Synthesis and Post-Functionalization of Poly(conjugated ester)s Based on 3-Methylene-1,5-dioxepan-2-one

Abstract

Poly(α-methylene ester)s are an attractive type of functional aliphatic polyesters that represent a platform for the fabrication of various biodegradable and biomedical polymers. Herein, we report the controlled ring-opening polymerization (ROP) of a seven-membered α-methylene lactone (3-methylene-1,5-dioxepan-2-one, MDXO) that was synthesized based on the Baylis–Hillman reaction. The chemoselective ROP of MDXO was catalyzed by diphenyl phosphate (DPP) at 60 °C or stannous octoate (Sn(Oct)2) at 130 °C, generating α-methylene-containing polyester (PMDXO) with a linear structure and easily tunable molar mass. The ring-opening copolymerization of MDXO with ε-caprolactone or 1,5-dioxepan-2-one was also performed under the catalysis of DPP or Sn(Oct)2 to afford copolymers with different compositions and sequence structures that are influenced by the kinds of monomers and catalysts. PMDXO is a slowly crystallizable polymer with a glass transition temperature of ca. −33 °C, and its melting temperature and enthalpy are significantly influenced by the thermal history. The thermal properties of the copolymers are dependent on their composition and sequence structure. Finally, the post-modification of PMDXO based on the thiol-Michael addition reaction was briefly explored using triethylamine as a catalyst. Given the optimized condition, PMDXO could be dually modified to afford biodegradable polyesters with different functionalities.

Synthesis and antibacterial properties of fluorinated biodegradable cationic polyesters

“…Post-modification of PMDXO Poly(3-methylene-1,5-dioxepan-2-one) (PMDXO) was prepared by the ROP of MDXO following the published procedure. 58 PMDXO was end-acetylated to cap the terminal hydroxyl group that might accelerate plausible transesterification in the presence of a basic catalyst. This end-capped polymer was characterized by 1 H NMR and SEC, showing an M n,SEC of 6.6 kDa, a Ð of 1.03, and a DP (degree of polymerization) of 39 (Fig.…”

“…Recently, we reported a new class of poly(α-methylene ester)s that were synthesized by the controlled ring-opening polymerization (ROP) of 3-methylene-1,5-dioxepan-2-one (MDXO). 58 The obtained polymer (PMDXO) could be efficiently modified through the thiol-Michael addition reaction, affording biodegradable aliphatic polyesters with different pendent functionalities. Herein, we further modified PMDXO by the successive thiol-Michael addition reaction using the thiol compounds that contain quaternary ammonium motifs or alkyl/fluoroalkyl groups.…”

Chemoselective and controlled ring-opening copolymerization of biorenewable α-methylene-δ-valerolactone with ε-caprolactone toward functional copolyesters

“…Although it was reported that functional polyesters bearing pendent double bonds can be prepared by a polycondensation strategy without tedious protection and deprotection procedures, 23 the ROP of α-methylene lactones represents a more attractive strategy considering the potential advantages of good control over molecular weights, chain-end groups and macromolecular architectures. [24][25][26][27][28][29][30][31][32][33] For example, our group and others have successfully achieved the chemoselective ROP of the five-membered lactone α-methylene-γ-butyrolactone (MBL) or its copolymerization with ε-caprolactone (CL) and δ-valerolactone to exclusively produce functional (co)polyesters bearing pendent double bonds using organometallic catalysts or base/urea binary catalysts at low temperatures (typically at −40 °C). [26][27][28][29] Recently, Li and coworkers reported the controlled ROP of 3-methylene-1,5dioxepan-2-one (MDXO) to produce α-methylene-containing polyesters and their post-modification by the thiol-Michael addition reaction.…”

“…[26][27][28][29] Recently, Li and coworkers reported the controlled ROP of 3-methylene-1,5dioxepan-2-one (MDXO) to produce α-methylene-containing polyesters and their post-modification by the thiol-Michael addition reaction. 33 α-Methylene-δ-valerolactone (MVL) is a biorenewable sixmembered lactone bearing an exocyclic double bond, which can be easily synthesized by the reaction of δ-valerolactone with ethyl formate. Recently, we presented the chemoselective controlled ROP of MVL to produce a functional polyester with a closed-loop life cycle in the presence of a strong base/urea binary catalyst.…”

“…26–29 Recently, Li and coworkers reported the controlled ROP of 3-methylene-1,5-dioxepan-2-one (MDXO) to produce α-methylene-containing polyesters and their post-modification by the thiol-Michael addition reaction. 33…”