Monomer-Recyclable Polyester from CO 2 and 1,3-Butadiene.

Synthesis of monomer-recyclable polyesters solely from CO 2 and bulk olefins holds great potentials in significantly reducing CO 2 emissions and addressing the issue of plastic pollutions. Due to the kinetic disadvantage of direct copolymerization of CO 2 and bulk olefins compared to homopolymerization of bulk olefins, considerable research attention has been devoted to synthesis of polyester via the ring-opening polymerization (ROP) of a six-membered disubstituted lactone intermediate, 1,2-ethylidene-6-vinyl-tetrahydro-2H-pyran-2-one (𝜹-L), obtained from telomerization of CO 2 and 1,3-butadiene. However, the conjugate olefin on the six-membered ring of 𝜹-L leads to serious Michael addition side reactions. Thus, selective ROP of 𝜹-L, which can precisely control the repeating unit for the production of polyesters potentially amenable to efficient monomer recycling, remains an unresolved challenge. Herein, we report the first example of selective ROP of 𝜹-L using a combination of organobase and N,N'-Bis[3,5-bis(trifluoromethyl)phenyl]urea as the catalytic system. Systematic modifications of the substituent of the urea shows that the presence of electron-deficient 3,5-bis(trifluoromethyl)-phenyl groups is the key to the extraordinary selectivity of ring opening over Michael addition. Efficient monomer recovery of oligo(𝜹-L) was also achieved under mild catalytic conditions. This article is protected by copyright. All rights reserved.