Branched polymers have received considerable interest over recent decades due to their unique properties including complex architectures, low viscosities, good solubility, and high numbers of potentially diverse terminal functional groups. [1][2][3] The preparation of branched polymers by conventional free radical polymerization (FRP) of mixtures of mono-vinyl and multi-vinyl monomers is somewhat limited due to the onset of gelation following excessive crosslinking, which may readily occur at low monomer conversion. 4 Nonetheless, a number of branched polymer architectures have been reported using various strategies including the chain transfer monomer approach, 5-8 homopolymerization of multi-functional monomers; 9-12 gelation is prevented in the latter case through excessive dilution, employing solvents exhibiting high transfer constants or by utilizing excessive amounts of initiator at high temperature. Another approach, commonly referred to as the Strathclyde methodology, involves the copolymerization of mono-and bi-functional monomers in the presence of a chain transfer agent (CTA). [13][14][15] The resulting branched polymers contain a large number of conjoined primary chains that are chemically near-identical to linear polymers generated in the absence of the bi-functional monomer; consequently, the statistical nature of the branching generates broad molecular weight distributions and a range of species with varying numbers of chain-ends. The Strathclyde methodology has received significant attention in the literature with the majority of publications relying on the use of thiol-based CTAs. [16][17][18][19][20] Whilst thiols have been extensively studied as CTAs in the FRP of a wide range of monomers, they have considerable malodor, may exhibit acute toxicity and readily undergo oxidation under atmospheric conditions, 21 which generates handling problems during industrial scale processing. 22 The synthesis of thiolbased CTAs containing bespoke structures remains a difficult task and as a result the range of CTA structures studied is generally heavily dependent on commercial availability thiols, thereby limiting the diversity of research scope. Routes that allow ready synthesis of a diverse range of thiols, or synthetic equivalents of thiols, for use in FRP would offer access to new chain end functionality via readily scale-able syntheses.Dithiocarbonates (xanthates) offer an efficient protecting group chemistry for thiols, they can be synthesized without difficulty and readily undergo deprotection in the presence of primary amines under ambient conditions. 23 We have recently reported the use of xanthates as thiol protecting groups for the synthesis and surface group modification of low generation thiol-functional dendrimers, linear-dendritic hybrids, and hyper-branched polydendrons, using a one-pot deprotection/ functionalization strategy. [24][25][26] Thiocarbonyl containing compounds, including xanthates, dithiobenzoates, dithiocarbamates and trithiocarbonates, are commonly used to provide control with...