Synthesis of Novel Water Soluble Conjugated Polymers Based on Poly-Phenylene Vinylene and Poly-Phenylene Ethynylene

Abstract

This thesis focuses on the synthesis using atom transfer radical polymerisation ATRP, and the photophysical characterisation of novel grafted PPV and PPE derivatives with various solubilities. Initially a series of functionalised monomers 2.4, 2.5, 2.10 and 2.11 were successfully synthesised from hydroquinone 2.7. Heck and Sonogashira polymerisation methods were then used on these monomers to give hydroxyl functionalised polymers PPVOH 2.2 and PPEOH 2.3. Then, bromoester functionalised PPV and PPE were prepared through the post polymerisation esterification using α-bromoisobutyryl bromide 2.35 which successfully gave PPVMI 3.1 but a poor yield of PPEMI 3.2.1. Using a bromoester functionalised monomer 2.11 and the use of the Sonogashira polymerisation, directly synthesised PPEMI 3.2.2 was achieved in higher yield than post polymerisation esterification. Functionalisation of these macroinitiators PPV 3.1 and PPE 3.2.2 using ARGET ATRP was found to be successful and allow the synthesis of both PPV and PPE grafted PnBA polymers both of, which have enhanced photoluminescence properties. Further synthesis of cationic grafted PPV and PPE using 2-trimethylaminoethylmethacrylate (TMAEMA) was successful again using ARGET ATRP. Both low and high molecular weight PPV-g-PTMAEMA (5.7 and 5.8) and PPE-g-PTMAEMA (5.9 and 5.10) were able to be prepared. The grafting polymerisation of anionic sulfopropyl acrylate (SPA) was also achieved using phase transfer complexation, using 18-crown-6, and then ARGET ATRP was again implemented for the synthesis of low and high molecular weight anionic grafted polymers PPV-g-PSPA (6.2 and 6.3) and PPE-g-PSPA (6.4 and 6.5). The antibacterial activities of the nongrafted and grafted polymers were tested against wide spectrum of bacteria, which indicated activity for all of the cationic grafted polymers with the best activity for the high molecular weight PPE derivative 5.10. Anion sensing was also explored using the more soluble low molecular weight cationic PPV 5.7 and it showed its sensing capability with enhanced selectivity towards iodide ions.