FIELD OF INVENTION:
[001] The present subject matter relates to conducting polymer-carbon allotropes 5 based composites for shielding electromagnetic interference (EMI), and in particular, to composites comprising a conducting polymer, i.e., Polypyrrole and carbon allotropes as substrates with a surfactant as dopant agent. The present subject matter relates to development of high EMI shielding effectiveness materials with advantages of reduced weight, improved corrosion resistant and good electrical conductivity. 10 These conducting polymer based composites find applications of electromagnetic interference shielding in Ku-band.
BACKGROUND OF INVENTION:
[002] With the development of powerful electronic and electrical equipments, EMI shielding becomes a significant factor for proper functioning of equipments and in the 15 prevention of human health hazards. The materials generally used for shielding includes metals and metallic composites. But they are associated with several disadvantages like heavy weight, corrosion, and expensive processing techniques. Conducting polymer coated carbon allotropes composites presents an alternative for EMI shielding because of light weight, anti-corrosion, excellent conductivity and 20 environmental stability. Conducting polymer coated carbon allotropes composites are lightweight; better corrosion resistant, having high electrical conductivity. These exciting features of conducting polymer coated carbon allotropes composites make it a strong alternate to replace metal based EMI shielding structures.
[003] Following are the works done so far in the field of conductive polymers based 25 materials for protective EMI shielding:
[004] US 6870092B2 (Methods and apparatus for EMI shielding)
3
[005] In this patent details have been given with respect to methods and apparatus for improving the resiliency and airflow through a honeycomb air vent filter while providing EMI shielding. In one embodiment, the honeycomb can be manufactured from a dielectric (e.g., plastic) substrate to provide improved resistance to deformation as compared to conventional aluminum honeycomb. The dielectric 5 honeycomb substrate is metallized to provide EMI shielding capability. The metallized honeycomb substrate is cut slightly oversize to fit an opening in an electronic enclosure, which results in elastic deformation of resilient perimeter spring fingers that are used to hold the metallized dielectric honeycomb in place and provide electrical conductivity between the metallized dielectric substrate and the enclosure, 10 thereby eliminating the use of a frame. In another embodiment, additional conductive layers can be added to the metallized dielectric honeycomb. In yet another embodiment, the metallized dielectric honeycomb substrate can be utilized in a framed configuration to provide improved durability.
[006] US 20100188833A1 (Electromagnetic interference shielding structure 15 including carbon nanotube or nanofiber films and methods)
[007] The patent relates to designing of a composite material for electromagnetic interference shielding. The composite material comprises a stack including at least two electrically conductive nanoscale fiber films, which are spaced apart from one another by at least one insulating gap positioned between the at least two nanoscale 20 fiber films. The stack is effective to provide a substantial multiple internal reflection effect. An electromagnetic interference shielded apparatus and a method for shielding an electrical circuit from electromagnetic interference is provided.
[008] CN103266542A (Preparation method of carbon nanotube electromagnetic wave shielding paper) 25
[009] The invention relates to a method for preparing carbon nanotube electromagnetic wave shielding paper, which comprises the following steps: (a) adding a carbon nanotube into solvent, then adding resin and surfactant, performing dispersion treatment, and uniformly stirring, thus preparing carbon nanotube ink; and
4
(b) by taking the carbon nanotube ink as a raw material, designing a printed mesh line pattern according to the requirements for shielding performance, printing carbon nanotube electromagnetic wave shielding paper in an ink jet printing mode, drying, and finishing, wherein the carbon nanotube ink contains 10-95wt% of solvent, 0.1-20wt% of carbon nanotube, 2-50wt% of resin and 0.1-5wt% of surfactant; the line 5 width W1 of the mesh line pattern is 1-500mu m, the width W2 of the blank part is 1-500mu m, and the area ratio of the mesh lines is 20-99.9%. The method provided by the invention can be used for preparing electromagnetic wave shielding paper, and has the advantages of simple process and raw material saving; and the shielding paper is wide in shielding wave band, adjustable in property, portable and easy to use, and 10 can be widely used hopefully.
[0010] US20100000770A1 (Conducting Nanotubes or Nanostructures Based Composites, Method of Making Them and Applications)
[0011] The patent relates to the preparation of an electromagnetic interference (EMI) shielding material which includes a matrix of a dielectric or partially conducting 15 polymer, such as foamed polystyrene, with carbon nanotubes or other nanostructures dispersed therein in sufficient concentration to make the material electrically conducting. The composite is formed by dispersing the nanotube material in a solvent in which the dielectric or partially conducting polymer is soluble and mixing the resulting suspension with the dielectric or partially conducting polymer. A foaming 20 agent can be added to produce a lightweight foamed material. An organometallic compound can be added to enhance the conductivity further by decomposition into a metal phase.
[0012] CN104093787A (Resin composition for EMI Shielding, comprising carbon hydride composite) 25
[0013] The patent gives details of resin composition for electromagnetic interference shielding. More particularly, provided is a resin composition having superior dispersibility and impact relaxation and high conductivity, the resin comprising: (a) 100 parts by weight of a resin; based on 100 parts by weight of the resin, (b) 0.1 to 15
5
parts by weight of a carbon nanotube surface-modified in a condition of the absence of oxidant; and (c) 1 to 40 parts by weight of a carbon compound, a metal, a metal compound, or a mixture thereof. The resin composition for electromagnetic interference shielding, comprising a carbon hydride composite, is specifically useful in an electronic control unit material for weight reduction of car, and thus can be 5 replaced with a high-priced heavy metal material.
[0014] US20080057265A1 (Electromagnetic Interference Shielding Structure Including Carbon Nanotubes and Nanofibers)
[0015] The invention relates to designing electromagnetic interference (EMI) shielding structure and methods of making such structures are provided. In one case, 10 a method is provided for making a lightweight composite structure for electromagnetic interference shielding, including the steps of providing a nanoscale fiber film which comprises a plurality of nanoscale fibers; and combining the nanoscale fiber film with one or more structural materials to form a composite material which is effective as an electromagnetic interference shielding structure. In 15 another case, a method is provided for shielding a device which includes an electrical circuit from electromagnetic interference comprising the steps of providing a nanoscale fiber film which comprises a plurality of nanoscale fibers; and incorporating the nanoscale fiber film into an exterior portion of the device to shield an interior portion of the device from electromagnetic interference. 20
[0016] US20060241236A1 (Electromagnetic radiation attenuation)
[0017] The patent describes an electromagnetic radiation attenuating material or coating consistent with certain embodiments of the present invention uses a binding matrix with an operative quantity of electromagnetic radiation attenuating nano-particles suspended in the binding matrix, wherein, the electromagnetic radiation 25 attenuating nano-particles comprise onion-like-carbon (OLC) particles. In other embodiments, freestanding structures, aerosols and powders or suspensions contained within an enclosure provide EM or Radar absorption, particularly in the range of about 500 MHz to about 30 THz.
6
[0018] US7008563B2 (Polymer-wrapped single wall carbon nanotubes)
[0019] The present invention relates to new compositions of matter and articles of manufacture comprising SWNTs as nanometer scale conducting rods dispersed in an electrically-insulating matrix. These compositions of matter have novel and useful electrical, mechanical, and chemical properties including applications in antennas, 5 electromagnetic and electro-optic devices, and high-toughness materials. Other compositions of matter and articles of manufacture are disclosed, including polymer-coated and polymer wrapped single-wall nanotubes (SWNTs), small ropes of polymer-coated and polymer-wrapped SWNTs and materials comprising same. This composition provides one embodiment of the SWNT conducting-rod composite 10 mentioned above, and also enables creation of high-concentration suspensions of SWNTs and compatibilization of SWNTs with polymeric matrices in composite materials. This solubilization and compatibilization, in turn, enables chemical manipulation of SWNT and production of composite fibers, films, and solids comprising SWNTs. 15
[0020] WO1990009027A1 (Use of electrically conducting polymer composites)
[0021] The subject invention is direct towards novel use of a polymer composite as thermoplastic raw material for products with electrically conducting or semiconducting properties. In polymer composites known in the field electrically conducting fillers and polymers do not have thermoplastic properties and are 20 accordingly ill suited for thermoplastic processing of conducting and semiconducting products. It has now been invented that a polymer composite made up of an electrically nonconducting polymer matrix or polymer substrate, doped or undoped poly(3-substituted thiophene) and possibly plastics additives, is well suited as raw material for thermoplastics with conducting or semiconducting properties. The 25 invention is accordingly also directed towards antistatic and semiconducting applications, where good shielding against electromagnetic interference is required and applications where the discovered piezoelectric properties of this material can be used.
7
[0022] Accordingly, there is a need in the art to develop a Polypyrrole and carbon based EMI shielding effectiveness materials.
OBJECTIVE OF THE INVENTION:
[0023] The main objective of the present invention is to fabricate efficient conducting polymer deposited over different carbon allotropes composites for EMI shielding 5 application.
[0024] Another object of the present invention is to develop light weight, corrosion resistant, and easily process able materials with excellent shielding behaviour towards electromagnetic waves.
SUMMARY OF THE INVENTION: 10
[0025] The present invention relates to a process of fabricating conducting polymer, i.e., Polypyrrole deposited amine functionalized multiwalled carbon nanotubes, graphene and hybrid carbon assemblage (AMWCNTs+graphene) composites and their application in EMI shielding thereof. The method of prepare of Polypyrrole deposited amine functionalized multiwalled carbon nanotubes, graphene and hybrid 15 carbon assemblage (AMWCNTs+graphene) composites comprising steps of: Preparation of Sodium Lauryl Sulphate (SLS) doped Polypyrrole via simple chemical polymerization method by using ferric chloride (FeCl3) as oxidant in the reaction. Then, Preparation of Amine functionalized multi-walled carbon nano-tubes solution in organic solvent by Ultrasonicator. Addition of SLS doped conducting polymer to 20 the amine functionalized multiwalled carbon nanotube suspension and continous stirring of the mixer for six hours to prepare ACNTs@SLS-PPy composite. Similarly, SLS doped conducting polymer is mixed with graphene and Hybrid carbon assemblage via in-situ chemical polymerization method. Measuring the EMI shielding effectiveness of the composite samples by vector network analyzer system, 25 respectively.
[0026] In another embodiment of the invention, the dopant and oxidant chosen for above study was Sodium Lauryl sulphate (SLS) and Ferric Chloride (FeCl3). In
8
another embodiment of the invention, the carbon allotropes taken are amine functionalized multiwalled carbon nanotubes, graphene and hybrid carbon assemblage graphene (AMWCNTs+graphene) act as substrates for deposition of conducting polymer. Further, the solvent of polymerization choose is 1MHCl+20% Methanol Solution. The temperature of the polymerization condition was kept 5 between 0-5°C. The dopant to monomer and oxidant to monomer ratio was kept 1:1 and 2:1. The polymerisation reaction time was kept between 6-8 hours.
[0027] The prepared composites were washed by deionized water and dried at 50 °C. at the end, measurement of the EMI shielding effectiveness of the composite samples 10 by using a vector network analyzer (VNA E8263B Agilent Technologies) by placing pellet inside a copper sample holder connected between the wave-guide flanges of the network analyzer in the Ku-band (12.4–18.0 GHz) waveguide.
[0028] In order to further understand the characteristics and technical contents of the present subject matter, a description relating thereto will be made with reference to 15 the accompanying drawings. However, the drawings are illustrative only but not used to limit scope of the present subject matter.
BRIEF DESCRIPTIONS OF THE DRAWINGS
[0029] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for 20 limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some 25 embodiments of system or methods in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
9
[0030] Fig. 1: Schematic illustration of Preparation of Sodium Lauryl Sulphate (SLS) doped Polypyrrole (PPy)-Hybrid carbon assemblage (HCA) composite, in accordance with the present subject matter;
[0031] Fig. 2 illustrates method of preparation of Preparation of Sodium Lauryl Sulphate (SLS) doped Polypyrrole (PPy)-Hybrid carbon assemblage (HCA) 5 composite in reference to figure 1, in accordance with the present subject matter
[0032] Fig. 3: illustrates XRD patterns of (a) SLS-PPy (b) ACNT@SLS-PPy (c) GR@SLS-PPy (d) HCA@SLS-PPy, in accordance with the present subject matter;
[0033] Fig. 4: illustrates FTIR spectra of (a) SLS-PPy (b) ACNT@SLS-PPy (c) GR@SLS-PPy (d) HCA@SLS-PPy, in accordance with the present subject matter; 10
[0034] Fig. 5: illustrates FESEM images of (a) SLS-PPy (b) ACNT@SLS-PPy (c) GR@SLS-PPy (d) HCA@SLS-PPy, in accordance with the present subject matter;
[0035] Fig. 6: illustrates Variation of total shielding effectiveness with frequency, in accordance with the present subject matter;
[0036] Fig. 7: Shielding effectiveness due to absorption loss, in accordance with the 15 present subject matter; and
[0037] Fig. 8: Shielding effectiveness due to reflection loss, in accordance with the present subject matter.
[0038] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the 20 following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0039] At the very outset of the detailed description, it may be understood that the 25 ensuing description only illustrates a particular form of this invention. However, such a particular form is only exemplary embodiment, and without intending to imply any limitation on the scope of this invention. Accordingly, the description is to be
10
understood as an exemplary embodiment and teaching of invention and not intended to be taken restrictively.
[0040] The present subject matter relates to a process for fabrication efficient conducting polymer deposited over different carbon allotropes composites for EMI shielding application. The process comprising steps of: Preparation of Amine 5 functionalized multiwalled carbon nanotubes solution in organic solvent by Ultrasonicator. Further, addition of SLS doped conducting polymer to the amine functionalized multiwalled carbon nanotube suspension and continous stirring of the mixer for six hours to prepare ACNTs@SLS-PPy composite. After homogenization, the polymerization is performed by adding FeCl3 into the prepared ACNTs@SLS-10 PPy composite. In the polymerization method, SLS doped conducting polymer is mixed with graphene and Hybrid carbon assemblage is formed. Which further, filtered washed and vaccum dried to obtain the composite powder. Once the composite powder is obtained, the EMI shielding effectiveness of the composite samples is measured by vector network analyzer system. 15
[0041] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art 20 that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the 25 inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better
11
understood from the following description when considered in connection with the accompanying figures.
[0042] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus 5 be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0043] The present subject matter relates generally to electromagnetic (EM) radiation absorbing composites containing conducting polymer and carbon allotropes. These 10 prepared composites found enormous applications as EM shielding materials, for example, EM-sensitive electronic equipment, stealth vehicles, aircraft, etc., having low radar profiles, protection of electronic components from interference from one another on circuit boards, protection of computer equipment from emitting RF radiation causing interference to navigation systems, medical life support systems, 15 etc. Without being bound by theory, it is believed that in composites of this invention, EM shielding is achieved through absorption of radiation rather than reflection.
[0044] Figure 1 describes the process of fabrication of efficient conducting polymer deposited over different carbon allotropes composites for EMI shielding application. Further, figure 2 illustrates the steps of the figure 1. As shown in the figure 2 at step 20 202, Amine functionalized multiwalled carbon nanotubes solution is prepared using graphene in organic solvent by Ultrasonicator for 2 hours. In the Ultrasonicator forms the Hybrid Carbon Assemblage using the Amine CNTs and the graphene. The Hybrid Carbon Assemblage is homogenized by sonication in the Ultrasonicator.
[0045] The Sodium Lauryl Sulphate (SLS) doped Polypyrrole is prepared via simple 25 chemical polymerization method by using ferric chloride (FeCl3) as oxidant in the reaction. In the next step 204, SLS doped conducting polymer is added to the amine functionalized multiwalled carbon nanotube suspension and continous stirring of the mixer for six hours to prepare ACNTs@SLS-PPy composite. In the next step 206, the
12
SLS doped conducting polymer is mixed with graphene and Hybrid carbon assemblage via in-situ chemical polymerization method by adding FeCl
3. In the step 208, the SLS doped polypyrrole Hybrid carbon assemblage (HCA) is formed. The SLS doped polypyrrole Hybrid carbon assemblage (HCA) is filtered, washed and dried in the vacuum to obtain composite powder for pellets and EMI shielding 5 applications.
[0046] After obtaining the composite powder of the SLS doped polypyrrole Hybrid carbon assemblage (HCA), the composite powder is transformed into the pellets using hydraulic press. The pellets of the composite powder are tested using vector network analyzer (VNA). The measurement of the EMI shielding effectiveness of the 10 composite samples by using a vector network analyzer (VNA E8263B Agilent Technologies) by placing pellet inside a copper sample holder connected between the wave-guide flanges of the network analyzer in the Ku-band (12.4–18.0 GHz) waveguide. Further, the test results are given in the table 1.
[0047] Fig. 3: illustrates XRD patterns of (a) SLS-PPy (b) ACNT@SLS-PPy (c) 15 GR@SLS-PPy (d) HCA@SLS-PPy, in accordance with the present subject matter.
[0048] Fig. 4: illustrates FTIR spectra of (a) SLS-PPy (b) ACNT@SLS-PPy (c) GR@SLS-PPy (d) HCA@SLS-PPy, in accordance with the present subject matter.
[0049] Fig. 5: illustrates FESEM images of (a) SLS-PPy (b) ACNT@SLS-PPy (c) GR@SLS-PPy (d) HCA@SLS-PPy, in accordance with the present subject matter. 20
[0050] Fig. 6: illustrates Variation of total shielding effectiveness with frequency, in accordance with the present subject matter.
[0051] Fig. 7: Shielding effectiveness due to absorption loss, in accordance with the present subject matter.
[0052] Fig. 8: Shielding effectiveness due to reflection loss, in accordance with the 25 present subject matter.
[0053] The following examples are given to illustrate the process of the present invention and should not be construed to limit the scope of the present invention:
13
Example 1
Synthesis of Sodium lauryl sulphate doped Poypyrrole coated over three different carbon allotropes substrates:
[0054] The Sodium Lauryl Sulphate doped polypyrrole-amine functionalized carbon nanotube, graphene and hybrid carbon assemblage (AMWCNTs+graphene) 5 composites were prepared via chemical oxidative polymerization of pyrrole dispersed onto carbon nanotubes, graphene and hybrid carbon assemblage. The molar concentration of pyrrole was 0.025M and the resulting composites were designated as (a) SLS-PPy (b) ACNT@SLS-PPy (c) GR@SLS-PPy and (d) HCA@SLS-PPy respectively. A typical preparation protocol for the preparation of composites was 10 described as following. The freshly distilled pyrrole (0.025M) was injected into a suspension of different carbon substrates (0.1g) in 20% methanol solution. The suspension was ultrasonicated for 120 minutes prior to cooling in an ice bath for uniform dispersion. The reaction was then slowly added with an equivalent Sodium Lauryl Sulphate (0.025M) and FeCl3 (0.05M) solution and allowed to proceed at 0–15 5◦C for 24 h. After filtration, the title composite was washed subsequently with methanol and water several times, and the product was dried at overnight at 60◦C in vacuum. All as-prepared composites were kept in cool place for followed characterization. Methanol washing is desirable for the removal of oligomeric impurities. 20
Example 2
Synthesis of Polypyrrole and Sodium dodecyl benzene sulphonate doped Poypyrrole coated over three different carbon substrates:
[0055] The Polypyrrole and polypyrrole-amine functionalized multiwalled carbon nanotube, graphene and hybrid carbon assemblage (AMWCNTs+graphene) 25 composites were prepared via in-situ polymerization of pyrrole dispersed onto carbon nanotubes, graphene and hybrid carbon assemblage. The molar concentration of pyrrole was 0.025M and the resulting composites were designated as PPy-CNT, PPy-
14
GR and PPy-HC respectively. A typical preparation protocol for the preparation of composites was described as following. The freshly distilled pyrrole (0.025M) was injected into a suspension of different carbon substrates (0.1g) in 20% methanol solution. The suspension was ultrasonicated for 40-60 min prior to cooling in an ice bath for uniform dispersion. The reaction was then slowly added with an equivalent 5 FeCl
3 (0.49 g in 1 M HCl) solution and allowed to proceed at 0–5◦C for 24 h. After filtration, the title composite was washed subsequently with ethanol and water several times, and the product was dried at overnight at 60◦C in vacuum. All as-prepared composites were kept in cool place for followed characterization. Sodium dodecyl benzene sulfonate (NaDBS) (0.025M) doped polypyrrole and composites were 10 prepared with similar method as mentioned in above protocol. It is observed that combination of FeCl3 and anionic surfactant NaDBS enhanced the conductivity as well as increased yield of resultant polymer.
Example 3
Synthesis of 5-Sulfoisophthalic acid monolithium salt doped PPy: 15
[0056] In a typical reaction, 0.05 mol (12.6 g) of LiSiPA and 0.05 mol (3.35 g) of pyrrole was mixed and dissolved in 100 mL distilled water using magnetic stirrer. In another vessel, aqueous solution of ferric chloride was prepared by dissolving 0.1M (16.22 g) of FeCl3 in 200 mL of water. Polymerization was initiated by drop wise addition of FeCl3 solution to aqueous solution of pyrrole/LiSiPA and allowed to stir 20 continuously for 6 h. Temperature of the reaction mixture was kept around 0-6 °C. The polymer thus obtained was separated by filtration and washed repeatedly with distilled water till the pH of the filtrate became neutral. The precipitated polymer was then washed with methanol to remove the oligomers followed by drying under vacuum till constant weight. The dried mass was then crushed to obtain the powder of 25 doped polymer.
Example 4
Synthesis of PPy/MWCNT Composites:
15
[0057] Synthesis of PPy/MWCNT composites having varying amounts of MWCNTs were prepared by in situ polymerization of pyrrole using the same procedure by keeping amount of pyrrole, LiSiPA, and FeCl3 same as in the preparation of PPy. For the preparation of composites, requisite amount of MWCNTs was dispersed in the aqueous solution of LiSiPA and sonicated for 2 h. After sonication, pyrrole was 5 added to this solution and mixed using magnetic stirrer. The polymerization was then carried out by adding aqueous solution of FeCl3. PPy prepared in the presence of 0, 1, 2, 3, 4, and 5 weight percent of MWCNTs (with respect to monomer weight).
[0058] Embodiments of the present subject matter:
[0059] In the present subject matter, the monomer chosen for study is pyrrole. 10
[0060] In another embodiment of the present subject matter, the dopant and oxidant chosen for above study was Sodium Lauryl sulphate (SLS) and Ferric Chloride (FeCl3).
[0061] In another embodiment of the present subject matter, the carbon allotropes taken are amine functionalized multiwalled carbon nanotubes, graphene and hybrid 15 carbon assemblage graphene (AMWCNTs+graphene) act as substrates for deposition of conducting polymer.
[0062] In another embodiment of the present subject matter, the solvent of polymerization choose is 1MHCl+20% Methanol Solution.
[0063] In another embodiment of the present subject matter, the temperature of the 20 polymerization condition was kept between 0-5°C.
[0064] In another embodiment of the present subject matter, dopant to monomer and oxidant to monomer ratio was kept 1:1 and 2:1.
[0065] In another embodiment of the present subject matter, the polymerisation reaction time was kept between 6-8 hours. 25
[0066] In another embodiment of the present subject matter, the prepared composites were washed by deionized water and dried at 50 °C.
[0067] In another embodiment of the present subject matter, measurement of the EMI shielding effectiveness of the composite samples by using a vector network analyzer
16
(VNA E8263B Agilent Technologies) by placing pellet inside a copper sample holder connected between the wave-guide flanges of the network analyzer in the Ku-band (12.4–18.0 GHz) waveguide
[0068] Table 1: EMI shielding data of SLS-PPy and Composites
Table 1 5
S. No.
Sample
SLS
Pyrrole
Amine CNTs
Graphene
SET
(dB)
SEA
(dB)
SER
(dB)
1.
SLS-PPy
0.025M
0.025M
---
---
30.53
25.05
5.48
2.
ACNT@SLS-PPy
0.025M
0.025M
0.1g
---
39.07
30.39
8.68
3.
GR@SLS-PPy
0.025M
0.025M
---
0.1g
50.10
41.70
8.30
4.
HCA@SLS-PPy
0.025M
0.025M
0.1g
0.1g
80.00
66.00
14.00
[0069] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. 10 Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.

Claims:We claim:
1. A process for fabricating Polypyrrole polymer deposited over different carbon allotropes composites for EMI shielding application, the process comprising steps of:
a) Synthesizing Polypyrrole with SLS as dopant deposited over carbon allotropes as substrate, wherein SLS and FeCl3 used as dopant and oxidant during the oxidative polymerization of the polyprrole monomer;
b) Preparation of Hybrid Carbon Assemblage using the Amine CNTs and the graphene using ultrasonication;
c) Formation of SLS doped polypyrrole deposited Hybrid carbon assemblage (HCA) composite by adding SLS doped Polypyrrole and FeCl3 in-situ chemical polymerization; and
d) Obtaining SLS doped polypyrrole deposited Hybrid carbon assemblage (HCA) composite after filtration, washing and vacuum drying.

2. The process as claimed in claim 1, wherein the polymer selected for deposition over carbon allotropes substrate is Polypyrrole and the like.

3. The process as claimed in claim 1, wherein the medium of polymerization is aqueous with 1M HCl+20% Methanol solution with de-ionized water used as solvent.
4. The process as claimed in claim 1, wherein the dopant and oxidant is Sodium lauryl sulphate (SLS) and Ferric Chloride (FeCl3) during the polymerization of monomer polypyrrole and the like.
5. The process as claimed in claim 4, wherein the dopant to poylmer and the oxidant to polymer ratio are 1:1 and 2:1.

6. The process as claimed in claim 1, wherein the carbon allotropes substrates are amine functionalized Carbon Nanotubes, Graphene, and Hybrid Carbon Assemblage.

7. The process as claimed in claim 1, wherein temperature of the polymerization condition is in between 0-6°C and polymerization reaction time is in between 5-8 hours.

8. The process as claimed in claims 1, wherein the prepared samples tested by vector network analyzer (VNA E8263B Agilent Technologies).

9. The process as claimed in claim 1, wherein shielding performance of prepared composites (15.8×7.9×1.5 mm Dimensions) evaluated by placing pellet inside a copper sample holder connected between the wave-guide flanges of the network analyzer in the Ku-band (12.4–18.0 GHz) waveguide.

10. The process as claimed in claim 1, wherein the obtained composite are dried at overnight at 60oC vacuum.
, Description:DEVELOPMENT OF CONDUCTING POLYMER-CARBON ALLOTROPES COMPOSITES AS EMI SHIELDING MATERIAL

FIELD OF INVENTION:
[001] The present subject matter relates to conducting polymer-carbon allotropes based composites for shielding electromagnetic interference (EMI), and in particular, to composites comprising a conducting polymer, i.e., Polypyrrole and carbon allotropes as substrates with a surfactant as dopant agent. The present subject matter relates to development of high EMI shielding effectiveness materials with advantages of reduced weight, improved corrosion resistant and good electrical conductivity. These conducting polymer based composites find applications of electromagnetic interference shielding in Ku-band.
BACKGROUND OF INVENTION:
[002] With the development of powerful electronic and electrical equipments, EMI shielding becomes a significant factor for proper functioning of equipments and in the prevention of human health hazards. The materials generally used for shielding includes metals and metallic composites. But they are associated with several disadvantages like heavy weight, corrosion, and expensive processing techniques. Conducting polymer coated carbon allotropes composites presents an alternative for EMI shielding because of light weight, anti-corrosion, excellent conductivity and environmental stability. Conducting polymer coated carbon allotropes composites are lightweight; better corrosion resistant, having high electrical conductivity. These exciting features of conducting polymer coated carbon allotropes composites make it a strong alternate to replace metal based EMI shielding structures.
[003] Following are the works done so far in the field of conductive polymers based materials for protective EMI shielding:
[004] US 6870092B2 (Methods and apparatus for EMI shielding)
[005] In this patent details have been given with respect to methods and apparatus for improving the resiliency and airflow through a honeycomb air vent filter while providing EMI shielding. In one embodiment, the honeycomb can be manufactured from a dielectric (e.g., plastic) substrate to provide improved resistance to deformation as compared to conventional aluminum honeycomb. The dielectric honeycomb substrate is metallized to provide EMI shielding capability. The metallized honeycomb substrate is cut slightly oversize to fit an opening in an electronic enclosure, which results in elastic deformation of resilient perimeter spring fingers that are used to hold the metallized dielectric honeycomb in place and provide electrical conductivity between the metallized dielectric substrate and the enclosure, thereby eliminating the use of a frame. In another embodiment, additional conductive layers can be added to the metallized dielectric honeycomb. In yet another embodiment, the metallized dielectric honeycomb substrate can be utilized in a framed configuration to provide improved durability.
[006] US 20100188833A1 (Electromagnetic interference shielding structure including carbon nanotube or nanofiber films and methods)
[007] The patent relates to designing of a composite material for electromagnetic interference shielding. The composite material comprises a stack including at least two electrically conductive nanoscale fiber films, which are spaced apart from one another by at least one insulating gap positioned between the at least two nanoscale fiber films. The stack is effective to provide a substantial multiple internal reflection effect. An electromagnetic interference shielded apparatus and a method for shielding an electrical circuit from electromagnetic interference is provided.
[008] CN103266542A (Preparation method of carbon nanotube electromagnetic wave shielding paper)
[009] The invention relates to a method for preparing carbon nanotube electromagnetic wave shielding paper, which comprises the following steps: (a) adding a carbon nanotube into solvent, then adding resin and surfactant, performing dispersion treatment, and uniformly stirring, thus preparing carbon nanotube ink; and (b) by taking the carbon nanotube ink as a raw material, designing a printed mesh line pattern according to the requirements for shielding performance, printing carbon nanotube electromagnetic wave shielding paper in an ink jet printing mode, drying, and finishing, wherein the carbon nanotube ink contains 10-95wt% of solvent, 0.1-20wt% of carbon nanotube, 2-50wt% of resin and 0.1-5wt% of surfactant; the line width W1 of the mesh line pattern is 1-500mu m, the width W2 of the blank part is 1-500mu m, and the area ratio of the mesh lines is 20-99.9%. The method provided by the invention can be used for preparing electromagnetic wave shielding paper, and has the advantages of simple process and raw material saving; and the shielding paper is wide in shielding wave band, adjustable in property, portable and easy to use, and can be widely used hopefully.
[0010] US20100000770A1 (Conducting Nanotubes or Nanostructures Based Composites, Method of Making Them and Applications)
[0011] The patent relates to the preparation of an electromagnetic interference (EMI) shielding material which includes a matrix of a dielectric or partially conducting polymer, such as foamed polystyrene, with carbon nanotubes or other nanostructures dispersed therein in sufficient concentration to make the material electrically conducting. The composite is formed by dispersing the nanotube material in a solvent in which the dielectric or partially conducting polymer is soluble and mixing the resulting suspension with the dielectric or partially conducting polymer. A foaming agent can be added to produce a lightweight foamed material. An organometallic compound can be added to enhance the conductivity further by decomposition into a metal phase.
[0012] CN104093787A (Resin composition for EMI Shielding, comprising carbon hydride composite)
[0013] The patent gives details of resin composition for electromagnetic interference shielding. More particularly, provided is a resin composition having superior dispersibility and impact relaxation and high conductivity, the resin comprising: (a) 100 parts by weight of a resin; based on 100 parts by weight of the resin, (b) 0.1 to 15 parts by weight of a carbon nanotube surface-modified in a condition of the absence of oxidant; and (c) 1 to 40 parts by weight of a carbon compound, a metal, a metal compound, or a mixture thereof. The resin composition for electromagnetic interference shielding, comprising a carbon hydride composite, is specifically useful in an electronic control unit material for weight reduction of car, and thus can be replaced with a high-priced heavy metal material.
[0014] US20080057265A1 (Electromagnetic Interference Shielding Structure Including Carbon Nanotubes and Nanofibers)
[0015] The invention relates to designing electromagnetic interference (EMI) shielding structure and methods of making such structures are provided. In one case, a method is provided for making a lightweight composite structure for electromagnetic interference shielding, including the steps of providing a nanoscale fiber film which comprises a plurality of nanoscale fibers; and combining the nanoscale fiber film with one or more structural materials to form a composite material which is effective as an electromagnetic interference shielding structure. In another case, a method is provided for shielding a device which includes an electrical circuit from electromagnetic interference comprising the steps of providing a nanoscale fiber film which comprises a plurality of nanoscale fibers; and incorporating the nanoscale fiber film into an exterior portion of the device to shield an interior portion of the device from electromagnetic interference.
[0016] US20060241236A1 (Electromagnetic radiation attenuation)
[0017] The patent describes an electromagnetic radiation attenuating material or coating consistent with certain embodiments of the present invention uses a binding matrix with an operative quantity of electromagnetic radiation attenuating nano-particles suspended in the binding matrix, wherein, the electromagnetic radiation attenuating nano-particles comprise onion-like-carbon (OLC) particles. In other embodiments, freestanding structures, aerosols and powders or suspensions contained within an enclosure provide EM or Radar absorption, particularly in the range of about 500 MHz to about 30 THz.
[0018] US7008563B2 (Polymer-wrapped single wall carbon nanotubes)
[0019] The present invention relates to new compositions of matter and articles of manufacture comprising SWNTs as nanometer scale conducting rods dispersed in an electrically-insulating matrix. These compositions of matter have novel and useful electrical, mechanical, and chemical properties including applications in antennas, electromagnetic and electro-optic devices, and high-toughness materials. Other compositions of matter and articles of manufacture are disclosed, including polymer-coated and polymer wrapped single-wall nanotubes (SWNTs), small ropes of polymer-coated and polymer-wrapped SWNTs and materials comprising same. This composition provides one embodiment of the SWNT conducting-rod composite mentioned above, and also enables creation of high-concentration suspensions of SWNTs and compatibilization of SWNTs with polymeric matrices in composite materials. This solubilization and compatibilization, in turn, enables chemical manipulation of SWNT and production of composite fibers, films, and solids comprising SWNTs.
[0020] WO1990009027A1 (Use of electrically conducting polymer composites)
[0021] The subject invention is direct towards novel use of a polymer composite as thermoplastic raw material for products with electrically conducting or semiconducting properties. In polymer composites known in the field electrically conducting fillers and polymers do not have thermoplastic properties and are accordingly ill suited for thermoplastic processing of conducting and semiconducting products. It has now been invented that a polymer composite made up of an electrically nonconducting polymer matrix or polymer substrate, doped or undoped poly(3-substituted thiophene) and possibly plastics additives, is well suited as raw material for thermoplastics with conducting or semiconducting properties. The invention is accordingly also directed towards antistatic and semiconducting applications, where good shielding against electromagnetic interference is required and applications where the discovered piezoelectric properties of this material can be used.
[0022] Accordingly, there is a need in the art to develop a Polypyrrole and carbon based EMI shielding effectiveness materials.
OBJECTIVE OF THE INVENTION:
[0023] The main objective of the present invention is to fabricate efficient conducting polymer deposited over different carbon allotropes composites for EMI shielding application.
[0024] Another object of the present invention is to develop light weight, corrosion resistant, and easily process able materials with excellent shielding behaviour towards electromagnetic waves.
SUMMARY OF THE INVENTION:
[0025] The present invention relates to a process of fabricating conducting polymer, i.e., Polypyrrole deposited amine functionalized multiwalled carbon nanotubes, graphene and hybrid carbon assemblage (AMWCNTs+graphene) composites and their application in EMI shielding thereof. The method of prepare of Polypyrrole deposited amine functionalized multiwalled carbon nanotubes, graphene and hybrid carbon assemblage (AMWCNTs+graphene) composites comprising steps of: Preparation of Sodium Lauryl Sulphate (SLS) doped Polypyrrole via simple chemical polymerization method by using ferric chloride (FeCl3) as oxidant in the reaction. Then, Preparation of Amine functionalized multi-walled carbon nano-tubes solution in organic solvent by Ultrasonicator. Addition of SLS doped conducting polymer to the amine functionalized multiwalled carbon nanotube suspension and continous stirring of the mixer for six hours to prepare ACNTs@SLS-PPy composite. Similarly, SLS doped conducting polymer is mixed with graphene and Hybrid carbon assemblage via in-situ chemical polymerization method. Measuring the EMI shielding effectiveness of the composite samples by vector network analyzer system, respectively.
[0026] In another embodiment of the invention, the dopant and oxidant chosen for above study was Sodium Lauryl sulphate (SLS) and Ferric Chloride (FeCl3). In another embodiment of the invention, the carbon allotropes taken are amine functionalized multiwalled carbon nanotubes, graphene and hybrid carbon assemblage graphene (AMWCNTs+graphene) act as substrates for deposition of conducting polymer. Further, the solvent of polymerization choose is 1MHCl+20% Methanol Solution. The temperature of the polymerization condition was kept between 0-5°C. The dopant to monomer and oxidant to monomer ratio was kept 1:1 and 2:1. The polymerisation reaction time was kept between 6-8 hours.

[0027] The prepared composites were washed by deionized water and dried at 50 °C. at the end, measurement of the EMI shielding effectiveness of the composite samples by using a vector network analyzer (VNA E8263B Agilent Technologies) by placing pellet inside a copper sample holder connected between the wave-guide flanges of the network analyzer in the Ku-band (12.4–18.0 GHz) waveguide.
[0028] In order to further understand the characteristics and technical contents of the present subject matter, a description relating thereto will be made with reference to the accompanying drawings. However, the drawings are illustrative only but not used to limit scope of the present subject matter.
BRIEF DESCRIPTIONS OF THE DRAWINGS
[0029] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0030] Fig. 1: Schematic illustration of Preparation of Sodium Lauryl Sulphate (SLS) doped Polypyrrole (PPy)-Hybrid carbon assemblage (HCA) composite, in accordance with the present subject matter;
[0031] Fig. 2 illustrates method of preparation of Preparation of Sodium Lauryl Sulphate (SLS) doped Polypyrrole (PPy)-Hybrid carbon assemblage (HCA) composite in reference to figure 1, in accordance with the present subject matter
[0032] Fig. 3: illustrates XRD patterns of (a) SLS-PPy (b) ACNT@SLS-PPy (c) GR@SLS-PPy (d) HCA@SLS-PPy, in accordance with the present subject matter;
[0033] Fig. 4: illustrates FTIR spectra of (a) SLS-PPy (b) ACNT@SLS-PPy (c) GR@SLS-PPy (d) HCA@SLS-PPy, in accordance with the present subject matter;
[0034] Fig. 5: illustrates FESEM images of (a) SLS-PPy (b) ACNT@SLS-PPy (c) GR@SLS-PPy (d) HCA@SLS-PPy, in accordance with the present subject matter;
[0035] Fig. 6: illustrates Variation of total shielding effectiveness with frequency, in accordance with the present subject matter;
[0036] Fig. 7: Shielding effectiveness due to absorption loss, in accordance with the present subject matter; and
[0037] Fig. 8: Shielding effectiveness due to reflection loss, in accordance with the present subject matter.
[0038] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0039] At the very outset of the detailed description, it may be understood that the ensuing description only illustrates a particular form of this invention. However, such a particular form is only exemplary embodiment, and without intending to imply any limitation on the scope of this invention. Accordingly, the description is to be understood as an exemplary embodiment and teaching of invention and not intended to be taken restrictively.
[0040] The present subject matter relates to a process for fabrication efficient conducting polymer deposited over different carbon allotropes composites for EMI shielding application. The process comprising steps of: Preparation of Amine functionalized multiwalled carbon nanotubes solution in organic solvent by Ultrasonicator. Further, addition of SLS doped conducting polymer to the amine functionalized multiwalled carbon nanotube suspension and continous stirring of the mixer for six hours to prepare ACNTs@SLS-PPy composite. After homogenization, the polymerization is performed by adding FeCl3 into the prepared ACNTs@SLS-PPy composite. In the polymerization method, SLS doped conducting polymer is mixed with graphene and Hybrid carbon assemblage is formed. Which further, filtered washed and vaccum dried to obtain the composite powder. Once the composite powder is obtained, the EMI shielding effectiveness of the composite samples is measured by vector network analyzer system.
[0041] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0042] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0043] The present subject matter relates generally to electromagnetic (EM) radiation absorbing composites containing conducting polymer and carbon allotropes. These prepared composites found enormous applications as EM shielding materials, for example, EM-sensitive electronic equipment, stealth vehicles, aircraft, etc., having low radar profiles, protection of electronic components from interference from one another on circuit boards, protection of computer equipment from emitting RF radiation causing interference to navigation systems, medical life support systems, etc. Without being bound by theory, it is believed that in composites of this invention, EM shielding is achieved through absorption of radiation rather than reflection.
[0044] Figure 1 describes the process of fabrication of efficient conducting polymer deposited over different carbon allotropes composites for EMI shielding application. Further, figure 2 illustrates the steps of the figure 1. As shown in the figure 2 at step 202, Amine functionalized multiwalled carbon nanotubes solution is prepared using graphene in organic solvent by Ultrasonicator for 2 hours. In the Ultrasonicator forms the Hybrid Carbon Assemblage using the Amine CNTs and the graphene. The Hybrid Carbon Assemblage is homogenized by sonication in the Ultrasonicator.
[0045] The Sodium Lauryl Sulphate (SLS) doped Polypyrrole is prepared via simple chemical polymerization method by using ferric chloride (FeCl3) as oxidant in the reaction. In the next step 204, SLS doped conducting polymer is added to the amine functionalized multiwalled carbon nanotube suspension and continous stirring of the mixer for six hours to prepare ACNTs@SLS-PPy composite. In the next step 206, the SLS doped conducting polymer is mixed with graphene and Hybrid carbon assemblage via in-situ chemical polymerization method by adding FeCl3. In the step 208, the SLS doped polypyrrole Hybrid carbon assemblage (HCA) is formed. The SLS doped polypyrrole Hybrid carbon assemblage (HCA) is filtered, washed and dried in the vacuum to obtain composite powder for pellets and EMI shielding applications.
[0046] After obtaining the composite powder of the SLS doped polypyrrole Hybrid carbon assemblage (HCA), the composite powder is transformed into the pellets using hydraulic press. The pellets of the composite powder are tested using vector network analyzer (VNA). The measurement of the EMI shielding effectiveness of the composite samples by using a vector network analyzer (VNA E8263B Agilent Technologies) by placing pellet inside a copper sample holder connected between the wave-guide flanges of the network analyzer in the Ku-band (12.4–18.0 GHz) waveguide. Further, the test results are given in the table 1.
[0047] Fig. 3: illustrates XRD patterns of (a) SLS-PPy (b) ACNT@SLS-PPy (c) GR@SLS-PPy (d) HCA@SLS-PPy, in accordance with the present subject matter.
[0048] Fig. 4: illustrates FTIR spectra of (a) SLS-PPy (b) ACNT@SLS-PPy (c) GR@SLS-PPy (d) HCA@SLS-PPy, in accordance with the present subject matter.
[0049] Fig. 5: illustrates FESEM images of (a) SLS-PPy (b) ACNT@SLS-PPy (c) GR@SLS-PPy (d) HCA@SLS-PPy, in accordance with the present subject matter.
[0050] Fig. 6: illustrates Variation of total shielding effectiveness with frequency, in accordance with the present subject matter.
[0051] Fig. 7: Shielding effectiveness due to absorption loss, in accordance with the present subject matter.
[0052] Fig. 8: Shielding effectiveness due to reflection loss, in accordance with the present subject matter.
[0053] The following examples are given to illustrate the process of the present invention and should not be construed to limit the scope of the present invention:
Example 1
Synthesis of Sodium lauryl sulphate doped Poypyrrole coated over three different carbon allotropes substrates:
[0054] The Sodium Lauryl Sulphate doped polypyrrole-amine functionalized carbon nanotube, graphene and hybrid carbon assemblage (AMWCNTs+graphene) composites were prepared via chemical oxidative polymerization of pyrrole dispersed onto carbon nanotubes, graphene and hybrid carbon assemblage. The molar concentration of pyrrole was 0.025M and the resulting composites were designated as (a) SLS-PPy (b) ACNT@SLS-PPy (c) GR@SLS-PPy and (d) HCA@SLS-PPy respectively. A typical preparation protocol for the preparation of composites was described as following. The freshly distilled pyrrole (0.025M) was injected into a suspension of different carbon substrates (0.1g) in 20% methanol solution. The suspension was ultrasonicated for 120 minutes prior to cooling in an ice bath for uniform dispersion. The reaction was then slowly added with an equivalent Sodium Lauryl Sulphate (0.025M) and FeCl3 (0.05M) solution and allowed to proceed at 0–5?C for 24 h. After filtration, the title composite was washed subsequently with methanol and water several times, and the product was dried at overnight at 60?C in vacuum. All as-prepared composites were kept in cool place for followed characterization. Methanol washing is desirable for the removal of oligomeric impurities.
Example 2
Synthesis of Polypyrrole and Sodium dodecyl benzene sulphonate doped Poypyrrole coated over three different carbon substrates:
[0055] The Polypyrrole and polypyrrole-amine functionalized multiwalled carbon nanotube, graphene and hybrid carbon assemblage (AMWCNTs+graphene) composites were prepared via in-situ polymerization of pyrrole dispersed onto carbon nanotubes, graphene and hybrid carbon assemblage. The molar concentration of pyrrole was 0.025M and the resulting composites were designated as PPy-CNT, PPy-GR and PPy-HC respectively. A typical preparation protocol for the preparation of composites was described as following. The freshly distilled pyrrole (0.025M) was injected into a suspension of different carbon substrates (0.1g) in 20% methanol solution. The suspension was ultrasonicated for 40-60 min prior to cooling in an ice bath for uniform dispersion. The reaction was then slowly added with an equivalent FeCl3 (0.49 g in 1 M HCl) solution and allowed to proceed at 0–5?C for 24 h. After filtration, the title composite was washed subsequently with ethanol and water several times, and the product was dried at overnight at 60?C in vacuum. All as-prepared composites were kept in cool place for followed characterization. Sodium dodecyl benzene sulfonate (NaDBS) (0.025M) doped polypyrrole and composites were prepared with similar method as mentioned in above protocol. It is observed that combination of FeCl3 and anionic surfactant NaDBS enhanced the conductivity as well as increased yield of resultant polymer.
Example 3
Synthesis of 5-Sulfoisophthalic acid monolithium salt doped PPy:
[0056] In a typical reaction, 0.05 mol (12.6 g) of LiSiPA and 0.05 mol (3.35 g) of pyrrole was mixed and dissolved in 100 mL distilled water using magnetic stirrer. In another vessel, aqueous solution of ferric chloride was prepared by dissolving 0.1M (16.22 g) of FeCl3 in 200 mL of water. Polymerization was initiated by drop wise addition of FeCl3 solution to aqueous solution of pyrrole/LiSiPA and allowed to stir continuously for 6 h. Temperature of the reaction mixture was kept around 0-6 °C. The polymer thus obtained was separated by filtration and washed repeatedly with distilled water till the pH of the filtrate became neutral. The precipitated polymer was then washed with methanol to remove the oligomers followed by drying under vacuum till constant weight. The dried mass was then crushed to obtain the powder of doped polymer.
Example 4
Synthesis of PPy/MWCNT Composites:
[0057] Synthesis of PPy/MWCNT composites having varying amounts of MWCNTs were prepared by in situ polymerization of pyrrole using the same procedure by keeping amount of pyrrole, LiSiPA, and FeCl3 same as in the preparation of PPy. For the preparation of composites, requisite amount of MWCNTs was dispersed in the aqueous solution of LiSiPA and sonicated for 2 h. After sonication, pyrrole was added to this solution and mixed using magnetic stirrer. The polymerization was then carried out by adding aqueous solution of FeCl3. PPy prepared in the presence of 0, 1, 2, 3, 4, and 5 weight percent of MWCNTs (with respect to monomer weight).
[0058] Embodiments of the present subject matter:
[0059] In the present subject matter, the monomer chosen for study is pyrrole.
[0060] In another embodiment of the present subject matter, the dopant and oxidant chosen for above study was Sodium Lauryl sulphate (SLS) and Ferric Chloride (FeCl3).
[0061] In another embodiment of the present subject matter, the carbon allotropes taken are amine functionalized multiwalled carbon nanotubes, graphene and hybrid carbon assemblage graphene (AMWCNTs+graphene) act as substrates for deposition of conducting polymer.
[0062] In another embodiment of the present subject matter, the solvent of polymerization choose is 1MHCl+20% Methanol Solution.
[0063] In another embodiment of the present subject matter, the temperature of the polymerization condition was kept between 0-5°C.
[0064] In another embodiment of the present subject matter, dopant to monomer and oxidant to monomer ratio was kept 1:1 and 2:1.
[0065] In another embodiment of the present subject matter, the polymerisation reaction time was kept between 6-8 hours.
[0066] In another embodiment of the present subject matter, the prepared composites were washed by deionized water and dried at 50 °C.
[0067] In another embodiment of the present subject matter, measurement of the EMI shielding effectiveness of the composite samples by using a vector network analyzer (VNA E8263B Agilent Technologies) by placing pellet inside a copper sample holder connected between the wave-guide flanges of the network analyzer in the Ku-band (12.4–18.0 GHz) waveguide
[0068] Table 1: EMI shielding data of SLS-PPy and Composites
Table 1
S. No. Sample SLS Pyrrole Amine CNTs Graphene SET
(dB) SEA
(dB) SER
(dB)
1. SLS-PPy 0.025M 0.025M --- --- 30.53 25.05 5.48
2. ACNT@SLS-PPy 0.025M 0.025M 0.1g --- 39.07 30.39 8.68
3. GR@SLS-PPy 0.025M 0.025M --- 0.1g 50.10 41.70 8.30
4. HCA@SLS-PPy 0.025M 0.025M 0.1g 0.1g 80.00 66.00 14.00

[0069] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.