Application of the polymer material polysilazane as a barrier layer

Barrier layers, especially those that provide a barrier to gases such as water vapor, are a common type of coating on the surfaces of electronic and optical devices. In one study, a barrier layer was developed using PHPS, and this barrier layer, together with an adhesive layer, formed an adhesive sheet. The barrier layer had a surface density ranging from 2.4 to 4.0 g-cm-³, with 60% to 75%, 0% to 10%, and 25% to 35% oxygen, nitrogen, and silicon, respectively, which was one of the early patents for the development of barrier layers using PHPS. Another study examined the effect of PHPS structure on gas barrier properties and found that by adjusting the ratio of SiH3 to SiH and SiH2 to 1:(10 to 30), a gas barrier film with excellent stability under high temperature and high humidity conditions could be produced.
In addition to using PHPS alone, it is often used in combination with a modified material to prepare a barrier layer. For example, silicone-containing membranes with the structural formula SiOxNyMz have been prepared using PHPS together with metal compounds such as aluminum tri-sec-butoxide, showing excellent stability under high temperature and high humidity conditions. Another study described the use of several additives in combination with PHPS, including hydrocarbon-substituted guanidines, oxygen-nitrogen-containing crown ether amines, amino-substituted cycloalkanes with polycyclic structures, and hydrocarbon-substituted oximes, which significantly enhanced the gas barrier properties of the resulting membranes.
The composition of the solution also has an effect on the performance of the PHPS barrier layer, which can be made soluble in aliphatic hydrocarbon solvents by limiting the specific structural units and the ratio of Si-R bonds relative to Si-H bonds of PHPS to prepare silica-like glassy barrier layers with low water vapor transmission rates.
In addition, the effect of the preparation method on the properties of the barrier layer was also the focus of the study. Barrier films with specific refractive index ranges were prepared using heating and plasma treatment, while films with excellent gas barrier properties and phase difference film function were prepared on various polymer substrates using PHPS under vacuum UV irradiation. Finally, SaSaki et al. investigated the effects of vacuum ultraviolet (VUV)-induced Si-N bond number, PHPS film composition, and free volume on the membrane densification process, and found that VUV irradiation promotes the rapid release of hydrogen and the densification of membranes, which provides valuable guidance for the development of nanosized SiN thin films with high density and excellent gas barrier properties.