Polymerization of poly(ε-caprolactone) using yttrium triflate

Abstract

The ring-opening polymerization of ε-caprolactone (CL) has been initiated by yttrium triflate (trifluoromethanesulfonate) in air using simple glass vials at 60°C without desiccation steps and stirring. The number averaged molecular weight and molecular weight distribution of the obtained poly(ε-caprolactone) (PCL) was 5000-12000 and about 1.2, respectively. It was found that this polymerization reaction of CL was activated by the addition such as little water or 2-propanol. The copolymerization activities of comonomers such as L-lactide, γ-butyrolactone, δ-octanolactone, δ-decanolactone, or ω-pentadecalactone with CL by yttrium triflate were very low at 60°C. Direct molding method during polymerization of PCL at 40°C by yttrium triflate was developed. It was found that this direct molding PCL (Mn = 2000, Mw/Mn = 3.07) was biodegraded very slowly in a buffer (pH 7.0) with a lipase produced by Rhizoupus arrhizus.