Non-iridescent film with long-range disordered / short-range ordered structure and preparation method of non-iridescent film

Abstract

The invention belongs to the technical field of functional film materials, and discloses a non-iridescent film with a long-range disordered / short-range ordered structure and a preparation method of the non-iridescent film. The method comprises the following steps: 1) uniformly mixing nanocrystalline cellulose, citric acid and nanoparticles in water to obtain a CNC / citric acid / nanoparticle mixed solution; (2) drying the CNC / citric acid / nano-particle mixed solution at alternate temperatures to form a film, so as to obtain a non-iridescent film; the alternate drying temperatures are respectively 20-30 DEG C and 50-55 DEG C, the alternate drying time at each temperature is respectively 3-10 minutes, and the drying environment humidity is 40-70%. The method is simple, and the regulation and control capability of long-range / short-range microstructure arrangement of the CNC film is greatly improved. The function of CNC non-iridescent structural colors is achieved, and the CNC non-iridescent structural colors have large application potential in the field of wide-view-angle display.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of functional film materials, and in particular relates to a non-iridescent film with a long-range disordered / short-range ordered structure and a preparation method thereof. Background Art

[0002] In recent years, cellulose nanocrystals (CNCs) have become a research hotspot in the field of photonic crystal materials due to their unique self-assembly characteristics and optical properties. Traditional CNC-based photonic crystals can produce iridescence effects (angle-dependent structural colors) through their periodic spiral arrangement structure, showing potential in fields such as sensing, decoration, and anti-counterfeiting. However, the fact that the color of the iridescence effect changes with the observation angle severely limits its application in scenarios requiring color stability, such as high-end display technology, uniform coatings, and low-reflective materials. Although static color control can be achieved through chemical dyes or quantum dots, these methods often sacrifice the natural biodegradability, renewability, and durability of structural colors of CNC.

[0003] Currently, the realization of non-iridescent structural color relies primarily on disordered photonic structures or absorption-scattering coupling mechanisms. However, the highly ordered self-assembly properties of CNCs make it difficult to overcome the inherent limitations of the iridescent effect. Therefore, developing a CNC non-iridescent film with a long-range disorder / short-range order structure is a key challenge in bridging sustainable materials and optical applications. If such a material can overcome the iridescent limitations, it will not only retain the environmental advantages of CNCs but also expand into areas such as flexible electronics, low-energy display devices, and biomimetic camouflage. It will also provide a new design paradigm for the theoretical system of photonic crystals, possessing significant scientific value and industrial potential. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention provides a non-iridescent film with a long-range disorder / short-range order structure and a method for preparing the same. This invention utilizes CNC as a substrate, citric acid as a short-range structure curing agent, and spherical nanoparticles as a long-range structure modulator. This process, supplemented by alternating temperature drying and forming, significantly enhances the ability to manipulate the long-range / short-range microstructural arrangement of the CNC film, resulting in a non-iridescent film with both long-range disorder and short-range order. This long-range disorder / short-range order structure refers to an arrangement that appears disordered when viewed from a long-range perspective but orderly at the microscopic scale.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A method for preparing a non-iridescent film having a long-range disorder / short-range order structure comprises the following steps:

[0007] 1) mixing nanocrystalline cellulose, citric acid, and nanoparticles in water to obtain a CNC / citric acid / nanoparticle mixture;

[0008] 2) Drying the CNC / citric acid / nanoparticle mixture at alternating temperatures to form a film, thereby obtaining a non-iridescent film.

[0009] In step 1), the mass ratio of nanocrystalline cellulose: citric acid: nanoparticles is (12-60):1:(5-30), preferably (15-50):1:(7.5-22.5).

[0010] The specific steps of step 1) are as follows: the nanocrystalline cellulose suspension, the citric acid solution and the nanoparticle dispersion are mixed.

[0011] The concentration of the nanocrystalline cellulose suspension, ie, the cellulose nanocrystal suspension, is 6-10 wt %.

[0012] The length of nanocrystalline cellulose is 400-600 nm.

[0013] The concentration of the citric acid solution is 2-4 wt %, and the concentration of the nanoparticle dispersion is 10-15 wt %. The solvent in the citric acid solution and the nanoparticle dispersion is water.

[0014] The nanoparticles are spherical in shape, have a diameter of 50-500 nm (preferably 70-120 nm), and are made of silicon dioxide or titanium dioxide.

[0015] Alternatively, the amount of each substance in step 1) is expressed in terms of concentration and volume, and the volume ratio of the nanocrystalline cellulose suspension: citric acid solution: nanoparticle dispersion is (8-12):1:(2-4), preferably 10:1:3.

[0016] The mixing in step 1) refers to stirring first and then ultrasonic treatment; the stirring speed is 300-400 rpm, the stirring time is 3-4 hours, the ultrasonic treatment time is 5-7 minutes, and the ultrasonic frequency of the ultrasonic treatment is 20-40KHz.

[0017] In step 2), the alternating drying temperatures are 20-30° C. and 50-55° C., the alternating drying times are 3-10 min (preferably 4-6 min), and the drying environment humidity is 40-70%.

[0018] The alternating drying specifically refers to drying at 20-30° C. for 3-10 minutes, then drying at 50-55° C. for 3-10 minutes, and alternately drying in this manner until a film is formed.

[0019] The present invention provides a bio-based non-iridescent film prepared by the above preparation method.

[0020] The non-iridescent film is used as a structural color marker for wide viewing angle display.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0022] (1) The present invention uses CNC as a substrate, citric acid as a short-range structural curing agent, and nanoparticles such as silicon dioxide as a long-range structural regulator, supplemented by alternating temperature drying and forming, which greatly improves the ability to regulate the long-range / short-range microstructure arrangement of the CNC film;

[0023] (2) The method of the present invention is simple to operate and the process is controllable;

[0024] (3) The mixed raw materials selected in the present invention are widely available, environmentally friendly, and biodegradable, and are economical and practical for the preparation, utilization, and recycling of the product;

[0025] (4) The CNC film obtained by the present invention not only has bright structural colors, but also realizes the function of CNC non-iridescent structural colors, which makes it have great application potential in the field of wide viewing angle display and broadens the application range of CNC structural color films. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The transmission spectra of the sample obtained in Example 1 at angles of 90° and 45°;

[0027] Figure 2 The microscopic morphology (SEM image) of the sample obtained in Example 1;

[0028] Figure 3 The transmission spectra of the sample obtained in Comparative Example 1 at angles of 90° and 45°;

[0029] Figure 4 The transmission spectra of the sample obtained in Comparative Example 2 at angles of 90° and 45°. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to specific examples, but the embodiments of the present invention are not limited thereto. It should be noted that if there are any processes not particularly described in detail below, they can be implemented or understood by those skilled in the art with reference to the prior art. If the manufacturer of the reagents or instruments used is not indicated, they are deemed to be conventional products that can be purchased commercially.

[0031] The nanocrystalline cellulose suspension of the present invention is obtained by treating hardwood pulp with concentrated sulfuric acid. The nanocrystalline cellulose or suspension can also be purchased.

[0032] The nanocrystalline cellulose suspension is specifically obtained by the following method: a) pre-treating hardwood pulp in a weak alkaline environment, and then drying and dehydrating; mixing the pre-treated hardwood pulp with concentrated sulfuric acid, heating under stirring, adding water to terminate the reaction, mixing and standing, centrifuging, collecting the upper suspension to obtain a suspension; b) centrifuging the suspension, taking the upper suspension, and diluting to obtain a nanocrystalline cellulose suspension.

[0033] The pH of the weak alkaline environment for pretreatment of the hardwood pulp in step a) is 8.5-9.5, provided by NaOH solution and KOH solution, and the pretreatment time is 10-14 hours.

[0034] The concentration of the concentrated sulfuric acid solution in step a) is 62-66 wt %, and the mass volume ratio of the pretreated hardwood pulp to the concentrated sulfuric acid is 1 g: (1-8) mL.

[0035] The stirring speed in step a) is 1000-1200 rpm, the heating temperature is 40-55° C., and the heating time is 20-40 min.

[0036] In step a), the volume ratio of concentrated sulfuric acid to water for terminating the reaction is 1:(9-12); and the standing time is 20 to 24 hours.

[0037] The number of centrifugation in step a) is 5 to 6 times, the centrifugal speed is 10,000 to 12,000 rpm, the centrifugal time is 8 to 10 minutes, and the centrifugal temperature is 10 to 15°C.

[0038] The number of centrifugation in step b) is 3 to 4 times, the centrifugal speed is 10,000 to 11,000 rpm, the centrifugal time is 15 to 20 minutes, and the centrifugal temperature is 10 to 15°C.

[0039] Example 1

[0040] A method for preparing a non-iridescent film having a long-range disorder / short-range order structure comprises the following steps:

[0041] (1) Pre-treat the hardwood pulp in a NaOH solution with a pH of 9 for 12 h, and then dry and dehydrate it. Mix 100 g of the pre-treated hardwood pulp with 100 ml of 62 wt% concentrated sulfuric acid, and heat the mixture at a stirring rate of 1000 rpm and a temperature of 55°C for 20 min. Then, add 1000 ml of deionized water, mix well, and let it stand for 22 h to terminate the reaction.

[0042] (2) The mixed solution of step (1) was centrifuged at a speed of 12000 rpm for 9 minutes, the centrifugal temperature was controlled at 10°C, and the upper suspension after centrifugation was collected after centrifugation for 5 times to obtain a neutral suspension; the neutral suspension was centrifuged at a speed of 10000 rpm for 15 minutes, the centrifugal temperature was controlled at 10°C, and the upper suspension after centrifugation was collected after centrifugation for 3 times to obtain a cellulose nanocrystal suspension; the CNC suspension was concentrated to 6 wt% by rotary evaporation.

[0043] (3) The CNC suspension of step (2) was mixed with 3 wt% citric acid solution and 12 wt% silica dispersion (diameter 70 nm) in a volume ratio of 10:1:3, and then stirred at 350 rpm for 4 h and ultrasonically treated at an ultrasonic frequency of 40 kHz for 7 min to obtain a CNC / citric acid / silica mixture.

[0044] (4) The CNC / citric acid / silicon dioxide mixture obtained in step (3) is placed on a flat heater for drying. The drying is performed by alternating drying. The alternating drying temperatures are 25° C. and 50° C., respectively. The alternating drying time is 5 min at each temperature. The drying environment humidity is controlled at RH60-70%. The alternating drying is performed until the mixture is dried to form a film, thereby obtaining a non-iridescent film having a long-range disordered / short-range ordered structure.

[0045] The sample film obtained in this example has the same reflection peak as high as 42 nm within a 45° viewing angle, proving that the film sample has non-iridescent characteristics.

[0046] Example 2

[0047] A non-iridescent film having a long-range disorder / short-range order structure and a preparation method thereof, comprising the following steps:

[0048] (1) Pre-treat the hardwood pulp in a NaOH solution with a pH of 9 for 12 h, and then dry and dehydrate it. Mix 100 g of the pre-treated hardwood pulp with 100 ml of 64 wt% concentrated sulfuric acid, and heat the mixture at a stirring rate of 1000 rpm and a temperature of 50°C for 30 min. Then, add 1000 ml of deionized water, mix well, and let it stand for 24 h to terminate the reaction.

[0049] (2) The mixed solution of step (1) was centrifuged at a speed of 11000 rpm for 10 min, the centrifugal temperature was controlled at 10°C, and the upper suspension after centrifugation was collected after centrifugation 5 times to obtain a neutral suspension; the neutral suspension was centrifuged at a speed of 11000 rpm for 17 min, the centrifugal temperature was controlled at 10°C, and the upper suspension after centrifugation was collected after centrifugation 3 times to obtain a cellulose nanocrystal suspension; the CNC suspension was concentrated to 7 wt% by rotary evaporation.

[0050] (3) The CNC suspension of step (2) was mixed with 4 wt% citric acid solution and 15 wt% silica dispersion (diameter 100 nm) in a volume ratio of 10:1:3, and then stirred at 350 rpm for 4 h and ultrasonically treated at an ultrasonic frequency of 30 kHz for 7 min to obtain a CNC / citric acid / silica mixture.

[0051] (4) The CNC / citric acid / silicon dioxide mixture obtained in step (3) is placed on a flat heater for drying. The drying is performed by alternating drying. The alternating drying temperatures are 25° C. and 50° C., respectively. The alternating drying time is 5 minutes at each temperature. The drying environment humidity is controlled at RH60-70% until the mixture is dried to form a film, thereby obtaining the non-iridescent film having a long-range disordered / short-range ordered structure.

[0052] The sample obtained in this example has the same reflection peak up to 50 nm within a 45° viewing angle, proving that the film sample has non-iridescent characteristics.

[0053] Example 3

[0054] A non-iridescent film having a long-range disorder / short-range order structure and a preparation method thereof, comprising the following steps:

[0055] (1) Pre-treat the hardwood pulp in a NaOH solution with a pH of 9 for 12 h, and then dry and dehydrate it. Mix 100 g of the pre-treated hardwood pulp with 100 ml of 66 wt% concentrated sulfuric acid, and heat-treat it at a stirring rate of 1000 rpm and a temperature of 45°C for 40 min. Then, add 1000 ml of deionized water, mix well, and let it stand for 24 h to terminate the reaction.

[0056] (2) The mixed solution of step (1) was centrifuged at a speed of 12000 rpm for 10 min, the centrifugal temperature was controlled at 10°C, and the upper suspension after centrifugation was collected after centrifugation 5 times to obtain a neutral suspension; the neutral suspension was centrifuged at a speed of 10000 rpm for 17 min, the centrifugal temperature was controlled at 10°C, and the upper suspension after centrifugation was collected after centrifugation 3 times to obtain a cellulose nanocrystal suspension; the CNC suspension was concentrated to 8 wt% by rotary evaporation.

[0057] (3) The CNC suspension of step (2) was mixed with 3 wt% citric acid solution and 12 wt% silica dispersion (diameter 120 nm) in a volume ratio of 10:1:3, and then stirred at 350 rpm for 4 h and ultrasonically treated at an ultrasonic frequency of 30 kHz for 7 min to obtain a CNC / citric acid / silica mixture.

[0058] (4) The CNC / citric acid / silicon dioxide mixture obtained in step (3) is placed on a flat heater for drying. The drying is performed by alternating drying. The alternating drying temperatures are 25° C. and 50° C., respectively. The alternating drying time is 5 minutes at each temperature. The drying environment humidity is controlled at RH60-70% until the mixture is dried to form a film, thereby obtaining the non-iridescent film having a long-range disordered / short-range ordered structure.

[0059] The sample obtained in this example has the same reflection peak up to 40 nm within a 45° viewing angle, proving that the film sample has non-iridescent characteristics.

[0060] Comparative Example 1

[0061] A method for preparing a CNC / citric acid composite film without adding silicon dioxide comprises the following steps:

[0062] (1) Pre-treat the hardwood pulp in a NaOH solution with a pH of 9 for 12 h, and then dry and dehydrate it. Mix 100 g of the pre-treated hardwood pulp with 100 ml of 66 wt% concentrated sulfuric acid, and heat-treat it at a stirring rate of 1000 rpm and a temperature of 45°C for 40 min. Then, add 1000 ml of deionized water, mix well, and let it stand for 24 h to terminate the reaction.

[0063] (2) The mixed solution of step (1) was centrifuged at a speed of 12000 rpm for 10 min, the centrifugal temperature was controlled at 10°C, and the upper suspension after centrifugation was collected after centrifugation 5 times to obtain a neutral suspension; the neutral suspension was centrifuged at a speed of 10000 rpm for 17 min, the centrifugal temperature was controlled at 10°C, and the upper suspension after centrifugation was collected after centrifugation 3 times to obtain a cellulose nanocrystal suspension; the CNC suspension was concentrated to 8 wt% by rotary evaporation.

[0064] (3) The CNC suspension of step (2) was mixed with 3 wt% citric acid in a volume ratio of 10:1, and then stirred at 350 rpm for 4 h and then ultrasonically treated at an ultrasonic frequency of 30 kHz for 7 min to obtain a CNC / citric acid mixture.

[0065] (4) The CNC / citric acid mixture of step (3) is placed on a flat heater for drying. The drying is alternating drying. The alternating drying temperatures are 25°C and 50°C, respectively. The alternating drying time at each temperature is 5 minutes. The drying environment humidity is controlled at RH60-70% until the mixture is dried to form a film, thereby obtaining an iridescent film with a long-range ordered / short-range ordered structure.

[0066] Since the sample obtained in this comparative example did not add the long-range structure regulator - silica, the relevant film sample showed a reflection peak shift of 46nm within the 45° observation viewing angle range, proving that the film sample still has a strong iridescent signal.

[0067] Comparative Example 2

[0068] A method for preparing a CNC / silicon dioxide composite film without adding citric acid comprises the following steps:

[0069] (1) Pre-treat the hardwood pulp in a NaOH solution with a pH of 9 for 12 h, and then dry and dehydrate it. Mix 100 g of the pre-treated hardwood pulp with 100 ml of 66 wt% concentrated sulfuric acid, and heat-treat it at a stirring rate of 1000 rpm and a temperature of 45°C for 40 min. Then, add 1000 ml of deionized water, mix well, and let it stand for 24 h to terminate the reaction.

[0070] (2) The mixed solution of step (1) was centrifuged at a speed of 12000 rpm for 10 min, the centrifugal temperature was controlled at 10°C, and the upper suspension after centrifugation was collected after centrifugation 5 times to obtain a neutral suspension; the neutral suspension was centrifuged at a speed of 10000 rpm for 17 min, the centrifugal temperature was controlled at 10°C, and the upper suspension after centrifugation was collected after centrifugation 3 times to obtain a cellulose nanocrystal suspension; the CNC suspension was concentrated to 8 wt% by rotary evaporation.

[0071] (3) The CNC suspension of step (2) was mixed with 12 wt% silica dispersion (diameter 100 nm) in a volume ratio of 10:3, and then stirred at 350 rpm for 4 h and ultrasonically treated at an ultrasonic frequency of 30 kHz for 7 min to obtain a CNC / silica mixture.

[0072] (4) The CNC / silicon dioxide mixture obtained in step (3) is placed on a flat heater for drying. The drying is performed by alternating drying. The alternating drying temperatures are 25° C. and 50° C., respectively. The alternating drying time is 5 minutes at each temperature. The drying environment humidity is controlled at RH60-70%, until the mixture is dried to form a film, thereby obtaining the iridescent film having a long-range ordered / short-range ordered structure.

[0073] Since the sample obtained in this comparative example did not add the short-range structure curing agent - citric acid, the relevant film sample showed a reflection peak shift of 34nm within the 45° observation viewing angle range, proving that the film sample still has a strong iridescent signal.

[0074] Comparative Example 3

[0075] A method for preparing a film without using an alternating drying method comprises the following steps:

[0076] (1) Pre-treat the hardwood pulp in a NaOH solution with a pH of 9 for 12 h, and then dry and dehydrate it. Mix 100 g of the pre-treated hardwood pulp with 100 ml of 62 wt% concentrated sulfuric acid, and heat the mixture at a stirring rate of 1000 rpm and a temperature of 55°C for 20 min. Then, add 1000 ml of deionized water, mix well, and let it stand for 22 h to terminate the reaction.

[0077] (2) The mixed solution of step (1) was centrifuged at a speed of 12000 rpm for 9 minutes, the centrifugal temperature was controlled at 10°C, and the upper suspension after centrifugation was collected after centrifugation after 5 centrifugation to obtain a neutral suspension; the neutral suspension was centrifuged at a speed of 10000 rpm for 15 minutes, the centrifugal temperature was controlled at 10°C, and the upper suspension after centrifugation was collected after centrifugation after 3 centrifugation to obtain a cellulose nanocrystal suspension; the CNC suspension was concentrated to 6 wt% by rotary evaporation.

[0078] (3) The CNC suspension of step (2) was mixed with 3 wt% citric acid and 12 wt% silica (diameter 70 nm) in a volume ratio of 10:1:3, and then stirred at 350 rpm for 4 h and ultrasonically treated at an ultrasonic frequency of 40 kHz for 7 min to obtain a CNC / citric acid / silica mixture.

[0079] (4) The CNC / citric acid / silicon dioxide mixture obtained in step (3) is placed on a flat heater for drying at a constant drying temperature of 35° C. and a drying ambient humidity of RH 60-70% until the mixture is dried to form a film, thereby obtaining the iridescent film having a long-range ordered / short-range ordered structure.

[0080] Since the sample obtained in this comparative example did not use the alternating drying method, the relevant film sample showed a reflection peak shift of 55 nm within a 45° observation viewing angle, proving that the film sample still had a strong iridescent signal.

[0081] Figure 1 The transmission spectra of the film sample obtained in Example 1 at angles of 90° and 45° are shown. It can be clearly seen from the figure that the film sample has the same reflection peak of up to 42nm within the 45° observation viewing angle range, proving that the film sample has non-iridescent characteristics. Figure 2 This is the microscopic morphology of the sample obtained in Example 1. Figure 3 The transmission spectra of the film sample obtained in Comparative Example 1 at angles of 90° and 45° are shown. Since the long-range structure regulator - silica is not added, the relevant film sample shows a reflection peak shift of 46nm within the 45° observation viewing angle range, proving that the film sample still has a strong iridescent signal. Figure 4 The transmission spectra of the film sample obtained in Comparative Example 2 at angles of 90° and 45° are shown. Since the short-range structure curing agent - citric acid is not added, the relevant film sample shows a reflection peak shift of 34nm within the 45° observation viewing angle range, proving that the film sample still has a strong iridescent signal.

[0082] The non-iridescent film is achieved through a long-range disorder / short-range order structure. When observed at different angles through the transmission spectrum, the migration of the reflection peak indicates iridescence. If the reflection peaks overlap, it is non-iridescent.

[0083] The above embodiments are only preferred implementation modes of the present invention and are only used to explain the present invention rather than to limit the present invention. Any changes, substitutions, modifications, etc. made by those skilled in the art without departing from the spirit of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for preparing a non-iridescent film having a long-range disorder / short-range order structure, characterized in that: The steps include: 1) mixing nanocrystalline cellulose, citric acid, and nanoparticles in water to obtain a CNC / citric acid / nanoparticle mixture; 2) drying the CNC / citric acid / nanoparticle mixture at alternating temperatures to form a film to obtain a non-iridescent film; Step 2) The alternating drying temperatures are 20-30°C and 50-55°C, the alternating drying time at each temperature is 3-10 minutes, and the drying environment humidity is 40-70%; In step 1), the mass ratio of nanocrystalline cellulose: citric acid: nanoparticles is (12-60):1:(5-30); The nanoparticles are spherical in shape and have a diameter of 50-500 nm.

2. The method for preparing a non-iridescent film having a long-range disorder / short-range order structure according to claim 1, characterized in that: The alternating drying specifically refers to drying at 20-30°C for 3-10 minutes, then drying at 50-55°C for 3-10 minutes, and alternately drying until a film is formed; The mass ratio of nanocrystalline cellulose: citric acid: nanoparticles is (15-50):1:(7.5-22.5); The length size of nanocrystalline cellulose is 400-600 nm; The diameter of the nanoparticles is 70-120 nm; the nanoparticles are silicon dioxide or titanium dioxide.

3. The method for preparing a non-iridescent film having a long-range disorder / short-range order structure according to claim 2, wherein: During the alternating drying, the drying time is 4 to 6 minutes.

4. The method for preparing a non-iridescent film having a long-range disorder / short-range order structure according to claim 1, wherein: The specific steps of step 1) are as follows: mixing the nanocrystalline cellulose suspension, the citric acid solution and the nanoparticle dispersion; the solvent in the citric acid solution and the nanoparticle dispersion is water; Or the amount of each substance is expressed in terms of concentration and volume, The concentration of the nanocrystalline cellulose suspension, i.e., the cellulose nanocrystal suspension, is 6-10 wt %; the concentration of the citric acid solution is 2-4 wt %; and the concentration of the nanoparticle dispersion is 10-15 wt %; The volume ratio of the nanocrystalline cellulose suspension: the citric acid solution: the nanoparticle dispersion is (8-12): 1: (2-4).

5. The method for preparing a non-iridescent film having a long-range disorder / short-range order structure according to claim 4, wherein: The volume ratio of the nanocrystalline cellulose suspension: the citric acid solution: the nanoparticle dispersion is 10:1:

3.

6. The method for preparing a non-iridescent film having a long-range disorder / short-range order structure according to claim 1, wherein: The nanocrystalline cellulose suspension is obtained by treating hardwood pulp with concentrated sulfuric acid; The mixing in step 1) refers to stirring first and then ultrasonic treatment; the stirring speed is 300-400 rpm, the stirring time is 3-4 hours, the ultrasonic treatment time is 5-7 minutes, and the ultrasonic frequency of the ultrasonic treatment is 20-40KHz.

7. The method for preparing a non-iridescent film having a long-range disorder / short-range order structure according to claim 6, wherein: The nanocrystalline cellulose suspension is specifically obtained by the following method: a) pre-treating hardwood pulp in a weak alkaline environment, followed by drying and dehydration; mixing the pre-treated hardwood pulp with concentrated sulfuric acid, heating the mixture under stirring, adding water to terminate the reaction, mixing and standing the mixture, centrifuging, and collecting the upper suspension to obtain a suspension; b) centrifuging the suspension, taking the upper suspension, and diluting it to obtain a nanocrystalline cellulose suspension.

8. The method for preparing a non-iridescent film having a long-range disorder / short-range order structure according to claim 7, wherein: The pH of the weak alkaline environment of the pretreatment of the hardwood pulp in step a) is 8.5 to 9.5, provided by NaOH solution and KOH solution, and the pretreatment time is 10 to 14 hours; The concentration of the concentrated sulfuric acid solution in step a) is 62-66 wt %, and the mass volume ratio of the pretreated hardwood pulp to the concentrated sulfuric acid is 1 g: (1-8) mL; The stirring speed in step a) is 1000-1200 rpm, the heating temperature is 40-55° C., and the heating time is 20-40 min; In step a), the volume ratio of concentrated sulfuric acid to water for terminating the reaction is 1:(9-12); the standing time is 20 to 24 hours; The number of centrifugation in step a) is 5 to 6 times, the centrifugal speed is 10,000 to 12,000 rpm, the centrifugal time is 8 to 10 minutes, and the centrifugal temperature is 10 to 15°C; The number of centrifugation in step b) is 3 to 4 times, the centrifugal speed is 10,000 to 11,000 rpm, the centrifugal time is 15 to 20 minutes, and the centrifugal temperature is 10 to 15°C.

9. A non-iridescent film having a long-range disorder / short-range order structure obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the non-iridescent film having a long-range disorder / short-range order structure according to claim 9, characterized in that: The non-iridescent film having a long-range disorder / short-range order structure is used as a structural color marker for wide viewing angle display.

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