Patent ID: 7534471

Claim:
A method for modifying at least one property of an at least partially sintered expanded polytetrafluoroethylene (ePTFE) porous membrane, said method comprising the steps of: providing an at least partially sintered expanded polytetrafluoroethylene (ePTFE) membrane having interconnecting pores extending through the membrane of an average pore size no greater than 10 micron; exposing the membrane to a fluid at supercritical conditions; modifying at least one property of the membrane while the membrane is exposed to the fluid at supercritical conditions by depositing a modifier onto surfaces defining the pores in the membrane; and wherein said modifying step comprises moving a portion of the modifier into a swelled portion of the membrane material; and changing the condition of the fluid in such a manner that the membrane retains the modified property by the deposited modifier remaining on the surfaces defining the pores; and permitting said membrane to return towards its original size and configuration to absorb a portion of said modifier, wherein a portion of said absorbed modifier thereafter exudes from said membrane.