AB2 Functional Polyesters via Ring Opening Polymerization: Synthesis and Characterization

Abstract Aliphatic AB2 functional polyesters were conveniently prepared by the ring opening polymerization of ε‐caprolactone and L‐lactide in the presence of the AB2 functional initiator 2,2‐bis(hydroxymethyl)propionic acid (bis‐MPA) and Sn(Oct)2 as the catalyst. In L‐lactide polymerization, both bis‐MPA hydroxyl groups initiated the polymerization reaction, but for ε‐caprolactone polymerization this depended on the monomer to initiator to catalyst ratio. Initiation at two hydroxyl groups occurred at high monomer to initiator ([M]/[I]) ratio and at high Sn(Oct)2 to monomer ratio. The melting temperatures of the AB2‐functional PLLA and PCL polymers were comparable to linear polymers with a $\overline {DP}$ equal to the $\overline {DP}$ per arm in the polymer. magnified image