The increased popularity of reversible addition-fragmentation chain transfer (RAFT) polymerization over the past decade has been driven by high functional group tolerance, typically mild synthetic conditions, and excellent control. Provided the correct synthetic conditions are used, each polymer chain also has endgroups derived from the chain transfer agent (CTA) used, which can serve as a synthetic handle for further modifications, e.g., reduction of a trithiocarbonate or dithiobenzoate to yield a thiol. One current limitation with this is type of CTA-facilitated polymerization is the difficulty in synthesizing telechelic dithiol polymers that are even numbered (or odd numbered and asymmetric). Here, we focus on the use of a disulfide-containing RAFT CTA, bis(dodecylsulfanyl thiocarbonyl)disulfide (DDS), as a facile method to circumvent this limitation. Specifically, we investigate the control over molar mass for different synthetic conditions, varying the solvents and monomers used as well as the monomer:CTA and CTA:initiator ratios. We also study the polymerization kinetics in bulk monomer and in solution. We show that under optimized conditions it is possible to access polymers with good control over molar mass and low dispersity. Spectroscopic and spectrometric techniques are used to elucidate the endgroup structure, and polymers made using DDS are compared to analogous samples made using conventional RAFT-CTAs. Finally, we also demonstrate that it is possible to chain-extend in sequential polymerizations, suggesting good end group fidelity.

Trithiocarbonate disulfides as chain transfer agents

255th National Meeting (2018)

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