Synthesis Of Polymers Bearing Functional End-Groups By RAFT Polymerization And Investigation Of Their Properties

Three novel RAFT agents bearing functional groups, 4-diphenylamino-dithiobenzoic acid benzyl ester (DDABE), S, S'-bis (1-naphthylmethyl) trithiocarbonate (BNTTC), S, S'-bis (9-anthrylmethyl) trithiocarbonate (BATTC) were synthesized and successfully used in the RAFT polymerization of vinyl monomers. The results were shown as follows.(1) A novel RAFT reagent bearing triphenylamine (TPA) group, 4-diphenylamino-dithiobenzoic acid benzyl ester (DDABE) was synthesized and successfully used to the reversible addition-fragmentation chain transfer (RAFT) polymerizations of styrene (St) and methyl acrylate (MA) to prepare end-functionalized polymers. The polymerization results showed that the RAFT polymerizations of St and MA could be well controlled using DDABE as the RAFT agent. Number-average molecular weight (Mn, GPC) increased linearly with monomer conversion, and molecular weight distributions were relatively narrow (PDI < 1.50). The successful reaction of chain extension and analysis of 1H NMR spectra confirmed the existence of the functional TPA group at the most of the chain-end of polymers. The effect of molar ratio among St/DDABE/AIBN on polymerization was investigated. In addition, the UV and fluorescence properties of triphenylamine-terminated polymers were studied.(2) A novel reversible addition-fragmentation chain transfer reagent bearing naphthalene group, S, S'-bis (1-naphthylmethyl) trithiocarbonate (BNTTC), was synthesized and used to the RAFT polymerizations of St. The polymerization results showed that both the AIBN-initiated and thermal-initiated RAFT polymerizations of St could be well controlled using BNTTC as the RAFT agent. Number-average molecular weight (Mn, GPC) increased linearly with monomer conversion and were close to the theoretical values, and molecular weight distributions were relatively narrow (PDI < 1.50). The successful reaction of chain extension and analysis of 1H NMR spectrum confirmed the existence of the functional group at the chain-end of PS. The influence of molar ratio between St/BNTTC on polymerization was investigated. Then well-defined naphthalene end-capped poly(styrene)-block-poly(N-isopropyl-acrylamide)-block-poly(styrene) (PS-b- PNIPAM-b-PS) amphiphilic triblock copolymers with different molecular weights and block copolymer compositions were successfully prepared via RAFT polymerizations using the obtained PS as macro-RAFT agent. The aggregation behaviour of the prepared PS-b-PNIPAM-b-PS in water/DMF mixture was studied by transmission electron microscopy (TEM). The effect of the copolymer concentration, PNIPAM block length and the irradiation of UV-light on the sizes and morphologies of micelles were also investigated.(3) A novel reversible addition-fragmentation chain transfer reagent bearing anthracene group, S, S'-bis (9-anthrylmethyl) trithiocarbonate (BATTC), was synthesized and used to the RAFT polymerizations of St. The polymerization results showed that both the AIBN-initiated and thermal-initiated RAFT polymerizations of St could be well controlled using BATTC as the RAFT agent. Number-average molecular weight (Mn, GPC) increased linearly with monomer conversion and were close to the theoretical values, and molecular weight distributions were relatively narrow (PDI < 1.50). The successful reaction of chain extension and analysis of 1H NMR spectrum confirmed the existence of the functional group at the chain-end of PS. Optical properties of the obtained PS were characterized by fluorescence and UV absorption. Photochemical properties of the obtained PS were described under irradiation of UV light.