Study of the hybrid parylene/PDMS material
This paper reports the mechanical behavior and barrier property of the hybrid parylene/PDMS material. The repetitive uniaxial tensile tests are done to characterize its mechanical behavior and the water vapor transmission rate is measured to evaluate its barrier property. The experimental data are in accordance with the composite material theory. A novel approach of facilitating the diffusion and penetration of parylene coatings into PDMS using in-situ heated deposition is presented. The parylene depth profiling in PDMS and 180° peel tests demonstrate that parylene deposition at elevated temperatures shows enhanced pore sealing capability. A theoretical model is proposed, featuring an infinitely long cylindrical PDMS pore model, free molecular flow and time-varying pore geometry during the deposition. There is only one unknown parameter in the model: the PDMS pore diameter. By fitting the numerical solutions of the theoretical model to the parylene depth profiling curves, the PDMS pore diameter is estimated to be ~6.02nm.