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Saswati Pujari


Current Position: Electrical and Telecommunications Division, The Dow Chemical Company

Undergraduate Institution: IIT Kharagpur

Graduate Institution: Northwestern (Advisor: Wesley Burghardt)

Princeton Postdoctoral Research:

     While thin films of cylinder-forming block copolymers (BCPs) can be effective templates for striped patterns (leading to parallel nanowires), a drawback is the modest aspect ratio of the final structures, because of limited etch contrast between the two polymer blocks. Using thin films of lamellar BCPs, with the lamellae standing perpendicular to the substrate, could yield structures with larger aspect ratio. To generate parallel stripes of controlled direction, the in-plane orientation needs to be guided while preserving the out-of-plane perpendicular orientation. In this study, we have produced thin films of standing lamellae of a polystyrene/polymethylmethacrylate BCP of thicknesses up to 1.5 times the domain spacing, by neutralizing the Si substrate with a random terpolymer brush layer. These perpendicular lamellae are shear aligned to induce long range order. We are currently investigating the alignment as a function of stress, film thickness, terpolymer composition and domain spacing.