Macromolecular Research最新文献

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.

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.

Star-shaped poly(l-lactide) (starPLLA) and poly(d-lactide) (starPDLA) were synthesized, and their terminal groups were capped with cinnamate functionalities to obtain cinnamate-terminated star-shaped polylactides (C-starPLLA and C-starPDLA). It was confirmed that both starPLLA and C-starPLLA showed better solubility in various organic solvents than their corresponding linear polylactides. Polymer films of C-starPLLA and its blends with C-starPDLA (C-starPLLA/PDLA) were effectively crosslinked by UV irradiation. The molecular weights of the films were found to become higher when the irradiation was done after annealing the films, suggesting that the increased polymer crystallization by the annealing ought to promote the concentration of the cinnamate functionalities in the amorphous domain, inducing the subsequent terminal photo-crosslinking more efficiently. Furthermore, the aqueous emulsions of C-nPLAs and C-starPLAs were successfully prepared and used for fabrication of their films by emulsion casting. When the resultant polymer films were annealed and UV-irradiated, the film was found to become much harder due to the higher degree of crosslinking. These results supported that the star-shaped structure with photo-crosslinkable terminals should be an effective approach to provide PLAs having improved processability and properties simultaneously.

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Star-shaped poly(L-lactide) (starPLLA) and poly(D-lactide) (starPDLA) were synthesized, and their terminal groups were capped with cinnamate functionalities to obtain cinnamate-terminated star-shaped polylactides (C-starPLLA and C-starPDLA). It was confirmed that both starPLLA and C-starPLLA showed better solubility in various organic solvents than their corresponding linear polylactides. Polymer films of C-starPLLA and its blend with C-starPDLA (C-starPLLA/PDLA) were effectively crosslinked by UV irradiation. These results supported that the star-shaped structure with photo-crosslinkable terminals should be an effective approach to provide PLAs having improved processability and properties simultaneously.

Continual miniaturization and increased power density of microelectronic devices lead to greater heat generation, necessitating the use of thermal interface materials with superior thermal conductivity to ensure device reliability and safety. This study utilizes non-equilibrium molecular dynamics (NEMD) simulations to investigate the enhancement mechanisms of thermodynamic and mechanical properties in hexagonal boron nitride/epoxy resin (h-BN/EP) composites upon the addition of aliphatic (C₅H₁₂O), covalent (silane coupling agent KH560), and non-covalent (dopamine, DA) functional groups. The results indicate that functionalizing h-BN with these groups significantly enhances the thermal conductivity of the epoxy composites, especially when two types of functional groups are used simultaneously. In particular, composites modified with KH560-treated DA exhibited the highest increase in thermal conductivity, achieving 0.761 W·m⁻¹·K⁻¹ with only 10% vol h-BN filler. Additionally, the dual-modified composites also showed a significant improvement in Young's modulus, reaching 7.908 Gpa, an increase of 26.97% over traditional EP. Vibrational density of states (VDOS) analysis confirmed that the aromatic and covalent structures in the functional groups facilitate thermal dissipation. This study offers critical theoretical insights into the improved heat transfer and filler-interface interactions in functionalized h-BN/EP composites, providing a foundation for developing high-performance thermal management materials in advanced electronic systems.

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Comparison of thermal and mechanical properties of epoxy resin composites after functional group modification

How to produce and fabricate polyvinyl alcohol–chitosan (PVA/CS) electrospun nanofibers to investigate the diameter and morphology of the fibers produced by experimental design software was investigated. The effects of voltage (14.32–17.05 kV), feed rate (0.2–2 ml/min), and PVA/CS mixing ratio (50–100 wt%) were studied to obtain optimal electrospinning conditions to achieve the minimum diameter and number of beads. Central Composite Design (CCD) was used to investigate and optimize the processing factors of PVA/CS nanofiber production. The nanofibers were examined using Scanning Electron Microscopy (SEM) and Fourier-Transform Infrared Spectroscopy (FTIR). Nanofibers with diameters ranging from 40 to 250 nm were obtained. The presence of PVA/CS and functional compounds related to both substances in the resulting infrared spectra was confirmed. The results of CCD showed the effect of each variable on the diameter and quality of the fibers and finally suggested the optimal conditions.

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Chemotherapy is the most popular anti-cancer therapy; however, it usually leads to severe side effects to healthy organs because of its high cytotoxicity and poor lesion selectivity. Although various smart carriers have been developed to provide beneficial properties for the local delivery of chemotherapy, it remains challenges in the efficiency and sustained release of drugs. Injectable hydrogels are more advantageous over other drug delivery systems owing to their unique properties, such as non-invasive administration, easy drug loading and locally controlled release at the target sites. Herein, “click” reaction between thiolated hyaluronic (HA–SH) and cyclodextrin–vinyl sulfone (CD–VS) has been used to formulate an injectable hydrogel system for the local delivery of an anticancer drug (Doxorubicin) to cancer cells. This strategy can rapidly induce hydrogelation, while increasing the loading, retention, and sustained release of DOX at the tumor sites through the formation of inclusion complexes between drugs and cyclodextrin. The physico-chemical features of hydrogels, such as gelation time, swelling ratio, porosity, and degradation rate were investigated by varying the concentrations of CD–VS crosslinker. The sustained and pH-sensitive release of DOX from hydrogels were also examined. Finally, the cell viability of the blank hydrogel, free DOX, and DOX-loaded hydrogel was studied by WST-1 and live/dead assay on HELA cells, which exhibited excellent biocompatibility of blank hydrogel and a dose-dependent cytotoxicity of DOX-loaded hydrogels. Therefore, this HA-based hydrogel will be a potential injectable carrier for the targeted and sustained delivery of chemotherapy drugs in cancer treatment.

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