Macromolecular Research最新文献

Zinc gallate (ZnGa₂O₄) has been introduced in various studies as a good host phosphorescent material, and the change of its optical properties by ion doping has received much attention. However, ZnGa₂O₄ is mostly synthesized through solid-state reactions, the reaction conditions of high temperature and pressure were required, and its low dispersibility often limited its applications. In this study, we synthesized normal spinel structured ZnGa₂O₄ nanocrystals through a colloidal method. Lanthanide doping specifically with europium and terbium resulted in red (614 nm, photoluminescence quantum yield (PLQY): 2.2%) and green (545 nm, PLQY: 13.6%) emissions under 254 nm UV excitation. By applying the novel co-doping system of europium and terbium to the synthesis of colloidal ZnGa₂O₄ for the first time, we were able to achieve various color conversions including green, red, and white by adjusting amount and ratio of lanthanide ions.

Graphic Abstract

PL emission spectra by adjusting the ratios of Eu³⁺ and Tb³⁺ doping and the CIE 1931 chromatography diagram of Eu³⁺ and Tb³⁺ co-doping system of ZnGa₂O₄ nanocrystals

Global warming and environmental pollution from fossil fuels have spurred the need for clean energy technologies, among which thermoelectric (TE) devices are promising due to their ability to convert waste heat into electricity. Conducting polymers, particularly poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), have emerged as notable organic TE materials owing to their inherent low thermal conductivity, non-toxicity, and mechanical flexibility. PEDOT:PSS exhibits good stability under high doping level, yielding high electrical conductivity over 1000 S cm⁻¹. This review focuses on the enhancement of the TE performance of PEDOT:PSS through strategies such as post-solvent treatments to selectively remove excess PSS, thereby improving charge carrier mobility and electrical conductivity. Additionally, modifying the interaction between PEDOT and PSS can optimize the macro- and microstructure, leading to improved charge transport properties. The formation of PEDOT:PSS nanocomposites further enhances the Seebeck coefficient and electrical conductivity by enabling effective energy-filtering and improved charge transport pathways. These advancements underscore the potential of PEDOT:PSS in developing efficient, flexible, and stable TE generators for various applications.

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Strategies to improve thermoelectric performance of PEDOT:PSS

In this work, we proposed and synthesized sustainable nanocomposite polyurethane foam (PUF) derived from waste poly(ethylene terephthalate) (PET), reinforced with nano ZnO and incorporating aluminum hydroxide (ATH) as a flame retardant. Chemical structure of oligodiol obtained from the glycolysis of waste PET by diethylene glycol and ZnSO4.7H2O catalyst under microwave irradiation was confirmed by FTIR and 1H-NMR and continuously product of that was used to prepare PUF nanocomposite material. The density of the PUF decreased from 58 to 35 g/cm3 by the addition of ZnO nanoparticles, which are suitable for lightweight and insulation applications. In addition, the incorporation of ATH is indispensable to enhancing the flame retardancy of the PUF nanocomposites with UL-94 (HB) at 100 php ATH loading and UL-94 (VB) V-0 at 150 php ATH loading, simultaneously enhancing the mechanical properties of PUF/ZnO/ATH nanocomposites. The outcomes not only met the fire safety requisites, light-weight, and high mechanical properties for polymer nanocomposite material applications in construction but also incorporated a substantial proportion of discarded PET bottles sourced from associated industries.

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The PUF nanocomposite foam derived from waste PET has high mechanical property and excellent flame-retardant performance to create a sustainable recycling polymer material and improve waste management.

In this study, treated Saccharum munja fibers were considered in particulate (PC), short and random (SRC) and unidirectional (UDC) form along with AW106 Resin and HV953 Hardener as matrix material. Composite laminates were fabricated using a compression moulding machine. Surface treatment of fibers removes dust, lignin and hemicellulose causing better mechanical and free vibration properties. Tensile and flexural tests show the highest value of strength 170 MPa and 143 MPa in the case of UDC composite while the lowest values have been seen in the case of PC. Addition of munja fiber in epoxy matrix enhances the fiber matrix adhesion bonding. The PC composite shows better value of damping than the SRC and UDC composite. The highest natural frequency 43, 233, 298, 849, 918 and 1440 Hz obtained in the case of UDC irrespective of all modes. The highest water absorption rate has been obtained for the SRC while the lowest value was found for PC. Due to the surface treatment of saccharum munja, water absorption properties also improve. The Thermogravimetric shows better stability of UDC. Surface morphology showing the fiber matrix interaction. ANOVA analysis shows that the experimental results output in the case of tensile and flexural tests are significant.

Graphical Abstract

Fabrication of Composite Material

To eliminate the defects of polylactic acid (PLA), maleated polypropylene (MAPP) as a toughener in the presence of a new exchange catalyst, ZnO, was applied. By keeping the amount of MAPP constant, samples with different amounts of ZnO nanoparticles (NPs) were prepared and studied by tensile, Izod, differential scanning calorimetry (DSC), melt flow index (MFI), water droplet contact angle (WDCA), transition electron microscopy (TEM), energy-dispersive X-ray (EDX) and X-ray diffraction (XRD) analyses. In comparison to neat PLA, mechanical tests showed that with a slight decrease in elastic modulus and tensile strength, elongation at break and impact strength values increased more than three times for the sample containing 0.125 wt.% of catalyst. DSC analysis indicated that with the catalyst present, the T_g values of both polymers became closer to one another. Additionally, the absence of cold crystallization in PLA and the reduction in T_m and crystallinity of both polymers are evident factors contributing to the best miscibility of the reactive blend. MFI evaluation displayed decrease in viscosity and WDCA measurement indicated the creation of more polar groups on the surfaces of samples containing ZnO. TEM, EDX and XRD analyses proved the appropriate distribution and dispersion of NPs within the blend matrix as well as obvious decrease in the crystallinity of the resulting alloy. All these results demonstrate the better performance of exchange (esterification and transesterification) reactions between the active groups of both polymers (with ZnO presence) and the formation of PLA–MAPP copolymers, resulting in better miscibility and mechanical properties.

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Possible transesterification reactions during melt blending of PLA and MAPP.

This study investigates the photothermal water evaporation efficiency of Janus-structured sponges prepared from Cu nanoparticles-decorated graphitic carbon nitride/polydimethylsiloxane nanocomposites (CuCN/PDMS) and melamine foam (MF). Photothermal performance evaluation under 1 sun irradiation revealed significant temperature enhancement attributed to the incorporation of carbon nitride (CN) and copper nanoparticles (Cu NPs). Furthermore, the synergistic effect of enhanced light absorption and plasmonic localized heat generation led to remarkable improvements in water evaporation flux and efficiency, particularly evident in the CuCN/PDMS@MF evaporator, which exhibited an efficiency of 84.9%. These findings demonstrate the potential of the devised evaporators for practical applications. Additionally, real-world testing with seawater confirmed sustained functionality and resistance to salt accumulation, further emphasizing the importance of PDMS and MF as key components in the design of efficient Janus evaporators for addressing water scarcity challenges.

Graphical abstract

Janus-structured sponges made from Cu nanoparticles-decorated graphitic carbon nitride/PDMS nanocomposites and melamine foam (CuCN/PDMS@MF) exhibit enhanced light absorption and plasmonic heat generation, significantly improving water evaporation efficiency and offering promising solutions for practical desalination applications

Temporary protective film (TPF) is used as a surface protection for the encapsulation layer during cell cutting and laser lift-off in the manufacturing process of an organic light-emitting diode. TPFs should satisfy the following requirements: good wettability on the surface during the protection step, low peel strength, and clear debonding properties during the removal step. Herein, we used multi-arm-structured trimethylolpropane ethoxylate (TPEG) and linear-structured poly(ethylene glycol) 200 (PEG200) plasticizers to attain these requirements for a polyurethane-based a pressure-sensitive adhesive (PSA). The PSA films with TPEG successfully satisfied the aforementioned requirements. The PSA films with plasticizers exhibited similar wettability and polar surface energy with those of the substrate, thereby demonstrating an interface energy with the substrate of approximately zero. Additionally, the 180° peel strength test showed that the peel strength of the PSA with TPEG was lower than that with PEG200. The observation coincides with small-amplitude oscillatory shear test results obtained via rotational rheology measurements. Furthermore, debonding properties were characterized using time-of-flight secondary ion mass spectrometry (TOF–SIMS) of the adherend surfaces after peeling off the TPFs. The structural properties of TPEG affected migration to a lesser extent than those of PEG200. This is in good agreement with the surface free energies of the adherend surfaces after removing the TPFs. The proposed design strategy can be applied in electronic industry where surface protection using ultra-peelable adhesive films is required.

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This study aimed to address the environmental concerns associated with petrochemical-derived bisphenol-A, commonly used in epoxy resin synthesis, by developing an eco-friendly alternative utilizing bio-based ascorbic acid, or vitamin C. The epoxy compound was synthesized by leveraging the hydroxyl group inherent in ascorbic acid through a reaction with epichlorohydrin. Optimal curing conditions were determined via dynamic scan and isotherm analysis using Differential Scanning Calorimetry (DSC) for the newly synthesized epoxy resin in combination with isophorone diamine (IPDA) as the curing agent. The cured product, obtained under the identified optimal curing conditions, exhibited a soft hardened form with a tensile strength of 7.5 MPa and an elongation of 6%. These findings underscore the feasibility of synthesizing a commercially viable eco-friendly epoxy resin utilizing ascorbic acid, thus contributing to the ongoing pursuit of sustainable material alternatives. The results suggest potential scalability for mass production, emphasizing the significance of this approach in addressing the demand for environmentally friendly materials in various industrial applications.

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Synthesis of ascorbic acid-based epoxy resin.