Carbonized polymer / cellulose nanocrystal composite material for efficient circular polarization luminescence and phosphorescence emission as well as preparation and application of carbonized polymer / cellulose nanocrystal composite material

Abstract

The invention provides a carbonized polymer / cellulose nanocrystal composite material with high-efficiency circularly polarized light emission and phosphorescence emission as well as preparation and application of the carbonized polymer / cellulose nanocrystal composite material. The preparation method of the composite material comprises the following steps: fully dispersing polyethylene glycol, rhodamine B and a hydrochloric acid aqueous solution in water, carrying out hydrothermal reaction, filtering, dialyzing, concentrating and freeze-drying to obtain a red light carbonized polymer; and fully dispersing the red light carbonized polymer in a cellulose nanocrystal aqueous solution, and drying to obtain the carbonized polymer / cellulose nanocrystal composite material with high-efficiency circular polarization luminescence and phosphorescence emission. The preparation method is simple, and raw materials are cheap, easy to obtain, green and environment-friendly; the obtained composite material is a composite film, the mechanical strength is greatly improved, efficient red circular polarization luminescence is shown, and an extremely high asymmetry factor value is achieved; meanwhile, the composite film realizes room-temperature phosphorescence emission, the fluorescence lifetime is greatly prolonged, and obvious long afterglow emission is observed under the room-temperature condition.

Description

Technical Field

[0001] The invention belongs to the technical field of fluorescent and phosphorescent materials, and specifically relates to a carbonized polymer / cellulose nanocrystal composite material with high-efficiency circularly polarized luminescence and phosphorescent emission, and the preparation and application thereof. Background Art

[0002] Circularly polarized luminescence (CPL) has irreplaceable advantages in 3D imaging, information encryption, biological probes, etc. due to its asymmetric luminescence characteristics. Generally speaking, there are two main ways to produce CPL materials: using building blocks with chirality and fluorescence emission functions and co-assembly of non-chiral fluorescence emitters and chiral materials. Among various chiral luminescent molecular systems, inorganic lanthanide complexes can easily obtain higher asymmetry factor values, and the highest asymmetry factor value reported comes from Eu(III) complexes. Compared with inorganic complexes, organic systems can adjust their emission by adjusting the excited state electron level, but they are difficult to apply in practice due to the low asymmetry factor value.

[0003] Carbonized polymer is a new type of nanocarbon material prepared from the bottom up. It not only has adjustable optical properties, but also inherits the properties of polymers. Its highly cross-linked network structure also makes it possible to achieve room temperature phosphorescence. Therefore, it has broad application prospects as a functional light-emitting unit. However, research on carbonized polymers in chiral luminescence has not made a major breakthrough. Because chiral precursors are easily destroyed under high temperature conditions, it is difficult to prepare high-performance chiral circularly polarized luminescent carbonized polymers. At present, one development idea is to select a suitable chiral template to induce non-chiral carbonized polymer dots to produce circularly polarized luminescence.

[0004] Composite materials using cellulose nanocrystals as chiral templates are feasible in inducing circularly polarized luminescence from non-chiral luminescent sources. Cellulose nanocrystals are a type of natural material with a chiral structure that can produce a chiral liquid crystal phase under concentration induction. However, currently, the circularly polarized luminescence generated by nanocarbon materials is almost always blue, and reports of long-wavelength emission such as red circularly polarized luminescence are extremely rare. At the same time, research on phosphorescence emission based on cellulose nanocrystals is also relatively lacking.

[0005] Chinese patent document CN 110540666 A discloses a crystalline nanocellulose-based dual circularly polarized light / fluorescent film material, a preparation method and its application in anti-counterfeiting labels. The present invention adopts a one-step method to capture the metastable crystalline nanocellulose nematic phase in situ by changing the two self-assembly conditions of the evaporation temperature and the initial concentration of the crystalline nanocellulose colloidal solution, and obtains a fully crystalline nanocellulose film with a left-handed chiral nematic structure embedded in the nematic phase defect. This nematic phase defect structure has a half-wavelength blocking effect, which causes the chirality of circularly polarized light to flip to obtain selective reflection of left-handed and right-handed dual circularly polarized light; and by embedding fluorescent objects, a dual circularly polarized fluorescence signal regulated by an optical bandgap is obtained in the near-ultraviolet to near-infrared band. However, the film material of the invention has the problems of poor toughness and easy breakage, and the luminescence is limited to fluorescence emission. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission and its preparation and application. The preparation method of the present invention is simple, the raw materials are cheap and readily available, and it is green and environmentally friendly; the composite material obtained by the present invention is a composite film, the mechanical strength is greatly improved, and it exhibits high efficiency red circularly polarized luminescence and has an extremely high asymmetry factor value (g lum ); at the same time, the composite film achieved room temperature phosphorescence emission, the fluorescence lifetime was greatly increased and obvious long afterglow emission was observed under room temperature conditions.

[0007] In order to achieve the above object, the present invention adopts the following technical scheme:

[0008] A method for preparing a carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission, comprising the steps of:

[0009] (1) polyethylene glycol (PEG), rhodamine B, and hydrochloric acid aqueous solution are fully dispersed in water, subjected to hydrothermal reaction, and then filtered, dialyzed, concentrated, and freeze-dried to obtain a red light carbonized polymer;

[0010] (2) The red light carbonized polymer is fully dispersed in the cellulose nanocrystal aqueous solution and dried to obtain a carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission.

[0011] Preferably according to the present invention, in step (1), the mass average molecular weight of the polyethylene glycol is 1000 to 200000, preferably 5000 to 20000.

[0012] Preferably according to the present invention, in step (1), the mass concentration of the hydrochloric acid aqueous solution is 30%-37%.

[0013] Preferably, in step (1), the mass ratio of polyethylene glycol to rhodamine B is 8-12:1; the mass ratio of polyethylene glycol to aqueous hydrochloric acid solution is 8-15 g / mL; and the mass ratio of polyethylene glycol (PEG) to water is 1:60-70.

[0014] Preferably, according to the present invention, in step (1), polyethylene glycol is first dissolved in water, then an aqueous hydrochloric acid solution is added, and finally rhodamine B is added, and mechanical stirring is performed to mix and disperse the mixture evenly.

[0015] Preferably according to the present invention, in step (1), the hydrothermal reaction temperature is 200°C to 250°C, preferably 220°C to 230°C, and the hydrothermal reaction time is 1 to 5 hours, preferably 2 to 3 hours.

[0016] According to the preferred embodiment of the present invention, in step (1), the molecular weight cut-off of the dialysis bag used for dialysis is 1000-30000Da, preferably 10000-15000Da. The filtrate after filtration is placed in the dialysis bag, and deionized water is placed outside the dialysis bag.

[0017] According to the preferred embodiment of the present invention, in step (1), the dialysis time is 5 to 12 days, preferably 7 to 10 days. After the dialysis is completed, the solution in the dialysis bag is concentrated and freeze-dried to obtain the red light carbonized polymer powder.

[0018] Preferably according to the present invention, in step (2), the concentration of the cellulose nanocrystal aqueous solution is 10 to 50 mg / mL, preferably 30 to 40 mg / mL.

[0019] Preferably, according to the present invention, in step (2), the method for preparing the cellulose nanocrystal aqueous solution comprises the steps of: mixing paper scraps with a 60-70wt% sulfuric acid aqueous solution, stirring for reaction, then adding water to stop the acid hydrolysis reaction, standing, centrifuging to obtain the supernatant, and dialyzing, diluting or concentrating the supernatant to obtain the cellulose nanocrystal aqueous solution.

[0020] Preferably, the mass ratio of paper scraps to aqueous sulfuric acid is 1:5-15 g / mL; the stirring reaction temperature is 45-55° C., the stirring reaction time is 20-40 minutes; and the standing time is 10-20 hours.

[0021] Preferably, according to the present invention, in step (2), the mass ratio of the red light carbonized polymer to the cellulose nanocrystals is 1:3.3-100.

[0022] Preferably, according to the present invention, in step (2), the mixed solution of the red light carbonized polymer and the cellulose nanocrystal aqueous solution is transferred to a culture dish and dried at 20-30°C to obtain a carbonized polymer / cellulose nanocrystal composite material with high-efficiency circularly polarized luminescence and phosphorescence emission; the drying time is 2 to 5 days, preferably 3 to 4 days.

[0023] A carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission is prepared by the above method.

[0024] Preferably according to the present invention, the carbonized polymer / cellulose nanocrystal composite material is a composite film of red light carbonized polymer and cellulose nanocrystals.

[0025] Application of the carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission in red circularly polarized luminescence and / or long afterglow phosphorescence emission devices.

[0026] The technical features and beneficial effects of the present invention are as follows:

[0027] 1. The method for preparing the carbonized polymer using PEG and rhodamine B as raw materials is simple, and the raw materials are environmentally friendly, cheap and easily available. The product red light carbonized polymer inherits the structure of the high molecular polymer PEG, has good solubility in water, and can produce orange-red fluorescence under 365nm ultraviolet light irradiation, but the fluorescence lifetime is short.

[0028] 2. The carbonized polymer of the present invention is prepared based on the dehydration condensation between the hydroxyl group at the end of polyethylene glycol and the carboxyl group of rhodamine B and the polymerization carbonization process of the two; hydrochloric acid, as a small molecular acid, catalyzes the formation of the carbonized polymer, because although rhodamine B contains a carboxyl group, it is not easy to react with a hydroxyl group, an amino group, etc., and the addition of hydrochloric acid promotes the grafting of the carbon point surface and the polymer; if no hydrochloric acid aqueous solution is added, the solid-state luminescence intensity of the obtained carbonized polymer will be greatly reduced. In addition, the present invention uses ultra-large molecular weight PEG, and rhodamine B has obvious aggregation quenching behavior as a dye. The long molecular chain of large molecular weight PEG can effectively disperse the fluorescent chromophore, resist the aggregation-induced quenching effect, and realize the efficient solid-state luminescence of carbon points.

[0029] 3. In the composite film of the present invention, the red light carbonized polymer and the cellulose nanocrystals are evenly dispersed due to the electrostatic interaction force. The composite film of the present invention presents a bright structural color. The addition of the red light carbonized polymer significantly improves the mechanical strength of the cellulose nanocrystal film, giving the film the toughness to bend without breaking. The composite film of the present invention realizes room temperature phosphorescence emission, the phosphorescence emission peak position is about 570 nanometers, and its fluorescence lifetime increases from 3.35 nanoseconds of the red light carbonized polymer to 27.14 milliseconds, and an obvious phosphorescence long afterglow phenomenon is observed.

[0030] 4. The principle of the method of the present invention is based on the chiral liquid crystal phase formed by the concentration drive of cellulose nanocrystals. After the film is dried, the internal chiral structure will be retained. With the help of the chiral structure inside the film, the non-chiral red light carbonized polymer is induced to produce efficient red circularly polarized luminescence. The fluorescence emission peak is around 570 nanometers. By adjusting the preparation conditions, the circularly polarized luminescence can be regulated. The highest asymmetry factor value of the film sample is as high as 0.6.

[0031] 5. The carbonized polymer of the present invention retains the basic structure of high molecular weight PEG. The cellulose film itself has poor mechanical strength and is fragile. The long molecular chain polymer mixed with cellulose nanocrystals greatly enhances the mechanical strength of the film. At the same time, the addition of the carbonized polymer changes the interlayer spacing of the film, further affects the optical properties of the film, and changes the structural color of the film, so that the circularly polarized luminescence of the composite film can be regulated. Finally, in addition to the circularly polarized fluorescence, the long afterglow emission of phosphorescence visible to the naked eye is also achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the X-ray diffraction pattern of the red light carbonized polymer powder obtained in Example 1.

[0033] Figure 2 This is the Fourier transform infrared spectrum of the red light carbonized polymer obtained in Example 1 and the raw materials Rhodamine B and PEG.

[0034] Figure 3 This is a fluorescence emission spectrum of the red light carbonized polymer powder obtained in Example 1 at an excitation wavelength of 500nm to 560nm.

[0035] Figure 4 This is a fluorescence emission spectrum of the red light carbonized polymer aqueous solution obtained in Example 1 at an excitation wavelength of 500nm to 560nm.

[0036] Figure 5 The fluorescence emission spectra of the carbonized polymers obtained in Example 1 and Examples 6 to 10 at an excitation wavelength of 550 nm.

[0037] Figure 6 This is the UV-visible absorption spectrum of the red light carbonized polymer aqueous solution with a concentration of 0.5-5 mg / mL obtained in Example 1.

[0038] Figure 7 The following are photos of the film samples obtained in Examples 1 to 5 under natural light (top) and 365 nm ultraviolet light (bottom).

[0039] Figure 8 The ultraviolet absorption spectra of the films obtained in Comparative Example 1 and Examples 1 to 5 are shown.

[0040] Fig. 92 are the reflection spectra of the films obtained in Comparative Example 1 and Examples 1 to 5.

[0041] Fig.10 This is the fluorescence spectrum of the thin film sample obtained in Example 1.

[0042] Fig.11 This is the fluorescence spectrum of the thin film sample obtained in Example 2.

[0043] Fig.12 This is the fluorescence spectrum of the thin film sample obtained in Example 3.

[0044] Fig.13 This is the fluorescence spectrum of the thin film sample obtained in Example 4.

[0045] Fig.14 This is the fluorescence spectrum of the thin film sample obtained in Example 5.

[0046] Fig.15 This is the fluorescence lifetime of the red light carbonized polymer powder obtained in Example 1 at 570 nanometers.

[0047] Fig.16 This is the phosphorescence spectrum of the thin film sample obtained in Example 5.

[0048] Fig.17 This is the fluorescence lifetime of the thin film sample obtained in Example 5 at 570 nm.

[0049] Fig.18 This is the phosphorescence afterglow image of the film sample obtained in Example 5 after the ultraviolet lamp is removed.

[0050] Fig.19 Circularly polarized luminescence spectra of the thin film samples obtained in Examples 1 to 5.

[0051] Fig. 20 The following are photos comparing the mechanical strength of the film samples obtained in Comparative Example 1 and Example 5.

[0052] Fig.21 1 and 2 are stress-strain curves of the film samples obtained in Comparative Example 1 and Examples 1 to 5. DETAILED DESCRIPTION

[0053] In order to better understand the present invention, it is further described below in conjunction with specific embodiments.

[0054] Unless otherwise specified, the experimental methods used in the examples are conventional methods.

[0055] Unless otherwise specified, the materials and reagents used in the examples can be obtained from commercial sources.

[0056] The cellulose nanocrystals used in the embodiment are obtained by hydrolyzing cellulose with sulfuric acid. The specific steps are as follows: first, 1g of paper scraps and 10mL of 64wt% sulfuric acid aqueous solution are stirred and reacted at 50°C, and 100mL of deionized water is added after 30 minutes to stop the acid hydrolysis reaction. After standing for 12 hours, the supernatant is centrifuged and dialyzed (the molecular weight cutoff of the dialysis bag is 10000Da, and the dialysis is performed at room temperature for 7 days) to obtain a cellulose nanocrystal aqueous solution. The obtained cellulose nanocrystal aqueous solution can be diluted or concentrated as needed.

[0057] Example 1

[0058] A method for preparing a carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission, comprising the steps of:

[0059] Take 0.1544g PEG (mass average molecular weight is about 8000) in a beaker, add 10.125mL water, fully dissolve; then add 13μL hydrochloric acid aqueous solution with a mass concentration of 37%, and finally add 0.0154g rhodamine B, use mechanical stirring to mix evenly, add to the reactor, and place the reactor in an oven for hydrothermal reaction at a temperature of 230°C. Hydrothermal reaction for 2h, after the sample is naturally cooled to room temperature, filter, transfer the filtrate to a 10000Da dialysis bag, immerse the dialysis bag in deionized water, and dialyze at room temperature for 7 days. After the solution in the dialysis bag after dialysis is evaporated to remove most of the water, a concentrated solution is obtained, and the concentrated solution is freeze-dried to obtain red light carbonized polymer powder.

[0060] Weigh 1.2 mg of red light carbonized polymer powder and add it to 3 mL of 40 mg / mL (mass ratio of red light carbonized polymer to cellulose nanocrystal is 1:100) cellulose nanocrystal aqueous solution, and mix evenly by mechanical stirring. Transfer the mixed solution to a plastic petri dish with a diameter of 30 mm and dry it at 25 ° C for 3 days to obtain the final red light carbonized polymer / cellulose nanocrystal composite film.

[0061] Example 2

[0062] A method for preparing a carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission is as described in Example 1, except that: the red light carbonized polymer powder is changed to 6 mg (the mass ratio of the red light carbonized polymer to the cellulose nanocrystals is 1:20); the other steps and conditions are consistent with Example 1.

[0063] Example 3

[0064] A method for preparing a carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission is as described in Example 1, except that: the red light carbonized polymer powder is changed to 12 mg (the mass ratio of the red light carbonized polymer to the cellulose nanocrystal is 1:10); the other steps and conditions are consistent with Example 1.

[0065] Example 4

[0066] A method for preparing a carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission is as described in Example 1, except that: the red light carbonized polymer powder is changed to 24 mg (the mass ratio of the red light carbonized polymer to the cellulose nanocrystals is 1:5); the other steps and conditions are consistent with Example 1.

[0067] Example 5

[0068] A method for preparing a carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission is as described in Example 1, except that: the red light carbonized polymer powder is changed to 36 mg (the mass ratio of the red light carbonized polymer to the cellulose nanocrystals is 1:3.3); the other steps and conditions are consistent with Example 1.

[0069] Example 6

[0070] A method for preparing a carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission is as described in Example 1, except that the hydrothermal reaction temperature is changed from 230°C to 200°C; the other steps and conditions are consistent with Example 1.

[0071] Example 7

[0072] A method for preparing a carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission is as described in Example 1, except that the hydrothermal reaction temperature is changed from 230°C to 210°C; the other steps and conditions are consistent with Example 1.

[0073] Example 8

[0074] A method for preparing a carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission is as described in Example 1, except that the hydrothermal reaction temperature is changed from 230° C. to 220° C.; the other steps and conditions are consistent with Example 1.

[0075] Example 9

[0076] A method for preparing a carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission is as described in Example 1, except that the hydrothermal reaction temperature is changed from 230° C. to 240° C.; the other steps and conditions are consistent with Example 1.

[0077] Example 10

[0078] A method for preparing a carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission is as described in Example 1, except that the hydrothermal reaction temperature is changed from 230°C to 250°C; the other steps and conditions are consistent with Example 1.

[0079] Comparative Example 1

[0080] A method for preparing a cellulose nanocrystal film comprises the following steps:

[0081] 3 mL of 40 mg / mL cellulose nanocrystal aqueous solution was transferred to a plastic culture dish with a diameter of 30 mm and dried at 25° C. for 3 days to obtain a cellulose nanocrystal film.

[0082] Test Example 1

[0083] The X-ray diffraction and Fourier transform infrared spectra of the red light carbonized polymer obtained in Example 1 are as follows: Figure 1 and Figure 2 The sharp diffraction peaks in X-ray diffraction correspond to the folded crystals of polyoxyethylene ether chains. The absorption peaks of infrared spectra are analyzed and the absorption peaks of the products are basically consistent with those of PEG, indicating that the carbonized polymer maintains the basic structure of PEG.

[0084] Test Example 2

[0085] The red light carbonized polymer obtained in Example 1 emits orange-red fluorescence under ultraviolet light. The emission spectrum of the carbonized polymer powder is as follows: Figure 3 As shown, the emission peak of the powder is around 570 nanometers. The powder has good water solubility, and the emission spectrum of the aqueous solution with a concentration of 10 mg / ml is as follows Figure 4 As shown in the figure, the emission peak position is also around 570 nanometers, and the optimal excitation wavelength appears at 550 nanometers. And the emission peak position does not move substantially with the change of the excitation wavelength, indicating that there is a specific luminescence center. Figure 5 The fluorescence emission changes of carbonized polymers at different temperatures of 200-250°C were demonstrated. As the reaction temperature increased, the degree of carbonization continued to increase, and the best effect was achieved when the reaction temperature was 230°C.

[0086] Test Example 3

[0087] The red light carbonized polymer aqueous solution obtained in Example 1 (concentrations of 0.5, 1, 2, 3, 4, 5 mg mL -1 ) UV absorption spectrum Figure 6 As shown, the absorbance increases with the increase of concentration, and there is an obvious absorbance peak at 550 nm. Figure 7The following are photos of the film samples obtained in Examples 1 to 5 under natural light and 365 nm ultraviolet light. When the amount of carbonized polymer added is small, the film exhibits bright structural color and exhibits weak orange fluorescence under ultraviolet light; as the amount of carbonized polymer added increases, the film structural color weakens, and the red color given by the carbonized polymer occupies the main part, indicating that the addition of carbonized polymer gradually changes the internal structure of the film. The absorption spectra and reflection spectra of the composite films prepared in Examples 1 to 5 and Comparative Example 1 are shown in Figure 2. Figure 8 , 9 As shown in the figure, it can be seen that as the amount of carbonized polymer added increases, the composite film gradually shows an absorption peak at 550 nanometers, further proving the successful incorporation of carbonized polymer. And as the amount of addition increases, the positions of the absorption peak and reflection peak of the cellulose nanocrystal itself move toward a larger wavelength, indicating that the addition of carbonized polymer gradually increases the internal interlayer spacing of the film.

[0088] Test Example 4

[0089] The fluorescence emission spectra of the films obtained in Examples 1 to 5 are as follows: Figures 10 to 14 As shown. The fluorescence emission peak of the film sample is around 570 nanometers, and the fluorescence intensity increases with the amount of carbonized polymer added. The film obtained in Example 5 with the highest fluorescence intensity has a fluorescence quantum yield of up to 41.72%, while the fluorescence quantum yield of the carbonized polymer powder is only 6.42%. This shows that the method of encapsulating the carbonized polymer into the cellulose film can greatly improve the fluorescence ability of the carbonized polymer.

[0090] Test Example 5

[0091] The fluorescence lifetime of the carbonized polymer powder prepared in Example 1 at 570 nm is as follows: Fig.15 As shown, only 3.35 nanoseconds. The carbonized polymer was encapsulated into a film using the preparation method of the present invention (the film prepared in Example 5) to produce phosphorescence emission. The phosphorescence spectrum is shown in Fig.16 As shown, the 480-nanometer emission peak corresponds to the phosphorescence peak of cellulose nanocrystals themselves, and the 570-nanometer emission peak is the red phosphorescence emission produced by carbonized polymers. The phosphorescence lifetime is as long as 27.14 milliseconds ( Fig.17 After the UV light was removed, obvious yellow phosphorescence emission was observed, as shown in Fig.18 shown.

[0092] Test Example 6

[0093] Thanks to the internal chiral nematic structure, the cellulose-based composite film can selectively reflect natural light of a specific wavelength and convert it into right-handed circularly polarized light. The films obtained in Examples 1 to 5 induce the non-chiral carbonized polymer to produce strong circularly polarized luminescence. The circularly polarized spectrum under 500 nm excitation conditions is as follows: Fig.19The internal structure of the composite film maintains a chiral nematic structure. The addition of the carbonized polymer affects the interlayer spacing of the chiral structure, thereby achieving the regulation of its optical properties. The asymmetry factor value of the film sample increases first and then decreases with the addition of the carbonized polymer. The maximum asymmetry factor value appears in the film sample of Example 2, which is as high as 0.6.

[0094] Test Example 7

[0095] The film formed by cellulose nanocrystals has extremely low mechanical strength and is easily broken, while the film sample obtained by this method has greatly improved mechanical strength and can be bent multiple times without breaking. Fig. 20 The following pictures show a film made of pure cellulose (Comparative Example 1) and a composite film with carbonized polymer added (Example 5). The cellulose film cracks during the preparation process due to its poor mechanical strength. However, the addition of long molecular chain carbonized polymer makes the composite film softer and increases the energy dissipation of the composite film during movement. Therefore, the composite film exhibits higher mechanical strength and toughness and can be bent repeatedly. The stress-strain curves of the films obtained in Examples 1 to 5 and Comparative Example 1 are shown in Figure 2. Fig.21 shown.

Claims

1. A method for preparing a carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission, comprising the steps of: (1) Polyethylene glycol (PEG), rhodamine B, and hydrochloric acid aqueous solution are fully dispersed in water, subjected to hydrothermal reaction, and then filtered, dialyzed, concentrated, and freeze-dried to obtain a red light carbonized polymer; (2) The red light carbonized polymer is fully dispersed in the cellulose nanocrystal aqueous solution and dried to obtain a carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission.

2. The method for preparing the carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission according to claim 1, characterized in that: In step (1), one or more of the following conditions are included: i. The mass average molecular weight of the polyethylene glycol is 1000 to 200000, preferably 5000 to 20000; ii. The mass concentration of the hydrochloric acid aqueous solution is 30%-37%; iii. The mass ratio of polyethylene glycol to rhodamine B is 8-12:1; the mass ratio of polyethylene glycol to the volume ratio of hydrochloric acid aqueous solution is 8-15 g / mL; the mass ratio of polyethylene glycol (PEG) to water is 1:60-70; iv. The molecular weight cut-off of the dialysis bag used for dialysis is 1000-30000Da, preferably 10000-15000Da; v. The dialysis time is 5 to 12 days, preferably 7 to 10 days.

3. The method for preparing the carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission according to claim 1, characterized in that: In step (1), the hydrothermal reaction temperature is 200°C to 250°C, preferably 220°C to 230°C, and the hydrothermal reaction time is 1 to 5 hours, preferably 2 to 3 hours.

4. The method for preparing the carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission according to claim 1, characterized in that: In step (2), the concentration of the cellulose nanocrystal aqueous solution is 10 to 50 mg / mL, preferably 30 to 40 mg / mL.

5. The method for preparing the carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission according to claim 1, characterized in that: In step (2), the method for preparing the cellulose nanocrystal aqueous solution comprises the steps of: mixing paper scraps with a 60-70 wt % sulfuric acid aqueous solution, stirring the mixture for reaction, then adding water to stop the acid hydrolysis reaction, standing the mixture, centrifuging the mixture to obtain a supernatant, and dialyzing, diluting or concentrating the supernatant to obtain a cellulose nanocrystal aqueous solution; Preferably, the mass ratio of paper scraps to aqueous sulfuric acid is 1:5-15 g / mL; the stirring reaction temperature is 45-55° C., the stirring reaction time is 20-40 minutes; and the standing time is 10-20 hours.

6. The method for preparing the carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission according to claim 1, characterized in that: In step (2), the mass ratio of the red light carbonized polymer to the cellulose nanocrystals is 1:3.3-100.

7. The method for preparing the carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission according to claim 1, characterized in that: In step (2), the mixed solution of the red light carbonized polymer and the cellulose nanocrystal aqueous solution is transferred to a culture dish and dried at 20-30°C to obtain a carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission; the drying time is 2 to 5 days, preferably 3 to 4 days.

8. A carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission, prepared by the method according to any one of claims 1 to 7.

9. The carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission according to claim 8, characterized in that: The carbonized polymer / cellulose nanocrystal composite material is a composite film of red light carbonized polymer and cellulose nanocrystal.

10. Use of the carbonized polymer / cellulose nanocrystal composite material with high efficiency circularly polarized luminescence and phosphorescence emission as claimed in any one of claims 1 to 7 in red circularly polarized luminescence and / or long afterglow phosphorescence emission devices.

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