Sorption of Gases and Liquids by Polymers of Intrinsic Microporosity (PIMs)

Abstract

This study presents the synthesis of polymers of intrinsic microporosity and theinvestigation of their microporosity using gas sorption and adsorption of liquidsand vapours.Microporous polymeric materials PIM-1, TAPIM-1, PIM-2 and PIM-7 weresynthesised using step-growth polymerisation. The microporosity of thesematerials was studied using gas sorption and adsorption of molecules in the liquidphase.A procedure to validate gas sorption methods was undertaken before being usedto characterise microporous materials. The sorption methodology was validatedusing standard reference materials (SRMs) and collaborative testing, and the PSDevaluation was validated using a well defined crystalline material.Different approaches to obtaining pore size distribution (PSD) data were dealtwith. Gas sorption methods that use CO2 at 273 K and at 303 K, N2 at 77 K, H2 at77 K, and Xe (298 K) to determine PSD were compared. The Horvath-Kawazoe(HK) model was presented as the preferred model and the N2, CO2 and H2sorption data were treated under this approach. CO2 PSD data at 273 K and at303 K was compared against N2 PSD data and a novel complementaryrelationship established. PIM-1 samples in film form and powder form were usedto investigate the effect of sample form on the sorption properties of the material.PIM-1, PIM-2, TAPIM-1, ethano-anthracene PIM-1 copolymers, and triptycenebased PIMs were used to investigate the influence of polymer structure on gassorption properties.The free volume properties of a PIM-1 ethano-anthracene copolymer (PIM-CO1-40), was compared against PIM-1. A number of independent techniques, namelyN2 sorption, Xe sorption, Positron annihilation lifetime spectroscopy (PALS), and129Xe NMR were used to probe the free volume. The time dependence of freevolume and its bearing on diffusivity of PIM-1 membranes was investigated.Water, chloroform and simple alcohols were used to investigate adsorption in theliquid and vapour phases. Interaction with PIM-1 the aromatic ether linkage andthe nitrile group produced frequency shifts in ATR-FT-IR spectra. These frequencyshifts were used to compare relative strengths of the hydrogen bonds.

Date of Award	1 Aug 2011
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Peter Budd (Supervisor)