Bottle-grade polyethylene furanoate from ring-opening polymerisation of cyclic oligomers

Jan-Georg Rosenboom,Giuseppe Storti,Diana Kay Hohl,Massimo Morbidelli,Peter Fleckenstein

doi:10.1038/s41467-018-05147-y

Jan-Georg Rosenboom, Giuseppe Storti + Show 3 more

Open Access

https://doi.org/10.1038/s41467-018-05147-y

Copy DOI

Abstract

Polyethylene furanoate (PEF) represents a promising renewable resource-based bioplastic as replacement for fossil-based polyethylene terephthalate (PET) with improved material properties. However, the synthesis of PEF through conventional polycondensation remains challenging, since the time-intensive reaction leads to degradation and undesired discolouration of the product. Here we show the successful rapid synthesis of bottle-grade PEF via ring-opening polymerisation (ROP) from cyclic PEF oligomers within minutes, thereby avoiding degradation and discolouration. The melting point of such mixture of cyclic oligomers lies around 370 °C, well above the degradation temperature of PEF (~329 °C). This challenge can be overcome, exploiting the self-plasticising effect of the forming polymer itself (which melts around 220 °C) by initiation in the presence of a high boiling, yet removable, and inert liquid plasticiser. This concept yields polymer grades required for bottle applications (Mn > 30 kg mol−1, conversion > 95%, colour-free products), and can be extended to other diffusion-limited polymer systems.

Highlights

Polyethylene furanoate (PEF) represents a promising renewable resource-based bioplastic as replacement for fossil-based polyethylene terephthalate (PET) with improved material properties
We find that the polymer itself has a plasticisation effect due to its much lower melting point (~220 °C) than the cyclic oligomers: pure cyOEF added to a reactive PEF melt containing 0.1% initiator is converted to polymer within 20 min at 280 °C (Fig. 3b and Table 1, entry 3)
Superior mechanical strength complements the properties of PEF: about 50% higher tensile strength (76 vs. 50 MPa) and 70% higher

Summary

Introduction

Polyethylene furanoate (PEF) represents a promising renewable resource-based bioplastic as replacement for fossil-based polyethylene terephthalate (PET) with improved material properties. The melting point of such mixture of cyclic oligomers lies around 370 °C, well above the degradation temperature of PEF (~329 °C) This challenge can be overcome, exploiting the self-plasticising effect of the forming polymer itself (which melts around 220 °C) by initiation in the presence of a high boiling, yet removable, and inert liquid plasticiser. In order to overcome this issue, we exploit ring-opening polymerisation (ROP)[15] as a faster synthetic route for PEF to deliver sufficient molecular weight on significantly reduced time scales. In this process, the esterification by-products are removed prior to the actual polymerisation by forming macrocyclic oligomers in a diluted non-viscous environment. The application of a cyclic stannoxane catalyst together with effective plasticisation of the system enable the production of polymer grades required for the so-called green bottle (Mn > 30 kg mol−1, conversion > 95%, colour-free products)

Methods

Results

Conclusion