Bioinspired All‐Polyester Diblock Copolymers Made from Poly(Pentadecalactone) and Poly(3,4‐Ethylene Furanoate): Synthesis and Polymer Film Properties

Bio‐based, fully degradable aliphatic‐aromatic block copolymers are synthesized from ω‐pentadecalatone and cyclic oligo(3,4‐ethylene furanoate). In the first approach, the ring‐opening polymerization of the cyclic oligo(3,4‐ethylene furanoate) is initiated by a poly(pentadecalactone) macroinitiator with a terminal hydroxy group. The reaction temperatures of the melt polymerization are 210–230 °C due to the high melting points of the oligo(3,4‐ethylene furanoate). Under these conditions, transesterification is observed. The blockiness of the reaction products depends on the reaction temperature and on the ratio of pentadecalactone to 3,4‐ethylene furanoate repeat units, which is 50:50, 80:20, and 90:10. At lower temperatures and more pentadecalactone content, the blockiness is larger. The number average molar mass of the block copolymers remains smaller than 20 000 g mol −1 . In the second approach, poly(pentadecalactone) is functionalized with an alkyne group, and the OH group of the oligo(3,4‐ethylene furanoate) (molar mass 1900 g mol −1 ) is converted into an azide group. Connecting the two polymers in a copper‐catalyzed 1,3‐dipolar addition reaction (“click reaction”) yields block copolymers with a number average molar mass of 12 400 g mol −1 . The mechanical properties of the polymer films are intermediate between those of the parent homopolymers.