The aim of this paper is to study the interaction between alcoholic solutions of different polarities and a new class of packaging polymer, the cycloolefins, which can be used in pharmaceutical and cosmetic fields. Different consequences of this interaction were studied as adjuvant migration, and polymer swelling. Very extreme storage conditions were used to accelerate the ageing of the polymer. This study shows the great influence of solvent polarity on the material's thermomechanical properties as well as on its barrier properties. (c) 2007 Wiley Periodicals, Inc.