Designing Microporous Polymers for Separations

Abstract

In Chapter 1, we investigate the influence of side-chain length and dispersity in ring-opening metathesis polymerization (ROMP) polymers with pore-generating side chains. Macromonomers with four discrete monodispersities are separated and polymerized to produce bottlebrush polymers with monodisperse side chains. Each bottlebrush polymer is fabricated into a free-standing film. Pure-gas experiments are performed to explore the impact of dispersity and side chain length on gas separation performance.

In Chapter 2, we evaluate the mixed-gas performance of a class of bottlebrush polymers described in Chapter 1. Gas sorption, diffusion, and CO₂-induced plasticization are reported. Competitive sorption effects are studied using 50:50 mixture of CO₂/CH₄. Separation performance at different compositions of CO₂/CH₄ is also explored.

In Chapter 3, we incorporate nitrile functionality into the structure of a family of polymers with rigid, porogenic side chains described in Chapters 1 and 2. Statistical and block copolymers are synthesized to demonstrate the role of grafting density on separation performance and CO₂ plasticization resistance. Sorption experiments are performed to determine improvements to selectivity.

In Chapter 4, we describe the optimized SN Ar synthesis of a poly(arylene ether) (PAE) that produces high molecular weight polymers. The synthesis of an analogous PAE with C-H functionality instead of C-F is also reported. Porosity and free volume are investigated in both PAEs. Separation performance is characterized and compared to other polymers with similar structural motifs.