shielding material made up of polyaniline and graphene oxide and application thereof. The composite material of polyaniline filled with graphene oxide can find applications
. .
in the shielding of electromagnetic waves in the X-band region (8.2-12.4 GHz).

BACKGROUND OF INVENTION

This invention relates to a process for the making of EMI shielding materials with excellent shielding effectiveness. In this invention composites of polyaniline and graphene oxide were prepared by in-situ interfacial polymerization method which can find applications in the shielding of electronic gadgets from the incoming and outgoing electromagnetic waves. The process involves preparation of electrically conducting composites of polyaniline incorporated with graphene oxide by the in-situ interfacial polymerization of aniline in the presence of graphene oxide aqueous dispersion. After polymerization polyaniline/graphene oxide suspension was filtered and dried in vacuum oven. The as synthesized composites of polyanilinejgraphene oxide were
evaluated for EMI shielding applications.

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With the advancement of electronic world and excessive use of electromagnetic waves for industrial, household and communication applications shielding of electronic equipments becomes an essential practice. Since electromagnetic wave cause malfunctioning of these electronic gadgets as well as these waves when exposed to human beings can cause health hazards. Typical material of choice by shielding industry includes metals, metal nanoparticles but due to heavy weight, easy corrosion and cumbersome processing methods makes researchers to search for alternative materials. Conducting polymer nanocarbon based composites offers attractive tailorable properties and potential replacements to conventional metal based shielding materials. Conducting polymer composites of polyaniline encapsulating graphene oxide prepared

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Following are the works done so far in the field of conductive polymers based materials for EMI shielding:

(CN104163919A) Polyanilinefoxidized graphenejferriferrous oxide absorbing material and preparation method

The invention belongs to the field of electromagnetic wave absorbing material preparation and relates to a polyanilinefoxidized graphenejferriferrous oxide composite material and its preparation method. The preparation me!hod comprises the following steps: (1) preparing graphite oxide; (2) preparing ferriferrous oxide nanoparticles; (3) preparing a polyanilinefoxidized graphenejferriferrous oxide ternary complex; and (4) weighing the polyanilinefoxidized graphene/ferriferrous oxide ternary complex and paraffin, and uniformly mixing to obtain the polyanilinefoxidized graphene/ferriferrous oxide absorbing material. The material provided by the invention has characteristics of low cost, simple preparation technology, strong electromagnetic wave absorbing capability, wide absorption band, low density and the like, has good electromagnetic property, and has important
application value in the field of microwave absorption and electromagnetic shielding.

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(CN105330857A) Preparation method of PANI (polyaniline)-GO (graphene oxide)-CNTs (carbon nanotubes) composited electromagnetic shielding material The invention discloses a preparation method of a PANI (polyaniline)-GO (graphene oxide)-CNTs (carbon nanotubes) composited electromagnetic shielding material. The method comprises steps as follows: the CNTs and SDS (sodium dodecyl sulfate) are added to an HC104 solution, a solution a is obtained, GO is dispersed in the HC104 solution, a solution b is obtained, and a solution cis obtained after mixing ofthe solution a and the solution b; the solution c and aniline are mixed and put in a three-necked flask, a solution I is obtained after mixing in ice bath, APS (ammonium persulfate) is added to the HCI04 solution, and a solution II is obtained; the solution I and the solution II are mixed and react in ice bath, a black green solution is obtained and subjected to
suction filtration, and a PANI-GO-CNTs powder material is obtained; water, ethanol and

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acetone are adopted for respective washing until a filtrate is clear, finally, black green solid powder is put in a vacuum oven for drying, and after consistent weight is realized, the PANI-GO-CNTs composited electromagnetic shielding material is obtained. The

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material has large specific surface area and is higher in conductivity and convenient to prepare, and the technology is simple:

(CN102492296A) Sy11thesis method of water dispersible polyanilinejgraphene composite material

Belonging to the field of composite material preparation, the invention provides a preparation method of a polyanilinefgraphene composite material able to disperse in water stably. The material is prepared by the following steps of: 1) reducing graphene oxide to graphene with hydrazine hydrate; 2) dispersing the newly prepared graphene in a solution containing a macromolecular dispersant; 3) then adding aniline for dispersing; 4) at a low temperature, adding a solution of an oxidizing agent and an inorganic acid into the obtained mixed solution drop wisely, and conducting stirring for polymerization; and 5) carrying out centrifugation and washing, thus obtaining the polyanilinefgraphene composite material. Due to the auxiliary effect of the macromolecular dispersant, the polyanilinefgraphene composite material obtained in the invention can disperse uniformly in water and can be stored stably. And the obtained dispersed solution generates no sediment after 6 months of placement. Thus, the method of the invention solves the problem of difficult processing of a polyanilinefgraphene composite material.

(CN101492569A) Oxidized graphite flake layerfpolyaniline co posite material and method for preparing the same

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The invention relates to oxidized graphite sheet layer/polyaniline composite material and a preparation method thereof. The composite material is prepared by the following steps: the oxidized graphite is added into a dispersant for ultrasonic dispersion so as to form homodispersed single-sheet layer• oxidized graphite mixed liquor; at the room temperature, aniline is added into the mixed liquor obtained in the first step drop by drop, and the ultrasonic dispersion is carried out to form the mixed liquor; a solution obtained by adding an oxidant into doping acid is drop wise added into the mixed liquor

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obtained in the second step for stirring and polymerization; the mixed liquor obtained

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in the third step is centrifugated, washed and dried in vacuum so as to obtain the oxidized graphite sheet layerfpolyaniline composite material. The invention takes full advantages of big specific area of the oxidized graphite and surface oxygroup group to

form binding sites and is organically combined with polyaniline skeleton by the chemical doping function of carboxylic acid group on the single-sheet layer of the oxidized graphite so as to form oxidized graphitejpolyaniline complex; the operation process of preparing the product is simple, the production period thereof is short, the yield is high and the requirements on devices are low.

(US20100055025A1) Process for producing dispersible Nano Graphene Platelets from oxidized graphite

The present invention provides a process for producing nano graphene platelets (NGPs) that are dispersible and conducting. The process comprises: (a) preparing a graphite intercalation compound (GIC) or graphite oxide (GO) from a laminar graphite m(\terial; (b) exposing the GIC or GO to a first temperature for a first period of time to obtain exfoliated graphite; and (c) exposing the exfoliated graphite to a second temperature in a protective atmosphere for a second period of time to obtain the desired dispersible nano graphene platelet with an oxygen content no greater than 25% by weight, preferably below 20% by weight, further preferably between 5% and 20% by weight. Conductive NGPs can find applications in transparent electrodes for solar cells or flat panel displays, additives for battery and supercapacitor electrodes, conductive nanocomposite for electromagnetic wave interference (EMI) shielding and static charge
dissipation, etc.

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(CN102604533A) Polyaniline-graphene composite based anticorrosive paint and preparation method thereof
The invention provides polyaniline-graphene composite based anticorrosive paint and a preparation method thereof. The polyaniline-graphene composite based anticorrosive paint comprises, by weight, 20-90 parts of film former, 0.1-20 parts of polyaniline-
1
graphene composite, 1-10 parts of pigment, 1-10 parts of filler, 0.1-3 parts of sag-proof agent, 0.1-4 parts of dispersant, 0.01-2 parts of flatting agent, 0.01-2 parts of defoaming agent, and 1-50 parts of solvent. The paint has good physical anticorrosion as graphene

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is high iri radius-thickness ratio and high in flexibility and has electromechanical

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anticorrosion by the aid of polyaniline loaded on the surface of the graphene, and under

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synergism of the polyaniline and the graphene, the paint has fine metal corrosion resistance. The anticorrosive paint achieves passivation and corrosion inhibition of

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metal substrates, avoids use of heavy metals causing environmental pollution, such as chromium and the like, and is simple to prepare, low in cost and easy in industrial batch production.

(W02015001534A1) Method for the preparation of polyanilinejreduced graphene oxide composites

The present invention relates to a method for obtaining composites of polyaniline and reduced graphene oxide comprising the steps of dispersing the graphene oxide in an acid aqueous solution containing an anionic emulsifying agent to obtain a dispersion of the graphene oxide; dissolving an aniline oligomer in an organic solvent to obtain a solution of the oligomer; mixing the solution of the oligomer with the dispersion of graphene oxide to obtain a composite of polyaniline and reduced graphene oxide. A use of the composite is also described.

Objective of the Invention

The main objective of the present invention is to design conducting polymer composites by in-situ interfacial polymerization process to fabricate efficient, lightweight, conducting polymer composites structures of polyaniline graphene oxide for EMI shielding applications. The aim of the invention is to design highly efficient easy process
able, and corrosion resistant EMI shielding structures.

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Summary of the invention

Accordingly, the present invention provides a process of fabrication of conducting polymer composites of polyaniline encapsulating graphene oxide and EMI shielding applications thereof. The method co prising:

(a) Initially, aniline 0.1 M was dissolved in chloroform solvent to form the organic

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phase yvhile 0.1 M of ammonium persulphate was dissolved in 1M HCl aqueous solution
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to form aqueous phase.

(b) Now the aqueous phase was carefully added along the side of the beaker to the organic phase to produce a clear interface of aqueous and organic phase.

(c) The beaker was allowed to put in an ice bath to slow down the reaction rate. The polymerization of aniline occurred at the interface.
(d) After 12 hours of reaction, the upper aqueous phase was carefully separated from the organic phase and filtered.
(e) The filtrate was washed with water and then dried in vacuum oven at 60 °C.

(f) The EMI shielding effectiveness and dielectric attributes of conducting sheets of PYA was calculated from the scattering parameters measured by Agilent's vector network analyzer N5230C PNA & L.

In one embodiment of the inven ion, the conducting polymer chosen for the study was polyaniline.

In another embodiment of the invention, the filler used for the study was graphene oxide prepared by improved hummer method.

In another embodiment of the invention, the aqueous medium was used to dissolve 1 M HCl and 0.1M oxidant.

In another embodiment of the invention, the organic phase chloroform was used to dissolve 0.1 M aniline monomer.

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In another embodiment of the invention, the oxidant used for the polymerization of the aniline monomer was APS and alike.

In another embodiment of the invention, the aqueous solution was added carefully to the organic phase along the side of the beaker.

In another embodiment of the invention, the beaker was put into an ice bath polymerization reaction was occurred at the interface of the aqueous-organic phase.

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In another embodiment of the invention, the conducting composites of polyaniline

encapsulating graphene oxide were tested for EMI shielding applications.

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In the drawings accompanying this specification

Fig 1XRD patterns of polyaniline, GO, PNFS and PNF10 composites

Fig 2 FTIR spectrum of polyaniline, GO, PNFS and PNF10 composites

Fig 3 Variation of total shielding effectiveness of composites with frequency. Fig 4 Shielding effectiveness due to absorption loss.
Fig 5 Shielding effectiveness due to reflection loss.

Fig 6 Dielectric attributes behaviour of GO as a function of frequency.

Fig 7 Dielectric attributes behaviour of polyanilne as a function of frequency. Fig 8 Dielectric attributes behaviour of as a function of frequency.
Table 1 Different concentration of filler materials in polyaniline with total sh elding

effectiveness values at 8.2 GHz frequency

Method of preparation of graphene oxide

Graphene oxide was synthesized by the improved Hummer's method; process includes natural graphite (5 g) dispersed in a 9:1 mixture of concentrated HzS04/H3P04 (360:40 ml) at room temperature and the mixture was put in an ice bath. Then, KMn04 (40 g) was added very slowly so that the temperature of the mixture is not allowed to reach beyond 35 °C. The temperature was then raised up to 50 QC, and the suspension was stirred for 12 h. Distilled water (100 ml) was added very gradually, maintaining the temperature below 65 QC. The mixture was stirred for 1 hour by the addition of a large amount of deionized water (500 ml). Subsequently, addition of 30% HzOz solution (30 ml) to the above mixture caused violent effervescence and temperature was increased to 50°C, after which the color of the suspension changes from dark brown to bright yellow. The graphene oxide (GO) suspension was centrifuged (10000rpm, 30min)and the supernatant was decanted away. The remaining solid material was then washed two times in succession with 200 mL of water, 200 mL of 30% HCl, and 200 mL of ethanol in order to remove metal ions. For each wash, the mixture was centrifuged (10000 rpm for 30 min) and the supernatant decanted away. The paste collected was
dried at 80+5 oc in a vacuum oven.

Example 2

Method of preparation of polyaniline polymer

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Polyaniline was prepared by interfacial polymerization method; wherein 0.1 M of aniline was dissolved in chloroform organic solvent while 0.1 M of ammonium persulfate was dissolved in 1 M aqueous HCl solution. Now aqueous solution was carefully added along the sides of the beaker to the organic solution to form a clear interface and beaker was put into an ice bath. The polymerization reaction occurred at the interface of the aqueous-organic layers; after 12 hours of reaction the aqueous phase containing polyaniline was carefully separated from the organic phase. The
aqueous phase was filtered, washed with distilled water and dried in a vacuum oven.

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Example 3

Method of preparation of polyaniline encapsulating 5°/o graphene oxide (PNFS)

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Polyaniline encapsulating 5% graphene oxide was prepared by in-situ interfacial polymerization method. Initially, 5 wt% of graphene oxide dispersed in distilled water was sonicated for 2 hours for exfoliation of graphene oxide layers after that ammonium persulfate (0.1 M) and HCl (1 M) was dissolved in aqueous graphene oxide dispersion while 0.1 M of aniline was dissolved in chloroform organic solvent. Now aqueous dispersion of graphene oxide was carefully added along the sides of the beaker to the organic solution to form a clear interface and then beaker was put into an ice bath. The polymerization reaction occurred at the interface of the aqueous-organic layers; after
12 hours of reaction the aqueous phase containing polyaniline was carefully separated from the organic phase. The aqueous phase was filtered, washed with distilled water and dried in a vacuum oven at 60 °C.

Example4

Method of preparation ofpolyaniline encapsulating 10°/o graphene oxide (PNF10)

Polyaniline encapsulating 10% graphene oxide was prepared by in-situ interfacial polymerization method. Initially, 10 wt% of graphene oxide dispersed in distilled water was sonicated for 2 hours for exfoliation of graphene oxide layers after that ammonium persulfate (0.1 M) and HCl (1 M) was dissolved in aqueous graphene oxide dispersion while 0.1 M of aniline was dissolved in chloroform organic solvent. Now aqueous dispersion of graphene oxide was carefully added along the sides of the beaker to the organic solution to form a clear interface and then beaker was put into an ice bath. The polymerization reaction occurred at the interface of the aqueous-organic layers; after
12 hours of reaction the aqueous phase containing polyaniline was carefully separated from the organic phase. The aqueous phase was filtered, washed with distilled water and dried in a vacuum oven at 60 °C.

Example 5

EMI shielding effectiveness of polyaniline and polyaniline graphene composites

Agilent's vector network analyzer (VNA) N5230C PNA&L 10 MHz&40 GHz was used for EMI shielding measurements in X band frequency range (8.2-12.4 GHz). The samples were pressed into rectangular pellets of standard Ku-band dimensios using hydraulic press at the pressure of 5 tons. Figure 3 represents the variation of EMI shielding

effectiveness of the polyaniline (PNF) and polyanilinefgraphene oxide composites PNFS and PNF10 as a function of frequency. The total EMI shielding effectiveness of graphene oxide, PNF, PNFS and PNF10 observed was 10.06, 23.88, 37.13 and 19.03 dB, respectively. The maximu•m EMI shielding effectiveness of 37.13 dB was obtained with composite containing 5 wt% graphene oxide. The high value of shielding effectiveness of PNFS was supported by the high values of dielectric attributes as shown in the figure
8. These values are due to the amount of polarization in the material which depends on ionic, electronic, orientation, and space charge polarization. The total shielding effectiveness of the composites is resolved into shielding effectiveness due to absorption loss (SEA) and shielding effectiveness due to reflection loss (SER) as shown in figure 4 and S, respectively. It is clearly observed from the figure that the contributions to the shielding effectiveness values mainly come from the absorption loss mechanism
rather than reflection loss mechanism.

We claim:

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1. A method for the preparation of conducting polymer polyaniline encapsulated

with graphene oxide filler material. Measurement of scattering parameters for the calculations of EMI shielding effectiveness of the polyaniliejgraphene oxide
composites. The method comprises:
2. The incorporation of different wt% of graphene oxide to the polyaniline matrix. (a) 0.1 M aniline was dissolved in chloroform solvent to form organic phase.
(b) 0.1 M oxidant ammonium persulfate was dissolved in 1 M HCl solution to form.
(c) Aqueous phase was added to the organic phase carefully along the side of

the beaker and put into an ice bath initiate polymerization of aniline.

(d) After 12 hours of polymerization the aqueous phase . was carefully separated from the organic phase which was filtered, washed with distilled water and dried in vacuum oven.
(e) EMI shielding effectiveness was measured by calculating scattering parameters using vector network analyzer.
3. A process as claimed in claim 1•wherein the polymer chosen to make conducting composite was polyaniline and the alike.
4. A process as claimed in claims 1-3, wherein the filler material chosen was graphene oxide and alike.
5. A process as claimed in claims 1-3, wherein the graphite filler used was 5, and 10 wt% w.r.t. the aniline weight.
6. A process as claimed in claims 1-3, wherein the aniline monomer used was 0.1M, was dissolved in organic solvent chloroform.
7. A process as claimed in claims 1-3, wherein the oxidant ammonium persulfate used was 0.1M, was dissolved in 1M HCl aqueous solution.
8. A process as claimed in claims 1-7, wherein the polyanilinejgraphene oxide
composite were evaluated for EMI shielding effectiveness measurements by vector network analyzer (Agilent N5230C PNA