Unveiling the uncommon crystallization features of 3, 4-PEF, a thermal and DFT study

abstract

The development of furandicarboxylic acid (FDCA) based polymers and materials is a rapidly growing research field in both academia and industry, driven by the need to replace fossil-based polymers with more sustainable alternatives. Despite the unequivocal potential of poly(ethylene 2,5-furandicarboxylate) (2,5-PEF), many other furanic polyesters, such as poly(ethylene 3,4-furandicarboxylate) (3,4-PEF), synthetized from the 3,4-FDCA isomer, remain underexplored. This study is the first to explore the conformational preferences of 3,4-PEF polyester using vibrational spectroscopy and density functional theory calculations. Additionally, a comprehensive thermal characterization of 3,4-PEF addresses current gaps in the literature. The results suggest that, in crystalline domains, 3,4-PEF chains adopt a conformation where the 3,4-FDCA segment exhibits a syn-syn motif and the ethylene glycol (EG) segment is in the trans conformation (ss-t). In amorphous regions, however, multiple conformations coexist, with syn-syn-gauche (ss-g) and anti-syn-gauche (as-g) segments accounting for the bulk of the population distribution. As previously observed for 2,5-PEF, the formation of C–H⋯O interactions in the crystalline domain is the main driver for the crystallization preferences of 3,4-PEF. The energetic gain from interchain C–H⋯O bond formation compensates for the energy penalty associated with the ss-g/as-g to ss-t conformational transition. Differential scanning calorimetry (DSC) analysis revealed that 3,4-PEF has a glass transition temperature (Tg) of 39 °C and a melting temperature (Tm) of 155 °C. Kinetic studies showed that the fastest crystallization rate for 3,4-PEF occurs at 110 °C, with a half crystallization time of 12 min. Interestingly, 3,4-PEF crystallizes faster than 2,5-PEF at its optimal crystallization temperature (170 °C), though still more slowly than poly(ethylene terephthalate). These findings suggest that 3,4-PEF holds promise as a renewable polymer with fast crystallization behaviour.

authors

Simão V Pandeirada, Catarina F Araújo, Mariela M Nolasco, Pedro D Vaz, Svemir Rudić, Armando JD Silvestre, Nathanael Guigo, Paulo Ribeiro-Claro, Andreia F Sousa

Groups

G4 - Renewable Materials and Circular Economy
G6 - Virtual Materials and Artificial Intelligence

Projects

CICECO - Aveiro Institute of Materials (UIDB/50011/2020)

CICECO - Aveiro Institute of Materials (UIDP/50011/2020)

Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)

European network of FURan based chemicals and materials FOR a Sustainable development (FUR4Sustain)

acknowledgements

This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 (DOI 10.54499/UIDB/50011/2020), UIDP/50011/2020 (DOI 10.54499/UIDP/50011/2020) & LA/P/0006/2020 (DOI 10.54499/LA/P/0006/2020), financed by national funds through the FCT/MCTES (PIDDAC). The FCT is also acknowledged for the research contract under Scientific Employment Stimulus to AFS (CEECIND/02322/2020) (DOI 10.54499/2020.02322.CEECIND/CP1589/CT0008) and for the Ph.D grants to CFA(SFRH/BD/129040/2017) and SVP (2023.01628.BD). This publication is based upon work from COST Action FUR4Sustain, CA18220, supported by COST (European Cooperation in Science and Technology).