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•Poly(ethylene 2,5-furan dicarboxylate) was prepared using 4 different catalysts.•Effect of these catalysts on PEF recyclability was evaluated after 3 remelting cycles.•Titanate ...catalysts accelerate PEF degradation during re in higher extend than tin catalysts.•Used catalysts affect PEF decomposition mechanism studied by Py-GC/MS.
In the present work, poly(ethylene furanoate) (PEF) was synthesized via two-stage melt polycondensation process, using four different catalysts, namely tetrabutyl titanate (TBT), titanium(IV) isopropoxide (TIS), tin(II) 2-ethylhexanoate (TEH) and dibutyltin(IV) oxide (DBTO). In all reactions, 2,5-dimethylfuran-dicarboxylate (DMFD), ethylene glycol (EG) (1:2 molar ratio) and 400ppm of catalyst were used. The effect of these catalysts on the remelting and decomposition mechanism of PEF was studied. All polyesters were remelted up to three times, and for every melting cycle the intrinsic viscosity (IV) values and the carboxyl end group content were measured. It was found that after every melting, the IV was reduced while the COOH number was increased. Also, all samples have been studied with Fourier Transformed-Infrared Spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. It was found that the molecular weight reduction also affects the thermal properties of the polyesters. The decomposition mechanism of the prepared polyesters was studied using pyrolysis-gas chromatography/mass spectroscopy (Py-GC/MS).
Technological progress has made chemistry assume a role of primary importance in our daily life. However, the worsening of the level of environmental pollution is increasingly leading to the ...realization of more eco-friendly chemical processes due to the advent of green chemistry. The challenge of green chemistry is to produce more and better while consuming and rejecting less. It represents a profitable approach to address environmental problems and the new demands of industrial competitiveness. The concept of green chemistry finds application in several material syntheses such as organic, inorganic, and coordination materials and nanomaterials. One of the different goals pursued in the field of materials science is the application of GC for producing sustainable green polymers and membranes. In this context, extremely relevant is the application of green chemistry in the production of imprinted materials by means of its combination with molecular imprinting technology. Referring to this issue, in the present review, the application of the concept of green chemistry in the production of polymeric materials is discussed. In addition, the principles of green molecular imprinting as well as their application in developing greenificated, imprinted polymers and membranes are presented. In particular, green actions (e.g., the use of harmless chemicals, natural polymers, ultrasound-assisted synthesis and extraction, supercritical CO
, etc.) characterizing the imprinting and the post-imprinting process for producing green molecularly imprinted membranes are highlighted.
In this paper, a novel kind of microcapsules containing 2-ethoxynaphtalene (neroline) was successfully synthesized into polyurethane shells through the interfacial polycondensation of β-cyclodextrin ...with 4,4’-methylene (bisphenyl isocyanate) (MDI) in direct emulsion. The IR spectroscopy was used, on the one hand to confirm the success of polymerization reaction leading to the polyurethane shell formation, but on the other hand to check the encapsulation efficiency of fragrance that accounts for 40%. Microcapsules’ spherical shape and particle size distributions were revealed by means of optical microscopy, scanning electron microscopy (SEM) observation, and small-angle light scattering measurement. The impregnation of neroline-loaded microcapsules on polyamide knitted fabric was tested as an application method at a yield of around 74%. Adhesion of synthesized microcapsules to textile materials was evaluated through microscopic observations. The durability of the impregnation effect was tested by SEM and UV-visible spectroscopy. Washing fastness test of the impregnated polyamide knitting proved that the loaded microparticles retained their efficiency after more than 35 washing cycles.
The beneficial effects of lanthanide incorporation into 0.94Na0.5Bi0.5TiO3-0.06BaTiO3 (BNT-BT) matrix on its functional properties were investigated. The conventional solid-state method was used for ...synthesizing samples. The structural refinement revealed that all samples crystallized in R3c rhombohedral symmetry. Raman spectroscopy study was carried out using green laser excitation and revealed that no clear perceptible variation in frequency is observed. Dielectric measurements unveiled that the introduction of rare earth obstructed the depolarization temperature promoted in BNT-BT, the diffusive phase transition decreasing with increasing lanthanide size. Only dysprosium addition showed comparable diffusion constant and dielectric behavior as the unmodified composition. Further, the comparison of the obtained ferroelectric hysteresis and strain-electric field loops revealed that only Dy-phase exhibited interesting properties comparing parent composition. In addition, the incorporation of lanthanides Ln3+ into the BNT-BT matrix led to the development of luminescence characteristics in the visible and near infrared regions, depending on the excitation wavelengths. The simultaneous occurrence of photoluminescence and ferroelectric/piezoelectric properties opens up possibilities for BNT-BT-Ln to exhibit multifunctionality in a wide range of applications.
The aim of this study was to investigate the effect of side chain size on the optical and charge transport properties of thin films prepared from novel conjugated polysulfide-based polymers. Three ...polymers, labeled P1, P2, and P3, were derived from polysulfide derivatives and had different arylene groups (5,5′- biphenylene, 4,4′-biphenylene, and 2,6-pyridylene). Optical analysis was performed using photoluminescence (PL) and UV–visible absorption spectroscopy, revealing an energy band gap of 2.41–3.02 eV; P1 emitted yellow, P2 blue-green, and P3 green. Cyclic voltammetry measurements of the electrochemical band gap and HOMO and LUMO energy levels revealed that the polymer exhibited p-type semiconductor activity; the electrical properties of diodes based on the ITO/polysulfide derivative/Al structure were explored through analysis of current-voltage characteristics. The current space charge limitation (SCLC) mechanism was used to model the behavior of these diodes; the P2 thin film layer exhibited higher mobility than the other layers. The relationship between the geometry of the polymer thin films and their optical and electrical properties was thoroughly investigated.
In this work, we report the synthesis of poly(ethylene furanoate) (PEF), catalyzed by three different catalysts, namely, titanium (IV) isopropoxide (TIS), tetrabutyltitanate (TBT), and dibutyltin ...(IV) oxide (DBTO), via the two-stage melt polycondensation method. Solid-state polymerization (SSP) was conducted at different reaction times (1, 2, 3.5, and 5 h) and temperatures 190, 200, and 205 °C, under vacuum. The resultant polymers were analyzed according to their intrinsic viscosity (IV), end groups (⁻COOH), and thermal properties, via differential scanning calorimetry. DSC results showed that the post polymerization process was favorable to enhance the melting point of the prepared PEF samples. As was expected, the intrinsic viscosity and the average molecular weight of PEF increased with the SSP time and temperature, whereas the number of carboxyl end-groups was decreased. A simple kinetic model was also developed and used to predict the time evolution of polymers IV, as well as the carboxyl and hydroxyl content of PEF during the SSP. From both the experimental measurements and the theoretical simulation results it was proved that the presence of the TIS catalyst resulted in higher transesterification kinetic rate constants and higher reaction rates. The activation energies were not much affected by the presence of different catalysts. Finally, using DBTO as a catalyst, the polyesters produced have higher crystallinity, and as a consequence, higher number of inactive carboxyl and hydroxyl groups.
A series of novel renewable copolymers based on poly(ethylene succinate) (PESu) and poly(isosorbide succinate) (PISSu), with the Isosorbide (Is)/PESu molar ratio varying from 5/95 to 75/25, were ...synthesized in-situ and studied in this work. A sum of characterization techniques was employed here for the structural and thermo-dynamical characterization. The sophisticated technique of dielectric spectroscopy, along with proper analysis, enabled the molecular dynamics mapping of both the local and segmental types, which is presented for such materials for the first time. With increasing the Is fraction, shorter copolymeric entities were gradually formed. Based on the overall findings, the systems were found to be homogeneous, e.g., exhibiting single glass transitions, with the two polymer segments being found to be excellently distributed. The latter is indirect, although strong, evidence for the successful copolymerization. The thermal degradation mechanism for the copolymers was exhaustingly explored employing analytical pyrolysis. The systems exhibited, in general, good thermal stability, according to the thermogravimetric analysis. Confirming one of the initial scopes for the present systems, isosorbide plays here the role of hardener (PISSu) over the soft polymer (PESu), and this is reflected in the monotonic increase of the glass transition temperature, Tg, from −16 to ~56 °C. The introduction of Is results in an increase in constraints (hardening of the matrix), while there seems to be an overall densification of the polymer (decrease of the free volume).
In this study, the synthesis of poly(ethylene furanoate) (PEF), catalyzed by five different catalysts-antimony acetate (III) (Sb Ac), zirconium (IV) isopropoxide isopropanal (Zr Is Ip), antimony ...(III) oxide (Sb Ox), zirconium (IV) 2,4-pentanedionate (Zr Pe) and germanium (IV) oxide (Ge Ox)-via an industrially common combination of melt polymerization and subsequent solid-state polymerization (SSP) is presented. In all reactions, proper amounts of 2,5-dimethylfuran-dicarboxylate (DMFD) and ethylene glycol (EG) in a molar ratio of DMFD/EG= 1/2 and 400 ppm of catalyst were used. Polyester samples were subjected to SSP procedure, under vacuum application, at different reaction times (1, 2, 3.5, and 5 h) and temperatures of 190, 200, and 205 °C. Carboxyl end-groups concentration (⁻COOH), intrinsic viscosity (IV), and thermal properties, via differential scanning calorimetry (DSC), were measured for all resultant polymers to study the effect of the used catalysts on the molecular weight increase of PEF during SSP process. As was expected, it was found that with increasing the SSP time and temperature, the intrinsic viscosity and the average molecular weight of PEF steadily increased. In contrast, the number of carboxyl end-groups content showed the opposite trend as intrinsic viscosity, that is, gradually decreasing during SSP time and temperature increase. It is worthy to note that thanks to the SSP process an obvious and continuous enhancement in the thermal properties of the prepared PEF samples was attained, in which their melting temperatures (
) and degree of crystallinity (
) increase progressively with increasing of reaction time and temperature. To predict the time evolution of polymers IV, as well as the hydroxyl and carboxyl content of PEF polyesters during the SSP, a simple kinetic model was developed. From both the theoretical simulation results and the experimental measurements, it was demonstrated that surely the Zr Is Ip catalyst shows the best catalytic characteristics compared to all other used catalysts herein, that is, leading in reducing-in a spectacular way-the activation energy of the involved both transesterification and esterification reactions during SSP.
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-
-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,
H, and
C 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.
A new anthracene-based polymer containing the isosorbide group in the side chain (PPVIs-An) has been synthesized via Wittig reaction. The polymer is soluble in common organic solvents and shows good ...film-forming abilities. The macromolecular structure was characterized by NMR and FT-IR spectroscopies. This organic material was investigated by differential scanning calorimetry and thermogravimetric analysis and showed an amorphous behavior with a T g of 48 °C. The surface property of the PPVIs-An film was analyzed by contact angle and by atomic force microscopy. The optical properties of this organic semi-conductor were investigated by UV–Visible absorption and photoluminescence spectroscopies. The polymer exhibits a blue fluorescence in dilute solution and a green emission in thin film. The introduction of the polar isosorbide groups shown to improve the PL intensity, and a quantum yield of 72 % was obtained. The absence of π–π interaction between the chromophore units in polymer thin layer at fundamental electronic state was observed, due to the presence of steric repulsions between anthracene and isosorbide groups. The HOMO–LUMO energy levels were determined by cyclic voltammetry. An ITO/PPVIs-An/Al single-layer device was elaborated and investigated using current–voltage measurements which show a turn-on voltage of 5.3 V. The conduction mechanism seems to be a space-charge-limited current with exponential trap distribution at high applied bias voltage. The electrical transport properties of this device were studied as a function of frequency (100 Hz–10 MHz) and applied bias in impedance spectroscopy analyses.
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