Interfacial and Wetting Considerations in High Throughput Nanoscale 3-D Transfer Molding

Assembly of soft matter into three-dimensional structures at the nanoscale holds promise in fields including microfluidics and photonics, and transfer molding offers a low-cost, large-area approach to patterning such structures. In transfer molding, an ink is coated into a nano-patterned stamp, cured, and transferred to a substrate in a layer-by-layer fashion. We studied wetting, surface treatment, and adhesion in the context of continuous processing techniques with a focus on selective filling of stamps, a size scale dependence on adhesion following plasma exposure, and comparison of batch and continuous surface treatments. Residual-layer-free transfer molding was achieved through identification of wetting regimes related to the coating process combined with plasma doses orders of magnitude lower than the optimal dose suggested in prior literature on plasma bonding. Comparison of plasma treatment and corona discharge treatment for multi-layer adhesion further underscored the importance of brief surface treatments for both process throughput and stamp lifetime. This work brings transfer molding to new size scales, opening new opportunities for research in low-cost, multi-layer nano-patterning.