Date of Award

Spring 1-1-2013

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry & Biochemistry

First Advisor

Douglas L. Gin

Second Advisor

Richard D. Noble

Third Advisor

Daniel L. Feldheim

Fourth Advisor

Mark P. Stoykovich

Fifth Advisor

Wei Zhang

Abstract

CO2 capture process development is an economically and environmentally important challenge, as concerns over greenhouse gas emissions continue to receive worldwide attention. Many applications require the separation of CO2 from other light gases such as N2, CH4, and H2 and a number of technologies have been developed to perform such separations. While current membrane technology offers an economical, easy to operate and scale-up solution, polymeric membranes cannot withstand high temperatures and aggressive chemical environments, and they often exhibit an unfavorable tradeoff between permeability and selectivity. Room-temperature ionic-liquids (RTILs) are very attractive as next-generation CO2-selective separation media and their development into polymerized membranes combat these challenges. Furthermore, polymers that can self-assemble into nanostructured, phase-separated morphologies (e.g., block copolymers, BCPs) have a direct effect on gas transport as materials morphology can influence molecular diffusion and membrane transport performance.

In this thesis, nanophase-separated, RTIL-based AB and ABC di- and tri-BCPs were prepared via the sequential, living ring-opening metathesis polymerization (ROMP) of an ILbased monomer and one or more mutually immiscible co-monomers. This novel type of ion-containing BCP system forms various ordered nanostructures in the melt state via primary and secondary structure control. Monomer design and control of block composition, sequence, and overall polymer lengths were found to directly affect the ordered polymer assembly. Supported, composite membranes of these new BCPs were successfully fabricated, and the effect of BCP composition and nanostructure on CO2/light gas transport properties was studied. These nanostructured IL-based BCPs represent innovative polymer architectures and show great potential CO2/light gas membrane separation applications.

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