Search Results (153)

A versatile, sustainable feedstock pathway to bio-based polymeric materials was developed utilizing lignin biomass and the ring-opening copolymerization (ROCOP) of cyclic anhydrides and epoxides to synthesize functional, lignin-derived, fully bio-based polyester polyols. The initial goal was to make the ROCOP reaction more applicable to bio-derived starting materials and more attractive to commercialization by conducting the polymerization under less constrained and industrially relevant conditions in air and without the extensive purification of reagents, catalysts, or solvents, typically used in the literature. A refined ROCOP system was applied as a powerful tool in lignin valorization by successfully synthesizing the lignin-derived copolyester prepolymers from lignin models and depolymerized native lignin sourced from the reductive catalytic fractionation of Pinus radiata wood biomass. After mechanistic studies based on NMR characterization, an alternative ROCOP-style mechanism was proposed. This was found to be (1) contributing to the acceleration of the observed reaction rates with added [PPNCl] organo-catalyst and (2) ‘self-initiation/self-promoted’ ROCOP without any added external [PPNCl] catalyst, likely due to the presence of inherent [OH] groups/ species in the lignin-derived glycidyl ether monomer promoting reactivity. As a final goal, the potential of these lignin-derived polyesters as intermediate polyols was demonstrated by applying them in the synthesis of polyurethane (PU) film materials with a high biomass content of 75–79%. A dramatic range of thermomechanical properties was observed for the resulting materials, demonstrating how the ROCOP reaction can be used to tailor the properties of the functional polyester and PU material based on the nature of the epoxide and anhydride substrates used. These findings help endeavors towards predicting the relationship between chemical structure and material thermomechanical properties and performance, relevant for industrial applications. Overall, this study demonstrated the proof of concept that PU materials can be prepared from lignocellulosic biomass utilizing industrially feasible ROCOP of bio-derived cyclic anhydrides and epoxides. Full article

The development of hydrophilic biodegradable polymers is crucial for a range of biomedical applications, including targeted drug delivery and prosthetics. Ring-opening polymerization of substituted ε-caprolactone monomers provides an efficient method for the synthesis of polyesters with tailored properties. In this work, a synthetic approach for the preparation of ester- and morpholinoamido-disubstituted ε-caprolactone monomers was developed. Poorly defined polymers were obtained from the monomers, bearing two ester groups due to the competitive transesterification of the pendant substituents. On the other hand, the disubstituted morpholinoamido-ε-caprolactone was polymerized in a controlled manner by ring-opening polymerization, and amorphous homopolymers with a high glass transition temperature (112 °C) and good solubility in water were obtained. Statistical and block copolymers with the unsubstituted ε-caprolactone were also prepared, and DLS analysis of the amphiphilic block copolymers in water shows the presence of self-assembled particles. These results demonstrate the potential of morpholinoamido-functionalized ε-caprolactone derivatives as building blocks for the development of biodegradable polymeric materials for biomedical applications. Full article

Optical fiber composite insulators are essential for photoelectric current measurement, yet insulation failure at embedded optical fiber interfaces remains a major challenge to long-term stability. This study proposes a strategy to replace conventional silicone rubber with cycloaliphatic-like epoxy resin (CEP) as the shed-sheathing material. Three optical fibers with distinct outer coatings, ethylene-tetrafluoroethylene copolymer (ETFE), thermoplastic polyester elastomer (TPEE), and epoxy acrylate resin (EA), were evaluated for their interfacial compatibility with CEP. ETFE, with low surface energy and weak polarity, exhibited poor wettability with CEP, resulting in an interfacial tensile strength of 0 MPa, pronounced dye penetration, and rapid electrical tree propagation. Its average interfacial breakdown voltage was only 8 kV, and the interfacial leakage current reached 35 μA after hygrothermal aging. In contrast, TPEE exhibited high surface energy and strong polarity, enabling strong bonding with CEP, yielding an average interfacial tensile strength of approximately 46 MPa. Such a strong interface effectively suppressed electrical tree growth, increased the average interfacial breakdown voltage to 27 kV, and maintained the interfacial leakage current below 5 μA even after hygrothermal aging. EA exhibited moderate interfacial performance. Mechanism analysis revealed that polar ester and ether groups in TPEE enhanced interfacial electrostatic interactions, restricted the mobility of CEP molecular chain segments, and increased charge traps. These synergistic effects suppressed interfacial charge transport and improved insulation strength. This work offers valuable insight into structure–property relationships at fiber–resin interfaces and provides a useful reference for the design of composite insulation materials. Full article

The development of materials based on chitosan and polyesters that possess thermoplastic, biocompatible, and biodegradable properties is a perspective for additive technologies in biomedicine. Research on obtaining such compositions is constrained because the polysaccharide content does not exceed 5 wt.%, which cannot ensure effective tissue regeneration. Herein, we propose a method for obtaining thermoplastic block copolymers based on chitosan and poly(ε-caprolactone) by ultrasonic irradiation of a homogeneous solution of a homopolymer mixture in dimethyl sulfoxide as a common solvent, achieving a yield of 99%. The distinctive feature of the method is the interaction between the components at the molecular level and provides obtaining copolymers at any component ratio. SEM images revealed a homogeneous structure without structural defects in both solvent-cast films and extruded filaments. The block copolymers were characterized by high mechanical property tensile strength of up to 60–70 MPa and elasticity of up to 35% for films and 25–40 MPa and elasticity of up to 50% for filaments. Cell adhesion of composition investigated on fibroblast cells (hTERT BJ-5TA) is at the level of chitosan and demonstrated the absence of cytotoxicity. Full article

This paper proposes a new functionalized oligosiloxane as a comonomer for polyester, designed to provide hydrophobic surface properties and enhance low-temperature impact resistance. The functionalization of polymer resin itself has attracted attention in the context of monomaterialization. Chemically designing the primary structure of not only polymers but also monomers is crucial for enhancing the intrinsic performance of the resin. However, little is known about oligosiloxane monomers for polyester that can provide oligosiloxane-like properties such as hydrophobicity and flexibility at low temperatures. Here, we report the functional design of a polyester material through silicone copolymerization. A novel comonomer was designed and synthesized to optimize both the molecular structure and the compatibility of the silicone segments, promoting uniform copolymer formation. Incorporating silicone into the polymer matrix reduced surface energy, thereby improving water repellency. Furthermore, the flexibility imparted by the silicone components effectively mitigated the brittleness of polyester at sub-zero temperatures, resulting in superior impact resistance. Structural analysis, contact angle measurements, and low-temperature impact tests were conducted on the copolymers. The results confirmed that optimizing comonomer design enables significant enhancement of both hydrophobicity and impact durability, contributing to the development of high-performance polyester materials suitable for demanding environments. Full article

In this study, a poly [ε-caprolactam-co-bis(2-hydroxyethyl) terephthalate] copolymer (P (CL-co-BHET)) was synthesized from para-terephthalic acid (PTA), ethylene glycol (EG), and caprolactam (CL). The crystallization behavior and thermal stability of the copolymer were thoroughly investigated. With the aid of molecular simulation, this study investigated the variation in interchain hydrogen bonding in the copolymer, focusing on the direction and the number of hydrogen bonds. The results revealed a close relationship between the copolymer chain structure, the variation in interchain hydrogen bonding, and the crystallization behavior and thermal stability of the copolymer. The introduction of BHET segments disrupted the regularity of the PA6 backbone and hydrogen bonding, leading to a decrease in the melting point, crystallization temperature, and crystallinity of the copolymer. The thermal stability of the copolymers also decreased, and the crystallization form gradually shifted from the α-crystalline to the γ-crystalline phase. The findings of this study are significant for evaluating the crystallization behavior of polyester amides and for predicting and regulating the properties of polyesteramide polymers. Full article

Biodegradable polyesters serve as matrices in pharmaceutical applications for the controlled release of therapeutic agents. These polymers are essential in the advancement of drug delivery systems (DDSs) that facilitate the gradual drug release over a predetermined duration. Therefore, this study introduces the novel use of a diethyl zinc/propyl gallate catalytic system to synthesize glycolide/ε-caprolactone copolymers (PGCL) for subsequent biomedical applications. A total of twenty-four biodegradable copolymeric matrices, characterized by a highly random microstructure and an average molecular weight (M_n) ranging from approximately 27 to 62 kDa, were synthesized and analyzed. The resulting copolymer samples underwent Neutral Red Uptake (NRU) and Umu tests, revealing no signs of cyto- or genotoxicity. Furthermore, a hemolysis assay was conducted on selected samples, indicating their suitability for intravenous administration. Finally, a release study of paclitaxel (PACL) from one of the synthesized matrices demonstrated a sustained and highly controlled drug release profile, following first-order kinetics and the Fickian diffusion mechanism. Full article

Unsaturated macrolactones (UMs) have long attracted researchers’ attention due to a combination of a reactive ester fragment and C=C bond in their structures. UMs of natural origin are comparatively few in number, and the task of developing synthetic approaches to new UMs is relevant. Recent advances in the synthesis of UMs cannot be dissociated from the progress in design of metathesis catalysts, since this catalytic approach is an atom-economy alternative to conventional organochemical methods. In the present review, we summarized and discussed the use of ring-closing metathesis, catalyzed by Ru and Group 6 metal complexes, in the synthesis of Ums and the advantages and shortcomings of the catalytic approach to UMs in comparison with organochemical methods. In a separate section, the use of UMs in the synthesis of unsaturated polyesters, the functionalization of these (co)polymers, and the prospects for practical use of the material obtained are also presented. It is essential that the actual approaches to UMs are often based on the use of renewable feedstocks, thereby meeting Green Chemistry principles. Full article

This study investigates the impact of hydrolysis on the crystallization behavior of poly(butylene succinate-co-adipate) (PBSA), a biodegradable polyester. Hydrolysis was conducted in a controlled environment using phosphate-buffered saline at 70 °C to isolate the impact of hydrolytic degradation on the polymer’s properties. The consequent changes in molecular weight characteristics were tracked using gel permeation chromatography (GPC), revealing a decrease in both weight average molecular weight (M_w) and an increase in polydispersity index (PDI) as hydrolysis progressed. The thermal behavior of PBSA during hydrolysis was thoroughly investigated using differential scanning calorimetry (DSC), which demonstrated significant changes in melting temperature (T_m), glass transition temperature (T_g), and crystallinity (X). These changes in T_m and T_g suggest a change in copolymer composition, likely due to the greater susceptibility of the adipic acid unit to hydrolysis compared to the succinic acid unit. Furthermore, polarized optical microscopy (POM) was employed to observe the morphological evolution of PBSA, showing a transition from spherulitic structures in the early stages of hydrolysis to dendritic structures with prolonged hydrolysis time. The decrease in nucleation activity led to a reduction in the number of spherulites, which in turn allowed the remaining spherulites to grow larger. Full article

Poly(lactic acid) (PLA) is a widely used biobased polyester which can be derived from renewable resources. Due to its excellent properties, it has already been adopted in various industrial sectors. While PLA is compostable, its degradation to the environment is very slow, necessitating the development of efficient recycling methods. This study focuses on the chemical recycling via microwave-assisted alkaline hydrolysis of PLA and its copolymers with poly(ethylene azelate) (PEAz), aiming to recover both carboxylic acid monomers: lactic acid and azelaic acid. Moreover, our method tunes the degradation of PLA via the synthesis of the novel aliphatic PLA-based copolyesters, targeting engineering-like applications, specifically in the field of printed electronics. Various process parameters were analyzed, including the temperature and the duration of the experiments as well as different phase transfer catalysts. Complete degradation was achieved at low temperatures (110–125 °C) and short times (12–15 min) for the PLA-based copolyesters, offering significant environmental benefits, as considerably less energy is consumed compared to chemical conventional methods. So, by changing the composition of the copolyesters through the incorporation of PEAz blocky segments, the ester bonds became more susceptible to hydrolysis under alkaline conditions assisted with microwave irradiation. Additionally, enzymatic hydrolysis was also studied in parallel for comparative purposes, revealing low degradation rates, thus establishing the microwave-assisted alkaline hydrolysis as a solid and reliable method for tuning the degradation of PLA-based materials. Full article

Thermotropic polyesters are a subject of keen interest due to their exceptional heat resistance, thermal stability, and high strength. However, these thermal characteristics pose significant constraints on standard manufacturing processes, as the melting temperatures of these polymers can exceed 300 °C. This study explored the feasibility of manufacturing final items molded from prepolymers through a solid-state polymerization process. A copolymer composed of 4-acetoxybenzoic acid (4ABA), 3-acetoxybenzoic acid (3ABA), and 4′-acetoxybiphenyl-4-carboxylic acid (ABCA) was synthesized using melt polycondensation. To comprehensively evaluate the performance of the resulting material, several sets of samples were prepared, including those containing TiO₂. Experimental samples from the pre-polymers were obtained through injection molding followed by high-temperature solid-state post-polymerization. The final products underwent a range of tests, including rheological and mechanical analyses, as well as thermal evaluations. The products demonstrated sufficient strength and stability. The proposed method of solid-state post-condensation offers significant potential advantages for the practical application of manufacturing high-performance engineering materials. Full article

A compatibilizer for low-density polyethylene (LDPE)/poly(ethylene terephthalate) (PET) blends was developed. This compatibilizer consists of amine-functionalized PET, which is blended with maleated polyethylene to form a copolymer. The goal is to use this compatibilizer in the future for recycling plastic waste from the marine environment. Fourier-transform infrared spectroscopy confirmed the successful incorporation of amine groups into PET chains through the addition of p-phenylenediamine in a molten state. An increase in diamine content allowed for the visualization of three bands where PET reacted with the diamine. Differential scanning calorimetry suggested that the polyester chains were grafted onto the maleated polyethylene backbone, with crystallinity increasing up to 2.5% diamine content. Scanning electron microscopy (SEM) images showed that the LDPE/PET blend resulted in a continuous polyethylene matrix with a dispersed polyester phase. The blend compatibilized with modified maleated polyethylene, and functionalized PET exhibited an improved interface. Oscillatory rheology and dynamic mechanical analysis indicated that the developed compatibilizer positively impacted the mechanical properties of the compatibilized LDPE/PET blends. This new approach enables the creation of innovative strategies for enhancing the properties of pre-existing polyolefin/polyester recycled blends. Full article

The materials used as filaments for additive techniques should exhibit various properties depending on the application and the requirements. The motivation for this study was the need to obtain a filament exhibiting appropriate aesthetic (metal-like) and mechanical properties. Glycol-modified poly(ethylene terephthalate) copolymer (PETG) and micrometric steel powder were used for composite preparation. Subsequently, the obtained material was used as a filament for 3D printing, i.e., by fused deposition modeling (FDM) technique. The physicochemical properties of the obtained filaments were determined, such as morphology (roughness), moisture sorption ability, thermal properties, and mechanical performance (tensile and compressive strength). Importantly, the metal filler did not modify the thermal properties of the polyester matrix, indicating that the filament containing steel microfiller could be processed using the same parameters as for neat PETG. The thermal stability was slightly enhanced after steel powder addition (for 13 wt.% content, the temperature of 75% weight loss was 466 °C; for comparison, that for the reference sample was 446 °C). The reinforcing effect of steel microfiller was noted based on mechanical performance measurements. The steel particles acted as a stiffening agent; the highest maximal tensile strength was observed for the composite with 3 wt.% steel powder content (ca. 68 MPa). Further increasing the microfiller load resulted in a slight decrease in the value of this parameter. A different trend was reported considering the compressive strength, i.e., the value of this parameter increased with steel content. Based on the obtained results, the new PETG composites could be applied as structural materials. Full article

Biodegradable polyesters have been researched intensively over the last two decades because of their biodegradability and superb physical properties. However, the use of linear biodegradable polyesters, for the preparation of drug delivery systems (DDS), is hampered by several limitations. In view of this, scientific attention has been shifted to the employment of branched-chain (co-)polymers. In this context, we present herein the development of new melatonin (MLT) tablet formulations, using novel branched polylactide (PLA)-based copolymers of different architectures. Specifically, three PLA-polyol branched polyesters, namely, a three-arm copolymer based on glycerol (PLA-glycerol), a four-arm copolymer based on pentaerythritol (PLA-pentaerythritol), and a six-arm copolymer based on sorbitol (PLA-sorbitol), were utilized. The presence of these polyesters in the formulations was found to be crucial, as the sought MLT release, regarding its use in confronting sleep onset and/or sleep maintenance dysfunctions, was achieved. The copresence of the other excipients in the matrix tablets (lactose monohydrate, hydroxypropylmethylcellulose, microcrystalline cellulose, and sodium alginate) led to a concentration-dependent synergistic effect on the MLT release. To the best of our knowledge, this is the first investigation with these specific polymeric materials, concerning MLT modified release from matrix tablets. Full article

The study investigated the effect of Vinnex^® (vinyl acetate polymer) and Joncryl^® (epoxy-based copolymer) as compatibilizers on the mechanical properties of thermoplastic starch (TPS) and polybutylene adipate-co-terephthalate (PBAT) and polybutylene succinate-co-adipate (PBSA) films. Due to TPS’s hydrophilicity and brittleness, blending it with biodegradable polyesters like PBAT enhances its properties but may introduce compatibility challenges. This research evaluated three formulations (TPS/PBAT with Vinnex, TPS/PBAT with Joncryl, and TPS/PBAT with both additives) along with the inclusion of a polybutadiene succinate-co-adipate (PBSA) matrix to further improve performance. Mechanical testing (tensile strength, elongation at break, Young’s modulus) reveals that Vinnex and Joncryl enhance plasticization and polymer compatibility, positively impacting TPS/PBAT’s mechanical properties. The introduction of the PBSA matrix further improves tensile strength and elongation. Scanning electron microscopy (SEM) confirms better additive dispersion and interfacial adhesion within the blend. Complementary analysis includes melt flow index, melt density, DSC, and TGA, providing a comprehensive understanding of how these additives optimize TPS/PBAT compounds for sustainable applications. Mechanically, the compatibilized blends showed improved performance: Vinnex mainly enhanced stiffness, Joncryl primarily improved elongation, and a synergistic effect was observed with their combination. Full article