The Use of Polymeric Systems to Control Microenvironment and Moderate Anion Binding Affinities

This research has examined a variety of macromolecules; including hyperbranched polymers, di- block copolymers and tri-block copolymers. The architecture of these materials has been exploited for anion binding and transportation applications. The first area of study focussed on the interior properties of hyperbranched polymers. This work looked at controlling the environment surrounding a receptor and anion binding was the tool used to probe these properties. Hyperbranched poly 3,5 diacetoxybenzoic acid of varying molecular weights was used to house an anion receptor and the effect upon binding affinities of a variety of anions was measured. The polymer had a positive effect upon binding and transporting the 4-nitrophenolate anion from one aqueous layer to another through organic media. However, a different observation was made for the polymeric receptors than the free receptor. For the small and medium sized polymers (3,000 and 6,000 Mw respectively), the binding was higher than the free receptor only, although, binding dropped significantly for the highest molecular weight studied (14,000 Mw). For a water-soluble anion receptor system a different approach was employed. This consisted of a biocompatible di- block copolymer micelle composed of poly (ethylene glycol) and poly (ɛ-caprolactone) (mPEG-b- PCLn). The free receptor and medium hyperbranched polymer (6,000 Mw) was encapsulated within micelles. Encapsulation and stability of complexes was verified by UV/Vis spectroscopy. The next area studied continued the theme of encapsulation using di-block polymers. This work involved tethering mPEG with a receptor and co-micellized with di-block copolymers, where the co-micellization properties of complexes were probed using fluorescence spectroscopy. The final area involved covalently incorporate binding sites as co-monomers during controlled synthesis of amphiphilic terpolymers using atom transfer radical polymerisation (ATRP). This polymer would consist of a PEG block and a second block containing both the copolymer of methyl methacrylate and an anion receptor. For binding characterisation, displacement approach was conducted using Uiv-Vis measurements.