2‐Cyanopropan‐2‐yl versus 1‐Cyanocyclohex‐1‐yl Leaving Group: Comparing Reactivities of Symmetrical Trithiocarbonates in RAFT Polymerization

This study introduces bis(1‐cyanocyclohex‐1‐yl)trithiocarbonate (TTC‐bCCH) as a novel trithiocarbonate chain transfer agent and compares its reactivity with the previously described bis(2‐cyanopropan‐2‐yl)trithiocarbonate (TTC‐bCP) for the reversible addition‐fragmentation chain transfer (RAFT) polymerization of styrene (St), n‐butyl acrylate (nBA), and methyl methacrylate (MMA). Significant findings include the effective control of Mn and low dispersities from the onset of polymerization of St and nBA showing swift addition‐fragmentation kinetics, leading to similar behaviors between the two RAFT agents. In contrast, a fourfold decrease of the chain transfer constant to MMA is established for TTC‐bCCH over TTC‐bCP. This trend is confirmed through density functional theory (DFT) calculations. Finally, the study compares thermoplastic elastomer properties of all‐(meth)acrylic ABA block copolymers produced with both RAFT agents. The impact of dispersity of PMMA blocks on thermomechanical properties evaluated via rheological analysis reveals a more pronounced temperature dependence of the storage modulus (G′) for the triblock copolymer synthesized with TTC‐bCCH, indicating potential alteration of the phase separation. Bis(1‐cyanocyclohex‐1‐yl)trithiocarbonate (TTC‐bCCH) is introduced as a novel RAFT agent, comparing its efficacy in polymerizing styrene, n‐butyl acrylate, and methyl methacrylate with that of bis(2‐cyanopropan‐2‐yl)trithiocarbonate (TTC‐bCP). Kinetic studies and DFT calculations reveal notable differences in leaving group abilities for the two RAFT agents in MMA polymerization. This study helps to better rationalize the design of RAFT agents for synthesizing well‐defined all‐(meth)acrylate ABA‐type block copolymers with thermoplastic elastomer properties.