阅读说明：本技术 官能化石墨材料 (Functionalized graphite material ) 是由 约尔马·维尔塔宁 于 2013-04-30 设计创作，主要内容包括：本发明公开了用于使石墨材料官能化的方法的一种或多种技术,所述方法包括以下步骤：1)提供石墨材料；2)切割所述石墨材料；3)提供催化剂,其包括金属原子、金属阳离子、金属醇化物、金属链烷酸盐、金属磺酸盐和金属粉末中的至少一种催化剂；4)提供试剂；5)使所述催化剂结合至所述试剂；6)使所述试剂结合至所述石墨材料；以及7)回收所述催化剂。本发明还公开了一种由本文描述的所述方法制备的组合物。(The present invention discloses one or more techniques for a method of functionalizing graphitic materials, said method comprising the steps of: 1) providing a graphite material; 2) cutting the graphite material; 3) providing a catalyst comprising at least one catalyst of a metal atom, a metal cation, a metal alkoxide, a metal alkanoate, a metal sulfonate, and a metal powder; 4) providing a reagent; 5) binding the catalyst to the reagent; 6) binding the reagent to the graphitic material; and 7) recovering the catalyst. Also disclosed is a composition made by the method described herein.)

1. A method of functionalizing a graphitic material, said method comprising the steps of:

providing a graphite material;

cleaving the graphitic material, wherein said cleaving produces dangling bonds in the graphitic material, wherein said dangling bonds are radicals, carbenium ions, and/or carbanions;

providing a catalyst, the catalyst being a metal cation catalyst, wherein the catalyst comprises at least one of tosylate, aluminum isopropoxide, aluminum bromide, aluminum chloride, ferric chloride, palladium acetate, nickel acetate, zinc chloride, tin chloride, and cuprous chloride;

stabilizing the transient free radicals, carbenium and/or carbanion during catalysis, wherein the catalyst forms covalent, ionic and/or coordination bonds;

providing a reagent, wherein the reagent comprises at least one of an amino and epoxy reagent;

bonding the epoxy group to the catalyst, wherein the epoxy group undergoes ring opening; and is

Bonding the ring-opened epoxy groups to the graphite material.

2. The method of claim 1, wherein the graphitic material is carbon nanotubes or graphene.

3. The method of claim 1, wherein the cutting comprises at least one of: ultrasonic vibrators, sonotrodes, electromagnetic radiation, mechanical cutting, and shear forces.

4. The method of claim 2, wherein the graphitic material is carbon nanotubes, wherein the carbon nanotubes are bonded with an amine hardener, APTMS (3-aminopropyltrimethoxysilane), and nanoparticles.

5. The method of claim 4, wherein the nanoparticles are selected from the group consisting of silica nanoparticles, alumina nanoparticles, and titanium nanoparticles.

6. The method of claim 1, wherein the catalyst is at least one of aluminum isopropoxide, aluminum bromide, and aluminum chloride, wherein the method further comprises the steps of:

a free radical reaction initiator is provided.

7. The method of claim 6, wherein the free radical reaction initiator is dibenzoyl peroxide or dibenzoyl peroxide and bis-tert-butyl azide.

Background

Carbon Nanotubes (CNTs) and graphene have been used to reinforce thermosets such as epoxies, polyurethanes, and silicones. CNTs, functionalized CNTs (or hybrid CNTs, denoted as HNTs), carbon fibers, graphite, graphene, and functionalized graphene may be collectively referred to as graphite materials. The graphite material may have a high tensile strength. Composites and other hybrid materials can be made by incorporating graphitic materials into various matrix materials to improve tensile strength and other properties. For example, these graphite materials may be incorporated into any epoxy component such as epoxy resins and hardeners. Graphite materials may also be incorporated into polyurethanes and silicones. Such graphitic materials can interact with matrix materials and with each other by van der waals forces.

However, the mechanical and chemical properties of the composite may change. In order to provide composites and other hybrid materials with advantageous mechanical and chemical properties, several functionalization methods for graphitic materials can be used. These methods may include nitric/sulfuric acid oxidation of CNTs, aryl radical addition of CNTs, ball milling induced amine and sulfide addition to CNTs, butyl lithium activated coupling to alkyl halides, and ultrasonic vibration assisted addition of many reagents including amines and epoxy resins. These processes may or may not require any solvent or the formation of other by-products.

Disclosure of Invention

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key factors or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

In one embodiment, a method of functionalizing a graphitic material comprises the steps of: 1) providing a graphite material; 2) cutting the graphite material; 3) providing a catalyst comprising at least one catalyst of a metal atom, a metal cation, a metal alkoxide, a metal alkanoate, a metal sulfonate, and a metal powder; 4) providing a reagent; 5) binding the catalyst to the reagent; 6) binding the reagent to the graphitic material; and 7) recovering the catalyst.

To the accomplishment of the foregoing and related ends, the following description and annexed drawings set forth certain illustrative aspects and implementations. These are indicative of but a few of the various ways in which one or more aspects may be employed. Other aspects, advantages and novel features of the disclosure will become apparent from the following detailed description when considered in conjunction with the drawings.

Drawings

The invention may take physical form in certain parts and arrangement of parts, the description being in detail as illustrated in the accompanying drawings which form a part hereof, and wherein:

fig. 1 schematically illustrates what is disclosed herein.

Fig. 2 schematically illustrates what is disclosed herein.

Fig. 3 schematically illustrates what is disclosed herein.

Fig. 4 schematically illustrates what is disclosed herein.

Detailed Description

The claimed subject matter is now described with reference to the drawings, wherein like reference numerals are generally used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the claimed subject matter. It may be evident, however, that the claimed subject matter may be practiced without these specific details. In other instances, structures and devices are shown in block diagram form in order to facilitate describing the claimed subject matter.

The word "exemplary" is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, the various concepts are presented in a concrete fashion using the word exemplary. As used in this application, the term "or" means an inclusive "or" rather than an exclusive "or". That is, "X employs a or B" means any of the natural inclusive permutations unless specified otherwise or clear from the context. That is, if X employs A; b is used as X; or X employs both A and B, then "X employs A or B" is satisfied in any of the above examples. Further, at least one of a and B and/or similar descriptions typically means a or B or both a and B. In addition, the articles "a" and "an" as used in this application and the appended claims may generally be construed to mean "one or more" unless specified otherwise or clear from context to be directed to a singular form.

Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims. Of course, those skilled in the art will recognize many modifications may be made to this configuration without departing from the scope or spirit of the claimed subject matter.

Also, although the disclosure has been shown and described with respect to one or more implementations, equivalent alterations and modifications will occur to others skilled in the art based upon a reading and understanding of this specification and the annexed drawings. The present disclosure includes all such modifications and alterations and is limited only by the scope of the appended claims. In particular regard to the various functions performed by the above described components (e.g., elements, resources, etc.), the terms used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary implementations of the disclosure.

In addition, while a particular feature of the disclosure may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms "includes," has, "or variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term" comprising.

Described herein is a method of functionalizing graphitic materials comprising the steps of: 1) providing a graphite material; 2) cutting the graphite material; 3) providing a catalyst comprising at least one catalyst of a metal atom, a metal cation, a metal alkoxide, a metal alkanoate, a metal sulfonate, and a metal powder; 4) providing a reagent; 5) binding the catalyst to the reagent; 6) binding the reagent to the graphitic material; and 7) recovering the catalyst. Also described herein is a composition made by the method described herein.

Fig. 1 depicts a graphite material. The graphite material may include Carbon Nanotubes (CNTs) and graphene. Fig. 1 also provides for the functionalization of the graphitic material. The graphitic materials can be functionalized by the methods described herein and further used in hybrid materials. These methods are further applicable to all graphite materials.

In fig. 1, the aluminum catalyst may be introduced after cutting. The cutting method may include ultrasonic cutting and mechanical cutting by grinding using nano-or micro-particles as an actual cutting agent. The cleavage can be performed in the presence of an amine hardener comprising aminopropyltrimethoxysilane (also known as APTMS). The milling may be performed using nanoparticles so that the nanoparticles cannot be combined with the carbon nanotubes or graphene. Due to the high reactivity of the cut carbon nanotubes or graphene, bonding may occur even if the nanoparticles do not have any special surface functionalization. It is noted that the cutting may be performed in the absence of oxygen and water.

In addition, there may be optimal limitations for the functionalization induced by cleavage. The prolonged cleavage-induced reaction can result in smaller graphite particles. Smaller graphite particles may not provide the same mechanical properties as larger graphite particles.

The cutting method of the graphite material may include cutting a bond or cutting the whole CNT or other graphite particles. Cutting methods may include ultrasonic vibration, sonotrodes, mechanical cutting or shearing in the presence of microparticles or nanoparticles, shear forces, and electromagnetic radiation.

The ultrasonic vibrator may be made of a piezoelectric material. The piezoelectric material may be lead zirconium titanate. The piezoelectric material may be sandwiched between two electrodes. The frequency and amplitude of the ultrasonic vibrations can be adjusted by the potential and frequency of the AC field between the electrodes. The amplitude of the vibration may be limited by the thickness of the piezoelectric layer. The frequency may vary between about 10kHz and about 1MHz, although frequencies outside of these ranges may be used. The frequency may also vary between about 20kHz and about 30 kHz. The vibration amplitude may be between about 5 microns and about 200 microns. The vibration amplitude may also be between about 20 microns and about 120 microns.

The power of one sonotrode may be between about 0.1kW and about 50 kW. The power of one sonotrode may also be between about 1kW and about 20 kW. When multiple sonotrodes may be used, the power may be varied over time so that the interference pattern may be continuously varied. Thus, the entire reaction mixture can be agitated more uniformly.

Conventional sonotrodes can apply forces into a relatively small volume, especially if the medium may have a high viscosity. Sonotrodes that distribute ultrasonic vibrations into a larger volume can be used to accelerate the reaction rate.

Mechanical cutting may include a variety of methods well known in the grinding and milling arts. However, since crushing of CNTs and other graphitic materials can compromise the integrity of these materials, grinding and milling can be performed in the presence of sharp-edged microparticles and nanoparticles to obtain sharp cuts. Suitable particles may include salts such as sodium chloride, sodium cyanide, calcium oxalate, glass, quartz and ceramics such as alumina and zirconia.

Shear forces may also induce cleavage. The use of shear forces may require high pressure gradients. Industrial homogenizers may have a pressure of several hundred bar or even several thousand bar. The effect of shear forces can be amplified by the addition of micro-or nanoparticles. The salt may also be a reagent to which a crown ether or a phase transfer catalyst such as cetyltrimethylammonium bromide may be added. The shear force may be applied by microfluidically injecting the reagent mixture through a nozzle at high pressure. Two liquid streams directly opposite each other can be injected or injected against a solid wall. This method can be applied to all kinds of graphitic materials including graphite itself, as graphite will effectively delaminate and produce graphene, which will be simultaneously functionalized by the reagents present in the reaction mixture. CNTs can be dispersed and reacted using pressures between about 375,000mmHg (500bar) to about 2,250,000mmHg (3000 bar). For dispersing graphite, the pressure may be higher than about 1,500,000mmHg (2000 bar).

In another embodiment, ultrasonic vibration may be used to induce the reaction of the graphite material in the presence of the metal ion catalyst. The cutting of the graphite material may also induce mechanochemical reactions. The cleavage may provide free radicals within the graphitic material. The cutting may also provide carbanions within the graphite material. The metal can then bind to an electronegative carbanion.

The catalyst provided in fig. 1 may be bonded to where the graphite material may be cut. The addition of a coordinated metal atom or metal cation catalyst, such as a Friedel-Crafts, Sandmayer, Heck or Suzuki type catalyst, to the reaction mixture may have broad applicability. Several types of metal atoms or salts can be used as catalysts, including aluminum, iron, tin, zinc, magnesium, copper, palladium acetate, aluminum isopropoxide, aluminum bromide, aluminum chloride, ferric chloride, nickel acetate, zinc chloride, tin chloride, and cuprous chloride. Metal alcoholates may also be beneficial. In some cases, the fine metal powder may act like a catalyst in that the metal may react with one of the reagents to form a metal ion. For example, aluminum or magnesium powder may be reacted with an amine so that the resulting compound may be reactive. Other examples of catalysts may include ferrocene and titanocene.

The catalyst may still promote the reaction, for example by opening the epoxy ring. The catalyst may also promote the reaction at a point remote from the cleavage site. Reactive sites can be moved in a conjugated system by quantum mechanical resonance. At the same time, the reactivity of these sites may be reduced, but the catalyst may compensate for the reduction. The catalyst may form covalent, ionic, or coordinate bonds during catalysis, and may stabilize transient free radicals, carbenium ions, and carbanions.

Traditionally used Friedel-Crafts catalysts such as aluminum chloride may be poorly soluble in many solvents and may only weakly interact with graphitic materials, which are themselves poorly dispersible in most solvents. In these cases, metal alkanoates such as acetates, propionates, palmitates, or benzoates, trifluoromethanesulfonates or tosylates may be used. Examples may include aluminum toluenesulfonate and zinc trifluoromethanesulfonate. These catalysts can allow many monomers including acrylates, bis (isocyanates), silanes, epoxies, such as bisphenol diglycidyl ether and SU-8, to bond with graphitic materials including carbon nanotubes and graphene.

Figure 2 can provide stabilization of the catalyst and reagents. The reagent may include at least one of an amino and epoxy reagent. After reacting the catalyst with the reagent, the resulting complex may be stabilized in several different forms as shown in fig. 2.

Figure 3 can provide that a reagent such as an epoxy resin can react with soluble aluminum toluene sulfonate (figure 3A). The epoxy may bond and may undergo ring opening. As shown in fig. 3B, the opened epoxy may now bond to the graphite material.

Reagent groups that may be coupled to the graphitic material may include, but are not limited to, alkyl and aryl halides, tosylates and triflates, acyl halides, epoxides, and thiols. Alternatively, the diazonium salt may be reacted in the presence of a cuprous salt. The cutting may form dangling bonds in the graphite material. These dangling bonds, which may include radicals, carbenium ions, and carbanions, may be reactive.

In addition, any binding may include binding between different molecules. For example, carbon nanotubes can bind to at least three different molecules during the cutting process: 1) an amine hardener; 2) APTMS; and 3) nanoparticles such as silica nanoparticles and alumina nanoparticles. The carbon nanotubes may also be mixed with an epoxy resin that can be used to functionalize the carbon nanotubes such that the hardener or epoxy contains functionalized carbon nanotubes. Additionally, the epoxy resin and the hardener may both comprise functionalized nanotubes and nanoparticles. In addition, titanium nanoparticles may also be incorporated. Chemical bonding may be independent of particle size. Thus, large and micro particles can be combined in a similar manner.

In the methods described herein, an amine may also be added to the graphite material during cutting of the graphite material using aluminum isopropoxide as a catalyst. The reaction can take place in the absence of any catalyst, but in the presence of a catalyst an order of magnitude or more is often obtained. The alcoholate is basic and can catalyze the self-polymerization of some monomers, including epoxies. An alkoxide such as aluminum isopropoxide may be added to the reaction mixture initially, and a carboxylic or sulfonic acid may be added at a later stage to neutralize the alkoxide, thereby inhibiting the base-catalyzed reaction. Other catalysts may also be used, including free radical reaction initiators such as dibenzoyl peroxide and bis-tert-butyl azide, where aluminum catalysts may be used.

The mechanism of these catalysts in the processes described herein may not be determinable. However, without wishing to be bound by theory to the methods herein, the known mechanisms of Friedel-Crafts or Sandmayer reactions can be extrapolated to the present case. The catalyst may interact with the reagent, the graphitic material, or both. Metal cation-containing catalysts can at least transiently stabilize free radicals, anions, and cations of carbon, nitrogen, and sulfur, thereby creating reaction pathways that can have activation energies lower than corresponding reactions without the use of catalysts. In addition, the metal cations may prevent excessive delocalization of unpaired electrons or charges in the graphitic material. This may result in a higher reaction rate. Thus, the catalyst may stabilize the formation of reactive species from the reagent by slight delocalization of charge or free electrons, and may prevent excessive delocalization of charge or free electrons in the graphitic material. Either or both of these may occur independently, and may result in accelerated reaction rates and improved degrees of substitution. After the reagents can be bound to the graphitic material, the catalyst used in the methods described herein can be recovered.

The Suzuki reaction in the methods described herein may require the addition of at least a catalytic amount of a halogen or halide salt and trimethyl borate or some other borate ester. During sonication, halides may be formed and the Suzuki reaction may release the halides back into solution.

Many of the catalysts herein can form coordinate bonds with graphite materials. The bonding may assist in the solubilization of the graphitic material. Solubilization may facilitate the reaction.

The reaction can be further aided by the addition of other molecules that solubilize the CNTs. Cellulose and cellulose derivatives, such as acetyl cellulose and carboxymethyl cellulose, may be used.

Fig. 4 may provide a simplified depiction of the bonding of reagents to graphite materials through the use of a catalyst.

In the description herein, there is also described a functionalized graphite material prepared by a process comprising the steps of: 1) providing a graphite material; 2) cutting the graphite material; 3) providing a catalyst comprising at least one metal atom, metal cation, metal alkoxide, metal alkanoate, metal sulfonate, and metal powder; 4) providing a reagent; 5) binding the catalyst to the reagent; 6) binding the reagent to the graphitic material; and 7) recovering the catalyst.

In chemically coupling the graphitic material with a polymer as described herein, the graphitic material and other components such as monomers or polymers may often be temporarily functionalized with halogens, sulfonates, or other functional groups such as dimethylboron prior to actual coupling. The overall yield may be low, but may be sufficient.

The compositions and methods described herein with respect to the functionalized CNTs, materials, and methods can be used to reinforce materials such as thermoplastics, thermosetting resins, rubbers, metals, and concrete.