Project description:In the rapidly growing area of high-frequency communications, polyimide films with ultralow dielectric constant and dielectric loss, adequate insulating strength, and recyclability are in high demand. Using a synthesized soluble fluorinated polyimide, a series of recyclable porous dielectric films with varying porosities were fabricated in this study through nonsolvent-induced phase separation. By manipulating the mass ratio of the binary solvent used to dissolve the polyimide, the shape, size, and size distribution of the pores generated throughout the polyimide matrix can be accurately regulated. The porosity and average pore size of the as-prepared porous films were adjustable between 71% and 33% and between 9.31 and 1.00 μm, respectively, which resulted in a variable dielectric constant of 1.51-2.42 (100 kHz) and electrical breakdown strength of 30.3-119.7 kV/mm. The porous sPI film with a porosity rate of 48% displayed a low dielectric constant of 2.48 at 10 GHz. Coupled with their superior thermal stability, mechanical characteristics, and recyclability, these porous polyimide films are highly promising for constructing high-frequency microelectronic devices.
Project description:Ordered mesoporous carbons (OMCs), obtained by nanocasting using ordered mesoporous silicas (OMSs) as hard templates, exhibit unique arrangements of ordered regular nanopore/nanowire mesostructures. Here, we used nanocasting combined with hot-pressing to prepare 10 wt% OMC/OMS/SiO2 ternary composites possessing various carbon mesostructure configurations of different dimensionalities (1D isolated CS41 carbon nanowires, 2D hexagonal CMK-3 carbon, and 3D cubic CMK-1 carbon). The electric/dielectric properties and electromagnetic interference (EMI) shielding efficiency (SE) of the composites were influenced by spatial configurations of carbon networks. The complex permittivity and the EMI SE of the composites in the X-band frequency range decreased for the carbon mesostructures in the following order: CMK-3-filled > CMK-1-filled > CS41-filled. Our study provides technical directions for designing and preparing high-performance EMI shielding materials. Our OMC-based silica composites can be used for EMI shielding, especially in high-temperature or corrosive environments, owing to the high stability of the OMC/OMS fillers and the SiO2 matrix. Related shielding mechanisms are also discussed.
Project description:High dielectric constant polymers have been widely studied and concerned in modern industry, and the induction of polar groups has been confirmed to be effective for high permittivity. However, the way of connection of polar groups with the polymer backbone and the mechanism of their effect on the dielectric properties are unclear and rarely reported. In this study, three polyimides (C0-SPI, C1-SPI, and C2-SPI) with the same rigid backbone and different linking groups to the dipoles were designed and synthesized. With their rigid structure, all of the polyimides show excellent thermal stability. With the increase in the flexibility of linking groups, the dielectric constant of C0-SPI, C1-SPI, and C2-SPI enhanced in turn, showing values of 5.6, 6.0, and 6.5 at 100 Hz, respectively. Further studies have shown that the flexibility of polar groups affected the dipole polarization, which was positively related to the dielectric constant. Based on their high permittivity and high temperature resistance, the polyimides exhibited outstanding energy storage capacity even at 200 °C. This discovery reveals the behavior of the dipoles in polymers, providing an effective strategy for the design of high dielectric constant materials.
Project description:This study addresses the limitations of traditional polyimides (PIs) in high-frequency and high-temperature soft electronic applications, and then introducing trifluoromethylbenzene (TFMB) into the molecular structure and employing various diamines as connecting components to solve the bottleneck. The innovative molecular design enhances thermal, mechanical, and dielectric properties, overcoming challenges in balancing these performances. The optimized fluorinated PI (TPPI50) exhibits exceptional properties, including a glass transition temperature of 402 °C, thermal decomposition temperature of 563 °C, tensile strength of 232.73 MPa, elongation at break of 26.26%, and dielectric constant of 2.312 at 1 MHz with a dielectric loss as low as 0.00676. These improvements are attributed to the unique synergy between TFMB's fluorinated groups, which reduce molecular polarization, and the biphenyl structure, which reinforces chain stability. Compared to conventional PIs, TPPI50 demonstrates superior comprehensive performance, making it highly suitable for soft circuits, high-frequency signal transmission, and advanced applications such as wearable devices and biosensors. This study provides a robust framework for industrial applications, offering a path to next-generation soft electronics with enhanced reliability and performance.
Project description:Ordered mesoporous silica materials gain high interest because of their potential applications in catalysis, selective adsorption, separation, and controlled drug release. Due to their morphological characteristics, mainly the tunable, ordered nanometric pores, they can be utilized as supporting hosts for confined chemical reactions. Applications of these materials, however, are limited by structural design. Here, we present a new approach for the 3D printing of complex geometry silica objects with an ordered mesoporous structure by stereolithography. The process uses photocurable liquid compositions that contain a structure-directing agent, silica precursors, and elastomer-forming monomers that, after printing and calcination, form porous silica monoliths. The objects have extremely high surface area, 1900 m2/g, and very low density and are thermally and chemically stable. This work enables the formation of ordered porous objects having complex geometries that can be utilized in applications in both the industry and academia, overcoming the structural limitations associated with traditional processing methods.
Project description:The vibrational dynamics in the sub-THz range of mesoporous silica nanoparticles (MSNs) having ordered cylindrical mesopores was investigated. MCM-41 and SBA-15 particles were synthesized, and their structure was determined using scanning electron microscopy (SEM), low-angle X-ray diffraction (XRD), N2 physisorption analyses, and Raman scattering. Brillouin scattering measurements are reported and enabled determining the stiffness of the silica walls (speed of sound) using finite element calculations for the ordered mesoporous structure. The relevance of this approach is discussed based on the comparison between the numerical and experimental results and previous works reported in the literature.
Project description:Proteins are great therapeutic candidates as endogenous biomolecules providing a wide range of applications. However, their delivery suffers from some limitations and specifically designed delivery systems having an efficient protein anchoring and delivery strategy are still needed. In this work, we propose to combine large pore stellate mesoporous silica (STMS) with isobutyramide (IBAM), as a "glue" molecule which has been shown promising for immobilization of various biomacromolecules at silica surface. We address here for the first time the ability of such IBAM-modified NPs to sustainably deliver proteins over a prolonged time. In this work, a quantitative loading study of proteins (serum albumin (HSA), peroxidase (HRP), immunoglobulin (IgG) and polylysine (PLL)) on STMS@IBAM is first presented using three complementary detection techniques to ensure precision and avoid protein quantification issues. The results demonstrated a high loading capacity for HSA and HRP (≥ ca. 350 μg.mg-1) but a moderate one for IgG and PLL. After evaluating the physicochemical properties of the loaded particles and their stability over scaling-up and washings, the ability of STMS@IBAM to release proteins over prolonged time was evaluated in equilibrium (static) and flow mimicking (dynamic) conditions and at different temperatures (25, 37, 45 °C). Results show not only the potential of such "glue" functionalized STMS to release proteins in a sustained way, but also the retention of the biological activity of immobilized and released HRP, used as an enzyme model. Finally, an AFM-force spectroscopy study was conducted to decipher the interactions between IBAM and proteins, showing the involvement of different interactions in the adsorption and release processes.
Project description:In this study, we developed an approach using Zirconium (IV)-grafted mesoporous beads to enrich phosphopeptides followed by analysis with a high resolution nanoRPLC-MS/MS system. The new method was first tested with tryptic digests of standard phosphoproteins and HeLa cell lysates, with excellent enrichment performance achieved. The method was further used for endogenous phosphopeptidomic analysis of serum samples from pancreatic ductal adenocarcinoma (PDAC) patients and controls. In total, 329 endogenous phosphopeptides (containing 113 high confidence sites) were identified across samples, by far the largest endogenous phosphorylation dataset catalogued to date. In addition, the method was readily applied for phosphoproteomics of the same set of samples, with 172 phosphopeptides identified and significant changes in dozens of phosphopeptides observed. Taken together, this method serves as a benchmark for analyzing serum phosphorylation events. Given the simplicity and robustness of the proposed method, we envision that it can be readily used for comprehensive phosphorylation studies (i.e., simultaneous endogenous phosphopeptidomics and phosphoproteomics) of serum and other biofluid samples.
Project description:Dielectric permittivity, a measure of polarisability, is a fundamental parameter that dominates various physical phenomena and properties of materials. However, it remains a challenge to control the dielectric permittivity of materials reversibly over a large range. Herein, we report an anisotropic fluid with photoresponsive dielectric permittivity (200 < ε < 18,000) consisting of a fluorinated liquid-crystalline molecule (96 wt%) and an azobenzene-tethered phototrigger (4 wt%). The reversible trans-cis isomerisation of the phototrigger under blue and green light irradiation causes a switch between two liquid-crystalline phases that exhibit different dielectric permittivities, with a rapid response time (<30 s) and excellent reversibility (~100 cycles). This anisotropic fluid can be used as a flexible photovariable capacitor that, for example, allows the reversible modulation of the sound frequency over a wide range (100 < f < 8500 Hz) in a remote manner using blue and green wavelengths.
Project description:Quantum computing and quantum information processing (QC/QIP) crucially depend on the availability of suitable quantum bits (qubits) and methods of their manipulation. Most qubit candidates known to date are not applicable at ambient conditions. Herein, we propose radical-grafted mesoporous silica as a versatile and prospective nanoplatform for spin-based QC/QIP. Extremely stable Blatter-type organic radicals are used, whose electron spin decoherence time is profoundly long even at room temperature (up to Tm ≈2.3 μs), thus allowing efficient spin manipulation by microwave pulses. The mesoporous structure of such composites is nuclear-spin free and provides additional opportunities of embedding guest molecules into the channels. Robustness and tunability of these materials promotes them as highly promising nanoplatforms for future QC/QIP developments.