Combination of Circular PDMS Mold and Gasbag Roller to Replicate Continuous Anodic Aluminum Oxide Nano Structures by UV Resin on PC Film
Date Issued
2012
Date
2012
Author(s)
Lee, Yun-Heng
Abstract
Nanostructured thin films have been widely applied for anti-reflective components, bio-sensing and self-cleaning surfaces. The roller molds for production of nanostructured films mostly are made by expensive processes, such as e-beam or focused ion beam, or by wrapping the electroplated mold on the roller. Cost and complication are problems. Furthermore, the contact between the rigid roller and the substrate is nearly a line; the brief contact prevent perfect replication at high rolling speed. This study develops an effective, fast, and low-cost method to fabricate seamless anodic aluminum oxide (AAO) roller mold. Circular PDMS (polydimethylsiloxane) mold with nanostructures is then cast from the AAO roller mold and used as the mold. A facility combining UV-based imprinting technique, gasbag-roller and circular PDMS mold, has been designed and implemented to replicate nanostructures on the surface of polycarbonate (PC) continuously. The gasbag-roller is employed to increase the contact area and to ensure the conformity of contact between the mold and the substrate.
The AAO roller mold is made by 2-step anodization process from a 99.9% purity circular aluminum tube, and the nano-pores are fabricated in the internal wall of the tube. The outer and inner diameters are 66mm and 60mm respectively, and the length is 50mm. The SEM photos show that the fabricated nanopores are similar as observed from all degrees of the surface.The alumina oxide membranes with nanopores of 220 nm and 430 nm in pitch and 160nm and 230nm in nanopore size are fabricated with anodization voltages of 80 V and 180 V, respectively. Nano pillars have been fabricated on the surface of circular PDMS mold by micro-casting. The circular PDMS mold with nanostructures is sustained by a gasbag roller.
With aid of pressure sensitive films, it is verified that the combination of the gasbag-roller and the PDMS mold not only increases the contact area between roller and substrate, but also enhances the pressure uniformity over the contact area. The quality and speed of replication thus can be greatly improved. The effects of mold and viscosity of UV curable resin in the roller imprinting process have been investigated. The nanostructures can be successfully fabricated on the PC film with appropriate inner gas pressure in the gasbag and external pressure applied on the shaft.
The antireflection and the hydrophobic effect of the fabricated PC film have been measured. The reflection has been dropped from 14.77% in the bare PC film to 2% in the PC film with AAO nanostructures. The contact angle has increase from 77.5° in the bare PC film to 124.1° in the PC film with AAO nanostructures. The results prove that an effective replication facility and process has been developed for fast and effective replication of nanostructures.
Subjects
gasbag roller
Anodic Aluminum Oxide
nano imprinting
UV resin
Type
thesis
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