Solvent-assisted and thermal wrinklings of argon plasma treated polystyrene coatings on silicon substrate

We report results of preparation of wrinkled polystyrene (PS) surfaces on silicon substrate employing two different methods, solvent-assisted wrinkling (SAW) and thermal wrinkling (TW). In both methods an argon (Ar) plasma treatment of PS/silicon bi-layer by reactive ion etching (RIE) was used for creation of cross-linked PS layer acting as a capping layer. In SAW method the layered system was exposed after the plasma treatment to solvent vapor and in TW method the layered system was heated above the glass-transition temperature of PS employed. Wave-like patterns were achieved with the both initiation methods and using the two polystyrenes having different molar masses. The plasma treatment time was found to have influence on the wrinkle formation by affecting the thickness of the cross-linked part of PS layer, and influencing slightly the dimensions of the wrinkles. The molar mass of PS was found to have effect on overall size-scale of the forming patterns. Moreover, employing TW as a wrinkling method yielded somewhat higher wrinkles.