrogels meet this requirement and are often used as chiral supports. However, these materials are typically fluid and require encapsulation before use. Recently, a research group used cured cellulose liquid crystals as a support to prepare circularly polarized optical films, signifying a significant advancement in plasmonic chiral materials, extending beyond the mobile phase to the solid phase. Solid-phase plasmonic chiral materials are more convenient for practical applications, making the development of solid-phase plasmonic chiral materials and the search for more diverse curable chiral supports of great importance.
[0005] Polymers typically possess thermosetting or thermoplastic properties and exhibit excellent mechanical properties (such as high mechanical strength, good flexibility, and ductility) as well as unique optical properties (such as high light transmittance and birefringence). Vitrimer is a special type of polymer that combines the mechanical properties of polymers with thermoplasticity, thermosetting properties, shape memory, and self-healing properties, making it a very promising new type of polymer. However, polymers have not yet been used as chiral carriers to prepare plasma chiral materials. This is because polymers are generally considered to lack chirality, and polymers typically lack absorption peaks in the ultraviolet-visible range, making it difficult to analyze polymer chirality using CD spectroscopy. Secondly, nanoparticles are mostly synthesized in aqueous phases, making it difficult for them to be uniformly and stably dispersed in organic phases containing polymers. Therefore, it is difficult to combine nanoparticles with polymers for use.
[0006] For the reasons mentioned above, it is crucial to expand the curable chiral carriers and prepare circularly polarized optical thin films with high circular dichroism. Summary of the Invention
[0007] The technical problem solved by this invention is to propose a method for preparing a circularly polarized optical thin film by uniformly and stably separating gold nanorods in a polymer monomer solution through a three-step phase transfer process and combining the gold nanorods with polyurethane-based Vitrimer.
[0008] To address the aforementioned technical problems, the present invention proposes the following technical solution: a method for preparing circularly polarized optical thin films using gold nanorods and polyurethane-based vitrimer (PUV), the preparation steps of which are as follows.
[0009] Step (1): After centrifugation and purification, the gold nanorods were dispersed in a polyvinylpyrrolidone (PVP)-N,N-dimethylformamide (DMF) solution with a PVP concentration of 12 mg / ml and a solution volume to initial gold nanorod volume ratio of 0.5-1.5:1; after centrifugation again, they were dispersed in a PVP-dichloromethane (DCM) solution for later use with a PVP concentration of 6-12 mg / ml;
[0010] Step (2): Mix polyethylene glycol, glycerin, and antioxidant and heat to melt. The antioxidant is 4,4'-bis(α,α-dimethylbenzyl)diphenylamine.
[0011] Step (3): After adding tetrahydrofuran to the mixture in step (2) for dilution, hexamethylene diisocyanate and catalyst are added sequentially under stirring. The catalyst is dibutyl dilaurate. The mixture is then thoroughly mixed.
[0012] Step (4): Under stirring, add the gold nanorod solution from step (1) to the mixture from step (3) and mix thoroughly.
[0013] Step (5): Pour the mixture from step (4) into the mold, heat and solidify for 2 hours, and then place it in a vacuum oven overnight to remove excess solvent;
[0014] Step (6): The gold nanorod-PUV composite material cured in step (5) is pressed into a circularly polarized optical film with a thickness of 0.2-0.4 mm using a hot press.
[0015] Preferably, in step (1), the volume of the gold nanorods is 40 ml, the centrifugation speed is 5500 rpm, and the centrifugation time is 15 min. After centrifugation to remove the supernatant, the nanorods are dispersed in 40 ml of 100-500 μl PVP-DMF solution, with a PVP concentration of 12 mg / ml and a PVP molecular weight of 40000.
[0016] Preferably, in step (1), when the gold nanorods dispersed in the PVP-DMF solution are centrifuged again, the centrifugation speed is 4600 rpm and the centrifugation time is 15 min; after removing the supernatant, 300 μl of PVP-DCM solution is used for dispersion, and the concentration of PVP is 6 mg / ml.
[0017] Preferably, in step (1), after centrifugation and purification, the gold nanorods are dispersed in a polyvinylpyrrolidone (PVP)-N,N-dimethylformamide (DMF) solution with a PVP concentration of 12 mg / ml and a solution volume that is the same as the initial gold nanorod volume.
[0018] Preferably, in step (2), the polyethylene glycol has a molecular weight of 2000 and a mass of 750 mg; the glycerol has a mass of 25 mg; the antioxidant has a mass of 3.9 mg; the heating temperature is 80°C; and the heating time is 30 min.
[0019] Preferably, in step (3), the volume of tetrahydrofuran is 500 μl; the volume of hexamethylene diisocyanate is 135 μl; and the volume of catalyst is 90 μl.
[0020] Preferably, the heating temperature in step (5) is 60°C; the vacuum drying temperature is 100°C.
[0021] Preferably, in step (6), the temperature of the hot press is 145°C, the pressure is 0.15 MPa, and the pressing time is 3 min.
[0022] To solve the above-mentioned technical problems, another technical solution proposed by the present invention is: a circularly polarized optical thin film prepared according to any of the above methods.
[0023] A method for preparing a circularly polarized optical thin film includes the following steps:
[0024] (1) Transfer the gold nanorods from the aqueous phase to the organic phase. Take 40 ml of gold nanorods, centrifuge at 5500 rpm for 15 min, and remove the supernatant. Redisperse with 40 ml of 12 mg / ml PVP-DMF solution, centrifuge again at 5500 rpm for 15 min, and remove the supernatant. Redisperse with 300 μl of 6 mg / ml PVP-DCM solution for further use.
[0025] (2) Weigh 750 mg polyethylene glycol, 25 mg glycerol, and 3.9 mg catalyst, heat at 80 °C for 30 min, and after melting, add 500 μl tetrahydrofuran for dilution. Then, under stirring, add 135 μl hexamethylene diisocyanate and 90 μl catalyst in sequence. Finally, under stirring, add the gold nanorods from (1), pour them into a mold, cure at 60 °C for 2 hours, and then vacuum dry at 100 °C overnight.
[0026] (3) The gold nanorod-PUV composite material in (3) was pressed into a film using a hot press at a temperature of 145℃ and a pressure of 0.15MPa for 3 minutes. The final film thickness was 0.2-0.4 mm.
[0027] The beneficial effects of this invention are:
[0028] (1) This method is simple and universal, and extends the chiral carrier from cellulose to the polymer field, which broadens the field of chiral carriers.
[0029] (2) This circularly polarized optical film can easily obtain circularly polarized light, which simplifies the equipment compared with the previous method of generating circularly polarized light by combining a linear polarizer and a quarter-wave plate.
[0030] (3) The circularly polarized optical film can control its circular dichroism by temperature. The circular dichroism weakens above 45°C and recovers at room temperature. This provides a method to control the intensity of the generated circularly polarized light by changing the temperature of the film to regulate its circular dichroism.
[0031] (4) Circularly polarized optical thin films have great application value in optical devices, sensors, photocatalysis, biomedicine and other fields.
[0032] (5) Gold nanorods of different sizes can be combined with PUV to prepare circularly polarized optical thin films.
[0033] (6) Replacing PUV with other polymers will not produce a CD signal.
[0034] (7) Replacing PUV with gold nanoparticles does not produce a CD signal.
[0035] (8) In step 1, the PVP concentration is 12 mg / ml. If the concentration is lower than 12 mg / ml, the gold rods are prone to aggregate during phase transfer. If the concentration is higher than 12 mg / ml, the concentration will be too high and will affect the next step of the operation. Attached Figure Description
[0036] The present invention will be further described below with reference to the accompanying drawings.
[0037] Figure 1 This is a surface modification of gold nanorods. (a) Optical photograph demonstrating the stability of gold nanorods during phase transfer. (b) UV-Vis and NIR absorption spectra of gold nanorods dispersed in different media. Transmission electron microscopy images showing the stability of gold nanorods in (c) aqueous solution and (d) dichloromethane, respectively.
[0038] Figure 2 This is the CD spectrum of a gold nanorod-PUV circularly polarized optical thin film.
[0039] Figure 3 CD spectra of gold nanorod-PUV circularly polarized optical thin films at different temperatures.
[0040] Figure 4 This is the CD spectrum of a gold nanorod (70 nm in length)-PUV circularly polarized optical thin film.
[0041] Figure 5 This is the CD spectrum of a gold nanoparticle-PUV circularly polarized optical thin film.
[0042] Figure 6 This is the CD spectrum of a gold nanorod-polyvinyl alcohol film.
[0043] Figure 7 This is the CD spectrum of a gold nanorod-polycaprolactone film. Detailed Implementation
[0044] Example 1
[0045] (1) Synthesis of gold nanorods: First, gold nanoparticle seeds were prepared in a 20 mL reaction flask: Sodium borohydride (NaBH4, 10 mM, 0.3 mL) was added to a mixture of tetrachloroauric acid (HAuCl4, 0.125 mL, 10 mM) and hexadecyltrimethylammonium bromide (CTAB, 5 mL, 0.1 M) under stirring. Upon vigorous shaking, the solution color instantly changed from golden yellow to brown, indicating the formation of gold nanoparticle seeds. The mixture was kept under vortex for 10 minutes to ensure complete reduction of HAuCl4. The prepared seed solution was allowed to stand at room temperature for 2 hours before being used to prepare gold nanorods. 95 mL of CTAB (0.1 M), 1 mL of silver nitrate (AgNO3, 10 mM), and 5 mL of HAuCl4 (10 mM) solution were sequentially added to a 250 mL Erlenmeyer flask. Next, 0.55 mL of L-ascorbic acid (L-AA, 0.1 M) solution was added to the mixture, and the flask was gently shaken until the solution became colorless. Finally, 0.12 mL of seed solution was added to the above mixture while gently mixing. The resulting mixture was allowed to stand overnight at room temperature to obtain gold nanorods. The gold nanorods were further purified by centrifugation and stabilized in 100 mL of CTAB solution (0.1 M) for further use.
[0046] (2) Transfer the gold nanorods from the aqueous phase to the organic phase. Take 40 ml of gold nanorods, centrifuge at 5500 rpm for 15 min, and remove the supernatant. Redisperse with 40 ml of 12 mg / ml PVP-DMF solution, centrifuge again at 5500 rpm for 15 min, and remove the supernatant. Redisperse with 300 μl of 6 mg / ml PVP-DCM solution for further use.
[0047] (3) Weigh 750 mg polyethylene glycol, 25 mg glycerol, and 3.9 mg catalyst, heat at 80 °C for 30 min, and after melting, add 500 μl tetrahydrofuran for dilution. Then, under stirring, add 135 μl hexamethylene diisocyanate and 90 μl catalyst in sequence. Finally, under stirring, add the gold nanorods from (1), pour them into a mold, cure at 60 °C for 2 hours, and then vacuum dry at 100 °C overnight.
[0048] (4) The gold nanorod-PUV composite material from (3) was pressed into a film using a hot press at a temperature of 145℃ and a pressure of 0.15MPa for 3 minutes. The final film thickness was 0.2-0.4 mm. Figure 1 It can be seen that the UV-Vis spectrum of the gold nanorods in the solution after each phase transfer step did not show a significant red shift, and no aggregation was observed in the TEM image, indicating that the phase transfer of the gold nanorods was successful. Furthermore, from... Figure 2 It can be seen that the gold nanorod-PUV film has strong circular dichroism.
[0049] Example 2
[0050] The difference from Example 1 is that the gold nanorods in step (2) of Example 1 have a length of 50-100 nm. Figure 3 It can be seen that gold nanorods of this size also exhibit circular dichroism.
[0051] Comparative Example 1
[0052] The difference from Example 1 is that step (2) in Example 1 uses gold nanoparticles. Figure 4 The results show that the gold nanoparticle-PUV film does not exhibit circular dichroism. The circular dichroism of the gold nanorod-PUV film comes from the synergistic effect of the chiral crystallization of PUV itself and the anisotropy of the gold nanorods, while gold nanoparticles are isotropic, therefore the gold nanoparticle-PUV film does not exhibit circular dichroism.
[0053] Comparative Example 2
[0054] The difference compared to Example 1 is that in step (3) of Example 1, polyvinyl alcohol is used. Figure 5 The results show that the gold nanorod-polyvinyl alcohol (PUV) film does not exhibit circular dichroism. The circular dichroism of the gold nanorod-PUV film comes from the synergistic effect of the chiral crystallization of PUV itself and the anisotropy of the gold nanorods, while polyvinyl alcohol does not have chiral crystallization, therefore the gold nanorod-PUV film does not exhibit circular dichroism.
[0055] Comparative Example 3
[0056] The difference compared to Example 1 is that step (3) in Example 1 uses polycaprolactone, from... Figure 6 The results show that the gold nanorod-polycaprolactone film does not exhibit circular dichroism. The circular dichroism of the gold nanorod-PUV film comes from the synergistic effect of the chiral crystallization of PUV itself and the anisotropy of the gold nanorods, while polycaprolactone does not have chiral crystallization, therefore the gold nanorod-polyvinyl alcohol film does not exhibit circular dichroism.
[0057] The present invention is not limited to the specific technical solutions described in the above embodiments. All technical solutions formed by equivalent substitutions are within the scope of protection claimed by the present invention.
Claims
1. A method for preparing circularly polarized optical thin films using gold nanorods and polyurethane-based vitrimer (PUV), characterized in that: The preparation steps are as follows: Step (1): After centrifugation and purification, the gold nanorods were dispersed in a polyvinylpyrrolidone (PVP)-N,N-dimethylformamide (DMF) solution with a PVP concentration of 12 mg / ml and a solution volume to initial gold nanorod volume ratio of 0.5-1.5:1; after centrifugation again, they were dispersed in a PVP-dichloromethane (DCM) solution for later use with a PVP concentration of 6 mg / ml; Step (2): Mix polyethylene glycol, glycerin, and antioxidant and heat to melt. The antioxidant is 4,4'-bis(α,α-dimethylbenzyl)diphenylamine. Step (3): After diluting the mixture in step (2) with tetrahydrofuran, hexamethylene diisocyanate and catalyst are added sequentially under stirring. The catalyst is dibutyl dilaurate. The mixture is then thoroughly mixed. Step (4): Under stirring, add the gold nanorod solution from step (1) to the mixture from step (3) and mix thoroughly; Step (5): Pour the mixture from step (4) into the mold, heat and solidify for 2 hours, then place it in a vacuum oven overnight to remove excess solvent; Step (6): The gold nanorod-PUV composite material cured in step (5) is pressed into a circularly polarized optical film with a thickness of 0.2-0.4 mm using a hot press. The temperature of the hot press is 145℃, the pressure is 0.15 MPa, and the pressing time is 3 min. The gold nanorod-PUV film has strong circular dichroism.
2. The method for preparing circularly polarized optical thin films using gold nanorods and polyurethane-based vitrimer (PUV) according to claim 1, characterized in that: In step (1), the volume of the gold nanorods is 40 ml, the centrifugation speed is 5500 rpm, and the centrifugation time is 15 min. After centrifugation to remove the supernatant, the nanorods are dispersed in 40 ml of 100-500 μl PVP-DMF solution. The concentration of PVP is 12 mg / ml and the molecular weight of PVP is 40000.
3. The method for preparing circularly polarized optical thin films using gold nanorods and polyurethane-based vitrimer (PUV) according to claim 1, characterized in that: In step (1), when the gold nanorods dispersed in the PVP-DMF solution were centrifuged again, the centrifugation speed was 4600 rpm and the centrifugation time was 15 min. After removing the supernatant, 300 μl of PVP-DCM solution was used for dispersion, and the concentration of PVP was 6 mg / ml.
4. The method for preparing circularly polarized optical thin films using gold nanorods and polyurethane-based vitrimer (PUV) according to claim 1, characterized in that: In step (1), the gold nanorods were centrifuged and purified, and then dispersed in a polyvinylpyrrolidone (PVP)-N,N-dimethylformamide (DMF) solution with a PVP concentration of 12 mg / ml and a solution volume that was the same as the initial gold nanorod volume.
5. The method for preparing circularly polarized optical thin films using gold nanorods and polyurethane-based vitrimer (PUV) according to claim 1, characterized in that: In step (2), the molecular weight of polyethylene glycol is 2000 and the mass is 750 mg; the mass of glycerol is 25 mg; the mass of antioxidant is 3.9 mg; the heating temperature is 80℃ and the heating time is 30 min.
6. The method for preparing circularly polarized optical thin films using gold nanorods and polyurethane-based vitrimer (PUV) according to claim 1, characterized in that: In step (3), the volume of tetrahydrofuran is 500 μl; the volume of hexamethylene diisocyanate is 135 μl; and the volume of catalyst is 90 μl.
7. The method for preparing circularly polarized optical thin films using gold nanorods and polyurethane-based vitrimer (PUV) according to claim 1, characterized in that: The heating temperature in step (5) is 60℃; the vacuum drying temperature is 100℃.
8. Circularly polarized optical thin films prepared according to any one of claims 1-7.