FILTRATION MEMBRANES

1 - 23 . (canceled)

24 . A method for maintaining pore size of a reusable filtration membrane comprising exposing the filtration membrane to a plasma comprising a hydrocarbon or fluorocarbon monomer to form a polymeric layer on a surface of the filtration membrane.

25 . The method of claim 24 , further comprising subjecting the reusable filtration membrane to caustic washing.

26 . The method of claim 24 , wherein the reusable filtration membrane consists essentially of synthetic polymeric material.

27 . The method of claim 26 , wherein the synthetic polymeric material consists essentially of polyethylene.

28 . The method of claim 24 , wherein the plasma is pulsed.

29 . The method of claim 28 , further comprising, in a preliminary step, applying a continuous power plasma to the filtration membrane.

30 . The method of claim 24 , wherein the monomer is a compound of formula (I)

where R 1 , R 2 and R 3 independently are selected from hydrogen, alkyl, haloalkyl or aryl optionally substituted by halo; and R 4 is a group X—R 5 where R 5 is an alkyl or haloalkyl group and X is a bond, a group of formula —C(O)O(CH 2 ),Y— where n is an integer of from 1 to 10 and Y is a bond or a sulphonamide group, or a group —(O) p R 6 (O) q (CH 2 ) t — where R 6 is aryl optionally substituted by halo, p is 0 or 1, q is 0 or 1, and t is 0 or an integer from 1 to 10, provided that where q is 1, t is not 0.

31 . The method of claim 30 , wherein the compound of formula (I) is a compound of formula (II)

CH 2 ═CH—R 5   (II)

where R 5 is an alkyl or haloalkyl group.

32 . The method of claim 30 , wherein the compound of formula (I) is a compound of formula (III)

CH 2 ═CR 7a C(O)O(CH 2 ),R 5   (III)

where n is an integer of from 1 to 10, R 5 is an alkyl or haloalkyl group, and R 7a is hydrogen, C 1-10 alkyl, or C 1-10 haloalkyl.

33 . The method of claim 32 , wherein the compound of formula (III) is a compound of formula (IV)

where R 7a is hydrogen, C 1-10 alkyl, or C 1-10 haloalkyl, and x is an integer of from 1 to 9.

34 . The method of claim 33 , wherein the compound of formula (IV) is 1H,1H,2H,2H-heptadecafluorodecylacylate.

35 . The method of claim 24 , further comprising placing the reusable filtration membrane in a plasma deposition chamber, igniting a glow discharge within the chamber, and applying a pulsed voltage.

36 . The method of claim 35 , wherein the voltage is applied at a power of from 40 to 500 W.

37 . The method of claim 35 , wherein the voltage is pulsed in a sequence in which the ratio of time on to time off is from 1:500 to 1:1500.

38 . The method of claim 35 , further comprising, in a preliminary step, applying a continuous power plasma to the filtration membrane.

39 . The method of claim 38 , wherein the preliminary step is conducted in the presence of an inert gas.

40 . The method of claim 36 , wherein the voltage is pulsed in a sequence in which the ratio of time on to time off is from 1:500 to 1:1500, the reusable filtration membrane consists essentially of a polyethylene material, and the monomer is 1H,1H,2H,2H-heptadecafluorodecylacylate.

41 . A reusable filtration membrane consisting essentially of a synthetic polymeric material that has been treated with a plasma comprising a hydrocarbon or fluorocarbon monomer to form a polymeric layer on a surface of the filtration membrane.

42 . The reusable filtration membrane of claim 41 , wherein the synthetic polymeric material consists essentially of a polyethylene material.

43 . A method of filtering a liquid comprising passing the liquid through a filtration membrane consisting essentially of a synthetic polymeric material that has been treated with a plasma comprising a hydrocarbon or fluorocarbon monomer to form a polymeric layer on a surface of the filtration membrane.

44 . The method of claim 43 , further comprising a subsequent step of washing the filtration membrane in a caustic solution.