Synthesis and structure – property relationship of biobased poly(butylene 2,5-furanoate) – block – (dimerized fatty acid) copolymers

Theoretical approach to the crystal structure of poly(butylene 2,5-furandicarboxylate) as revealed by density functional theory

In this work, we present a new model of the crystalline structure of the poly(butylene 2,5-furandicarboxylate) (PBF). This new structure has been derived using an ab initio density functional theory methodology and focusing on the agreement between the experimental and theoretical x-ray diffraction patterns. An extensive study has been performed to analyze the possible conformations that the polymeric strand can adopt in its crystalline form, leading to 60 initial crystalline structures. Due to thermal motion, which cannot be easily tackled with the ab initio methodology, and small inaccuracies, which are intrinsic to this calculation method, the theoretical unit cell dimensions can slightly differ from those obtained in the crystallization experiments. Thus, a structural refinement method has been employed to overcome these discrepancies and procure a crystalline structure whose x-ray diffraction pattern is consistent with the experimental one. For the proposed crystalline structure of PBF, both the powder diffraction pattern and the fiber diffraction diagram show a remarkable agreement with those available in the literature.

Enzymatically catalyzed furan-based copolyesters containing dilinoleic diol as a building block

A more environmentally friendly method for creating sustainable alternatives to traditional aromatic-aliphatic polyesters is a valuable step towards resource-efficiency optimization. A library of furan-based block copolymers was synthesized via temperature-varied two-step polycondensation reaction in diphenyl ether using Candida antarctica lipase B (CAL-B) as a biocatalyst where dimethyl 2,5-furandicarboxylate (DMFDCA), α,ω-aliphatic linear diols (α,ω-ALD), and bio-based dilinoleic diol (DLD) were used as the starting materials. Nuclear magnetic spectroscopy (¹H and ¹³C NMR), Fourier transform spectroscopy (FTIR) and size exclusion chromatography (SEC) were used to analyze the resulting copolymers. Additionally, crystallization behavior and thermal properties were studied using X-ray diffraction (XRD), digital holographic microscopy (DHM), and differential scanning microscopy (DSC). Finally, oxygen transmission rates (OTR) and dynamic mechanical analysis (DMTA) of furan-based copolyesters indicated their potential for medical packaging.

New Random Aromatic/Aliphatic Copolymers of 2,5-Furandicarboxylic and Camphoric Acids with Tunable Mechanical Properties and Exceptional Gas Barrier Capability for Sustainable Mono-Layered Food Packaging

High molecular weight, fully biobased random copolymers of 2,5-furandicarboxylic acid (2,5-FDCA) containing different amounts of (1R, 3S)-(+)-Camphoric Acid (CA) have been successfully synthesized by two-stage melt polycondensation and compression molding in the form of films. The synthesized copolyesters have been first subjected to molecular characterization by nuclear magnetic resonance spectroscopy and gel-permeation chromatography. Afterward, the samples have been characterized from a thermal and structural point of view by means of differential scanning calorimetry, thermogravimetric analysis, and wide-angle X-ray scattering, respectively. Mechanical and barrier properties to oxygen and carbon dioxide were also tested. The results obtained revealed that chemical modification permitted a modulation of the abovementioned properties depending on the amount of camphoric co-units present in the copolymers. The outstanding functional properties promoted by camphor moieties addition could be associated with improved interchain interactions (π-π ring stacking and hydrogen bonds).

Hytrel-like Copolymers Based on Furan Polyester: The Effect of Poly(Butylene Furanoate) Segment on Microstructure and Mechanical/Elastic Performance

This paper aims to compare the performance of two Hytrel-like segmented copolymers: “classic” PBT-b-PTMG and fully bio-based PBF-b-PTMG, containing poly(butylene furanoate) as the rigid segment. The idea behind this research is to assess whether the sustainable copolymers can successfully replace those “classic” once at the thermoplastic elastomers’ market. Two series of copolymers were synthesized under the same process parameters, had the same compositions, but differed in aromatic ring structure in terephthalate/furanoate unit. Furthermore, the materials were processed by injection moulding as typical Hytrel products. Then, the samples were subjected to extensive characterisation including NMR, GPC, FTIR, DSC, WAXS, DMTA, TGA techniques and mechanical tests with particular interest in the microstructure formed during processing and its effect on the copolymers’ mechanical and elastic behaviour. The detailed analysis proved that PBF-b-PTMG and PBT-b-PTMG copolymers represent two kinds of materials with similar chemical structure, some features of thermoplastic elastomers, but evident differences in their physical properties.

Supramolecular structure, relaxation behavior and free volume of bio-based poly(butylene 2,5-furandicarboxylate)-block-poly(caprolactone) copolyesters

In the present study, a fully plant-based sustainable copolyester series, namely poly(butylene 2,5-furandicarboxylate)-block-poly(caprolactone)s (PBF-block-PCL)s were successfully synthesized by melt polycondensation combining butylene 2,5-furandicarboxylate with polycaprolactone diol (PCL) at different weight ratios. Differential scanning calorimetry (DSC) showed that only PBF underwent melting, crystallization from the melt, and cold crystallization. Thermogravimetric analysis (TGA) revealed outstanding thermal stability, exceeding 305 °C, with further improvement in thermal and thermo-oxidative stability with increasing PCL content. Broadband dielectric spectroscopy (BDS) revealed that at low temperatures, below the glass transition (T_g) all copolyesters exhibited two relaxation processes (β₁ and β₂), whereas the homopolymer PBF exhibited a single β-relaxation, which is associated with local dynamics of the different chemical bonds present in the polymer chain. Additionally, it was proved that an increase in PCL content affected the dynamics of the chain making it more flexible, thus providing an increase in the value of the room temperature free volume fractions (f_v) and the value of elongation at break. These effects are accompanied by a decrease in hardness, Young's modulus, and tensile strength. The described synthesis enables a facile approach to obtain novel fully multiblock biobased copolyesters based on PBF and PCL polyesters with potential industrial implementation capabilities.

Utility of Chemical Upcycling in Transforming Postconsumer PET to PBT-Based Thermoplastic Copolyesters Containing a Renewable Fatty-Acid-Derived Soft Block

Thermoplastic copolyesters (TPCs) are important structural components in countless high performance applications that require excellent thermal stability and outstanding mechanical integrity. Segmented multiblock architectures are often employed for the most demanding applications, in which semicrystalline segments of poly(butylene terephthalate) (PBT) are combined with various low T _g soft blocks. These segmented copolymers are nearly always synthesized from pristine feedstocks that are derived from fossil-fuel sources. In this work, we show a straightforward, one-pot synthetic approach to prepare TPCs starting from high-molar mass poly(ethylene terephthalate) recyclate (rPET) combined with a hydrophobic fatty acid dimer diol flexible segment. Transesterification is exploited to create a multiblock architecture. The high molar mass and segment distribution are elucidated by detailed size-exclusion chromatography and proton and carbon nuclear magnetic resonance spectroscopy. It is also shown that rPET can be chemically converted to PBT through a molecular exchange, in which the ethylene glycol is substituted by introducing 1,4-butane diol. A series of copolymers with various compositions was prepared with either PET or PBT segments and the final thermal properties and mechanical performance is compared between the two different constructs. Ultimately, PBT-based TPCs crystallize faster and exhibit a higher modulus over the range of explored compositions, making them ideal for applications that require injection molding. This represents an ideal, sustainable approach to making conventional TPCs, utilizing recyclate and biobased components to produce high performance polymer constructs via an easily accessible upcycling route.

Microstructure and Mechanical/Elastic Performance of Biobased Poly (Butylene Furanoate)-Block-Poly (Ethylene Oxide) Copolymers: Effect of the Flexible Segment Length

The aim of this paper is to extend knowledge on biobased poly(butylene furanoate)–block–poly (ethylene oxide) (PBF-b-PEO) copolymers’ performance by studying the effect of the PEO segment’s molecular weight on the microstructure and materials behavior. As crystallization ability of PEO depends on its molecular weight, the idea was to use two PEO segment lengths, expecting that the longer one would be able to crystallize affecting the phase separation in copolymers, thus affecting their mechanical performance, including elasticity. Two series of PBF-block-PEOs with the PEO segments of 1000 and 2000 g/mol and different PBF/PEO segment ratios were synthesized by polycondensation in melt, injection molded to confirm their processability, and subjected to characterization by NMR, FTIR, DSC, DMTA, WAXS, TGA, and mechanical parameters. Indeed, the PEO2000 segment not only supported the crystallization of the PBF segments in copolymers, but at contents at least 50 wt % is getting crystallizable in the low temperature range, which results in the microstructure development and affects the mechanical properties. While the improvement in the phase separation slightly reduces the copolymers’ ability to deformation, it is beneficial for the elastic recovery of the materials. The investigations were performed on the injection molded samples reflecting the macroscopic properties of the bulk materials.

Sustainable and rapidly degradable poly(butylene carbonate-co-cyclohexanedicarboxylate): influence of composition on its crystallization, mechanical and barrier properties

Sustainable and fast biodegradable PBCCEs copolyesters have potential applications in green packaging and tissue engineering.