Advanced Materials Interfaces最新文献

Recent biomedical applications demand piezoelectric polylactide (PLA)-based polymers, possessing biodegradable and biocompatible properties for tissue regeneration, implantable force sensors, and energy harvesting devices. However, piezoelectric poly(L-lactide) (PLLA) possesses weak piezoelectric properties in comparison to non-biodegradable poly(vinylidene fluoride) (PVDF), limiting its application. This contribution presents, for the first time, a nanocomposite strategy to enhance the piezoelectric properties of PLLA, while maintaining cytocompatibility. Biocompatible and piezoelectric barium titanate (BTO) nanoparticles (NPs) are coated by polydopamine (PDA) (cBTO NPs) to improve the quality of the matrix-filler interface and enhanced the force transmission toward the BTO NPs. Electrospun PLLA/cBTO nanocomposite microfiber scaffolds with 5 wt% of PDA-coated BTO NPs (cBTO) exhibited an increase in piezoelectric properties of 120% in comparison to pristine PLLA microfiber scaffolds, implying a voltage output increase from 1.4 ± 0.1 to 3.2 ± 0.2 V. Furthermore, the PDA-coating of BTO (cBTO) NPs itself has an intensifying impact on the piezoelectric properties of PLLA/cBTO nanocomposite compared to non-coated BTO NPs, increasing the voltage output by 41%. This demonstrates the great potential of PDA-coating of piezoelectric NPs to enhance the piezoelectric response of PLLA.

Silicon Carbide

The wide bandgap semiconductor material Silicon Carbide (SiC) is an attractive proposition to replace Silicon for the development of advanced novel power electronic devices, such as superjunction devices. Trench refill epitaxy (TFE) has been developed, where semiconductor processing techniques have been used to create microstructures in SiC and refilled with single crystal SiC to fabricate these exotic superjunction structures. More details can be found in article 2400466 by Vishal Shah and co-workers.

Thermal interface materials (TIMs), which consist of polymers and thermally conductive fillers, are crucial for improving heat dissipation. This study examines the impact of surface functionalization of Si₃N₄ thermal conductive fillers on the performance of TIMs. Si₃N₄ fillers are modified with silane coupling agents of varying alkyl chain lengths, producing fillers with contact angles ranging from 25° to 151.2°, thereby ensuring enhanced interfacial compatibility with various polymers. The modified fillers are incorporated into three common polymers—silica gel (SG), epoxy resin (EP), and polyurethane (PU)—to fabricate TIMs. When the contact angle of Si₃N₄ fillers is 73.3°, they demonstrate excellent interfacial compatibility with EP, leading to a 54.37% increase in thermal conductivity and a 162.75% enhancement in elongation at break for the TIM. At a contact angle of 132.7°, the TIMs prepared with SG exhibit an 86.36% increase in thermal conductivity and a 23.88% increase in elongation at break. Given that the original Si₃N₄ already possesses adequate interfacial compatibility with PU, no further modification is required. These findings offer valuable insights for future research aimed at optimizing Si₃N₄ fillers and TIMs to achieve enhanced thermal and mechanical properties.

Nanomembranes (NMs) made from single-crystalline inorganic semiconductors offer unique properties, such as flexibility, transparency, and tunable bandgaps, making them suitable for complex device integration and next-generation high-power devices. In this study, the fabrication of a high-performing emitter and base (E-B) diode using transferable NMs of n-AlGaAs/p-GaAsP is demonstrated. Using a modified epitaxial lift-off and transfer method, a single-crystalline n-AlGaAs/p-GaAsP fragile NMs transfer onto ultrathin oxide (UO) grown GaN and Si substrates. The crystalline quality of the NMs is characterized by X-ray diffraction and Raman spectroscopy techniques before and after transfer, no noticeable degradation has been found in its crystalline quality. In addition, atomic force microscopy and scanning electron microscopy images confirm the smooth surface and uniformity of the NMs over the whole substrate without any formation of cracks, respectively. Kelvin probe force microscopy demonstrates the formation of a nanoscale contact potential barrier at the interface of the E-B diode. Furthermore, current–voltage (I–V) measurements demonstrate that the performance of the NM-based E-B diode is comparable to that of a rigid diode on the as-grown sample. The findings highlight the potential of the epitaxial lift-off and transfer method for the heterogeneous integration of III–V semiconductor materials to overcome the lattice-mismatch limitations.

Certain metal oxides exhibit unique phases and associated properties that can generally only be accessed via high temperature treatments. However, high temperature processes usually lead to surface reconstruction and pore collapse, which reduces the active surface area. In this study, a novel method for accessing phases is demonstrated at high temperature while maintaining porosity by depositing thin oxide films onto a temperature stable activated carbon template. Subsequent annealing and calcination creates the phase of interest while maintaining the porous structure. Specifically, stoichiometrically limited liquid phase atomic layer deposition is used to deposit 6, 9, 12 and 15 layers of amorphous alumina, which, following high temperature treatment, led to a mixture of α and δ phases with surface areas of 186 and 146 m² g⁻¹ for 6 and 9 layers respectively. Pure α alumina can also be achieved with high surface areas of 76 and 45 m² g⁻¹ for 12 and 15 layers. Importantly, all the samples retained the porosity imparted by the carbon structure, with primarily meso and macro pores. Furthermore, different metal oxides are also deposited onto the activated carbon surface, including ZnO, TiO₂, ZrO₂, and Ga₂O₃ illustrating this templating concept can also be applied to different materials.

Bone tissue engineering seeks to develop treatment approaches for nonhealing and large bone defects. An ideal biodegradable scaffold will induce and support bone formation. The current study examines bone augmentation in critical-sized bone defects, using functionalized scaffolds, with the hypothesized potential to induce skeletal cell differentiation. 3D printed, porous poly(caprolactone) trimethacrylate (PCL-TMA900) scaffolds are applied within a murine femur defect, stabilized by a polyimide intramedullary (IM) pin. The PCL-TMA900 scaffolds are coated with i) elastin-like polypeptide (ELP), ii) poly(ethyl acrylate) (PEA)/fibronectin (FN)/bone morphogenetic protein-2 (PEA/FN/BMP-2), iii) both ELP and PEA/FN/BMP-2, or iv) Laponite nanoclay binding BMP-2. Sequential microcomputed tomography (µCT) and histological analysis are performed. PCL-TMA900 is robust and biocompatible and when coated with the nanoclay material Laponite and BMP-2 induce consistent, significant bone formation compared to the uncoated PCL-TMA900 scaffold. Critically, the BMP-2 is retained, due to the Laponite, producing bone around the scaffold in the desired shape and volume, compared to bone formation observed with the positive control (collagen sponge/BMP-2). The ELP and/or PEA/FN/BMP-2 scaffolds do not demonstrate significant or consistent bone formation. In summary, Laponite/BMP-2 coated PCL-TMA900 scaffolds offer a biodegradable, osteogenic construct for bone augmentation with potential for development into a large scale polymer scaffold for clinical translation.

Since the first report of ferroelectric HfO₂ in 2011, researchers are making rapid progress in the understanding of both material properties and applications. Due to its compatibility with complementary metal oxide semiconductor, high coercivity voltage and the fact that ultrathin films remain ferroelectric, it is developed for applications in non-volatile memories for data storage in different polarization states. As the most representative hafnium-based ferroelectric materials, Hf_0.5Zr_0.5O₂ has received a great deal of attention due to its various of outstanding properties. Magnetron sputtering is a promising method for the preparation of ferroelectric HfO₂ films. This paper reviews recent developments in preparing Hf_0.5Zr_0.5O₂ ferroelectric films and memories. Meanwhile, due to the many advantages of sputtering, such as higher throughputs, low cost and no carbon contamination, this review mainly focused on the preparation of Hf_0.5Zr_0.5O₂ ferroelectric thin films by sputtering and explored its working mechanism and optimization strategy. In addition, the factors affecting the reliability of the memories, the mechanism of action, the solution ideas are introduced. These provide the basis for the design and optimization of Hf_0.5Zr_0.5O₂ ferroelectric films and memories.

In-vitro models are fundamental for studying muscular cell contractility and for wide-screening of therapeutic candidates targeting skeletal muscle diseases, owing to their scalability, reproducibility, and circumvention of ethical concerns. However, in-vitro assays permitting reliable electrical stimulation of cell contractile activity still require technological development. Here, a novel approach to electrically stimulate differentiated muscular cell contractility is reported exploiting the ionic conductivity and mechanical flexibility of 3D nanofibrous scaffolds. The electrospun poly(L-lactide-co-caprolactone) scaffold allowed for C2C12 murine myoblasts horizontal elongation and myotubes formation. Scaffold porosity enables high ionic conductivity and strong electric field generation, orthogonally oriented to the scaffold surface. Electrically induced cell contractility is determined with atomic force microscopy (AFM) enabling real-time monitoring of scaffold vibrations in liquid environment. Differentiated cell actuation is found to be linearly correlated to current amplitude and number of current stimuli. Integrating the 3D nanofibrous scaffolds with real-time AFM monitoring provides highly accurate in-vitro assays for biomedical research. The induction of electric fields orthogonal to the scaffold surface allows for accurately mimicking the excitation-contraction coupling mechanism observed in native skeletal muscle tissue. This work paves the way for the quantitative study of muscular cell dynamic behavior and physiology, further evaluating therapy effectiveness for muscular pathologies.