Fluorinated ɛ-caprolactone: Synthesis and ring-opening polymerization of new α-fluoro-ɛ-caprolactone monomer

Fluorinated polyester was synthesized from a novel α-fluoro-ɛ-caprolactone monomer (α-FCL). The monomer was synthesized from commercially available cyclohexene oxide in three steps. Baeyer-Villiger reaction using 3-chloroperoxybenzoic acid of the corresponding 2-fluorocyclohexanone resulted in formation of two isomeric lactones α-and-ɛ-fluoro-ɛ-caprolactones in 1:1.2 molar ratio, respectively. Poly(α-fluoro-ɛ-caprolactone) was synthesized by bulk ring-opening polymerization of α-fluoro-ɛ-caprolactone monomer (α-FCL) catalyzed by stannous octanoate, Sn(Oct)2 at 120 °C for 6 h. Relationships between reaction time, polymer yield, and molecular weight were established. The ring-opening polymerization of ɛ-fluoro-ɛ-caprolactone (ɛ-FCL) produce geminal fluorohydrin, which is not stable and it is subsequently dehydrofluorinated to give the corresponding aldehyde. Copolymerization of α-FCL with ɛ-caprolactone (ɛ-CL) in various feed ratios was also investigated. Detail microstructure analyses of the copolymers were accomplished from 1H, 13C and 2-D NMR data. Presence of fluorine atoms is expected to regulate the chemical and physical properties of the polyester.

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