| The focus of this research was on the use of surface-confined atom transfer radical polymerization (SC-ATRP) for growing surface-tethered brushes of electrolytic or charged monomers on solid substrates. The use of SC-ATRP to produce well-defined polymer brushes from monomers with non-ionic functionalities in aprotic solvents has been well documented. Although it is possible to produce PE brushes by postpolymerization chemical conversion of some neutral brushes, this approach limits the types of PE brushes that can be produced and uses organic solvents. Thus, to more widely open the design envelope in terms of types of PE brushes that can be made and to reduce the use of organic solvents, it would be beneficial to directly synthesize PE brushes using more environmentally friendly, "green" solvents, such as water, for the reaction media. But the direct ATRP of hydrophilic monomers with ionic groups presents new challenges due to the complex interactions of the charged monomers and water with the ATRP catalyst.; In this dissertation, I report findings on SC-ATRP of charged monomers such as itaconic acid (IA), methacrylic acid (MAA) and sodium 4-styrenesulfonate (SS) in aqueous solutions. Surface-tethered polyelectrolyte brushes comprised of poly(itaconic acid) (PIA), poly(methacrylic acid) (PMAA) and poly(4-styrenesulfonate) (PSS) were grown using surface-confined atom transfer radical polymerization (ATRP). The surface-tethered initiator monolayer was formed by self-assembling 2-bromoisobutyryl bromide terminated thiol molecules on gold coated silicon substrates. This polymerization initiator molecule and a copper-based organometallic catalyst allowed tethered polyelectrolyte chains to be grown via radical polymerization at room temperature in aqueous solutions. To suppress consumption of the ATRP deactivator, a halide salt was added to the reaction mixture, which enabled controlled growth of the polyelectrolyte layers. Phase-modulated ellipsometry was used to follow the kinetics of layer growth and also to study the stretching and swelling behavior of the polyelectrolyte layers as a function of pH. It was found that the change in layer thickness of the diacid PIA brush was greater than that of the monoacid PMAA brush.; Combining inkjet printing and atom-transfer radical polymerization (ATRP) provides a facile and versatile method for producing patterned surfaces that may serve as platforms for a variety of applications. Through this dissertation, I also report the use of drop-on-demand technology to print chemically-graded interfacial layers or simple patterns that allow surface wetting characteristics to be tailored. (Abstract shortened by UMI.)... |
