Parylene C composite film modified by nanosilica/titania for enhancement of thermal stability and UV stability

• A special customed chemical vapor deposition system (PSD2010) is presented.
• The SiO2 and TiO2 nanoparticles are modified by silane coupling agent.
• Argon plasma treatment is applied to improve the binding force of Parylene C.
• The thermal stability, mechanical strength and UV stability of the film are improved.

The Parylene C composite film modified by nanosilica/titania is introduced. This composite film is prepared by depositing Parylene C film as the support layer (8 μm) on substrate firstly, then spraying the modified nanoparticle functional layer (SiO2: 0.01 mol/L, TiO2: 0.01 mol/L), and then treating the surface by plasma to improve the surfactants, finally depositing Parylene C on the surface of these nanoparticles as the fixed layer (6 μm). Nanosilica/titania particles are treated by silane coupling agent to obtain a good dispersion; the size of the nanoparticles is about 150–200 nm. The thermoplastic deformation critical temperature of modified composite film is 103.4 °C, which is higher than the pure film deformation temperature of 73.6 °C. The effective modulus of the modified composite film is 13.54 GPa compared to the 1.67 GPa of the pure film. The ultraviolet absorption ability of the modified composite film basically remains unchanged after 8 hour UV irradiation while the ultraviolet absorption of pure film has fallen by about 34.9%. The thermal stability, mechanical properties and UV stability of the modified Parylene C composite film have been improved, which will expand the application field of the modified Parylene C film. Meanwhile, the Parylene C composite film with other functions can be realized by using different nano-materials.