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Ranulfo Allen '08


Current Position: Research Analyst, Frost & Sullivan

B.S.E. Thesis Research:

Several methods of aligning block copolymer thin films have been discovered and examined thoroughly. These include simple shearing, use of an electric field, and pre-patterning of a substrate. Of the available alignment techniques, only pre-patterning of the substrate allows for complex patterning. However, this technique requires expensive lithography techniques such as electron-beam lithography. In addition, this technique is limited in feature size. Electron-beam lithography can reach feature sizes of about thirty nanometers, but at this size, the fidelity of the sample suffers and the pattern can only be applied to a small area. Block copolymers produce feature sizes on the magnitude of tens of nanometers over a large area, on the order of centimeters. One alignment technique that has not received any attention is oscillatory shearing. Oscillatory shearing of block copolymer thin films provides both the ability to create complex patterns and the small feature size. Oscillatory shearing can be applied to a specific area. This allows for a succession of targeted areas, which combine to form a complicated pattern. This research will cover the applicability of oscillatory shearing to aligning block copolymer thin films. The two-dimensional variable space has also been tested. It will be shown that oscillatory shearing requires a greater stress to provide alignment. However, when this alignment is achieved, it is comparable to simple shearing. In addition, at a particular applied stress, there seems to be a maximum frequency. Above this frequency, alignment appears to be unachievable.