Journal of Polymer Research最新文献

In this study, a new chiral polymer incorporating cinchonine- and cinchonidine-based squaramide units in its main chain has been successfully synthesized and evaluated as asymmetric organocatalysts. The novelty of this work lies in the integration of dual cinchonine- and cinchonidine cinchona moieties within the squaramide framework, offering enhanced chiral environments and hydrogen-bonding capabilities for asymmetric catalysis. Cinchonine- and cinchonidine-based chiral squaramide monomers bearing olefinic double bonds were first designed and synthesized, followed by the Mizoroki–Heck coupling polymerization reaction using various diiodo linkers to yield the desired polymers with controlled microenvironment. The resulting polymeric catalysts exhibited remarkable catalytic activity (upto 99% yield) and enantioselectivity (upto 94% ee, 75:1 dr) in model asymmetric reactions, demonstrating the significant role of the cinchonine- and cinchonidine cinchona-derived units and solvent polarity on the reaction outcome. Importantly, due to their insolubility in common organic solvents, the polymeric catalysts could be easily recovered and reused multiple times without noticeable loss of performance. These findings establish a new strategy for developing recyclable chiral polymeric catalysts based on cinchonine- and cinchonidine cinchona–squaramide frameworks, combining high catalytic efficiency, robust stability, and excellent reusability for sustainable asymmetric synthesis.

The widespread use of zinc oxide (ZnO) as an activator in sulfur vulcanization raises environmental concerns due to the potential release of zinc species from rubber products. In this study, strategies to reduce ZnO content in natural rubber (NR) compounds were investigated by employing different ZnO systems and mixing techniques. Conventional white seal ZnO (ZnO_ws), active nano-ZnO (ZnO_a), and ZnO-coated calcium carbonate (ZnO-CaCO₃) were incorporated into NR compounds and processed using conventional (melt) mixing and masterbatch (latex) mixing. The influence of ZnO type and mixing technique on ZnO dispersion, vulcanization behavior, crosslink density, mechanical performance, and thermal aging resistance was systematically evaluated. SEM observations confirmed that masterbatch mixing produced finer and more homogeneous dispersion of ZnO within the NR matrix compared with conventional mixing, resulting in accelerated vulcanization and enhanced mechanical properties. Among the ZnO systems studied, ZnO-CaCO₃ exhibited the most favorable overall performance, including fast curing, high mechanical strength, and improved thermal aging resistance. Notably, ZnO-CaCO₃ contains only about 60% ZnO, enabling an approximate 40% reduction in effective ZnO content relative to commercial ZnO_ws while maintaining vulcanization efficiency. The findings demonstrate that ZnO-CaCO₃, particularly when combined with masterbatch mixing, represents a promising approach for developing environmentally friendly NR vulcanizates with high performance.

Perfluorosulphonate Nafion cation exchange ionomer membrane (du Pont de Nemours and Co) is a sulfonated tetrafluoroethylene-based fluoropolymer-copolymer with ion rich clusters arranged in a reversed micelle structure. The permselective nature of membrane allows separation and is affected by various experimental parameters (pH, solution composition). Pretreatment of Nafion using a prescribed method (developed by DuPont) was essential prior to its use. Selective separation is generally achieved by using masking agents to reduce interferences. Therefore, it became crucial to understand the effects of both pretreatment protocols and presence of complexing agents. Orthophenanthroline was used as a complexing ligand both in solution as well as loaded within the pretreated membranes. Water sorption of pretreated membranes incorporated with metal ions, ligands and metal–ligand complex has been studied. The water sorption of the pretreated impregnated membrane follows the order metal ions > metal – Oph > Oph. The use of various models (Peleg, pseudo first order and pseudo second order) showed that the water uptake is physisorption in nature. The water molecules are present in a single layer bound to the surface as water of hydration of the cations. The initial rate of sorption is found to be highest for hot acid pretreated Nafion. The presence of orthophenanthroline in solution showed a greater decrease in Cu uptake as compared to Zn. However, impregnation of the ligand within the membrane showed a preferential uptake of Cu. Both the observations could be attributed to the stronger complexation of Cu with ligand. Kinetic and mechanism modelling of data indicates that metal ion uptake is chemisorption in nature and follows both intraparticle and film diffusion mechanisms. Simulated binary mixtures of Cu and Zn in different ratios were used for separation using the impregnated membranes. It was seen that a preferential uptake of Cu was achieved. Under the conditions of study (pH = 5), the ligand was not leached out of the membranes. The removal of ligand and its metal complex could be achieved using 0.1 M acid. UV Visible spectroscopy of loaded membranes confirmed the change in water cluster as well as the presence of both orthophenanthroline and its metal ion complex within the water clusters. The difference in spectra of copper complexes in solution and membrane confirm the presence of disparate structures in membrane phase (probable dimer formation). DFT calculations carried out to understand the process reveal that Cu can form both 1:1 and 1:2 complexes to nearly same extent while Zn preferably forms the 1:2 complex. The binding energy values of the 1:2 metal complexes (Cu 44.8 kcal/mol and Zn 32.1 kcal/mol) indicate Cu forms a stronger complex as compared to Zn.

A method for synthesizing copper nanoparticles (CuNPs) immobilized on astralenes (Astr) or silicon dioxide (SiO₂), using ascorbic acid or formalin as reducing agents, is presented. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses demonstrate that the CuNPs/Astr system reduced with ascorbic acid yields homogeneous, nearly spherical nanoparticles with an average size of ~ 59 nm, a narrow size distribution, and minimal agglomeration. Opposite, the use of formalin results in irregular, elongated particles (up to 800 nm) and partial oxidation to Cu₂O/CuO. CuNPs on SiO₂ exhibit larger particle sizes (103–112 nm) and show reduced sensitivity to the reducing agent, likely due to spatial confinement within the porous matrix. Scherrer analysis confirms the smallest crystallites (34 nm) for the ascorbic acid – reduced CuNPs/Astr system. Incorporation of CuNPs/Astr into an acrylate matrix at a concentration of 0.05 wt% moderately decreases the photopolymerization rate (maximum rate ~ 6%/s compared to ~ 13%/s for the neat system) without affecting the monomer conversion, thereby potentially reducing internal stresses. The composite exhibits a decrease in ultraviolet (300–450 nm) transmittance while maintaining high transparency (> 89%) in the visible and near-infrared regions. This behavior is attributed to the combined effect of surface-oxidized copper particles and the π-conjugated Astr framework. Optical microscopy confirms uniform nanoparticles distribution without visible agglomeration. Thermal analysis reveals delayed thermal degradation with no significant change in the glass transition temperature. Overall, the CuNPs/Astr system synthesized using ascorbic acid represents an efficient transparent nanofiller for UV-filtering optical coatings and optoelectronic components.

While valued for their mechanical properties, conventional polyurethane elastomers lack self-healing capabilities, leading to irreversible damage and limited-service life. To address this, in this study, we designed and synthesized a novel intrinsic self-healing polyurethane elastomer by integrating a dual dynamic network comprising multiple hydrogen bonds and nitrogen-coordinated boroxane rings. This system was constructed via the stepwise polycondensation of polytetrahydrofuranediol (PTMEG-2000), isophorone diisocyanate (IPDI), 4,4′-methylenebis(2-chloroaniline) (MOCA), 2-formylphenylboronic acid (FBA), and 2,6-pyridinediol (PDM). The resulting elastomer exhibited significant strain-induced strengthening and efficient autonomous healing at room temperature (25 °C). Specifically, at an optimal PDM/MOCA molar ratio of 60/40 (PU_HB-60/40), the material achieved a tensile strength of 18.8 MPa with a healing efficiency of 94.7%, elongation at break of 2132% (91.7% recovery), and toughness of 117.0 MJ/m³ (86.7% recovery). The dynamic reversible bonds enabled repeated self-healing at the same fracture site. Furthermore, the material demonstrated excellent recyclability; where after dissolution and reprocessing, its mechanical properties remained largely intact. This study presented a viable molecular strategy for fabricating robust, self-healing, and recyclable elastomers that operate under ambient conditions, offering broad potential for sustainable material applications.

Polypropylene (PP) composites reinforced with talc microparticles is one of the most widespread polymer composite materials. However, its thermal, mechanical and fracture behavior under different conditions is not explored more. In order to design better PP/talc structures and predict their failure in the context of its aging and degradation. The present work investigates the influence of thermal ageing (60 °C for 3–14 days), water immersion (distilled and seawater, 30 days), and ultraviolet exposure (30 days) on the mechanical and thermal properties of PP/talc microcomposites containing 50 wt% talc. Tensile tests reveal a reduction in ultimate strength from 40 MPa (unaged) to 35 MPa after thermal ageing and to 20 MPa following UV exposure, the latter corresponding to a 50% loss together with a decrease in ultimate strain from 0.13 to 0.05. Water ageing induces a 28% decrease in tensile strength. Vickers hardness decreases from 4.69 MPa to 3.23 MPa under UV ageing. DSC and TGA analyses confirm that UV radiation causes the most pronounced thermal degradation, lowering the onset degradation temperature from 510 °C to 455 °C, whereas thermal ageing produces less effects than UV radiations. These findings provide insight into the durability of PP/talc composites under various service environments.

Polyphenylene sulfide(PPS) has excellent high temperature resistance, corrosion resistance, and high strength performance, but its wear resistance is relatively poor. Mo₂CT_x is a self-lubricating and wear-resistant MXene material. In this study, PPS nanocomposites with different mass fractions of surface modified Mo₂CT_x were prepared by micro injection molding, and their thermal stability, tribological properties at high temperature, and enhancement mechanism were investigated. The results showed that compared with pure PPS, the thermal properties of the nanocomposite were significantly improved, and the friction coefficient and wear volume were reduced at both room temperature and high temperature. Thermal analysis shows that the degradation temperature (Td05) and crystallinity of PPS nanocomposites are significantly increased, which is due to the enhanced interfacial bonding strength of the composite by polydopamine. During the friction process, the addition of Mo₂CT_x is beneficial for the formation of lubrication transfer films and the transformation of wear mechanisms (abrasive wear and adhesive wear), which helps to improve tribological behavior. When the MXene content is 1.0%, a wear rate reduction of 94.4% and 92% was achieved at room temperature and 250 °C, respectively. This work provides a feasible solution to improve the performance of PPS under extreme conditions.

This study evaluates the potential of potato peel waste (PW) as a sustainable raw material to create biodegradable films. By incorporating sodium alginate (SA) at 10%, 20%, and 30% ratios, and calcium chloride (CaCl₂) as a crosslinking agent, the research aims to address the limitations of PW films, particularly their poor mechanical and moisture barrier properties. The results revealed a 69% increase in tensile strength and a 76% enhancement in elongation at break for crosslinked 20% SA films compared to pure PW films. Non-crosslinked 20% SA films, while having slightly lower mechanical properties, exhibited a 112% increase in elongation at break, offering improved flexibility for certain applications. Water vapor permeability (WVP) was reduced by 30%, from 2.4 × 10⁻12 g/(Pa·cm·s) in the PW film to 1.6 × 10⁻12 g/(Pa·cm·s) in the crosslinked 30% SA formulation. These improvements in both mechanical strength and moisture resistance highlight the potential of PW-based films as a viable, sustainable alternative for packaging applications. This research offers a promising solution for repurposing potato peel waste, reducing reliance on petroleum-based products, and addressing agricultural waste environmental challenges.

In order to study the strength characteristics of carbon-glass hybrid fiber reinforced composite wind turbine blades under extreme conditions. This study adopts a combination of finite element simulation and experimental methods, taking 1.5 MW wind turbine blades as the object, selecting reinforcement materials with carbon/glass fiber mixing ratios of 2:6, 4:4, and 6:2, exploring the strength response of blades under the coupling of temperature-mixing ratio-wind speed, and analyze the effects of temperature and wind speed on blade fatigue life. The results showed that at a temperature of 45 ℃, 25 ℃, and -35℃, the tensile strength of the mixed blade specimen is 44.7%, 41.5%, and 33.5% higher than that of the glass fiber sample, respectively. At a wind speed of 12 m/s and 25℃, the maximum stress of the blade decreases with the increase of carbon fiber(19.9 ~ 44 MPa); At a wind speed of 30 m/s and 25℃, the maximum stress of each type of blade (199 ~ 283 MPa) did not exceed the specimen tensile strength (351 ~ 515 MPa); At -35 ℃ and rated wind speed, the maximum stress of the blade significantly increased (286 ~ 384 MPa). At -35 ℃ and a wind speed of 30 m/s, the root of the blade is the key area of stress concentration, and the maximum stress increase to 584 MPa. Extreme wind speed and -35 ℃ low temperature respectively reduced the fatigue life of the blades by 92.6% and 97.8% compared to the rated working conditions. This study provides key technical support for the selection, and life prediction of blades in extreme environments.

For sustainable and eco-friendly packaging of various photodegradable compounds (dyes, pigments, phenols, etc.), there is a necessity to develop green packaging material. In this study, the chitosan was reinforced with laponite and polydopamine (PDA) to enhance its thermomechanical properties for UV–shielding application. Chitosan solution (S₁) showed increased hydrogen–bonds as pH of the solution increased from 4 (G’ = 0.6 Pa) to 12 (G’ = 5.1 × 10⁴ Pa) due to deprotonation of –NH₃⁺ to –NH₂ group. A slight decrease in the G’ of chitosan–PDA (S₃) was observed at all pH values. The addition of laponite to S₁ (S₂) showed maximum G′ (1.6 × 10⁵ Pa) at pH 10 probably due to increased electrostatic interactions between laponite and chitosan. The cumulative effect of hydrogen-bonding and electrostatic interactions led to maximum G′ (1.8 × 10⁵ Pa) in laponite–PDA–chitosan (S₄) at pH 8. Consequently, S₁–S₄ at pH 8 were casted into films A–D, respectively and studied using various characterization techniques. Film C showed lower swelling (896.7 ± 30.4%) and higher contact angle (55.1 ± 0.8˚) as compared to Film A. Further, the incorporation of laponite to the films, Film B and Film D, exhibited a more significant decrease in swelling (151.9 ± 13.8% and 100.2 ± 10.4%, respectively) and increase in contact angle (63 ± 0.9˚ and 66.5 ± 1.3˚, respectively). Moreover, the degradation of Rhodamine B (RhB) over a period of 240 min in the presence of films was evaluated to assess the UV shielding properties of the films. It was observed that film D showed lowest RhB degradation (19.6%) as compared to unshielded RhB (70.03%).