查找使用阿拉丁产品的科研文献

Double layer lift-off nanofabrication controlled gaps of nanoelectrodes with sub-100 nm by nanoimprint lithography

Shujie Wang,Qing Shi,Jing Chai,Ke Cheng,Zuliang Du

Basic research on nanoelectronics is often limited by the high cost and large-scale methods to fabricate electrodes with controlled gap size in nanometer scales. Here nanoelectrodes with a controlled gap size of sub-100 nm were fabricated by modified nanoimprint lithography (NIL) via a double-layer lift-off process utilizing polymethylmethacrylate (PMMA) and polydimethylglutarimide (PMGI) as the lift-off resist. Firstly the patterns of the electrode mold were transferred onto the upper PMMA layer by NIL techniques and then through controlling the developing time and concentration of developer of the PMGI under layer, regulating the exact gap size of the transferred metal nanoelectrode. The result indicated that the 'undercut' phenomenon was observed of the PMGI transfer layer during the developing process; through controlling the feature size of the undercut length, the gap size of the transferred metal nanoelectrode was precisely controlled, which showed shrinkage behavior. The nanoelectrodes with gap sizes of 800, 400, 200, and 100 nm can be reduced to about 440, 120, 80, and 70 nm. Our result provides a low-cost and large-scale route to prepare nanoelectrodes with controlled gap size, which can be valuable for current efforts in nanoelectronics.

Polymeric Foams with Nanoscopic Cellular Structures Facilitated by UiO-66-X as High-Efficiency Nucleators

Shanqiu Liu,Enze Yu,Wei Cui,Taotao Ge,Qing Liu,Yu Zhong,Ping Li,Jie Yu,Jingguo Li

Nanocellular polymer foams are highly valued for their light weight, high strength, and unique nanostructures, offering significant potential for diverse applications. However, their fabrication and practical use are constrained by the low cell nucleation efficiency and the necessity for extremely high-pressure foaming processes. In this work, we successfully fabricated polymethyl methacrylate (PMMA) nanocellular foam featuring a cell density on the order of 1013 cells cm–3 at a relatively low foaming pressure of 6.0 MPa. This accomplishment was achieved through the use of UiO-66-X nanoparticles as nucleation facilitators, which exhibited a high nucleation efficiency of 1.94. Four distinct UiO-66-X nanoparticles, each adorned with different functional groups, were synthesized and proven to act as efficacious nucleators for PMMA nanofoams. The successful synthesis of UiO-66-X nanoparticles and the integration of functional groups were corroborated through Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The cell dimensions and density of the PMMA nanocellual foam were characterized via SEM analyses. Our findings revealed that the incorporation of UiO-66-X nanoparticles dramatically minimized the cell size of the PMMA foam, thereby attaining an elevated cell density. This enhancement is attributed to a reduction in the free energy for cell nucleation within nanocavities situated at the matrix–nucleator interface. Consequently, the meticulous design of high-performance nucleating particles and the judicious selection of foam matrix constituents emerge as pivotal strategies in the quest for polymer cellular materials exhibiting nanoscale cell dimensions. These insights significantly advance the fabrication of polymer foams with enhanced thermal insulation properties and have broad implications for the realm of honeycomb materials science. By optimizing nucleation mechanisms and material combinations, this work paves the way for the development of advanced cellular polymers tailored for applications where superior insulation or light weight yet robust structures are paramount.

Preparation and characterization of temperature-induced ultrasensitive SERS large-scale vertical Au nanosphere dimers

Jianxia Qi,Yuchong Ren,Kangzhe Zhao,Xinyue Li,Wanxuan Chang,Chengyun Zhang,Qingyan Han,Wei Gao,Yongkai Wang,Jun Dong

Plasmonic dimers have a very wide range of applications as a unique platform for studying the fundamental effects of plasmonics. Most dimer structures are prepared by chemical methods and direct-writing methods, such as coupling agents and lithography. These methods are often complex and expensive. Here, we prepared Au nanospheres (AuNSs) by layer-by-layer (LBL) deposition, used polymethyl methacrylate (PMMA) as a spacer layer, and then annealed the deposited AuNSs to orient the assembly and integrate them together. In this paper, suitable PMMA spin coating conditions and optimal annealing temperatures were explored, and large-scale AuNSs-PMMA-AuNSs(NSs-P-NSs) composed of vertical Au nanosphere dimers were prepared successfully. The detection limits of this substrate can reach 4 × 10−12 M/L and 4 × 10−10 M/L for Rhodamine 6 G (R6G) and Crystal Violet (CV), respectively, demonstrating excellent Raman activity. In addition, the sensitivity of detecting aspartame (APM) is 0.015625 g/L. This method is not only simple to operate but also allows the preparation of a large-scale uniform substrate with excellent detection capabilities.

Preparation and characterization of Co(II) ion-imprinted composite membrane based on a novel functional monomer

Li Zhao,Deqiong Hu,Huiling Cheng

In this paper, a novel functional monomer, N-(pyrrolidin-2-ylmethyl) methacrylamide (PMMA), was synthesized. Using Co(II) ions as the template, 2,2-azoisobutyronitrile (AIBN) as the initiator, ethylene glycol dimethacrylate (EDGMA) as the crosslinking agent, twenty-seven Co(II) ion-imprinted composite membranes (Co(II)-PMMA-IICM 1∼27 ) and their corresponding non-imprinted composite membranes (PMMA-NICM 1∼27 ) were prepared. Additionally, the related parameters of the imprinting system were systematically optimized. Co(II) ion-imprinted composite membranes (Co(II)-PMMA-IICM 16 ) were prepared using Nylon-6 as the supporting membrane, which was soaked in a pre-polymerized solution of N,N-dimethylformamide and water (DMF: H 2 O ( v/v ) = 1: 1) for 180 s, using a molar ratio of template, monomer, and crosslinker of 1: 4: 50. The obtained material had a higher adsorption capacity ( Q e  = 428.24 mg g −1 ) and imprinting factor ( IF  = 2.36). The surface and internal porosity of Co(II)-PMMA-IICM 16 were characterized by scanning electron microscopy and a nitrogen adsorption apparatus. In addition, it was found that the adsorption process of Co(II)-PMMA-IICM 16 prepared under optimal conditions was better described by a Langmuir isotherm adsorption model, which verified that the adsorption involved monolayer adsorption. The kinetics data was more closely fit by a pseudo-second-order kinetics model, indicating that this adsorption process proceeded via chemisorption. The permeation experiments indicated that a “delayed” permeation mass transfer mechanism also occurred ( β (Co(II)/Cd(II))  = 2.11 and β (Co(II)/Cu(II))  = 1.55). The Co(II) ion-imprinted composite membrane prepared in this paper demonstrated a relatively better imprinting effect, a specific recognition ability for template ions, and good selective permeability. These results validated that the design of this novel functional monomer was reasonable, and that it has potential applications in various fields where adsorption is necessary.

An organic microlaser based on an aggregation-induced emission fluorophore for tensile strain sensing

Xiaoping Guo,Shijie Zhen,Tianchang Ouyang,Shangxiong Zhou,Qiwen Pan,Dandan Yang,Jianhao Chen,Guoping Dong,Zujin Zhao,Jianrong Qiu,Ben Zhong Tang

With the wide use of micro–nano photonic devices in on-chip optical communication, physical and chemical sensing, organic microlasers have gained increasing attention owing to their special advantages including high integration, easy preparation and excellent optical properties. However, traditional microlasers suffer from the “aggregation-caused quenching” (ACQ) effect of gain molecules and high lasing thresholds. In this contribution, we meticulously designed organic microlaser assemblies based on an “aggregation-induced emission” (AIE) fluorophore for its unique characteristics. An innovative AIE fluorophore, namely triphenylamine-benzo[1,2-b:4,5-b′]-dithiophene 1,1,5,5-tetraoxide (TPA-BDTO), with highly efficient emission at the aggregated state is employed to hybridize with the PMMA matrix, obtaining microbottles with an ultra-smooth surface via the self-assembled strategy. Benefiting from the spatially well-separated intensity based on the prolate shape of the TPA-BDTO–PMMA microbottle, we realize a single-mode microlaser in a microbottle with an appropriate pump power via precise manipulation. Moreover, the TPA-BDTO–PMMA microlaser is demonstrated as an axial tensile strain sensor with high sensitivity (0.34 pm με−1), high resolution, real-time response and simple structure, which create new opportunities for organic microlasers and even lay a foundation for the research of lab-on-chips.

Improving Perovskite Green Quantum Dot Light-Emitting Diode Performance by Hole Interface Buffer Layers

Qiangqiang Wang,Xuanyu Zhang,Lei Qian,Chaoyu Xiang

Perovskite quantum dot light-emitting diodes (QLEDs) are potential candidates for next-generation displays due to their high color purity and wide color gamut. Due to the strong electron-accepting ability of poly[bis(4-phenyl) (2,4,6-trimethylphenyl) amine] (PTAA), quantum dot (QD) films are prone to be charged, which leads to the imbalance of charge injection and the increase of nonradiative recombination, ultimately affecting the performance of the QLEDs. Here, we compared and studied two polymers, poly(methyl methacrylate) (PMMA) and poly(vinyl pyrrolidone) (PVP), as the hole interface buffer layers of QD films, which effectively reduced the defect density, suppressed nonradiative recombination, and greatly improved the efficiency and stability of QLEDs. The devices with PMMA achieved a maximum external quantum efficiency of 20.71%.

Engineering Defective UiO-66 Metal–Organic Frameworks as Efficient Polymer Foam Cell Nucleating Agents

Shanqiu Liu,Enze Yu,Taotao Ge,Qing Liu,Yu Zhong,Wei Cui,Jie Yu,Jingguo Li

Nanocellular polymer foams are highly valuble for their lightweight nature, high strength, and unique nanostructures, which offer significant potential across a variety of applications. However, their production and practical use are limited by low cell nucleation efficiency and the requirement for extremely high-pressure foaming processes. In this study, we successfully fabricated poly(methyl methacrylate) (PMMA) nanocellular foams with a cell density on the order of 1012 cells cm–3 at a relatively low foaming pressure of 6.0 MPa. This achievement was made possible through the use of defective UiO-66 nanoparticles as nucleation enhancers, which demonstrated a high nucleation efficiency of 1.11. We synthesized four types of defective UiO-66 nanoparticles, each with varying levels of defects, and confirmed their efficacy as nucleators for PMMA nanofoams. The successful synthesis of these defective UiO-66 nanoparticles was verified using Fourier Transform Infrared Spectroscopy, X-ray Diffraction, Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Spectroscopy. The cell size and density of the PMMA nanocellular foams were characterized via SEM analysis. Our findings showed that the incorporation of defective UiO-66 nanoparticles markedly reduced the cell size of the PMMA foam, achieving a higher cell density. This improvement is attributed to a decrease in the free energy required for cell nucleation within nanocavities located at the matrix–nucleator interface. Consequently, the careful design of high-performance nucleating particles and the judicious choice of foam matrix components emerge as critical strategies in developing polymer cellular materials with nanoscale cell dimensions. These insights significantly advance the fabrication of polymer foams with enhanced thermal insulation properties and have broad implications for the field of cellular materials science. By optimizing nucleation mechanisms and material combinations, this work opens new avenues for the development of advanced cellular polymers tailored for applications requiring superior insulation or lightweight yet robust structures.

Low-voltage organic field-effect transistors by using solution-processable high-κ inorganic-polymer hybrid dielectrics

Bin Rong,Wei Zhao,Yi Liao,Yixiao Zhang,Yangyang Zhu,Wei Shi,Bin Wei

Organic field-effect transistors (OFETs) incorporating hybrid high-κ inorganic Al2O3 and polymer dielectrics, including polyvinyl alcohol (PVA), polystyrene (PS), or polymethyl methacrylate (PMMA), through solution-processing techniques were fabricated. The analyses revealed that the high surface energy and hydrophilicity property of Al2O3 and PVA, and the relatively hydrophobic property of PS surface, hindered the performance of corresponding OFETs. The Al2O3/PMMA-based OFET achieved the optimized performance, with a threshold voltage of −2.7 V, a hole carrier mobility of 0.056 cm2/Vs, and a current on/off ratio of 1.0 × 104 at a low operating voltage of −5 V. Through analyzing the characteristics of leakage current, capacitance, contact resistance, and trap density of OFETs, we found that the PMMA-engaged films possessed the optimized electrical properties. The introduction of PMMA eliminated the interfacial trapping, thereby lowering the threshold voltage and enhancing the performance of the device. The COMSOL Multiphysics simulation was conducted to confirm the physical mechanism. The strategy of utilizing Al2O3/PMMA hybrid dielectric could simultaneously ensure the low operating voltage and good performance of OFET, while guaranteeing the low leakage current by the thick PMMA.

Highly luminescent up/down conversion thin films prepared by a room temperature process

Hanyu Yao,Honglie Shen,Quntao Tang

Efficient up/down conversion (UC/DC) thin films with high transmittance were prepared by an anisole dissolved polymethyl methacrylate (PMMA) solution mixed with β-NaYF 4 : 5% Er, 10% Yb (UCNPs) and β-NaYF 4 : 10% Tb, 1% Yb (DCNPs) nanocrystals , which required no postdeposition heat treatment. The full embedment of nanoparticles in the PMMA matrix was confirmed by atomic force microscopy , and the films were dense and uniform with high transmittance. Both UCNPs and as-prepared films exhibited strong UC emission bands in the green and red region. The relative intensities of green to red emissions in the films were enhanced compared with UCNPs because of the surface passivation by PMMA. Under excitation of 355 nm laser, both DCNPs and as-prepared films exhibited down conversion luminescence and no obvious intensity difference was observed between nanoparticles and the films. By tape test, the conversion films were proved with a strong adhesion due to the protection of PMMA. The results suggested that PMMA is a good matrix for fabrication of efficient UC/DC films with high transmittance and good adhesion.

Synthesis of Highly Monodisperse Surface-Functional Microspheres by Photoinitiated RAFT Dispersion Polymerization Using Macro-RAFT Agents

Jianbo Tan,Xin Rao,Jianwen Yang,Zhaohua Zeng

Highly monodisperse PMMA microspheres have been synthesized by photoinitiated RAFT dispersion polymerization in the presence of a Macro-RAFT agent and a small molecular RAFT agent. A particle yield of over 90% was achieved within 3 h under UV irradiation at room temperature. The Macro-RAFT agent acts as a stabilizer and stabilizes the particles via formation of block copolymers in situ, and XPS analysis shows that about 29.9% of the particle surface was covered by the stabilizer. Various surface functional microspheres were prepared by using four kinds of Macro-RAFT agents, including poly(methoxy poly(ethylene glycol) acrylate)-based trithiocarbonate (P(mPEGA)-TTC), poly(methoxy poly(ethylene glycol) acrylate-co-acrylic acid)-based trithiocarbonate (P(mPEGA-co-AA)-TTC), poly(acrylic acid)-based trithiocarbonate (PAA-TTC), and poly(methoxy poly(ethylene glycol) acrylate-co-4-vinylpyridine)-based trithiocarbonate (P(mPEGA-co-4VP)-TTC). Ag/PMMA nanocomposite spheres were prepared using the P(mPEGA-co-AA)-TTC stabilized microspheres. The PAA-TTC stabilized microspheres showed pH sensitivity. The colloidal stability of the particles prepared by this photoinitiated RAFT dispersion polymerization was also investigated.

Neodymium Modified Chitosan/PMMA Integrated Thin-Core Fiber for Trace Fluoride Ion Detection

Yi Jiang,Hongliang Chen,Xiaozhan Yang,Wenlin Feng

Optical and Electrical Characterization of Pure PMMA for Terahertz Wide-band Metamaterial Absorbers

Shi Zaiying,Song Lixin,Zhang Tao

The characteristics of relative permittivity and reflectance for poly (methyl methacrylate) (PMMA) films prepared by spin-coating were investigated and an excellent wideband terahertz (THz) metamaterial absorber (MA) had been fabricated by employing PMMA film as the dielectric layer. XRD and AFM indicated that all the PMMA films with thicknesses from 11 to 17 μm were amorphous and extremely smooth with roughness about 0.203 nm. Raman results demonstrated that vibration strength of the same covalent bonds tends to be consistent with an increase in film thickness. The dual beam laser interferometer (DBLI) was employed to study the influence of applied frequency and thickness on the relative permittivity, and the results exhibited dielectric constants increased from 2.88 to 4.04 with the thickness increasing from 9 to 14 μm. And the dielectric constants for PMMA films with a certain thickness (8 μm) gradually declined when the applied frequency increased from 100 to 10 5  Hz; besides, the dielectric constant in THz band was forecasted approximately 2.5. The terahertz time domain spectrometer (THz-TDS) results revealed that the THz reflectance was of gradual degradation from 80 to 58% at 3.2 THz, as the thickness increased from 11 to 17 μm. In addition, the UV-VIS spectrum showed that thickness had little effect on reflectance and transmittance in visible region, leading to the almost same E g (energy gap) about 3.7 eV. At last, by employing PMMA film as the dielectric layer, a highly wideband metamaterial absorber with absorption > 80% from 4.1 to 7.4 THz was fabricated.