A recyclable 3D printing thermo-sensitive cellulose photonic ink and a preparation method thereof

Abstract

This invention discloses a recyclable 3D printing thermosensitive cellulose photonic ink and its preparation method, belonging to the field of functional polymer materials. The preparation method includes the following steps: adding both an alcohol solvent and a supramolecular solvent to an aqueous solution to obtain a mixed aqueous solution; dissolving hydroxypropyl cellulose in this mixed aqueous solution, which self-assembles to form a cholesteric liquid crystal structure exhibiting a bright structural color, thus preparing the thermosensitive cellulose photonic ink. This thermosensitive cellulose photonic ink can be used for 3D printing, and the resulting pattern displays different colors depending on the temperature. The structural color of the thermosensitive cellulose photonic ink of this invention originates from the self-assembly behavior of hydroxypropyl cellulose in the mixed aqueous solution, and hydroxypropyl cellulose is renewable and biocompatible, resulting in a photonic ink that is recyclable and reprintable.

Description

Technical Field

[0001] This invention belongs to the field of functional polymer materials and relates to a recyclable 3D printing temperature-sensitive cellulose photonic ink and its preparation method. Background Technology

[0002] In recent years, 3D printing technology has demonstrated enormous application potential in the preparation of smart responsive materials, particularly in fields such as sensing and anti-counterfeiting, information encryption, and optical displays, enabling the design and functional integration of complex structures. However, current photonic materials suitable for 3D printing still face numerous challenges in practical applications. On the one hand, traditional structural color materials often rely on chemical dyes or static photonic crystals, making dynamic color control difficult. On the other hand, existing materials are often difficult to recycle and reuse after printing, leading to resource waste and environmental burden. Furthermore, how to improve the material's response speed, mechanical strength, and cycle stability while ensuring optical performance remains a key challenge restricting its commercial application.

[0003] Structural color materials, due to their advantages such as no need for dyes, environmental friendliness, and stable optical properties, have gradually become a research hotspot in the fields of smart displays and anti-counterfeiting. Among them, photonic ink, as a printable structural color material, can form periodic nanostructures through self-assembly, achieving light control and exhibiting bright structural colors. However, existing photonic inks are mostly based on rigid polymer or hydrogel systems, which suffer from slow response speed, poor printability, and difficulty in constructing three-dimensional structures, making it difficult to meet the needs of fabricating high-precision, complex optical devices. Therefore, developing a photonic ink that combines excellent optical properties, temperature response characteristics, and printability has significant research value and application prospects.

[0004] To address the aforementioned issues, this invention proposes a recyclable 3D printing temperature-sensitive cellulose photonic ink and its preparation method. This material utilizes the self-assembly behavior of hydroxypropyl cellulose in aqueous solution to form a cholesteric liquid crystal structure, endowing the ink with bright structural color and reversible temperature response characteristics. Simultaneously, by introducing a supramolecular solvent, intermolecular interactions are enhanced, giving the ink excellent rheological properties and recyclability. It is not only suitable for high-precision 3D printing but also allows for multiple reuses. Compared to traditional photonic materials, the temperature-sensitive cellulose photonic ink prepared in this invention offers advantages such as being environmentally friendly, reprintable, having a rapid response, and adjustable structural color, providing a new solution for intelligent sensing, information encryption, and recyclable optical devices. Summary of the Invention

[0005] The purpose of this invention is to address the problems in the prior art by proposing a method for preparing recyclable 3D printing temperature-sensitive cellulose photonic ink. This method utilizes the self-assembly behavior of hydroxypropyl cellulose in aqueous solution to form a cholesteric liquid crystal structure, imparting a temperature-dependent structural color to the ink. Furthermore, the prepared photonic ink possesses recyclable and reprintable characteristics. To achieve the above objective, this invention adopts the following technical solution: a method for preparing recyclable 3D printing temperature-sensitive cellulose photonic ink, comprising the following steps: S1. Both the alcohol solvent and the supramolecular solvent are added to the aqueous solution, and a homogeneous mixed aqueous solution is obtained by stirring. The amount of alcohol solvent added is 1 wt% to 5 wt%, and the amount of supramolecular solvent added is 0 wt% to 2 wt%, based on the mass of water. S2. Add hydroxypropyl cellulose powder to the mixed aqueous solution and stir quickly to dissolve; then place the hydroxypropyl cellulose mixed solution in a centrifuge to remove air bubbles, and self-assemble photonic crystals at 20~30℃ until a uniform structural color appears, to obtain the recyclable 3D printing thermosensitive cellulose photonic ink; Based on the total mass of the final photonic ink, the mass fraction of hydroxypropyl cellulose is 60wt%~80wt%. A further technical solution is that the alcohol solvent in step S1 is one or more of methanol, ethanol, ethylene glycol, and propylene glycol.

[0006] Furthermore, the alcohol solvent has a water mass fraction of 1wt% to 5wt%.

[0007] Furthermore, the supramolecular solvent is one or more of polyethyleneimine, poly(2-dimethylaminoethyl methacrylate), and polyamide.

[0008] Furthermore, the supramolecular solvent has a water mass fraction of 0wt% to 2wt%.

[0009] A further technical solution is that, in step S2, the viscosity of the added hydroxypropyl cellulose is one or more of the following: 2.0~2.9 mPa•s, 3.0~6 mPa•s, 6.0~10.0 mPa•s, and 150~400 mPa•s; the centrifuge speed is 3000~5000 rpm; and the time is 3~5 min.

[0010] Furthermore, the mass fraction of added hydroxypropyl cellulose is 60 wt% to 80 wt%.

[0011] Furthermore, the self-assembly time of the recyclable 3D printing temperature-sensitive cellulose photonic ink is 2-4 weeks.

[0012] A recyclable 3D printing thermosensitive cellulose photonic ink prepared by the above preparation method.

[0013] The advantages and beneficial effects of this invention are as follows: (1) The recyclable 3D printing thermosensitive cellulose photonic ink prepared by the present invention is based on the self-assembly behavior of hydroxypropyl cellulose in aqueous solution. The reversible change of structural color is achieved by controlling the temperature, thereby constructing thermosensitive cellulose photonic ink. The thermosensitive cellulose photonic ink can be 3D printed to obtain a pattern with a specified color. The pattern can display different colors with temperature changes. No other additional equipment is required. It can be directly observed and is easy to operate. (2) The raw materials used in the preparation and application of this invention are green and environmentally friendly. The materials themselves are non-toxic, harmless, and biodegradable. This preparation method utilizes the reversibility and dynamism formed by the interaction between supramolecular and hydroxypropyl cellulose to design a recyclable photonic ink, so that the prepared photonic ink has the characteristics of being recyclable and reprintable. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the preparation process of the present invention; Figure 2 A digital photograph of the photonic ink prepared according to the present invention; Figure 3 (a) is a scanning electron microscope image of the photonic ink prepared in this invention. Figure 3 (b) is a polarizing microscope image; Figure 4 The temperature response reflectance spectrum of the photonic ink prepared according to this invention is shown. Figure 5 The shear viscosity curve of the photonic ink prepared in this invention is shown. Figure 6 This is a continuous step strain scanning curve of the photonic ink prepared according to the present invention; Figure 7 The pattern obtained by 3D printing using the photonic ink prepared in this invention; Figure 8 (a) is a pattern obtained by direct 3D printing using the photonic ink prepared in this invention. Figure 8 (b) is the pattern obtained by reprinting after recycling. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0016] Example 1: As Figure 1As shown, the method for preparing a recyclable 3D printing temperature-sensitive cellulose photonic ink according to the present invention is as follows: Step 1: Add both ethanol solvent and polyethyleneimine to 10g of aqueous solution and stir to obtain a homogeneous mixed aqueous solution; Based on the mass of water, the amount of ethanol solvent added was 4 wt%; the amount of polyethyleneimine added was 0 wt%. Step 2: Add hydroxypropyl cellulose powder to the mixed aqueous solution and stir quickly to dissolve; then place the hydroxypropyl cellulose mixture in a centrifuge to remove air bubbles, and self-assemble photonic crystals at 20~30℃ until a uniform structural color appears, to obtain the recyclable 3D printing thermosensitive cellulose photonic ink; The viscosity of hydroxypropyl cellulose is 2.9 mPa•s, and its mass fraction is 68 wt% based on the total mass of the final photonic ink; the centrifuge speed is 4500 rpm and the time is 5 min; the assembly time is 4 weeks.

[0017] Example 2: A method for preparing a recyclable 3D printing temperature-sensitive cellulose photonic ink, which is prepared through the following steps: Step 1: Add both ethanol solvent and polyethyleneimine to 10g of aqueous solution and stir to obtain a homogeneous mixed aqueous solution; Based on the mass of water, the amount of ethanol solvent added was 4 wt%; the amount of polyethyleneimine added was 0.5 wt%. Step 2: Add hydroxypropyl cellulose powder to the mixed aqueous solution and stir quickly to dissolve; then place the hydroxypropyl cellulose mixture in a centrifuge to remove air bubbles, and self-assemble photonic crystals at 20~30℃ until a uniform structural color appears, to obtain the recyclable 3D printing thermosensitive cellulose photonic ink; The viscosity of hydroxypropyl cellulose is 2.9 mPa•s, and its mass fraction is 68 wt% based on the total mass of the final photonic ink; the centrifuge speed is 4500 rpm and the time is 5 min; the assembly time is 4 weeks.

[0018] Example 3: A method for preparing a recyclable 3D printing temperature-sensitive cellulose photonic ink, which is prepared through the following steps: Step 1: Add both ethanol solvent and polyethyleneimine to 10g of aqueous solution and stir to obtain a homogeneous mixed aqueous solution; Based on the mass of water, the amount of ethanol solvent added was 4 wt%; the amount of polyethyleneimine added was 1 wt%. Step 2: Add hydroxypropyl cellulose powder to the mixed aqueous solution and stir quickly to dissolve; then place the hydroxypropyl cellulose mixture in a centrifuge to remove air bubbles, and self-assemble photonic crystals at 20~30℃ until a uniform structural color appears, to obtain the recyclable 3D printing thermosensitive cellulose photonic ink; The viscosity of hydroxypropyl cellulose is 2.9 mPa•s, and its mass fraction is 68 wt% based on the total mass of the final photonic ink; the centrifuge speed is 4500 rpm and the time is 5 min; the assembly time is 4 weeks.

[0019] A schematic diagram of the specific preparation process is shown below. Figure 1 As shown.

[0020] The colors of the photonic inks prepared in steps 1, 2, and 3 of Examples 1 to 4 were observed, and the results are as follows: Figure 2 As shown; Figure 2 It was revealed that the photonic ink exhibits a bright and uniform structural color under natural light, and that the color of the photonic ink undergoes a blue shift as the content of supramolecular solvent increases.

[0021] The photonic ink prepared in Example 3 was subjected to scanning electron microscopy and polarizing microscopy tests, and the results are as follows: Figure 3 As shown in (a) and 3(b); Figure 3 (a) reveals that the prepared photonic ink exhibits a periodic layered structure of cholesteric liquid crystal. Figure 3 (b) shows a clear birefringence phenomenon.

[0022] The photonic ink prepared in Example 3 was subjected to optical performance testing, and the results are as follows: Figure 4 As shown; Figure 4 The study revealed that when the reflectance spectrum of the photonic ink was tested, the position of the reflectance peak gradually shifted from blue to red as the temperature increased from 5℃ to 30℃, indicating that the photonic ink has good temperature response performance.

[0023] The photonic inks prepared in Examples 1, 2, 3, and 4 were subjected to shear viscosity tests, and the results are as follows: Figure 5 As shown; Figure 5 The photonic inks of Examples 1, 2, 3 and 4 were shown to exhibit typical shear-thinning behavior, with viscosity gradually decreasing as the shear rate increased, indicating that they have good rheological properties.

[0024] The photonic ink prepared in Example 3 was subjected to continuous step strain scanning tests, and the results are as follows: Figure 6 As shown; Figure 6 It was revealed that the photonic ink prepared in Example 3 exhibits excellent recovery performance, with its viscosity responding rapidly and reversibly under alternating low and high shear rates, and the printed structure can be stabilized quickly.

[0025] The photonic ink prepared in Example 3 was used for 3D printing to produce patterned labels, and the results are as follows: Figure 7 As shown; Figure 7 It was revealed that the photonic ink prepared in Example 3 can be used to 3D print snowflake-patterned labels, which exhibit obvious color changes at different temperatures.

[0026] The patterns directly 3D printed from the photonic ink prepared in Example 3 and the patterns that were recycled and reprinted are shown in the following figures. Figure 8 As shown in (a) and 8(b); Figure 8 (a) The pattern formed by 3D printing of the photonic ink prepared in Example 3 is shown to be bright in color and clear in structure, indicating that the ink has good printing performance and optical performance. Figure 8 (b) It reveals that after the photonic ink has been recycled, the pattern structure obtained by 3D printing is well maintained and the color is uniform, which proves that the photonic ink has excellent recyclable and reprintable properties.

[0027] Example 4: A method for preparing a recyclable 3D printing temperature-sensitive cellulose photonic ink, which is prepared through the following steps: Step 1: Add both ethanol solvent and polyethyleneimine to 10g of aqueous solution and stir to obtain a homogeneous mixed aqueous solution; Based on the mass of water, the amount of ethanol solvent added was 4 wt%; the amount of polyethyleneimine added was 2 wt%. Step 2: Add hydroxypropyl cellulose powder to the mixed aqueous solution and stir quickly to dissolve; then place the hydroxypropyl cellulose mixture in a centrifuge to remove air bubbles, and self-assemble photonic crystals at 20~30 ℃ until a uniform structural color appears, to obtain the recyclable 3D printing thermosensitive cellulose photonic ink; The viscosity of hydroxypropyl cellulose is 2.9 mPa•s, and its mass fraction is 68 wt% based on the total mass of the final photonic ink; the centrifuge speed is 4500 rpm and the time is 5 min; the assembly time is 4 weeks.

[0028] The above description is not intended to limit the present invention in any way. Although the present invention has been disclosed through the above embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a recyclable 3D printing temperature-sensitive cellulose photonic ink, characterized in that, Includes the following steps: S1. Both the alcohol solvent and the supramolecular solvent are added to the aqueous solution, and a homogeneous mixed aqueous solution is obtained by stirring; wherein, based on the mass of water, the amount of alcohol solvent added is 1 wt% to 5 wt%; and the amount of supramolecular solvent added is 0 wt% to 2 wt%. S2. Add hydroxypropyl cellulose powder to the mixed aqueous solution and stir quickly to dissolve; then place the hydroxypropyl cellulose mixed solution in a centrifuge to remove air bubbles, and self-assemble photonic crystals at 20~30℃ until a uniform structural color appears, to obtain the recyclable 3D printing thermosensitive cellulose photonic ink; The hydroxypropyl cellulose content is 60 wt% to 80 wt%, based on the total mass of the final photonic ink.

2. The method for preparing a recyclable 3D printing temperature-sensitive cellulose photonic ink according to claim 1, characterized in that, The alcohol solvent in step S1 is one or more of methanol, ethanol, ethylene glycol, and propylene glycol.

3. The method for preparing a recyclable 3D printing temperature-sensitive cellulose photonic ink according to claim 1, characterized in that, The supramolecular solvent in step S1 is one or more of polyethyleneimine, poly(2-dimethylaminoethyl methacrylate), and polyamide.

4. The method for preparing a recyclable 3D printing temperature-sensitive cellulose photonic ink according to claim 1, characterized in that, The hydroxypropyl cellulose in step S2 includes one or more of the following: viscosity of 2.0~2.9 mPa•s, 3.0~6 mPa•s, 6.0~10.0 mPa•s, and 150~400 mPa•s.

5. The method for preparing a recyclable 3D printing temperature-sensitive cellulose photonic ink according to claim 1, characterized in that, In step S2, the centrifuge speed is 3000~5000 rpm and the time is 3~5 minutes.

6. The method for preparing a recyclable 3D printing temperature-sensitive cellulose photonic ink according to claim 1, characterized in that, The self-assembly time in step S2 is 2 to 4 weeks.

7. A recyclable 3D printing temperature-sensitive cellulose photonic ink, characterized in that, It is prepared by any one of the preparation methods according to claims 1 to 6.

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