Simultaneous Improvement of Surface Properties of the Liquid Silicone Rubber by Direct Fluorination

In this report, liquid silicone rubber (LSR) was fluorinated and studied. ATR-IR and XPS results clearly indicate the presence of Si-F bonds as well as C-F bonds in the fluorinated layer. The fluorination of the LSR is not a simple substitution of fluorine atoms for hydrogen atoms of methyl groups or for methyl groups, and during the fluorination besides fluorine atoms there are other reactive species, such as methyl derivatives and their fluorides, which would be also attached to Si or graft to methyl groups via hydrogen replacement. The experimental results show that the fluorinated surface is highly hydrophobic and partially conductive. The flashover tests using a sheet sample/finger electrode arrangement found a more than 60% increase in DC flashover voltage of the LSR material by the fluorination. The simultaneous improvement of surface properties is meaningful for outdoor insulation applications of the material.