Among novel renewable
furanoate-based polyesters, poly(pentamethylene
2,5-furandicarboxylate) (PPeF) shows outstanding gas barrier properties
and high flexibility. PPeF blending/copolymerization with another
well-known bio-based polymer, poly(lactic acid) (PLA), leads to considerably
better mechanical and gas barrier properties of the latter, making
it suitable for flexible food packaging applications. In this work,
enzymatic depolymerization of PLA/PPeF blends with different compositions
(1, 3, 5, 20, 30, and 50 wt % PPeF) and a PLA-PPeF block copolymer
(50 wt % PPeF) by cutinase 1 fromThermobifida cellulositilytica(Thc_Cut1) was investigated
as a possible recycling strategy. Based on quantification of weight
loss and high-performance liquid chromatography (HPLC) analysis of
released molecules, faster hydrolysis was seen for PLA/PPeF blends
with increasing PPeF content when compared to neat PLA, while the
block copolymer (P(LA50PeF50)) was significantly less susceptible
to hydrolysis. Surface morphology analysis (via scanning electron
microscopy), Fourier transform infrared spectroscopy, and NMR analysis
confirmed preferential hydrolysis of the PPeF component. Through crystallization,
2,5-furandicarboxylic acid was selectively recovered from the depolymerized
films and used for the resynthesis of the PPeF homopolymer, demonstrating
the potential of enzymes for novel recycling concepts. The possibility
of selective recovery of 2,5-furandicarboxylic acid from the completely
depolymerized films with a 75% yield could bring further evidence
of the high value of these materials, both in the form of blends and
copolymers, for a sustainable whole packaging life cycle, where PPeF
is potentially enzymatically recycled and PLA is mechanically recycled.