Electrospinning of ptfe with high viscosity materials

Abstract

An improved process for forming a PTFE mat is described. The process includes providing a dispersion with PTFE, a fiberizing polymer and a solvent wherein said dispersion has a viscosity of at least 50,000 cP. An apparatus is provided which comprises a charge source and a target a distance from the charge source. A voltage source is provided which creates a first charge at the charge source and an opposing charge at the target. The dispersion is electrostatically charged by contact with the charge source. The electrostatically charged dispersion is collected on the target to form a mat precursor which is heated to remove the solvent and the fiberizing polymer thereby forming the PTFE mat.

What is claimed is: 
     
         1 . A combination comprising:
 a surface formed of metal, ceramic or polymeric material; and   a layer of electrospun polytetrafluoroethylene (PTFE) on the surface.   
     
     
         2 . The combination of  claim 1 , wherein the surface is a device and the electrospun PTFE is sintered in place on the device. 
     
     
         3 . The combination of  claim 1 , wherein the surface is formed of metal. 
     
     
         4 . The combination of  claim 3 , wherein the surface is a device of metal material selected from the group consisting of stainless steel, cobalt chrome, nickel titanium (Nitinol), and magnesium alloys. 
     
     
         5 . The combination of  claim 4 , wherein the surface is cylindrical and the electrospun PTFE defines a tube sintered in place on the device. 
     
     
         6 . The combination according to  claim 1 , wherein the electrospun PTFE has been electrospun from a dispersion having a viscosity of at least 50,000 cP and comprising PTFE, a fiberizing polymer and a solvent. 
     
     
         7 . A combination comprising:
 a cylindrical surface formed of metal, ceramic or polymeric material; and   and a coating of electrospun polytetrafluoroethylene (PTFE) on the cylindrical surface,   wherein the electrospun PTFE has been electrospun from a dispersion having a viscosity of at least 50,000 cP and comprising PTFE, a fiberizing polymer and a solvent.   
     
     
         8 . The combination of  claim 7 , wherein the cylindrical surface is a device formed of metal material selected from the group consisting of stainless steel, cobalt chrome, nickel titanium (Nitinol), and magnesium alloys, and the coating is sintered in place on the device. 
     
     
         9 . An electrospinning process comprising: electrospinning polytetrafluoroethylene (PTFE) onto a cylindrical surface and, thereafter, sintering the electrospun PTFE while in place on the cylindrical surface. 
     
     
         10 . The process of  claim 9 , wherein the sintering comprises placing in an oven the entire cylindrical surface with the electrospun PTFE thereon. 
     
     
         11 . The process of  claim 9 , wherein the spinning comprises covering the entire cylindrical surface with the electrospun PTFE and the sintering comprises placing the entire covered cylindrical surface in an oven. 
     
     
         12 . The process of  claim 9 , wherein electrospinning PTFE onto the cylindrical surface comprises:
 applying a voltage to establish an electrical charge differential between a charge source and the cylindrical surface;   electrostatically charging a dispersion wherein the dispersion is electrostatically charged by the charge source, and wherein the dispersion comprises PTFE, a fiberizing polymer, and a solvent; and   collecting the electrostatically charged dispersion on the cylindrical surface.   
     
     
         13 . The process according to  claim 9 , wherein electrospinning PTFE onto the cylindrical surface comprises electrospinning from a dispersion comprising PTFE, a fiberizing polymer and a solvent, wherein the dispersion has a viscosity of at least 50,000 cP.