Compositions comprising carbon nanotubes and articles formed therefrom

Abstract

Improved compositions comprise a polymer and carbon fibers, such as nanotubes. In some embodiments, the carbon fibers, e.g., nanotubes, can be mechanically blended or incorporated into the polymer, while in some embodiments carbon nanotubes also may be covalently bonded to the polymer to form corresponding covalent materials. In particular, the polymer can be covalently bonded to the side walls of the carbon nanotubes to form a composite with particularly desirable mechanical properties. Specifically, the bonding of the polymer to the nanotube sidewall can provide desirable mechanical properties of the composite due to the orientation relative to other types of association between the nanotubes and the polymer. The processing of the nanotubes can be facilitated by the dispersion of the nanotubes in an aqueous solution comprising a hydrophylic polymer, such as ethyl vinyl acetate. A dispersion of nanotubes can be combined with a polymer in an extrusion process to blend the materials under high shear, such as in an extruder. In general, various articles can be formed that take advantage of the properties of the composite materials incorporating a polymer and carbon fibers, such as carbon nanotubes.

1 . A composition comprising a polymer covalently bonded to the side walls of carbon nanotubes.  
     
     
         2 . The composition of  claim 1  wherein the nanotubes comprise single wall carbon nanotubes, multiple wall carbon nanotubes, or a combination thereof.  
     
     
         3 . The composition of  claim 1  wherein the carbon nanotubes are present in a concentration of less than about 50 percent by weight.  
     
     
         4 . The composition of  claim 1  wherein the carbon nanotubes are present in a concentration from about 0.1 percent by weight to about 40 percent by weight.  
     
     
         5 . The composition of  claim 1  wherein the polymer is selected from the group consisting of PEI, Polyimide, Poly ether sulfone (PES), Poly phenyl sulfone (PPS), Per fluoro alkoxy (PFA), Fluorinated ethylene propylene (FEP), Ethylene tri fluoro ethylene (ETFE) Poly sulfone, Polystyrene, Poly ether Ketone (PEK), Poly ether ketone ketone (PEKK), polybutylene terephthalate (PBT), polyolefins (PO), polyethylene terephthalate (PET), styrene block co-polymers, styrene-butadiene rubber, nylon in the form of polyether block polyamide (PEBA), polyetheretherketone (PEEK), poly(vinylidenefluroide), poly(tetraflurorethylene) (PTFE), polyethylene, polypropylene, poly(vinylchloride) (PVC), ethyl vinyl acetate and blends and copolymers thereof.  
     
     
         6 . The composition of  claim 1  wherein the carbon nanotubes have functional groups attached to the side walls that bridge between the walls of the nanotubes and the polymer.  
     
     
         7 . The composition of  claim 6  wherein the polymer is a multifunctional polymer having two or more functional groups that are covalently bonded with carbon nanotubes.  
     
     
         8 . The composition of  claim 7  wherein the polymer is covalently bonded to the nanotubes to form polymer-nanotube structures that can self order.  
     
     
         9 . The composition of  claim 7  wherein the polymer is covalently bonded to the nanotubes such that polymer chains are crosslinked by the nanotubes.  
     
     
         10 . An article comprising the composition of  claim 1 .  
     
     
         11 . The article of  claim 10  wherein the article comprises a wafer carrier suitable for transporting semi-conductor wafers.  
     
     
         12 . The article of  claim 10  wherein the article comprises a bipolar plate.  
     
     
         13 . The article of  claim 10  wherein the article comprises an electrode.  
     
     
         14 . A liquid dispersion comprising ethyl vinyl acetate and carbon fibers.  
     
     
         15 . The liquid dispersion of  claim 14  wherein the carbon fibers comprise single wall carbon nanotubes, multiple wall carbon nanotubes or a combination thereof.  
     
     
         16 . The liquid dispersion of  claim 14  wherein the carbon fibers are present in a concentration of less than about 50 percent by weight.  
     
     
         17 . The liquid dispersion of  claim 14  wherein the carbon fibers are presenting a concentration from about 0.1 percent by weight to about 40 percent by weight.  
     
     
         18 . The liquid dispersion of  claim 14  wherein the carbon fibers comprise functional groups located on the ends of the nanotubes, along the side walls of the nanotubes, or both.  
     
     
         19 . The liquid dispersion of  claim 18  wherein the functional groups comprise fluorine.  
     
     
         20 . The liquid dispersion of  claim 14  wherein the dispersion comprises an aqueous dispersion.  
     
     
         21 . The liquid dispersion of  claim 14  wherein the EVA has a melt index from about 2 g/10 mn to about 800 g/10 mn as determined by ASTM D1238 procedure with a temperature of 190° C. and a load of 2.16 Kg.  
     
     
         22 . The liquid dispersion of  claim 14  wherein the EVA has a density from about 0.92 g/cm 3  to about 0.95 g/cm 3 .  
     
     
         23 . The liquid dispersion of  claim 14  wherein the EVA has a VA content from about 20 percent to about 30 percent.  
     
     
         24 . The liquid dispersion of  claim 14  wherein the weight ratio of EVA to nanotubes is from about 0.005 to about 1.  
     
     
         25 . A liquid dispersion comprising poly(vinyl alcohol) and carbon fibers.  
     
     
         26 . An article comprising a polymer and fluorinated carbon nanotubes.  
     
     
         27 . The article of  claim 25  wherein the carbon nanotubes comprise single wall carbon nanotubes, multiple wall carbon nanotubes or a combination thereof.  
     
     
         28 . The article of  claim 26  wherein the fluorinated carbon nanotubes are covalently bonded to the polymer.  
     
     
         29 . The article of  claim 26  wherein the fluorinated carbon nanotubes a mixed throughout the polymer.  
     
     
         30 . The article of  claim 26  wherein the polymer and fluorinated carbon nanotubes are coated onto the surface of the article.  
     
     
         31 . The article of  claim 26  wherein the fluorinated carbon nanotubes are present in a concentration of less than about 50 percent by weight.  
     
     
         32 . The article of  claim 26  wherein the fluorinated carbon nanotubes are present in a concentration from about 0.1 percent by weight to about 40 percent by weight.  
     
     
         33 . The article of  claim 26  wherein the polymer is selected from the group consisting of polybutylene terephthalate (PBT), polyolefins (PO), polyethylene terephthalate (PET), styrene block co-polymers, styrene-butadiene rubber, nylon in the form of polyether block polyamide (PEBA), polyetheretherketone (PEEK), poly(vinylidenefluroide), poly(tetraflurorethylene) (PTFE), polyethylene, polypropylene, poly(vinylchloride) (PVC), ethyl vinyl acetate and blends and copolymers thereof.  
     
     
         34 . The article of  claim 26  wherein the article comprises a wafer carrier having structural elements suitable for transporting a plurality of semi-conductor wafers.  
     
     
         35 . The article of  claim 26  wherein the article comprises a bipolar plate suitable for use in electrochemical cells.  
     
     
         36 . A method of forming a composite, the method comprising injecting a liquid dispersion of carbon fibers within an extruder having a polymer within the extruder and applying shear to blend the carbon fibers and the polymer.  
     
     
         37 . The method of  claim 36  wherein the liquid dispersion of carbon fibers comprises an aqueous dispersion of carbon fibers and ethyl vinyl acetate.  
     
     
         38 . The method of  claim 37  wherein the carbon fibers comprise single wall carbon nanotubes, multiple wall carbon nanotubes, or a combination thereof.  
     
     
         39 . The method of  claim 37  wherein the carbon fibers are present at a concentration of less than about 50 percent by weight.  
     
     
         40 . The method of  claim 37  wherein the carbon fibers are present at a concentration from about 0.1 percent by weight to about 40 percent by weight.  
     
     
         41 . The method of  claim 36  wherein the carbon fibers comprise functional groups that can covalently bond with the polymer, wherein covalent bonding between the carbon fibers and the polymer occurs in the extruder.  
     
     
         42 . The method of  claim 36  wherein the composite is fed from the extruder to a shaping apparatus where the composite is formed into an article having a desired shape and size.  
     
     
         43 . The method of  claim 42  wherein the shaping apparatus is selected form the group consisting of rollers, injection molds, compression molds, and combinations thereof.  
     
     
         44 . The method of  claim 36  wherein the composite is feed from the extruder and coated onto an article to provide a layer of the composite on a surface of the article.  
     
     
         45 . The method of  claim 36  wherein the extruder comprises a twin-screw extruder.  
     
     
         46 . A wafer carrier comprising a slot for the support of a wafer, wherein the slot comprises wafer contact points having a surface with a composite of polymer associated with carbon nanotubes.  
     
     
         47 . The wafer carrier of  claim 46  wherein carbon nanotubes are mixed throughout the polymer.  
     
     
         48 . The wafer carrier of  claim 46  wherein the carbon nanotubes are covalently bonded to the polymer.  
     
     
         49 . The wafer carrier of  claim 46  wherein the carbon nanotubes comprise single wall carbon nanotubes.  
     
     
         50 . The wafer carrier of  claim 46  wherein the carbon nanotubes are present in a concentration of less than about 1 percent by weight.  
     
     
         51 . The wafer carrier of  claim 46  wherein the carbon nanotubes are present in a concentration less than about 0.5 percent by weight.  
     
     
         52 . The wafer carrier of  claim 46  wherein the transparency of the polymer not affected by the carbon nanotubes.  
     
     
         53 . The wafer carrier of  claim 46  wherein the composite reduces electrostatic discharge relative to carriers made of plastic.  
     
     
         54 . The wafer carrier of  claim 46  wherein the polymer is selected from the group consisting of polybutylene terephthalate (PBT), polyolefins (PO), polyethylene terephthalate (PET), styrene block co-polymers, styrene-butadiene rubber, nylon in the form of polyether block polyamide (PEBA), polyetheretherketone (PEEK), poly(vinylidenefluroide), poly(tetraflurorethylene) (PTFE), polyethylene, polypropylene, poly(vinylchloride) (PVC), ethyl vinyl acetate and blends and copolymers thereof.  
     
     
         55 . A fuel cell comprising a bipolar plate, the bipolar plate comprising a composite of polymer associated with carbon nanotubes.  
     
     
         56 . The bipolar plate of  claim 55  wherein the carbon nanotubes are mixed within the polymer.  
     
     
         57 . The bipolar plate of  claim 55  wherein the carbon nanotubes are covalently bonded to the polymer.  
     
     
         58 . The bipolar plate of  claim 55  wherein the carbon nanotubes comprise single wall carbon nanotubes, multiple wall carbon nanotubes, or a combination thereof.  
     
     
         59 . The bipolar plate of  claim 55  wherein the carbon nanotubes are present in a concentration from about 1 percent by weight to about 50 percent by weight.  
     
     
         60 . The bipolar plate of  claim 55  wherein the polymer is selected from the group consisting of polybutylene terephthalate (PBT), polyolefins (PO), polyethylene terephthalate (PET), styrene block co-polymers, styrene-butadiene rubber, nylon in the form of polyether block polyamide (PEBA), polyetheretherketone (PEEK), poly(vinylidenefluroide), poly(tetraflurorethylene) (PTFE), polyethylene, polypropylene, poly(vinylchloride) (PVC), ethyl vinyl acetate and blends and copolymers thereof.  
     
     
         61 . The bipolar plate of  claim 55  further comprising a first side and a second side wherein the first side comprises reactant flow channels formed into the surface of the plate.  
     
     
         62 . The bipolar plate of  claim 61  wherein the second side comprises reactant flow channels formed into the surface of the plate.