Trithiocarbonate RAFT agents

Table 9.16 Non-Symmetrical Trithiocarbonate RAFT Agents RAFT Agent Monomers" RAFT Agent Monomers" RAFT Agent Monomers"...

RAFT in miniemulsion has also been reported" and is more readily used to produce polymers with a narrow molecular weight distribution. Moad et used RAFT in miniemulsion to provide narrow dispersity PS in a batch process. Significant retardation w as observed with the dithiobenzoate RAFT agent used. However, this is markedly reduced when aliphatic dithioesters "" or trithiocarbonate RAFT agents are used. " One of the issues with traditional miniemulsion polymerization is the high level of surfactant and co-stabilizer that is typically employed. Pham et have recently described surfactant-free... 

Another attempt to incorporate PNIPAM segments into the ABA architecture has been completed through the RAFT mechanism. PDMA-PNIPAM-PDMA copolymers were synthesized at room temperature in water using a novel water-soluble trithiocarbonate RAFT agent. Thermo sensitive reversible micelles are obtained at temperatures above the LCST of PNIPAM by hydrophobic association showing that these triblocks are promising candidates for drug delivery applications. 

The formation of BA-St block copolymers has been successfully carried out in miniemulsion mediated by trithiocarbonate RAFT agents. The choice of surfactant and block sequence is important for reducing the influence of terminated chains on the distribution of the polymer obtained. Poly(acrylate)s as well as poly (methacrylate) s were successfully synthesized via RAFT polymerizations using 2-cyano-2-butyl dithiobenzoate (CBDB) as RAFT agent. ... 

The utility of trithiocarbonate RAFT agents was disclosed in the first RAFT patent and many papers now describe their applica-... 

Unsymmetrical primary and secondary trithiocarbonate RAFT agents are readily synthesized from a thiolate anion, carbon disulfide and an alkyl halide. 

RAFT agents have been compared for their ability to control MMA polymerization. Tertiary cyanoalkyl trithiocarbonates provide very good control over molecular weight and distribution and there is little retardation. The secondary trithiocarbonate RAFT agent with R=-CHPh(CN) also provides good control but a prolonged inhibition period attributed to slow reinitiation is manifest. The trithiocarbonate... 

Two methods offering simultaneous control over both molecular weight and polymer chain stereochemistry are reported. RAFT polymerization of MMA with trithiocarbonate RAFT agents and added scandium triflate provides a more... 

Show schematically how nonsymmetrical trithiocarbonate RAFT agents can be synthesized by a one-pot procedure. 

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