Syndioselective ring-opening polymerization and copolymerization of trans-1,4-cyclohexadiene carbonate mediated by achiral metal- and organo-catalysts

The ring-opening polymerization (ROP) of trans -1,4-cyclohexadiene carbonate (CHDC) has been investigated computationally and experimentally. DFT computations indicate that ring-opening of CHDC is thermodynamically possible, yet to a lesser extent than that of trans -cyclohexene carbonate (CHC). Effective homopolymerizations of rac -CHDC and simultaneous or sequential copolymerizations of rac -CHDC with rac -CHC and l -LA were achieved with a diaminophenolate zinc-based complex ([(NNO)ZnEt]) or a guanidine (TBD) associated with an alcohol. These ROP reactions, which confirmed the lower reactivity of rac -CHDC vs. rac -CHC, especially in homopolymerization, proceeded without any decarboxylation. Quite uniquely, highly syndiotactic PCHDC was obtained from ROP of rac -CHDC with both the zinc- and TBD-based catalysts, as revealed by 13 C{ 1 H} NMR studies. The prepared homopolymers and block or random copolymers were characterized by 1 H, 13 C{ 1 H} NMR, MALDI-ToF MS, SEC and DSC techniques.