Macromolecular Materials and Engineering最新文献

Microneedles offer a minimally invasive alternative to hypodermic needles for drug delivery and point-of-care diagnostics. Previous studies on microneedle insertion force often used human skin with constant mechanical properties. However, this study, for the first time, investigates the combined effect of human age (29–68 years) and other variables such as insertion velocity (3 and 4.5 m/s), material (poly(glycolic acid) (PGA), Vectra MT-1300, and Zeonor 1060R) and geometry (cone-shaped and tapered cone-shaped) on insertion force using finite element analysis (FEA). The results show that insertion force increases significantly with age due to higher stratum corneum (SC) stiffness and failure criteria. For example, for a PGA cone-shaped microneedle at 4.5 m/s, the insertion force is 111.56%, 64.09%, 36.46%, and 10.52% higher for individuals aged 68, 53, 41, and 33 years, respectively, compared to 29 years. Microneedle material also significantly affects insertion force, with stiffer materials requiring less force to penetrate the SC. Cone-shaped microneedles exhibit lower insertion forces than tapered cone-shaped designs due to their smaller tip angle. Increasing insertion velocity substantially reduces the insertion force, with higher velocity having a more evident effect than changes in microneedle geometry. Finally, stress distribution within the microneedle and skin deformation are evaluated.

Designing conductive nanocomposites by localizing/trapping a conductive nanofiller at the polymer/polymer interface is quite challenging and considered very dynamic. In this work, the interface developed in poly(ethylene furanoate)/polyethylene (PEF/PE) blends is studied and evaluated for strategic localization of graphene at the interface. The trapping of graphene at the interface was confirmed by extraction of individual components as well as a sharp increase in the electrical conductivity of the PEF/PE/graphene nanocomposites. The sequence of mixing PEF, PE, and graphene showed significant effects on graphene's localization. The inclusion of graphene reduced the characteristic domain size by inducing compatibility in PEF/PE. The PEF/PE interface acts as an energy well that does not allow diffusion of graphene nanosheets into or away from the interface by annealing at high temperatures. Furthermore, adding a compatibilizer affected conductivity negatively, attributed to the altered morphology in blends. The PEF/PE/graphene nanocomposites achieved a low percolation threshold of 0.97 vol%, whereas electrical percolation in PEF/GNP and PE/GNP nanocomposites was observed at 6–7 vol%. A 3D graphene network was confirmed in PEF/PE/GNP nanocomposites via power-law conductivity model. This is the first report on electrically conductive PEF-blends highlighting the potential of interfacially-localized graphene in optimizing the multifunctional properties of bio-based PEF.

The cooperative gelation of sPS with the short PEGDME molecules (molecular weight M_W = 1.5 kg mol⁻¹) from a common THF solution is driven by the gelation tendency of sPS at a temperature around 40°C. The crystalline junctions in the wet gel are fibrillar morphologies, which are typically composed of sPS and PEG molecules, as shown by contrast variation SANS, and consist of sPS, which co-crystallizes in d-form with the solvent molecules, and to a certain extent with PEGDME molecules, as demonstrated by the conformational change of both polymer types from an amorphous to a helical form when the gelation temperature is exceeded, which was observed by in situ FTIR. XRD and SEM on drying gels have shown that the large-scale morphology of dry gels, when the polymer strands collapse and crystalline polymer strands are formed, is determined by the presence and length of the PEGDME molecules. While the sPS dry gel exhibits a more homogeneous distribution of polymer strands and well-defined pores, the polymer strands of the gel with short PEGDME connect at one end to form “tufted” macroassemblies, which, due to the additional co-crystallization of PEGDME with sPS, leads to very large pores and voids.

The demand for corneal tissue replacements increases due to corneal diseases, prompting the exploration of tissue engineering (TE) solutions using biopolymers. Poly (glycerol sebacate) (PGS) is one of the promising biomaterials to be explored in the ocular TE, not only because of its biocompatibility, biodegradability, and elasticity, but also its transparency. However, its low molecular weight and low glass transition temperature (Tg) make PGS scaffold fabrication via electrospinning challenging. Here, we fabricated fibrous membranes by electrospinning of PGS and poly (vinyl alcohol) (PVA) blend and obtained a membrane composed of homogenous fibers with a diameter of 4 µm and a porosity of 28%. In addition, the membrane exhibited a stiffness of 12 MPa and strain of 20%. The permeability of the membrane closely resembled that of the natural cornea with 9.8E-07 cm²/s. Most of the PVA was successfully washed off, resulting in biocompatible scaffold that was able to support the proliferation of human corneal epithelial cells (HCEC) and human corneal endothelial cells (HCEndC) for a week. According to the in vitro biocompatibility assay, HCEC has demonstrated an 88% and HCEndC a 96% viability on electrospun PGS membranes. These results demonstrate the suitability of electrospun PGS membrane for cornea tissue engineering.

Anion exchange membranes (AEMs), which serve as one of the key components in fuel cells, fulfill dual functions: conducting hydroxide ions and blocking the anode and cathode. To balance the relationship between ionic conductivity, mechanical properties, and dimensional stability, quaternized polydopamine (QPDA) nanoparticles were synthesized via a three-step process, including dopamine self-polymerization, grafting with branched polyethylenimine, and quaternization. These QPDA nanoparticles were subsequently used as a novel nanofiller to modify a blend quaternized chitosan (QCS) and polyvinyl alcohol (PVA) polymer, resulting in the QPDA/QCS-PVA composite membranes. The composite samples exhibited improved water uptake, dimensional stability, and ionic conductivity. With the optimal QPDA loading of 6%, the composite membrane achieved a conductivity of 48.4 mS cm⁻¹ at 80°C, which was 2.27 times that of the pure membrane (21.3 mS cm⁻¹). The membranes also demonstrated enhanced mechanical properties and alkaline stability, benefiting from the uniform dispersion of QPDA nanoparticles and chemical cross-linking within the composite system. These QPDA/QCS-PVA composite membranes with an optimal balance between performance and stability can be expected to be novel biomass-based AEMs.

The integration of advanced materials with new fabrication techniques is crucial for advancing bioelectronics. Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is a widely used conductive polymer, but its printability remains challenging due to low viscosity in aqueous solutions. Here, we present 3D freeze-printing to fabricate binder-free, high-conductivity PEDOT:PSS structures. Utilizing a temperature-controlled plate, 3D structures can be formed by direct extrusion printing of dimethyl sulfoxide (DMSO)-doped PEDOT:PSS solutions that are typically unprintable using conventional methods due to spreading and poor shape retention. Freeze-printing at temperatures just below 0 °C increases PEDOT:PSS conductivity by more than 350% compared to room temperature printing. Characterizations using Raman spectroscopy, XRD, and XPS indicate the presence of freezing-induced phase separation and polymer chain alignment, contributing to enhanced conductivity. Critically, our mild fabrication approach enables direct printing onto thermally sensitive materials, such as alginate hydrogels, achieving ∼50% reduction in interfacial impedance at 1 kHz. Unlike other methods requiring multi-day pre- or post-processing under harsh conditions, our approach enables rapid fabrication within a few hours, without the use of harsh chemicals. This work introduces a broadly applicable strategy for patterning conducting polymers with mixed conductivities on soft substrates, suitable for applications in bioelectronics, soft robotics, and wearable sensing devices.

Combining UV radiation with vapor phase polymerization (VPP) enables the fabrication of conducting polymer films with tunable electrical, optical, and electrochemical properties. However, traditional mask-based UV exposure typically requires separation between a photomask and the sample, which limits resolution. This study circumvents this by using a maskless UV exposure system that directly projects high-resolution patterns onto the substrate. Using poly(3,4-ethylenedioxythiophene):toluenesulfonate (PEDOT:Tos) as a model material, the resulting minimum feature sizes are approximately 8 µm—nearly half of what has been achieved using mask-based systems. We find that the obtained resolution is not limited by the optics but is related to material aspects such as molecular diffusion, providing guidelines for further optimizations. Our findings also show that the total delivered dose, rather than exposure time or irradiance, controls the film properties. The resulting PEDOT:Tos patterns exhibit distinct, stable color variations during electrochemical switching, highlighting the potential of maskless UV-VPP for high-resolution electrochromic displays.

Significant advancements in developing high-performance, sustainable tyre tread compounds have been achieved through the strategic integration of modified silica into carbon black (CB)/thermally exfoliated graphite hybrid filler systems. While the benefits of hybrid fillers such as CB, graphite, and silica are recognized, limited understanding of their interaction mechanisms with polymer chains has hindered widespread adoption. This study investigates the mechanical, thermal, and dynamic mechanical properties of an eco-friendly, green tyre tread compound, focusing on both binary (CB/silica) and ternary (CB, exfoliated graphite/modified silica) filler systems. The key aspect of this research is the utilization of modified silica prepared by the latex imprinting technique along with epoxidized natural rubber (ENR) as a compatibilizer to enhance interaction between silica and the NR matrix. The partial replacement of CB with thermally exfoliated graphite and a novel latex-imprinted modified silica with enhanced surface area provides excellent tyre tread properties, such as low rolling resistance, improved wet grip, and reduced heat build-up. The enhanced surface area and porosity of the modified silica, coupled with the hybrid filler system, play a crucial role in reducing hysteresis, resulting in low rolling resistance (0.0376), improved wet grip (0.0796), and very low heat build-up (13°C). This is attributed to the uniform dispersion of modified silica within the polymer matrix, which facilitates improved filler–polymer interactions leading to the development of more sustainable, fuel-efficient tyre tread compounds.

RETRACTION: E. Guler, H. B. Yekeler, B. Uner, M. Dogan, A. Asghar, F. Ikram, Y. Yazir, O. Gunduz, D. M. Kalaskar and M. E. Cam, “In Vitro Neuroprotective Effect Evaluation of Donepezil-Loaded PLGA Nanoparticles-Embedded PVA/PEG Nanofibers on SH-SY5Y Cells and AP-APP Plasmid Related Alzheimer Cell Line Model,” Macromolecular Materials and Engineering 310, no. 3 (2025): 2400160, https://doi.org/10.1002/mame.202400160.

The above article, published online on 24 October 2024 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the journal Editor-in-Chief, David Huesmann; and Wiley-VCH GmbH. The retraction has been agreed upon due to an overlap observed between the image presented in Figure 2a of this article and an image published elsewhere earlier by some of the same authors. Furthermore, inconsistencies in the data presented in Figure 9 were found. The authors could not provide all the raw data required to support the claims of the article. Due to the nature of the concerns and the lack of supporting data, the editors have lost confidence in the results and conclusions of this article. E. Guler, H. B. Yekeler, M. Dogan, A. Asghar, F. Ikram, Y. Yazir, O. Gunduz, D. M. Kalaskar and M. E. Cam agree with the retraction. B Uner did not respond when asked to agree to the final wording of the retraction.

This study explores Poly(lactic-co-glycolic acid) (PLGA)-based scaffolds modified with 10 wt% polycaprolactone (PCL), polylactic acid (PLA), and polyurethane (PU) to enhance their performance. The composite films were characterized by tensile testing, degradability, water absorption, thermal stability, and cell viability. The PLGA/PU group exhibited improved flexibility, while PLGA/PLA showed optimal water absorption (28%) and increased wettability. Contact angle measurements revealed a reduction in hydrophobicity for the PLA (44.4 ± 1 degrees) and PU (43.3 ± 1.6 degrees) groups. Thermal analysis confirmed enhanced thermal resistance for the PLGA/PLA and PLGA/PU composites, making them suitable for applications requiring thermal stability. Additionally, the MTT assay demonstrated over 90% cell viability for the PLGA/PLA group, underscoring its biocompatibility. These findings highlight the potential of PLGA/PLA composites for bone scaffold applications, particularly in additive manufacturing. This study demonstrates that incorporating PLA into PLGA improves key scaffold properties and offers a versatile material for advanced bone tissue engineering.