Vitrimers constitute a new class of covalent adaptable networks (CANs), in which thermally stimulated associative exchange reactions allow the topological rearrangement of the dynamic network while keeping the number of the bonds and crosslink density constant. The current study proposed a solvent-free method to synthesize vitrimers by reactive melt mixing using a commercial biobased/biodegradable polyester, poly(butylene succinate), PBS. More specifically, a two-step process was followed; the first step involved reactive mixing of PBS with the crosslinker (diglycidyl ether of bisphenol A, DGEBA) and the transesterification catalyst (Zinc(II) acetylacetonate hydrate, Zn(acac)₂) in a twin-screw mini-compounder, in order to incorporate the epoxy groups in the polymer backbone. The second step (vitrimerization) comprised a crosslinking process of the homogenous mixtures in a vacuum oven at 170 ˚C, resulting in the formation of a dynamic crosslinked network with epoxy moieties serving as the crosslinkers. By tuning the crosslinker content (0 − 10% mol with respect to PBS repeating unit) and the Zinc(II) catalyst to crosslinker ratio (0 to 1), tailor-made vitrimers were prepared with high insolubility and improved melt strength. Moreover, PBS vitrimers could still be reprocessed by compression molding after the crosslinking, which enables recycling process.

This work was supported and funded by the “Basic Research Program, NTUA, PEVE”, grant agreement 51449/5.11.2020, of the National Technical University of Athens and is gratefully acknowledged.

Zinc oxide is an active, inorganic material for a number of important applications. Zinc Oxide have wide properties for industrial applications which has been further increased by making the use of it in nanoscale size that fit in the corrosion resistant coatings. Nanoparticles have unique properties such as large surface area and nanoscale size due to which it possess various application in coatings and paints. Coating is a covering which when applied to the surface forms a layer and act as a protective barrier to the surface based on the property of the coating. Nanocomposite coatings are comparatively low cost and have more applications like dealing with the corrosion and radiation resistivity. Incorporation of nanoparticles in coating enhance its property by reducing the void and expected to induce barrier property for corrosion.

For this purpose, zinc oxide nanoparticles were synthesized using wet chemical method. The effect of reactants (base) used in ZnO synthesis was studied from pH 9 to 11 and was characterized using XRD, FT-IR, SEM-EDX, etc. To increase the hydrophobicity and to make them suitable to disperse in polymeric binder, synthesized ZnO nanoparticles, have been surface modified with different silanes such as aminopropyl triethoxy silane (APTES), hexadecyl trimethoxy silane (HDTMS) and vinyltriethoxy silane (VTES). Surface modification was examined by FTIR, TGA, SEM-EDX and Contact angle analysis and VTES was found suitable for surface modification. Surface modified ZnO nanoparticles have been dispersed in polymeric binder (liquid EPDM) with other additives to form coating formulations. These coating formulations were applied on MS panels and it was observed that developed coating formulations have good mechanical and physical properties and high corrosion resistance.

As a metal-free abundant polymeric semiconductor, carbon nitride has numerous advantages for photo-based applications span from hydrogen evolution, CO2 reduction, ion transport, organic synthesis and organic dye degradation. In detail, graphitic carbon nitride (g-CN) synthesized from nitrogen-rich precursors via thermal polymerization resulting in efficient band gap along with tunable photoluminescence properties, enhances applied polymer supports after proper integration. Regarding that, recent publication detailed an integration process of organodispersible g-CN into highly commercialized resin called poly(styrene-co-divinylbenzene) through suspension photopolymerization is reported.¹ Moreover, surface activation of photo-active beads by endowing acid/base functionality was performed with visible light irradiation succesfully. Furtherly, successful transformation of g-CN embedded porous hydrogels from hydrophilic to hydrophobic via photoinduced surface modification based on g-CN photoactivity employing a non-toxic food additive molecule as a hydrophobization agent also performed.² Besides, subsequent pore substructuring via introducing secondary network photopolymerized within the pores was reported. The intention of this project was to mimic a water reservoir with nutrients for plants to provide a controllable releasing system by preventing water evaporation in soil applications.

Since g-CN is an organic semiconductor exhibiting sufficient charge separation under visible light illumination, a novel method for the oxidative photopolymerization of EDOT was successfully accomplished.³ Thanks to the absence of dissolved anions, so-formed neutral PEDOT is a highly viscous liquid that can be processed and post-doped easily.

Thanks for your consideration,

Best wishes

Cansu Esen

References

[1] C. Esen, M. Antonietti and B. Kumru*, J. App. Polym. Sci., 2021, 138, 50879.

[2] C. Esen and B. Kumru*, Beilstein J. Org. Chem., 2021, 17, 1323-1334.

[3] C. Esen, M. Antonietti and B. Kumru*, ChemPhotoChem, 2021, 5, 1-7.

In this work the preparation and subsequent mechanical and dynamic-mechanical characterisation of new biodegradable composite materials based on poly (butylene adipate terephthalate) (PBAT) loaded with zein-TiO₂ complex microparticles . The masterbatches of the materials were prepared by solvent casting with different filler contents (0 (pure PBAT), 5, 10 and 20 wt%), in order to modify and modulate the properties of the composite. Scanning electron microscopy (SEM) images showed homogeneous dispersion of the filler, without microparticles aggregation nor phase separation between filler and matrix, suggesting a good interphase adhesion. Mechanical characterization on dumbbell specimens, obtained by injection moulding, consisted in uniaxial tensile test at constant speed. The Young’s modulus (E) showed an actual improvement of the rigidity with the increase of the filler content. The yield stress (σ_y) presented a defined increase with growing percentage of filler, with opposite behaviour in comparison to the trend generally showed by other composite materials. Dynamic-mechanical analysis results exhibited an increasing trend in storage modulus (E’) values, confirming a greater rigidity of the composites with higher filler content. The values of the glass transition temperature (T_g) remained fairly constant, meaning that the thermal stability of the material was not affected by the addition of different amounts of protein complex microparticles. Overall, the produced PBAT composites showed similar properties to low density polyethylene (LDPE), proving to be promising and more sustainable alternatives to traditional non-biodegradable thermoplastic polymers commonly adopted in food and agricultural fields.