This study investigated the chemical recycling of poly(ethylene terephthalate) (PET) fiber residues from two sources—high-molar mass mooring ropes and low-molar mass textile-grade fibers—to produce functional oligomers. Glycolysis was carried out using polyethylene glycol (PEG400) as the depolymerizing agent, and two catalysts were assessed, zinc acetate and lithium octoate, with the latter reported on for the first time in this application. Reactions were performed for 180 min under mechanical stirring, inert atmosphere, reflux, and controlled heating. The resulting oligomers were characterized by Fourier-transform infrared spectroscopy (FTIR), hydroxyl and acidity indices, and thermogravimetric analysis (TGA). Both PET feedstocks showed high reactivity toward glycolysis. Monitoring the reactions by acidity index indicated that conversion reached equilibrium at approximately 120 min. ATR-FTIR confirmed the formation of ester and hydroxyl groups, consistent with oligomer structures. Glycolysis of PET derived from mooring ropes produced oligoesters with hydroxyl values of 228 and 242 mgKOH/g for zinc acetate and lithium octoate, respectively, and molar masses of 1296 and 1338 g/mol for zinc acetate and lithium octoate, respectively. These values are suitable for subsequent syntheses such as polyester polyol production.

Abstract Developing synthetic bone scaffolds that simultaneously meet mechanical, structural and biological requirements for load‐bearing applications remains a major challenge in bone tissue engineering. Traditional fabrication routes often suffer from poor phase control, limited bioactivity or complex multi‐step processes. In this study, we present a scalable one‐shot synthesis strategy for fabricating nanohydroxyapatite (nHA) reinforced polyurethane scaffolds tailored for bone repair. A series of ester‐based polyester polyols were synthesized by reacting succinic acid with 1,4‐butanediol (BDO) and diethylene glycol (DEG) at varying ratios and molecular weights. Among them, PB 75 DES300 (75:25 BDO:DEG, ca 300 g mol −1 ) emerged as the optimal formulation, combining mechanical strength, thermal stability and processability. Incorporation of nHA during polyester synthesis promoted uniform nanoparticle dispersion and enhanced scaffold architecture. At 1.5 wt% nHA, the scaffold achieved a 31% increase in compressive modulus and marked improvement in microphase separation, while maintaining high porosity. SEM and swelling analyses confirmed improved pore regularity and water absorption, and human mesenchymal stem cell culture demonstrated significantly enhanced cell adhesion. These results highlight the dual role of nHA as both a mechanical reinforcer and a bioactive agent. The proposed one‐pot method enables precise control over scaffold structure and composition, offering a robust and clinically relevant platform for bone regeneration. © 2026 Society of Chemical Industry.

Polyurethane (PU) adhesives are extensively employed in flexible packaging owing to their strong adhesion and excellent wettability. However, most conventional PU adhesives are petroleum-based, which has driven growing interest in biobased alternatives. In this article, we synthesized biobased PU adhesives for flexible packaging applications using 2,5-furandicarboxylic acid (FDCA) and carbon dioxide (CO2). FDCA-based polyols (FPs) (2500-3500 g mol-1) with processable viscosities were prepared from FDCA, succinic acid, and 1,3-propanediol. To further enhance adhesion by increasing hydrogen-bond density, the diol and triol containing urethane moieties were synthesized via CO2-utilization technology. In T-peel tests, the adhesives crosslinked with CO2-based triols exhibited the highest adhesion strength (986 gf/25 mm) and were compared with those crosslinked using petroleum-derived trimethylolpropane (TMP). The prepared adhesives exhibited low glass transition temperature (from -28 to -18°C), ensuring flexibility at room temperature. In addition, the synthesized adhesives could be degraded through base-catalyzed transesterification in ethanol/ethyl acetate, enabling clean substrate recovery. These sustainable FDCA/CO2-based PU adhesives demonstrate strong potential as alternatives to petroleum-derived adhesives for flexible packaging.

Rigid polyurethane (PUR) and polyisocyanurate (PIR) foams are widely used as thermal insulation materials due to their excellent thermal conductivity and low density. However, fire resistance remains a critical property determining their safe application in construction, transportation, and energy systems. This study provides a comparative overview of the fire behavior of PUR and PIR foams, focusing on structural aspects, decomposition mechanisms, flame retardancy, and performance of emission of toxic gases during the combustion process. Despite extensive studies on PUR and PIR foams, systematic comparative investigations addressing the combined influence of recycled PET-based polyester polyols, isocyanurate content, and fire-related properties-including thermal degradation, heat release, and toxic gas emissions-remain limited. PIR foams, characterized by higher isocyanate indices and the presence of isocyanurate rings, show superior thermal stability, reduced heat release rates, and enhanced char formation compared with PUR foams. Experimental analysis of thermal degradation (TGA/DTG) and heat release (cone calorimetry) confirms that PIR foams demonstrate higher resistance to ignition and slower fire propagation. The results emphasize the critical role of molecular architecture and crosslink density in shaping the fire performance of rigid foams, highlighting PIR systems as advanced insulation solutions for applications requiring stringent fire safety standards. The PIR foam was prepared using a polyester polyol derived from recycled PET, which could help in achieving better fire properties during the combustion process. Compared with PUR foams, PIR foams exhibited an approximately 50% reduction in peak heat release rate, an increase in char yield from about 3 wt.% to over 22 wt.%, and a shift of the main thermal degradation peak by approximately 55 °C toward higher temperatures, indicating substantially enhanced fire resistance.

Epoxy resins often require toughening to broaden their engineering applications, such as in durable concrete repair. This study addresses this need by developing high-performance polyurethane/epoxy (PU/EP) interpenetrating polymer networks (IPNs). The composites were synthesized via prepolymer and stepwise methods using polyether polyol (PPG-1000), isocyanate (MDI-50), and E51 epoxy. At an optimal PU prepolymer content of 15 wt%, the polyether-based IPNs achieved a balanced mechanical profile (tensile strength: 59.90 MPa; elongation at break: 6.46%; compressive strength: 69.99 MPa). Further tuning of the soft segment by introducing polyester polyol (PS-2412) yielded superior performance at a PS-2412/PPG-1000 ratio of 30/70. This formulation increased tensile and compressive strengths by 11.4% and 6.07% (to 66.74 MPa and 74.24 MPa), and dry and wet bond strengths by 12.1% and 36.3% (to 5.68 MPa and 4.62 MPa), respectively. The enhancement is attributed to the increased crosslinking density and more uniform network structure imparted by PS-2412, which improves stress distribution and interfacial adhesion. This work provides an effective soft-segment design strategy for fabricating toughened epoxy composites with robust mechanical and adhesive properties.

Systemic anticancer therapy causes a number of side effects; therefore, local drug release devices may play an important role in this area. In this study, we developed polyurethane-dendrimer foams containing different amounts of third-generation poly (amidoamine) dendrimers (PAMAM G3) to evaluate their ability to encapsulate and release the model anticancer drug doxorubicin (DOX), as well as their biocompatibility and effectiveness against normal and cancer cells in vitro. PU–PAMAM foams containing 10–50 wt% PAMAM G3 were prepared using glycerin-based polyether polyol and castor oil as co-components. Structural and rheological analyses revealed that foams containing up to 20 wt% PAMAM G3 exhibited a well-developed porous structure, while higher dendrimer loadings (≥30 wt%) led to irregular cell shapes, pore coalescence, and thinning of cell walls, and indicated a gradual loss of structural integrity. Rheological creep–recovery measurements confirmed the structural findings: moderate PAMAM G3 incorporation (≤20 wt%) increased both the instantaneous and delayed elastic modulus (E1 ≈ 130–140 kPa; E2 ≈ 80 kPa) and enhanced elastic recovery, reflecting improved cross-link density and foam stability. Higher dendrimer contents (30–50 wt%) caused a decline in these parameters and higher viscoelastic compliance, indicating a softer, less stable structure. The DOX loading capacity and encapsulation efficiency increased with PAMAM G3 content, reaching maximum values of 35% and 51% for 30–40 wt% PAMAM G3, respectively. However, the most sustained DOX release profiles were observed for matrices containing 20 wt% PAMAM G3. Analysis of cumulative release and kinetic modeling revealed a transition from diffusion-controlled release at low PAMAM contents to burst-dominated release at higher dendrimer loadings. Importantly, matrices containing 10–20 wt% PAMAM G3 also indicated selective anticancer action against squamous cell carcinoma (SCC-15) compared to non-cancerous human keratinocytes (HaCaT). Moreover, the DOX they released effectively destroyed cancer cells. Overall, PU–PAMAM foams containing 10–20 wt% PAMAM G3 provide the most balanced combination of structural stability, controlled drug release, and cytocompatibility. These materials therefore represent a promising platform as passive carriers in drug delivery systems (DDSs), such as local implants, anticancer patches, or bioactive wound dressings.

ABSTRACT 1,5‐Pentanediol (1,5‐PDO), produced via catalytic hydrogenolysis of furfural, is a valuable intermediate for polyester polyols, solvents, humectants, green coatings, and elastomers. Although noble metal catalysts exhibit high activity for this transformation, their practical application is hampered by high cost and frequently long reaction times. To address these issues, a Co‐CeO 2 /SiO 2 catalyst was prepared using a membrane‐dispersion microreactor, enabling precise control over catalyst morphology. The obtained catalyst possesses uniformly dispersed Co nanoparticles (∼10 nm) and a mesoporous structure (S BET : 88.9 m 2 /g). Under mild conditions (170°C, 4 MPa H 2 ), complete furfural conversion was achieved within 3 h, giving a 1,5‐PDO yield of 39.0%—a competitive result compared with many reported systems. Furthermore, the catalyst maintained excellent stability over five consecutive cycles with only minimal activity loss (< 5%). This work highlights the potential of microreactor‐assisted synthesis in developing efficient non‑precious metal catalysts and provides a practical strategy for biomass valorization that balances performance, efficiency, and scalability.

This study investigates the substitution of fossil-based isocyanates with bio-based alternatives in polyurethane resin (PU) coatings and polyurethane dispersion (PUD) coatings, focusing on mechanical and thermal performance. The coatings were formulated using bio-based pentamethylene diisocyanate (PDI) and a range of fossil-based hexamethylene diisocyanate (HDI) trimers, combined with either a polyester polyol or a polyacrylate polyol. Differential-scanning calorimetry analysis revealed that PDI-based coatings exhibit higher reactivity during crosslinking, resulting in higher glass transition temperatures. Thermogravimetric analysis showed lower thermal stability compared to HDI-based polyurethanes, indicating increased rigidity but reduced thermal resilience. Mechanical testing of the coatings on wood showed superior microhardness, scratch resistance, and wear resistance for PDI-based coatings, particularly when combined with polyester polyols. Microscopic surface evaluation and roughness analysis confirmed smoother morphologies and lower crack densities in PDI-polyester coatings. Gloss and water contact angle measurements further demonstrated improved surface uniformity and hydrophobicity for PDI-based coatings. The FTIR spectroscopy validated the chemical integrity and more intense hydrogen bonding for PDI-based coatings. The post-wear spectra indicated chemical oxidation and surface rearrangements in PDI-based systems and mechanical degradation with chain scission for HDI-based coatings. Overall, the study highlights that bio-based PDI trimers can effectively replace fossil-based HDI trimers in PU and PUD coatings without compromising mechanical performance, especially when paired with polyester polyols. These findings support the development of more sustainable polyurethane coatings with enhanced durability and environmental compatibility.

ABSTRACT This work explores the mechanism of stress‐induced dielectric response of graphene nanoplatelets loaded flexible polyurethane foam for potential sensing applications. The polyurethane foam composite is prepared by premixing graphene with polyether polyol and a blowing agent, followed by reaction with isocyanate. The mechanical properties show that the developed foam possesses admirable compressive strength. The bulk density is found to decrease with graphene loading. The wettability studies show the hydrophobic nature of the foam upon graphene loading. Cell morphology divulges information about the polymer matrix and dispersion of nanofillers in it. The thermal behavior of the foam is also noted at different levels of filler loading. The dielectric properties, such as capacitance and electrical conductivity, are studied under compression at varying frequencies and applied stresses, which show a gradient change in properties due to the formation of conductive pathways acting as charge carriers. The behavior of the nanofiller at the lower and higher frequencies reveals the charge transfer mechanism over this variation. The highest capacitance value of approximately 4.8 pF at 100 Hz under the highest applied strain (~80%) and the highest conductivity, 2.5 × 10 −3 μS/m at 80% strain with 5 kHz was recorded at 0.7 wt% graphene loading. Finally, the study gives insight into producing conductive polymeric foam that can be used as a stress sensor for novel applications such as in health care as a wearable sensor connected to the body, monitoring real‐time movement. As the emerging scenario requires a lightweight and heterogeneity, flexible polyurethane foam provides a good solution.

This research focuses on synthesizing thermoplastic polyurethane elastomers (TPUs) using a reactive mixing method in an internal mixer, aiming to overcome the viscosity-related challenges of traditional synthesis techniques. Two types of polyester polyols based on ethylene glycol (Polyester-E) and butane diol (Polyester-B) along with two diisocyanates (pure 4,4′-MDI and a mixture of 4,4′-MDI/2,4′-MDI), a butane diol (BDO) chain extender, and dibutyltin dilaurate (DBTDL) catalyst were used. The study examined one-step and two-step feeding methods to investigate how process parameters and reactant ratios affect TPU properties. Tensile testing and FTIR analysis revealed that higher hydrogen bonding index (HBI) improved mechanical strength. AFM images showed increased microphase separation with higher diisocyanate-to-polyol ratios, indicated by larger hard segment domains. DSC results confirmed reduced crystallinity and increased melting temperatures with higher hard segment content. Rheological analysis demonstrated that increasing hard segment content led to greater complex viscosity and storage modulus, suggesting improved rigidity and phase separation.

A biodegradable, lightweight substrate for facility-based stereoscopic planting was developed via a one-step polyurethane foaming process. The substrate was synthesized by incorporating a biomass mixture of bamboo charcoal and cassava flour into a polyurethane foam matrix. This study investigated the effects of varying the content ratios of polyether polyol, isocyanate, bamboo charcoal powder, and cassava flour on the structural and functional properties of the composite foam. Results indicated that the biomass blend significantly influenced the foam’s physicochemical properties, water retention capacity, hardness, and elasticity. Specifically, bamboo charcoal powder enhanced the porosity and degradation rate of the foam, whereas the swelling of cassava flour upon water absorption improved the matrix’s resilience and cohesion. A polyether polyol/isocyanate ratio of 4:1 yielded a substrate with superior physicochemical properties, water retention capacity, germination rate, seedling index, and plant dry weight. Subsequently, the optimal overall performance was achieved at a biomass/polyol–isocyanate ratio of 1:3. This optimal formulation exhibited a degradation rate of 6.24 ± 0.94%, porosity of 66.07 ± 1.10%, and water retention capacity of 86.03 ± 1.59%. Consequently, it also produced the highest seed germination rate (84 ± 5.16%), seedling index (12.49 ± 1.94), and mature plant dry weight (4.00 ± 0.51 g). Microscopic analysis confirmed that the biomass addition refined the substrate’s pore structure, leading to greater uniformity and stability of the internal pores. This enhancement reduced the foam’s susceptibility to collapse and improved its elasticity and cohesion, thereby making it more amenable to mechanized handling and planting operations.

Synthesis of starch-based polyether non-isocyanate polyurethane with excellent mechanical and foaming properties.

ABSTRACT Given the defects existing in traditional additive flame retardants, it is of great research significance to endow polyurethane (PU) with intrinsic flame retardancy through molecular structure design. The polyester polyol (PAHI) is first synthesized by esterification with 1, 6‐adipic acid, 1, 6‐hexanediol, and itaconic acid, and then the itaconic acid reacts with 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) to form a polyester polyol (PAHI‐DOPO). The PAHI‐DOPO monomer is used as part of PU flexible section to be cured with diphenylmethane diisocyanate (MDI) to obtain PU with an increased LOI value of 30.4% and flame‐retardant grades reaching the V‐0 level. Moreover, a small amount of PAHI‐DOPO can significantly enhance the mechanical properties of PU, resulting in a strength increase from 15.1 to 18.2 MPa and an improvement in toughness from 753% to 815%. Compared with direct addition of equal amount of DOPO as flame retardant, the transparency and mechanical properties of PU are significantly improved. Interestingly, the intrinsic flame‐retardant approach effectively avoids the sharp decrease in mechanical properties that occurs when the flame retardant migrates from the samples upon immersion in water. Thus, this synthetic flame‐retardant polyester polyol offers an efficient, durable, and environmentally friendly approach to enhancing the flame‐retardancy of PU.

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.

ABSTRACT This study presents a one‐pot emulsion polymerization that combines step‐growth process of methylene‐bis(4‐cyclohexylisocyanate) (HMDI) and polyether polyol (EP‐330N) to form polyurethane (PU) and chain growth radical polymerization of methyl methacrylate (MMA) and crosslinker ethylene dimethacrylate (EDMA) to produce crosslinked poly(methyl methacrylate) (PMMA). The as‐prepared interpenetrating PU‐PMMA hybrid latexes have features of tailored cross‐linking densities (gel content as high as 49.8%, controlled by the molar ratio of ─NCO/─OH, namely R ‐value), yielding colloidally stable particles (90–110 nm) with a spherical morphology. FTIR and Soxhlet extraction are employed to characterize the successful synthesis of hybrid particles. As‐proof of application, the PU‐PMMA particles have been used as a toughening modifier of poly(vinyl chloride) resin (PVC). The impact strength of PVC blends increases from 2.6 to 4.6 kJ/m 2 with 0–10 phr PU‐PMMA addition. These results demonstrate that the one‐pot emulsion polymerization integrating radical and step‐growth mechanisms could be considered as a straightforward, green emulsification method to synthesize interpenetrating hybrid particles with tunable properties.

We report the design and synthesis of a biodegradable hyperbranched polyether polyketal polyol, containing acid-labile ketal groups with controlled degradation, high water solubility, excellent hemocompatibility, and cell compatibility. For this, we have developed a new AB2-type acid-labile monomer, 2-((4-(2-(oxiran-2-ylmethoxy) ethoxy)tetrahydro-2H-pyran-4-yl)oxy)ethan-1-ol (OTPE). The OTPE monomer is copolymerized with glycidol through anionic ring-opening multibranching polymerization generating OTPE-incorporated hyperbranched polyglycerol (A-BioHPG) with varying degradable monomer content. Gel permeation chromatography assisted degradation studies indicated polymer stability at physiological pH, while controlled degradation is observed under acidic pH, and the data support the homogeneous distribution of the OTPE monomer throughout the polymer. The hemocompatibility of A-BioHPG is assessed by blood coagulation, platelet activation, red blood cell lysis and aggregation, and cell compatibility with endothelial cells. Our findings show that A-BioHPG is a promising candidate for use in multitude of biomedical applications, including but not limited to solubility enhancement, drug delivery, tissue engineering, and bioconjugation.

A series of polyether and poly(ether carbonate) polyols have been synthesized via Zn(II)-Co(III) double metal cyanide (DMC)-catalyzed ring-opening (co)polymerization of various epoxides, such as propylene oxide, 1,2-epoxybutane, epichlorohydrin, styrene oxide, and glycidol, with and without CO2. The resulting polyether polyols exhibit linear and branched architectures (degrees of branching, DB = 0.27), high catalytic activities with turnover frequencies up to 461 min−1, narrow dispersities (1.15–1.25), and low levels of unsaturation (0.004 meq g−1). The DMC catalysts also enable the efficient synthesis of poly(propylene carbonate) polyol with carbonate contents up to 40% and yields reaching 63%. Additionally, branched poly(ether carbonate) polyols with tunable DB values (0.14–0.21), yields up to 70%, and carbonate contents up to 33% are synthesized via CO2 fixation to glycidol. The synthesized polyols hold strong potential for industrial applications in polyurethanes and other advanced materials, offering versatile performance for use in coatings, adhesives, sealants, and elastomers. Overall, this study highlights the effectiveness of DMC catalysts in producing high-performance polyols, contributing to the development of sustainable materials with precise architectural control.

Chemistry and processes of typical bio-based polyether polyols toward green synthesis: A review.

ABSTRACTUnderstanding the effects of functionality and aromatic content in polyester polyols (Pespols) is critical for optimizing the performance of rigid polyurethane (PUR) foams. In this study, Pespols were synthesized using phthalic anhydride, adipic acid, glycerol, and diethylene glycol in varying ratios to systematically modify their functionality and aromaticity. The polyols were characterized by acid value, hydroxyl value, and viscosity. Their influence on PUR foams was evaluated through cup tests, compressive strength, density measurements, and SEM analysis. Results demonstrated that higher functionality improved mechanical strength, while increased viscosity negatively affected cell morphology. Aromatic‐rich Pespols enhanced compressive properties with minimal effect on cell size. Several of the synthesized formulations exhibited higher compressive strength and similar or lower apparent density compared to commercial Pespol‐based foams. These findings highlighted the importance of balancing viscosity, reactivity, and structural integrity, and indicate that tailored Pespol formulations can serve as viable alternatives to polyether polyols, promoting more cost‐effective and sustainable PUR foam production.

ABSTRACTThe inert nature of carbon fiber (CF) surfaces leads to inadequate bonding strength with resin matrices, thereby constraining the overall performance of its composite materials. Sizing agents are pivotal for enhancing the wettability and interfacial adhesion of CF surfaces. However, most linear‐structured sizing agents fail to fulfill the interfacial performance requirements of composite materials. Inspired by the rhizome structure, a bio‐based hyperbranched waterborne polyurethane sizing agent (WPU‐M) with a hyperbranched structure was synthesized successfully to address this limitation. A key intermediate, polyether–polyester polyol (MEP), was first synthesized via the esterification of L‐malic acid and polyethylene glycol (PEG). The hyperbranched architecture of WPU‐M arises from the multifunctionality of L‐malic acid, which facilitates the formation of a highly branched structure during the polyurethane synthesis. When WPU‐M is applied to carbon fiber/epoxy resin (CF/EP) composites, its distinctive biomimetic rhizome structure significantly enhances its interfacial properties. Compared with the untreated composites, the interfacial shear strength (IFSS) and interlaminar shear strength (ILSS) increased by 71.20% and 39.16%, respectively. The biomimetic rhizome architecture of WPU‐M not only effectively mitigated microscopic defects on the CF surface but also amplified the density of polar functional groups, thereby strengthening the intermolecular interactions between CF and EP. This study presents a novel approach for optimizing the interfacial design of high‐performance carbon fiber composites.