CN110498920B

CN110498920B - Nano composite of conductive polymer and graphene and preparation method thereof

Info

Publication number: CN110498920B
Application number: CN201810481446.9A
Authority: CN
Inventors: 黄美荣; 李新贵; 于佳雪; 范武略
Original assignee: Tongji University
Current assignee: Tongji University
Priority date: 2018-05-18
Filing date: 2018-05-18
Publication date: 2020-11-27
Anticipated expiration: 2038-05-18
Also published as: CN110498920A

Abstract

The invention relates to a nano composite of a conductive polymer and graphene and a preparation method thereof. The invention utilizes the characteristic that the surface tension of the conductive polymer monomer is just matched with the surface tension required by graphite stripping, the liquid conductive polymer monomer is used as a stripping agent, and the stripping solvent and the subsequent polymerized monomer are unified to form the same component. Compared with the prior art, the stripping polymerization system does not introduce any other second solvent or stabilizer or surfactant, only plays the dual functions of stripping and polymerization by depending on the same component, and fundamentally ensures the purity of the obtained nano composite, thereby solving the problem that graphene prepared by other liquid phase stripping methods inevitably has residues of stripping solvent and auxiliary additive. The polymerized monomer is used as an exfoliant, and the idea of preparing the graphene nano-composite by the method is not reported.

Description

Nano composite of conductive polymer and graphene and preparation method thereof

Technical Field

The invention relates to the technical field of graphene composite preparation, in particular to a nano composite of a conductive polymer and graphene and a preparation method thereof.

Background

The graphene is composed of a single layer of SP²The honeycomb hexagonal planar crystal formed by arranging the hybridized carbon atoms has excellent electrical property, thermal property and mechanical property. Single-layer graphene at the atomic level was first prepared by Geimy research group in 2004 through micromechanical lift-off (Novoseov K S, Geim A K, Morozov S V, Jiang D, Zhang Y, Dubonos S V, Grigiova I V, first A.A.electric field effect in atomic thickness in carbon ms film science,2004,306(5696):666-669), thereby opening up a new era of graphene research. In two major preparation methods of graphene, from Bottom to Top (Bottom-Up) and from Top to Bottom (Top-Down), the former mainly involves a micromachining technical approach, is easy to prepare, can also prepare single-layer and few-layer graphene with higher quality, but has harsh conditions (high temperature and high vacuum) and is difficult to produce in quantity. The latter uses graphite as raw material, and prepares graphene through intercalation, liquid phase stripping, oxidation reduction and other ways, and has mass production potential. The liquid phase stripping method has the advantages of low preparation cost, simple and easy operation, few defects of the obtained graphene and the like, and is highly concerned. Effective liquid phase stripping systems include various organic solventsAgents (Hernandez Y, Nicolossiv, Lotya M, et al, high-yield Production of Graphene by liquid-Phase evolution of Graphene. Nature Nanotechnology 2008,3: 563-568; Coleman J N.liquid evolution of defect-Free Graphene. Account Chemical Research 2013,46(1): 14-22) and aqueous systems with various surfactants (Lotya M, Hernantz Y, King P J.et al, liquid Phase Production of Graphene by of Graphene evolution of Graphite in surface chemicals 2009,131:3611 3620; patent 201110456632.5). The concentration of some Graphene dispersion liquid can also reach very High concentration and realize rapid dispersion through various processes (Khan U, Porwal H, O' Neill A, et al, solvent-dispersed Graphene at exchange High concentration. Langmuir 2011,27: 9077-. However, the graphene obtained in this way has solvent residues due to high boiling point and low vapor pressure of the organic solvent used, or cannot be removed due to strong interaction between the added surfactant and the large pi bond of graphene. Although the amount of these impurities is small, the influence of the impurities on the performance of graphene is fatal, and if the graphene composite is further prepared by using the impurities as a raw material, the original performance of graphene cannot be sufficiently achieved.

As a branch of conductive polymers, the construction of nanocomposites or nanohybrids thereof with Graphene and the application thereof to high-efficiency electrochemical Capacitors have become one of the hot spots of research in the field of nanocomposites (Bae J, Park J Y, Kwon O S, Lee C S. energy Efficient Capacitors based on Graphene/reducing Polymer hybrids.j.ind.eng.chem.2017,51: 1-11.). For nanocomposites used as electrode sensors, the conducting polymer and graphene nanocomposite on the electrode sensor can be electrochemically polymerized in situ layer by layer (Raj M, Gupta P, Goyal R N, Shim Y.B. graphene/describing polymer nano-composite loaded scanned positive carbon sensor for simultaneous amplification of ions and 5-hydroxyl amplification. Sensors activators B.2017,239:993-1002). The composites do not require mass production, and are difficult to mass produce due to limitations of electrode area. Thus, electrochemically prepared conductive polymer/graphene composites are not within the scope of this discussion.

The graphene/conductive polymer nanocomposites with large-scale mass production potential can be prepared by three methods according to the polymerization priority of the conductive polymers:

(1) the direct blending method is to blend the two materials after they are prepared separately (Wu, Q.; Xu, Y.X.; Yao, Z.Y.; Liu, A.R.; Shi, G.Q.Supercapicitors Based on Flexible Graphene/polyurethane Nanofiber Composite films. ACS Nano 2010,4(4), 1963-. Obviously, the direct blending method is difficult to uniformly disperse the two, and the nano-scale compounding is more difficult to achieve, so that the method is not used much.

(2) The method is simple and easy to implement, and is a common composite mode. And adding an aniline monomer into the glycol dispersion liquid of GO, adding an oxidant ammonium persulfate and a glycol solution of hydrochloric acid, and then carrying out in-situ polymerization on the aniline monomer on a GO wafer to obtain a GO/PANI compound. And treating the GO with 8M NaOH solution at 90 ℃ to reduce the GO to obtain a Polyaniline/Graphene composite (Wang, H.; Hao, Q.; Yang, X.; Lu, L.; Wang, X.A Nanostructured Graphene/Polyaniline Hybrid Material for supercapacitors. Nanoscale 2010,2(10),2164-2170.Zhang, K.; Zhang, L.L.; Zhao, X.S.; Wu, J.Graph/Polyaniline Nanofiber Composites as supercapacitors electrodes. chem. Material. 2010,22 (4); 1392. 1401). However, due to the hydrophobic characteristic of the reduced graphene oxide, the graphene oxide is very difficult to keep in a stretched state in a hydrophilic solution, so that the reduced rGO is very easy to agglomerate and stack in a liquid phase, the improvement can be realized by adding a surfactant, and the system components become complicated and impure. In the process, the post-reduction of the graphene causes inevitable damage to the structure of the composite, meanwhile, the laminated structure layer upon layer also generates certain obstruction to the reduction of the graphene oxide, and the conductivity of the graphene which can not be completely reduced is greatly reduced due to the residue of oxygen-containing groups.

(3) Synchronous in-situ polymerization reduction method, namely, the in-situ polymerization of the conducting polymer is carried out while the nano rGO is reduced. The nano graphene can be in a two-dimensional planar shape or a three-dimensional stereo configuration, and the latter can be easily compounded in a nano scale. But the preparation process is complex and has certain uncertainty. Meanwhile, the rGO formed in situ also needs to be Stabilized by adding a surfactant to ensure that the reduced Graphene can be well dispersed in an aqueous solution (Mao, L.; Zhang, K.; On Chan, H.S.; Wu, J.Surfactant-Stabilized Graphene/polyannine nanofiller compositions for High Performance supercapacititor electrode.J.Mater.Chem.2012,22(1), 80-85.). This undoubtedly complicates the reaction components, with the risk of difficult complete removal.

Therefore, the hidden trouble of impure composition exists in the method for preparing the graphene compound by taking rGO as a raw material. Only direct liquid phase exfoliation of graphite without any additives can overcome this drawback. In fact, the direct liquid phase stripping method is not only a preparation method which can realize industrialization, but also is suitable for preparing the graphene composite material. However, if the stripping solvent is not properly selected, the resulting composite also has the potential to be compositionally impure. This problem can only be overcome by selecting solvent systems that do not remain. It can be seen that although many methods for preparing liquid-phase exfoliated graphene exist, the method for preparing graphene composites has the disadvantages of containing impurities such as residual solvents and metal elements, and particularly has the disadvantages of difficult redispersion, and the like, and the reported preparation of graphene composites cannot simultaneously realize the characteristics of simple operation, easy mass production, sufficient exfoliation, nano-scale compositing, and the like. Therefore, the method for preparing the high-quality graphene composite which is simple and feasible, high in yield and large in scale and has no impurity residue is significant.

Disclosure of Invention

The present invention is directed to overcoming the above-mentioned drawbacks of the prior art and providing a nanocomposite of a conductive polymer and graphene and a method for preparing the same.

The purpose of the invention can be realized by the following technical scheme:

in the first aspect of the present invention: adding a conductive polymer monomer into graphite as an organic solvent, carrying out sealed soaking on the graphite, taking out the graphite, carrying out continuous ultrasonic treatment or replacing a fresh conductive polymer monomer for carrying out multiple rounds of ultrasonic treatment, carrying out centrifugal separation on a product, and drying to obtain the graphene.

The conductive polymer monomer is selected from one or more of aniline, methylaniline, ethylaniline, propylaniline, N-methylaniline, N-ethylaniline or N-propylaniline; or the like, or, alternatively,

the conductive polymer monomer is selected from one or more of pyrrole.

The graphite is natural crystalline flake graphite or expandable graphite, and preferably expandable graphite.

The ratio of the graphite to the conductive polymer monomer is not more than 10/1(mg/mL), and is preferably 0.5/1 (mg/mL).

The soaking time of the graphite is 1 h-8 weeks, and preferably 1 week;

the soaking temperature of the graphite is room temperature-60 ℃, and the room temperature is preferred.

The temperature during the ultrasonic treatment is controlled to be between room temperature and 60 ℃, and is preferably 40 ℃;

two modes of ultrasound are selected, namely rod ultrasound or water bath ultrasound;

the ultrasonic frequency range is 20kHz to 70kHz, preferably 53 kHz;

the ultrasonic time is 1-100 h, and the higher the content is, the longer the ultrasonic time is, depending on the content of graphite in the conductive polymer monomer;

when multiple rounds of ultrasound are carried out, the number of ultrasound is 1 to 5, and the higher the content is, the more the number of ultrasound rounds is.

The drying includes freeze drying and vacuum drying.

Second aspect of the invention: adding a conductive polymer monomer into graphite as an organic solvent, soaking the graphite in a sealed manner, taking out the graphite, continuously performing ultrasonic treatment or replacing a fresh conductive polymer monomer to perform multi-round ultrasonic treatment, centrifuging a system after the ultrasonic treatment, absorbing redundant solvent in supernatant to obtain a blending system of the graphene and the conductive polymer monomer, adding an oxidant hydrochloric acid aqueous solution into the blending system of the graphene and the conductive polymer monomer, stirring and reacting, centrifuging, sucking an upper layer liquid out by a suction pipe, discarding the upper layer liquid, adding HCl into a lower layer precipitate, shaking and washing to remove oligomers and reaction byproducts, finally centrifuging, and drying a suspension to obtain the nano composite of the conductive polymer and the graphene.

One preferred embodiment is: adding a conductive polymer monomer into graphite as an organic solvent, soaking the graphite in a sealed manner, taking out the graphite, continuously performing ultrasonic treatment or replacing a fresh conductive polymer monomer, performing multi-round ultrasonic treatment, centrifuging the system after ultrasonic treatment, absorbing the redundant solvent in the supernatant to obtain a blending system of graphene and the conductive polymer monomer,

dropwise adding an oxidant hydrochloric acid aqueous solution into a blending system of graphene and a conductive polymer monomer under the condition of ultrasound or no ultrasound, and then stirring and reacting for 6-24 hours to obtain a dark black suspension. And (3) finishing the reaction, centrifuging for 90 minutes at 4000-10000 rpm, sucking out the upper layer liquid by using a suction pipe, discarding the upper layer liquid, adding 1M HCl into the lower layer precipitate, shaking by hand and violently shaking for washing, repeatedly washing for 5-6 times in such a way, thoroughly washing off oligomers and reaction byproducts, finally centrifuging to obtain a black suspension, placing the black suspension in a culture dish, precooling for 8 hours at-60 ℃ in a cold trap of a freeze dryer, then drying for 40 hours under 10Pa vacuum to obtain a nanocomposite of the conductive polymer and the graphene, and weighing and calculating the yield of the conductive polymer and the weight ratio of the conductive polymer to the graphene in the composite.

the conductive polymer monomer is selected from one or more of pyrrole.

The soaking time of the graphite is 1 h-8 weeks, and preferably 1 week;

the ultrasonic frequency range is 20kHz to 70kHz, preferably 53 kHz;

The drying includes freeze drying and vacuum drying.

The oxidant is ammonium persulfate or ferric trichloride.

The composite weight ratio of the conductive polymer to the graphene nano-composite is 60/40-99.9/0.1, and the preferable ratio is 80/20-99/1.

The actual yield of the conductive polymer obtained in the present invention and the actual weight percentage calculation formula of graphene in the conductive polymer/graphene nanocomposite are derived in detail as follows:

because the polymerization system is 1M HCl and the acid is removed in the polymerization process, the whole polymerization system is acidic, and the generated conductive polymer is in a doped state. The highest concentration of the generated sulfate radicals is only about 1/10 of the concentration of hydrochloric acid, so that the external doping agent is mainly HCl, and the yield Y of the conductive polymer is calculated by doping the conductive polymer with hydrochloric acid_dCP：

Y_dCP＝W_RdCP/W_TdCP＝(W_Total–Gw)/W_TdCP。。。。。。。。。。。。(1)

R_CP/G＝(W_Total–Gw)/G_w。。。。。。。。。。。。(2)

Y_dCP: yield of doped conducting polymer

R_CP/G: weight composite ratio of doped conductive polymer to graphene

W_RdCP: doped stateActual weight of conductive polymer;

W_TdCP: theoretical weight of doped conducting polymer;

W_Total: total weight of the resulting composite

Gw: graphene input weight

In a third aspect of the invention: the nano composite of the conductive polymer and the graphene prepared by the method is provided.

The innovation points of the invention are as follows: the method utilizes the characteristic that the surface tension of the liquid conductive polymer monomer is just matched with the surface tension required by graphite stripping, uses the liquid conductive polymer monomer as a stripping agent, and promotes more effective intercalation between the graphites by virtue of trace oligomer generated by the monomer in the ultrasonic process so as to increase the graphite stripping efficiency. The organic solvent after stripping can be converted into the required amount of reaction starting monomer after excessive amount is removed, and the residual monomer remained in the system and the graphene pi plane have conjugated interaction at the moment, so that the molecular level compounding is achieved. Therefore, the polymer nano-composite can be generated by in-situ polymerization after the oxidant is added. The stripping polymerization system does not introduce any other second solvent or stabilizer or surfactant, only depends on the same component to play the dual functions of stripping and polymerization, and fundamentally ensures the purity of the obtained nano-composite, thereby solving the problem that graphene prepared by other liquid phase stripping methods inevitably has residues of stripping solvent and auxiliary additive. The polymerized monomer is used as an exfoliant, and the idea of preparing the graphene nano-composite by the method is not reported.

The invention has the beneficial effects that: the liquid phase stripping method is a method capable of realizing industrial production and is also suitable for producing graphene composite materials. The method is different from other liquid phase stripping methods mainly in the selection of the stripping agent. The functional characteristic is that the stripping solvent and the subsequent polymerized monomer are unified, so that the stripping solvent and the subsequent polymerized monomer are the same component. The exfoliation process may be performed continuously, and if high-quality few-layer or single-layer graphene is desired, the exfoliated graphene may be taken out halfway and then subjected to multiple rounds of exfoliation. The stripping yield can reach 100 wt% only after a limited number of times of multi-round stripping, namely, all graphite is stripped into single-layer graphene and few-layer graphene. The conductive polymer may be a homopolymer or a copolymer. The nano-structure compound has fine composite structure and can achieve the nano-scale compounding in the real sense. The preparation method of the compound is simple to operate, and the obtained compound has pure composition and no residual solvent with high boiling point which influences the electrical conductivity. Meanwhile, the method is economical and effective, has simple process and can realize large-scale preparation.

Drawings

Fig. 1 is an ultraviolet-visible spectrum of the graphene dispersion liquid obtained in example 11 diluted by 6 times;

FIG. 2 is a TG curve of the nanocomposite of copolyalniline and graphene prepared in example 5;

fig. 3 is a scanning electron micrograph of the nanocomposite of the copolyalniline and graphene prepared in example 5 and example 8.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments.

Examples 1 to 2

The graphite is expanded by an instant high-temperature expansion method. Weighing 0.5g of graphite, putting the graphite into a ceramic crucible, putting the ceramic crucible into a muffle furnace heated to 950 ℃, immediately taking out the graphite after the graphite expands after several seconds, putting the graphite on a temperature-resistant experiment table, covering the experiment table, cooling the graphite to be close to room temperature, and putting the graphite in a dryer filled with blue silica gel for cooling. The expanded graphite is obtained, weighed and measured, the expansion rate (mL/g) is calculated according to a formula (3), the results of three parallel experiments of 2 graphene varieties are shown in table 1, and the conductivity of the expanded graphite measured by a four-probe method after tabletting is also shown in table 1.

Expansion ratio (mL/g) V₂/m₂ (3)

TABLE 1 change in volume and mass of graphite before and after high-temperature expansion and expansion ratio thereof

Example 3

Placing 6.5mg of commercial graphene powder in 100mL of 1M hydrochloric acid solution, carrying out intermittent ultrasonic treatment in a water bath for 2h (53kHz,180W, 100%), adding 0.9mL of aniline and 0.5g of o-aminophenol sulfonic acid, and continuing ultrasonic treatment for 15 min; and adding 3.0g of ammonium persulfate into 50mL of water to prepare an oxidant solution, performing ultrasonic treatment for 15min to accelerate dissolution, and dropwise adding the ammonium persulfate oxidant solution into the monomer solution. And (3) continuously stirring for reacting for 24 hours, then finishing the reaction, centrifuging for 30min at 3000rpm, sucking out the supernatant by using a straw, discarding, adding 1M HCl into the lower-layer precipitate, sealing the bottle mouth, shaking by hand, washing for 5-6 times, thoroughly washing off oligomers and reaction byproducts, centrifuging to obtain a black suspension, placing the black suspension into a culture dish, placing the black suspension into a cold trap of a freeze dryer, pre-cooling for 8 hours at-60 ℃, and then drying for 40 hours under 10Pa vacuum to obtain a nano composite of the copolyalniline and the graphene, wherein the polymerization yield of the copolyalniline is 51.8% by weight calculation, and the conductivity is 0.0142S/cm by using a four-probe by a tabletting method.

Example 4

The advantages of water bath ultrasound-assisted polymerization are demonstrated.

The graphene and monomer dosage and other experimental conditions in example 3 were kept unchanged, but the stirring mode of dropwise adding the oxidant solution was changed to a water bath ultrasonic mode (53kHz,180W, 100%), during which time the temperature control of the water bath was increased to keep it below 50 ℃. But when the oxidant is added dropwise, an ultrasonic process is added, so that the polyaniline/graphene nanocomposite can be prepared. And (3) obtaining the nano composite of the polyaniline and the graphene, wherein the polymerization yield of the polyaniline is 50.0% by weight calculation, and the conductivity is 0.223S/cm by four probes of a tabletting method. The conductivity of the resulting composite increased 15.8 times after the ultrasound-assisted polymerization process.

Example 5

A vial of known accurate weight was charged with 13mg of expanded graphite and 20mL of aniline, and the SK3300HP ultrasonic cleaner was subjected to water bath sonication at 180W and 53kHz for 48 h. After centrifugation at 3000rpm for 90min, all graphene including both monolayer and bilayer settled down, the supernatant was aspirated and discarded, but the weight of the remaining material in the vial was just 13+744.8 ═ 757.8mg, (the empty vial weight was removed), yielding 13mg dispersion of graphene in 0.73mL aniline. 378.4mg of aniline hydroxysulfonate was added to 100mL of 1M HCl, and the mixture was dissolved by shaking and then added to the graphene dispersion. In addition, 2.28g of ammonium persulfate is added into 50mL of hydrochloric acid to prepare an oxidant solution, and the ammonium persulfate oxidant solution is dropwise added into the monomer solution under the assistance of water bath ultrasound. Continuously stirring for reaction for 24h, finishing the reaction, centrifuging for 90min at 4000rpm, sucking out the supernatant by a straw, discarding, adding 1M HCl into the lower-layer precipitate, sealing the bottle mouth, shaking by hand shaking, washing by shaking violently, centrifuging for 90min at 3000rpm, repeatedly washing for 5-6 times in such a way, completely washing off oligomers and reaction byproducts, centrifuging to obtain a black suspension, placing the black suspension into a culture dish, placing the black suspension into a cold trap of a freeze dryer, pre-cooling for 8h at-60 ℃, then drying for 40h under 10Pa vacuum to obtain 645.6mg of a nanocomposite of the polyaniline and the graphene, calculating the polymerization yield of the polyaniline to be 50.2%, wherein the composite ratio of the copolymer and the graphene in the composite is 98/2, and the conductivity measured by a four-probe of a tabletting method is 9.73 multiplied by 10^-2S/cm. The specific test data of the electrical conductivity of each point of the pressed sheet are shown in Table 2.

Table 2 powder tableting point conductivities of copolyaniline and graphene composites prepared in example 5

Example 6

Example 5 was repeated, but after the graphite exfoliation was completed, the original organic solvent was completely removed and discarded, and the desired amount of fresh organic monomer was used to synthesize the copolymer, thereby obtaining 522.2mg of the nanocomposite of the polyaniline and the graphene, wherein the polymerization yield of the polyaniline was calculated to be 40.3%, the composite ratio of the copolymer to the graphene in the composite was 98/2, and the conductivity was measured to be 3.06 × 10 with a four-probe tablet press method^-3S/cm, and the conductivity of the obtained compound is lower than that of the original 1/3 under the same compound ratio. Specific test number of electrical conductivity of each point of the pressed sheetSee table 3. Therefore, the contribution of the conjugated interaction of the stripped graphene and the monomer to the conductivity of the copolymerized aniline can be seen.

TABLE 3 conductivity of each dot of a powder pellet (thickness of 0.376mm) of the copolyalniline and graphene composite prepared in example 6

Example 7

Example 5 was repeated, but the amount of graphene was changed to 3mg, to finally obtain 533.1mg of nanocomposite of copolyalniline and graphene, the calculated polymerization yield of the copolyalniline was 41.5%, the composite ratio of the copolymer to graphene in the composite was 99.5/0.5, and the conductivity measured by the four-probe tabletting method was 1.1 × 10^-3S/cm。

Example 8

6.5mg EG and 20mL aniline are added into a 30mL glass test tube with known accurate weight, the glass test tube is placed into an SK3300HP ultrasonic cleaning machine (180W,53kHz), water bath ultrasonic treatment is carried out for 20 hours at 100% power, after the first round of peeling is completed, the glass test tube is centrifuged at 900rpm for 45 minutes, 14mL of 70% upper layer liquid is sucked into the 100mL glass test tube, and the glass test tube is tightly covered with a bottle cap and is stored for standby. Adding 14mL of fresh aniline to the un-stripped graphite at the bottom of the original bottle, carrying out a second round of stripping for 20h, and collecting the supernatant of the 2 nd round into the 100mL glass test tube; this was followed by 5 rounds of peeling. After the 5 th round of stripping and centrifuging, no residual expanded graphite solid exists on the tube wall.

All collected 5 rounds of supernatant were centrifuged at 4000rpm for 90min at 76mL to settle all graphene including both monolayers and bilayers, and the supernatant was gradually aspirated and discarded to give a weight of just 6.5+744.8 mg 751.3mg remaining in the bottle, giving a dispersion of 6.5mg graphene in 0.73mL aniline. 378.4mg of aniline hydroxysulfonate was added to 100mL of 1M HCl, and the mixture was dissolved by shaking and then added to the graphene dispersion. In addition, 2.28g of ammonium persulfate is added into 50mL of hydrochloric acid to prepare an oxidant solution, and the ammonium persulfate oxidant solution is dropwise added into the monomer solution under the assistance of water bath ultrasound. And (3) continuously stirring for reacting for 24 hours, then finishing the reaction, centrifuging for 90 minutes at 4000rpm, sucking out the supernatant by using a suction pipe, discarding, adding 1M HCl into the lower-layer precipitate, sealing the bottle mouth, shaking by hand, washing for 90 minutes at 4000rpm, repeatedly washing for 5-6 times in such a way, thoroughly washing off oligomers and reaction byproducts, centrifuging to obtain a black suspension, placing the black suspension into a culture dish, placing the black suspension into a cold trap of a freeze dryer, pre-cooling for 8 hours at-60 ℃, and then drying for 40 hours under 10Pa vacuum to obtain 630.72mg of a nanocomposite of the polyaniline and the graphene, wherein the polymerization yield of the polyaniline is calculated to be 56.2%, the composite ratio of the copolymer and the graphene in the composite is 99/1, and the conductivity is 1.2S/cm measured by using a four-probe of a tabletting method.

Comparing the nanocomposites made in example 4 using commercial graphene, it was found that the conductivity of the nanocomposite obtained using the graphene prepared in example 8 according to the present invention was 5.4 times higher (1.2S/cm vs.0.223s/cm), representing the value of in-situ exfoliation polymerization.

Example 9

Example 8 was repeated, but the amount of graphene was changed to 35mg, and finally 539.8mg of the nanocomposite of the polyaniline and the graphene was obtained, the calculated polymerization yield of the polyaniline was 42.0%, the composite ratio of the copolymer to the graphene in the composite was 94/6, and the conductivity measured by the four-probe tabletting method was 10.9S/cm.

Example 10

Example 8 was repeated, but the amount of graphene was changed to 50mg, and finally 527.6mg of the nanocomposite of the polyaniline and the graphene was obtained, the calculated polymerization yield of the polyaniline was 41.0%, the composite ratio of the copolymer to the graphene in the composite was 91/9, and the conductivity measured by the four-probe tabletting method was 63.7S/cm.

Example 11

In-situ polymerization after 3 weeks immersion in aniline and stripping

20mg of graphite is poured into a 30mL glass test tube, 20mL of aniline is added, the test tube is sealed and soaked for 3 weeks at room temperature, the soaking is favorable for wetting the vermicular pore canal structure by a solvent, and even the graphite microcrystal is fully wetted by the capillary phenomenon of the vermicular pore canal, so that the stripping of the graphite is promoted. After the completion of the soaking, the graphite was peeled in a plurality of cycles in example 8, and it was found that the peeling of the graphite was completed in 6 cycles, and the peeling rate reached 100%. Each timeThe ultraviolet-visible spectrum of the wheel-peeled graphene dispersion liquid after 6-time dilution is shown in figure 1, and the absorbance A of the graphene diluted by 6 times to 660nm can be seen₆₆₀The highest concentration can reach 2.4659, and the concentration of the graphene can be estimated to be 0.337mg/mL according to the measured absorption coefficient of the graphene of 4388L/(g.m).

All 6 collected rounds of supernatant 110mL were centrifuged at 4000rpm for 90min, all graphene including mono-and bi-layers settled down, and the supernatant was gradually aspirated and discarded to give a weight of just 20+744.8 to 764.8mg remaining in the bottle, which gave a dispersion of 20mg graphene in 0.73mL aniline. In addition, 2.28g of ammonium persulfate is added into 50mL of hydrochloric acid to prepare an oxidant solution, and the ammonium persulfate oxidant solution is dropwise added into the monomer solution under the assistance of water bath ultrasound. And (3) continuously stirring for reacting for 24 hours, then finishing the reaction, centrifuging for 90 minutes at 4000rpm, sucking out the supernatant by using a suction pipe, discarding, adding 1MHCl into the lower-layer precipitate, sealing the bottle mouth, shaking by hand, washing for 90 minutes at 4000rpm, repeatedly washing for 5-6 times in such a way, thoroughly washing off oligomers and reaction byproducts, centrifuging to obtain a black suspension, placing the black suspension into a culture dish, placing the black suspension into a cold trap of a freeze dryer, pre-cooling for 8 hours at-60 ℃, and then drying for 40 hours under 10Pa vacuum to obtain 977.82mg of a nanocomposite of the polyaniline and the graphene, wherein the polymerization yield of the polyaniline is calculated to be 74.5%, the composite ratio of the copolymer and the graphene in the composite is 98/2, and the conductivity is 17.6S/cm measured by using a four-probe of a tabletting method.

Example 12

Exfoliation of graphite in pyrrole

Putting 6.5mg EG into a 100mL round-bottom flask, adding 13mL pyrrole to prepare the material with EG content of 0.5mg/mL, sealing and soaking for 52 days, then putting the material into an SK3300HP ultrasonic cleaning machine (180W,53kHz), carrying out water bath ultrasound for 20h at 100% power, after finishing the first round of peeling, centrifuging at 900rpm for 90min, sucking 70% of supernatant liquid into a 100mL glass test tube, and closing the bottle cap to store for later use. The un-exfoliated graphite in the bottom of the original bottle is supplemented with 10.0mL of fresh pyrrole for 2 nd round of 45h exfoliation, and the supernatant of the 2 nd round is collected into the above 100mL glass test tube. A total of 30mL of the graphene pyrrole dispersion was collected after 3 cycles of exfoliation. The graphene pyrrole dispersion liquid is recovered by ultrasonic treatment for 30min, 50 mu L of the graphene pyrrole dispersion liquid is diluted by fresh pyrrole by 6 times (1:5) and then subjected to ultraviolet and visible spectrum scanning (fresh pyrrole reference), the absorbance at 660nm is measured, and the concentration of the obtained graphene pyrrole dispersion liquid is calculated by taking 4419L/(g.m) as an absorption coefficient, and the result is shown in Table 4.

Table 4 multi-round exfoliation results of graphene in pyrrole

Example 13

Transferring 13.0mL of graphene dispersion liquid after stripping for 50h into a centrifuge tube, centrifuging at 10000rpm for 90min, settling all graphene, gradually sucking supernatant liquid and discarding the supernatant liquid to ensure that the weight of the residual substance in the bottle is just 6.5+ 332.8-339.3 mg, thus obtaining 6.5mg of graphene in 0.343mL of pyrrole (the density is 0.967 g/cm)³) The dispersion of (1). This dispersion was transferred to a conical flask containing 100mL of 1M HCl and was ready for use. 1.131g (0.554g) of ammonium persulfate was added to 25mL of 1M HCl to prepare an oxidant solution, and the ammonium persulfate oxidant solution was added dropwise to the monomer solution with the assistance of water bath ultrasound. Continuing to perform ultrasonic reaction for 6 hours at room temperature, then magnetically stirring for 18 hours at room temperature to finish the reaction, centrifuging for 90 minutes at 4000rpm, sucking out the supernatant by using a suction pipe, discarding, adding 1M HCl into the lower precipitate to seal the bottle mouth, shaking by hand, washing violently, centrifuging for 90 minutes at 4000rpm, repeatedly washing for 5-6 times in such a way, thoroughly washing off oligomers and reaction byproducts, freeze-drying to obtain 355.22mg of the polypyrrole-graphene nano-composite, calculating the polymerization yield of the polypyrrole to be 84.4%, specifying the composite ratio of the polymer and the graphene in the composite shown in Table 5 to be 98/2, and measuring the conductivity by using a four-probe tabletting method to be 0.018S/cm respectively. See table 6 for details

TABLE 5 polypyrrole/graphene nanocomposites prepared by in situ polymerization

Table 6 powder compaction point conductivities of polypyrrole and graphene composites prepared in example 13

Example 14

The same as example 13, except that the compounding ratio of the composite was different. After all graphene was allowed to settle, the weight of the material remaining in the bottle was exactly 6.5+163.0 to 169.5mg, yielding a dispersion of 6.5mg graphene in 0.168mL pyrrole. 177.0mg of polypyrrole-graphene nano-composite is obtained through polymerization, the polymerization yield of polypyrrole is calculated to be 78.3%, the composite ratio of the polymer and the graphene in the composite is 96/4, and the conductivity measured by a four-probe tabletting method is 0.13S/cm respectively. The results are shown in Table 5.

Example 15

Thermogravimetric analysis

13.4mg of the prepared copolyalniline and graphene composite of example 5 was placed in a crucible and heated at a heating rate of 10 ℃/min in an air atmosphere to obtain a thermogravimetric analysis curve TG and a differential curve DTG thereof as shown in FIG. 2. It can be seen that the weight of the nanocomposite is gradually reduced with the increase of the heating temperature, and when the temperature reaches about 100 ℃, a weight loss peak occurs, which is caused by the loss of natural equilibrium water in the main nanocomposite; the weight of the nanocomposite then decreased further with increasing temperature, with a relatively uniform rate of weight loss, until the composite was fully decomposed at 530 ℃.

Example 16: SEM (scanning Electron microscope)

A small amount of the polyaniline/graphene nanocomposite prepared in example 8 and having a composite ratio of 99/1 was added to absolute ethyl alcohol, ultrasonically dispersed, dropped on a silicon wafer, sprayed with gold after the ethanol was volatilized, and observed under a Scanning Electron Microscope (SEM) of Quanta 200 (FEI corporation, USA), and the SEM photograph is shown in FIG. 3. The submicron copolymerized aniline particles which exist freely can be seen, and the copolymerized aniline particles are attached to the graphene, and particularly, the copolymerized aniline is inserted between graphene nanosheets to form a composite structure coated with a graphene wafer. This form of composite structure is difficult to achieve in conventional composite processes.

The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.

Claims

1. A preparation method of a nano composite of a conductive polymer and graphene is characterized in that a conductive polymer monomer is added into graphite to serve as an organic solvent, the graphite is soaked in a sealed mode, continuous ultrasonic treatment or replacement of a fresh conductive polymer monomer is carried out after the graphite is taken out to carry out multiple rounds of ultrasonic treatment, a system is centrifuged after the ultrasonic treatment, excess solvent in supernatant is absorbed, a blending system of the graphene and the conductive polymer monomer is obtained, and conjugated interaction occurs between the residual conductive polymer monomer in the blending system of the graphene and the conductive polymer monomer and a graphene pi plane to achieve molecular level compounding;

adding an oxidant hydrochloric acid aqueous solution into a blending system of graphene and a conductive polymer monomer, stirring for reaction, centrifuging, sucking an upper layer liquid out by a suction pipe, discarding, adding HCl into a lower layer precipitate, shaking and washing, washing off oligomers and reaction byproducts, centrifuging, and drying a suspension to obtain the nanocomposite of the conductive polymer and the graphene.

2. The method according to claim 1, wherein the conductive polymer monomer is selected from one or more of aniline, methylaniline, ethylaniline or propylaniline; or the like, or, alternatively,

the conductive polymer monomer is selected from pyrrole.

3. The method according to claim 1, wherein the conductive polymer monomer is selected from one or more of N-methylaniline, N-ethylaniline, and N-propylaniline.

4. The method according to claim 1, wherein the graphite is natural flake graphite or expandable graphite.

5. The method of claim 4, wherein the graphite is expandable graphite.

6. The method according to claim 1, wherein the ratio of the graphite to the monomer of the conductive polymer is not more than 10/1 (mg/mL).

7. The method of claim 6, wherein the ratio of graphite to conductive polymer monomer is 0.5/1 (mg/mL).

8. The preparation method according to claim 1, wherein the graphite is soaked for 1h to 8 weeks; the soaking temperature of the graphite is between room temperature and 60 DEG C^oC。

9. The method of claim 8, wherein the graphite is soaked for 1 week; the soaking temperature of the graphite is room temperature.

10. The method according to claim 1, wherein the temperature during the ultrasonication is controlled to be in a range of room temperature to 60 ℃^oC；

the ultrasonic frequency range is 20kHz to 70 kHz;

the ultrasonic time is 1-100 h;

when multiple rounds of ultrasound are carried out, the ultrasound frequency is 1 to 5 times.

11. The method according to claim 10, wherein the temperature during the ultrasonication is controlled to 40 degrees C^oC; the ultrasonic frequency was 53 kHz.

12. The method according to claim 1, wherein the oxidizing agent is ammonium persulfate or ferric chloride.

13. The preparation method according to claim 1, wherein the composite weight ratio of the conductive polymer to the graphene in the nanocomposite of the conductive polymer and the graphene is 60/40-99.9/0.1.

14. The preparation method of claim 13, wherein the nanocomposite of the conductive polymer and the graphene has a composite weight ratio of the conductive polymer to the graphene of 80/20-99/1.

15. The nanocomposite of the conductive polymer and graphene prepared by the method of claim 1.