The use of an aqueous Solution comprising at least one polyanion and at least one high molecular weight polyethyleneimine is described, for providing oxygen barrier properties to a polymer film. The polyanion is a polymer comprising acid groups neutralized with a base selected from the group consisting of inorganic bases and monovalent organic bases and having a weight average molecular weight of at least 10000 g/mol.

A polyurethane or polyurea coating composition for use in protecting a leading edge substrate on an airfoil, such as aircraft wings, rotor blades and propeller blades, against liquid or solid particle erosion, the composition made from an isocyanate-terminated prepolymer and curing agents, such as polyaspartic esters, aldimines and ketimines.

A polyurethane or polyurea coating composition for use in protecting a leading edge substrate on an airfoil, such as aircraft wings, rotor blades and propeller blades, against liquid or solid particle erosion, the composition made from a polyisocyanate and curing agents, such as polyaspartic esters, aldimines and ketimines, polyamines and polyols or mixtures thereof with optional flatting agent for matte coatings.