Synthesis of poly(conjugated ester)s by ring-opening polymerization of cyclic hemiacetal ester bearing acryl skeleton

• Published in: European polymer journal 2019-11, Vol.120, p.109185, Article 109185
• Main Authors: Kohsaka, Yasuhiro, Yamashita, Mai, Matsuhashi, Yosuke, Yamashita, Shuji
• Format: Article
• Language: English
• Subjects: Acetaldehyde; Butyrolactone; Chain scission; Chemoselective main chain scission; Conjugate substitution; Copolymerization; Copolymers; Cyclic hemiacetal ester; Methylene; Molecular weight; Poly(conjugated ester); Polyester resins; Polyesters; Polymerization; Polymers; Ring opening polymerization; Studies; Substitution reactions; Tin; α-exomethylene lactone
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/j.eurpolymj.2019.08.012

[Display omitted] •Ring-opening polymerization of a cyclic hemiacetal ester with an acrylate skeleton.•Poly(conjugated ester) formed via the elimination of acetaldehyde from the monomer.•The potential of cyclic hemiacetal ester as an alternative to four-membered lactone.•Chemoselective degradation of the copolymer at the conjugated ester. Ring-opening polymerization (ROP) of 2,6-dimethyl-5-methylene-1,3-dioxan-4-one (DMDO), a cyclic hemiacetal ester containing an acrylate skeleton, was investigated. Although the ROPs catalyzed by tin(II) 2-ethylhexanoate [Sn(Oct)2] and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) did not yield polymeric products, diphenyl phosphate (DPP) functioned a catalyst for the ROP through acyl scission accompanying with the elimination of acetaldehyde at 50 °C and 80 °C. The resulting polymer was a poly(conjugated ester) that had similar structure to the polymer of α-methylene-β-butyrolactone (MβBL), an α-exomethylene lactone with four-membered ring. Copolymerizations of ε-caprolactone and δ-valerolactone were also performed to yield the corresponding polyesters. The chemoselective main chain scission of the copolymers at the conjugated ester units were achieved by conjugate substitution reaction with benzyl mercaptan. Although the ROP of DMDO left a problem in the control of molecular weight, DMDO exhibited a potential as an easier accessible monomer alternative to MβBL for the preparation of bio- and chemo-degradable polyesters.