Synthesis of pyridine-based conjugated microporous polymers for CO₂ capture and conversion

Abstract

In this study, novel nitrogen-rich conjugated microporous polymers (CMPs) based on pyridine derivatives were synthesised and investigated for CO₂ capture and conversion applications. The CMPs were synthesised via Buchwald-Hartwig cross-coupling reaction, where ratios of monomers were varied to tune their properties. The synthesized polymers were characterised using X-Ray Diffractometry (XRD), UV-Vis-NIR spectroscopy, FT-IR spectroscopy, and scanning electron microscopy (SEM) methods. The total surface area of the materials were determined by the Brunauer–Emmett–Teller (BET) method, and the pore size distributions (PSD) determined by nonlocal density functional theory (NLDFT) method. Surface areas up to 75 m ²/g⁻¹ were found for these novel CMPs. To understand and find an optimal solvent for the synthesis to optimise the yield and surface area, solubilities of CMPs were evaluated by calculating the Hansen solubility parameters (HSPs). Determination of HSPs relies on the interaction between the solvent and polymer by the influence of three major intermolecular interactions; dispersion interaction (δD), hydrogen-bonding component (δH), and permanent dipole-dipole interaction (δP). This approach, the so-called Bristol-Xi’an Jiaotong (BXJ) approach, did not yield conclusive results in terms of tuning surface areas or PSDs. Finally, exploiting the presence of the well-known metal-binding motifs incorporated in the CMPs, metal-containing CMPs were also prepared. The effects on porosity and CO₂ uptake properties by direct cross-coupling with metal–organic co-monomers, and post-synthesis functionalized CMPs, treated with a metal, were investigated. The synthesised metal-containing CMPs showed a massive increase in the surface area of up to 229 m ²/g⁻¹, and CO₂ uptake of up to 5.7 wt%. The electrocatalytic CO₂ reduction and adsorption properties of the synthesised polymers were investigated, with initial results showing opportunities for CO₂ conversion using these novel functional CMP systems.

Date of Award	27 Sept 2022
Original language	English
Awarding Institution	University of Bristol
Sponsors	The Republic of Turkey Ministry of National Education
Supervisor	Charl F J Faul (Supervisor) & Paul G Pringle (Supervisor)