Date of Award

Spring 2019

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

School

Polymer Science and Engineering

Committee Chair

Derek L. Patton

Committee Chair School

Polymer Science and Engineering

Committee Member 2

Sarah E. Morgan

Committee Member 2 School

Polymer Science and Engineering

Committee Member 3

Robson F. Storey

Committee Member 3 School

Polymer Science and Engineering

Committee Member 4

Sergei I. Nazarenko

Committee Member 4 School

Polymer Science and Engineering

Committee Member 5

Yoan C. Simon

Committee Member 5 School

Polymer Science and Engineering

Abstract

The combination of surface-initiated polymerization (SIP) and post-polymerization (PPM) serves as a powerful approach to fabricate complex, multifunctional polymer films, which can be precisely tuned for desired surface engineering applications. Careful manipulation of PPM parameters such as reaction conditions, the tethered brush parameters, and the physical properties of the unbound post-modifier greatly influence the depth of penetration of the post-modifier and the polymer brush compositional heterogeneity. This dissertation focuses on engineering polymer brush surfaces with multifunctional chemistries and tunable morphologies by investigating the PPM parameters that dictate the distribution of post-modifiers on grafted polymer brush surfaces.

The first chapter of this dissertation outlines the benefits of SIP and PPM for the design of complex polymer surfaces. Furthermore, this chapter explains the motivation for designing complex, functional polymer surfaces with tunable morphologies from the nanometer to micron scale.

In the second chapter, microwave-assisted surface-initiated polymerization is exploited to prepare poly(acrylamide-homocysteine thiolactone) (pAHT) brushes. The pAHT brushes serve as a powerful platform to undergo sequential and one-pot amine-thiol-ene conjugation reactions. XPS depth profile experiments provided insight into the modified pAHT brush through-thickness composition and PPM efficiency (e.g. sequential versus one-pot reactions).

The third chapter focuses on a simple PPM approach to engineer buckling instabilities (e.g. wrinkles) in ultrathin (< 100 nm) poly(styrene-alt-maleic anhydride) (pSMA) brush surfaces. The wrinkled morphologies were judiciously tuned by PPM reaction time and anhydride conversion. Partial cross-linking of the outer layer of the pSMA brushes under poor solvent conditions is critical to obtain the wrinkled morphologies upon swelling. ToF-SIMS depth profiling and in situ ellipsometry provided insight into the parameters that influence the buckling behavior.

In the fourth chapter, an expression to quantify the applied compressive strain was derived for bilayer systems where the strain is unknown. The expression was validated using a prototypical bilayer model system (e.g. polystyrene on polydimethylsiloxane). Next, the expression was used to quantify the strain of the wrinkled pSMA brushes in the previous chapter. Finally, the calculated strain values of the wrinkled pSMA brushes were corroborated using the relationship between applied strain and persistence length of aligned wrinkles.

ORCID ID

0000-0002-4030-2017

Available for download on Monday, May 10, 2021

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