Date of Award
Doctor of Philosophy (PhD)
Douglas L. Gin
David M. Walba
Richard D. Noble
Polymerized ionic liquids (PILs) are a class of polyelectrolytes that contain an ionic liquid (IL) moiety in each monomer repeating unit that are connected through a polymeric backbone. Since ILs are small-molecule liquid materials with a unique combination of properties (e.g., negligible vapor pressure, high thermal stability, ion conductivity, high solubility for certain light gases, etc.), the development of ordered, phase-separated polymeric systems containing PIL segments has considerable implications with respect to a range of transport-dependent, energy-based technology applications. The work presented in this thesis was focused on the synthesis of two IL-based block copolymer (BCPs) platforms: (1) a new organic IL-based BCP platform (PIL-BCP) and its morphological phase behavior; and (2) the first example of metal-containing IL-based BCP (MCIL-BCP) platform that forms ordered microstructures in the neat state and has functional capabilities introduced by the incorporated metal complex.
The PIL-BCP platform was synthesized via sequential atom-transfer radical polymerization (ATRP) of styrene and styrenic imidazolium IL monomers with different side-chains on the imidazolium units (e.g., methyl, n-butyl, etc.). Small-angle X-ray scattering (SAXS) analysis of these BCPs showed the formation of four classic ordered morphologies of diblock copolymer (i.e., body-centered cubic spheres (SBCC), hexagonally packed cylinders (Hex), lamellae (Lam), and notably, bicontinuous gyroid (Gyr)), depending on both the volume fraction of the PIL block and the attached alkyl group on the imidazolium units.
The MCIL-BCP platform was synthesized by sequential reversible addition-fragmentation chain transfer (RAFT) polymerization of butyl methacrylate and a Co(II) bis(salicylate) anion-containing MCIL monomer. SAXS studies on MCIL-BCP samples made from these two monomers with 70 total repeat units but different block composition ratios showed the formation of ordered microstructures (i.e., S, Hex, Lam, and Gyr phases) in their neat states. This is the first example of an IL-based BCP that exhibits the Gyr phase in the neat state to our knowledge. Additionally, these MCIL-BCPs were found to have metal-induced properties such as reversible binding of small protic molecules and catalytic reactivities.
Shi, Zhangxing, "Synthesis of Ordered, Phase-Separated, Organic and Metal-Containing Ionic Liquid-Based Block Copolymers via Controlled Radical Polymerization" (2018). Chemistry & Biochemistry Graduate Theses & Dissertations. 291.