Nanoimprint lithography with UV-curable hyperbranched polymer nanocomposites

Nano-scale patterns were produced with UV-curable acrylated hyperbranched polymer nanocomposites using nanoimprint lithography with a glass master in a rapid, low-pressure process. The pattern of the glass master was replicated with composites containing up to 25 vol% SiO2 with a shape fidelity better than 98%. Photo-rheology, interferometry and atomic force microscopy were used to analyze the material behavior. Attention was paid to the relationship between composition, nanoparticle dispersion, kinetics of photo-polymerisation, shrinkage, pressure and shape fidelity of nano-gratings. It was shown that the gel-point of the nanocomposite was an important factor that determined the stability as well as the dimensions of the imprinted structure. Dimensional accuracy also strongly depended on the level of internal stress, which in fact increased with the amount of silica. A resin rich layer on the surface of the composite accounted for the good surface quality of the nano-pattern. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.