A method of enhancing hydrophilicity of a hydrophobic polymer material includes pre-treating the hydrophobic polymer material, comprising treating the hydrophobic polymer material with a first atmospheric pressure plasma discharge in a first atmosphere. The first atmosphere includes ammonia to obtain a pre-treated polymer material. The method includes treating the pre-treated polymer material with a second atmospheric pressure plasma discharge in a second atmosphere in which an aerosol of a carboxylic acid is introduced. A substrate is provided as well, the substrate including a hydrophobic polymer material having a modified interface, wherein the modified interface includes carboxylic functional groups grafted on the hydrophobic polymer material, the modified interface having a contact angle with water, which, measured after immersion in water at 20° C. for 3 days, is at least 25° less than a contact angle with water of the hydrophobic polymer material.