Figure 1 from U.S. Patent Application 20090304923 shows various types of functionalized multiwall carbon nanotubes manufactured in ten to twenty minutes via microwave radiation by scientists at the New Jersey Institute of Technology.
In U.S. Patent Application 20090304923, New Jersey Institute Of Technology (Newark, NJ) scientists Somenath Mitra (Bridgewater, NJ) and Yuhong Chen (Frederick, MD) reveal a fast method to make improved soluble carbon nanotube (CNT) composites in minutes that are at least partially coated with a metal material.
Mitra and Chen developed improved methods for the synthesis, generation or formation of substantially soluble carbon nanotube composites via microwave reactions. Their methods provide for the rapid, controllable, environmentally-friendly formation of substantially soluble carbon nanotube composites via in-situ microwave-assisted reactions in a process than can be completed in ten minutes to an hour. The carbon nanotube composites are at least partially coated with nanometal particles (e.g., nanoplatinum particles or other metals), and are substantially soluble in water or in organic solvents (e.g., o-dichlorobenzene (ODCB), chloroform, tetrahydrofuran (THF), ethanol, toluene, hexane and DMF).
The microwave technique produces some carbon nanotubes in 10-20 minutes at temperatures of 120 degrees C to 190 degrees C. The complete product process for other MWNT products can be completed in one hour. The process does not work as well for single wall carbon nanotubes (SWNT).
Figure 4 depicts a scanning electron microscope (SEM) image of original MWNTs (mag=400.00 K X, SEM scale bar is 20 nm) made with microwaves in minutes.
Current practice provides that conventional approaches to solubilize CNTs are complex, time-consuming, tedious and involve multiple steps. As such, current practice also provides that attempting to incorporate metal materials (e.g., nanometal particles) on and/or in CNTs is very challenging. In addition, the conventional approach to graft ODA on raw CNTs is via thermal treatment. However, not only is this a very time consuming process, which often requires several days to complete, this method also leads to damage to the CNTs in the process.
Mitra and Chen say CNTs are at least partially coated with a metal, and the effective microwave energy of the process shortens the formation process to about one hour, thereby dramatically improving the performance of the whole formation process compared to conventional thermal methods in which just the solubilizing process for CNTs can take several days to complete.
Furthermore, in exemplary embodiments, the selected reaction solvent (e.g., ethanol) may help to facilitate the nanometal particle coating portion of the process in just several minutes. Additionally, the advantageous, faster microwave systems and methods of the disclosure do not alter and/or damage the CNTs during processing, thereby providing a significant commercial and manufacturing advantage as a result. Microwave processing can also reduce the need for solvents, thus it is eco-friendly.
Functionalization allows the chemical structure of the nanotubes to be modified, and other functional groups, polymers, ceramics, biological molecules such as enzymes and other appropriate chemical moieties can be attached. For example, treating with acid generates --COOH groups to which other functionalities can be attached by a variety of chemical reactions. Some functionalization reactions may be, for example, carboxylation, sulfonation, esterification, thiolation, carbine addition, nitration, nucleophylic cyclopropanation, bromination, fluorination, diels alder reaction, amidation, cycloaddition, polymerization, adsorption of polymers, addition of biological molecules and enzymes, etc.
The functionalization may be covalent bonding to the nanotube, or noncovalent adsorption or wrapping. By synthesizing the appropriate functionality, the nanotubes may be rendered soluble in aqueous, organic, polar, nonpolar, hydrogen bonding, ionic liquids, and other solvents so that they can be processed easily.
In general, say the inventors, during microwave-assisted reactions, the smaller diameter and higher curvature of SWNTs generates more stress in the SWNTs than in the MWNTs. However, it is to be noted that the additional layers in MWNTs may result in more adsorption of microwave radiation by the MWNTs in the disclosed systems and methods. As such, the MWNTs may be easier to handle compared to the SWNTs under the microwave methods Additionally, the chemical activation parameters may be modified due to further polarization of the dipoles under microwave radiation.
Mitra and Chen developed improved methods for the synthesis, generation or formation of substantially soluble carbon nanotube composites via microwave reactions. Their methods provide for the rapid, controllable, environmentally-friendly formation of substantially soluble carbon nanotube composites via in-situ microwave-assisted reactions in a process than can be completed in ten minutes to an hour. The carbon nanotube composites are at least partially coated with nanometal particles (e.g., nanoplatinum particles or other metals), and are substantially soluble in water or in organic solvents (e.g., o-dichlorobenzene (ODCB), chloroform, tetrahydrofuran (THF), ethanol, toluene, hexane and DMF).
The microwave technique produces some carbon nanotubes in 10-20 minutes at temperatures of 120 degrees C to 190 degrees C. The complete product process for other MWNT products can be completed in one hour. The process does not work as well for single wall carbon nanotubes (SWNT).
Figure 4 depicts a scanning electron microscope (SEM) image of original MWNTs (mag=400.00 K X, SEM scale bar is 20 nm) made with microwaves in minutes.
Current practice provides that conventional approaches to solubilize CNTs are complex, time-consuming, tedious and involve multiple steps. As such, current practice also provides that attempting to incorporate metal materials (e.g., nanometal particles) on and/or in CNTs is very challenging. In addition, the conventional approach to graft ODA on raw CNTs is via thermal treatment. However, not only is this a very time consuming process, which often requires several days to complete, this method also leads to damage to the CNTs in the process.
Mitra and Chen say CNTs are at least partially coated with a metal, and the effective microwave energy of the process shortens the formation process to about one hour, thereby dramatically improving the performance of the whole formation process compared to conventional thermal methods in which just the solubilizing process for CNTs can take several days to complete.
Furthermore, in exemplary embodiments, the selected reaction solvent (e.g., ethanol) may help to facilitate the nanometal particle coating portion of the process in just several minutes. Additionally, the advantageous, faster microwave systems and methods of the disclosure do not alter and/or damage the CNTs during processing, thereby providing a significant commercial and manufacturing advantage as a result. Microwave processing can also reduce the need for solvents, thus it is eco-friendly.
Functionalization allows the chemical structure of the nanotubes to be modified, and other functional groups, polymers, ceramics, biological molecules such as enzymes and other appropriate chemical moieties can be attached. For example, treating with acid generates --COOH groups to which other functionalities can be attached by a variety of chemical reactions. Some functionalization reactions may be, for example, carboxylation, sulfonation, esterification, thiolation, carbine addition, nitration, nucleophylic cyclopropanation, bromination, fluorination, diels alder reaction, amidation, cycloaddition, polymerization, adsorption of polymers, addition of biological molecules and enzymes, etc.
The functionalization may be covalent bonding to the nanotube, or noncovalent adsorption or wrapping. By synthesizing the appropriate functionality, the nanotubes may be rendered soluble in aqueous, organic, polar, nonpolar, hydrogen bonding, ionic liquids, and other solvents so that they can be processed easily.
In general, say the inventors, during microwave-assisted reactions, the smaller diameter and higher curvature of SWNTs generates more stress in the SWNTs than in the MWNTs. However, it is to be noted that the additional layers in MWNTs may result in more adsorption of microwave radiation by the MWNTs in the disclosed systems and methods. As such, the MWNTs may be easier to handle compared to the SWNTs under the microwave methods Additionally, the chemical activation parameters may be modified due to further polarization of the dipoles under microwave radiation.
