TW201305047A - Surface-modified graphene - Google Patents

Abstract

A surface-modified graphene comprises a graphene powder and at least one surface modification layer which comprises a surface modifier including at least two functional groups respectively formed at two ends of the surface modifier. One of the two functional groups is chemically bonded to the organic functional group on the surface of the graphene powder, and the other of the two functional groups is formed on the surface of the surface-modified graphene, wherein the surface modifier comprises at least one of a coupling agent, a fatty acid and a resin. Therefore, the surface-modified graphene powder can increase the dispersivity of the graphene powder in the solvent and increase the affinity between the graphene powder with organic polymer. In addition, the composite material can be made sturdier to provide wide applicability thereto.

Description

Surface modified graphene

The present invention provides a surface-modified graphene, and more particularly to a surface-modified graphene which changes the surface characteristics of graphene powder through a surface modifier.

Single-layer graphite, also known as graphene, is a lattice structure in which a single layer of carbon atoms is closely packed into a two-dimensional honeycomb with graphite bonds (sp ² ), so there is only one carbon atom thickness, graphite bond. The composite bond between the covalent bond and the metal bond can be said to be the natural fit of the insulator and the conductor. In 2004, Andre Geim and Konstantin Novoselov of the University of Manchester in the United Kingdom successfully used tape to strip graphite, which confirmed that a single layer of graphene could be obtained and won the 2010 Nobel Prize in Physics.

Graphene is currently the thinnest and hardest material in the world. Its thermal conductivity is higher than that of carbon nanotubes and diamond. Its electron mobility is higher than that of carbon nanotubes or germanium crystals at room temperature, and its resistivity is lower than that of copper or silver. It is currently the world's smallest resistivity material. Graphene and carbon nanotubes have the advantages of high flexibility and low reflectivity in transparent electrodes. They are currently the first choice for soft electronic materials. However, the coating of graphene dispersion is better than the dispersion of carbon nanotubes. It is much more difficult, graphene is very easy to aggregate and stack in nature, and it is a technical difficulty to obtain a highly uniform and single-layer graphene film to avoid uneven stacking of graphene sheets with each other, but still make the sheets in contact with each other.

U.S. Patent No. 20110049437 uniformly blends graphene with a polymer binder, and can be applied to the surface of the substrate as a coating to change the surface characteristics of the substrate, especially to improve its conductivity. However, if the surface of the graphene is not sufficiently compatible with the binder, the two are not easily mixed, which will make the application less effective.

U.S. Patent No. 20110117955 discloses that graphene is coated on the surface of an epoxy resin hardener, and when the hardener is hardened by mixing with an epoxy resin, the thermal conductivity of the epoxy resin can be increased. Similar to the above-mentioned U.S. Patent No. 20110049437, the key is the affinity between the graphene and the organic polymer material, and when the joint between the graphene material and the polymer material is good, the characteristics of the composite material can be exerted.

U.S. Patent No. 20100178464 etches graphene edges and attaches organic functional groups such as -COOH, -C=O, etc. to the edges of the etch to improve the surface properties of the graphene. However, the etching method is complicated and costly. There is also concern about the bonding of the selected organic functional groups to the graphene surface.

The main object of the present invention is to provide a surface-modified graphene comprising a graphene powder and at least one surface modifying layer, the at least one surface modifying layer comprising a surface modifying agent, the surface modifying agent comprising at least a difunctional group respectively located at two ends of the surface modifying agent, the at least difunctional one functional group chemically bonding with an organic functional group on the surface of the graphene powder, and the other functional group of the at least difunctional group forms a surface The surface characteristics of the modified graphene, wherein the surface modifier comprises at least one of a coupling agent, a fatty acid, and a resin.

The coupling agent has a structure of M _x (R) _y (R') _z , wherein M is a metal element, R is a hydrophilic functional group, R' is a lipophilic functional group, and M is selected from aluminum, titanium, zirconium or hafnium. , R is selected from the group consisting of an alkoxy group, a carbonyl group, a carboxyl group, a decyloxy group, a decylamino group, an alkoxy group or an alkyloxy group, and the R' is selected from a vinyl group, a fatty alkylene group, a styryl group, a methyl group. Propylene methoxy, propylene oxime, aliphatic amino group, chloropropyl group, aliphatic thiol group, aliphatic thiol group, isocyanate group, aliphatic urea group, aliphatic carboxy group, aliphatic hydroxy group, ring a hexane group, a phenyl group, a arylmethyl sulfonyl group, an ethyl fluorenyl group or a benzamidine group, the fatty acid is selected from the group consisting of stearic acid or oleic acid, and the resin is selected from the group consisting of an epoxy resin, a polyurethane resin, and an anthracene resin. , phenol resin or polyester resin.

The surface modifier is between 0.1 and 10.0% by weight of the weight of the surface modified graphene.

The at least one surface modifying layer comprises a first surface modifying layer and a second surface modifying layer, the first surface modifying layer is a coupling agent layer, and the second surface modifying layer is a resin layer.

The at least one surface modifying layer comprises a first surface modifying layer, a second surface modifying layer and a third surface modifying layer, the first surface modifying layer is a coupling agent layer, and the second surface is modified. The layer is a resin layer, and the third surface modifying layer is a coupling agent layer.

Therefore, the surface-modified graphene powder of the present invention can improve the dispersibility of the graphene powder in a solvent, and can also improve the affinity between the graphene powder and the organic polymer, and further, by utilizing chemistry The method of modifying the structure or properties of graphene can make some "super substances" which are as thin, flexible and light as graphene more robust, and make it more widely applicable, for example, to prepare conductive polymers, or Can be used to manufacture satellites, airplanes and cars.

The embodiments of the present invention will be described in more detail below with reference to the drawings and the <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt;

The invention discloses a surface-modified graphene comprising a graphene powder and at least one surface modifying layer, the at least one surface modifying layer comprising a surface modifying agent. The surface modifying agent comprises at least a difunctional group respectively located at both ends of the surface modifying agent, the at least difunctional one functional group chemically bonding with the residual organic functional group on the surface of the graphene powder, the at least difunctional group An additional functional group forms the surface characteristics of the surface modified graphene.

Thus, the surface characteristics of the graphene powder are changed, so that the graphene powder can be uniformly dispersed in the solvent, or the degree of binding of the graphene powder to the organic polymer can be improved, which is beneficial to the subsequent widespread application of graphene. For example, it is a transparent conductive electrode, a heat conductive material, a super capacitor, or the like.

The surface modifier includes at least one of a coupling agent, a fatty acid, and a resin.

A coupling agent is often used in plastic compounding to improve the interfacial properties of synthetic resins and inorganic fillers or reinforcing materials. It can reduce the overall viscosity of the system during plastic processing and promote the dispersion of inorganic fillers in organic resins. Improve the mechanical strength and electrical properties of the product and increase the ability of the product to resist environmental factors. The coupling agent generally consists of two parts, one part is an inactive inorganic group, which can be bonded to the inorganic filler, and the other part is an organophilic group, which can react with the organic resin. Common coupling agents are decanes, titanates, zirconates, aluminum zirconates, aluminates, and chromates, of which decanes are most common.

The coupling agent of the present invention has the structure M _x (R) _y (R') _z , wherein M is a metal element, R is a hydrophilic functional group, and R' is a lipophilic functional group, wherein 0 ≦ x ≦ 6 , 1≦y≦20, and 1≦z≦20.

The M system of the coupling agent of the present invention is selected from one of aluminum, titanium, zirconium and hafnium.

One end of R of the coupling agent of the present invention is bonded to M, and R can be hydrolyzed to produce a hydrophilic functional group corresponding to the other end to chemically bond with the surface of the graphene powder, and R is selected from the group consisting of an alkoxy group and a carbonyl group. One of a carboxyl group, a decyloxy group, a decylamino group, an alkoxy group, and an alkyloxy group.

The R' of the coupling agent of the present invention is selected from the group consisting of vinyl, aliphatic alkylene oxide, styryl, methacryloxy, propyleneoxy, aliphatic, chloropropyl, aliphatic, thiol , a fatty thiol group, an isocyanate group, a fatty urea group, a fatty carboxy group, a fatty hydroxy group, a cyclohexane group, a phenyl group, a fatty methoxymethyl group, an ethyl fluorenyl group, and a benzamidine group. One. One end of R' is bonded to M and the other end is permeable to the functional groups of different natures described above, so that the surface-modified graphene surface is different from the pure graphene powder, and is particularly easy to disperse in the organic vehicle or The organic polymer reaction, when it is required to be blended with different organic polymers, is an optional affinity coupling agent for surface modification of pure graphene powder to cause chemical bonding between the two.

The first figure is a schematic diagram of a surface-modified graphene according to an embodiment of the present invention, using a coupling agent as a surface modifier. As shown in the first figure, (A) represents pure graphene powder, which has some residual organic functional groups, and (B) represents surface-modified graphene, using M _x (R) _y (R The coupling agent of the structure of _z ) is chemically bonded to the surface of the graphene powder by the hydrophilic functional group R, and the surface property of the surface-modified graphene is formed by the lipophilic functional group R'.

The surface modifier of the present invention may be selected from a high carbon number fatty acid, which also has a difunctional group having a relatively two terminal group, and a monofunctional group can react with the surface of the graphene powder while the other functional group is formed differently from the pure graphite. The surface characteristic of the olefin powder, the high carbon number fatty acid being selected from one of stearic acid and oleic acid.

The surface modifier of the present invention may be selected from a resin. Since the resin has various functional groups, it can provide surface characteristics different from those of the pure graphene powder, and the resin is selected from the group consisting of epoxy resin, polyurethane resin, and ruthenium. One of resin, phenol resin and polyester resin.

The surface modifier of the present invention comprises between 0.02 and 20.0% by weight of the surface modified graphene, preferably between 0.1 and 10.0% by weight.

The at least one surface modifying layer of the present invention comprises a first surface modifying layer and a second surface modifying layer, wherein the first surface modifying layer is a coupling agent layer, and the second surface modifying layer is a Resin layer.

The at least one surface modifying layer of the present invention comprises a first surface modifying layer, a second surface modifying layer and a third surface modifying layer, wherein the first surface modifying layer is a coupling agent layer, The second surface modifying layer is a resin layer, and the third surface modifying layer is a coupling agent layer.

Regarding the surface modifier described above, several examples which can be applied to the present invention are listed below.

Example 1 firstly carried out surface analysis on the pure graphene powder after synthesis, and Annex I is a TEM image, showing that pure graphene is a very thin sheet-like structure with a surface area of 430 m ² /g and an oxygen content of 1.3 wt%; The second is the carbon element test result of XPS. The results show that there are still a small amount of carbon oxide or hydrocarbon functional groups on the graphene powder surface.

Example 2 uses a coupling agent, 3-Aminopropyl triethoxysilane, as a surface modifier, and its structure is Si(C ₃ H ₆ N)(C ₂ H ₅ O) ₃ , and the embodiment is a surface modifier. A mixed solution of ethanol and water is added, and then the graphene powder is added for mixing and stirring. Finally, the powder is taken out by suction filtration and heated and dried in an oven to obtain a surface-modified graphene powder. Annex III is the modified TEM image of graphene. It shows that there is another film on the surface of graphene powder, which may be the surface modification agent. The EDS analysis can be performed by the circle of Annex III. The Si element signal as shown in Annex IV is tested, and the surface modifier is present on the surface of the graphene powder. The fifth is the XPS image of the modified graphene powder. The graphene powder can be seen from the figure. Signals of bismuth and nitrogen appear on the surface, and a signal different from pure graphene powder is also shown on the carbon map, which proves that the surface modifier is coated on the surface of the graphene powder.

In Example 3, a coupling agent, Titanium n-butoxide, was used as a surface modifier, and its structure was Ti(C ₄ H ₉ O) ₄ . The embodiment was to add a surface modifier to an isopropanol solvent. Then, the graphene powder is further added for mixing and stirring, and finally the powder is taken out by suction filtration and heated and dried in an oven to obtain a surface-modified graphene powder. Annex VI is the XPS image of the modified graphene powder. From the figure, the signal of titanium on the surface of the graphene powder can be seen, which proves that the surface modifier is coated on the surface of the graphene powder.

Example 4 uses an epoxy resin (cresol novolac epoxy resin) as a surface modifier, and its structure is as shown in the second figure. The embodiment is that the surface modifier is completely dissolved in an acetone solvent, and then the graphene powder is added. The mixture is stirred, and finally the powder is taken out by suction filtration and dried by heating in an oven to obtain a surface-modified graphene powder.

In the example 5, the graphene powder modified by the surface of the coupling agent aminooxane was used as the starting material, and the epoxy resin was completely dissolved in the acetone solvent, and then the surface of the oxirane was modified and stirred. The powder is removed by suction filtration and dried by heating in an oven to obtain a surface-modified graphene powder.

Therefore, the surface-modified graphene powder of the present invention is mainly characterized in that it can improve the dispersibility of the graphene powder in a solvent, and can also improve the affinity between the graphene powder and the organic polymer. That is, the graphene powder can be stably dispersed in a polar aprotic solvent, so that it can be intimately mixed with the organic polymer to prepare a conductive polymer. For example, as long as 1% of graphene is mixed in the plastic, it can be converted into electricity. The conductor, adding a very small amount of graphene, the plastic can be more heat-resistant to 30 degrees Celsius, and more durable.

Another feature of the present invention is that by chemically modifying the structure or properties of graphene, some "super substances" which are as thin, flexible and light as graphene can be made stronger and more widely used. Applicability, for example, Australia has developed a graphene paper that is 6 times lighter in weight, 5 to 6 times smaller in density, 2 times stronger in strength, and 10 times stronger in tensile strength than ordinary steel. The bending stiffness is 13 times larger. More and more metal materials have been replaced by carbon-based materials in the past 10 years. At present, many aircraft and automobile manufacturers have begun to replace metal materials with carbon fiber materials, and the performance of graphene paper and carbon fiber materials. Compared to graphene paper, it is undoubtedly better. In the future, this kind of synthetic "super substance" can be used to manufacture artificial satellites, airplanes and automobiles.

The above is only a preferred embodiment for explaining the present invention, and is not intended to limit the present invention in any way, and any modifications or alterations to the present invention made in the spirit of the same invention. All should still be included in the scope of the intention of the present invention.

The first figure is a schematic illustration of surface modified graphene in accordance with an embodiment of the present invention.

The second figure is a schematic representation of the epoxy structure used in Example 4.

Claims (10)

A surface-modified graphene comprising: a graphene powder; and at least one surface modifying layer, the at least one surface modifying layer comprising a surface modifying agent comprising at least a difunctional group, respectively located on the surface modification At the two ends of the agent, the at least difunctional monofunctional group is chemically bonded to the organofunctional group on the surface of the graphene powder, and the other functional group of the at least difunctional group forms the surface of the surface modified graphene The property wherein the surface modifying agent comprises at least one of a coupling agent, a fatty acid, and a resin. The surface-modified graphene according to claim 1, wherein the coupling agent has a structure of M _x (R) _y (R') _z , wherein M is a metal element, and R is a hydrophilic functional group. , R' is a lipophilic functional group, wherein 0≦x≦6,1≦y≦20, and 1≦z≦20. The surface-modified graphene according to claim 2, wherein the M system is one selected from the group consisting of aluminum, titanium, zirconium and hafnium. The surface-modified graphene according to claim 2, wherein R is selected from the group consisting of an alkoxy group, a carbonyl group, a carboxyl group, a decyloxy group, a decylamino group, an alkoxy group, and an alkylene oxide group. . The surface-modified graphene according to claim 2, wherein R' is selected from the group consisting of vinyl, aliphatic epoxyalkyl, styryl, methacryloxy, propyleneoxy, aliphatic Amine, chloropropyl, aliphatic thiol, aliphatic thiol, isocyanate, aliphatic urea, aliphatic carboxy, aliphatic hydroxy, cyclohexane, phenyl, aliphatic methyl fluorenyl One of acetaminophen and benzamidine. The surface-modified graphene according to claim 1, wherein the fatty acid is one selected from the group consisting of stearic acid and oleic acid. The surface-modified graphene according to claim 1, wherein the resin is one selected from the group consisting of epoxy resins, polyurethane resins, enamel resins, phenol resins, and polyester resins. The surface-modified graphene according to claim 1, wherein the surface modifier is between 0.1 and 10.0% by weight of the surface-modified graphene. The surface-modified graphene according to claim 1, wherein the at least one surface modifying layer comprises a first surface modifying layer and a second surface modifying layer, wherein the first surface is modified The layer is a coupling agent layer, and the second surface modifying layer is a resin layer. The surface-modified graphene according to claim 1, wherein the at least one surface modifying layer comprises a first surface modifying layer, a second surface modifying layer and a third surface modifying layer. The first surface modifying layer is a coupling agent layer, the second surface modifying layer is a resin layer, and the third surface modifying layer is a coupling agent layer.