Method of preparation of a MWCNT/polymer composite having electromagnetic interference shielding effectiveness

• US 8,367,161 B2
• Filed: 04/26/2011
• Issued: 02/05/2013
• Est. Priority Date: 10/19/2007
• Status: Active Grant

• Current Assignee: National Tsing Hua University
• Original Assignee: National Tsing Hua University
• Inventors: Ma, Chen-Chi Martin, Yuen, Siu-Ming, Chuang, Chia-Yi, Yu, Kuo-Chi, Wu, Sheng Yen
• Primary Examiner(s): CAMERON, ERMA C
• Application Number:
  US13/094,201
• Publication Number:
  US 20110200740A1
• Time in Patent Office: 651 Days
• Field of Search: None
• US Class Current: 427/372.2
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C08J 2300/12 Polymers characterised by physical features, e.g. anisotropy, viscosity or electrical conductivity
• CPC Class Codes: C08J 2333/12 Homopolymers or copolymers of methyl methacrylate
• CPC Class Codes: C08J 2367/02 Polyesters derived from dicarboxylic acids and dihydroxy compounds; C08J2367/06 takes precedence
• CPC Class Codes: C08J 2433/00 Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers
• CPC Class Codes: C08J 5/005 Reinforced macromolecular compounds with nanosized materials, e.g. nanoparticles, nanofibres, nanotubes, nanowires, nanorods or nanolayered materials
• CPC Class Codes: C08J 7/0427 with only one layer of a composition containing a polymer binder with more layers C08J7/042
• CPC Class Codes: C08J 7/043 Improving the adhesiveness of the coatings per se, e.g. forming primers adhesives in the form of films or foils characterised by the primer layers between the polymer carriers and the adhesives C09J7/50
• CPC Class Codes: H05K 9/0092 comprising electro-conductive pigments, e.g. paint, ink, tampon printing

Abstract

A method of preparing carbon nanotube/polymer composite having electromagnetic interference (EMI) shielding effectiveness is disclosed, which includes: dispersing multi-walled carbon nanotubes (MWCNT) in an organic solvent such as N,N-Dimethylacetamide (DMAc); dissolving monomers such as methyl methacrylate (MMA) and an initiator such as 2,2-azobisisobutyronitrile (AIBN) in the MWCNT dispersion; and polymerizing the monomers in the resulting mixture at an elevated temperature such as 120° C. to form a MWCNT/PMMA composite. The composite is coated onto a PET film, and the coated PET film alone or a stack of multiple coated PET films can be applied as an EMI shielding material.

Claims

1. A method of preparing carbon nanotube/polymer composite having electromagnetic interference (EMI) shielding effectiveness, which comprises the following steps:

a) preparing a polymer solution containing 0.5-10 wt % of carbon nanotubes dispersed therein, based on the weight of the polymer;

b) coating the polymer solution containing carbon nanotubes dispersed therein on a substrate and drying the resulting layer coated on the substrate; and

c) stacking a plurality of the substrates prepared from step b), each of which has the dried layer;

wherein said preparing in step a) comprises dissolving a polymer in an organic solvent and dispersing carbon nanotubes in the resulting polymer solution to form said polymer solution containing carbon nanotubes dispersed therein, and

wherein said substrate in step b) is a film of poly(ethylene terephthalate), polyimide, polyethylene, polypropylene, or poly(vinyl chloride).

2. The method as claimed in claim 1, wherein step c) further comprises applying an adhesive on the substrates prior to said stacking so that the stacked substrates are bonded.

3. The method as claimed in claim 1, wherein the dried layer on the substrate prepared in step b) has a thickness of 0.05 mm to 1.0 mm.

4. The method as claimed in claim 2, wherein the dried layer on the substrate prepared in step b) has a thickness of 0.05 mm to 1.0 mm, and 2 to 100 sheets of the substrates are stacked in step c).

5. The method as claimed in claim 1, wherein the carbon nanotubes are multi-walled carbon nanotubes.

6. The method as claimed in claim 1, wherein said polymer is selected from the group consisting of poly(acrylic acid), poly(methacrylic acid), poly(methyl acrylate), poly(methyl methacrylate), soluble polyimide, soluble poly(amide imide), polyamide, polystyrene, soluble polyurethane, unsaturated polyester, poly(ether sulfone), soluble poly(ether imide), poly(vinyl ester), thermoplastic polyurethane, silicone, and epoxy resin.

7. The method as claimed in claim 6, wherein said polymer is poly(methyl methacrylate).

8. The method as claimed in claim 7, wherein said poly(methyl methacrylate) is prepared by polymerizing methyl methacrylate in a solvent of N,N-Dimethylacetamide and in the presence of an initiator of 2,2-azobisisobutyronitrile at 120°

C.

9. The method as claimed in claim 1, wherein said substrate in step b) is a poly(ethylene terephthalate) film.

10. The method as claimed in claim 1, wherein said substrate in step b) is a polypropylene film.

11. The method as claimed in claim 1, wherein said substrate in step b) is a poly(vinyl chloride) film.

12. A method of using a carbon nanotube/polymer composite to provide electromagnetic interference (EMI) shielding comprising preparing a carbon nanotube/polymer composite by using the method as defined in claim 1;

and enclosing an electronic device in the carbon nanotube/polymer composite.