We report the synthesis and uses of a novel terpyridine-functionalized chain transfer agent (CTA) that produces well-controlled macromolecular architectures with terpyridine functionalities at one chain end via reversible addition-fragmentation chain transfer (RAFT) polymerization. The terpyridineterminated macromolecules with well-defined structures were further used for preparation of supramolecular diblock metallomacromolecules by bis(2,2′:6′,2′′-terpyridine)ruthenium(II) complex connectivity. The successful connectivity between two macromolecular blocks via the metallocomplex was confirmed by UV-vis, size exclusion chromatography (SEC), and differential scanning calorimetry (DSC) as well as atomic force microscopy (AFM) techniques.

A novel bipyridine-functionalized dithioester, 5,5′-bis(thiobenzoylthiomethyl)-2,2′-bipyridine (3), was first synthesized through a simple ester exchange reaction with the commercially available dithioester, carboxymethyl dithiobenzoate (CMDB), and further used as a RAFT agent in bulk polymerization of styrene for the synthesis of well-defined bipyridine-centered polystyrene polymers. The molecular weight is well-controlled, and also the molecular weight distribution remains quite narrow. This shows that the novel bipyridine-functionalized dithioester 3 is an efficient RAFT agent. More importantly, the good agreement between theoretical and 1 H NMR-determined molecular weights indirectly indicates that almost all of the polymer chains are centered by the bipyridine functional groups derived from the new RAFT agent. Two of the bipyridine-centered polystyrene polymers were further complexed with ruthenium(II) ions to produce tris(bipyridine)ruthenium(II)-centered polystyrene metallopolymers. The metallopolymers were characterized by UV-vis, fluorescence, size exclusion chromatography (SEC), and differential scanning calorimetry (DSC) techniques. The characterization data show that tris(bipypridine)ruthenium(II) ions have been successfully incorporated into the center of polymer chains.

The thermosensitive [60]fullerene end-capped poly(N-isopropylacrylamide) was successfully synthesized by the reaction of C(60) with dithiobenzoate-terminated poly(N-isopropylacrylamide), which was prepared by reversible addition-fragmentation chain-transfer (RAFT) polymerization in the presence of azobisisobutyronitrile (AIBN). Its structure was determined by FTIR, UV/Vis, and carbon and proton NMR spectroscopy as well as by size exclusion chromatography (SEC). The novel fullerenated polymer retained the thermosensitivity of poly(N-isopropylacrylamide). Moreover, it is soluble in water and most of the common organic solvents. Interestingly, it was able to form nanoparticle clusters in methanol and exhibited significant radical scavenging ability in cell viability and metabolic activity tests with fibroblasts and NOR-3 radicals.

Several polystyrene polymers were prepared by reversible addition-fragmentation chain-transfer (RAFT) polymerization of styrene, using two different RAFT agent-initiator systems, and then further characterized by NMR and SEC as well as MALDI-TOF-MS techniques. The data indicate that most of the polymer chains are terminated by the active groups (Ph-C(=S)-S-) derived from RAFT agents, and few of the polymer chains bear initiator fragments at one end. Most importantly, the structures arising from the intermediate RAFT radicals and their cross-termination adducts were detected. Also, the MALDI-TOF-MS analysis shows that the combination termination between two macromolecular radicals is minor, and the amount of dead chains is quite low. Thus, narrow molecular weight distribution is obtained. This analysis confirms the operation of the Rizzardo mechanism including the Monteiro intermediate radical termination model for the RAFT polymerization.

A new bipyridine‐functionalized dithioester was synthesized and further used as a RAFT agent in RAFT polymerization of styrene and N‐isopropylacrylamide. Kinetics analysis indicates that it is an efficient chain transfer agent for RAFT polymerization of the two monomers which produce polystyrene and poly(N‐isopropylacrylamide) polymers with predetermined molecular weights and low polydispersities in addition to the end functionality of bipyridine. The bipyridine end‐functionalized polymers were further used as macroligands for the preparation of star‐shaped metallopolymers. Hydrophobic polystyrene macroligand combined with hydrophiphilic poly(N‐isopropylacrylamide) was complexed with ruthenium ions to produce amphiphilic ruthenium‐cored star‐shaped metallopolymers. The structures of these synthesized metallopolymers were further elucidated by UV–vis, fluorescence, size exclusion chromatography (SEC), and differential scanning calorimetry (DSC) as well as NMR techniques. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4225–4239, 2007