Isosorbide and 2,5-Furandicarboxylic Acid Based (Co)Polyesters: Synthesis, Characterization, and Environmental Degradation

Poly(2,5-furandicarboxylate)s incorporating aliphatic moieties represent a promising family of polyesters, typically entirely based on renewable resources and with tailored properties, notably degradability. This study aims to go beyond by developing poly(isosorbide 2,5-furandicarboxylate-co-dodecanedioate) copolyesters derived from isosorbide (Is), 2,5-furandicarboxylic acid (FDCA), and 1,12-dodecanedioic acid (DDA), and studying their degradation under environmental conditions, often overlooked, namely seawater conditions. These novel polyesters have been characterized in-depth using ATR-FTIR, ¹H, and ¹³C NMR and XRD spectroscopies and thermal analysis (TGA and DSC). They showed enhanced thermal stability (up to 330 °C), and the glass transition temperature increased with the content of FDCA from ca. 9 to 60 °C. Regarding their (bio)degradation, the enzymatic conditions lead to the highest weight loss compared to simulated seawater conditions, with values matching 27% vs. 3% weight loss after 63 days of incubation, respectively. Copolymerization of biobased FDCA, Is, and DDA represents an optimal approach for shaping the thermal/(bio)degradation behaviors of these novel polyesters.

Tailored design of renewable copolymers based on poly(1,4-butylene 2,5-furandicarboxylate) and poly(ethylene glycol) with refined thermal properties

New copolymers based on renewable PBF/PEGF are tailored to show advantageous processing features as compared to PBF (enlarged working temperatures and no crystallisation at slow rates).

Scale Effect on the Interface Reaction between PDMS-E Emulsion Droplets and Gelatin

In this study, the scale effect on the interface reaction between PDMS-E emulsion droplets and gelatin was studied systematically. The monodisperse α-[3-(2,3-epoxy-propoxy)propyl]-ω-butyl-polydimethylsiloxane (PDMS-E) emulsion droplets on different scales were prepared using a Shirasu porous glass (SPG) membrane with a 0.5 μm pore size. The zeta potential results showed that the surface charge density of PDMS-E droplets decreased with the droplet scale, and the variation went through three stages, which corresponded to the diameter ranges of 100-450, 450-680, and 670-800 nm, respectively. The results of Raman spectra indicated that the distribution concentration of head groups in surfactants decreased but the polar epoxy groups tend to be exposed on the interface with the increase in the droplet scale. This was conducive to the nucleophilic attack of amino groups in gelatin on the epoxy group. Thus, the conversion of amino groups was related to the scale of the PDMS-E droplet. This study might provide a proper way to control the rate of interfacial reaction between immiscible macromolecule monomers.

Effect of Different Pretreatment Methods on Birch Outer Bark: New Biorefinery Routes

A comparative study among different pretreatment methods used for the fractionation of the birch outer bark components, including steam explosion, hydrothermal and organosolv treatments based on the use of ethanol/water media, is reported. The residual solid fractions have been characterized by ATR-FTIR, ¹³C-solid-state NMR and morphological alterations after pretreatment were detected by scanning electron microscopy. The general chemical composition of the untreated and treated bark including determination of extractives, suberin, lignin and monosaccharides was also studied. Composition of the residual solid fraction and relative proportions of different components, as a function of the processing conditions, could be established. Organosolv treatment produces a suberin-rich solid fraction, while during hydrothermal and steam explosion treatment cleavage of polysaccharide bonds occurs. This work will provide a deeper fundamental knowledge of the bark chemical composition, thus increasing the utilization efficiency of birch outer bark and may create possibilities to up-scale the fractionation processes.

Apple russeting as seen through the RNA-seq lens: strong alterations in the exocarp cell wall

Russeting, a commercially important defect in the exocarp of apple (Malus × domestica), is mainly characterized by the accumulation of suberin on the inner part of the cell wall of the outer epidermal cell layers. However, knowledge on the underlying genetic components triggering this trait remains sketchy. Bulk transcriptomic profiling was performed on the exocarps of three russeted and three waxy apple varieties. This experimental design was chosen to lower the impact of genotype on the obtained results. Validation by qPCR was carried out on representative genes and additional varieties. Gene ontology enrichment revealed a repression of lignin and cuticle biosynthesis genes in russeted exocarps, concomitantly with an enhanced expression of suberin deposition, stress responsive, primary sensing, NAC and MYB-family transcription factors, and specific triterpene biosynthetic genes. Notably, a strong correlation (R(2) = 0.976) between the expression of a MYB93-like transcription factor and key suberin biosynthetic genes was found. Our results suggest that russeting is induced by a decreased expression of cuticle biosynthetic genes, leading to a stress response which not only affects suberin deposition, but also the entire structure of the cell wall. The large number of candidate genes identified in this study provides a solid foundation for further functional studies.