Chemically-Assisted Alignment Nanotubes Within Extensible Structures

Abstract

A method and system for aligning nanotubes within an extensible structure such as a yarn or non-woven sheet. The method includes providing an extensible structure having non-aligned nanotubes, adding a chemical mixture to the extensible structure so as to wet the extensible structure, and stretching the extensible structure so as to substantially align the nanotubes within the extensible structure. The system can include opposing rollers around which an extensible structure may be wrapped, mechanisms to rotate the rollers independently or away from one another as they rotate to stretch the extensible structure, and a reservoir from which a chemical mixture may be dispensed to wet the extensible structure to help in the stretching process.

1 . An extensible nanofibrous structure comprising:
 a plurality of extended length nanotubes in substantial alignment relative to one another; and   a plurality of contact points between adjacent nanotubes, the contact points allowing for a relative increase in conductivity of the extensible structure in comparison to an extensible structure with substantially non-aligned nanotubes.   
     
     
         2 . An extensible nanofibrous structure as set forth in  claim 1 , wherein the increase in conductivity includes increase in electrical conductivity. 
     
     
         3 . An extensible nanofibrous structure as set forth in  claim 1 , wherein the increase in conductivity includes increase in thermal conductivity. 
     
     
         4 . An extensible nanofibrous structure as set forth in  claim 1 , wherein the plurality of contact pointes between adjacent nanotubes allow for a relative increase in tensile strength of the extensible nanofibrous structure in comparison to an extensible nanofibrous structure with substantially non-aligned nanotubes. 
     
     
         5 . An extensible nanofibrous structure as set forth in  claim 1 , wherein the nanotubes are capable of being stretched to allow the extensible to increase to at least about 5% or more of its original length. 
     
     
         6 . An extensible nanofibrous structure as set forth in  claim 1 , wherein the structure is one of a non-woven sheet or a yarn. 
     
     
         7 . An extensible nanofibrous structure as set forth in  claim 1 , wherein the nanotubes include one of carbon nanotubes, boron nanotubes, or a combination thereof. 
     
     
         8 . An extensible nanofibrous structure as set forth in  claim 1 , wherein the nanotubes include one of single wall nanotubes, multiwall nanotubes, or a combination thereof. 
     
     
         9 . An extensible nanofibrous structure as set forth in  claim 1 , further comprising polymers to sterically separate the nanotubes within the extensible nanofibrous structure. 
     
     
         10 . An extensible nanofibrous structure as set forth in  claim 1 , wherein the polymer is one of Poly(vinylpyrrolidone) (PVP), PEO-PBO-PEO triblock polymer (EBE), PEO-PPO-PEO triblock polymers (Pluronic® Series), or a combination thereof. 
     
     
         11 . An extensible nanofibrous structure as set forth in  claim 1 , wherein the nanofibrous structure is a yarn having a resistivity of about 1.6×10 −4  Ω-cm. 
     
     
         12 . An extensible nanofibrous structure as set forth in  claim 1 , wherein the nanofibrous structure is a yarn having a tensile strength of about 800 MPa. 
     
     
         13 . An extensible nanofibrous structure as set forth in  claim 1 , wherein the nanofibrous structure is a non-wove sheet having a resistivity of about 2×10 −4  Ω-cm. 
     
     
         14 . An extensible nanofibrous structure as set forth in  claim 1 , wherein the nanofibrous structure is a non-wove sheet having a a tensile strength of about 1600 MPa. 
     
     
         15 . A system for aligning nanotubes within an extensible structure, the system comprising:
 opposing rollers around which an extensible structure may be wrapped;   a mechanism to rotate the rollers;   means to permit the rollers to move away from one another as they rotate to stretch the extensible structure; and   a reservoir from which a chemical mixture may be dispensed to wet the extensible structure to help in the stretching process.   
     
     
         16 . A system as set forth in  claim 15 , wherein the opposing rollers are designed to permit the extensible structure to be mounted in a loop about the rollers. 
     
     
         17 . A system for aligning nanotubes within an extensible structure, the system comprising:
 a first and second set of pinch rollers adjacent one another, and being designed to permit the extensible structure to be fed between the pinch rollers of each set;   a mechanism to permit each set of pinch rollers to rotate independently of one another so as to stretch the extensible structure being fed; and   a reservoir from which a chemical mixture may be dispensed to wet the extensible structure to help in the stretching process.   
     
     
         18 . A system as set forth in  claim 17 , wherein one set of pinch rollers is designed to move at a slightly faster velocity than other set of pinch rollers. 
     
     
         19 . A system as set forth in  claim 18 , wherein a difference in velocity between the set of pinch rollers ranges from about 1% to about 30%. 
     
     
         20 . An apparatus for forming a nanofibrous structure, the apparatus comprising:
 a housing;   an entrance through which a volume of synthesized nanotubes can flow into the housing; and   a surface situated adjacent the entrance, and designed to rotate in a direction substantially parallel to the flow of nanotubes so as to allow the nanotubes entering the housing to be directed toward the surface, and to be continuously deposited onto the surface to form a nanofibrous structure.   
     
     
         21 . An apparatus as set forth in  claim 20 , wherein the surface is located above the entrance. 
     
     
         22 . An apparatus as set forth in  claim 20 , wherein the surface is located beneath the entrance. 
     
     
         23 . An apparatus as set forth in  claim 20 , wherein the surface includes a ferromagnetic material so as to attract the nanotubes toward the surface.