Macromolecular Research最新文献

The objective of this study is to investigate the effects of incorporating negatively charged core–shell type SiOx/PS (silicate core/polystyrene shell) nanoparticles on the mechanical, thermal, and rheological properties of a non-commercial thermoplastic polyurethane (TPU, pristine 9094) film. TPU-SiOx/PS nanocomposites were fabricated by blending pristine 9094 TPU-based resin with SiOx/PS nanoparticles of 1, 2, and 3 wt% loading and prepared as sheet-type films via T-die extrusion. The dispersion of SiOx/PS nanoparticles within the TPU matrix was confirmed using FTIR (Fourier-Transform Infrared Spectroscopy) and zeta potential (ζ) analysis. Results showed peaks assigned to benzene ring (698 cm⁻¹, 1638 cm⁻¹) in the polystyrene structure, with a shift in zeta potential (ζ) from + 19.77 mV (pristine) to −13.30 mV (1 wt%) and −6.42 mV (2 wt%). At 2 wt%, the SiOx/PS-TPU film exhibited an increase of 13.2% in yield strength and 20.1% in Young’s modulus compared to pristine 9094 film. This loading also yielded the highest increases in storage modulus (G′) and complex viscosity (η). The decrease in the slope of G′ from G′ ~ ω^1.67 (pristine 9094) to G′ ~ ω^1.62 (2wt%) reflects the reinforcement of polymer chains and enhanced elasticity. Increases in T_g,SS (glass transition temperature of soft segment) and decreases in T_g,HS (glass transition temperature of hard segment) suggest enhanced interactions between SiOx/PS nanoparticles and polymer chains. Finally, a 2 wt% loading enables the mechanical and rheological properties of the pristine 9094 TPU film comparable to those of the commercial pristine 49,510 TPU film.

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TPU-nanocomposite film through T-die extrusion process

This study introduces the possibility of using polyaniline as a thermally conductive filler in the manufacturing process of composites using epoxy. Compared to conventional thermally conductive fillers, polyaniline is a material with a simple synthesis process and is cost-effective. In this experiment, among various types of polyaniline, polyaniline in the form of an emeraldine salt (ES) doped with protons and polyaniline in the form of a dedoped neutral emeraldine base (EB) were used as the thermally conductive filler. ES doped with protons show higher electrical and thermal conductivity than EB due to the conductive polymer characteristics in which the thermal conductivity increases as the electrical conductivity increases. We put both fillers into the widely commercially available diglycidyl ether of bisphenol A (DGEBA) epoxy composite, and analyzed the effect of the thermal conductivity of the filler increased by doping on the thermal conductivity of the composite, and analyzed the possibility of use as a thermally conductive filler. The epoxy resin without filler was measured to have the thermal conductivity of 0.21 W/m K, the thermal conductivity of the composite reinforced with EB filler was measured to be 0.27 W/m K, and the thermal conductivity of the composite reinforced with ES filler was measured to be 0.29 W/m K. The results confirmed that the input of polyaniline as a thermally conductive filler could improve the thermal conductivity of the composite, and also confirmed that the proton-doped ES filler showed higher thermal conductivity than the neutral EB filler. Through this study, we highlight the possibility that polyaniline can be used as a promising thermally conductive filler for various composite materials.

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Proton-doped polyanilines, when used as thermally conductive fillers in epoxy composites, increase thermal conductivity more effectively than dedoped polyanilines

High energy radiation processing has proven to be remarkably effective in enhancing the properties of polymeric materials. Specially, electron beam (E-beam) radiation stands out as a versatile technique for crosslinking, compatibilizing, and grafting polymer blends and composites. Its reputation for simplicity, high speed, environmental friendliness, and user-friendliness has made it the preferred method in industries such as automotive, electrical insulation, ink curing, surface modification, food packaging, medical sterilization, and healthcare. This review focuses on recent advancements in the application of E-beam irradiation to ethylene vinyl acetate (EVA) blends and composites, with a specific focus on incorporating partially nanoscale clay to achieve desired properties and the controlled crosslinking of blends and nanocomposites using high-energy radiation. Numerous studies have investigated the development and modification of EVA with various thermoplastic and elastomeric polymers, highlighting radiation-induced grafting of different monomers onto the polymer backbone. The review primarily examines the utilization of EVA blends and composites for the purpose of adjusting their physical, chemical, thermal, surface, and structural properties. Additionally, it investigates the formation of crosslinking by analyzing gel content and optimizing the dosage of crosslinking co-agents and fillers. Furthermore, the study explores the effect of E-beam irradiation on the tensile properties, specifically the enhancement of tensile strength resulting from crosslinking formation at varying E-beam radiation doses. Additionally, the diverse applications of high-energy radiation-modified polymers in industries such as automotive, wire and cable insulation, heat shrinkable tubes, sterilization, biomedical, nuclear, and space industries are discussed. These applications demonstrate the extensive potential and practicality of utilizing high-energy radiation processing to enhance the properties of polymeric materials in various industrial settings.

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Effects of electron beam irradiation on ethylene vinyl acetate blends and composites.

This study examines the multiscale acoustic properties of sound-absorbing polyurethane (PU) foam impregnated with graphene oxide (GO). GO impregnation into the PU foam was achieved through a vacuum-assisted process. The effects of GO impregnation on the macroscopic acoustic behavior, transport parameters, and sound absorption coefficients were investigated. Scanning electron microscopy images revealed that the impregnated GO enveloped the open pores within the porous structure. Geometric parameters derived from the microstructural observations were used to perform acoustic simulations. Models with partially open cells could be used to accurately predict the transport parameters and sound absorption coefficients of foams with low levels of GO impregnation. For foams with high levels of GO impregnation, it was necessary to incorporate closed cells into the model, which significantly enhanced the prediction accuracy for the transport parameters and sound absorption coefficients. This study advances our understanding of the acoustic properties of GO-impregnated PU foams and will be beneficial for developing more effective sound-absorbing materials.

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Acoustical characterization of graphene oxide impregnated polyurethane foam

The amine sensing is of critical importance in food safety, environmental protection, and national security. We herein report our novel approach to amine detection based on swelling parameters and strain sensors. Specifically, we prepared strain sensors using poly(3-hexylthiophene) (P3HT), single-walled carbon nanotube (CNT), and polydimethylsiloxane (PDMS). P3HT-wrapped CNTs were produced in chloroform, and this solution was drop-casted onto PDMS pads, followed by attaching copper electrodes, resulting in CNT/PDMS strain sensors. It has been well documented that PDMS possesses matching solubility parameters with diisopropylamine, and we discovered that diisopropylamine caused the most significant swelling of the PDMS pad compared to the other seven solvents/chemicals used in this study. The swelling of PDMS induced by diisopropylamine resulted in a large increase in electrical resistance (R/R₀ ~ 2.21, wherein R and R₀ represent the resistances before and after swelling, respectively), probably due to the transmitted stress/strain from PDMS swelling and thus the perturbation of the CNT networks. This study offers a new method for fabricating chemical sensors utilizing strain based on polymer swelling.

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The swelling of PDMS induced by various solvents/chemicals was recorded as changes in resistivity, leading to the fabrication of strain-based chemical sensors.

When wounds are caused by burns, traumatic injuries, chronic ulcers, or diabetic injuries, bacterial infection can be a major problem. It can even be life-threatening. The wound-healing process is slowed by multidrug-resistant microorganisms, so antimicrobial wound dressings are generally used. Nanostructures comprise nanoparticles, nanorods, nanospheres, nanoshells, nanoflowers, hybrid polymers, etc., which can be used for wound healing or can be used to deliver the drug at the site of the wound to improve the drug’s efficacy and stability. In this review, we shall discuss the different therapeutic strategies of nanoparticle-based wound dressing materials with or without the incorporation of natural products. The recent research on nanostructure-based wound dressing materials will also be discussed.

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Combination of natural products and nanostructures assist wound healing

Halide perovskites demonstrate excellent optoelectronic characteristics such as large light absorption coefficients, long charge carrier diffusion lengths, and high charge carrier mobility. With these benefits, halide perovskites have been considered as a next-generation photoactive materials and introduced to diverse optoelectronic devices. Among them, perovskite solar cells (PSCs) and photodetectors (PPDs) have been paid attention, which have in common that they transform the light signals into photocurrent. In particular, great innovations have been achieved in improving the performance of PSCs and PPDs. With this regard, in this perspective, we have explained the development and recent progress in PSCs and PPDs. In addition, future research directions have also been outlined.

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This perspective summarizes the recent advances in halide perovskites for optoelectronic devices including solar cells and photodetectors and provides the guideline for further research direction in the field.

In this study, it is aimed to provide new functions to polymers by producing polymer blends. Two important biopolymers, PLA as the main matrix and PEG polymers were mixed in different ratios to produce shape memory (SM) PLA-PEG blend by solution method. The characteristic -C = O stretching vibration of PLA was observed as a strong signal in the ATR-FTIR spectra of the polymer blends. According to the heat flux versus temperature measurement results of PLA-PEG blends, characteristic peaks of each polymer were observed with increasing temperature. This result indicates that the polymer blends are immiscible. The thermal stability of the PLA-PEG blend was determined by thermogravimetric measurements and it was observed that the mass loss in the blend decreased with increasing PEG ratio. Since PEG and PLA are bicrystalline polymers, crystal structures of both polymers were found in X-ray measurements in the shape memory polymer blends produced. Finally, it was found that the produced PLA-PEG blend showed shape memory property and the blend could return to its original shape in as short as 8 sec.

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High-molecular-weight ABA triblock copolymers (PLA–PEs–PLA), consisting of poly-l-lactide (PLLA: A) and two types of polyethers (PEs: B), i.e., poly(oxyethylene) (PEG: polyethylene glycol) and Pluronic^® [PN: poly(oxyethylene)-b-poly(oxypropylene)-b-poly(oxyethylene)], were synthesized by ring-opening polymerization of l-lactide by using bis-hydroxyl-terminated PEs as macroinitiators. Polymer films of these block copolymers were fabricated by the conventional hot-pressing method and uniaxially cold drawn to five times at 80 °C. Evaluation of the mechanical properties of these films revealed that the drawn films can retain high strength (ca. 100 MPa) and improved flexibility (2 GPa in modulus). It was therefore evident that the drawn films of PLLA–PEs triblock copolymers are highly useful as flexible films that can be controlled by the PEs content.

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The A–B–A triblock copolymers consisting of PLLA and polyethers (PE: PEG and PN) were synthesized by the ROP of l-lactide in the presence of telechelic PE as the macroinitiators. The drawn films of these block copolymers were found to compete with the conventional petroleum plastic films and exceed the current biobased and biodegradable polymer films in terms of toughness. Thus, the oriented copolymer films were shown to be highly useful for flexible PLLA-based films.