阅读说明：本技术 一种温敏聚合物修饰的碳纳米管复合材料及其制备方法 (Temperature-sensitive polymer modified carbon nanotube composite material and preparation method thereof ) 是由 陈勇 孙陆逸 孙培入 王松 段宏林 于 2020-06-05 设计创作，主要内容包括：本发明公开了一种温敏聚合物修饰的碳纳米管复合材料及其制备方法,通过在多壁碳纳米管表面的炔基和嵌段共聚物链端叠氮基之间点击化学反应制备得到温敏聚合物修饰的碳纳米管复合材料,该材料显著改善了碳纳米管在试剂中的溶解性与分散性,同时能够保持碳纳米管结构与其优良物理性能,此外新的修饰聚合物与碳纳米管也有足够强的结合力。(The invention discloses a temperature-sensitive polymer modified carbon nanotube composite material and a preparation method thereof, wherein the temperature-sensitive polymer modified carbon nanotube composite material is prepared by click chemical reaction between alkynyl on the surface of a multi-wall carbon nanotube and block copolymer chain-end azido, the material obviously improves the solubility and the dispersibility of the carbon nanotube in a reagent, and simultaneously can keep the structure and the excellent physical properties of the carbon nanotube, and in addition, the novel modified polymer has strong enough binding force with the carbon nanotube.)

1. A temperature-sensitive polymer modified carbon nanotube composite material is characterized in that the structural formula is as follows:

wherein R is a poly-N, N-dimethylacrylamide/poly-N-isopropylacrylamide block copolymer.

2. The preparation method of the temperature-sensitive polymer modified carbon nanotube composite material according to claim 1, characterized by comprising the following steps:

(1) dispersing multi-walled carbon nanotubes with hydroxyl on the surface in toluene-2, 4-diisocyanate, reacting for 72 hours at 70-90 ℃ under the protection of nitrogen, filtering and washing reaction products, and drying in vacuum to obtain preliminarily modified multi-walled carbon nanotubes;

(2) taking 1-100 mg of the preliminarily modified multi-walled carbon nano-tube, injecting anhydrous toluene under the protection of nitrogen, adding propargyl alcohol after ultrasonic dispersion, carrying out reflux reaction at 90-110 ℃ for 48h, and carrying out suction filtration, washing and drying after the reaction is finished to obtain the alkynyl-modified multi-walled carbon nano-tube;

(3) taking 1-4mg of the alkynylated multi-walled carbon nanotube, dispersing with water, performing ultrasonic treatment, mixing with the dissolved poly-N, N-dimethylacrylamide/poly-N-isopropylacrylamide block copolymer, raising the temperature of a reaction system to 40-60 ℃, and adding 1-71.2 mg of sodium ascorbate and 1-36.0 mg of copper sulfate pentahydrate;

(4) and (3) keeping the reaction system at 40-60 ℃ for reacting for 24h, and then filtering, washing and vacuum drying to obtain the temperature-sensitive polymer modified carbon nanotube composite material.

3. The method of claim 2, wherein: the number of layers of the multi-walled carbon nanotube in the step (1) is 2-100.

4. The production method according to claim 2 or 3, characterized in that: and (3) mixing the alkynyl-modified multi-walled carbon nanotube with a poly (N, N-dimethylacrylamide)/poly (N-isopropylacrylamide) block copolymer, wherein the concentration of the poly (N, N-dimethylacrylamide)/poly (N-isopropylacrylamide) block copolymer is 1-3 mg/mL.

5. The method of claim 2, wherein: in the step (1), 1-100 mg of the multi-walled carbon nanotube with hydroxyl on the surface is dispersed in 1-50 ml of toluene-2, 4-diisocyanate.

6. The method of claim 4, wherein: the vacuum drying in the steps (2) and (4) is vacuum drying for 24 hours at the temperature of 30-50 ℃.

Technical Field

The invention relates to the technical field of new materials, in particular to a temperature-sensitive polymer modified carbon nanotube composite material and a preparation method thereof.

Background

Since the discovery of carbon nanotubes in japan Iijima in 1991, great interest has been generated by many scientists due to their unique structure, extremely high mechanical, electrical and chemical stability. The carbon nano tube is a special one-dimensional nano material which is formed by combining high-bonding-energy C ═ C double bonds, has a large pi-pi conjugated system and a very high aspect ratio, and has a plurality of excellent properties, such as heat resistance, corrosion resistance, thermal shock resistance, excellent heat transfer and electrical conductivity, self-lubrication, biocompatibility and the like. A series of comprehensive physical and chemical properties of the carbon nano tube enable the carbon nano tube to have important application prospects in the field of preparing high-performance abrasion-resistant composite materials, and the carbon nano tube composite materials are an important direction for the research of the carbon nano tube.

However, the carbon nanotubes are not soluble in water or organic solvents, and are difficult to be well dispersed and effectively combined in a composite matrix, so that the application field and performance of the carbon nanotubes are limited. The application of carbon nanotubes to the field of composite materials requires two key problems to be solved, namely, the dispersion of the nanotubes and the effective combination with the bulk material. This generally requires surface modification of the carbon nanotubes to allow for efficient dispersion in a selected solvent system, while having appropriate surface functional groups to allow for strong interactions with the bulk material to achieve effective bonding with the bulk material.

Disclosure of Invention

In view of this, the invention provides a temperature-sensitive polymer modified carbon nanotube composite material and a preparation method thereof.

The key point of the research is to explore a new method for modifying the surface of the carbon nano tube, and a new method for introducing a temperature-sensitive polymer into the surface of the carbon nano tube is researched by adopting a means of combining surface chemical treatment and covalent modification, so that a new temperature-sensitive polymer modified carbon nano tube composite material is synthesized.

The technical scheme is as follows:

the key point of the temperature-sensitive polymer modified carbon nanotube composite material is that the structural formula is as follows:

wherein R is a poly-N, N-dimethylacrylamide/poly-N-isopropylacrylamide block copolymer.

The second object of the present invention is:

the preparation method of the temperature-sensitive polymer modified carbon nanotube composite material is characterized by comprising the following steps:

(1) dispersing multi-walled carbon nanotubes with hydroxyl on the surface in toluene-2, 4-diisocyanate, reacting for 72 hours at 70-90 ℃ under the protection of nitrogen, filtering and washing reaction products, and drying in vacuum to obtain preliminarily modified multi-walled carbon nanotubes;

(2) taking 1-100 mg of the preliminarily modified multi-walled carbon nano-tube, injecting anhydrous toluene under the protection of nitrogen, adding propargyl alcohol after ultrasonic dispersion, carrying out reflux reaction at 90-110 ℃ for 48h, and carrying out suction filtration, washing and drying after the reaction is finished to obtain the alkynyl-modified multi-walled carbon nano-tube;

(3) taking 1-4mg of the alkynylated multi-walled carbon nanotube, dispersing with water, performing ultrasonic treatment, mixing with the dissolved poly-N, N-dimethylacrylamide/poly-N-isopropylacrylamide block copolymer, raising the temperature of a reaction system to 40-60 ℃, and adding 1-71.2 mg of sodium ascorbate and 1-36.0 mg of copper sulfate pentahydrate;

(4) and (3) keeping the reaction system at 40-60 ℃ for reacting for 24h, filtering, washing and drying in vacuum to obtain the temperature-sensitive polymer covalently modified carbon nanotube composite material.

The number of layers of the multi-walled carbon nanotube in the step (1) is 2-100.

And (3) mixing the alkynyl-modified multi-walled carbon nanotube and a poly (N, N-dimethylacrylamide)/poly (N-isopropylacrylamide) block copolymer in the step (2), wherein the concentration of the poly (N, N-dimethylacrylamide)/poly (N-isopropylacrylamide) block copolymer is 1-3 mg/mL.

In the step (1), 1-100 mg of the multi-walled carbon nanotube with hydroxyl on the surface is dispersed in 1-50 ml of toluene-2, 4-diisocyanate.

The vacuum drying in the steps (2) and (4) is vacuum drying for 24 hours at the temperature of 30-50 ℃.

The invention provides a temperature-sensitive polymer modified carbon nanotube composite material and a preparation method thereof, wherein the temperature-sensitive polymer modified carbon nanotube composite material is prepared by click chemical reaction between alkynyl on the surface of a multi-wall carbon nanotube and block copolymer chain-end azido, and the material can change the surface hydrophilic/hydrophobic properties of the carbon nanotube at different temperatures, and is specifically represented as follows: when the temperature is lower than the critical dissolution temperature (55 ℃) of the poly-N, N-dimethylacrylamide/poly-N-isopropylacrylamide segmented copolymer, the prepared temperature-sensitive polymer modified carbon nano tube has good water dispersibility, and conversely, when the temperature is higher than the critical dissolution temperature (55 ℃) of the copolymer, the prepared temperature-sensitive polymer modified carbon nano tube is gradually agglomerated in water.

Compared with the prior art, the invention has the beneficial effects that: the prepared temperature-sensitive polymer modified carbon nanotube composite material obviously improves the solubility and the dispersibility of the carbon nanotube in a reagent, can keep the structure and the excellent physical property of the carbon nanotube, and has strong enough binding force with the carbon nanotube.

Drawings

FIG. 1 is a reaction scheme of example 1;

FIG. 2 is an infrared spectrum of an alkynyl-modified multi-walled carbon nanotube;

FIG. 3 is a TG curve of an alkynyl-modified multi-walled carbon nanotube;

FIG. 4 is a TGA test result of a covalently modified carbon nanotube composite of poly N, N-dimethylacrylamide/poly N-isopropylacrylamide block copolymer;

FIG. 5 is a TEM characterization of multi-walled carbon nanotubes before and after copolymer modification;

FIG. 6 is a transmission electron microscope analysis of the solubility of a carbon nanotube composite covalently modified with poly-N, N-dimethylacrylamide/poly-N-isopropylacrylamide block copolymer.

Detailed Description

The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention. The starting materials used in the examples are all commercially available products unless otherwise specified.

Example 1, the reaction scheme of this example is shown in figure 1.

1. Dispersing 1-100 mg of multi-walled (2-100 layers of) carbon nanotubes (named as MWNT-OH) with hydroxyl on the surface into 1-50 mL of toluene-2, 4-diisocyanate (TDI), reacting for 72h at 70-90 ℃ under the protection of nitrogen, filtering a reaction product by using a polytetrafluoroethylene membrane (PTFE membrane with the pore diameter of 200nm), washing for several times by using anhydrous toluene to remove residual TDI, and then drying for 24h at 30-50 ℃ in vacuum to obtain the TDI modified multi-walled carbon nanotubes (named as MWNT-NCO);

2. adding 1-100 mg of MWNT-NCO into a 100m L round-bottom flask, injecting 1-15 mL of anhydrous toluene by using an injector under the protection of nitrogen, ultrasonically dispersing for 30min, adding 1-6 mL of propiolic alcohol (PPL), carrying out reflux reaction at 90-110 ℃ for 48h, after the reaction is finished, carrying out suction filtration by using a 200nm PTFE membrane, washing for 3 times by using Tetrahydrofuran (THF), and drying in a vacuum box to obtain an alkynyl-modified multi-walled carbon nanotube which is marked as MWNTs;

the results of the infrared spectroscopic analysis of the raw material MWNT-OH, the intermediate product MWNT-NCO and the MWNTs are respectively shown in FIG. 2, the results of the thermogravimetric curves of the raw material MWNT-OH, the intermediate product MWNT-NCO and the MWNTs are contrastively analyzed, the results are shown in FIG. 3, curves A, B, C in FIGS. 2 and 3 respectively correspond to the MWNT-OH, the MWNT-NCO and the MWNTs, and therefore the alkynyl-modified multi-wall carbon nano-tube is successfully prepared;

3. adding 1-180 mg of poly-N, N-dimethylacrylamide/poly-N-isopropylacrylamide segmented copolymer (the critical solution temperature is 55 ℃, the CAS number is 151954-97-1) and 1-55 mL of water into a 100mL single-neck bottle, raising the reaction temperature to 40-60 ℃ after fully dissolving, dispersing 1-4mg of the alkynyl-modified multi-walled carbon nanotube prepared in the step 2 with 1-5 mL of water, adding into the single-neck bottle after ultrasonic treatment for 5min, keeping the final concentration of the polymer at 1-3 mg/mL, and adding 1-71.2 mg of sodium ascorbate and 1-36.0 mg of copper sulfate pentahydrate;

4. and (2) reacting the reaction mixture at 40-60 ℃ for 24h, filtering the reaction mixture by using a polytetrafluoroethylene membrane (the aperture is 200nm), washing the reaction mixture for several times by using water, ammonia water and methanol to remove residual polymers, and finally drying the reaction mixture in vacuum to obtain the temperature-sensitive polymer poly-N, N-dimethylacrylamide/poly-N-isopropylacrylamide block copolymer covalently modified carbon nanotube composite material.

The comparison of MWNT-DMA508 and MWNT-DMA255-NIPAN227 shows that the thermal weight loss analysis of the poly-N, N-dimethylacrylamide carbon nanotube composite material purchased from the market is performed, and the results are shown in FIG. 4, wherein curves a and b are the thermal weight loss curves of the commercially available MWNT-DMA508 at 30 ℃ and 55 ℃, and curves c and d are the thermal weight loss curves of the MWNT-DMA255-NIPAN at 30 ℃ and 55 ℃, respectively, and the comparison shows that the poly-N, N-dimethylacrylamide/poly-N-isopropylacrylamide block copolymer has been successfully modified on the multi-walled carbon nanotube.

TEM characterization is performed on MWNT-OH as a raw material and the temperature-sensitive polymer poly-modified carbon nanotube composite material prepared in this example, and the results are shown in C and F in FIG. 5, which shows that the original unmodified multi-walled carbon nanotube with hydroxyl (FIG. 5C) is coated with a layer of temperature-sensitive polymer (FIG. 5F) on the periphery after chemical modification.

The solubility of the temperature-sensitive polymer poly-modified carbon nanotube composite material prepared in this example was analyzed by transmission electron microscopy, and the result is shown in fig. 6. Wherein, the graphs A and B show that the temperature-sensitive polymer poly-modified carbon nano tube composite material has poor dispersity at the temperature when the temperature of the aqueous solution is more than 60 ℃, and the graphs D and E show that the temperature-sensitive polymer poly-modified carbon nano tube composite material has good dispersity when the temperature of the aqueous solution is reduced to 40 ℃.

Finally, it should be noted that the above-mentioned description is only a preferred embodiment of the present invention, and those skilled in the art can make various similar representations without departing from the spirit and scope of the present invention.