Preparation of oxygen gas barrier poly(ethylene terephthalate) films by deposition of silicon oxide films plasma-polymerized from a mixture of tetramethoxysilane and oxygen

摘要

To prepare silicon oxide (SiOx)-deposited poly(ethylene terephthalate) films with high oxygen gas barrier capability, SiOx deposition by plasma polymerization has been investigated from the viewpoint of chemical composition. Tetramethoxysilane (TMOS) is suitable as a starting material for the synthesis of the SiOx films. The SiOx deposition under self-bias, where the etching action occurs around an electrode surface, is effective in eliminating carbonaceous compounds from the deposited SiOx films. There is no difference in the chemical composition between the SiOx films deposited under self-bias and under no self-bias. The SiOx films are composed of a main component of Si-O-Si networks and a minor component of carbonized carbons. The SiOx films deposited under no self-bias from the TMOS/O2 mixture show good oxygen gas barrier capability, but the SiOx films deposited under the self-bias show poor capability. The minimum oxygen permeation rate for poly(ethylene terephthalate) films deposited SiOx film is 0.10 cm3 m-2 day-1 atm-1, which corresponds to an oxygen permeability coefficient of 1.4×10-17 cm3-cm cm-2 s-1 Hg for the SiOx film itself.