Graphene-containing composite material, preparation method and use thereof

Abstract

A graphene-containing composite material comprises components of a composite functional material with a double-conductive channel and a polymer matrix. The composite functional material with a double-conductive channel is sulfonated graphene surface grafted conductive polymer poly-3,4-(ethylenedioxythiophene). The composite functional material with a double-conductive channel and the graphene-containing composite material can be used for preparing a piezoresistance response material or an antistatic or electromagnetic shielding material and the like, and have excellent piezoresistance response, piezoresistance repeatability and electromagnetic shielding effect. The present invention is simple and easy to operate, can be used in large scale production, has excellent piezoresistance performance and very sensitive piezoresistance response, with the percolation threshold being only 0.5 wt %; not only the original performance of the polymer can be maintained, but also an unstable conductive network system can be formed, which facilitates the improvement of the sensitivity of the piezoresistance response.

Claims

1. A functional composite material with a double-conductive channel, comprising a sulfonated graphene whose surface is grafted with a conductive poly(3,4-ethylenedioxythiophene) (PEDOT) polymer, of the following general formula (1): ##STR00002## where, n represents the degree of polymerization and is an integer in the range of 100 to 8000.

2. The functional composite material with a double-conductive channel according to claim 1, wherein the sulfonated graphene and the conductive PEDOT are present in a weight ratio of 1:1 to 1:100.

3. The functional composite material with a double-conductive channel according to claim 2, wherein the weight ratio of the sulfonated graphene to the conductive PEDOT is from 1:3 to 1:10.

4. The functional composite material with a double-conductive channel according to claim 1, wherein the sulfonated graphene is obtained by grafting 4-aminobenzenesulfonic acid or a derivate thereof to graphene with a graft ratio of 1% to 80%.

5. A graphene-containing composite material, comprising constituents including a functional composite material with a double-conductive channel according to claim 1 and a polymer matrix.

6. The graphene-containing composite material according to claim 5, wherein the functional composite material with a double-conductive channel and the polymer matrix are present in a weight ratio of 0.1:100 to 20:100.

7. The graphene-containing composite material according to claim 5, wherein the polymer matrix is selected from a polyolefin-based polymer, a polyester-based polymer, a rubber-based polymer, polyoxymethylene, polysulfone and polylactic acid.

8. The graphene-containing composite material according to claim 7, wherein the polyolefin-based polymer is polyethylene, polypropylene, polystyrene or polyvinylidene chloride, wherein the polyester-based polymer is polyethylene terephthalate or polycarbonate, and wherein the rubber-based polymer is silicone rubber.

9. A method of preparing a functional composite material with a double-conductive channel according to claim 1, comprising the steps of: 1) dissolving sulfonated graphene in water, thereby obtaining a sulfonated graphene solution with a concentration of 1 mg/mL to 20 mg/mL; 2) adding 3,4-ethylenedioxythiophene (EDOT); adding a 5-30 wt. % sodium persulfate (Na.sub.2S.sub.2O.sub.8) solution such that the weight of the added sodium persulfate accounts for 10-60% of that of the sulfonated graphene; 4) gathering, after a reaction period of 4-8 hours at room temperature, a reaction product comprising a PEDOT/graphene composite paste; and 5) curing the PEDOT/graphene functional composite paste to obtain the functional composite material with a double-conductive channel.

10. The method according to claim 9, wherein the EDOT and the sulfonated graphene are present in a weight ratio of 1:1 to 100:1.

11. The method according to claim 9, further comprising the step of: blending the PEDOT/graphene functional composite paste with a polymer matrix prior to said curing.

12. The method according to claim 11, wherein said blending comprises melt blending or solution bending.

13. The method according to claim 9, further comprising the step of coating the PEDOT/graphene functional composite paste on a substrate prior to said curing, wherein said curing is carried out in a vacuum at a temperature of 40-80 C. to obtain a PEDOT/graphene functional composite sheet having a thickness of 0.1 m-10 mm from the substrate, and wherein the substrate is made of a polymer, metal or fabric.

14. A piezoresistive material comprising the functional composite material with a double-conductive channel according to claim 1.

15. An antistatic material comprising the functional composite material with a double-conductive channel according to claim 1.

16. An electromagnetic shielding material comprising the functional composite material with a double-conductive channel according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a microscopic image of sulfonated graphene.

(2) FIG. 2 is an infrared spectrum of a PEDOT/graphene functional composite material.

(3) FIG. 3 is an SEM image of a PEDOT/graphene functional composite material.

(4) FIG. 4 is a diagram showing resistivity vs. functional component content profiles of conductive polymer/graphene/polymer functional composite materials according to Examples 4-6.

(5) FIG. 5 illustrates variation of resistivity of the conductive polymer/graphene/polymer functional composite material of Example 4 with pressure.

DETAILED DESCRIPTION

(6) The present invention will be described in greater detail with reference to several specific embodiments which are presented for illustration only without limiting the invention in any sense. These embodiments are examples of practical use that will be readily understood and validated by those skilled in the art. Any changes made in light of the present invention are considered as not essentially deviating from the scope of the invention.

EXAMPLE 1

(7) 1) Preparation of Sulfonated Graphene

(8) Carboxylated graphene was dispersed in deionized water and the dispersion was facilitated by ultrasonic waves for 2 hours, so that a 10 mg/mL carboxylated graphene solution was prepared for subsequent use.

(9) 4-Aminobenzenesulfonic acid was dissolved in deionized water to prepare a 20 mg/mL solution for subsequent use.

(10) The two solutions obtained above were mixed together in a volume ratio of 2:3, followed by addition thereto of 1-3 drops of dibutyltin dilaurate as a catalyst. The mixture was then heated with reflux at 95 C. to allow reaction for 10 hours. The system was then cooled to 90 C. and added with hydrazine hydrate, followed by reaction for 2 hours at the temperature that was maintained. A ratio of the amount of the added hydrazine hydrate to that of the carboxylated graphene was 1.0 mL:0.8 g. As a result, sulfonated graphene was obtained, and its morphology and surface groups were characterized, with the results shown in FIG. 1. As can be seen from this figure, the sulfonated graphene appeared as very thin sheets with a grafting ratio of 40%.

(11) 2) Preparation of Conductive Polymer/Functionalized Graphene Composite Material

(12) At first, 100 mg of the sulfonated graphene resulting from step 1) was weighed and dissolved in 100 mL of deionized water, resulting in a 1 mg/mL sulfonated graphene solution which was then added with 5 g of 3,4-ethylenedioxythiophene (EDOT) as a monomer and a certain amount of a sodium persulfate (Na.sub.2S.sub.2O.sub.8) solution as an initiator. The mixed solution was then maintained at room temperature to allow reaction for 4 hours. After spin distillation and concentration, a poly (3,4-ethylenedioxythiophene) (PEDOT)/graphene composite was obtained in the form of a paste, whose infrared spectrum was shown in FIG. 2. In the composite, sulfonated graphene and PEDOT were present in a mass ratio of 3:1, and n=400.

(13) In FIG. 2, there are a characteristic peak of sulfonic acid groups at 1190 cm.sup.1, a peak at 1228 cm.sup.1 resulting from the stretch vibrations of COC bonds, most of which are from EDOT, a characteristic peak at 1540 cm.sup.1 for CN in-plane bending, and a peak around 1720 cm.sup.1 indicative of the stretch vibrations of CO bonds in ester groups.

(14) Surface morphology of the composite material was also characterized and the results were summarized in FIG. 3. The paste can be directly cured to form a PEDOT/graphene functional composite material, or combined with other polymers to prepare other functional composite materials.

EXAMPLE 2

(15) 1) Preparation of Sulfonated Graphene

(16) First of all, a certain amount of carboxylated graphene was weighed and dispersed in deionized water and the dispersion was facilitated by ultrasonic waves for 4 hours, so that a 10 mg/mL carboxylated graphene solution was prepared for subsequent use. A certain amount of a 4-aminobenzenesulfonic acid derivative R-1 was dissolved in deionized water (heating might be optionally carried out to facilitate the dissolution) to prepare a 20 mg/mL solution for subsequent use. The two solutions obtained above were mixed together in a volume ratio of 2:3, followed by addition thereto of 1-3 drops of dibutyltin dilaurate as a catalyst. The mixture was then heated with reflux at 95 C. to allow reaction for 10 hours. The system was then cooled to 90 C. and added with a certain amount of hydrazine hydrate, followed by reaction for 2 hours at the temperature that was maintained, so that sulfonated graphene was obtained. A ratio of the amount of the added hydrazine hydrate to that of the carboxylated graphene was 1.2 mL:1 g. A graft ratio of 60% was achieved.

(17) 2) Preparation of Conductive Polymer-Functionalized Graphene Composite Material 300 mg of the sulfonated graphene resulting from step 1) was first weighed and dissolved 100 mL of deionized water, resulting in a 3 mg/mL sulfonated graphene solution which was then added with 50 g of EDOT as a monomer and a certain amount of a sodium persulfate (Na.sub.2S.sub.2O.sub.8) solution. The mixed solution was then maintained at room temperature to allow reaction for 6 hours. After spin distillation and concentration, a PEDOT/graphene composite was obtained in the form of a paste, which could be directly cured to form a PEDOT/graphene functional composite material, or combined with other polymers to prepare other functional composite materials. In the composite, sulfonated graphene and PEDOT were present in a mass ratio of 6:1, and n=1000.

EXAMPLE 3

(18) 1) Preparation of Sulfonated Graphene

(19) First of all, a certain amount of carboxylated graphene was weighed and dispersed in deionized water and the dispersion was facilitated by ultrasonic waves for 6 hours, so that a 10 mg/mL carboxylated graphene solution was prepared for subsequent use. A certain amount of a

(20) 4-aminobenzenesulfonic acid derivative R-2 was then dissolved in deionized water (heating might be optionally carried out to facilitate the dissolution) to prepare a 20 mg/mL solution for subsequent use. The two solutions obtained above were mixed together in a volume ratio of 2:3, followed by addition thereto of 1-3 drops of dibutyltin dilaurate as a catalyst. The mixture was then heated with reflux at 95 C. to allow reaction for 10 hours. The system was then cooled to 90 C. and added with a certain amount of hydrazine hydrate, followed by reaction for 2 hours at the temperature that was maintained, so that sulfonated graphene was obtained. A ratio of the amount of the added hydrazine hydrate to that of the carboxylated graphene was 1.5 mL:1 g. A graft ratio of 75% was achieved.

(21) 2) Preparation of Conductive Polymer-Functionalized Graphene Composite Material

(22) At first, 500 mg of the sulfonated graphene resulting from step 1) was weighed and dissolved 100 mL of deionized water, resulting in a 5 mg/mL sulfonated graphene solution which was then added with 100 g of EDOT as a monomer and a certain amount of a sodium persulfate (Na.sub.2S.sub.2O.sub.8) solution. The mixed solution was then maintained at room temperature to allow reaction for 8 hours. After spin distillation and concentration, a PEDOT/graphene composite was obtained in the form of a paste, which could be directly cured to form a PEDOT/graphene functional composite material, or combined with other polymers to prepare other functional composite materials. In the composite, sulfonated graphene and PEDOT were present in a mass ratio of 10:1, and n=6000.

EXAMPLE 4

(23) Preparation of Conductive Polymer/Graphene/Polymer Composite Material

(24) A conductive polymer/functionalized graphene/polymer functional composite material was prepared by blending 1 g of the concentrated paste, prepared as in Example 1, with 100 g of polyurethane (solution blending) so that a solid content of 0.1:100 by weight was obtained, and then drying and curing the blend. Thereafter, a series of tests were performed in conjunction with Examples 5 and 6 to analyze the dependence of conductivity on the content of the functional filler, as shown in FIG. 4.

(25) Analysis was further conducted on the responsivity of the functional composite material to pressure, as shown FIG. 5.

(26) The results showed that, with the solid content of the PEDOT/graphene composite functioning as the functional filler increasing, the volume resistivity of the composite material decreased abruptly to a percolation threshold at a solid content of 0.5 wt % and then evolved smoothly without much changes despite further increase of the filler content. In addition, as shown in FIG. 5, as the pressure increased, resistivity increased with increasing linearity, indicating very good electrical properties and piezoresistive response characteristics of the prepared functional composite material and hence applicability thereof to the fields of sensing materials and electromagnetic shielding.

EXAMPLE 5

(27) Preparation of Conductive Polymer/Graphene/Polymer Composite Material A conductive polymer/functionalized graphene/polymer functional composite material was prepared by blending 10 g of the concentrated paste, prepared as in Example 2, with 100 g of natural rubber (direct blending) so that a solid content of 1:100 by weight was obtained, and then drying and curing the blend.

EXAMPLE 6

(28) Preparation of Conductive Polymer/Graphene/Polymer Composite Material A conductive polymer/functionalized graphene/polymer functional composite material was prepared by blending 20 g of the concentrated paste, prepared as in Example 3, with 100 g of polystyrene (melt blending) so that a solid content of 2:100 by weight was obtained, and then drying and curing the blend.

EXAMPLE 7

(29) Preparation of Conductive Polymer/Graphene/Polymer Composite Material

(30) 1 g of the concentrated paste, prepared as in Example 3, was coated on the surface of a polymer substrate (not limited thereto, as a metal, inorganic, fabric or the like substrate might be also suitable) to form a functional composite sheet. In the present example, polycarbonate was selected as the substrated. The coating thickness (0.1 m-10 m) might be determined as practically needed (i.e., not limited to the aforementioned thickness). The functional composite sheet might be of a structure of B/A, B/A/B, A/B/A, etc., where A denoted a functional film, and B represented a polymer film. Finally, it is subjected to drying and curing to result in a conductive polymer/functionalized graphene/polymer functional composite material.