Solvent-vapor-assisted imprinting lithography (SVAIL) using a 1 mm thick flexible polydimethylsiloxane (PDMS) membrane mold as a solvent transport medium in a vapor environment is demonstrated. By adjusting the solvent vapor pressure, this transport mechanism provides a sufficient amount of solvent to soften the thin polystyrene resist (<100 nm) and avoids the deformation of imprinted nanopatterns due to excess solvent that is problematic with other methods. The results show that SVAIL has potential for large-area patterning because the molding of the softened polymer can be performed without external loading. Localized molding and conformal contact with a curved surface allow multiple imprinting to be performed to obtain more complex, two-dimensional hierarchical structures using simple stripe-patterned stamps.

In this article, a simple and cost-effective method to create patterned nanoindentations on Al surface via mold-assisted chemical etching process is demonstrated. This report shows the reaction-diffusion method which formed nanoscale shallow etch pits by the absorption/liberation behaviors of chemical etchant in poly(dimethylsiloxane) stamp. During subsequent anodization, it was possible to obtain the ordered nanopore arrays with 277 nm pitch that were guided by the prepatterned etch pits. The prepatterned etch pits obtained can guide the growth of AAO nanopores during anodization and facilitate the preparation of ordered nanopore arrays.

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In this paper, polymethylmethacrylate (PMMA) and ethyl alcohol (EtOH) were chosen for demonstrating a solvent-assisted imprint process working at room temperature and low pressure (∼0.01 MPa) with a soft mold. The poor solvent molecules, EtOH, cause a physical swelling reaction in both the PDMS mold and the PMMA resist. The swollen PMMA gel has excellent filling capability for application in imprinting lithography. During imprinting the PDMS mold absorbs the poor solvent in the resist by swelling, which deswells the PMMA gel and helps pattern setting. This new idea can be applied extensively to the micro-/ nanoimprint lithography and plastics industry to prepare micron and nanometer scale structures. Additionally, by controlling the imprinting conditions, we can get a residual-layer-free pattern through the phenomenon of polymer dewetting.

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