Low thermal conductivity carbon-containing materials and methods of producing the same

Abstract

The presently disclosed subject matter relates generally to low thermal conductivity carbon materials and methods of producing the same. In some embodiments, the carbon materials are doped with low thermally conductive nanoparticles. In some embodiments, carbon fibers are prepared by electrospinning a mixture of polymers; and/or incorporating a low thermal conductivity additive, such as nanoparticles.

1 . A method of preparing a multi-scale porous carbon-containing material, having a thermal conductivity of less than about 5 W/m K, the method comprising
 a. electrospinning a spin dope comprising a first polymer that is a carbon precursor; and further comprising
 i. a second polymer having a decomposition temperature lower than about 600° C.; and/or 
 ii. nanoparticles having a boiling point above about 1400° C. and a thermal conductivity of less than about 10 W/m K;
 wherein said electrospinning yields a polymer nanofiber; 
 
   b. stabilizing said polymer nanofiber; and   c. carbonizing said stabilized nanofiber at no more than about 1000° C.   
     
     
         2 . The method of  claim 1 , wherein the multi-scale porous carbon-containing material comprises an electrospun carbon nanofiber and has:
 a. pores having an average pore width between about 1 μm and about 10 μm;   b. pores having an average pore width between about 100 nm and about 1000 nm; and/or   c. pores having an average pore width between about 1 nm and about 100 nm.   
     
     
         3 . The method of  claim 1 , wherein said multi-scale porous carbon-containing material has a thermal conductivity of less than about 3 W/m K. 
     
     
         4 . The method of  claim 1 , wherein said first polymer is polyacrylonitrile. 
     
     
         5 . (canceled) 
     
     
         6 . (canceled) 
     
     
         7 . The method of  claim 1 , wherein said second polymer is poly(methyl methacrylate). 
     
     
         8 . The method of  claim 1 , wherein said first polymer is polyacrylonitrile, said second polymer is poly(methyl methacrylate) and the ratio of polyacrylonitrile to poly(methyl methacrylate) is between about 70:30 and about 50:50. 
     
     
         9 . The method of  claim 1 , wherein said nanoparticles comprise silicon dioxide. 
     
     
         10 . The method of  claim 4 , wherein said nanoparticles in the spin dope comprise at least about 2.5 wt % relative to the weight of polyacrylonitrile. 
     
     
         11 . (canceled) 
     
     
         12 . The method of  claim 1 , comprising:
 a. electrospinning a spin dope comprising polyacrylonitrile and
 i. a second polymer having a decomposition temperature lower than about 600° C.; and 
 ii. nanoparticles comprising silicon dioxide or calcium silicate;
 wherein said electrospinning yields a polymer nanofiber; 
 
   b. stabilizing said polymer nanofiber; and   c. carbonizing said stabilized nanofiber at no more than about 1000° C.   
     
     
         13 . The method of  claim 1 , comprising electrospinning a spin dope comprising polyacrylonitrile, poly(methyl methacrylate), and nanoparticles comprising silicon dioxide. 
     
     
         14 . The method of  claim 1 , wherein
 said stabilizing comprises heating said polymer nanofiber to between about 220° C. and about 300° C. and holding said temperature for sufficient time to yield a stabilized intermediate; and   wherein said carbonizing comprises heating said stabilized intermediate to no more than about 900° C. and holding at said carbonization temperature for at least about 30 minutes.   
     
     
         15 . (canceled) 
     
     
         16 . A nanofibrous carbon product comprising nanoparticles
 wherein said nanoparticles have a boiling point above about 1400° C. and a thermal conductivity of less than about 10 W/m K,   wherein said nanofibrous carbon product has a thermal conductivity of no more than about 5 W/m K.   
     
     
         17 . The nanofibrous carbon product of  claim 16 , wherein said product comprises
 a. pores having an average pore width between about 1 μm and about 10 μm;   b. pores having an average pore width between about 100 nm and about 1000 nm; and/or   c. pores having an average pore width between about 1 nm and about 100 nm.   
     
     
         18 . The nanofibrous carbon product of  claim 16 , wherein said nanofibrous carbon product comprises electrospun carbon nanofibers, optionally wherein said nanofibers comprise a carbon nanofiber yarn. 
     
     
         19 . The nanofibrous carbon product of  claim 16 , wherein said nanoparticles comprise silicon dioxide. 
     
     
         20 . (canceled) 
     
     
         21 . A thermal insulating material comprising the nanofibrous carbon product of  claim 16 . 
     
     
         22 . A thermal insulating material comprising a multi-scale porous carbon-containing material prepared according to the method of  claim 1 , wherein said carbon-containing material has a thermal conductivity of no more than about 4 W/m K. 
     
     
         23 . A multi-scale porous carbon-containing structure comprising carbon nanofibers having an average nanofiber diameter of between about 300 nm and about 700 nm, the structure having
 a. a thermal conductivity below about 4 W/m K;   b. a specific surface area of at least about 30 m 2 /g as measured by BET isotherm; and/or   c. a total pore volume of at least about 0.13 cm 3 /g as measured by N 2  gas sorption.   
     
     
         24 . The structure of  claim 23 , wherein the structure has a thermal conductivity below about 2 W/m K and an average nanofiber diameter of between about 400 nm and about 600 nm. 
     
     
         25 . A thermal insulating material comprising the multi-scale porous structure of  claim 23 .