Macromolecular Research最新文献

Recently, the rapid development of electronic science and technology has led to concerns about electromagnetic pollution, which poses significant risk to human health. However, traditional metal-based electromagnetic interference (EMI) shielding materials are heavy and have poor chemical resistance. Therefore, there is an urgent need to develop lightweight composites that exhibit excellent chemical resistance. Although plastic is generally used in such composite materials, it has contributed to environmental pollution. Therefore, to address the two problems of environmental and electromagnetic pollution, the present study examines the use of the green polymer, polyhydroxy butyrate–co-polylactic acid (PHB–co-PLA), along with carbon black (CB), to prepare composite materials via a simple hot-pressing method. The miscibility of the composite is confirmed via XRD, FT-IR, and SEM analysis. Moreover, the as-fabricated composite materials exhibit improved mechanical properties, electrical conductivity, and EMI shielding effects (SEs) compared to those of the pure PHB–co-PLA. In particular, the composite with 15 wt.% CB exhibits an EMI SE of up to 25.31 dB, thereby shielding 99.70% of the electromagnetic energy. The outstanding performance of these composites gives them tremendous potential for various applications in mitigating electromagnetic interference issues.

Graphical abstract

This study presents a sustainable and lightweight composite based on PHB-co-PLA and carbon black (CB), fabricated via a simple hot-pressing process, as an effective alternative to conventional metal-based EMI shielding materials. The composite demonstrates improved electrical conductivity and EMI shielding effectiveness (up to 25.31 dB at 15 wt% CB), attributed to the conductive network formation and enhanced interfacial compatibility. This environmentally friendly approach offers a practical solution to mitigate both electromagnetic and plastic pollution.

This study aims to synthesize a 4-hydroxybenzaldehyde-functionalized chitosan Schiff base/hydroxyapatite composite (CS-4HBA/HAP) as an advanced polymeric adsorbent. The CS-4HBA/HAP biocomposite was characterized by several techniques: Brunauer–Emmett–Teller (BET) analysis, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and field emission scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (FESEM–EDX). The adsorption performance of CS-4HBA/HAP on cationic dye (basic red 2, BR2) removal was investigated. The results showed that CS-4HBA/HAP had a BET surface area of 13.71 m²/g, an average pore width of 10.07 nm, and a total pore volume of 0.03455 cm³/g. With an average crystallite size of 15.18 nm, the CS-4HBA/HAP mostly displays polycrystalline characteristics. The Box–Behnken design (BBD) was employed to optimize the adsorption process parameters, which included the CS-4HBA/HAP dose (0.01–0.09 g), pH (4–10), and adsorption time (10–40 min). The adsorption kinetics complied with the pseudo-first-order (PFO), and the adsorption isotherms complied with the Freundlich model. The adsorption capability of CS-4HBA/HAP biocomposite was determined to be 237.62 mg/g, with the dye adsorption mechanism being due to a wide variety of interactions, including electrostatic, n–π, hydrogen bonding, Lewis acid–base interaction, and π–π interactions. This study introduces the Schiff base-CS-4HBA/HAP composite as an effective adsorbent for removing BR2 dye, indicating its applicability in cationic dye removal.

Graphical Abstract

Sequential solution doping is one of the most frequently used methods for doping conjugated polymer films. Since the spatial distribution of dopants in doped polymer films significantly influences their electrical properties, elucidating how various material parameters affect the dopant distribution in sequentially solution-doped polymer films is of great importance. This study investigates the effect of crystallinity in conjugated polymer thin films on the spatial distribution of dopants along the out-of-plane direction. The results show that higher crystallinity in polymer films leads to a more non-uniform dopant distribution, with a greater composition of dopants at the film surface compared to the bulk. This phenomenon is attributed to the crystallinity-dependent swellability of polymer films, where films with higher crystallinity exhibit lower swellability, resulting in less efficient dopant diffusion from the surface to the bulk compared to films with lower crystallinity.

Graphic abstract

This study explores how crystallinity in conjugated polymer thin films affects dopant distribution during sequential solution doping, revealing that higher crystallinity results in a more nonuniform distribution, with greater dopant compositions at the surface than in the bulk. This is due to lower swellability, which limits effective dopant diffusion from the surface to the bulk.

The exponential rise of 3D printing in the recent years has revolutionized the manufacturing and production industry in more than one way. Advancement in 3D-printing technologies has also led to an enhancement in a component’s strength, stiffness, and weight. Among other widely used materials, polymers such as Polylactic Acid + (PLA +) which is an enhanced version of the conventional PLA offers several advantages, such as affordability, sustainability, and ease of use. An important parameter in determining the mechanical properties of 3D-printed components is infill density. Infill density is the amount of an object’s inner volume that is filled by the material. This research paper aims to evaluate the relation between infill density and structural integrity of the component. Using 3D printer, samples with infill densities of 25%, 50%, and 100% were fabricated and subjected to standardized tensile testing. Additionally, Field Emission Scanning Electron Microscopy (FESEM) was used to view the fracture surfaces at a microscopic scale and it provided valuable insights into the fracture behavior of the components. The study confirms that both infill density and pattern significantly influence the mechanical properties of 3D-printed parts. The results reveal that upon increasing infill density from 25 to 100%, a 168% increase in tensile strength and 20.34% reduction in percentage of elongation are observed. By gaining a proper understanding of the relation between infill density and structural integrity, 3D-printed components can be used in practical day-to-day applications, and also, by understanding how internal geometry influences material failure, it can be useful in devising techniques that can contribute to more efficient additive manufacturing processes.

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A series of self-healing polyurethane (PU) polymers were synthesized via the Diels–Alder reaction between the furan-functionalized PU prepolymer and bismaleimide (BMI). The PU prepolymer is a reaction product of polyethylene glycol (PEG) and a pentamethylene diisocyanate trimer (PDI-t). Furfuryl amine was attached to the terminal isocyanic groups of PU, resulting in furfuryl amine polyurethane (PU-FA). PU-FA was cross-linked via dynamic bonds between the furan groups and BMI, generating reversible bonds with the material. This study explored reversible polymer networks under various thermal conditions, including different reaction parameters, prepolymer ratios, and healing temperatures, to evaluate the healing capabilities of these polymers. The results demonstrated that PU-DA exhibits thermal reversibility, as evidenced by the appearance of an endothermic peak in the DSC analysis, indicating bond cleavage via the retro-Diels–Alder (r-DA) reaction. This endothermic peak re-emerged after cooling at 70 °C for 24 h, further confirming the reversibility of the reaction. Additionally, crack healing in the PU-DA film was facilitated by the synergistic effects of the thermally reversible Diels–Alder reaction and the thermal mobility of molecular chains. The self-healing performance evaluation revealed that PU-DA samples with an NCO/OH ratio of 1.5 exhibited a reduction in tensile strength after healing compared to the original PU-DA specimens before heat treatment. Conversely, samples with an NCO/OH ratio of 3 demonstrated a healing efficiency exceeding 100%, attributed to the enhanced cross-link density, which contributed to a more robust network structure.

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In this study, self-healing Diels-Alder polyurethane (PU-DA) was successfully synthesized using PDI trimer. The findings confirmed that the material's healing mechanism is activated by the reversible interaction between furan and maleimide groups within PU-DA, enabling it to autonomously repair structural damage

In this study, the structural, dielectric, conductive, and relaxation behavior of neat epoxy (NE) and its composites containing 1 wt.% of various metal oxides (ZnO, TiO₂, Al₂O₃, SiO₂) combined with multi-walled carbon nanotubes (MWCNTs) were investigated. While previous studies have explored nanofiller-doped epoxy systems, they often lacked a detailed understanding of interfacial interactions, dielectric relaxation mechanisms, and predictive modeling for dielectric properties. To address this gap, XRD analysis was performed to confirm the crystalline phases of ZnO, TiO₂, and Al₂O₃, the amorphous nature of SiO₂, and the successful incorporation of MWCNTs into the composites. The dielectric constant (ε′) was measured, revealing the highest value for neat epoxy doped with 1 wt.% of (ZnO + MWCNT). Dielectric loss (ε′′) and electrical modulus analysis were conducted to gain a deeper understanding of relaxation behavior in respective composites. The findings demonstrate the critical role of nanoparticle properties and their synergistic interactions with MWCNTs in tailoring the structural and functional properties of epoxy-based composites. Furthermore, this study evaluates the predictive performance of XGBoost, Extra Trees, and Gradient Boosting regression models for dielectric properties (ε′ and ε′′) across intermediate frequencies, with Extra Trees achieving the best results (R² = 0.9999 for ε′ and R² = 1.0000 for ε′′). These findings contribute to the advancement of epoxy-based materials with tuneable electrical properties, making them promising for future electronics and energy storage. Integrating experimental data with machine learning can further enhance composite design for industrial applications, ensuring optimized performance and reliability.

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Chitosan of various molecular weights are known to have biocompatibility, angiogenic, antimicrobial, and in vitro anti-inflammatory effects. However, the intricacies of wound healing using hydrogel formulations in vivo require further investigation. In this study, high-molecular-weight chitosan (HMWC) was sequentially treated with immobilized chitosanase to synthesize active molecular chitosan (AMC). The antimicrobial activity and wound-healing effect of AMC-based hydrogels were evaluated. Two types of AMC-based hydrogel, namely AMC-based hydrogel-h (AMC-h) from the hydrolysis of HMWC and AMC-based hydrogel-w (AMC-w) from water-soluble chitosan, were investigated for efficacy against methicillin-resistant Staphylococcus aureus (MRSA) and in vivo wound healing. Subsequently, 48 full-thickness wounds were created in the BALB/c nude mice. The wounds were treated with AMC-h, AMC-w, or phosphate-buffered saline as controls. Collagen synthesis and the production of VEGF and TGF-β were quantified using ELISA and immunohistochemistry. AMC-h treatment significantly reduced the unhealed wound areas and displayed potent antimicrobial activity. It also promoted higher collagen synthesis and more substantial wound contraction than AMC-w. Taken together, our results demonstrate that AMC-h has the potential to accelerate wound healing using hydrogel formulations by enhancing antimicrobial activity, collagen synthesis, and wound contraction.

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Herein, an ionically cross-linked chitosan-oxalate/Al₂O₃ (CHS-OXA/Al₂O₃) mesoporous nanocomposite was prepared by modifying the natural macromolecular biopolymer (chitosan, CHS) with a metal oxide nanomaterial (aluminum oxide, Al₂O₃ nanoparticles) and then using an ionic cross-linking method with oxalate (OXA). The physicochemical properties of CHS-OXA/Al₂O₃ have been comprehensively analyzed using methods like FTIR, XRD, BET, pH_pzc, and FESEM-EDX. Box–Behnken design (BBD) was adopted to analyze the efficacy of CHS-OXA/Al₂O₃ in eliminating eosin y (EOY) dye from an aqueous solution. The study included many aspects that influence the adsorption process, including the quantity of CHS-OXA/Al₂O₃ (ranging from 0.01 to 0.07 g), the duration of the process (10–40 min), and the pH level (ranging from 4 to 10). The highest EOY decolorization (98.4%) was attained at a pH of 4, a dosage of 0.053 g CHS-OXA/Al₂O₃, and a removal time of 39.6 min. The equilibrium behavior of EOY on CHS-OXA/Al₂O₃ matched well with the Freundlich isotherm. The kinetics data of EOY adsorption by CHS-OXA/Al₂O₃ were well characterized using a pseudo-first-order model. The computed enthalpy ΔH° was endothermic (13.04 kJ/mol), the entropy ΔS° was positive (0.066 kJ/molK), and Gibb's free energy ΔG° was negative (6.83–8.85 kJ/mol) according to the thermodynamic studies, confirming that the adsorption process is spontaneous. The CHS-OXA/Al₂O₃ material possesses an adsorption ability of 378.6 mg/g. This work showcases the outstanding capacity of CHS-OXA/Al₂O₃ as a very effective adsorbent for eliminating synthetic dyes from wastewater.

Graphical abstract

A chitosan-based nanocomposite of ionically crosslinked chitosan-oxalate/Al₂O₃ nanoparticles was synthesized. The chitosan-based nanocomposite exhibited high efficiency in removing eosin Y dye from water. Adsorption mechanisms included electrostatic attraction, hydrogen bonding, and n-π interactions

MXenes, two-dimensional (2D) metal carbides, and nitrides exhibit exceptional electrical conductivity, hydrophilicity, and tunable surface properties, making them highly attractive for applications in energy storage, catalysis, and sensing. However, MXenes (e.g., Ti₃C₂T_x) suffer from mechanical brittleness and poor oxidation stability, limiting their applicability and long-term durability. In this study, we present a composite integrating MXene with TEMPO-oxidized cellulose nanofibers (TOCN) derived from tunicate and tannic acid (TA). TOCN possesses high mechanical strength due to the high crystallinity of tunicate, while carboxyl groups introduced by TEMPO-mediated oxidation facilitate improved interfacial bonding with MXene layers. TA, a natural polyphenol with excellent oxidation resistance, further integrates MXene and TOCN by strong hydrogen bonding. The fabricated MXene/TA/TOCN composite demonstrated significantly improved mechanical strength of 98.3 MPa and oxidation resistance while maintaining good electrical conductivity (81.4 S/cm). This synergistic integration of TA and TOCN highlights the potential of MXene/TA/TOCN for energy storage devices and flexible electronic applications.

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We integrated tannic acid (TA) and TEMPO-oxidized cellulose nanofibers (TOCN) with MXene to overcome its inherent poor oxidative stability and durability. The resulting MXene/TA/TOCN composite demonstrated enhanced stability in an acidic solution and under ultrasonication, highlighting our approach to address its critical limitations

New phenolic organic salt crystals exhibiting large macroscopic second-order optical nonlinearities have been developed. Two molecular anions, 4-bromobenzenesulfonate (BBS) and naphthalene-2-sulfonate (N2S), were incorporated with highly efficient nonlinear optical 2-(4-hydroxy-3-methylstyryl)-1-methylquinolinium (OMQ) cationic chromophores into crystals. Both OMQ-BBS and OMQ-N2S crystals demonstrated second harmonic generation, which confirms their non-centrosymmetric molecular arrangement. Particularly, the OMQ-BBS crystals possess a non-centrosymmetric space group symmetry Cc with a high-order parameter due to a small molecular ordering angle of approximately 21°, resulting in a very large macroscopic second-order nonlinear optical susceptibility, with the effective first hyperpolarizability of about 105 × 10^–30 esu. Furthermore, the non-centrosymmetric crystal phase of the OMQ-BBS crystals exhibits remarkable thermal stability up to its melting temperature of 304 °C.

Graphical abstract

Newly designed phenolic organic styryl salt crystal, 2-(4-hydroxy-3-methylstyryl)-1-methylquinolinium 4-bromobenzenesulfonate (OMQ-BBS), exhibits a large macroscopic second-order nonlinear optical susceptibility (105 × 10^-30 esu).