KR102174536B1 - Polyamide-carbon nanotube nanocomposite and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a polyamide-carbon nanotube nanocomposite and a method for manufacturing the same. The polyamide-carbon nanotube nanocomposite of the present invention has excellent dispersibility of carbon nanotubes and improved interfacial compatibility, and thus has very high electrical conductivity. The polyamide-carbon nanotube nanocomposite includes a polyamide-based polymer resin and a carbon nanotube coated with and an isoalloxazine derivative represented by chemical formula 1.

Description

Polyamide-carbon nanotube nanocomposite and method for manufacturing the same}

The present invention relates to a polyamide-carbon nanotube nanocomposite and a method for producing the same.

Polyamide (PA) 6 prepared by ring-opening polymerization of caprolactam is one of the most widely used PA derivatives. PA-based plastics have a wide range of applications because of their excellent strength and wear properties. In addition, reinforced PA began to replace metals in automobile manufacturing due to its light weight and non-corrosive properties, but the insulating properties of PA limit its use as an electrical material. However, when a nanomaterial based on carbon and an inorganic material is bonded to the PA as an external material, a material having a high enough conductivity may be formed to be used as an electromagnetic wave shielding agent and a touch screen film. Double-walled carbon nanotubes (MWNTs) are used as additives to improve electrical properties based on very high conductivity and a high aspect ratio exceeding 100 that can be mechanically reinforced.

The main challenges faced in the manufacture of highly conductive MWNT nanocomposites are to achieve uniform dispersion of MWNTs in the matrix polymer and excellent interfacial adhesion between the MWNTs and the polymer. It is known that the adhesion between the MWNT and the polymer matrix is poor, and when the MWNT aggregates and becomes a lump, it acts as a defect that deteriorates the electrical performance of the nanocomposite.

The adhesion can be improved by introducing a functional group into the MWNT or polymer matrix, and covalently bonded functional groups such as carboxyl groups, amines and hydroxy groups are included by treatment with a strong acid such as a mixture of sulfuric acid and nitric acid. However, in the case of introducing a covalent functional group, the conjugated π network of MWNTs is inevitable and thus the physical properties of MWNTs are deteriorated. As an alternative to this, there is a method of introducing a non-covalent functional group of MWNT using a surfactant. In this method, the surfactant induces a strong interaction between the main chain of the polymer matrix and the sidewall of the MWNT, thereby improving the electrical performance of the nanocomposite.

Naskar, A. K.; Keum, J. K.; Boeman, R. G., Polymer Matrix Nanocomposites for Automotive Structural Components. Nat. Nanotechnol. 2016, 11, 1026. Liu, Y.; Kumar, S., Polymer/Carbon Nanotube Nano Composite Fibers-A Review. ACS Appl. Mater. Interfaces 2014, 6 (9), 6069-6087. Chen, J.; Liu, B.; Gao, X.; Xu, D., A Review of the Interfacial Characteristics of Polymer Nanocomposites containing Carbon Nanotubes. RSC Adv. 2018, 8 (49), 28048-28085.

Accordingly, the technical problem to be solved by the present invention relates to a polyamide-carbon nanotube nanocomposite having very excellent electrical conductivity by improving the dispersibility and interfacial compatibility of carbon nanotubes in polyamide, and a method of manufacturing the same.

One aspect of the present invention is a polyamide-based polymer resin; And carbon nanotubes dispersed in the polyamide-based polymer resin and coated with an isoalloxazine derivative represented by the following Chemical Formula 1. It provides a polyamide-carbon nanotube nanocomposite comprising:

[Formula 1]

In the above formula, R is hydrogen or alkyl having 1 to 6 carbon atoms, and R ₁ to R ₄ are each independently hydrogen, alkyl, hydroxy, halogen atom, halogenated alkyl group, carbonyl group, cyan group, alkoxy group, alkylthio, thio group, It is an allyl group, an aryl group, or a nitrogen heterocycle, and X is a C3-C20 saturated or unsaturated alkyl group.

Another aspect of the present invention is to prepare a dispersion solution in which a surfactant and carbon nanotubes are mixed; Bonding a surfactant to the surface of the carbon nanotubes; Preparing a carbon nanotube coated with an isoalloxazine derivative by heat-treating the carbon nanotube to which the surfactant is bonded to the surface to transform the surfactant into an isoalloxazine derivative represented by the following Formula 1; And it provides a method for producing a polyamide-carbon nanotube nanocomposite comprising; and melt-extruding a mixture of the carbon nanotubes coated with the isoalloxazine derivative and the polyamide-based polymer resin.

The polyamide-carbon nanotube nanocomposite of the present invention has excellent dispersibility of the carbon nanotubes and improved interfacial compatibility, thereby having very high electrical conductivity.

1 is a schematic diagram of a method of manufacturing a polyamide-carbon nanotube nanocomposite according to an embodiment of the present invention.
2 is an actual photograph of a polyamide-carbon nanotube nanocomposite sheet prepared according to an embodiment of the present invention.
3 is an SEM analysis image of a PA-dFMN-MWNT polyamide-carbon nanotube nanocomposite prepared according to an embodiment of the present invention. 3a to c are PA-dFMN-MWNT-1, FIGS. 3d to f are PA-dFMN-MWNT-5, and FIGS. 3g to 3i are SEM analysis results of PA-dFMN-MWNT-10 at different magnifications.
4 is a result of measuring the electrical conductivity of the polyamide-carbon nanotube nanocomposite prepared according to an embodiment of the present invention. 4A is an image of a circuit including a 4.5 V AA battery connected in series with an LED, and PA-dFMN-MWNT-10 used as a resistor, and the inset is a circuit diagram. 4B is a photograph of LEDs in the absence of PA, PA-dFMN-MWNT-3, -5, -10, and polyamide-carbon nanotube nanocomposites. Figure 4c is a graph measuring the electrical conductivity of PA-dFMN-MWNT-3, -5 and -10.
5 is a Raman spectrum analysis result of a polyamide-carbon nanotube nanocomposite prepared according to an embodiment of the present invention.
6 is a result of measuring the mechanical strength of a polyamide-carbon nanotube nanocomposite according to an embodiment of the present invention. 6A is a stress-strain curve of a polyamide-carbon nanotube nanocomposite according to an embodiment of the present invention, and FIG. 6B is a tensile strength and fracture of the polyamide-carbon nanotube nanocomposite according to an embodiment of the present invention. It is the result of measuring elongation.
7 is an FT-IR analysis result of a polyamide-carbon nanotube nanocomposite according to an embodiment of the present invention.

Hereinafter, various aspects and various embodiments of the present invention will be described in more detail.

One aspect of the present invention is a polyamide-based polymer resin; And carbon nanotubes dispersed in the polyamide-based polymer resin and coated with an isoalloxazine derivative represented by the following Chemical Formula 1. It provides a polyamide-carbon nanotube nanocomposite comprising:

[Formula 1]

In the above formula, R is hydrogen or alkyl having 1 to 6 carbon atoms, and R ₁ to R ₄ are each independently hydrogen, alkyl, hydroxy, halogen atom, halogenated alkyl group, carbonyl group, cyan group, alkoxy group, alkylthio, thio group, It is an allyl group, an aryl group, or a nitrogen heterocycle, and X is a C3-C20 saturated or unsaturated alkyl group.

The polyamide-carbon nanotube nanocomposite relates to a composite having excellent electrical conductivity by dispersing carbon nanotubes in a polyamide polymer matrix. Basically, since carbon nanotubes have a property of aggregation between carbon nanotubes, it is very difficult to achieve uniform dispersion in a polymer matrix. In addition, improving the interfacial compatibility between the carbon nanotubes and the polymer matrix is one of the conditions that must be satisfied in order to have excellent electrical conductivity. In the present invention, a surfactant was used to achieve individualization of carbon nanotubes, and the surfactant was transformed into an isoalloxazine derivative containing a saturated or unsaturated alkyl group having 3 to 20 carbon atoms in the side chain. A nanocomposite with a very improved electrical conductivity was completed by maximizing the chemistry and improving interfacial compatibility.

X is, for example, a butadienyl group, pentadienyl group, hexadienyl group, heptadienyl group, octadienyl group, dodecyl ( Dodecyl) group, tetradecyl (tetradecyl), hexadecyl (hexadecyl) group, octadecyl (octadecyl) or eicosyl (eicosyl) group may be.

The pentadienyl group can undergo an addition polymerization reaction in that there is a delocalized double bond, and based on this, the interfacial compatibility between the carbon nanotube and the polymer matrix can be improved in that it can covalently bond with the polymer matrix. It is preferable. In the case of a more general unsaturated alkyl group, it is preferable because it can covalently bond.

In the case of the saturated alkyl group, the carbon nanotubes can be well dispersed in the organic solvent by using methods such as ultrasonic grinding and ball milling, which are known in the past, and the saturated alkyl group exposed to the surface when the solvent is removed is the interface with the hydrophobic polymer matrix. It is very suitable for nanocomposite synthesis because it can increase the suitability.

The carbon nanotube coated with the isoalloxazine derivative may be included in an amount of 1 to 12% by weight based on the total weight of the polyamide-carbon nanotube nanocomposite. The carbon nanotubes coated with the isoalloxazine derivative are dispersed in the polyamide matrix within the above range, so that the electrical conductivity can be remarkably increased with excellent interfacial properties. If it is included in less than 1% by weight, the expected effect of improving electrical conductivity may be insufficient, and if it exceeds 12% by weight, mechanical strength including tensile strength of the polyamide-carbon nanotube nanocomposite is rapidly reduced. It is not desirable because it can.

More preferably, the carbon nanotube coated with the isoalloxazine derivative may be included in an amount of 3 to 10% by weight based on the total weight of the polyamide-carbon nanotube nanocomposite. The carbon nanotubes coated with the isoalloxazine derivative are preferably contained in an amount of 3 to 10% by weight in that electrical conductivity rapidly increases. As can be seen in the examples to be described later, in the above range, the polyamide-carbon nanotube nanocomposite showed an electrical conductivity of 100 S/m or more, which is the electricity seen in the previously reported polyamide-carbon nanotube nanocomposite. It corresponds to an electrical conductivity that is almost 10 times higher than the conductivity value.

The carbon nanotubes may be any one or a mixture of two or more selected from single-walled carbon nanotubes and multi-walled carbon nanotubes, among which the multi-walled carbon nanotubes are preferable in that they have more excellent electrical conductivity.

Another aspect of the present invention is to prepare a dispersion solution in which a surfactant and carbon nanotubes are mixed; Bonding a surfactant to the surface of the carbon nanotubes; Preparing a carbon nanotube coated with an isoalloxazine derivative by heat-treating the carbon nanotube to which the surfactant is bonded to the surface to transform the surfactant into an isoalloxazine derivative represented by the following Formula 1; And it provides a method for producing a polyamide-carbon nanotube nanocomposite comprising; and melt-extruding a mixture of the carbon nanotubes coated with the isoalloxazine derivative and the polyamide-based polymer resin.

[Formula 1]

In the above formula, R is hydrogen or alkyl having 1 to 6 carbon atoms, and R ₁ to R ₄ are each independently hydrogen, alkyl, hydroxy, halogen atom, halogenated alkyl group, carbonyl group, cyan group, alkoxy group, alkylthio, thio group, It is an allyl group, an aryl group, or a nitrogen heterocycle, and X is a C3-C20 saturated or unsaturated alkyl group. As described above in the part of the polyamide-carbon nanotube nanocomposite, in the method for preparing the polyamide-carbon nanotube nanocomposite of the present invention, a surfactant is coated on a carbon nanotube and then heat-treated to form a side chain of the surfactant. By modifying, the interfacial compatibility with the polyamide resin could be greatly improved while maintaining the dispersibility of the carbon nanotubes. A polyamide-nano composite having very high electrical conductivity could be prepared through improved dispersibility and interfacial compatibility.

The solvent of the dispersion solution may be water.

The bonding of the surfactant to the surface of the carbon nanotube may be performed using an ultrasonic wave, a ball mill, or a dispersion method using milling.

The surfactant may be any one or a mixture of two or more selected from FMN (flavin mononucleotide), FC12 (N-dodecyl flavin), FC16 (N-hexadecyl flavin), and FC20 (N-eicosyl flavin). The FMN forms N-pentadienyl side chains by heat treatment in the future and has very similar miscibility with polyamide, so it is preferable in that it can improve electrical conductivity by dispersing carbon nanotubes well in polyamide. Do.

The heat treatment may be performed for 1 to 4 hours in an air atmosphere of 300 to 600 °C. When the heat treatment is performed in an air atmosphere, an effect of forming a nanocomposite in which carbon nanotubes are well dispersed in a polymer matrix can be expected compared to a case where the heat treatment is not performed in an air atmosphere. The heat treatment may be performed at a temperature of 300 to 600 °C, preferably at 400 to 500 °C. If the heat treatment is performed at less than 300 ℃, there is a problem that the phosphoric acid group and the hydroxyl group of the side chain are not removed. If it exceeds 600 ℃, the isoalloxazine ring attached to the surface of the carbon nanotube is oxidized and may not be well dispersed in the polymer matrix It is not desirable because there is.

In addition, the heat treatment may be performed for 1 to 4 hours, preferably 90 to 150 minutes. When the heat treatment is performed for less than 1 hour, there is a problem that the phosphoric acid group and the hydroxyl group of the side chain are not sufficiently removed, and when it exceeds 4 hours, there may be a problem that the isoalloxazine ring attached to the surface of the carbon nanotube is oxidized.

The carbon nanotube coated with the isoalloxazine derivative may be included in an amount of 1 to 12% by weight based on the total weight of the polyamide-carbon nanotube nanocomposite. The effect according to the content of the carbon nanotube coated with the isoalloxazine derivative is the same as described above for the polyamide-carbon nanotube nanocomposite.

Although not explicitly described in the following Examples or Comparative Examples, etc., in the method of manufacturing a polyamide-carbon nanotube nanocomposite according to the present invention, a polyamide-carbon nanotube nanocomposite is prepared by varying various conditions of the method of manufacturing. Was prepared, and a film was prepared using each of the prepared polyamide-carbon nanotube nanocomposites. The surface of the prepared film was analyzed using SEM, and FT-IR analysis and electrical conductivity were measured.

식으로부터 계산되는 δ 값이 15 J^1/2/cm^3/2이상의 값을 가져, 폴리아미드와 유사한 혼화성을 가질 수 있었으며, 100 S/m 이상의 전기전도도를 가짐과 동시에 성형성이 우수하여 유려한 미관의 필름으로 제조하기 용이하였다. As a result, unlike other conditions and numerical ranges, when all of the following conditions are satisfied

Since the δ value calculated from the equation has a value of 15 J ^1/2 /cm ^3/2 or more, it can have similar miscibility with polyamide, and has an electrical conductivity of 100 S/m or more and has excellent moldability. It was easy to manufacture as a beautiful film.

(I) The step of bonding the surfactant to the surface of the carbon nanotube is to use a dispersion method using a ball mill (ii) X in Formula 1 is a pentadienyl group, (iii) a surfactant Is FMN (flavin mononucleotide), (iv) heat treatment is performed for 90 to 150 minutes in an air atmosphere of 400 to 500 ℃, (v) carbon nanotubes coated with isoalloxazine derivatives are polyamide-carbon nanotube nanocomposites Including 9 to 11% by weight based on the total weight, (vi) the solvent of the dispersion solution is water.

However, if any of the above conditions is not satisfied, the δ value does not reach 15 and falls sharply to less than 12, or the electrical conductivity has a value of 100 S/m or less, and the appearance is poor due to poor moldability. Or there was a problem that the film could not be manufactured at all.

Hereinafter, a preferred embodiment is presented to aid the understanding of the present invention. However, these examples are for describing the present invention in more detail, and the scope of the present invention is not limited thereto, and various changes and modifications are possible within the scope and spirit of the present invention. It will be self-evident to those who have knowledge.

Example. Preparation of PA-dFMN-MWNT nanocomposite

Flavin mononucleotide (FMN) containing an N-d-ribityl phosphate group was used as an aqueous surfactant to individualize MWNTs. MWNT (diameter: ca. 11 nm, length: <40 m, wall number: 10-15 layers) was decomposed using FMN, water, and ball mill method. First, an aqueous dispersion of MWNT and FMN was prepared using vibration ball milling of 50 Hz. In order to functionalize MWNT to FMN, 0.10 g of MWNT and 0.08 g of FMN were milled (Pulverisette 23 Fritsch, German) with 2%-v zirconia balls (diameter = 5 mm) in 3.0 mL water for 2 hours. The prepared slurry was vacuum filtered using a Büchner funnel and an aspirator (Eyela A-3S). The obtained black FMN-MWNT paper was washed several times with water to remove unbound FMN, and freeze-dried to prepare FMN-MWNT powder.

In this process, the aromatic isoalloxazine ring of FMN helically wraps around the MWNT, and the anionic repulsion of the radially distributed d-ribitylphosphate group caused the formation of an excellent colloidal dispersion of MWNT. Next, the FMN-MWNT powder was annealed in an air atmosphere at 450° C. for 2 hours to prepare dFMN-MWNT containing N-pentadienyl isoalloxazine. In such an air atmosphere, annealing partially transformed the d-ribitylphosphate group present in FMN into an N-pentadienyl group, and the isoalloxazine ring became almost inactive.

The PA-dFMN-MWNT nanocomposite was prepared by melt extrusion of a mixture of PA and dFMN-MWNT. For the nanocomposite containing 1 wt% dFMN-MWNT, PA-dFMN-MWNT-1, the nanocomposite containing 5 wt% PA-dFMN-MWNT-5, and the nanocomposite containing 10 wt% PA-dFMN Named -MWNT-10. Extrusion was performed at 250° C., about 30° C. higher than the melting point of PA, using a melt mixing method and a twin screw extruder. Next, a sheet having a thickness of 90-450 μm was prepared by a melt press. 1 is a schematic diagram of a method of manufacturing a nanocomposite according to an exemplary embodiment of the present invention, and FIG. 2 is an actual photograph of a nanocomposite sheet manufactured according to an exemplary embodiment of the present invention. As can be seen in FIG. 2, the color of the PA-dFMN-MWNT nanocomposite gradually turned to dark black as the MWNT content increased.

Experimental Example 1. Scanning Electron Microscopy (SEM)

The surfaces of the PA-dFMN-MWNT-1, PA-dFMN-MWNT-5, and PA-dFMN-MWNT-10 nanocomposites prepared from the above examples were analyzed by SEM. 3 is an SEM image of the surface of the PA-dFMN-MWNT nanocomposite prepared according to an embodiment of the present invention. 3a to c are PA-dFMN-MWNT-1, FIGS. 3d to f are PA-dFMN-MWNT-5, and FIGS. 3g to 3i are SEM analysis results of PA-dFMN-MWNT-10 at different magnifications. As can be seen in FIG. 3, a white area showed a non-uniform shape surrounded by a PA matrix showing a black background. In the enlarged magnification, it was confirmed that the white area was MWNT having a diameter of 100 nm. Since the diameter of MWNT is 11 nm, it was confirmed that a 45 nm thick PA layer coated the MWNT surface during melt extrusion, from which the N-pentadienyl side chain of FMN was good between the PA matrix and dFMN-MWNT. It was confirmed that conjugation was induced. In the sample with a higher MWNT content, it was confirmed that the white area was gradually enlarged.

Experimental Example 2. Measurement of electrical conductivity

The electrical conductivity of the PA-dFMN-MWNT nanocomposite prepared in the above example was measured. 4 is a result of measuring the electrical conductivity of the nanocomposite prepared according to an embodiment of the present invention. 4A is an image of a circuit including a 4.5 V AA battery connected in series with an LED, and PA-dFMN-MWNT-10 used as a resistor, and the inset is a circuit diagram. Figure 4b is a photo of the LED in the absence of PA, PA-dFMN-MWNT-3, -5, -10 and nanocomposite. Figure 4c is a graph measuring the electrical conductivity of PA-dFMN-MWNT-3, -5 and -10.

As can be seen in FIG. 4, the conductivity (σ) value of PA-dFMN-MWNT increased as the MWNT content increased. As a result of observing the LED by connecting PA-dFMN-MWNT in series to an LED connected to a 4.5 V AA battery (FIG. 4A), it was confirmed that PA-dFMN-MWNT-10 acts as a good conductor. In FIG. 4B, it was confirmed that the intensity of light emitted from the LED increased as the content of MWNT increased. In addition, in the electrical conductivity (σ) measurement, the σ values of PA and PA-dFMN-MWNT-1 were lower than the detection limit of the instrument (10 ^-2 S/m), but the conductivity value increased as the MWNT content increased, resulting in PA-dFMN- The maximum was reached in MWNT-10. In particular, the σ value of PA-dFMN-MWNT-10 was almost 10 times higher than that of PA containing MWNT nanocomposite reported so far.

Experimental Example 3. Raman spectrum

The high conductivity value observed in the PA-dFMN-MWNT nanocomposite is due to the formation of very low levels of defects in the manufacturing process. 5 is a Raman spectrum analysis result of a nanocomposite prepared according to an embodiment of the present invention. Black represents MWNT, red represents dFMN-MWNT, blue represents the Raman spectrum result of PA-dFMN-MWNT-10, and as can be seen in FIG. 5, D, G and 2D at 1350, 1600, 2700 cm ^-1 respectively Included the band.

In general, when a defect occurs in MWNT, the strength of the graphitic D band of about 1350 cm ^-1 increases. In FIG. 5, it was confirmed that the intensity of the D band in the Raman spectrum of dFMN-MWNT and PA-dFMN-MWNT-10 did not increase significantly compared to MWNT. Therefore, it was found that the ball milling and melt extrusion process did not cause any defects.

Experimental Example 4. Mechanical strength measurement

Next, tensile strength and break elongation were evaluated to measure the mechanical strength of the PA-dFMN-MWNT nanocomposite prepared in the above example. To this end, the nanocomposite was prepared as a rectangular sample, loaded into an Instron device, and subjected to a stress-strain curve analysis.

6 is a result of measuring the mechanical strength of the nanocomposite according to an embodiment of the present invention. 6A is a stress-strain curve of a nanocomposite according to an embodiment of the present invention, and FIG. 6B is a result of measuring tensile strength and elongation at break of the nanocomposite according to an embodiment of the present invention.

As can be seen in Figure 6a, PA alone had a value of 45 MPa, which is well known as the tensile strength of PA, and had a value gradually decreased as the content of MWNT increased, but when 1 wt% of MWNT was included PA-dFMN-MWNT-10 containing 30-31 MPa, 10 wt% decreased to 12 MPa.

In addition, as can be seen in Figure 6b, PA alone showed an elongation of 21%, but the nanocomposite including MWNT decreased to 2% as the MWNT content increased.

Experimental Example 5. FT-IR analysis

The cause of the decrease in mechanical strength observed in Example 4 was confirmed through FT-IR analysis. 7 is an FT-IR analysis result of a nanocomposite according to an embodiment of the present invention. Table 1 below is a band analysis of the FT-IR spectrum of PA.

frequency, cm ^-1 Description 3436 “Free” N-H stretch 3325 hydrogen-bonded N-H stretch 2925 asymmetric CH ₂ stretch 2862 symmetric CH ₂ stretch 1639 amide I mode 1551 amide II mode 1261 amide III mode 728 amide V mode

As can be seen in Fig. 7 and Table 1, the PA spectrum composed of amide and (CH ₂ ) ₅ moieties is each “free” NH stretching, hydrogen bonding NH stretching, and 3436, 3325, 1639, 1551 assigned to the amide. , 1261 and 728 cm ^-1 . Strong asymmetric and symmetric CH stretching bands occurred at 2925 and 2862 cm ^-1 , respectively. In particular, as the MWNT content of the dFMN-MWNT nanocomposite increased, the free NH band in the spectrum increased and the hydrogen-bonded NH band decreased. In addition, as the MWNT content of the nanocomposite increased, the amide 1 band (1639 cm ^-1 ) corresponding to the free amide drastically decreased. Through this, it was found that when dFMN-MWNT was present, hydrogen bonding was reduced in the PA chain, and in particular, when the nanocomposite containing PA contained only MWNT, the mechanical strength was improved. This contrasting feature was found that dFMN, particularly the uracil moiety present in the isoalloxazine group, competedly participates in the hydrogen bonding interactions with the PA matrix, and this interaction reduces tensile strength and elongation. Could

식을 이용하였으며, 상기 식에서 E_coh와 V는 각각 응집에너지(J/mol)과 몰부피(cm³/mol)를 나타낸다. 이를 바탕으로 dFMN-MWNT에 존재하는 펜타디에닐 구조의 δ는 15.8 J^1/2/cm^3/2로 측정되었으며, 이는 PA의 값(i.e., 25.4 J^1/2/cm^3/2)과 유사하였다. 그러므로, dFMN-MWNT 유도된 나노 복합체에서 PA 매트릭스와 dFMN-MWNT의 높은 수준의 혼화성으로 인하여 기계적 강도의 감소 및 전기 전도도의 증가를 이루는 것을 알 수 있었다.It was confirmed that the dramatic increase in the electrical properties of PA-dFMN-MWNT was a result of improved miscibility between PA and dFMN-MWNT due to the hydrophobicity of the N-pentadienyl side chain present in dFMN-MWNT. To prove this,

The equation was used, where E _coh and V represent the cohesive energy (J/mol) and the molar volume (cm ³ /mol), respectively. Based on this, the δ of the pentadienyl structure present in dFMN-MWNT was measured as 15.8 J ^1/2 /cm ^3/2 , which is similar to the value of PA (ie, 25.4 J ^1/2 /cm ^3/2 ). I did. Therefore, it was found that in the dFMN-MWNT-derived nanocomposite, the mechanical strength decreased and the electrical conductivity increased due to the high level of miscibility between the PA matrix and dFMN-MWNT.

Accordingly, the polyamide-carbon nanotube nanocomposite of the present invention has excellent dispersibility of the carbon nanotubes and improved interfacial compatibility, thereby having very high electrical conductivity.

The above-described Examples and Comparative Examples are examples for explaining the present invention, and the present invention is not limited thereto. Since those of ordinary skill in the art to which the present invention pertains will be able to implement the present invention by various modifications therefrom, the technical protection scope of the present invention should be determined by the appended claims.

Claims (8)

Polyamide polymer resin; And
Including; carbon nanotubes dispersed in the polyamide-based polymer resin and coated with an isoalloxazine derivative represented by the following formula (1),
The carbon nanotubes coated with the isoalloxazine derivative are poly(a) wherein a surfactant is bonded to the surface of the carbon nanotube, and the carbon nanotubes to which the surfactant is bonded to the surface are heat-treated to transform the surfactant into an isoalloxazine derivative Amide-carbon nanotube nanocomposite:
[Formula 1]

In the above formula, R is hydrogen or alkyl having 1 to 6 carbon atoms, and R ₁ to R ₄ are each independently hydrogen, alkyl, hydroxy, halogen atom, halogenated alkyl group, carbonyl group, cyan group, alkoxy group, alkylthio, thio group, It is an allyl group, an aryl group, or a nitrogen heterocycle, and X is a C3-C20 saturated or unsaturated alkyl group.
The method of claim 1,
The carbon nanotube coated with the isoalloxazine derivative is a polyamide-carbon nanotube nanocomposite containing 1 to 12% by weight based on the total weight of the polyamide-carbon nanotube nanocomposite.

The method of claim 1,
The carbon nanotube coated with the isoalloxazine derivative contains 3 to 10% by weight based on the total weight of the polyamide-carbon nanotube nanocomposite,
The polyamide-carbon nanotube nanocomposite having an electrical conductivity of 100 S/m or more.
Preparing a dispersion solution in which a surfactant and carbon nanotubes are mixed;
Bonding a surfactant to the surface of the carbon nanotubes;
Preparing a carbon nanotube coated with an isoalloxazine derivative by heat-treating the carbon nanotube to which the surfactant is bonded to the surface to transform the surfactant into an isoalloxazine derivative represented by the following Formula 1; And
A method for producing a polyamide-carbon nanotube nanocomposite comprising: melt-extruding a mixture of the carbon nanotubes coated with the isoalloxazine derivative and a polyamide-based polymer resin:
[Formula 1]

In the above formula, R is hydrogen or alkyl having 1 to 6 carbon atoms, and R ₁ to R ₄ are each independently hydrogen, alkyl, hydroxy, halogen atom, halogenated alkyl group, carbonyl group, cyan group, alkoxy group, alkylthio, thio group, It is an allyl group, an aryl group, or a nitrogen heterocycle, and X is a C3-C20 saturated or unsaturated alkyl group.
The method of claim 4,
The step of bonding the surfactant to the surface of the carbon nanotubes is a method of manufacturing a polyamide-carbon nanotube nanocomposite using a dispersion method using ultrasonic waves, a ball mill, or milling.
The method of claim 4,
The surfactant is any one or a mixture of two or more selected from FMN (flavin mononucleotide), FC12 (N-dodecyl flavin), FC16 (N-hexadecyl flavin), and FC20 (N-eicosyl flavin) polyamide-carbon nanotube nano Method for producing the composite.
The method of claim 4,
The heat treatment is performed for 1 to 4 hours in an air atmosphere of 300 to 600° C. A method for producing a polyamide-carbon nanotube nanocomposite.
The method of claim 4,
The method for producing a polyamide-carbon nanotube nanocomposite containing 1 to 12% by weight of the total weight of the polyamide-carbon nanotube nanocomposite in the carbon nanotube coated with the isoalloxazine derivative.

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