Polymers of Intrinsic Microporosity (PIMs) combine the desirable processability of polymers with a significant degree of microporosity generated from the inefficient packing of their rigid and contorted structures. They are attracting attention for a variety of applications including as membrane materials for gas separations. Over the last 30 years, membranes have become an established technology for separating gases and are likely to play key role in reducing the environmental impact and costs of many industrial processes such as O2 or N2 enrichment from air, natural gas upgrading and hydrogen recovery from ammonia production. This thesis describes the synthesis of a series of novel PIMs, primarily PIM-polyimide structures (PIM-PI) and investigates their potential in such applications. In particular, it focuses on the design and synthesis of solution processable PIMs in order to study how structural differences affect the gas permeability. The first section describes the synthesis of a variety of PIM-PIs using large bulky diamines derived from spirobisindane (SBI) and biphenylfluorene (BPF) structures which are useful monomers for achieving high BET (Brunauer-Emmett- Teller) surface areas (> 650 m2 g-1). The second section describes a whole series PIs based on novel and literature based Tröger’s base (TB) diamine monomers. Most of these exhibited good solubility, excellent thermal stability and intrinsic microporosity, with apparent BET surface areas in the range 450-739 m2 g-1. Notably, a polyimide derived from Me2TB and pyromellitic anhydride demonstrates gas permeability data above the 2008 upper bounds for important gas pairs such as O2/N2, H2/N2 and H2/CH4. The third section aims to enforce rigidity within the polymers further by incorporating differently substituted monomers based on rigid ethanoanthracene (EA) units. This includes the formation of a novel EA-EA based PI with an exceptionally rigid polymeric structure, possessing a BET surface area of 694 m2 g-1. In addition to very high permeability, this polymer demonstrates improved gas selectivity due to its enhanced performance as a molecular sieve, placing it amongst some of the highest performing polymers to date. The final section looks at other ways in which rigidity can be enforced including the formation of TB-polymers and thermally rearranged (TR) polymers and assesses their potential for future investigations.

Polymeric membranes typically possess a broad pore-size distribution that leads to much lower selectivity in molecular and ionic separation when compared to membranes made of crystalline porous materials; however, they are highly desirable because of their easy processability and low cost. Recently, a novel type of conjugated microporous polymers (CMPs) has shown uniform pore size and high porosity. However, their brittleness nature has prevented them from preparing robust membranes and using in pressure-driven membrane processes. In this dissertation, we demonstrate the fabrication of robust polycarbazole-type conjugated microporous polymer membranes using an easy to scale-up electropolymerization strategy. The mechanical properties of the CMP membranes were greatly enhanced based on membrane structure optimization and molecular design. The prepared membranes exhibited high uniform sub-nanometer pores and a precisely tunable membrane thickness and properties, yielding high molecular/ionic sieving performance. In addition, using the co-electropolymerization method, the CMP membranes achieve dual softness and functionalization adjustments. The membrane structure comprises rigid monomers to inherit the structural uniformity and flexible and charged monomers to enhance mechanical flexibility and improve ion selectivity by combining the precise size sieving and the Donnan effect. The dual-adjustments result in the further enhancement of the CMP membranes in ionic sieving performance. Inspired by light-gated ion channels in living cells, we further develop a smart artificial light-gated ion channel membrane. The prepared CMP membranes, based on a conjugated microporous polymer (CMP) functionalized with azobenzene and precisely designed on the molecular level, show uniform pore channels and highly sensitive light-switchable response. The photoisomerization results in reversible geometric changes in pore channel size, leading to “on-off-on” light-control over the channels, which results in light-gated ion transport across the smart membrane. The softness adjustment, functionalization adjustment to CMP membranes, and the design of smart CMP membranes provide potential applications for this important category of polymer materials in the membrane field.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19406号 / 工博第4122号 / 新制||工||1635(附属図書館) / 32431 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 中條 善樹, 教授 澤本 光男, 教授 赤木 和夫 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM