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Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Polymer Science and Engineering

Year Degree Awarded

2016

Month Degree Awarded

September

First Advisor

Kenneth R. Carter

Subject Categories

Engineering | Materials Science and Engineering

Abstract

Micro-/nanofabrication finds wide use in the preparation of patterned surfaces, which are of vital importance in the applications of functional surfaces, electronics, optics, and sensors. This dissertation will present the preparation of ultrafine structures and functional surfaces over large areas utilizing a combination of top-down lithography technique and bottom-up wrinkling method.

First, a simple, scalable and cost-effective spacer lithography approach utilizing polydopamine coating technique was developed for the fabrication of well-controlled nanopatterns with feature size in the sub-20 nm scale. Briefly, a thin layer of polydopamine (PDA) was conformally deposited on the sidewalls of pre-patterned poly (methyl methacrylate) (PMMA) features to form a spacer layer. After etching the PDA film on the horizontal surfaces and removing the PMMA resist, only the PDA spacer was left on the substrate, forming a new pattern. The pattern density of the new features was doubled and the feature size was well tuned to a sub-20 nm scale.

We also utilized a bottom-up wrinkling technique to spontaneously pattern and functionalize polymer films. Through a reactive silane-infusion induced surface instability, wrinkled patterns with tunable wavelengths were easily produced over large areas and the surface chemical functionality of the wrinkles was well-tuned by the infusion of different functional silanes. Hierarchically wrinkled patterns with micro/nano structure were achieved by combining wrinkling with nanoimprint lithography. The hierarchically wrinkled surfaces exhibited superhydrophobicity with water contact angles higher than 160°and water sliding angle lower than 5°.

To scale up these patterned functional surfaces over large areas, roll-to-roll nanoimprint lithography technique was investigated for the continuous fabrication of superhydrophobic surfaces and lubricant infused patterned surfaces based on hierarchically wrinkled surfaces. These functionally patterned surfaces displayed self-cleaning properties to a variety of liquid contaminations and anti-biofouling properties when challenged with Escherichia coli bacteria. This study suggested a potential transformation of artificial biomimetic structures from small, lab scale coupons to low cost, large area platforms.

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