Poly Methyl Methacrylate Layer Research Articles

Enhancement of Dielectric Breakdown Strength and Its Possible Mechanism in Triple-Layered Films Formed by Stacking Resin Layers with Different Relative Dielectric Constants

Abstract Dielectric properties of co-extruded triple-layered films consisting of polymethyl methacrylate (PMMA) sandwiched between polyvinylidene fluoride (PVDF) layers were evaluated. The triple-layered films showed a higher dielectric breakdown strength and a higher energy density than each single-layer film, and the enhancement depended on the volume ratio of the PMMA layer, which has a lower relative dielectric constant than PVDF. The simulation of dielectric breakdown paths using the phase-field model revealed that the middle layer with a lower dielectric constant shares a higher voltage until its dielectric breakdown, resulting in an enhancement of the dielectric breakdown strength in the triple-layered film. The simulation results well matched the experimental data, indicating that controlling the volume ratio and relative dielectric constant of each layer in the triple-layered film is an effective approach to enhancing dielectric breakdown strength. This concept is considered promising for developing dielectric materials that enable a size reduction of film capacitors.

Thermally Isolated Ruthenium Nanobolometer for Room-Temperature Operation

We propose a bolometer intended for room-temperature operation and based on a 100-nm-wide ruthenium (Ru) strip fabricated on a thin layer of cross-linked polymethyl methacrylate (XPMMA). This layer provides thermal isolation between the silicon substrate and the Ru nanostrip for increasing the nonlinearity of the bolometer <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}-{V}$ </tex-math></inline-formula> curve due to more intensive self-heating by the biasing and an ac current. A number of bolometers with Ru strips of different dimensions and different thicknesses of XPMMA layer were fabricated and tested at dc. An estimate based on the dc tests gives the electrical voltage responsivity to radio frequency (RF) signal as much as 250 V/W, which makes the proposed bolometer attractive as a sensing element for a simple and low-cost microwave and terahertz detector. Numerical simulations of temperature distribution along the Ru strip and analysis of the bolometer noise performance are also presented.

Ag NPs/PMMA nanocomposite as an efficient platform for fluorescence regulation of riboflavin.

The fluorescence detection platform has broad application in many fields. In this paper, we report a simple and efficient fluorescence detection platform based on the synergistic effects of Ag nanoparticles (Ag NPs) and polymethylmethacrylate (PMMA). Ag NPs were introduced to realize the plasmon enhancement fluorescence and a thin PMMA layer was used to adjust the distance between Ag NPs and riboflavin. The thin PMMA layer not only enhances the fluorescence by enhancing adhesion of substrate, but also optimizes the plasmon enhancement fluorescence effect by serving as the spacer. The fluorescence enhancement factor based on this platform shows a trend of increasing with the decrease of the concentration of riboflavin, and the detection of riboflavin is realized based on this feature, the lowest detectable concentration is as low as 0.27 µM. In addition to the detection based on plasmon enhancement fluorescence, the detection of riboflavin at low concentrations can also be realized by the shift and broadening of the fluorescence peak due to the Ag NPs. The combination of the two ways of plasmon enhancement fluorescence and shift of the fluorescence spectra is used for the detection of riboflavin. These results show that the platform has great potential applications in the field of detection and sensing.

Epsilon-near-zero substrate-enabled strong coupling between molecular vibrations and mid-infrared plasmons.

As the strong light-matter interaction between molecular vibrations and mid-infrared optical resonant modes, vibrational strong coupling (VSC) has the potential to modify the intrinsic chemistry of molecules, leading to the control of ground-state chemical reactions. Here, by using quartz as an epsilon-near-zero (ENZ) substrate, we have realized VSC between organic molecular vibrations and mid-infrared plasmons on metallic antennas. The ENZ substrate enables sharp mid-infrared plasmonic resonances (Q factor ∼50) which efficiently couple to the molecular vibrations of polymethyl methacrylate (PMMA) molecules with prominent mode splitting. The coupling strength is proportional to the square root of the thickness of the PMMA layer and reaches the VSC regime with a thickness of ∼300 nm. The coupling strength also depends on the polarization of the incident light, illustrating an additional way to control the molecule-plasmon coupling. Our findings provide a new, to the best of our knowledge, possibility to realize VSC with metallic antennas and pave the way to increase the sensitivity of molecular vibrational spectroscopy.

Strong coupling between quasi-bound states in the continuum and molecular vibrations in the mid-infrared

Abstract Strong light–matter coupling is of much interest for both fundamental research and technological applications. The recently studied bound state in the continuum (BIC) phenomenon in photonics with controlled radiation loss rate significantly facilitates the realization of the strong coupling effect. In this work, we report the experimental observation of room temperature strong coupling between quasi-BIC resonances supported by a zigzag metasurface array of germanium elliptical disks and the vibrational resonance of polymethyl methacrylate (PMMA) molecules in the mid-infrared. Based on the approach of tuning the quasi-BIC resonance by changing the thickness of the coated PMMA layer, we can easily observe the strong coupling phenomenon, manifested by significant spectral splitting and typical anti-crossing behaviors in the transmission spectrum, with the spectral distance between the two hybrid photon-vibration resonances significantly larger than the bandwidth of both the quasi-BIC resonance and the PMMA absorption line. Our results demonstrate that the use of quasi-BIC resonance in all-dielectric nanostructures provides an effective and convenient approach for the realization of strong coupling effect.

Development and Characterization of Passivation Methods for Microneedle-based Biosensors.

Microneedles (MN) are short, sharp structures that have the ability to painlessly pierce the stratum corneum, the outermost layer of the skin, and interface with the dermal interstitial fluid that lies beneath. Because the interstitial fluid is rich in biomarkers, microneedle-based biosensors have the potential to be used in a wide range of diagnostic applications. To act as an electrochemical sensor, the tip or the body of the MN must be functionalized, while the substrate areas are generally passivated to block any unwanted background interference that may occur outside of the skin. This work presents four different passivation techniques, based on the application of SiO2, polymethyl methacrylate (PMMA), an adhesive film, and varnish to the substrate areas. Optical, SEM and electrochemical measurements were performed to quantitatively assess the performance of each film. The data shows that whilst manual application of varnish provided the highest level of electrical isolation, the spin-coating of a 5 μm thick layer of PMMA is likely to provide the best combination of performance and manufacturability. Clinical Relevance- Substrate passivation techniques will improve the performance of microneedle-based non-invasive continuous monitoring systems.

Spin-casting of Micron-Scale Thick PMMA Films with Embedded Au Nanoparticles Formed by Laser Ablation in Liquid

Background: A Facile, scalable approach to fabrication of organic thin films with an embedded layer of nanoparticles in the ambient environment. The approach is based on step-bystep spin-coating of polymethylmethacrylate (PMMA) films and a nanoparticle layer. Objective: The goal of the present work is to fabricate a sandwich structure of the PMMA films for the top and bottom layers of a sandwich structure as well as a middle layer of nanoparticles formed in solution by the Laser Ablation in Liquid (LAL) method. Methods: First, a PMMA thin film was fabricated by spin-casting of PMMA solution in ethylacetate. Secondly, a solution of Au nanoparticles synthesized by laser ablation in ethanol was spin-cast on a prefabricated PMMA film. The distribution of Au nanoparticles and the morphology of the resulting film were analyzed using scanning electron microscopy (SEM), optical microscopy, and atomic microscopy (AFM). Finally, another PMMA layer was spin-cast on the nanoparticle-decorated film. Results: A hybrid organic film with the embedded layer of nanoparticles was fabricated using the spin-casting method for top and bottom layers as well as for the middle layer of Au nanoparticles fabricated by laser ablation in ethanol by a pulsed UV laser. Statistical and fractal analysis shows uniform distribution of nanoparticles on length scale above ten microns. Conclusion: Spin-cast-based layer-by-layer approach to fabrication of sandwich structures of organic films with embedded nanoparticlesis a facile and scalable method for hybrid organic - nanoparticle films. This approach can be extended for the fabrication of multi-layered hybrid structures.

Smart Error Sum Based on Hybrid Two-Trace Two-Dimensional (2T2D) Correlation Analysis.

Based on hybrid 2D correlation analysis, we recently derived and introduced a "smart error sum," a sophisticated loss function that can be used for solving nonlinear inverse problems like the determination of optical constants and oscillator parameters from a series of optical spectra in the infrared spectral region. The advantage of the smart error sum compared to the conventional sum of squared errors lies in its ability to marginalize multiplicative systematic errors such as, for example, reflectance values above unity in transflection spectra. This is enabled by a transformation, which allows fits to not exclusively focus on forcing fit spectra to agree with experimental spectra at every wavenumber point by all means, but also to take correlations such as spectral similarities and their changes with certain perturbations into account. In this work, we extend our approach to accommodate the treatment of individual spectra, instead of only series, based on hybrid two-trace two-dimensional (2T2D) correlation analysis. We evaluate and prove the value of our approach by individually analyzing experimental transflection spectra of polymethyl methacrylate (PMMA) layers on gold substrates. The comparison of the results with those obtained by the original smart error sum based on the whole set of spectra as well as those resulting from conventional fitting of series and individual spectra (using the conventional sum of squared errors) confirms the validity and soundness of the 2T2D smart error sum.

Influence of Polymer Interfacial Protective Layer Thickness on the Stability of Lithium‐Metal Batteries

AbstractProtective layers formed of polymers with conjugated structures have been demonstrated to improve the cycling stability of lithium (Li)‐metal batteries by reducing Li dendrite growth. However, the influence of important film parameters, such as thickness and ionic conductivity, remains largely unexplored. The present work addresses this issue by investigating the influence of film thickness for electrochemically active polymethyl methacrylate (PMMA) protective layers on the growth of Li dendrites and the long‐term cycling stability of Li‐metal batteries. The results demonstrate that the cycling stability of cells employing PMMA/Cu electrodes attains a maximum value at an optimal polymer film thickness of 93 nm. The results of detailed analysis indicate that the optimal PMMA layer thickness improves the cycling stability of Li‐metal batteries by eliminating the uneven electric fields on the surface of the Cu electrode leading to Li dendrite growth, and by reducing the interfacial impedance due to the formation of intramolecular cyclopentanedione during the discharge/charge cycling. Accordingly, the results provide effective guidance in the future design of polymer protective layers by demonstrating that film thickness is a key factor influencing the cycling stability of Li‐metal batteries.

Influence of spin casting solvent on the self‐assembly of silicon‐containing block copolymer thin films via high temperature thermal treatment

AbstractThe present paper focuses on the influence of different solvents (toluene, mesitylene, acetone, tetrahydrofuran, propylene glycol monomethyl ether acetate (PGMEA) and ethyl acetate) on the self‐assembly behaviour of cylinder‐forming polystyrene‐block‐poly(dimethylsiloxane‐random‐vinylmethylsiloxane) diblock copolymer films deposited on thin brush layers of polystyrene (PS) or polymethylmethacrylate (PMMA) polymers grafted to a silicon substrate. The morphology and the key metrics for all samples were determined from the analysis of the SEM images and their evolution was investigated, as a function of the annealing time at 310 °C, for each solvent and for both PS and PMMA brushes. In general, shorter correlation lengths ξ are observed on PS brushes than on PMMA brushes. In addition, SEM data analysis reveals that tetrahydrofuran, PGMEA and ethyl acetate solvents promote a morphological change from fingerprint‐like parallel cylinders to a hexagonally packed dot pattern for annealing time tA &gt; 30 s. Finally, the line edge roughness and linewidth roughness values are weakly dependent on both the casting solvent and the nature of the grafted brush. The reported data reveal that the choice of the polymer brush nature and of the solvent employed during the spin coating of the diblock copolymer film could substantially affect the self‐assembly process and requires accurate optimization due to their subtle interplay. © 2021 Society of Industrial Chemistry.

Термодеструкция полиметилметакрилата и его композита с фуллереном C-=SUB=-60-=/SUB=- после ультрафиолетового облучения

The analysis of the ultraviolet induced transformation of the thermal decomposition spectra of the monomer of the submicrometer layers of polymethylmethacrylate and its composite with fullerene C60 for different fullerene concentrations and irradiation doses has been carried out. Formation of the new decomposition stages in the spectra has been interpreted by the binding between C60 and side ester groups of polymethylmethacrylate.

Thermal decomposition of polymethylmethacrylate and its composite with fullerene C-=SUB=-60-=/SUB=- after ultraviolet irradiation

The analysis of the ultraviolet induced transformation of the thermal decomposition spectra of the monomer of the submicrometer layers of polymethylmethacrylate and its composite with fullerene C60 for different fullerene concentrations and irradiation doses has been carried out. Formation of the new decomposition stages in the spectra has been interpreted by the binding between C60 and side ester groups of polymethylmethacrylate. Keywords: polymethylmethacrylate, fullerene, ultraviolet irradiation, thermal decomposition, mass-spectrometry.

PMMA direct exfoliation for rapid and organic free transfer of centimeter-scale CVD graphene

Despite the various techniques developed for the transfer of large area graphene grown by chemical vapor deposition (CVD), the conventional polymethylmethacrylate (PMMA) transferring technique has been widely applied in laboratories due to its convenience and economical cost. However, the complete removal of PMMA on graphene surface has become a troublesome, and the PMMA residue could degrade the properties of graphene significantly. We report here a facile water assisted technique to directly peel off the PMMA layer over centimeter-sized CVD graphene film for the first time. No organic solvents are involved in the whole transfer process. The transferred graphene film is clean and intact over large area because of the cooperative effect of the capillary force and the van der Waals force which facilitates the conformal contact between graphene film and the substrate. Various types of graphene samples (i.e. monolayer, multilayer, and incomplete domains) can be easily transferred to diverse substrates including silicon wafer, sapphire, and quartz with good integrity. The transferred graphene film is of high cleanliness, and the graphene transistors show higher carrier mobility and lower level of p-type doping comparing to the conventional wet transfer technique.

Suppressing Interfacial Shunt Loss via Functional Polymer for Performance Improvement of Lead‐Free Cs2AgBiBr6 Double Perovskite Solar Cells

All‐inorganic lead‐free Cs2AgBiBr6 double perovskite solar cells (PSCs) have attracted growing attention owing to their eco‐friendly features and robust intrinsic stability. However, arising from the rapid crystal growth, the poor film quality always leads to substantial non‐radiative recombination and inferior performance improvement. Herein, high‐efficiency and stable Cs2AgBiBr6 PSCs are obtained by introducing a functional polymethyl methacrylate (PMMA) layer at the perovskite surface to avoid direct contact between carbon and the underlying charge transfer layer, as well as to passivate the defects. When assembling into solar cells, the non‐radiative charge recombination is suppressed and the interfacial charge extraction is accelerated. As a result, the carbon‐electrode‐based Cs2AgBiBr6 PSC yields an enhanced efficiency of 2.25% with a high open‐circuit voltage of 1.18 V. Moreover, the unencapsulated device exhibits superior long‐term stability owing to the protection of the PMMA layer from corrosion by the extraneous water and oxygen, retaining nearly 100% of the initial efficiency after storage in 25 °C, with 5% relative humidity (RH) for 80 days and high temperature of 85 °C, and 0% RH for 60 days, respectively. A simple method of polymer passivation for enhancing the performance and stability of Pb‐free Cs2AgBiBr6 PSCs is provided.

Transparent radiative cooling films containing poly(methylmethacrylate), silica, and silver

Window is the least energy-efficient part of buildings or cars; however radiative cooling, as an efficient energy-zero technology, is rarely used in window films of buildings or cars. Therefore, we in this work fabricated a transparent dual-layer film for daytime radiative cooling, which contained a layer of polymethyl methacrylate (PMMA) uniformly mixed with modified silica nanoparticles (SiO2 NPs) and a layer of silver. The dispersion of the modified SiO2 NPs in PMMA was notably improved through in-site grafting PMMA, which resulted in a high transparency of the radiative cooling film even at a high filling fraction of SiO2 (20 wt%). Owing to the strong broadband IR absorbance/emittance (εAW = 94.3%) and high sunlight reflectance (ρ ≈ 50%), the dual-layer film possessed a high cooling capacity and could achieve an average temperature drop of 1.4 °C than pure PMMA film in the daytime outdoor cooling measurement. In the simulated automotive cooling test, the dual-layer film cooled the interior space up to 6 °C below ambient temperature during peak solar hours. The excellent optical property and cooling capability exhibit a promising application of building and car windows for cooling their interior spaces.

Whispering Gallery Mode Resonator Temperature Compensation and Refractive Index Sensing in Glucose Droplets.

Among the different types of photonic sensor devices, optical whispering gallery mode resonators (WGMRs) have attracted interest due to their high level of sensitivity, small size, and ability to perform real-time temperature measurements. Here we demonstrate the applicability of temperature measurements using WGMR in both air and liquid environments. We also show that WGMR allowed measurements of the refractive index variations in an evaporating glucose–water solution droplet. The thermal tuning of WGMR can be reduced by coating WGMRs with a thin layer of polymethyl methacrylate (PMMA). Dip-coating the silica microsphere multiple times significantly reduced the resonance shift, partially compensating for the positive thermo-optical coefficient of silica. The shift direction changed the sign eventually.

Controllable refractive index sensing and multi-functional detecting based on the spin Hall effect of light.

In this work, based on the spin Hall effect of light (SHEL), by considering the surface plasmon resonance (SPR) effect, a multi-functional detecting and controllable refractive index (RI) sensing structure containing sodium is theoretically established. The results reveal that the sodium layer has great influence on transverse shift (TS) of SHEL, while the polymethyl methacrylate (PMMA) layer has a large impact on the resonance angle. In the symmetrical distribution of TS, sodium has obvious advantages over gold and silver in the TS and sensitivity. The quantitative relationship between the TS and the RI of the sensing medium is established. Fermi energy, thicknesses of PMMA and sodium can be adjusted to measure the RI of three different orders. Remarkably, the sensitivity can be controlled by changing the thickness of sodium. The structure can also be used to measure the resonance angle and Fermi energy. Therefore, besides the advantages of sodium, this work realizes controllable sensing of RI and the functions of resonance angle and Fermi energy detecting. These studies may open avenues for the application of optical RI sensors and the precision measurement of other physical quantities.

Enhanced One-Photon and Two-Photon Amplified Spontaneous Emissions of CsPbBr3 Thin Films by Insulating Polymer Coating

Lead halide perovskite is an attractive candidate for fabricating low-cost one-photon and two-photon-pumped lasers. However, the presence of vast trap sites and the leakage of electric fields limit the efficient amplified spontaneous emission (ASE) performances. Herein, we show that incorporating an insulating polymethylmethacrylate layer with a proper thickness onto perovskite films can play an important role in not only reducing both one-photon and two-photon ASE thresholds but also improving the light exposure stability remarkably. By means of spectroscopic investigation and optical simulation, the enhancement was ascribed to the trap passivation and electric field restraint and improved light outcoupling due to the dielectric confinement by the formation of symmetric waveguides structure. This work indicates the possibility of simple and effective approaches to realize efficient ASE and lasing.

Characterizing and Optimizing Piezoelectric Response of ZnO Nanowire/PMMA Composite-Based Sensor.

Due to the outstanding coupling between piezoelectric and semiconducting properties of zinc oxide nanowires, ZnO NW-based structures have been demonstrating promising potential with respect to their applicability in piezoelectric, piezotronic and piezo-phototronic devices. Particularly considering their biocompatibility and biosafety for applications regarding implantable medical detection, this paper proposed a new concept of piezoelectric composite, i.e., one consisting of vertically aligned ZnO NW arrays and an insulating polymer matrix. First, the finite element method (FEM) was employed to drive optimization strategies through adjustment of the key parameters such as Young’s modules and the dielectric constant of the dielectric constituents, together with the density and dimension of nanowire (NW) itself. Second, to investigate the functionality of each individual layer of composite, different designed structures were fabricated and characterized in terms of electrical and piezoelectric properties. Next, experimental and simulation tests were performed, indicating that the decreasing thickness of the top poly(methyl methacrylate) layer (PMMA) can substantially enhance the piezoelectric sensitivity of the ZnO NW composite. Besides the further benefit of no polarization being needed, our material has a comparable charge coefficient (d33) with respect to other lead-free alternatives (e.g., BaTiO3), confirming the high sensing abilities of the developed structure based on vertically aligned ZnO NW arrays. Finally, a time-varying model combining piezoelectricity and electric circuit modules was investigated in detail, giving rise to an estimation of the d33 coefficient for ZnO NWs. Based on this study, the developed material is revealed to be highly promising in medical applications, particularly regarding the FFR technique, where coronary pressure can be measured through a piezoelectric sensor.

PMMA sacrificial layer based reliable debonding of ultra-thin chips after lapping

Ultra-thin chips (UTCs) are needed to meet the performance and packaging related requirements of flexible electronics and 3D integrated circuits (ICs). However, handling of UTCs (<50 μm thick), particularly after thinning, is a challenging task as the excessive mechanical stresses could lead to cracking. Such damages could be prevented by restricting the stresses to acceptable levels. Herein, we present a new reliable and cost-effective method based on a polymethylmethacrylate (PMMA) sacrificial layer (20 μm-thick). The PMMA layer results in 4 order of magnitude lower stress on UTCs and, as a result, the reliable removal or debonding of UTCs (35 μm-thick) from the glass substrate has been achieved. The distinctive features of the presented method are high reliability and cost-effectiveness (an order of magnitude cheaper) with respect to conventional methods that use UV curable tapes. The UTCs with metal-oxide-semiconductor capacitors (MOSCAPs) devices were also obtained using this approach and were evaluated under different bending conditions. The stable and uniform performance (134 pF) observed under bending conditions demonstrates that the presented technique could be useful for integration of high-performance flexible UTCs on flexible printed circuit boards for various practical application.