Hybrid felts of electrospun nanofibers

Abstract

The present invention relates generally to compositions for use in biological and chemical separations, as well as other applications. More specifically, the present invention relates to hybrid felts fabricated from electrospun nanofibers with high permeance and high capacity. Such hybrid felts utilize derivatized cellulose, and at least one non-cellulose-based polymer that may be removed from the felt by subjecting it to moderately elevated temperatures and/or solvents capable of dissolving the non-cellulose-based polymer to leave behind a porous nanofiber felt having more uniform pore sizes and other enhanced properties when compared to single component nanofiber felts.

What is claimed is: 
     
       1. An electrospun hybrid nanofiber felt comprising:
 a composite nanofiber and a single component nanofiber, wherein the composite nanofiber comprises a mixture of a derivatized cellulose and a first non-cellulose-based polymer, and wherein the single component nanofiber comprises a second non-cellulose-based polymer, wherein the first and second non-cellulose-based polymers are differentially removable from the nanofiber felt, wherein one or more of the nanofibers are surface functionalized. 
 
     
     
       2. The nanofiber felt according to  claim 1 , wherein the composite nanofiber is surface functionalized. 
     
     
       3. The nanofiber felt according to  claim 1 , wherein the single component nanofiber is surface functionalized. 
     
     
       4. The nanofiber felt according to  claim 1 , wherein the surface functionalization comprises the addition of an ion-exchange group, a hydrophobic group, and/or an affinity ligand. 
     
     
       5. The nanofiber felt according to  claim 4 , wherein the surface functionalization is an ion-exchange group, and wherein the ion-exchange group is a weak anion exchange group, or a weak cation exchange group. 
     
     
       6. The nanofiber felt according to  claim 4 , wherein the surface functionalization is a hydrophobic group, and wherein the hydrophobic group is a phenyl group or a butyl group. 
     
     
       7. The nanofiber felt according to  claim 1 , wherein the composite nanofiber contains less than 49% by mass of the first non-cellulose based polymer. 
     
     
       8. The nanofiber felt according to  claim 7 , wherein the first and second non-cellulose-based polymers are selected from the group consisting of a thermoplastic homopolymer, a thermoplastic copolymer, an elastomeric polymer, a polyimide polymer, an aromatic polyamide polymer, a liquid crystalline polymer, a textile polymer, an electrically conductive polymer, a biocompatible polymer and copolymers thereof. 
     
     
       9. The nanofiber felt according to  claim 7 , wherein the first and second non-cellulose-based polymers are selected from the group consisting of a vinyl polymer, a polyether, an acrylic polymer, a polyester, a polycarbonate, a polyurethane, an ethylene-propylene-diene-elastomer, a polyimide, a polysaccharide, a polyamide, a polylactide, a poly(p-phenylene terephthalamide), a polyaramid, a polyethylene terephthalate, a polyacrylonitrile, a polyaniline, a polycaprolactone, a polyglycolide, a polyethylene oxide, a poly(vinylpyrrolidone), a poly(vinyl acetate), a poly(vinyl alcohol), a polystyrene, a poly(methyl methacrylate), a protein, and copolymers thereof. 
     
     
       10. An electrospun hybrid nanofiber felt comprising:
 a composite nanofiber and a single component nanofiber; wherein the composite nanofiber comprises a mixture of a derivatized cellulose and a first non-cellulose-based polymer, and wherein the composite nanofiber contains less than 49% by mass of the first non-cellulose based polymer; and wherein the single component nanofiber comprises a second non-cellulose-based polymer, wherein the first and second non-cellulose-based polymers are differentially removable from the nanofiber felt, wherein one or more of the nanofibers are surface functionalized. 
 
     
     
       11. The nanofiber felt according to  claim 10 , wherein the composite nanofiber is surface functionalized. 
     
     
       12. The nanofiber felt according to  claim 10 , wherein the single component nanofiber is surface functionalized. 
     
     
       13. A separation method comprising:
 a) flowing a fluid through the nanofiber felt of  claim 10 ; and 
 b) separating molecules from the fluid. 
 
     
     
       14. The method of  claim 13 , wherein the separating step is a size-based separation. 
     
     
       15. The method of  claim 13 , wherein the separating step is an adsorption-based separation. 
     
     
       16. The method of  claim 15 , wherein the adsorption-based separation is an ionic separation, hydrophobic separation, or affinity separation. 
     
     
       17. The method according to  claim 13 , wherein the molecules comprise a one or more of a metal ion, a protein, a nucleic acid, or a virus. 
     
     
       18. The method according to  claim 17 , further comprising a step:
 c) recovering the molecules from the nanofiber felt. 
 
     
     
       19. The method according to  claim 13 , further comprising a step:
 c) flowing the fluid through a second nanofiber felt of  claim 10 ; wherein the separation process of step a) and separation process of step c) are different. 
 
     
     
       20. The method of  claim 13 , further comprising a step:
 c) recovering the fluid. 
 
     
     
       21. A membrane prepared by the process comprising:
 providing an electrospun nanofiber felt comprising a composite nanofiber and a single component nanofiber,
 wherein the composite nanofiber comprises a mixture of a derivatized cellulose and a first non-cellulose-based polymer, and 
 wherein the single component nanofiber comprises a second non-cellulose-based polymer, 
 wherein the first and second non-cellulose-based polymers are differentially removable from the nanofiber felt; 
   removing the first or second non-cellulose-based polymer from the nanofiber felt to form the membrane, which has a plurality of pores.    
     
     
       22. The membrane according to claim 21, wherein one or more of the nanofibers are surface functionalized.  
     
     
       23. The membrane according to claim 22, wherein the composite nanofiber is surface functionalized.  
     
     
       24. The membrane according to claim 22, wherein the single component nanofiber is surface functionalized.  
     
     
       25. The membrane according to claim 22, wherein the surface functionalization comprises the addition of an ion-exchange group, a hydrophobic group, and/or an affinity ligand.  
     
     
       26. The membrane according to claim 25, wherein the surface functionalization is an ion-exchange group, and wherein the ion exchange group comprises a strong acid, a weak acid, or a base.  
     
     
       27. The membrane according to claim 25, wherein the surface functionalization is a hydrophobic group, and wherein the hydrophobic group is a phenyl group or a butyl group.  
     
     
       28. The membrane according to claim 21, wherein the composite nanofiber contains less than 49% by mass of the first non-cellulose based polymer.  
     
     
       29. The membrane according to claim 28, wherein the first and second non-cellulose-based polymers are selected from the group consisting of a thermoplastic homopolymer, a thermoplastic copolymer, an elastomeric polymer, a polyimide polymer, an aromatic polyamide polymer, a liquid crystalline polymer, a textile polymer, an electrically conductive polymer, and a biocompatible polymer and copolymers thereof.  
     
     
       30. The membrane according to claim 28, wherein the first and second non-cellulose-based polymers are selected from the group consisting of a vinyl polymer, a polyether, an acrylic polymer, a polyester, a polycarbonate, a polyurethane, an ethylene-propylene-diene-elastomer, a polyimide, a polysaccharide, a polyamide, a polylactide, a poly(p-phenylene terephthalamide), a polyaramid, a polyethylene terephthalate, a polyacrylonitrile, a polyaniline, a polycaprolactone, a polyglycolide, a polyethylene oxide, a poly(vinylpyrrolidone), a poly(vinyl acetate), a poly(vinyl alcohol), a polystyrene, a poly(methyl methacrylate), a protein, and copolymers thereof.  
     
     
       31. The membrane according to claim 21, wherein the plurality of pores comprises macropores, micropores, or a combination thereof.  
     
     
       32. The membrane according to claim 21, wherein the pores have a uniform size distribution as determined by scanning electron microscope (SEM).  
     
     
       33. The membrane according to claim 21, further comprising regenerating the derivatized cellulose.  
     
     
       34. The membrane according to claim 33, wherein the regenerating and removing are simultaneous.  
     
     
       35. The membrane according to claim 21, further comprising a step of adding the membrane to a column or a vessel.  
     
     
       36. A method of preparing a membrane comprising:
 providing an electrospun nanofiber felt comprising a composite nanofiber and a single component nanofiber,
 wherein the composite nanofiber comprises a mixture of a derivatized cellulose and a first non-cellulose-based polymer, and 
 wherein the single component nanofiber comprises a second non-cellulose-based polymer, 
 wherein the first and second non-cellulose-based polymers are differentially removable from the nanofiber felt; 
   removing the first or second non-cellulose-based polymer from the nanofiber felt to form the membrane, which has a plurality of pores.    
     
     
       37. The method of claim 36, wherein the plurality of pores comprises macropores, micropores, or a combination thereof.  
     
     
       38. The method of claim 36, wherein the pores have a uniform size distribution as determined by scanning electron microscope (SEM).  
     
     
       39. The method of claim 36, further comprising a step of regenerating the derivatized cellulose.  
     
     
       40. The method of claim 39, wherein the regenerating and removing are simultaneous.  
     
     
       41. The method of claim 36, further comprising a step of adding the electrospun membrane to a column or a vessel.