Stereoselective Ring‐Opening Polymerization of Racemic Dithiolactones Assisted by Non‐Classical C─H⋯X Interactions

ABSTRACT Stereoselective polymerization offers a powerful route to the synthesis of high‐performance recyclable polymers, yet achieving rapid, controlled, and stereoselective chain growth remains challenging. Here, we introduce a catalytic system that is consistent with non‐classical C─H⋯X (X = O, S) hydrogen‐bonding interactions, in which a bulky quaternary ammonium cation creates a confined environment that orients both the monomer and the propagating chain end through weak yet directional interactions, thereby promoting highly stereoselective ring opening. This system enables ultrafast and stereoselective ring‐opening polymerization of chemically recyclable rac ‐dithiolactones in dichloromethane (DCM), yielding fully recyclable, stereoregular polythioesters ( P m up to 0.97, M n up to 225.6 kDa) that form stereocomplexes to boost the T m from 120.1°C to 224.1°C and deliver polyolefin‐like mechanical performance. More broadly, these results implicate non‐classical hydrogen‐bonding interactions in stereocontrol and offer a robust route to stereoregular, chemically recyclable polythioesters.