阅读说明：本技术 基于碳量子点的多色荧光透明木材的制备方法及透明木材 (Preparation method of multicolor fluorescent transparent wood based on carbon quantum dots and transparent wood ) 是由 吴燕 甘健 吴新宇 王雅婧 王晶 张海桥 于 2021-07-21 设计创作，主要内容包括：本发明提供了本发明中对木材进行常规干燥处理,将干燥后的木材浸泡在纯水、次氯酸钠和冰醋酸的混合液中,并经过脱水等后续步骤制得脱木素薄木。使用溶剂热法将木质素与不同含氮化合物脱水碳化反应制得具有不同荧光性能的碳量子点溶液,然后将脱木素薄木真空浸渍在碳量子点溶液中,使碳量子点均匀分布在木材细胞腔内表面,再将脱木质素薄木浸渍在光固化树脂中已填充其细胞腔,经紫外固化后制得基于碳量子的多色荧光透明木材。本发明以碱木质素为碳源,制备出绿色与橙红色发光的碳量子点,并将它们按照不同比例混合以拓展出多色碳量子点浸渍液。(The invention provides a method for preparing delignified veneer by carrying out conventional drying treatment on wood, soaking the dried wood in a mixed solution of pure water, sodium hypochlorite and glacial acetic acid, and carrying out subsequent steps such as dehydration and the like. The method comprises the steps of dehydrating and carbonizing lignin and different nitrogen-containing compounds by using a solvothermal method to prepare carbon quantum dot solutions with different fluorescence properties, then vacuum-dipping delignified veneers in the carbon quantum dot solutions to enable carbon quantum dots to be uniformly distributed on the inner surfaces of wood cell cavities, then dipping the delignified veneers in photocuring resin to fill the cell cavities, and carrying out ultraviolet curing to obtain the carbon quantum-based multicolor fluorescent transparent wood. The invention takes alkali lignin as a carbon source to prepare green and orange-red luminous carbon quantum dots, and the green and orange-red luminous carbon quantum dots are mixed according to different proportions to develop the multicolor carbon quantum dot impregnation liquid.)

1. The preparation method of the multicolor fluorescent transparent wood based on the carbon quantum dots is characterized by comprising the following steps: the method comprises the following steps:

(1): selecting a veneer sample, and drying at the temperature of 80-90 ℃ for 12h to an absolute dry state for later use;

(2): mixing sodium hypochlorite and distilled water, stirring uniformly, adjusting the pH of the mixed solution to 4.6 by using glacial acetic acid to prepare a delignification aqueous solution, soaking the veneer sample dried in the step (1) in the delignification aqueous solution, and heating in a water bath at 85 ℃ for 4-8h to carry out delignification treatment until the veneer sample is in a white state;

(3): taking out the delignified veneer sample in the step (2), washing with deionized water, storing in absolute ethyl alcohol, and performing dehydration treatment to obtain a delignified veneer template;

(4): weighing alkali lignin and p-phenylenediamine, adding the alkali lignin and the p-phenylenediamine into a sulfuric acid solution, uniformly mixing, placing the mixture into a reaction kettle lined with polytetrafluoroethylene, heating the mixture in an oven at 180 ℃ for 8 hours, taking out the mixed solution in the reaction kettle, placing the mixture into a centrifugal machine for solid-liquid separation treatment, dialyzing supernate obtained by centrifugation, freeze-drying the obtained dialysate to obtain powder, and re-dissolving the powder into absolute ethyl alcohol to obtain carbon quantum dot impregnating solution A with green fluorescence;

weighing alkali lignin, o-phenylenediamine and terephthalic acid, adding the alkali lignin, the o-phenylenediamine and the terephthalic acid into absolute ethyl alcohol, uniformly mixing, placing the mixture into a reaction kettle lined with polytetrafluoroethylene, heating the mixture in an oven at 200 ℃ for 10 hours, taking out the mixed solution in the reaction kettle, placing the mixture into a centrifugal machine for solid-liquid separation treatment, dialyzing the supernatant obtained by centrifugation, freeze-drying the obtained dialysate to obtain powder, and re-dissolving the powder in the absolute ethyl alcohol to obtain carbon quantum dot impregnating solution B with orange-red fluorescence;

mixing the carbon quantum dot impregnation liquid A and the carbon quantum dot impregnation liquid B according to a set proportion to prepare a multicolor carbon quantum dot impregnation liquid C;

(5) soaking the delignified veneer prepared in the step (3) in the carbon quantum dot soaking solution A, the carbon quantum dot soaking solution B and the carbon quantum dot soaking solution C prepared in the step (4), and placing the delignified veneer in a vacuum drying kettle for soaking for 40 min;

(6): and (3) taking out the delignified veneer soaked with the multicolor carbon quantum dot soaking solution prepared in the step (5), soaking the delignified veneer in the photocuring resin again, performing vacuum negative pressure treatment, taking out the soaked delignified veneer, and curing the delignified veneer under a 365nm ultraviolet lamp for 5 min to obtain the multicolor fluorescent transparent wood.

2. The method for preparing multicolor fluorescent transparent wood based on carbon quantum dots according to claim 1, characterized in that: the thin wood sample in the step (1) is white poplar, the size of the thin wood sample is 20mm by 1.5mm, and the air-dried density of the thin wood sample is 0.113g/cm³Absolute dry density of 0.087g/cm³。

3. The method for preparing multicolor fluorescent transparent wood based on carbon quantum dots according to claim 1, characterized in that: the bath ratio of the wood flakes to the delignifying aqueous solution in the step (2) is 2.8:1 by mass volume, and the concentration of the sodium hypochlorite aqueous solution in the delignifying aqueous solution is 4 wt%.

4. The method for preparing multicolor fluorescent transparent wood based on carbon quantum dots according to claim 1, characterized in that: the mass ratio of the alkali lignin to the p-phenylenediamine in the step (4) is 1:3, and the concentration of the sulfuric acid solution is 40 wt%.

5. The method for preparing multicolor fluorescent transparent wood based on carbon quantum dots according to claim 1, characterized in that: in the step (4), the mass ratio of the alkali lignin, the o-phenylenediamine and the terephthalic acid is 1:3: 3.

6. The method for preparing multicolor fluorescent transparent wood based on carbon quantum dots according to claim 1, characterized in that: and (3) in the step (4), the solid-liquid separation treatment condition is that the centrifugal rotation speed is 10000 r/min, the centrifugal time is 15 min, a dialysis bag with the molecular interception amount of 1000Da is used for dialysis treatment, the dialysis time is 48h, and the mass-volume ratio of the powder to the absolute ethyl alcohol is 10: 1.

7. The method for preparing multicolor fluorescent transparent wood based on carbon quantum dots according to claim 1, characterized in that: the set ratio in step (4) is 0.8: 1.

8. The method for preparing multicolor fluorescent transparent wood based on carbon quantum dots according to claim 1, characterized in that: in the step (6), the light-cured resin is binary mixed resin of urethane acrylate and epoxy acrylate, and the mass ratio of the urethane acrylate to the epoxy acrylate is 1: 1.

9. The method for preparing multicolor fluorescent transparent wood based on carbon quantum dots according to claim 1, characterized in that: the vacuum negative pressure treatment condition in the step (6) is-1 kg/cm²。

10. A multicolor fluorescent transparent wood prepared by the method for preparing multicolor fluorescent transparent wood based on carbon quantum dots according to any one of claims 1 to 9.

Technical Field

The invention belongs to the field of novel wood technology development and modification, and particularly relates to a preparation method of multicolor fluorescent transparent wood based on carbon quantum dots and the transparent wood.

Background

Forest resources are renewable energy sources, and wood is widely applied to various fields as a widely-existing natural material. The layered porous structure and chemical function of the cellulose framework inside the wood gives it a wider range of modifiability. With the help of this particular structure researchers expect to broaden the function and application fields of the wood by modifying the wood.

The transparent wood is a novel material modified based on wood, can basically keep the mechanical property of the wood and has higher light transmittance. The transparent wood is prepared by injecting transparent polymer with refractive index matched with cell wall components of a sample into delignified wood to fill cell cavities, ducts and the like of the delignified wood.

Quantum dots are of interest as a new class of luminescent materials because of their unique biocompatibility (non-toxicity) and optical properties (emission tunability and photostability). Current research indicates that carbon quantum dots have been used in various fields including bio-imaging, biosensors, metal ion detection, optoelectronics, and the like. Lignin is the most abundant aromatic bio-based macromolecule in nature and is one of ideal materials for preparing carbon quantum dots. However, the existing fluorescent transparent wood based on carbon quantum has single fluorescence and can not change color, and the fluorescent transparent wood can not be applied to all industries, thereby limiting the application of the fluorescent transparent wood.

Disclosure of Invention

The invention mainly aims to overcome the defects in the prior art and provide a preparation method of multicolor fluorescent transparent wood based on carbon quantum dots and the transparent wood.

The invention provides a preparation method of multicolor fluorescent transparent wood based on carbon quantum dots, which comprises the following steps:

(1): selecting a veneer sample, and drying at the temperature of 80-90 ℃ for 12h to an absolute dry state for later use;

(2): mixing sodium hypochlorite and distilled water, stirring uniformly, adjusting the pH of the mixed solution to 4.6 by using glacial acetic acid to prepare a delignification aqueous solution, soaking the veneer sample dried in the step (1) in the delignification aqueous solution, and heating in a water bath at 85 ℃ for 4-8h to carry out delignification treatment until the veneer sample is in a white state;

(3): taking out the delignified veneer sample in the step (2), washing with deionized water, storing in absolute ethyl alcohol, and performing dehydration treatment to obtain a delignified veneer template;

(4): weighing alkali lignin and p-phenylenediamine, adding the alkali lignin and the p-phenylenediamine into a sulfuric acid solution, uniformly mixing, placing the mixture into a reaction kettle lined with polytetrafluoroethylene, heating the mixture in an oven at 180 ℃ for 8 hours, taking out the mixed solution in the reaction kettle, placing the mixture into a centrifugal machine for solid-liquid separation treatment, dialyzing supernate obtained by centrifugation, freeze-drying the obtained dialysate to obtain powder, and re-dissolving the powder into absolute ethyl alcohol to obtain carbon quantum dot impregnating solution A with green fluorescence;

weighing alkali lignin, p-phenylenediamine and terephthalic acid, adding the alkali lignin, the p-phenylenediamine and the terephthalic acid into absolute ethyl alcohol, uniformly mixing, placing the mixture into a reaction kettle lined with polytetrafluoroethylene, heating the mixture in an oven at 200 ℃ for 10 hours, taking out the mixed solution in the reaction kettle, placing the mixture into a centrifugal machine for solid-liquid separation treatment, dialyzing the supernatant obtained by centrifugation, freeze-drying the obtained dialysate to obtain powder, and re-dissolving the powder in the absolute ethyl alcohol to obtain carbon quantum dot impregnating solution B with orange-red fluorescence;

mixing the carbon quantum dot impregnating solution A and the carbon quantum dot impregnating solution B according to a set proportion to prepare a multicolor carbon quantum dot impregnating solution C,

(5): soaking the delignified veneer prepared in the step (3) in the carbon quantum dot soaking solution A, the carbon quantum dot soaking solution B and the carbon quantum dot soaking solution C prepared in the step (4), and placing the delignified veneer in a vacuum drying kettle for soaking for 40 min;

(6): and (3) taking out the delignified veneer soaked with the multicolor carbon quantum dot soaking solution prepared in the step (5), soaking the delignified veneer in the photocuring resin again, performing vacuum negative pressure treatment, taking out the soaked delignified veneer, and curing the delignified veneer under a 365nm ultraviolet lamp for 5 min to obtain the multicolor fluorescent transparent wood.

Preferably, the sample of veneer in step (1) is aspen wood, has a size of 20mm by 1.5mm, and has an air-dried density of 0.113g/cm³Absolute dry density of 0.087g/cm³。

Preferably, the mass-to-volume ratio of the wood flakes to the delignifying aqueous solution in step (2) is 2.8:1 in mg/ml, and the concentration of the sodium hypochlorite aqueous solution in the delignifying aqueous solution is 4 wt%.

Preferably, the mass ratio of the alkali lignin to the p-phenylenediamine in the step (4) is 1:3, and the concentration of the sulfuric acid solution is 40 wt%.

Preferably, the mass ratio of the alkali lignin, the o-phenylenediamine and the terephthalic acid in the step (4) is 1:3: 3.

Preferably, in the step (4), the solid-liquid separation treatment condition is 10000 r/min of centrifugal rotation speed, the centrifugal time is 15 min, a dialysis bag with the molecular cut-off of 1000Da is used for dialysis treatment, the dialysis time is 48h, and the mass-to-volume ratio of the powder to the absolute ethyl alcohol is 10:1, and the unit is mg/ml.

Preferably, the set ratio in step (4) is 0.8: 1.

Preferably, the photocurable resin in the step (6) is a binary mixed resin of urethane acrylate and epoxy acrylate, and the mass ratio of the urethane acrylate to the epoxy acrylate is 1: 1.

Preferably, the vacuum negative pressure treatment in the step (6) is carried out under conditions of-1 kg/cm²。

The invention also provides the multicolor fluorescent transparent wood prepared by the preparation method of the multicolor fluorescent transparent wood based on the carbon quantum dots.

Compared with the prior art, the invention has the beneficial effects that:

1. the method takes alkali lignin as a carbon source, prepares green and orange-red luminous carbon quantum dots, and mixes the green and orange-red luminous carbon quantum dots according to different proportions to expand a multicolor carbon quantum dot impregnation liquid;

2. the invention takes delignified poplar as a dispersion carrier, and disperses carbon quantum dots in a porous structure of the delignified poplar so as to solve the problem of solid-state fluorescence quenching of the carbon quantum dots and realize solid-state luminescence of the delignified poplar.

3. The light-cured resin is used for replacing the traditional epoxy resin to prepare the transparent wood, so that the problem that the transparent wood is easy to oxidize and yellow when exposed in air is solved, the curing process of the transparent wood is simplified, and the curing time of the transparent wood is greatly shortened.

The foregoing is only an overview of the technical solutions of the present invention, and in order to more clearly understand the technical solutions of the present invention, the present invention is further described below with reference to the accompanying drawings.

Drawings

FIG. 1 is a flow chart of the preparation process of the present invention.

Detailed Description

In order to understand the present invention, the following examples are given to further illustrate the present invention. Among them, a light curing agent.

Example 1

The preparation method of the multicolor fluorescent transparent wood based on the carbon quantum dots comprises the following steps:

(1): selecting a poplar veneer sample with the size of 20mm by 1.5mm, drying the poplar veneer sample at the temperature of 80 ℃ for 12h to be in an absolute dry state, and enabling the density of the dried veneer sample to be 0.087g/cm³Standby;

(2): mixing 20g of sodium hypochlorite and 500ml of distilled water, stirring uniformly, adjusting the pH of the mixed solution to 4.6 by using glacial acetic acid to prepare a delignification aqueous solution, soaking 1.044g of the veneer sample dried in the step (1) in the delignification aqueous solution, and heating in a water bath at 85 ℃ for 8 hours to carry out delignification treatment until the veneer sample is in a white state;

(3): taking out the delignified veneer sample in the step (2), washing with deionized water, storing in absolute ethyl alcohol, and performing dehydration treatment to obtain a delignified veneer template;

(4): weighing 0.1g of alkali lignin and 0.3g of p-phenylenediamine, adding the alkali lignin and the p-phenylenediamine into 10ml of 40wt% sulfuric acid solution, uniformly mixing, placing the mixture into a reaction kettle lined with polytetrafluoroethylene, heating the mixture in an oven at 180 ℃ for 8 hours, taking out the mixed solution in the reaction kettle, placing the mixture into a centrifugal machine for solid-liquid separation treatment, carrying out centrifugation at the rotation speed of 10000 r/min for 15 minutes, using a dialysis bag with the molecular cut-off of 1000Da on the supernatant obtained by centrifugation, carrying out dialysis for 48 hours, carrying out freeze drying on the obtained dialysate to obtain powder, dissolving 0.01g of freeze-dried powder into 10ml of absolute ethyl alcohol again, and preparing the carbon quantum dot impregnating solution A with green fluorescence;

(5): soaking the delignified veneer prepared in the step (3) in 10ml of the carbon quantum dot soaking solution A prepared in the step (4), and placing the delignified veneer in a vacuum drying kettle for soaking for 40 min;

(6): and (3) taking out the delignified veneer soaked with the carbon quantum dot soaking liquid A prepared in the step (5), soaking the delignified veneer in light curing resin mixed by 20g of urethane acrylate and 20g of epoxy acrylate again, performing vacuum negative pressure treatment, taking out the delignified veneer after soaking, and curing the delignified veneer under a 365nm ultraviolet lamp for 5 min to obtain the fluorescent transparent wood based on carbon quantum.

The test shows that the transparent wood prepared by the embodiment has the light transmittance of 83 percent and the haze of 71 percent, and is green fluorescence under the excitation of a 365nm ultraviolet lamp.

Example 2

(1): selecting a poplar veneer sample with the size of 20mm by 1.5mm, drying the poplar veneer sample at the temperature of 85 ℃ for 12h to be in an absolute dry state, and enabling the density of the dried veneer sample to be 0.087g/cm³Standby;

(2): mixing 20g of sodium hypochlorite and 500ml of distilled water, stirring uniformly, adjusting the pH of the mixed solution to 4.6 by using glacial acetic acid to prepare a delignification aqueous solution, soaking 1.044g of the veneer sample dried in the step (1) in the delignification aqueous solution, and heating in a water bath at 85 ℃ for 8 hours to carry out delignification treatment until the veneer sample is in a white state;

(3): taking out the delignified veneer sample in the step (2), washing with deionized water, storing in absolute ethyl alcohol, and performing dehydration treatment to obtain a delignified veneer template;

(4): weighing 0.1g of alkali lignin, 0.3g of o-phenylenediamine and 0.3g of terephthalic acid, adding the alkali lignin, the o-phenylenediamine and the terephthalic acid into 10ml of absolute ethyl alcohol, uniformly mixing, placing the mixture into a reaction kettle lined with polytetrafluoroethylene, heating the mixture in an oven at 200 ℃ for 10 hours, taking out the mixed solution in the reaction kettle, placing the mixture into a centrifugal machine for solid-liquid separation treatment, carrying out centrifugation at 10000 r/min for 15 minutes, using a dialysis bag with the molecular cut-off of 1000Da on the supernatant obtained by centrifugation, carrying out dialysis for 48 hours to obtain dialysate, carrying out freeze drying treatment on the dialysate to obtain powder, dissolving 0.01g of the freeze-dried powder into 10ml of absolute ethyl alcohol again, and obtaining carbon quantum dot impregnating solution B with orange-red fluorescence;

(5): soaking the delignified veneer prepared in the step (3) in the carbon quantum dot soaking solution B prepared in the step (4), and placing the delignified veneer in a vacuum drying kettle for soaking for 40 min;

(6): and (3) taking out the delignified veneer soaked with the carbon quantum dot soaking solution B prepared in the step (6), soaking the delignified veneer in light curing resin mixed by 20g of urethane acrylate and 20g of epoxy acrylate again, performing vacuum negative pressure treatment, taking out the delignified veneer after soaking, and curing the delignified veneer under a 365nm ultraviolet lamp for 5 min to obtain the fluorescent transparent wood based on carbon quantum.

The test shows that the light transmittance of the transparent wood prepared by the embodiment is 85%, the haze is 73%, and the transparent wood is orange fluorescence under the excitation of a 365nm ultraviolet lamp.

Example 3

(1): selecting a poplar veneer sample with the size of 20mm by 1.5mm, drying the poplar veneer sample at 90 ℃ for 12h to be in an absolute dry state, wherein the density of the dried veneer sample is 0.087g/cm³Standby;

(2): mixing 20g of sodium hypochlorite and 500ml of distilled water, stirring uniformly, adjusting the pH of the mixed solution to 4.6 by using glacial acetic acid to prepare a delignification aqueous solution, soaking 1.044g of the veneer sample dried in the step (1) in the delignification aqueous solution, and heating in a water bath at 85 ℃ for 8 hours to carry out delignification treatment until the veneer sample is in a white state;

(3): taking out the delignified veneer sample in the step (2), washing with deionized water, storing in absolute ethyl alcohol, and performing dehydration treatment to obtain a delignified veneer template;

(4): weighing 0.1g of alkali lignin and 0.3g of p-phenylenediamine, adding the alkali lignin and the p-phenylenediamine into 10ml of 40wt% sulfuric acid solution, uniformly mixing, placing the mixture into a reaction kettle lined with polytetrafluoroethylene, heating at 180 ℃ for 8 hours, taking out the mixed solution in the reaction kettle, placing the mixed solution into a centrifugal machine for solid-liquid separation treatment, carrying out centrifugation at the rotation speed of 10000 r/min for 15 minutes, using a dialysis bag with the molecular cut-off of 1000Da on the supernatant obtained by centrifugation, carrying out dialysis for 48 hours, carrying out freeze drying on the obtained dialysate to obtain powder, and dissolving the powder in 10ml of absolute ethyl alcohol again to obtain carbon quantum dot impregnating solution A with green fluorescence;

weighing 0.1g of alkali lignin, 0.3g of o-phenylenediamine and 0.3g of terephthalic acid, adding the alkali lignin, the o-phenylenediamine and the terephthalic acid into 10ml of absolute ethyl alcohol, uniformly mixing, placing the mixture into a reaction kettle lined with polytetrafluoroethylene, heating the mixture in an oven at 200 ℃ for 10 hours, taking out the mixed solution in the reaction kettle, placing the mixture into a centrifugal machine for solid-liquid separation treatment, carrying out centrifugation at the rotation speed of 10000 r/min for 15 minutes, using a dialysis bag with the molecular cut-off of 1000Da on the supernatant obtained by centrifugation, carrying out dialysis for 48 hours to obtain dialysate, carrying out freeze drying treatment on the dialysate to obtain powder, dissolving 0.01g of freeze-dried powder into 10ml of absolute ethyl alcohol again to obtain carbon quantum dot impregnating solution B with orange-red fluorescence;

mixing 4 ml of carbon quantum dot impregnation liquid A and 5 ml of carbon quantum dot impregnation liquid B to prepare carbon quantum dot impregnation liquid C;

(5): soaking the delignified veneer prepared in the step (3) in the prepared carbon quantum dot soaking solution C, and placing the delignified veneer in a vacuum drying kettle for soaking for 40 min;

(6): and (3) taking out the delignified veneer soaked with the multicolor carbon quantum dot soaking solution prepared in the step (5), soaking the delignified veneer in light curing resin mixed by 20g of urethane acrylate and 20g of epoxy acrylate again, performing vacuum negative pressure treatment, taking out the delignified veneer after soaking, and curing the delignified veneer under a 365nm ultraviolet lamp for 5 min to obtain the fluorescent transparent wood based on carbon quantum.

The transparent wood obtained in the example has the light transmittance of 86% and the haze of 75%, and is yellow fluorescent under the excitation of a 365nm ultraviolet lamp.

According to the method, the wood is subjected to conventional drying treatment, the dried wood is soaked in a mixed solution of pure water, sodium hypochlorite and glacial acetic acid, lignin is removed, and the delignified veneer is prepared through the steps of dehydration and the like. The method comprises the steps of dehydrating and carbonizing alkali lignin and different nitrogen-containing compounds by a solvothermal method to prepare carbon quantum dot solutions with different fluorescence properties, then vacuum-dipping delignified veneers in the carbon quantum dot solutions to enable carbon quantum dots to be uniformly distributed on the inner surfaces of wood cell cavities, then dipping the delignified veneers in photocuring resin to fill the cell cavities, and carrying out ultraviolet curing to obtain the carbon quantum-based multicolor fluorescent transparent wood.

The fluorescent transparent wood prepared by the method has optical transmittance of more than 80 percent and optical haze of more than 70 percent, and can emit fluorescent light with different colors after being excited by an ultraviolet lamp. The prepared carbon quantum dots have high quantum yield and stable fluorescence performance. The layered structure of the wood tissue is well preserved, the process is simple and environment-friendly, the prepared material has light weight, and the mechanical property is improved compared with the original wood. The fluorescent transparent wood can be applied to the fields of color-changing show windows, fluorescent conversion, uniform illumination and the like.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.