Biodegradable polymers via RAFT

• Main Author: Suwattana, Siripan
• Published: University of Leeds 2011
• Subjects: 541.2254
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.549765

This research has shown that biodegradable monomer (5,6-benzo-2- methylene-1,3-dioxepane) (BMOO) can be achieved. Also its homo-and-eo- polymerisation can be successfully realised via RAFT and ROP polymerisation techniques. BMOO was synthesised with the modification via the dehydrobrornination of 5,6-benzo-2-(bromomethyl)-1,3-dioxepane in a good yield (95% yields). The homopolymerisation of BMOO were designed to produce a target OP of 200 via living "polymerisation" and complete ring-opening polymerisation. A narrow POI (1.09) and an M n= 4,697 g mol' were observed after 24 hours for the reaction in the presence of the CT A(MCPDB)' The copolymerisation of MMA and BMOO in the presence of the CT A(CPDB) gave better control over the polymerisation than that achieved using the CT A(MCPDB) and the CTA(ETSPE), at 120 "C. A narrow POI (1.36) and an Mn= 16,662 g mol' were observed after 24 hours. The copolymer was shown to be results of a combination of 1,2-addition polymerisation and of ring-opening copolymerisation. The reactivity ratio of the monomers was calculated using the Kelen- Tudos method (rMMA= 1.12 and rBMDO= 0.43). The copolymerisation of styrene with BMOO in the presence of the CTA(cPDB) gave the better control than that given by the CT A(MCPDB) and the CTA(ETSPE), at 120aC (Sty:BMOO, with an initial feed of 33%:67%). A narrow POI (1.18) and M n= 9,684 g rnol' were obtained after 24 hours. The % ratio of BMOO that was incorporated into the final polymeric chain was Sty:BMOO= 64.3%:35.7% and the copolymer was formed from ring-opening polymerisation only. The reactivity ratio of the monomers was calculated using the Kelen-TOdos method (rsty= 2',56 and rBMDO= 0.64). NMR, FTIR and UVlVis spectroscopy provided further evidence that the final polymers were the product of a ring-opening polymerisation. As required, thermal analysis techniques were used to ascertain the consequences of the copolymerisation, with respect to thermal consequences (decomposition) and compositional features.