Plasma Surface Modification of Polycarbonate and Poly(propylene) Substrates for Biomedical Electrodes Paulo Pedrosa, Jean-Marie Chappe ´, Carlos Fonseca, Ana Vera Machado, Joa ˜o Miguel No ´brega, Filipe Vaz* Introduction Polymeric materials have a wide range of applications due to several advantages, such as flexibility, light weight, low cost and processability. Furthermore, a polymeric surface may be functionalized, for example by thin film deposi- tion, [1–3] widening even more the application range for these materials in several areas of technological relevance, e.g. headlights, lenses or antibacterial packages. [4–6] None- theless, thin film coating of polymeric surfaces results very often in some critical problems, including the well-known lack of adhesion. [7] In fact, the optimization of the adhesion between thin metallic or ceramic films and common polymers represent some of the most relevant challenges in recent R&D projects, due to the very Full Paper P. Pedrosa, J.-M. Chappe ´, F. Vaz Universidade do Minho, Centro de Fı ´sica, Campus de Azure ´m, 4800-058 Guimara ˜es, Portugal E-mail: fvaz@fisica.uminho.pt C. Fonseca INEB – Instituto de Engenharia Biome ´dica, Divisa ˜o de Biomateriais; Universidade do Porto, Rua do Campo Alegre, 823, 4150-180 Porto, Portugal C. Fonseca Universidade do Porto, Faculdade de Engenharia, Departamento de Engenharia Metalu ´ rgica e de Materiais, Rua Roberto Frias, s/n, 4200-465 Porto, Portugal A. V. Machado, J. M. No ´brega Universidade do Minho, Centro Eng. a de Polı ´meros, Campus de Azure ´m, 4800-058 Guimara ˜es, Portugal The effects of surface plasma treatments on the properties of PP and PC substrates were studied. Main results showed that the 0.48 Pa Ar treatment promoted the most favorable changes: roughness increased from 15 to 17 nm for PC and from 12 to 30 nm for PP, while the CA lowered from 958 to 598 and from 878 to 358 for PC and PP, respectively. The effects of the activation treatment on adhesion were checked by depositing a thin layer of TiN on both untreated and 0.48 Pa Ar plasma treated PC samples, and the adhesion to both substrates compared using the standard X-cut tape test. The Ar activated samples displayed better adhesion of the TiN film than the untreated ones, confirming the benefits of the surface changes induced by the plasma treatments. 676 Plasma Process. Polym. 2010, 7, 676–686 ß 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim DOI: 10.1002/ppap.200900176