Methods for preparing carbon nanotube/polymer composites using free radical precursors
In some embodiments, the present invention is directed to methods of fully integrating CNTs and the surrounding polymer matrix in CNT/polymer composites. In some such embodiments, such integration comprises interfacial covalent bonding between the CNTs and the polymer matrix. In some such embodiments, such interfacial covalent bonding is provided by a free radical reaction initiated during processing. In some such embodiments, such free radical initiation can be provided by benzoyl peroxide. In some or other embodiments, the present invention is directed to CNT/polymer composite systems, wherein the CNTs within such systems are covalently integrated with the polymer. In some or other embodiments, the present invention is directed to articles of manufacture made from such CNT/polymer composite systems.
1. A method comprising the steps of:
a) dispersing CNTs, a thermoplastic polymer, and a free radical precursor species in a solvent;
b) removing the solvent to form polymer-overcoated CNTs comprising the free radical precursor species; and
c) compounding the polymer-overcoated CNTs comprising the free radical precursor species;
wherein the compounding step comprises forming a fully-integrated CNT/polymer composite;
wherein the fully-integrated CNT/polymer composite has interfacial covalent bonding between the CNTs and the polymer; and
wherein the interfacial covalent bonding comprises at least one carbon-carbon covalent bond between the CNTs and the thermoplastic polymer.
2. The method of claim 1 , further comprising a step of processing the fully-integrated CNT/polymer composite in an extruder by shear forces.
3. The method of claim 2 , wherein the CNTs become substantially aligned during the processing step.
4. The method of claim 1 , wherein the CNTs are selected from the group consisting of single-wall carbon nanotubes, multi-wall carbon nanotubes, double-wall carbon nanotubes, and combinations thereof.
5. The method of claim 1 , wherein the dispersing step comprises use of a surfactant.
6. The method of claim 1 , wherein the solvent is selected from the group consisting of CHCl 3 , THF, toluene, o-dichlorobenzene, and combinations thereof.
7. The method of claim 1 , wherein the CNTs comprise single-wall carbon nanotubes.
8. The method of claim 1 , wherein the thermoplastic polymer comprises polypropylene.
9. The method of claim 1 , wherein the free radical precursor species is a peroxide.
10. The method of claim 1 , wherein the free radical precursor species is benzoyl peroxide.
11. The method of claim 1 , wherein the free radical precursor species decomposes to a free radical species during the compounding step; and
wherein the free radical species initiates formation of the interfacial covalent bonding between the CNTs and the thermoplastic polymer.
12. A method comprising the steps of:
a) dispersing SWNTs, a thermoplastic polymer, and an organic peroxide species in a solvent;
b) removing the solvent to form polymer-overcoated SWNTs comprising the organic peroxide species;
c) compounding the polymer-overcoated SWNTs comprising the organic peroxide species;
wherein the compounding step comprises forming a fully-integrated SWNT/polymer composite;
wherein the fully-integrated SWNT/polymer composite has interfacial covalent bonding between the SWNTs and the polymer; and
wherein the interfacial covalent bonding comprises at least one carbon-carbon covalent bond between the SWNTs and the thermoplastic polymer; and
d) processing the fully-integrated SWNT/polymer composite in an extruder by shear forces.
13. The method of claim 12 , wherein the SWNTs become substantially aligned in the processing step.
14. The method of claim 12 , wherein the dispersing step comprises use of a surfactant.
15. The method of claim 12 , wherein the solvent is selected from the group consisting of CHCl 3 , THF, toluene, o-dichlorobenzene, and combinations thereof.
16. The method of claim 12 , wherein the organic peroxide species is benzoyl peroxide.
17. The method of claim 12 , wherein the thermoplastic polymer comprises polypropylene.
18. The method of claim 12 , wherein the organic peroxide species decomposes to a free radical species during the compounding step; and
wherein the free radical species initiates formation of the interfacial covalent bonding between the SWNTs and the thermoplastic polymer.
19. An article comprising the fully-integrated CNT/polymer composite prepared by the method of claim 3 .
20. The article of claim 19 , wherein the CNTs comprise SWNTs.