Enhanced elasticity in parylene thin films by copolymerization approach

The application of poly(p-xylylene)s as barrier and passivation layer is limited by the high tensile modulus of this class of materials. In this view, we propose a modified chemical vapor deposition approach to realize a series of copolymers based on parylene C, where linear alkyl chains partially replace the chlorides substituents. Thanks to the efficacious inclusion of bulky alkyl chains into the parylene layer, these modified materials show clear differences in both thermal and mechanical properties with respect to pristine parylene C. In particular, by following this approach, a decrease of the Young's modulus up to 0.3 GPa (13 times reduction of parylene C modulus) is observed, indicating a neat enhancement of the elastic behavior. Besides the improved mechanical performance, the modified materials retain both barrier and biocompatibility properties typical of neat parylene C. The results presented support copolymerization as a valuable approach for tuning parylene properties, which enlarges further the field of application of this excellent multipurpose material.