POLYETHERSULFONE FIBER WEBS

1 . A fiber web, comprising:

polyethersulfone fibers with an average diameter of less than or equal to 250 nm,

wherein a relative surface area of the fiber web is greater than or equal to 80%.

2 . A fiber web, comprising:

polyethersulfone fibers with an average diameter of less than or equal to 250 nm,

wherein a relative surface area of the fiber web is greater than or equal to 75%, and wherein a measured surface area of the fiber web is greater than or equal to 25 m 2 /g.

3 . A fiber web as in claim 1 , wherein the fiber web is an electrospun fiber web.

4 . A fiber web as in claim 1 , wherein the relative surface area of the fiber web is greater than or equal to about 90%.

5 . A fiber web as in claim 1 , wherein the relative surface area of the fiber web is greater than or equal to about 95%.

6 . A fiber web as in claim 1 , wherein the measured surface area of the fiber web is greater than or equal to about 55 m 2 /g.

7 . A fiber web as in claim 1 , wherein the measured surface area of the fiber web is greater than or equal to about 95 m 2 /g.

8 . A fiber web as in claim 1 , wherein the average diameter of the polyethersulfone fibers is greater than or equal to about 20 nanometers.

9 . A fiber web as in claim 1 , wherein the relative surface area of the fiber web is less than or equal to about 100%.

10 . A fiber web as in claim 1 , wherein the measured surface area of the fiber web is less than or equal to about 200 m 2 /g.

11 . A fiber web as in claim 1 , wherein at least 75 wt % of the fiber web is polyethersulfone.

12 . A fiber web as in claim 1 , wherein a filtration efficiency of the fiber web for 4 micron diameter particles is greater than or equal to about 80% and less than or equal to about 100%.

13 . A fiber web as in claim 1 , wherein a filtration efficiency of the fiber web for 0.2 micron diameter polystyrene spheres is greater than or equal to about 75% and less than or equal to about 100%.

14 . A fiber web as in claim 1 , wherein a filtration efficiency of the fiber web for 0.3 micron diameter DOP particles is greater than or equal to 1% and less than or equal to about 40%.

15 . A filter media as in claim 1 , wherein the filter media has a Log Reduction Value of greater than or equal to about 3 and less than or equal to about 8.81.

16 . A fiber web as in claim 1 , wherein the polyethersulfone fibers of the fiber web have modified surfaces.

17 . A fiber web as in claim 14 , wherein the surfaces are modified by a chemical vapor deposition process.

18 . A filter media comprising a fiber web as in claim 1 .

19 . A filter media as in claim 18 , further comprising one or more layers.

20 . A filter media as in claim 18 , further comprising a support layer.

21 . A filter media as in claim 18 , further comprising a meltblown layer.

22 . A filter media as in claim 18 , wherein the PES fiber web is between two meltblown layers.

23 . A filter media as in claim 1 , wherein the PES fiber web is in a waved configuration.