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Author ORCID Identifier

https://orcid.org/0000-0003-2696-2403

AccessType

Open Access Dissertation

Document Type

dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Polymer Science and Engineering

Year Degree Awarded

2022

Month Degree Awarded

September

First Advisor

Laura C. Bradley

Subject Categories

Condensed Matter Physics | Polymer and Organic Materials | Polymer Science

Abstract

The overarching goal of the thesis is to understand growth and assembly of polymer materials at interfaces. Chapter 2 and Chapter 3 study simultaneous polymer growth and assembly at fluid interfaces, where in-situ photopolymerization and vapor phase deposition were utilized to grow polymers, respectively. Chapter 4 leverages capillary condensation to pattern polymer growth at solid substrates.

Chapter 1 provides background information on polymer materials at interfaces, and vapor phase deposition method (initiated chemical vapor deposition, iCVD) to grow polymers. This chapter also reviews polymer thin film wetting, and colloidal assemblies at interfaces.

In Chapter 2, we demonstrate the preparation of colloidal crystals at nematic liquid crystal (NLC)-air interfaces by simultaneous photopolymerization and assembly. Polymer colloids are produced by polymerization-induced phase separation of an acrylate monomer mixed in a non-reactive liquid crystal using an open-cell setup. Colloids adsorbed to the NLC-air interface form non-close-packed hexagonal crystals that cover the entire interface area. We examine the mechanism of growth and assembly for the preparation of LC-templated interfacial colloidal superstructures.

In Chapter 3, we investigate the growth of a fluorinated polymer via initiated chemical vapor deposition onto a suite of isotropic and mesogenic liquids with a range of refractive indices. The polymer morphology at fluid interfaces was found to deviate from conformal films predicted by the positive spreading coefficient, and the resulting morphology is attributed to long-range van der Waals interactions during the deposition process. Experiments systematically vary the deposition conditions and compare the liquid phase (isotropic or nematic) to evaluate the effect of kinetic factors and the liquid substrate phase on the interfacial polymer morphology and spatial organization.

In Chapter 4, we use capillary condensation to pattern polymer growth via iCVD which is a promising way to selectively grow polymers in nanoparticle (NP) packings. A two-step process (first monomer condensation, and then polymerization) was used to explore the experiment conditions where polymers can fill in the NP packings (spin-coated NPs) with no polymer coating formed on the flat surface (flat silicon wafers). Systematical experiments were conducted to evaluate the effect of deposition time, NP sizes, monomer saturation time, Pm/Psat on the composite refractive index and polymer filling fraction in the NP packings.

Lastly, Chapter 5 summarizes the conclusions for chapters above and layout the future directions of this thesis work.

DOI

https://doi.org/10.7275/30960423

Creative Commons License

Creative Commons Attribution-Noncommercial 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 4.0 License.

Available for download on Wednesday, March 01, 2023

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