Hydroxypropyl cellulose structural color organic gel as well as preparation method and application thereof

Abstract

The invention discloses a hydroxy propyl cellulose structural color organic gel and a preparation method and application thereof.The preparation method comprises the following steps that S1, hydroxy propyl cellulose, an organic solvent with the boiling point higher than 150 DEG C, acrylic acid or acrylate monomers, a photoinitiator and the like are dispersed in a volatile solvent, after the volatile solvent volatilizes, full stirring is conducted, and the organic gel is obtained; standing for a period of time to obtain hydroxy propyl cellulose liquid crystal based organic gel pregel; and S2, carrying out light curing on the hydroxy propyl cellulose liquid crystal base pregel to obtain the hydroxy propyl cellulose structural color organic gel. The preparation method provided by the invention has the advantages of simple operation, strong operability and the like, overcomes the defect of short color retention time of a hydroxy propyl cellulose structural color hydrogel material under a non-closed condition, and can be applied to sensing, display, bionic skin, optical information storage / encryption, anti-counterfeiting, 3D printing and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a hydroxypropyl cellulose structural color organic gel and a preparation method and application thereof. Background Art

[0002] Hydroxypropylcellulose (HPC), produced by the etherification reaction of cellulose and propylene oxide, is a non-ionic water-soluble cellulose derivative and one of the most important derivatives of cellulose, the most abundant renewable polymer material in the biosphere. It has the advantages of low price, non-toxicity, and biodegradability. HPC can quickly self-assemble in a certain concentration (>50wt%) of aqueous solution to form cholesteric solubility liquid crystals with a periodic helical structure, and show bright structural colors with metallic luster.

[0003] In recent years, HPC cholesteric-based structural color hydrogel materials have shown great application potential in the fields of sensing, information storage, electronic devices and 3D printing. However, in a non-closed system, due to the volatile water, the helical pitch is continuously shortened, and the structural color of HPC-based hydrogels will gradually shift to blue until it disappears.

[0004] In summary, the structural color of HPC-based hydrogels cannot be preserved for a long time in a non-closed system, and the color persistence and stability are poor. At present, there is a lack of a simple, efficient material preparation method based on hydroxypropyl cellulose cholesteric phase that can preserve structural color for a long time in a non-closed system. Summary of the invention

[0005] The present invention aims to provide a hydroxypropyl cellulose structural color organogel and a preparation method and application thereof, which can overcome the problems that the structural color of HPC-based hydrogel cannot be preserved for a long time in a non-closed system and the color persistence and stability are poor.

[0006] According to one aspect of the present invention, there is provided a method for preparing a hydroxypropyl cellulose structural color organogel, comprising the following steps: S1: dispersing hydroxypropyl cellulose, an organic solvent having a boiling point higher than 150°C, a black light-absorbing substance, acrylic acid or an acrylate monomer and a photoinitiator in a volatile solvent; after the volatile solvent evaporates, stirring the mixture sufficiently, and standing the mixture for a period of time to obtain a hydroxypropyl cellulose liquid crystal-based organogel pregel; S2: photocuring the hydroxypropyl cellulose liquid crystal-based pregel to obtain the hydroxypropyl cellulose structural color organogel.

[0007] Preferably, in the hydroxypropyl cellulose liquid crystal-based organogel pre-gel, the mass proportion of the hydroxypropyl cellulose is 40% to 70%, and the mass proportion of the organic solvent having a boiling point higher than 150° C. is 2% to 50%.

[0008] Preferably, in the hydroxypropyl cellulose liquid crystal-based organogel pre-gel, the mass proportion of the black light-absorbing substance is 0% to 0.5%, and the mass proportion of the acrylic acid or acrylate monomer is 0% to 60%.

[0009] Preferably, the organic solvent with a boiling point higher than 150° C. comprises one or more of the following: monohydric alcohol substances, including heptanol, octanol, nonanol and decanol; dihydric alcohol substances, including ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol and decanediol; polyhydric alcohol substances, including glycerol and pentaerythritol; high boiling point organic polar substances, including dimethyl sulfoxide, dimethylformamide and N-methyl-2-pyrrolidone.

[0010] Preferably, the black light-absorbing material includes one or more of the following: graphite powder, carbon black, carbon nanotubes, graphene, graphene oxide, amorphous carbon, polydopamine, polythiophene, polypyrrole, polyaniline or MXene.

[0011] Preferably, the acrylic acid or acrylate monomer comprises one or more of the following: ethoxyethoxyethyl acrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, diethylene glycol dimethacrylate, dipropylene glycol diacrylate, triethylene glycol dimethacrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethyl triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, di-trimethylolpropane tetraacrylate and dipentaerythritol penta- / hexyl-acrylic acid.

[0012] Preferably, in the hydroxypropyl cellulose liquid crystal-based organic gel pre-gel, the mass proportion of the photoinitiator is 0% to 2%; the photoinitiator includes one or more of the following: benzophenone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-4-(2-hydroxyethoxy)-2-methylpropiophenone, 1,1'-(methylenedi-4,1-phenylene)bis(2-hydroxy-2-methyl-1-propanone), 2,2-dimethoxy-2-phenylacetophenone, isopropylthioxanthone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, phenyl-2,4,6-trimethylbenzoyl lithium phosphite and diphenyl-(4-phenylthio)phenylsulfonium hexafluoroantimonate.

[0013] Preferably, the color of the hydroxypropyl cellulose structural color organic gel is adjusted by the concentration of the hydroxypropyl cellulose, the type and concentration of the organic solvent with a boiling point higher than 150°C, and the type and concentration of the acrylic acid or acrylate monomer; the color saturation of the hydroxypropyl cellulose structural color organic gel is adjusted by the concentration of the black light-absorbing substance; the hydroxypropyl cellulose liquid crystal based pregel is made into a film, fiber or a 2D or 3D structure with a special shape by spinning, casting, calendering, drip coating, spin coating, suspension coating, scraping, engraving, extrusion, stamping, mold forming or 3D printing; after the hydroxypropyl cellulose structural color organic gel is processed and shaped, the static self-assembly time is 0 to 120 minutes; the light curing time is 0 to 120 minutes of illumination under ultraviolet light.

[0014] According to another aspect of the present invention, there is provided a hydroxypropyl cellulose structural color organogel prepared according to the aforementioned method.

[0015] According to another aspect of the present invention, there is provided an application of a hydroxypropyl cellulose structural color organogel prepared according to the aforementioned method, which is applied in the fields of sensing, display, bionic skin, optical information storage / encryption, anti-counterfeiting, mold forming and 3D printing.

[0016] The present invention discloses a hydroxypropyl cellulose structural color organic gel and its preparation method and application. The preparation method comprises the following steps: S1: dispersing hydroxypropyl cellulose, an organic solvent with a boiling point higher than 150°C, a black light-absorbing substance, acrylic acid or acrylate monomers and a photoinitiator in a volatile solvent, and after the volatile solvent evaporates, fully stirring, and standing for a period of time to obtain a hydroxypropyl cellulose liquid crystal-based organic gel pre-gel; S2: photocuring the hydroxypropyl cellulose liquid crystal-based pre-gel to obtain the hydroxypropyl cellulose structural color organic gel. The preparation method provided by the present invention has the advantages of simple operation and strong operability, overcomes the disadvantage of short color retention time of hydroxypropyl cellulose structural color hydrogel materials under non-closed conditions, and is expected to be applied to sensing, display, bionic skin, optical information storage / encryption, anti-counterfeiting and 3D printing. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0018] Figure 1 This is a comparison chart of the retention time of a hydroxypropyl cellulose organic system and a water system having structural color according to an embodiment of the present invention;

[0019] Figure 2 A system diagram of a hydroxypropyl cellulose structural color organogel with mechanochromic properties according to an embodiment of the present invention;

[0020] Figure 3 A system diagram of a hydroxypropyl cellulose structural color organogel with thermochromic properties according to an embodiment of the present invention;

[0021] Figure 4 A system diagram of a gas-driven hydroxypropyl cellulose structural color organogel with color-changing properties according to an embodiment of the present invention;

[0022] Figure 5 A system diagram of an electrically driven hydroxypropyl cellulose structural color organogel with color-changing properties according to an embodiment of the present invention;

[0023] Figure 6 The photographs and reflectance spectra of hydroxypropyl cellulose structural color organogels with different colors according to embodiments of the present invention (0.3g HPC+0.04g, 0.05g or 0.06g 1,3PP; 0.1g (TEGDMA:1173=100:4);

[0024] Figure 7 The photographs and reflectance spectra of hydroxypropyl cellulose structural color organogels with different colors according to embodiments of the present invention (0.3g HPC+0.06g, 0.07g or 0.08g 1,3PP; 0.1g (TPGDA:1173=100:4);

[0025] Figure 8 The photographs and reflectance spectra of hydroxypropyl cellulose structural color organogels with different colors according to the embodiments of the present invention (0.3g HPC+0.05g, 0.06g or 0.07g 1,3PP; 0.1g (TMPTA:1173=100:4);

[0026] Fig. 9 The color patterns and shapes 3D printed using hydroxypropyl cellulose structural color organogel pre-gel according to an embodiment of the present invention;

[0027] Fig.10 The colorful letter patterns and shapes are produced by molding the hydroxypropyl cellulose structural color organogel pre-gel according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0029] The present invention belongs to the technical field of polymer materials. Specifically, a hydroxypropyl cellulose structural color organogel and a preparation method and application thereof are disclosed. The preparation method comprises: (1) dispersing hydroxypropyl cellulose (HPC), a high boiling point organic solvent (boiling point>150°C), acrylic acid or acrylate monomer, a photoinitiator, a black light-absorbing substance, etc. in ethanol or water solvent (volatile solvent), and uniformly mixing them in a certain proportion, slowly volatilizing at room temperature, and self-assembling into cholesteric liquid crystal; (2) photocuring the above hydroxypropyl cellulose liquid crystal-based organogel pregel by light irradiation to generate a hydroxypropyl cellulose structural color organogel with bright structural color.

[0030] The purpose of the present invention is to solve the problems that the structural color of HPC-based hydrogel cannot be preserved for a long time in a non-closed system, and the color persistence and stability are poor. By replacing the water solvent with an organic solvent with a high boiling point and low volatility, and screening out acrylic acid or acrylate monomers compatible with the HPC organic solvent system, a simple and efficient preparation method of hydroxypropyl cellulose structural color organogel is provided, which has important research significance and practical application value in sensing, display, bionic skin, optical information storage / encryption, anti-counterfeiting, mold forming and 3D printing.

[0031] In the prior art, by adding gelling agents, acrylic acid or acrylate monomers, physical crosslinking or chemical crosslinking is enhanced, the processability and mechanical properties of HPC-based hydrogels are improved, and the application scenarios of structural color HPC-based hydrogels are significantly improved. However, due to the volatilization of water, the structural color of HPC-based hydrogels cannot be maintained for a long time in a non-closed system, which limits its potential in long-term applications. In addition, the HPC structural color hydrogel materials in the prior art still have the problem of incompatibility with some hydrophobic acrylic acid or acrylate monomers and photoinitiators, which limits their processing performance and further affects the mechanical properties of the material and its application in various fields.

[0032] Compared with the prior art, the present invention utilizes room temperature volatilization to obtain a photocurable hydroxypropyl cellulose liquid crystal-based organogel pregel by mixing a low-concentration hydroxypropyl cellulose solution, a high-boiling-point and low-volatility organic solvent, and acrylic acid or acrylate monomers (containing a photoinitiator).

[0033] The method for preparing the hydroxypropyl cellulose structural color organogel provided by the present invention has the advantages of simple operation, convenience, high efficiency, strong operability, etc., and overcomes the disadvantages of the hydroxypropyl cellulose structural color hydrogel material under non-sealed conditions, such as short color retention time due to water volatilization, and incompatibility with some relatively hydrophobic acrylic monomers and photoinitiators. The hydroxypropyl cellulose structural color organogel prepared by the present invention has the advantages of good color persistence and stability, strong processability, and can be processed into various colors and shapes according to needs, and has broad application prospects in the fields of sensing, display, bionic skin, optical information storage / encryption, anti-counterfeiting, mold forming and 3D printing.

[0034] Reference will now be made in detail to various embodiments of the present invention, examples of which are shown in the accompanying drawings and described below. For ease of interpretation and precise definition in the appended claims, the terms "upper", "lower", "inner" and "outer" are used to describe features of the exemplary embodiments shown in the drawings with reference to their positions.

[0035] Embodiment 1:

[0036] This example demonstrates the retention time comparison between the hydroxypropyl cellulose structural color organic system and the water system having structural color, and verifies that the structural color of the hydroxypropyl cellulose organic system can be retained for a long time under non-sealed conditions.

[0037] (1) Weigh 1.5 g of hydroxypropyl cellulose solid powder, 0.75 g of ultrapure water (H2O) and 75 ul of graphene aqueous dispersion (graphene content 1 mg / ml), stir thoroughly, mix evenly, seal and store, and let stand for a period of time until a cholesteric HPC aqueous solution sample with structural color is obtained;

[0038] (2) preparing a hydroxypropyl cellulose dilute solution: weighing 30.0 g of hydroxypropyl cellulose and 70.0 g of ethanol to prepare a 30 wt % hydroxypropyl cellulose dilute solution;

[0039] (3) Weigh 1.0 g of hydroxypropyl cellulose dilute solution (30 wt%), 0.08 g of 1,3-propylene glycol (1,3PP), and 38 ul of graphene ethanol dispersion (graphene content 1 mg / ml), mix them evenly, and slowly evaporate them at room temperature to obtain a cholesteric HPC organic solution sample with structural color;

[0040] (4) The reflectance spectra of the hydroxypropyl cellulose structural color organic system and the water system were measured over time, and the relationship between the spectral peak and time was taken, demonstrating the advantage of the cellulose organic system's structural color being able to be retained for a long time under non-sealed conditions. Figure 1 As shown, the retention time comparison between the hydroxypropyl cellulose organic system and the water system with structural color is demonstrated.

[0041] Embodiment 2:

[0042] This embodiment provides an application of a hydroxypropyl cellulose structural color organogel, comprising the following preparation steps:

[0043] (1) preparing a hydroxypropyl cellulose dilute solution: weighing 30.0 g of hydroxypropyl cellulose and 70.0 g of ethanol to prepare a 30 wt % hydroxypropyl cellulose dilute solution;

[0044] (2) Weighing 1.0 g of hydroxypropyl cellulose dilute solution (30 wt%) and 0.12 g of ethylene glycol (EG), mixing them evenly and slowly volatilizing them at room temperature to obtain a cholesteric HPC sample with structural color;

[0045] (3) The HPC sample with structural color was coated on a VHB5952 substrate, and a layer of VHB 4910 or polydimethylsiloxane was attached to the HPC film to prepare a mechanochromic device.

[0046] (4) The mechanochromic device was fixed to a vernier caliper and stretched. Through real-time photography, it can be seen that as the stretching rate increases, the structural color of the mechanochromic device undergoes a significant blue shift, demonstrating its potential application in mechanical sensing. Figure 2 Shown is a system diagram of hydroxypropyl cellulose structural color organogel with mechanochromic properties.

[0047] Embodiment 3:

[0048] This embodiment provides an application of a hydroxypropyl cellulose structural color organogel, comprising the following preparation steps:

[0049] (1) preparing a hydroxypropyl cellulose dilute solution: weighing 30.0 g of hydroxypropyl cellulose and 70.0 g of ethanol to prepare a 30 wt % hydroxypropyl cellulose dilute solution;

[0050] (2) Weighing 1.0 g of hydroxypropyl cellulose dilute solution (30 wt%) and 0.06 g of ethylene glycol (EG), mixing them evenly and slowly volatilizing them at room temperature to obtain a cholesteric HPC sample with structural color;

[0051] (3) Uncured Ecoflex 00-31 silicone (the mass ratio of part A to part B is 1:1) or a silicone system with a similar formulation is drop-coated on a VHB4930 double-sided tape and then scraped to a thickness of about 0.1 mm. After being placed at room temperature overnight, it is further cured at 80°C for 2 hours. A thermochromic coating (polyvinyl alcohol 8-88, 65°C thermochromic powder and carbon black in a mass ratio of 10:80:1) is spin-coated on the other side of the VHB4930 double-sided tape and allowed to stand to dry. Subsequently, a layer of VHB4910 is adhered to the VHB4930 film coated with the thermochromic coating, and a HPC sample with structural color is coated on the VHB4910 substrate. Finally, a layer of VHB 4910 is adhered to the film coated with HPC for sealing to prepare a thermochromic device.

[0052] (4) The thermochromic device was placed on a hot stage and different temperatures were set. The temperature was reached for 5 minutes. After the color of the thermochromic device stabilized, it was observed. It can be seen that when the temperature increased from 25°C to 65°C, the structural color of the thermochromic device attached with HPC changed significantly, demonstrating its potential application in thermal sensing. Figure 3 Shown is a system diagram of hydroxypropyl cellulose structural color organogel with thermochromic properties.

[0053] Embodiment 4:

[0054] This embodiment provides an application of a hydroxypropyl cellulose structural color organogel, comprising the following preparation steps:

[0055] (1) Preparation of pneumatic elastomer actuator: Polymethylsiloxane Ecoflex 00-31 (20 g) was used as the base, and after a film was formed on its surface, vacuum grease was applied to the center area; then, uncured Ecoflex 00-31 (5 g, containing 0.5% carbon black) was poured onto the Ecoflex 00-31 containing vacuum grease as the top layer, and waited for it to be completely cured; a syringe was introduced from the side, and the needle was inserted into the vacuum grease cavity of the cured device to verify that it can be used as a pneumatic elastomer actuator.

[0056] (2) Coating a cholesteric liquid crystal system with structural color onto the carbon black layer of the pneumatic elastomer actuator and waiting for it to self-assemble again until structural color appears, such as Figure 4 As shown in A.

[0057] (3) Preparation of cholesteric liquid crystal system: (a) Preparation of hydroxypropyl cellulose dilute solution: Weigh 30.0 g hydroxypropyl cellulose and 70.0 g ethanol to prepare a 30 wt % hydroxypropyl cellulose dilute solution; (b) Weigh 1.0 g hydroxypropyl cellulose dilute solution (30 wt %), 0.10 g 1,3-propylene glycol, and 40 ul graphene dispersion (graphene content 1 mg / ml), mix them evenly and evaporate them slowly at room temperature, then stir and let stand until the hydroxypropyl cellulose in the pre-gel self-assembles into a cholesteric liquid crystal system with structural color, such as Figure 4 As shown in sample B; (c) weighing 1.0g of hydroxypropyl cellulose dilute solution (30wt%), 0.06g of 1,3-propylene glycol, 0.01g of trimethylolpropane triacrylate (TMPTA, containing 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173), the mass ratio of TMPTA to 1173 is 100:4), and 40ul of graphene dispersion (graphene content 1mg / ml), mixing them evenly and slowly evaporating them at room temperature, then stirring and standing until the hydroxypropyl cellulose in the pre-gel self-assembles into a cholesteric liquid crystal system with structural color, as shown in FIG. Figure 4 C sample; (d) weighing 1.0g of hydroxypropyl cellulose dilute solution (30wt%), 0.06g of 1,3-propylene glycol, 0.05g of trimethylolpropane triacrylate (TMPTA, containing 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173), the mass ratio of TMPTA to 1173 is 100:4), and 40ul of graphene dispersion (graphene content 1mg / ml), mixing them evenly and slowly evaporating them at room temperature, then stirring and standing until the hydroxypropyl cellulose in the pre-gel self-assembles into a cholesteric liquid crystal system with structural color, as shown in FIG. Figure 4 D sample; (e) weighing 1.0g of hydroxypropyl cellulose dilute solution (30wt%), 0.06g of 1,3-propylene glycol, 0.10g of trimethylolpropane triacrylate (TMPTA, containing 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173), the mass ratio of TMPTA to 1173 is 100:4), and 40ul of graphene dispersion (graphene content 1mg / ml), mixing them evenly and slowly evaporating them at room temperature, then stirring and standing until the hydroxypropyl cellulose in the pre-gel self-assembles into a cholesteric liquid crystal system with structural color, as shown in FIG. Figure 4 Sample E is shown.

[0058] (4) Using hydroxypropyl cellulose pregel as ink, write numbers on the pneumatic elastomer actuator. After the cholesteric liquid crystal system reassembles to produce structural colors, use an ultraviolet light source to irradiate the pregel containing the monomers to crosslink it into a hydroxypropyl cellulose structural color organic gel with structural colors.

[0059] (5) The pneumatic elastomer actuator is inflated with air through a syringe to cause it to deform. It can be seen that as the volume of gas increases, the structural color of the cholesteric liquid crystal system attached to the pneumatic elastomer actuator undergoes a significant blue shift; as the monomer content in the pre-gel increases, the degree of structural color change of the cholesteric liquid crystal system attached to the pneumatic elastomer actuator decreases, demonstrating its application in the field of optical mechanical sensing, such as Figure 4 As shown in BE.

[0060] Embodiment 5:

[0061] This embodiment provides an application of a hydroxypropyl cellulose structural color organogel, comprising the following preparation steps:

[0062] (1) preparing a hydroxypropyl cellulose dilute solution: weighing 30.0 g of hydroxypropyl cellulose and 70.0 g of ethanol to prepare a 30 wt % hydroxypropyl cellulose dilute solution;

[0063] (2) Weigh 1.0 g of hydroxypropyl cellulose dilute solution (30 wt%), 0.05 g of 1,5-pentanediol (0.06 g of 1,5-pentanediol or 0.07 g of 1,5-pentanediol, PD5), and 35 ul of graphene dispersion (graphene content 1 mg / ml), mix them evenly, and slowly evaporate them at room temperature to obtain a slightly sticky HPC sample;

[0064] (3) 200% radial and transverse pre-stretched VHB 4910 was attached to an acrylic frame (inner diameter 8 cm), carbon nanotubes or conductive carbon esters (such as 846-80G from MG Chemicals) were coated on the pre-stretched VHB4910 as electrode materials, and conductive tape was attached to the ends of the carbon nanotubes on the acrylic frame for applying voltage. Subsequently, a layer of 200% radial and transverse pre-stretched VHB 4905 was attached to the VHB4910 film coated with the conductive material to prepare a dielectric elastomer actuator.

[0065] (4) The slightly sticky HPC sample was coated onto the VHB 4905 layer of the dielectric elastomer actuator and allowed to evaporate until structural color appeared.

[0066] (5) When the voltage is applied, it can be seen that when the voltage increases from 3000 V to 5000 V, the structural color of the dielectric elastomer actuator film attached with HPC changes significantly, demonstrating its application in the optoelectronic field, such as optoelectronic sensors and color dynamic display. Figure 5 As shown, a system diagram of electrically driven hydroxypropyl cellulose structural color organogel with color-changing properties is presented.

[0067] Embodiment 6:

[0068] This embodiment provides a method for preparing a hydroxypropyl cellulose structural color organogel, comprising the following steps:

[0069] (1) preparing a hydroxypropyl cellulose dilute solution: weighing 30.0 g of hydroxypropyl cellulose and 70.0 g of ethanol to prepare a 30 wt % hydroxypropyl cellulose dilute solution;

[0070] (2) preparing a hydroxypropyl cellulose liquid crystal-based organogel pregel: weighing 1.0 g of a hydroxypropyl cellulose dilute solution (30 wt%), 0.04 g of 1,3-propylene glycol (0.05 g of 1,3-propylene glycol or 0.06 g of 1,3-propylene glycol, 1,3PP), 0.10 g of triethylene glycol dimethacrylate (TEGDMA, containing 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173), the mass ratio of TEGDMA to 1173 being 100:4), and 45 ul of a graphene dispersion (graphene content 1 mg / ml), mixing them evenly and slowly evaporating them at room temperature;

[0071] (3) stirring and standing until the hydroxypropyl cellulose in the pregel self-assembles into a cholesteric liquid crystal system having a structural color;

[0072] (4) Using an ultraviolet light source to irradiate the self-assembled pregel, the pregel is cross-linked into a hydroxypropyl cellulose structural color organogel with different structural colors, such as Figure 6 Shown are photographs and reflectance spectra of hydroxypropyl cellulose structural color organogels with different colors (0.3g HPC+0.04g, 0.05g or 0.06g 1,3PP; 0.1g (TEGDMA:1173=100:4).

[0073] Embodiment 7:

[0074] This embodiment provides a method for preparing a hydroxypropyl cellulose structural color organogel, comprising the following steps:

[0075] (1) preparing a hydroxypropyl cellulose dilute solution: weighing 30.0 g of hydroxypropyl cellulose and 70.0 g of ethanol to prepare a 30 wt % hydroxypropyl cellulose dilute solution;

[0076] (2) preparing a hydroxypropyl cellulose liquid crystal-based organogel pregel: weighing 1.0 g of a hydroxypropyl cellulose dilute solution (30 wt%), 0.06 g of 1,3-propylene glycol (0.07 g of 1,3-propylene glycol or 0.08 g of 1,3-propylene glycol, 1,3PP), 0.10 g of tripropylene glycol diacrylate (TPGDA, containing 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173), the mass ratio of TPGDA to 1173 being 100:4), and 45 ul of a graphene dispersion (graphene content 1 mg / ml), mixing them evenly and slowly volatilizing them at room temperature;

[0077] (3) stirring and standing until the hydroxypropyl cellulose in the pregel self-assembles into a cholesteric liquid crystal system having a structural color;

[0078] (4) Using an ultraviolet light source to irradiate the self-assembled pregel, the pregel is cross-linked into a hydroxypropyl cellulose structural color organogel with different structural colors, such as Figure 7 Shown are photographs and reflectance spectra of hydroxypropyl cellulose structural color organogels with different colors (0.3g HPC+0.06g, 0.07g or 0.08g 1,3PP; 0.1g (TPGDA:1173=100:4).

[0079] Embodiment 8:

[0080] This embodiment provides a method for preparing a hydroxypropyl cellulose structural color organogel, comprising the following steps:

[0081] (1) preparing a hydroxypropyl cellulose dilute solution: weighing 30.0 g of hydroxypropyl cellulose and 70.0 g of ethanol to prepare a 30 wt % hydroxypropyl cellulose dilute solution;

[0082] (2) preparing a hydroxypropyl cellulose liquid crystal-based organogel pregel: weighing 1.0 g of a hydroxypropyl cellulose dilute solution (30 wt%), 0.05 g of 1,3-propylene glycol (0.06 g of 1,3-propylene glycol or 0.07 g of 1,3-propylene glycol, 1,3PP), 0.10 g of trimethylolpropane triacrylate (TMPTA, containing 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173), the mass ratio of TMPTA to 1173 being 100:4), and 45 ul of a graphene dispersion (graphene content 1 mg / ml), mixing them evenly and slowly volatilizing them at room temperature;

[0083] (3) stirring and standing until the hydroxypropyl cellulose in the pregel self-assembles into a cholesteric liquid crystal system having a structural color;

[0084] (4) Using an ultraviolet light source to irradiate the self-assembled pregel, the pregel is cross-linked into a hydroxypropyl cellulose structural color organogel with different structural colors, such as Figure 8 Shown are photographs and reflectance spectra of hydroxypropyl cellulose structural color organogels with different colors (0.3g HPC+0.05g, 0.06g or 0.07g 1,3PP; 0.1g (TMPTA:1173=100:4)).

[0085] Embodiment 9:

[0086] This embodiment provides an application of a hydroxypropyl cellulose structural color organogel, comprising the following preparation steps:

[0087] (1) preparing a hydroxypropyl cellulose dilute solution: weighing 30.0 g of hydroxypropyl cellulose and 70.0 g of ethanol to prepare a 30 wt % hydroxypropyl cellulose dilute solution;

[0088] (2) Weigh 1.0 g of hydroxypropyl cellulose dilute solution (30 wt%), 0.05 g of 1,4-butanediol (BT4), 0.10 g of trimethylolpropane triacrylate (TMPTA, containing 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173), the mass ratio of TMPTA to 1173 is 100:4), and 45 ul of graphene dispersion (graphene content 1 mg / ml), mix them evenly and evaporate them slowly at room temperature, then stir and stand until the hydroxypropyl cellulose in the pregel self-assembles into a cholesteric liquid crystal system with structural color;

[0089] (3) The pre-gel is filled into a syringe, and the pre-gel filaments are extruded using a 3D printer and a syringe pump to form a designed pattern on a substrate. After the pre-gel filaments are left to stand for a period of time and their color is restored (30 minutes), in-situ photo-crosslinking is performed to form a star-shaped structural color gel, such as Fig. 9 Shown is a color pattern printed using hydroxypropyl cellulose structural color organogel pregel as printing ink.

[0090] Embodiment 10:

[0091] This embodiment provides an application of a hydroxypropyl cellulose structural color organogel, comprising the following preparation steps:

[0092] (1) preparing a hydroxypropyl cellulose dilute solution: weighing 30.0 g of hydroxypropyl cellulose and 70.0 g of ethanol to prepare a 30 wt % hydroxypropyl cellulose dilute solution;

[0093] (2) Weigh 5.0 g of hydroxypropyl cellulose dilute solution (30 wt%), 0.20 g of 1,3-propylene glycol (or 0.25 g of 1,3-propylene glycol, 1,3PP), 0.50 g of trimethylolpropane triacrylate (TMPTA, containing 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173), the mass ratio of TMPTA to 1173 is 100:4), and 220 ul of graphene dispersion (graphene content 1 mg / ml), mix them evenly and evaporate them slowly at room temperature, then stir and stand until the hydroxypropyl cellulose in the pregel self-assembles into a cholesteric liquid crystal system with structural color;

[0094] (3) Fill the pre-gel into the letter mold, flatten it, and let it stand for a while. After its color is restored (30 minutes), it is photo-cross-linked to form a structural color gel with support, such as Fig.10Shown is a colorful letter pattern produced by using hydroxypropyl cellulose structural color organogel pregel as a printing ink mold.

[0095] The above embodiments are only examples for clearly explaining the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description, and these various changes, modifications, substitutions and deformations derived from the principles and spirit of the present invention still fall within the scope of protection of the present invention.

Claims

1. A method for preparing a hydroxypropyl cellulose structural color organogel, characterized in that: The following steps are involved: S1: dispersing hydroxypropyl cellulose, an organic solvent with a boiling point higher than 150° C., a black light-absorbing substance, acrylic acid or an acrylate monomer and a photoinitiator in a volatile solvent, and after the volatile solvent evaporates, stirring the mixture sufficiently, and standing the mixture for a period of time to obtain a hydroxypropyl cellulose liquid crystal-based organogel pre-gel; S2: Photocuring the hydroxypropyl cellulose liquid crystal based pre-gel to obtain the hydroxypropyl cellulose structural color organic gel.

2. The preparation method according to claim 1, characterized in that: In the hydroxypropyl cellulose liquid crystal-based organogel pre-gel, the mass proportion of the hydroxypropyl cellulose is 40% to 70%, and the mass proportion of the organic solvent with a boiling point higher than 150° C. is 2% to 50%.

3. The preparation method according to claim 1, characterized in that: In the hydroxypropyl cellulose liquid crystal-based organogel pre-gel, the mass proportion of the black light-absorbing substance is 0% to 0.5%, and the mass proportion of the acrylic acid or acrylate monomer is 0% to 60%.

4. The preparation method according to claim 2, characterized in that: The organic solvent having a boiling point higher than 150° C. comprises one or more of the following: Monohydric alcohols, including heptanol, octanol, nonanol, and decanol; Diols, including ethylene glycol, propylene glycol, butylene glycol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, and decanediol; Polyols, including glycerol and pentaerythritol; High boiling point organic polar substances, including dimethyl sulfoxide, dimethylformamide and N-methyl-2-pyrrolidone.

5. The preparation method according to claim 3, characterized in that: The black light absorbing material includes one or more of the following: Graphite powder, carbon black, carbon nanotubes, graphene, graphene oxide, amorphous carbon, polydopamine, polythiophene, polypyrrole, polyaniline or MXene.

6. The preparation method according to claim 1, characterized in that: The acrylic acid or acrylate monomers include one or more of the following: Ethoxyethoxyethyl acrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, diethylene glycol dimethacrylate, dipropylene glycol diacrylate, triethylene glycol dimethacrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, di-trimethylolpropane tetraacrylate and dipentaerythritol penta- / hexyl-acrylate.

7. The preparation method according to claim 1, characterized in that: In the hydroxypropyl cellulose liquid crystal-based organogel pre-gel, the mass proportion of the photoinitiator is: 0% to 2%; The photoinitiator includes one or more of the following: Benzophenone, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-4-(2-hydroxyethoxy)-2-methylpropiophenone, 1,1'-(methylenedi-4,1-phenylene)bis(2-hydroxy-2-methyl-1-propanone), 2,2-dimethoxy-2-phenylacetophenone, isopropylthioxanthone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, lithium phenyl-2,4,6-trimethylbenzoylphosphite and diphenyl-(4-phenylthio)phenylsulfonium hexafluoroantimonate.

8. The preparation method according to claim 7, characterized in that: The color of the hydroxypropyl cellulose structural color organogel is adjusted by the concentration of the hydroxypropyl cellulose, the type and concentration of the organic solvent having a boiling point higher than 150° C., and the type and concentration of the acrylic acid or acrylate monomer; The color saturation of the hydroxypropyl cellulose structural color organogel is adjusted by the concentration of the black light absorbing substance; The hydroxypropyl cellulose liquid crystal based pregel is made into a film, fiber or a 2D or 3D structure with a special shape by spinning, casting, calendering, drip coating, spin coating, suspension coating, scraping, engraving, extrusion, embossing, mold forming or 3D printing processing; After the hydroxypropyl cellulose structural color organogel is processed and shaped, the self-assembly time is 0 to 120 minutes; The light curing time is 0 to 120 minutes under ultraviolet light.

9. Hydroxypropyl cellulose structural color organogel prepared by the method according to any one of claims 1 to 8.

10. Use of the hydroxypropyl cellulose structural color organogel prepared by the method according to any one of claims 1 to 8, characterized in that: It is used in the fields of sensing, display, bionic skin, optical information storage / encryption, anti-counterfeiting, mold forming and 3D printing.

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