Polydopamine-coated nanoparticles, preparation method thereof, and structural chromogenic cellulose fabric

Abstract

The present invention discloses a polydopamine-coated nanosphere, which is prepared by the following method: adding dopamine hydrochloride and an iron salt oxidation catalyst to an aqueous dispersion of the nanospheres, mixing well, heating to 30-60°C, and stirring for a reaction of 5-120 minutes to obtain the polydopamine-coated nanospheres. The preparation method of the polydopamine-coated nanospheres of the present invention comprises coating the nanospheres with polydopamine, and then reacting the polydopamine with sodium carboxymethylcellulose to form an amide bond. This improves the binding strength between the nanospheres and the sodium carboxymethylcellulose, and further improves the wash fastness and abrasion resistance.

Description

[0001] This application is a divisional application of the invention patent application with the application date of July 8, 2022, application number 2022108153067, and invention name “A structural chromogenic cellulose fabric and its preparation method”. Technical Field

[0002] The present invention relates to the technical field of structural color textiles, and in particular to a method for preparing polydopamine-coated nanoparticles, the nanoparticles prepared by the preparation method, and structural color-forming cellulose fabrics based on sodium carboxymethyl cellulose and the nanoparticles for improving structural color fastness. Background Art

[0003] Structural color is unrelated to pigmentation and is an optical effect caused by the submicroscopic structure of organisms. Due to its advantages such as fastness to fading, environmental friendliness, and iridescence, structural color has broad application prospects in display, decoration, and anti-counterfeiting. Currently, research on artificially creating structurally colored fabrics primarily utilizes photonic crystals. The structural color of photonic crystals self-assembled on white fabrics is often pale and low in contrast. This is due to the influence of a large amount of reflected background light from the fabric surface and incoherent scattered light from the photonic crystals.

[0004] To address this issue and enhance the contrast of structural colors, achieving vibrant and vibrant structural colors, patents CN105182567 pre-dye the fabric and then deposit photonic crystals, while patent CN111648144 introduces carbon black into the photonic crystals to achieve vibrant structural colors. However, because the nanoparticles and the substrate are primarily bound together by weak forces such as hydrogen bonds and van der Waals forces, the arrays are easily damaged by external forces (such as washing, friction, and bending), causing the structural colors to disappear. This significantly limits the application of structural colors in textiles.

[0005] Polydopamine (PDA) is the main substance of natural melanin. PDA exhibits many of the remarkable optical, electrical, and magnetic properties of natural melanin, as well as excellent biocompatibility. It also has strong adhesion similar to mussel adhesive proteins and can adhere to the surface of almost all substrates, regardless of the physical and chemical properties of the substrate surface. Therefore, the use of PDA in structural color materials can not only enhance color visibility but also improve its structural stability to meet the wearability of textiles. However, although the use of polydopamine doped / coated samples or polydopamine-coated core-shell nanoparticles can increase the adhesion between particles, because polydopamine itself is black, the amount used is limited, and the improvement in structural stability is limited, which still cannot meet the practical application needs of textiles.

[0006] Gu et al. from Southeast University (Nanoscale, 2018, 10: 3673-3679.) modified silica (SiO2) microspheres with PDA to prepare SiO2@PDA nanospheres with a core-shell structure, and further prepared SiO2@PDA amorphous photonic arrays by spraying. Then, by treating them with ammonia vapor, the PDA on the surface of the microspheres reacted with ammonia ions to form new covalent bonds, thereby increasing the interaction force between the structural elements. However, the covalent crosslinking only existed at the point contact with the nanospheres, so the improvement in fastness was limited.

[0007] Sodium carboxymethyl cellulose is a water-soluble cellulose ether derived from chemically modified natural cellulose and is the most common ionic cellulose gum. It forms a protective film on the surface of materials. It typically appears as a white, fibrous or granular powder. It is tasteless, odorless, highly hygroscopic, and insoluble in organic solvents. It is commonly used as a thickener in foods, as a binder and anti-reprecipitation agent in the daily chemical industry, and as a sizing agent and protective colloid for printing pastes in the printing and dyeing industry. To improve structural color fastness, sodium carboxymethyl cellulose can be used as a binder to bond nanoparticles. However, as a water-soluble polymer, its wash fastness needs to be addressed.

[0008] Therefore, developing a structural chromophore method with excellent optical properties and high structural stability is of great significance for promoting the practical application of structural chromophore technology in the coloring of textiles and other products.

[0009] The disclosure of the above background technology content is only used to assist in understanding the inventive concept and technical solution of the present invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above content has been disclosed before the filing date of this patent application, the above background technology should not be used to evaluate the novelty and creativity of this application. Summary of the Invention

[0010] In view of this, in order to overcome the defects of the prior art, one of the objects of the present invention is to provide a polydopamine-coated nanoparticles and a preparation method thereof, which are used to cooperate with sodium carboxymethyl cellulose to improve the binding force between the nanoparticles and sodium carboxymethyl cellulose, and further improve the water fastness and friction resistance.

[0011] The present invention also provides a structural color-forming cellulose fabric, which uses sodium carboxymethyl cellulose as an adhesive to improve the structural color fastness of the fabric.

[0012] In order to achieve the above object, the present invention adopts the following technical solutions:

[0013] A method for preparing a structural chromogenic cellulose fabric comprises the following steps:

[0014] Dispersing the polydopamine-coated nanospheres in water to obtain a nanosphere solution with a mass concentration of 20-50 wt%;

[0015] A sodium carboxymethyl cellulose aqueous solution with a mass concentration of 0.1% to 0.5% is prepared, the nanosphere solution and the sodium carboxymethyl cellulose aqueous solution are mixed and the pH is adjusted to 6.0 to 7.0, and the mixture is stirred to obtain the structural color paste;

[0016] The prepared structural color paste is applied to the surface of a cellulose fabric to a thickness of 0.1-0.5 mm. The fabric is then placed in a constant temperature and humidity environment for 1-6 hours to obtain the structural color-forming cellulose fabric. The structural color-forming cellulose fabric is then cured at 120-150°C for 30-120 minutes to obtain a structural color-forming cellulose fabric with good durability after curing. Cellulose fabric is preferably selected because it has a high hydroxyl content and can withstand a certain temperature.

[0017] According to some preferred embodiments of the present invention, the polydopamine-coated nanospheres are prepared by the following method: adding dopamine hydrochloride and an iron salt oxidation catalyst to an aqueous dispersion of the nanospheres, mixing them evenly, heating them to 30-60° C., and stirring the reaction for 5-120 minutes to obtain polydopamine-coated nanospheres.

[0018] According to some preferred embodiments of the present invention, the nanospheres are polystyrene-divinylbenzene polymer microspheres (PS-DVB microspheres).

[0019] Directly using sodium carboxymethyl cellulose to adhere polystyrene-divinylbenzene polymer microspheres to cotton fabric will, on the one hand, cause optical effects, and on the other hand, PS-DVB microspheres are hydrophobic beads, and their binding force with sodium carboxymethyl cellulose is not strong enough. Therefore, the present invention also uses polydopamine-coated nano-microspheres to simultaneously improve the refractive index of polystyrene-divinylbenzene polymer microspheres. The amino group on the polydopamine reacts with the carboxyl group of sodium carboxymethyl cellulose to form an amide bond, which improves the binding force of the nano-microspheres and sodium carboxymethyl cellulose and further improves water fastness and friction resistance. At the same time, by adjusting the particle size of the polystyrene-divinylbenzene polymer microspheres (PS-DVB microspheres), the regulation and control of the structural color hue presented thereto can be achieved. As the particle size gradually increases, the structural color-producing product prepared gradually undergoes red shift.

[0020] According to some preferred embodiments of the present invention, the volume ratio of styrene to divinylbenzene during polymerization in the polystyrene-divinylbenzene polymer microspheres is 9:1-8:2.

[0021] According to some preferred embodiments of the present invention, the aqueous dispersion of nanospheres is prepared by the following method: dispersing polystyrene-divinylbenzene polymer microspheres in water and treating them under ultrasound for 5-30 minutes to obtain an aqueous dispersion of nanospheres with a concentration of 1-10 mg / mL.

[0022] According to some preferred embodiments of the present invention, the average particle size of the nanospheres is 180-350 nm; and the monodispersity index of the nanospheres is less than 0.1.

[0023] According to some preferred embodiments of the present invention, the polydopamine-coated nanospheres are prepared by adding dopamine hydrochloride to a concentration of 0.1-1 mg / mL; and by adding the iron salt oxidation catalyst to a concentration of 0.1-1 mg / mL. Polydopamine (PDA) is the main substance of natural melanin. Although polydopamine-coated core-shell nanoparticles can increase interparticle adhesion, the amount of polydopamine used is limited due to its inherent black color, resulting in limited improvement in structural stability and still failing to meet the practical application needs of textiles.

[0024] According to some preferred embodiments of the present invention, when preparing the polydopamine-coated nanospheres, the product obtained by the reaction is washed with deionized water, dispersed under ultrasound, and then collected by centrifugation to obtain the polydopamine-coated nanospheres.

[0025] According to some preferred embodiments of the present invention, the volume ratio of the nanosphere solution to the sodium carboxymethyl cellulose aqueous solution in the structural color paste is 2:1 to 1:2.

[0026] According to some preferred embodiments of the present invention, the substance used to adjust the pH is preferably hydrochloric acid.

[0027] According to some preferred embodiments of the present invention, the iron salt oxidation catalyst is one or more selected from ferric chloride, ferric sulfate, ferric nitrate, and ferric acetate.

[0028] According to some preferred implementation aspects of the present invention, the constant temperature and humidity environment has a temperature of 30-60° C. and a humidity of 50-70%.

[0029] The present invention also provides a method for preparing the structural chromogenic cellulose fabric to prepare the structural chromogenic cellulose fabric.

[0030] Compared with the prior art, the present invention is beneficial in that: in the preparation method of the polydopamine-coated nanoparticles of the present invention, the nanoparticles are coated with polydopamine, and by combining with sodium carboxymethyl cellulose, the amino groups on the polydopamine react with the carboxyl groups of the sodium carboxymethyl cellulose to form an amide bond, thereby improving the binding force between the nanoparticles and the sodium carboxymethyl cellulose and further improving the water washing fastness and friction resistance. The structural color-forming cellulose fabric of the present invention is prepared by mixing a nano-microsphere solution with a sodium carboxymethyl cellulose aqueous solution to obtain a structural color slurry, using sodium carboxymethyl cellulose as a binder to bind the nanoparticles, thereby improving the fastness of the structural color; and adjusting the pH value to an acidic range of 6.0-7.0 so that the structural color slurry undergoes an esterification reaction under a slightly acidic condition and at 120-150° C., so that the carboxyl groups and hydroxyl groups of the sodium carboxymethyl cellulose are esterified and cross-linked, and the carboxyl groups are also cross-linked with the hydroxyl groups on the cotton fabric to form a cross-linked esterification product, thereby promoting the sodium carboxymethyl cellulose to form physical and chemical cross-links between the nano-microsphere units and between the contact surface of the sodium carboxymethyl cellulose and the cotton fabric substrate, thereby significantly enhancing the water washing fastness and friction resistance of the structural color cotton fabric. At the same time, the nano-microspheres coated with polydopamine are used so that the amino groups on the polydopamine react with the carboxyl groups of the sodium carboxymethyl cellulose to form amide bonds, thereby improving the binding force between the nano-microspheres and the sodium carboxymethyl cellulose, and further improving the water washing fastness and friction resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 is a scanning electron microscope image of the surface of the structural chromogenic cellulose fabric prepared in Example 1 of the present invention;

[0033] Figure 2 This is a microscope photograph of the structural chromogenic cellulose fabric prepared in Example 1 of the present invention after 50 bending and folding tests. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0035] The basic principle of this invention is as follows: Structural color beads have difficulty adhering directly to substrates such as cotton fabric, resulting in low structural color fastness and resistance to washing and abrasion. Sodium carboxymethylcellulose, a water-soluble cellulose ether derived from chemically modified natural cellulose, is the most common ionic cellulose glue. To improve the structural color fastness, sodium carboxymethylcellulose is used as a binder to bond the nanoparticles.

[0036] However, sodium carboxymethyl cellulose is a water-soluble polymer, and its wash fastness problem needs to be solved at the same time. In order to improve the wash fastness, the present invention adjusts the structural color slurry to a slightly acidic value of 6 to 7, and at the same time adds a high-temperature color fixing process when preparing the fabric. Under the condition of controlling the slightly acidic state, the sodium carboxymethyl cellulose is heated at 120°C-150°C for a period of time, and an esterification reaction occurs, so that the carboxyl groups of the sodium carboxymethyl cellulose itself are esterified and cross-linked with the hydroxyl groups on the cotton fabric. In addition, the carboxyl groups are also cross-linked with the hydroxyl groups on the cotton fabric, and finally a cross-linked esterification product is formed. This promotes the formation of physical and chemical cross-links between the sodium carboxymethyl cellulose nanosphere elements and between the contact surfaces of the sodium carboxymethyl cellulose and the cotton fabric substrate, significantly enhancing the wash fastness and friction resistance of the structural color product.

[0037] In addition, directly using sodium carboxymethylcellulose to adhere polystyrene-divinylbenzene polymer microspheres to cotton fabric will, on the one hand, cause optical effects, and on the other hand, the PS-DVB microspheres are hydrophobic beads, and their binding force with sodium carboxymethylcellulose is not strong enough. Therefore, the present invention also uses polydopamine to coat nano-microspheres to improve the refractive index of polystyrene-divinylbenzene polymer microspheres. The amino group on the polydopamine reacts with the carboxyl group of sodium carboxymethylcellulose to form an amide bond, which improves the binding force between the nano-microspheres and sodium carboxymethylcellulose and further improves the fastness to washing and the friction resistance. At the same time, by adjusting the particle size of the polystyrene-polydivinylbenzene cross-linked nano-microspheres, the structural color hue presented can be regulated and controlled. As the particle size gradually increases, the structural color-producing product prepared gradually undergoes red shift.

[0038] Based on the above principles, the preparation method of the present invention for improving the color fastness of cotton fabric structure based on sodium carboxymethyl cellulose specifically comprises the following steps:

[0039] (1) Dispersion of nanospheres

[0040] An aqueous dispersion of polystyrene-divinylbenzene polymer microspheres at a concentration of 1-10 mg / mL is prepared and ultrasonicated for 5-30 minutes to achieve full dispersion. The volume ratio of styrene to divinylbenzene during polymerization is 9:1-8:2. The nanospheres have an average particle size of 180-350 nm, good sphericity, and a monodispersity index of less than 0.1, enabling control of structural color hue.

[0041] (2) Surface coating of nanospheres

[0042] Dopamine hydrochloride is added to the aqueous dispersion of polystyrene-divinylbenzene polymer microspheres prepared in step (1) to a concentration of 0.1-1 mg / mL, and an iron salt oxidation catalyst is added to a concentration of 0.1-1 mg / mL. The temperature is then raised to 30-60°C and stirred for a reaction of 5-120 minutes to promote oxidative polymerization of dopamine and encapsulation of the nanospheres. After the reaction, the product is washed with deionized water, ultrasonically dispersed, and collected by centrifugation to obtain polydopamine-coated nanospheres.

[0043] The iron salt oxidation catalyst is one or more selected from ferric chloride, ferric sulfate, ferric nitrate, and ferric acetate.

[0044] (3) Configuration of structural color paste

[0045] The polydopamine-coated nanospheres prepared in step (2) are dispersed in deionized water at a mass concentration of 20-50 wt%, and dispersed by ultrasonication for 5-30 min to obtain a nanosphere solution.

[0046] Prepare a sodium carboxymethyl cellulose aqueous solution with a mass concentration of 0.1% to 0.5%.

[0047] The nanosphere solution is mixed with the sodium carboxymethyl cellulose aqueous solution, hydrochloric acid is added to adjust the pH to 6.0-7.0, and the mixture is stirred evenly to obtain a structural color slurry.

[0048] The volume ratio of the nanosphere solution to the sodium carboxymethyl cellulose aqueous solution in the structural color paste is 2:1 to 1:2.

[0049] (4) Preparation of structural color cotton fabrics

[0050] The structural color slurry prepared in step (3) is uniformly cast onto the surface of the cotton fabric with a thickness of 0.1-0.5 mm, and then assembled in a constant temperature and humidity environment for 1-6 hours to obtain a structural color-forming cellulose fabric.

[0051] The assembly conditions in a constant temperature and humidity environment are a temperature of 30-60°C and a humidity of 50-70%.

[0052] (5) Curing of structural color cotton fabrics

[0053] The structural chromogenic cellulose fabric obtained in step (4) is placed in a drying room and treated at 120-150° C. for 30-120 minutes to obtain a structural chromogenic cellulose fabric with good durability.

[0054] Example 1

[0055] The preparation method of the structural color cotton fabric in this embodiment comprises the following steps:

[0056] (1) Dispersion of nanospheres

[0057] Polystyrene-divinylbenzene polymer microspheres with a particle size of 215 nm, a monodispersity index of 0.06, and a cross-linking ratio of 8:2 were selected, prepared into a 5 mg / mL aqueous dispersion, and ultrasonically treated for 15 minutes to fully disperse them.

[0058] (2) Surface coating of nanospheres

[0059] Dopamine hydrochloride was added to the aqueous dispersion of polystyrene-divinylbenzene polymer microspheres prepared in step (1) to a concentration of 0.3 mg / mL. Ferric chloride oxidation catalyst was also added to a concentration of 0.3 mg / mL. The temperature was then raised to 40°C and stirred for 60 minutes to promote oxidative polymerization of dopamine and encapsulation of the nanospheres. After the reaction, the product was washed with deionized water, ultrasonically dispersed, and collected by centrifugation to obtain polydopa-coated nanospheres.

[0060] (3) Configuration of structural color paste

[0061] The surface-coated nanospheres obtained in step (2) were dispersed in deionized water at a mass concentration of 35 wt %, and dispersed by ultrasonication for 20 min to obtain a nanosphere solution.

[0062] Prepare a sodium carboxymethyl cellulose aqueous solution with a mass concentration of 0.4%.

[0063] The nanosphere solution and the sodium carboxymethyl cellulose aqueous solution were mixed at a volume ratio of 2:1, hydrochloric acid was added to adjust the pH to 6.5, and the mixture was stirred evenly to obtain a structural color slurry.

[0064] (4) Preparation of structural color cotton fabrics

[0065] The structural color slurry prepared in step (3) was uniformly cast onto the surface of the cotton fabric with a thickness of 0.4 mm, and then assembled in an environment of temperature 30° C. and humidity 50% for 4 hours to obtain a structural color-forming cellulose fabric.

[0066] (5) Self-esterification curing of structural color cotton fabrics

[0067] The structural chromogenic cellulose fabric obtained in step (4) is placed in a drying room and treated at 140° C. for 60 minutes to obtain a durable green structural chromogenic cellulose fabric.

[0068] Example 2

[0069] The preparation method of the structural color cotton fabric in this embodiment comprises the following steps:

[0070] (1) Dispersion of nanospheres

[0071] Polystyrene-divinylbenzene polymer microspheres with a particle size of 181 nm, a monodispersity index of 0.04, and a cross-linking ratio of 8.5:1.5 were selected, prepared into a 6 mg / mL aqueous dispersion, and ultrasonically treated for 20 minutes to fully disperse.

[0072] (2) Surface coating of nanospheres

[0073] Dopamine hydrochloride was added to the aqueous dispersion of polystyrene-divinylbenzene polymer microspheres prepared in step (1) to a concentration of 0.4 mg / mL. Ferric sulfate oxidation catalyst was also added to a concentration of 0.4 mg / mL. The temperature was then raised to 45°C and stirred for 50 minutes to promote oxidative polymerization of dopamine and encapsulation of the nanospheres. After the reaction, the product was washed with deionized water, ultrasonically dispersed, and collected by centrifugation to obtain polydopamine-coated nanospheres.

[0074] (3) Configuration of structural color paste

[0075] The surface-coated nanospheres obtained in step (2) were dispersed in deionized water at a mass concentration of 30 wt%, and dispersed by ultrasonication for 20 min to obtain a nanosphere solution.

[0076] Prepare sodium carboxymethyl cellulose aqueous solution with a mass concentration of 0.5%.

[0077] The nanosphere solution and the sodium carboxymethyl cellulose aqueous solution were mixed at a volume ratio of 1.5:1, hydrochloric acid was added to adjust the pH to 6.4, and the mixture was stirred evenly to obtain a structural color slurry.

[0078] (4) Preparation of structural color cotton fabrics

[0079] The structural color slurry prepared in step (3) was uniformly cast onto the surface of the cotton fabric with a thickness of 0.4 mm, and then assembled in an environment of temperature 30° C. and humidity 70% for 5 hours to obtain a structural color-forming cellulose fabric.

[0080] (5) Self-esterification curing of structural color cotton fabrics

[0081] The structural chromogenic cellulose fabric obtained in step (4) is placed in a drying room and treated at 145° C. for 40 minutes to obtain a blue structural chromogenic cellulose fabric with good durability.

[0082] Example 3

[0083] The preparation method of the structural color cotton fabric in this embodiment comprises the following steps:

[0084] (1) Dispersion of nanospheres

[0085] Polystyrene-divinylbenzene polymer microspheres with a particle size of 243 nm, a monodispersity index of 0.03, and a crosslinking ratio of 9:1 were prepared into a 2 mg / mL aqueous dispersion of polystyrene-divinylbenzene polymer microspheres and ultrasonicated for 15 min to fully disperse them.

[0086] (2) Surface coating of nanospheres

[0087] Dopamine hydrochloride was added to the aqueous dispersion of polystyrene-divinylbenzene polymer microspheres prepared in step (1) to a concentration of 0.5 mg / mL, and ferric nitrate oxidation catalyst was added to a concentration of 0.4 mg / mL. The temperature was then raised to 35°C and stirred for 70 minutes to promote oxidative polymerization of dopamine and encapsulation of the nanospheres. After the reaction, the product was washed with deionized water, ultrasonically dispersed, and collected by centrifugation to obtain polydopamine-coated nanospheres.

[0088] (3) Configuration of structural color paste

[0089] The surface-coated nanospheres obtained in step (2) were dispersed in deionized water at a mass concentration of 45 wt%, and dispersed by ultrasonication for 25 min to obtain a nanosphere solution.

[0090] Prepare a sodium carboxymethyl cellulose aqueous solution with a mass concentration of 0.2%.

[0091] The nanosphere solution and the sodium carboxymethyl cellulose aqueous solution were mixed in a volume ratio of 1:2, hydrochloric acid was added to adjust the pH to 6.2, and the mixture was stirred evenly to obtain a structural color slurry.

[0092] (4) Preparation of structural color cotton fabrics

[0093] The structural color slurry prepared in step (3) was uniformly cast onto the surface of the cotton fabric with a thickness of 0.3 mm, and then assembled in an environment of temperature 25° C. and humidity 60% for 6 hours to obtain a structural color-forming cellulose fabric.

[0094] (5) Self-esterification curing of structural color cotton fabrics

[0095] The structural chromogenic cellulose fabric obtained in step (4) is placed in a drying room and treated at 130° C. for 100 minutes to obtain a red structural chromogenic cellulose fabric with good durability.

[0096] Example 4

[0097] The preparation method of the structural color cotton fabric in this embodiment comprises the following steps:

[0098] (1) Dispersion of nanospheres

[0099] Polystyrene-polydivinylbenzene cross-linked (PS-DVB) nanospheres with a particle size of 215 nm, a monodispersity index of 0.06, and a cross-linking ratio of 8:2 were selected, and a 4 mg / mL aqueous dispersion was prepared and fully dispersed by ultrasonic treatment for 15 minutes.

[0100] (2) Surface coating of nanospheres

[0101] Dopamine hydrochloride was added to the aqueous dispersion of polystyrene-divinylbenzene polymer microspheres prepared in step (1) to a concentration of 0.6 mg / mL. Ferric acetate oxidation catalyst was also added to a concentration of 0.6 mg / mL. The temperature was then raised to 50°C and stirred for 15 minutes to promote oxidative polymerization of dopamine and encapsulation of the nanospheres. After the reaction, the product was washed with deionized water, ultrasonically dispersed, and collected by centrifugation to obtain polydopamine-coated nanospheres.

[0102] (3) Configuration of structural color paste

[0103] The surface-coated nanospheres obtained in step (2) were dispersed in deionized water at a mass concentration of 35 wt %, and dispersed by ultrasonication for 20 min to obtain a nanosphere solution.

[0104] Prepare a sodium carboxymethyl cellulose aqueous solution with a mass concentration of 0.4%.

[0105] The nanosphere solution and the sodium carboxymethyl cellulose aqueous solution were mixed in a volume ratio of 1:1, hydrochloric acid was added to adjust the pH to 6.7, and the mixture was stirred evenly to obtain a structural color slurry.

[0106] (4) Preparation of structural color cotton fabrics

[0107] The structural color slurry prepared in step (3) was uniformly cast onto the surface of the cotton fabric with a thickness of 0.3 mm, and then assembled in an environment of a temperature of 50° C. and a humidity of 70% for 2 hours to obtain a structural color-forming cellulose fabric.

[0108] (5) Self-esterification curing of structural color cotton fabrics

[0109] The structural chromogenic cellulose fabric obtained in step (4) is placed in a drying room and treated at 120° C. for 120 minutes to obtain a durable green structural chromogenic cellulose fabric.

[0110] Example 5

[0111] The preparation method of the structural color cotton fabric in this embodiment comprises the following steps:

[0112] (1) Dispersion of nanospheres

[0113] Polystyrene-divinylbenzene polymer microspheres with a particle size of 181 nm, a monodispersity index of 0.04, and a cross-linking ratio of 8.5:1.5 were selected, prepared into a 7 mg / mL aqueous dispersion, and ultrasonically treated for 25 minutes to fully disperse.

[0114] (2) Surface coating of nanospheres

[0115] Dopamine hydrochloride was added to the aqueous dispersion of polystyrene-divinylbenzene polymer microspheres prepared in step (1) to a concentration of 0.6 mg / mL. Ferric chloride oxidation catalyst was also added to a concentration of 0.6 mg / mL. The temperature was then raised to 50°C and stirred for 15 minutes to promote oxidative polymerization of dopamine and encapsulation of the nanospheres. After the reaction, the product was washed with deionized water, ultrasonically dispersed, and collected by centrifugation to obtain polydopamine-coated nanospheres.

[0116] (3) Configuration of structural color paste

[0117] The surface-coated nanospheres obtained in step (2) were dispersed in deionized water at a mass concentration of 30 wt%, and dispersed by ultrasonication for 16 min to obtain a nanosphere solution.

[0118] Prepare a sodium carboxymethyl cellulose aqueous solution with a mass concentration of 0.2%.

[0119] The nanosphere solution and the sodium carboxymethyl cellulose aqueous solution were mixed in a volume ratio of 1:1, hydrochloric acid was added to adjust the pH to 6.5, and the mixture was stirred evenly to obtain a structural color slurry.

[0120] (4) Preparation of structural color cotton fabrics

[0121] The structural color slurry prepared in step (3) was uniformly cast onto the surface of the cotton fabric with a thickness of 0.3 mm, and then assembled in an environment of temperature 30° C. and humidity 60% for 4 hours to obtain a structural color-forming cellulose fabric.

[0122] (5) Self-esterification curing of structural color cotton fabrics

[0123] The structural chromogenic cellulose fabric obtained in step (4) is placed in a drying room and treated at 135° C. for 90 minutes to obtain a blue structural chromogenic cellulose fabric with good durability.

[0124] Example 6

[0125] The preparation method of the structural color cotton fabric in this embodiment comprises the following steps:

[0126] (1) Dispersion of nanospheres

[0127] Polystyrene-divinylbenzene polymer microspheres with a particle size of 243 nm, a monodispersity index of 0.03, and a cross-linking ratio of 9:1 were selected, prepared into a 5 mg / mL aqueous dispersion, and ultrasonically treated for 20 minutes to fully disperse.

[0128] (2) Surface coating of nanospheres

[0129] Dopamine hydrochloride was added to the aqueous dispersion of polystyrene-divinylbenzene polymer microspheres prepared in step (1) to a concentration of 0.4 mg / mL, and an oxidizing catalyst of ferric sulfate was added to a concentration of 0.5 mg / mL. The temperature was then raised to 40°C and stirred for 20 minutes to promote oxidative polymerization of dopamine and encapsulation of the nanospheres. After the reaction, the product was washed with deionized water, ultrasonically dispersed, and collected by centrifugation to obtain polydopamine-coated nanospheres.

[0130] (3) Configuration of structural color paste

[0131] The surface-coated nanospheres obtained in step (2) were dispersed in deionized water at a mass concentration of 25 wt %, and dispersed by ultrasonication for 16 min to obtain a nanosphere solution.

[0132] Prepare a sodium carboxymethyl cellulose aqueous solution with a mass concentration of 0.3%.

[0133] The nanosphere solution and the sodium carboxymethyl cellulose aqueous solution were mixed in a volume ratio of 1:1, hydrochloric acid was added to adjust the pH to 6.5, and the mixture was stirred evenly to obtain a structural color slurry.

[0134] (4) Preparation of structural color cotton fabrics

[0135] The structural color slurry prepared in step (3) was uniformly cast onto the surface of the cotton fabric with a thickness of 0.4 mm, and then assembled in an environment of temperature 30° C. and humidity 50% for 6 hours to obtain a structural color-forming cellulose fabric.

[0136] (5) Self-esterification curing of structural color cotton fabrics

[0137] The structural chromogenic cellulose fabric obtained in step (4) is placed in a drying room and treated at 130° C. for 110 minutes to obtain a blue structural chromogenic cellulose fabric with good durability.

[0138] Comparative Example 1

[0139] The difference between this comparative example and Example 1 is that this comparative example eliminates step 5 in Example 1, that is, this comparative example does not include the step of high-temperature curing of the structural chromogenic cellulose fabric.

[0140] Comparative Example 2

[0141] The difference between this comparative example and Example 1 is that the nanospheres in the structural color paste in this comparative example are directly unmodified polystyrene-divinylbenzene polymer microspheres, rather than the polydopamine-coated nanospheres in the example.

[0142] Comparative Example 3

[0143] The difference between this comparative example and Example 1 is that in this comparative example, the high-temperature curing condition in step 5 of Example 1 is lowered, that is, the curing condition adopted in this comparative example is curing treatment at 100° C. for 30 minutes.

[0144] Results and Tests

[0145] 1) Scanning electron microscopy image of the surface of structural chromogenic cellulose fabric

[0146] Figure 1 This is a scanning electron microscope image of the surface of the structural chromogenic cellulose fabric prepared in Example 1.

[0147] from Figure 1 It can be seen that the nanospheres are encapsulated on the surface of textiles by sodium carboxymethyl cellulose, and the nanoparticles have a long-range disordered and short-range ordered arrangement structure.

[0148] 2) Bending and folding test of structural chromogenic cellulose fabric

[0149] Figure 2 This is the result of 50 bending and folding tests on the structural chromogenic cellulose fabric prepared in Example 1.

[0150] The bending and folding test involved folding and bending one end of the resulting textile horizontally until it touched the other end. An optical microscope was used to observe the changes in the surface structural color of the textile after folding and bending. The images show that the prepared structurally colored cellulose fabric is structurally stable and fold-resistant.

[0151] 3) Soap-washing color fastness and bending and folding test

[0152] Table 1 shows the results of color fastness to washing and bending and folding tests for the structurally colored cellulose fabrics prepared in Examples 1-6. Color fastness to washing was measured in accordance with GB / T 3921-2008, "Textiles - Tests for Color Fastness - Color Fastness to Washing." The bending and folding test involved folding and bending one end of the resulting textile horizontally until it touched the other end. A scanning electron microscope and a digital camera were used to observe the changes in the structural color and amorphous photonic array on the surface of the structurally colored textile before and after folding and bending.

[0153] Table 1 Washing fastness and bending and folding test results of the structural chromogenic cellulose fabric in the embodiment

[0154]

[0155] The fading values ​​in Table 1 represent wash fastness, rated on a scale of 1-5, with 1 being the lowest and 5 being the highest. The data in Table 1 demonstrate that the structured chromogenic cellulose fabrics prepared in Examples exhibit excellent color fastness and structural stability. However, the uncured fabric in Comparative Example 1 exhibited severe fading, with numerous polyvinyl divinylbenzene particles being washed out of the soaping solution. Furthermore, the curing temperature in Comparative Example 3 was low, resulting in poor wash fastness.

[0156] PS-DVB nanospheres are originally colorless and develop color after forming a certain nano-stacked structure. However, the particles are very easy to fall off, so a curing method with a stronger color development effect is required. The present invention discloses a method for improving the structural color fastness of cotton fabrics based on sodium carboxymethyl cellulose. The key lies in the use of the fixing effect of sodium carboxymethyl cellulose, which can firmly adhere to cellulose. The technical solution of the present invention is as follows: a sodium carboxymethyl cellulose solution with a certain solid content and a dispersion of dopamine-coated high-refractive index core-shell nanospheres are mixed uniformly in a certain volume ratio and then applied to cotton fabric. The cotton fabric is then placed in a drying device for drying and curing. After the liquid is completely evaporated, a soft, bright, and color-fast structural color-forming cellulose fabric is obtained. The bonding strength between the structural elements and between the structural elements and the substrate is enhanced, the structure is stable, and the color durability is improved. The method of the present invention is simple to operate, low in cost, and has mild reaction conditions. It does not involve any organic solvents or polymer functional monomers. In addition, both dopamine and sodium carboxymethyl cellulose are natural products and are environmentally friendly. This method effectively solves the defects of the existing technology that the structural color is easy to fall off and unstable, can ensure the durability of the structural color of cotton fabrics, and has the advantages of being easy to implement, low cost, green and environmentally friendly, and having good universality.

[0157] The equipment and raw materials used in the above-mentioned embodiments can be purchased from the market or are commonly used in this area. The methods in the above-mentioned embodiments, unless otherwise specified, are conventional methods in this area. The raw materials not specifically specified in the embodiments are all commercially available. Operations without special mention of temperature are carried out at room temperature. The operating methods and conditions not specifically specified can adopt the well-known or conventional means and conditions in this area. The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed in this article.

[0158] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable people familiar with this technology to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A structural chromogenic cellulose fabric, characterized in that: Prepared by the following method: Dispersing the polydopamine-coated nanospheres in water to obtain a nanosphere solution with a mass concentration of 20-50 wt%; A sodium carboxymethyl cellulose aqueous solution with a mass concentration of 0.1% to 0.5% is prepared, the nanosphere solution and the sodium carboxymethyl cellulose aqueous solution are mixed and the pH is adjusted to 6.0 to 7.0, and the mixture is stirred to obtain a structural color paste; Covering the prepared structural color slurry on the surface of cellulose fabric; placing the fabric under a constant temperature and humidity environment for 1-6 hours to obtain the structural chromogenic cellulose fabric; curing the structural chromogenic cellulose fabric at 120-150° C. for 40-120 minutes to obtain a structural chromogenic cellulose fabric having good durability after curing; The polydopamine-coated nanospheres are prepared by the following method: Dopamine hydrochloride and an iron salt oxidation catalyst are added to the aqueous dispersion of nanospheres, mixed evenly, and then heated to 30-60° C. and stirred for reaction for 5-120 minutes to obtain polydopamine-coated nanospheres; the nanospheres are polystyrene-divinylbenzene polymer microspheres.

2. The structural chromogenic cellulose fabric according to claim 1, characterized in that The volume ratio of styrene to divinylbenzene in the polystyrene-divinylbenzene polymer microspheres during polymerization is 9:1-8:

2.

3. The structural chromogenic cellulose fabric according to claim 1, characterized in that The average particle size of the nanospheres is 180-350 nm.

4. The structural chromogenic cellulose fabric according to claim 1, characterized in that The monodispersity index of the nanospheres is less than 0.

1.

5. The structural chromogenic cellulose fabric according to claim 1, characterized in that When dopamine hydrochloride is added, the concentration of dopamine hydrochloride in the system is 0.1-1 mg / mL.

6. The structural chromogenic cellulose fabric according to claim 1, characterized in that When the iron salt oxidation catalyst is added, the concentration of the iron salt oxidation catalyst in the system is 0.1-1 mg / mL.

7. The structural chromogenic cellulose fabric according to claim 1, characterized in that The iron salt oxidation catalyst is one or more selected from ferric chloride, ferric sulfate, ferric nitrate, and ferric acetate.

8. The structural chromogenic cellulose fabric according to claim 1, characterized in that When preparing the polydopamine-coated nanoparticles, the product obtained by the reaction is washed with deionized water, dispersed under ultrasound, and then collected by centrifugation to obtain the polydopamine-coated nanoparticles.

9. The structural chromogenic cellulose fabric according to claim 1, wherein The aqueous dispersion of nanospheres is prepared by the following method: dispersing polystyrene-divinylbenzene polymer microspheres in water, and treating the water under ultrasound for 5-30 minutes to obtain an aqueous dispersion of nanospheres with a concentration of 1-10 mg / mL.

10. The structural chromogenic cellulose fabric according to claim 1, characterized in that The volume ratio of the nanosphere solution to the sodium carboxymethyl cellulose aqueous solution in the structural color paste is 2:1 to 1:

2.

11. The structural chromogenic cellulose fabric according to claim 1, characterized in that The thickness of the structural color slurry when covering the surface of the cellulose fabric is 0.1-0.5 mm.

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