FTIR analysis of plasma polymerized SiOx films for diffusion barrier coatings of PET bottles

Michael Deilmann, Pawöhner, C. , Peter Awakowicz

Proceedings of the XXVIII International Conference on Phenomena in Ionized Gases (ICPIG), 2007. 28 (13) 721–723.


For the diffusion barrier coating of PET bottles a microwave driven, low pressure plasma reactor system was developed, which allows for a plasma treatment of the inside of bottles for different purposes e.g. plasma sterilization and diffusion barrier coatings. For the coating hexamethyldisiloxane (HMDSO), a silicon containing monomer, is used in combination with Oxygen to deposit transparent SiOx films. This paper focuses on the composition of deposited films regarding Carbon and Hydrogen content of the coating. A strong reduction of Carbon can be observed by increasing the Oxygen content of the plasma gas phase or plasma power. Hydrogen is mainly present as silanol. Additionally, homogeneity is considered and conditions for homogeneous coatings, depending on residence time of process gases, is found.