Material selection for sealing component

Im exploring the possibility of using an elastomeric foam for a sealing component.

The seal is for use in a cannula or tube, to form a pressure barrier between spaces,
and adapted to accommodate instrument diameters ranging from 5 to 12 mm passed through.

Essentially a plug with a small central orifice, slightly smaller than 5 mm.
The foam should compress and displace according to the diameter of the instrument placed through.

Any suggestions or recommendations for such material are greatly appreciated.

Thanks