The invention provides a new polymeric material coated by a cationic polymer, which is active as an anti-bacterial product and has low permeability for non-polar solvents. The coated polymeric material may be obtained by activating the surface of a polymeric carrier material by atmospheric-pressure plasma, treating the activated polymeric carrier material with a concentrated solution of a polymerizable quaternary phosphonium or ammonium salt, and polymerizing the quaternary phosphonium or ammonium salt by action of heat.