Synthetic Studies on Polymers of Intrinsic Microporosity for Gas Separation Membrane Material

Abstract

Membrane gas separation has been employed in a range of industrial processes for theseparation of almost all commercially important gas pairs, featured by energy efficiency,cost-effectiveness and environmental friendliness. Current commercial membrane materialsgenerally focus on polymerics. Since the seminal publication on polymers of intrinsicmicroporosity (PIMs) by Budd and McKeown in 2004, considerable attention from both theacademic and industrial communities has been drawn to these unique polymers. In this thesis,PIMs are therefore studied mainly via synthetic chemistry.The first part of the thesis (Chapters 3-5) describes three works relating to the syntheticmethods of PIMs. Chapter 3 introduces a novel AB-route polymerisation for high-molecularPIMs, a dibenzodioxin-forming polycondensation, in order to overcome the stringentstoichiometric balance which is necessarily obeyed in the regular AA+BB polycondensationroute. Chapter 4 focuses on the synthesis of alternating copolymers of PIMs by use of anABA monomer, enlightened by the synthetic study of the AB-type monomer in Chapter 3. Aperfectly alternating copolymer and its corresponding statistical copolymer are prepared andinvestigated by comparing their physicochemical properties, in particular the gas permeationperformance. In Chapter 5, a fluoride-mediated polycondensation is developed as analternative method of PIM synthesis. In this method, t-butyl dimethyl silyl (TBS)-protectedbiscatechol acts as a potential nucleophile to react with a common tetrafluoro monomer, withthe aid of fluoride ion. The polymerisation conditions are optimised to give high-molecularweight film-forming PIMs.The second part (Chapters 6 and 7) aims to explore new structures for the fabrication ofPIMs possessing enhanced gas separation performance. In Chapter 6, on the basis of currentPIM design concepts, a novel PIM with significant improvement in rigidity along thepolymer backbone is successfully synthesised. According to the preliminary gas separationtests, this polymer displays exceptional performance compared to other PIMs and showspotential commercial applications. Chapter 7 presents the synthesis of a series offunctionalised PIM homo-polymers and copolymers, such as methoxy-containing andhydroxyl-containing polymers. In addition, attempts to prepare functionalised