Crosslinked polymer networks that are largely insoluble and tolerant to various chemical environments are useful in solid-supported chemistries and as sorbents in chemical separation. The selective retention of organic pollutants is an area of environmental importance for the clean-up of contaminated water sources, and a family of ion-exchange hypercrosslinked polymer particles have recently been developed for use as mixed-mode solid phase extraction sorbents. Expanding this family of polymers will give rise to a greater range of materials with enhanced selectivity and capacity for specific analytes of environmental concern. This work is an investigation of methods to synthesise and functionalise crosslinked polymer networks with ion-exchange character.The approaches explored for the synthesis of crosslinked polymers containing aromatic rings bridged by methylene (–CH2) chains include phenol-formaldehyde inspired chemistry, precipitation polymerisation, and Friedel Crafts chemistry. Weak anion-exchange character was imparted by the introduction of tertiary amine groups through post-polymerisation chemical modification reactions. Furthermore, by utilising amino acid derived alkyl esters it was proposed that there could be potential to exploit the weak cation-exchange character of the deprotected carboxylic acid and harness and exploit zwitterionic character.The use of precipitation polymerisation to synthesise poly(divinylbenzene-co-vinylbenzyl chloride) yielded spherical particles of low polydispersity in the 2-5 μm size range, with tuneable particle size and porosity (0-740 m2/g). Subsequent hypercrosslinking using Friedel-Crafts chemistry produced microporous polymers with a high concentration of micropores and ultra-high specific surface areas (1,900 m2/g). Amino acid derived esters, including sarcosine methyl and ethyl esters, and the L- and D- enantiomers of phenylalanine methyl ester, were utilised in a post-polymerisation amination study to impart weak anion-exchange character into the polymers at a level of around 1 mmol/g.Through evaluation of the macroreticular and hypercrosslinked variants as mixed-mode solid phase-extraction sorbents for the extraction of spiked organic analytes from ultra-pure water, it was found that these sorbents possess additional and useful functionality that is distinct from the weak anion-exchange polymeric sorbents that have been reported previously.
|Date of Award||27 Jan 2017|
- University Of Strathclyde
|Sponsors||EPSRC (Engineering and Physical Sciences Research Council) & University of Strathclyde|
|Supervisor||Peter Cormack (Supervisor) & David Sherrington (Supervisor)|