H-Bonding Organocatalysts for the Living, Solvent-Free Ring-Opening Polymerization of Lactones: Toward an All-Lactones, All-Conditions Approach
Date of Original Version
The developing urea class of H-bond donors facilitates the solvent-free ROP of lactones at ambient and elevated temperatures, displaying enhanced rates and control versus other known organocatalysts for ROP under solvent-free conditions. The ROPs retain the characteristics of living polymerizations despite solidifying prior to full conversion, and copolymers can be accessed in a variety of architectures. One-pot block copolymerizations of lactide and valerolactone, which had previously been inaccessible in solution phase organocatalytic ROP, can be achieved under these reaction conditions, and one-pot triblock copolymers are also synthesized. For the ROP of lactide, however, thioureas remain the more effective H-bond donating class. For all (thio)urea catalysts under solvent-free conditions and in solution, the more active catalysts are generally more controlled. A rationale for these observations is proposed. The triclocarban (TCC) plus base systems are particularly attractive in the context of solvent-free ROP due to their commercial availability which could facilitate the adoption of these catalysts.
Pothupitiya, Jinal U., Nayanthara U. Dharmaratne, Terra Marie M. Jouaneh, Kurt V. Fastnacht, Danielle N. Coderre, and Matthew K. Kiesewetter. "H-Bonding Organocatalysts for the Living, Solvent-Free Ring-Opening Polymerization of Lactones: Toward an All-Lactones, All-Conditions Approach." Macromolecules 50, 22 (2017): 8948-8954. doi:10.1021/acs.macromol.7b01991.