Ryan M. Hensarling

Synthesis of multifunctional polymer brush surfaces via sequential and orthogonal thiol-click reactions

Fabrication of multifunctional surfaces with complexity approaching that found in nature requires the application of a modular approach to surface engineering. We describe a versatile post-polymerization modification strategy to synthesize multifunctional polymer brush surfaces via combination of surface-initiated photopolymerization (SIP) and orthogonal thiol-click reactions. Specifically, we demonstrate two routes to multifunctional brush surfaces: in the first approach, alkyne-functionalized homopolymer brushes are modified with multiple thiolsvia a statistical, radical-mediated thiol-yne co-click reaction; and in the second approach, statistical copolymer brushes carrying two distinctly-addressable reactive moieties are sequentially modified via orthogonal base-catalyzed thiol-X (where X represents an isocyanate, epoxy, or α-bromoester) and radical-mediated thiol-yne reactions. In both cases, we show that surface properties, in the form of wettability, can be easily tuned over a wide range by judicious choice of brush composition and thiol functionality.

Thiol–isocyanate “click” reactions: rapid development of functional polymeric surfaces

Functional, micropatterned and multicomponent polymer brush surfaces can be rapidly fabricated via base-catalyzed thiol–isocyanate “click” reactions.

Rapid Synthesis of Polymer Brush Surfaces via Microwave-Assisted Surface-Initiated Radical Polymerization

Microwave-assisted surface-initiated radical polymerization (μW-SIP) is demonstrated for the rapid synthesis of polymer brush surfaces on two-dimensional substrates. μW-SIP is carried out at constant temperature and microwave power allowing comparison with conventional SIP carried out in an oil bath at the same effective solution temperature. We show μW-SIP enables significant enhancements (up to 39-fold increase) in brush thickness at reduced reaction times for a range of monomer types (i.e. acrylamides, acrylates, methacrylates, and styrene). The effects of reaction time, monomer concentration, and microwave power on film thickness are explored.

CHAPTER 12:Surface Engineering with Thiol‐click Chemistry

Thiol-click chemistry has emerged as a powerful approach to engineer the chemical composition of surfaces with high efficiency and modularity. This chapter provides a comprehensive review of literature examples employing thiol-based reactions to modify the surfaces of self-assembled monolayers, polymer surfaces, microporous membranes, nano- and microparticles, and biological surfaces. Although all thiol-based transformations are represented, much of the surface modification literature to date has focused on the radical-mediated thiol-ene and thiol-yne reactions and thiol-Michael reactions to fabricate surfaces with complex, but well-defined chemistries. The primary purpose of this chapter is to illustrate the clear potential and broad utility of thiol-click chemistry for surface engineering applications.