This study presents the synthesis and characterization of a series of multiblock copolymers, poly(ethylene 2,5-furandicarboxylate)-poly(ε-caprolactone) (PEF-PCL), created through a combination of the two-step melt polycondensation method and ring opening polymerization, as sustainable alternatives to fossil-based plastics. The structural confirmation of these block copolymers was achieved through Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), ensuring the successful integration of PEF and PCL segments. X-ray Photoelectron Spectroscopy (XPS) was employed for chemical bonding and quantitative analysis, providing insights into the distribution and compatibility of the copolymer components. Differential Scanning Calorimetry (DSC) analysis revealed a single glass transition temperature (T_g), indicating the effective plasticizing effect of PCL on PEF, which enhances the flexibility of the copolymers. X-ray Diffraction (XRD) studies highlight the complex relationship between PCL content and crystallization in PEF-PCL block copolymers, emphasizing the need to balance crystallinity and mechanical properties for optimal material performance. Broadband Dielectric Spectroscopy (BDS) confirmed excellent distribution of PEF-PCL without phase separation, which is vital for maintaining consistent material properties. Mechanical properties were evaluated using Nanoindentation testing, demonstrating the potential of these copolymers as flexible packaging materials due to their enhanced mechanical strength and flexibility. The study concludes that PEF-PCL block copolymers are promising candidates for sustainable packaging solutions, combining environmental benefits with desirable material properties.

Copper selenides are attractive materials for high-temperature thermoelectric applications. They exhibit remarkably enhanced thermoelectric properties originating from their superionic liquid character. In this work, the synthesis of Cu-Se compounds is investigated using mechanical alloying, aiming to obtain the Cu2Se phase and modify the crystal structure by annealing at high temperatures and quenching. In the first part, Cu-Se powders are prepared at various milling times. They are characterized regarding their structure, morphology and composition by X-ray diffraction analysisand scanning electron microscopy. After 2.5 h of synthesis,α-Cu2Se andβ-Cu2Se was attained in the powder, with the former having the highest percentage contribution. The crystallite size of these phases was calculated to be in the range of 17.0-19.6nm. The synthesized powder consisted of grains with dimensions from nanometers to micrometers and their aggregates. A trace of a possibly surficial layer of copper oxide was also detected on the sample. In the second part of this study, the optimum synthesized powder wassubjected to 2 hof annealing at 650 °C, followed by quenching. According to X-ray diffraction analysis,the percentage contribution of the thermoelectrically inferiorα-Cu2Se phase increased being the vast majority of the material and almost eliminated β-Cu2Se. The crystallite size was calculated to be in the range of 31.2-34.5nm. Overall, the desired Cu2Se compound can be obtained by the mechanical alloying technique asα- and β-phase, and the crystal structure can be modified by annealing under appropriate conditions.