The Distribution of CH₃ Over the Film Thickness and Shrinkage of H₂ Plasma‐Modified PDMS Films

Abstract

The H 2 plasma modification of polydimethylsiloxane (PDMS) films of initial thickness up to 600 nm was studied. The main plasma component modifying the films is the VUV plasma radiation measured by a VUV monochromator. By variation of the plasma processing parameters, such as H 2 pressure, RF forward power and treatment time, the optimum parameters are defined for the plasma chemical modification of liquid PDMS films. The thin films were analysed by Infrared Reflection Absorption Spectroscopy. Gradually changes in the vertical films structures is found with a top methyl-free SiO x layer ( 60 nm), followed by a crosslinked bulk material with a gradually increasing CH 3 concentration over the film depth. Additionally, the PDMS plasma modifications results in films shrinkages as measured by Spectroscopic Ellipsometry (SE).

Effect of plasma surface treatment of poly(dimethylsiloxane) on the permeation of pharmaceutical compounds

“…One particularly interesting modification to standard PDMS that has been the subject of investigation in recent years is modification of the surface using plasma treatment. It is generally accepted that PDMS (upon exposure to plasma) develops silanol groups (–OH) at the expense of methyl groups (–CH 3 ) [16] , [17] as a result of oxidation of the surface layer [18] . This creates a more highly hydrophilic surface which can be observed through a reduction in the contact angle of water [19] and may cause a wrinkling effect under certain conditions [20] .…”