CN112323491B - Method for carrying out super-hydrophobic modification on waste cotton fabric by dopamine - Google Patents

Abstract

The invention relates to a method for superhydrophobic modification of waste cotton fabric by dopamine. The invention selects waste cotton fabric as a base material, and reuses it while reducing environmental pressure. Dopamine and long-chain alkylamine are used to treat waste cotton fabric. After treatment, modification and modification can be carried out directly without treatment such as decolorization. The surface roughness is improved by constructing micro-nano structures on the surface of waste cotton fabrics with dopamine, and then long-chain alkylamines are used to reduce the surface energy of the waste cotton fabrics, thereby finally obtaining superhydrophobic waste cotton fabrics. The process of the invention is simple, the reaction period is short, the material is environmentally friendly, and the finished super-hydrophobic waste cotton fabric has good durability, etc., and has wide application value such as oil-water separation.

Description

A method for superhydrophobic modification of waste cotton fabrics with dopamine

technical field

The invention relates to a modification technology of waste cotton fabrics, in particular to a method for superhydrophobic modification of waste cotton fabrics by dopamine.

Background technique

Cotton fabric is a common natural fiber fabric, which is widely loved by people due to its natural origin and comfortable wearing properties. With the ever-changing demand for clothing, the demand for textiles is increasing, which has also caused many environmental problems, such as the shortage of raw materials and the accumulation of waste textiles. my country, as a major textile country, data shows that in 2011, the total output of waste textiles in my country exceeded 26 million tons, but only 2.3 million tons were recycled, and the recycling rate was less than 10%. Therefore, how to effectively recycle waste textiles , is an urgent problem to be solved in our country and even the whole world.

Superhydrophobic materials (contact angles over 150°) are materials with special wetting properties, which were originally inspired by the "lotus leaf effect", the nanoscale protrusions and depressions on the surface of the lotus leaf and the binary structure of nanorods. The covered waxy material endows the lotus leaf with super-hydrophobicity. Due to the microscopic rough structure and the waxy substance, an air film is formed on the surface of the water droplets and the lotus leaf, so that the water droplets cannot infiltrate and easily slip off. Superhydrophobic materials have a variety of uses in life, such as oil-water separation, surface self-cleaning, snow protection, corrosion resistance, etc., and have a wide range of application values. So far, there have been a lot of studies on the preparation of superhydrophobic materials, such as plasma etching, sol-gel, electrochemical deposition, template, etc., and since the discovery of dopamine biomimetic mussel chemistry, its The field of surface functional finishing has also aroused the research upsurge of a wide range of researchers, but most of the finishing methods have some problems, such as complicated operation, long reaction period, and the use of fluorine-containing long-chain compounds as low surface energy substances, and this compound has serious problems. environmental issues.

Due to the large number of hydroxyl groups on the surface of cotton fibers, it is easy to be modified, so many studies choose cotton fabrics for modification, but most of the waste cotton textiles have been dyed and finished, treated with chemicals such as dyes, and reused in the process. are affected, so many finishing methods do not work on waste textiles, such as reactive and direct dyes commonly used to dye cotton fabrics. Among them, reactive dyes are used as reactive dyes, and the dyeing mechanism is that the reactive groups of the dyes are combined with the fiber negative ions (Cell-O ^- ) through covalent bonds through nucleophilic addition-elimination substitution reaction (referred to as nucleophilic substitution reaction). It is distributed and fixed on the fiber, so it will cover the hydroxyl groups on the cotton fiber during the dyeing process. If the hydroxyl group on the cotton fabric is reduced in the subsequent finishing, it will not be able to generate enough micro-nano particles on its surface to improve the surface roughness. The degree of hydrophobicity, or the inability to combine with enough hydrophobic compounds to optimize the chemical composition to reduce the surface energy, will have an impact on the hydrophobic effect. Direct dyes are adsorbed on the fiber surface through intermolecular forces such as hydrogen bonds and van der Waals forces. Although there are no "dye bases" such as amino groups and carboxyl groups on protein fibers on the cellulose fiber molecule, there are also specific chemical adsorption sites. When these chemical adsorption sites are occupied by dyes, it is also possible to adsorb modified finishing chemicals. Deposition has an effect, if the adsorption of finishing chemicals to these adsorption sites is weakened, resulting in uneven finishing of chemicals on the surface of the fabric, eventually leading to the "short plate effect". Under these circumstances, waste cotton fabrics often need to undergo dye desorption and other treatments, and then undergo modification finishing, in which the steps are relatively complicated. Therefore, it is very necessary to invent a method for superhydrophobic modification finishing without the need for complex pretreatment such as dye decolorization of waste fabrics.

Dopamine (DA) is an analog of natural catecholamine dopa derived from marine mussel byssin protein. Because it has the same catecholamine structure as dopa, it has similar adhesion to mussel byssin protein. Dopamine can be oxidatively polymerized into polydopamine, but the mechanism is very complicated, and there is no conclusion so far. Combined with the current research, the polymerization mechanism is roughly that the catechol structure is easily oxidatively polymerized to form an o-quinone structure, and then its primary amine group forms a ring and self-polymerizes. The key cyclization product of dopamine, 5,6-dihydroxyindole (DHI), is finally combined to form a supramolecular aggregate of monomers, polydopamine, through charge transfer, π-stacking and hydrogen bonding interactions. Due to the strong covalent/non-covalent interaction between the catechol moiety and the substrate, polydopamine has excellent adhesion and can be deposited on various substrate surfaces.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned technical problems, the object of the present invention is to provide a method for superhydrophobic modification of waste cotton fabrics by dopamine, and the present invention provides a method for superhydrophobic finishing of waste cotton fabrics for reuse, which does not Complicated pre-treatments such as dye decolorization are required for waste cotton fabrics.

The purpose of this invention is to provide a kind of method that dopamine carries out superhydrophobic modification to waste cotton fabric, is made up of the following steps:

(1) In-situ compounding of iron ions: Immerse the waste cotton fabric in a 2-5mM ferric salt aqueous solution at a bath ratio of 1:20-1:50, and treat it in a water bath at 40-60°C for 5-20 minutes to obtain Iron ion complexed cotton fabric;

(2) In-situ complexing and in-situ oxidative polymerization of dopamine: The cotton fabric complexed with iron ions was treated with a dopamine solution of 5-20 mM in a liquor ratio of 1:20 to 1:50. The treatment temperature was 40 to 60 °C, and the treatment time 5 to 30 minutes; then add an oxidant to the solution to oxidize dopamine in situ, and the concentration of the oxidant in the solution is 5 to 20 mM to obtain an oxidatively polymerized cotton fabric, and then the oxidatively polymerized cotton fabric is washed and dried;

(3) Repeated finishing: repeat steps (1)-(2) 1-2 times again to obtain a multi-layer dopamine-coated cotton fabric;

(4) Super-hydrophobic treatment: Immerse the multi-layer dopamine-coated cotton fabric in a solution containing low surface energy substances at a liquor ratio of 1:20-1:50, treat at 40-60°C, wash and dry after finishing the treatment , to obtain a super-hydrophobic cotton fabric; wherein, the low surface energy substances are selected from C ₁₄ -C ₁₈ alkylamines.

Further, before step (1), it also includes the step of cleaning the waste cotton fabric and removing soluble impurities.

Further, in step (1), the waste cotton fabrics include waste white cotton fabrics, cotton fabrics dyed with reactive dyes, dyed with direct dyes or dyed with vat dyes.

In the present invention, the white cotton fabrics with waste raw materials, the cotton fabrics dyed with reactive dyes, dyed with direct dyes and dyed with vat dyes have a hydrophilic angle of 0°, all of which are super-hydrophilic fabrics.

Further, in step (1), the ferric salt is selected from ferric chloride and/or ferric sulfate.

Further, in steps (1)-(2), the processing methods are all vibration processing.

Further, in step (2), the oxidant is selected from sodium perborate and/or hydrogen peroxide.

Further, in step (2), after adding an oxidizing agent, the solution is shaken in a water bath at 40-60° C. for 30-70 minutes.

Further, in step (2), the washing and drying are specifically three times washing with water, and then drying at 60-100° C. after taking out.

Further, in step (3), during the repeated sorting, the repeated sorting is performed in the order of first performing step (1) and then performing (2).

Further, in step (4), the low surface energy substance is selected from one or more of tetradecylamine, hexadecylamine and octadecylamine. Preferred is octadecylamine.

Further, in step (4), in the solution containing the low surface energy substance, the concentration of the low surface energy substance is 1-10 mM.

Further, in step (4), the solvent used in the solution containing the low surface energy substance is ethanol/aqueous solution, wherein the volume ratio of ethanol:water is 5-7:3-5.

Further, in step (4), the treatment time is 2-6 hours.

Further, in step (4), the processing method is vibration processing.

Further, in step (4), the washing is firstly washed with ethanol 3 times, and then washed with water 3 times.

Based on the feature of polydopamine being non-selective to the substrate, the present invention uses polydopamine to perform super-hydrophobic finishing on waste cotton fabrics, and catalyzes the polymerization of dopamine through metal salts and oxidants to promote the polymerization speed of dopamine, so as to accelerate the reaction and improve the The problem of slow dopamine polymerization, this method is fast, efficient and environmentally friendly. Specifically, the principle of the present invention is as follows:

Using the principle of coordination between iron ions and hydroxyl groups, iron ions are compounded on cotton fabrics, and then using the strong coordination of incompletely coordinated iron and dopamine, dopamine is compounded to the surface of cotton fabrics through iron ions, and then oxidizing agents are used to catalyze Oxidation, promotes the oxidative polymerization of dopamine to form an o-quinone structure, and then forms a key cyclization product of dopamine, 5,6-dihydroxyindole (DHI), which is cyclized with its primary amine group, and finally interacts with charge transfer, π stacking and hydrogen bonding. The combination forms a supramolecular aggregate of dopamine—polydopamine, which adheres to the surface of cotton fabric to form a superhydrophobic structure. The invention does not use fluorine-containing compounds in the preparation process, and mainly utilizes polydopamine to rapidly deposit on the surface of cotton fabrics to construct secondary micro-nano rough structures and form a nano air film on the surface of water and cotton fabrics. Finally, the o-benzoquinone structure formed by the oxidation of the catechol structure by the oxidant is used to react with the primary amine group to form a C=N bond, and the low surface energy substance alkylamine is grafted to cover the polydopamine-coated cotton fabric. On the surface, the long carbon chain of alkylamine and the micro-nano structure of polydopamine work together to make the waste cotton fabric achieve super-hydrophobic effect.

By means of the above scheme, the present invention has at least the following advantages:

1. The present invention uses waste textiles as raw materials, which is not only beneficial to solve the environmental pressure and damage caused by waste textiles, but also has low cost and wide sources.

2. Due to its catechol structure, polydopamine has excellent adhesion. It can directly modify waste dyed cotton fabrics without dehydration and other treatments. The modified fabrics have good stability and good durability. , the superhydrophobic waste cotton fabrics prepared by it have a wide range of application prospects.

3. Dopamine is derived from natural animals and plants, and is easy to degrade, so it will not cause secondary pollution to the environment from the finished super-hydrophobic waste fabrics.

4. In the present invention, the micro-nano structure is constructed on the surface of the waste cotton fabric by dopamine to improve the surface roughness, and then long-chain alkylamine is used to reduce the surface energy of the surface of the waste cotton fabric, thereby finally obtaining the superhydrophobic waste cotton fabric. The process of the invention is simple, the reaction period is short, the material is environmentally friendly, and the finished super-hydrophobic waste cotton fabric has good durability, etc., and has wide application value such as oil-water separation.

The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly and implement it according to the content of the description, the preferred embodiments of the present invention are described in detail below.

Detailed ways

The specific embodiments of the present invention will be further described in detail below with reference to the examples. The following examples are intended to illustrate the present invention, but not to limit the scope of the present invention.

Example 1

(1) In-situ coordination of iron ions: Clean the discarded white cotton fabric to remove soluble impurities. The washed cotton fabric was immersed in 2.4mM FeCl ₃ solution at a liquor ratio of 1:40, shaken in a water bath at 50 °C for 10 minutes, and taken out.

(2) In-situ complexing of dopamine: prepare a 10.5 mM dopamine solution, add iron ion complexed cotton fabric to it at a liquor ratio of 1:30, and shake in a 50°C water bath for 10 minutes.

(3) In-situ oxidative polymerization of dopamine: Sodium perborate was added to the in-situ complexed and reacted solution of dopamine to make the concentration of sodium perborate 15 mM, and the solution was shaken in a 50° C. water bath for 60 minutes.

(4) Washing and drying: The in-situ oxidatively polymerized cotton fabric was washed three times with deionization, taken out and dried in an oven at 60°C.

(5) Repeated finishing: the dried and finished cotton fabric is processed once again according to the above-mentioned process steps (1)-(4), and the cotton fabric covered with multiple layers of dopamine is obtained by finishing.

(6) Super-hydrophobic treatment: Immerse the above-mentioned multi-layer dopamine-coated cotton fabric in an ethanol/water solution of 5 mM octadecylamine at a liquor ratio of 1:50 (the volume ratio of ethanol and water is 7:3), at 50° C. The reaction was shaken for 4 hours, taken out, washed three times with ethanol, and then washed with deionized water three times, and then dried to obtain a super-hydrophobic cotton fabric.

Example 2

(1) In-situ coordination of iron ions: Clean the discarded white cotton fabric to remove soluble impurities. Take the cleaned cotton fabric and immerse it in 4mM FeCl3 solution at a liquor ratio _of 1:30, shake it in a water bath at 40°C for 20 minutes, and take it out.

(2) In situ complexing of dopamine: prepare a 20 mM dopamine solution, add iron ion complexed cotton fabric to it at a liquor ratio of 1:30, and shake in a 40° C. water bath for 30 minutes.

(3) In-situ oxidative polymerization of dopamine: hydrogen peroxide was added to the in-situ complexed and reacted solution of dopamine to make the concentration of hydrogen peroxide 20 mM, and the solution was shaken in a water bath at 40° C. for 70 minutes.

(4) Washing and drying: The in-situ oxidatively polymerized cotton fabric was washed three times with deionization, taken out and dried in an oven at 60°C.

(5) Repeated finishing: the dried and finished cotton fabric is treated once again according to the above-mentioned process steps (1)-(4) to obtain a multi-layer dopamine-coated cotton fabric after finishing.

(6) Super-hydrophobic treatment: The above-mentioned multi-layer dopamine-coated cotton fabric was immersed in a 5mM ethanol/water solution of hexadecylamine in a liquor ratio of 1:20 (the volume ratio of ethanol and water was 6:4), and at 40° C. The reaction was shaken for 6 hours, taken out, washed three times with ethanol, then three times with deionized water, and then dried to obtain a super-hydrophobic cotton fabric.

Example 3

(1) In-situ coordination of iron ions: Clean the discarded white cotton fabric to remove soluble impurities. The washed cotton fabric was immersed in a 2mM Fe ₂ (SO ₄ ) ₃ solution at a liquor ratio of 1:50, shaken in a 60° C. water bath for 5 minutes, and taken out.

(2) In situ complexing of dopamine: prepare a 10 mM dopamine solution, add iron ion complexed cotton fabric to it at a liquor ratio of 1:20, and shake in a 60° C. water bath for 10 minutes.

(3) In-situ oxidative polymerization of dopamine: hydrogen peroxide was added to the dopamine in-situ complexed and reacted solution to make the concentration of hydrogen peroxide 15 mM, and the solution was shaken in a 60° C. water bath for 30 minutes.

(4) Washing and drying: The in-situ oxidatively polymerized cotton fabric was washed three times with deionization, taken out and dried in an oven at 60°C.

(5) Repeated finishing: the dried and finished cotton fabric is processed once again according to the above-mentioned process steps (1)-(4), and the cotton fabric covered with multiple layers of dopamine is obtained by finishing.

(6) Super-hydrophobic treatment: The above-mentioned multi-layer dopamine-coated cotton fabric was immersed in an ethanol/water solution of 5 mM tetradecylamine at a liquor ratio of 1:30 (the volume ratio of ethanol and water was 5:5), and the temperature was 60° C. The reaction was shaken for 2 hours, taken out, washed three times with ethanol, and then washed with deionized water three times, and then dried to obtain a super-hydrophobic cotton fabric.

Example 4

(1) In-situ coordination of iron ions: Clean the discarded reactive blue dye-dyed cotton fabrics to remove soluble impurities. Take the cleaned cotton fabric and immerse it in 5mM FeCl3 solution at a liquor ratio _of 1:50, shake it in a water bath at 50 °C for 10 minutes, and take it out.

(2) In situ complexing of dopamine: prepare a 10.5 mM dopamine solution, add iron ion complexed cotton fabric to it at a liquor ratio of 1:50, and shake in a 50°C water bath for 10 minutes.

(3) In-situ oxidative polymerization of dopamine: Sodium perborate was added to the dopamine in-situ complexed and reacted solution to make the concentration of sodium perborate 15 mM, and the solution was shaken in a 50° C. water bath for 70 minutes.

(4) Washing and drying: The in-situ oxidatively polymerized cotton fabric was washed three times with deionization, taken out and dried in an oven at 60°C.

(5) Repeated finishing: the dried and finished cotton fabric is processed once again according to the above-mentioned process steps (1)-(4), and the cotton fabric covered with multiple layers of dopamine is obtained by finishing.

(6) Super-hydrophobic treatment: Immerse the above-mentioned multi-layer dopamine-coated cotton fabric in an ethanol/water solution of 5 mM octadecylamine at a liquor ratio of 1:50 (the volume ratio of ethanol and water is 7:3), at 50° C. The reaction was shaken for 4 hours, taken out, washed three times with ethanol, and then washed with deionized water three times, and then dried to obtain a superhydrophobic reactive blue dyed cotton fabric.

The contact angle of the superhydrophobic reactive blue dyed cotton fabric in this example can reach 158.7±2.56°, so the reactive dye dyed cotton fabric has no effect on this finishing method and still has an excellent superhydrophobic effect.

Example 5

(1) In-situ coordination of iron ions: Clean the discarded cotton fabrics dyed with direct burgundy dye to remove soluble impurities. The washed cotton fabric was immersed in 2.4mM FeCl ₃ solution at a liquor ratio of 1:40, shaken in a water bath at 50 °C for 10 minutes, and taken out.

(2) In situ complexing of dopamine: prepare a 10.5 mM dopamine solution, add iron ion complexed cotton fabric to it at a liquor ratio of 1:40, and shake in a 50°C water bath for 10 minutes.

(3) In-situ oxidative polymerization of dopamine: Sodium perborate was added to the in-situ complexed and reacted solution of dopamine to make the concentration of sodium perborate 10 mM, and the solution was shaken in a water bath at 50° C. for 50 minutes.

(4) Washing and drying: The in-situ oxidatively polymerized cotton fabric was washed three times with deionization, taken out and dried in an oven at 60°C.

(5) Repeated finishing: the dried and finished cotton fabric is processed once again according to the above-mentioned process steps (1)-(4), and the cotton fabric covered with multiple layers of dopamine is obtained by finishing.

(6) Super-hydrophobic treatment: Immerse the above-mentioned multi-layer dopamine-coated cotton fabric in an ethanol/water solution of 5 mM octadecylamine at a liquor ratio of 1:50 (the volume ratio of ethanol and water is 7:3), at 50° C. The reaction was shaken for 4 hours, taken out, washed three times with ethanol, and then washed with deionized water three times, and then dried to obtain a superhydrophobic reactive blue dyed cotton fabric.

The contact angle of the super-hydrophobic direct jujube red-dyed cotton fabric in this example can reach 156.9±2.49°, so the cotton fabric dyed with direct dye has no effect on this finishing method, and still has an excellent super-hydrophobic effect.

Example 6

(1) In-situ coordination of iron ions: Clean the discarded vat pink dyed cotton fabrics to remove soluble impurities. Take the cleaned cotton fabric and immerse it in 2.4mM FeCl3 solution at a liquor ratio _of 1:50, shake it in a water bath at 50 °C for 10 minutes, and take it out.

(2) In-situ complexing of dopamine: prepare a 10.5 mM dopamine solution, add iron ion complexed cotton fabric to it at a liquor ratio of 1:30, and shake in a 50°C water bath for 10 minutes.

(3) In-situ oxidative polymerization of dopamine: Sodium perborate was added to the in-situ complexed and reacted solution of dopamine to make the concentration of sodium perborate 10 mM, and the solution was shaken in a water bath at 50° C. for 50 minutes.

(4) Washing and drying: The in-situ oxidatively polymerized cotton fabric was washed three times with deionization, taken out and dried in an oven at 60°C.

(5) Repeated finishing: the dried and finished cotton fabric is processed once again according to the above-mentioned process steps (1)-(4), and the cotton fabric covered with multiple layers of dopamine is obtained by finishing.

(6) Super-hydrophobic treatment: Immerse the above-mentioned multi-layer dopamine-coated cotton fabric in an ethanol/water solution of 5 mM octadecylamine at a liquor ratio of 1:50 (the volume ratio of ethanol and water is 7:3), at 50° C. The reaction was shaken for 4 hours, taken out, washed three times with ethanol, and then washed with deionized water three times, and then dried to obtain a superhydrophobic reactive blue dyed cotton fabric.

The contact angle of the superhydrophobic reduced pink dyed cotton fabric in this example can reach 155.8±2.38°, so the cotton fabric dyed with direct dye has no effect on this finishing method and still has an excellent superhydrophobic effect.

Table 1 is the water contact angle test results of the raw materials and the prepared superhydrophobic fabrics in Example 1 and Examples 4-6. It can be seen from the table that after finishing by the method of the present invention, the fabrics have excellent superhydrophobic effect.

Table 1 The water contact angles of raw materials and treated fabrics of different embodiments

The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. It should be pointed out that for those skilled in the art, some improvements and modifications can be made without departing from the technical principles of the present invention. , these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims (5)

1. a method for dopamine to carry out superhydrophobic modification to waste cotton fabric, is characterized in that, is made up of the following steps: (1) Immerse the waste cotton fabric in a 2-5mM ferric salt aqueous solution at a liquor ratio of 1:20～1:50, and the treatment temperature is 40～60° C. to obtain a cotton fabric coordinated with iron ions; the ferric iron The salt is selected from ferric chloride and/or ferric sulfate; (2) using a dopamine solution of 5-20 mM in a liquor ratio of 1:20 to 1:50 to treat the iron ion-coordinated cotton fabric at a temperature of 40 to 60° C., and then adding an oxidant to the solution to oxidize dopamine in situ , after adding an oxidant, oscillate in a water bath at 40 to 60°C for 30 to 70 minutes, and the concentration of the oxidant is 5 to 20 mM to obtain an oxidatively polymerized cotton fabric, and then the oxidatively polymerized cotton fabric is washed and dried; the The oxidizing agent is selected from sodium perborate and/or hydrogen peroxide; (3) repeating steps (1) and (2) 1-2 times again to obtain a multi-layer dopamine-coated cotton fabric; (4) immersing the multi-layer dopamine-coated cotton fabric in a solution containing a low surface energy substance at a bath ratio of 1:20-1:50, treating at 40-60° C., washing and drying after the treatment, to obtain Super-hydrophobic cotton fabric; wherein, the low surface energy substance is selected from one or more of tetradecylamine, hexadecylamine and octadecylamine; in the solution containing the low surface energy substance, the The concentration is 1 to 10 mM. 2. The method according to claim 1, characterized in that: in step (1), the waste cotton fabric comprises waste white cotton fabric, cotton dyed with reactive dyes, dyed with direct dyes or dyed with vat dyes fabric. 3. The method according to claim 1, characterized in that: in steps (1)-(2), the processing methods are vibration processing. 4. method according to claim 1, is characterized in that: in step (4), the used solvent of the solution containing low surface energy substance is ethanol/aqueous solution, and wherein ethanol: the volume ratio of water is 5～7: 3 to 5. 5. The method according to claim 1, wherein in step (4), the treatment time is 2-6 hours.