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Document Type

Campus-Only Access for Five (5) Years

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Polymer Science and Engineering

Year Degree Awarded

2017

Month Degree Awarded

February

First Advisor

Thomas P. Russell

Subject Categories

Polymer Science

Abstract

This thesis will be focused on the thin film self-assembly and high resolution nanolithography of lamellae-forming PS-b-P2VP block copolymer. Some of the scientific and engineering problems of block copolymer self-assembly will be studied using the state-of-the-art characterization facilities including AFM, SEM and synchrotron radiation X-ray scattering, pushing forward the application of block copolymer in high resolution nanolithography, storage media, and separation membranes, etc.

The first challenge is the design of BCP with small domain spacing, which defines the resolution of BCP nanolithography. Small domain spacing can be achieved by reducing the degree of polymerization, but order-to-disorder transition happens when the critical χN is reached. In this thesis, we will first discuss the disorder-to-order transition of low molecular weight PS-b-P2VP by increasing the χ parameter using salt doping. The domain spacing of PS-b-P2VP will be pushed down one step further by design BCPs with star shape chain architecture, achieving lamellar nanostructures with sub-10 nm repeating period.

Another challenge that hampers the application of BCP is the defect in the self-assembled BCP thin film. The defects in the thin film reduces the grain sizes of BCP lattices and also brings in new challenges in lithography and pattern transfer, thus the defect density in the self-assembled BCP thin film has to be reduced. It is important to understand how the defects were generated and how it can be removed using annealing and directed self-assembly (DSA). In this thesis, in situ grazing incidence small angle X-ray scattering will be used to characterize the solvent vapor annealing of P2VP-b-PS-b-P2VP triblock copolymer in thin film. The trade-off between the in-plane and out-of-plane defect density was revealed during solvent evaporation. Furthermore, long-range ordered lamellar line patterns were prepared using directed self-assembly on patterned substrate.

Comments

Hi,

Thank you so much for the review of my dissertation. I revised my dissertation based on the review comments and hope the revised version will meet with the requirement of UMass PhD dissertation formate.

Best wishes

Zhiwei

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