Alex Lubnin - Waterborne RAFT polymers

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  Publication Details (including relevant citation   information):

  European Polymer Journal, v. 46(7), pp. 1563-1575 (2010)


  A   recently invented novel family of RAFT (Reversible  Addition-Fragmentation   chain Transfer)  agents having a   common formula Z–C(@S)–S–CR2COOR1  where Z = –SR,   –NR2,   or –OR, and R1  represents H or a   variety of functional groups allows for tailoring their   hydrophilicity–hydrophobicity   balance. A limited hydrophilicity of the RAFT agents can be   achieved which is sufficient for their diffusion through water,   yet the agents are hydrophobic enough to phase-separate out of   water. Thus, the limited hydrophilicity of otherwise hydrophobic   agents allows them to be at the loci of polymerization making   them suitable for the emulsion polymerization mechanism. With   several RAFT agents, good control over molecular weight was   demonstrated for a broad variety of ab   initio acrylic emulsion   polymers. For methyl   methacrylate, a portion of RAFT did not engage, resulting in less   than the theoretical number of polymer chains. It was found,   however, that as little as 10 wt% of an acrylic monomer slowed   down polymerization enough to engage all RAFT agent molecules and   yield predicted molecular weights. A broad variety of colorless   and odorless telechelic acrylic and methacrylic emulsion polymers   were synthesized. Microemulsion and solution-dispersion   techniques produced clean colloidally stable RAFT dispersions.   These two techniques did not require RAFT agents with tailored   hydrophilicity–hydrophobicity. The UV spectra and photooxidative   stability of the RAFT polymers were studied. The RAFT fragment in   polymers appeared to have no impact on their photooxidative   stability.



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