Poly Methyl Methacrylate Films Research Articles

Impact of vacuum ultraviolet photons on ultrathin polymethylmethacrylate during plasma etching

State-of-the-art extreme ultraviolet lithography requires the use of ultrathin photoresists (or resists) due to pattern stability concerns and reduced depth of focus of the extreme ultraviolet lithography scanners. Current resists for extreme ultraviolet lithography are less than 50 nm thick. These ultrathin resists further complicate pattern transfer as unintended plasma-induced damage during dry etching is more pronounced. A better understanding of the interaction of plasma species with ultrathin resists is critical for enabling pattern transfer of sub-10 nm features. Here, we study the impact of vacuum ultraviolet photons, argon ions, and argon plasma on a 40 nm thick polymethylmethacrylate film. Using a deuterium lamp, an industrial ion beam etch tool, and an industrial inductively coupled plasma etch tool, we exposed the polymer to photons, ions, and plasma, respectively. The exposed samples were then analyzed for chemical and physical changes using different characterization techniques. It was observed that the vacuum ultraviolet photons interact with the entire bulk of polymer film, while the ions only affect the surface and subsurface region. The photon exposed samples formed smaller polymer fragments at low exposure doses and further started to cross-link at high doses. In contrast, the ion modification leads to carbonization of only the top few nanometers of the polymer film, leaving the bottom bulk intact. The plasma exposed sample showed changes characteristic to both vacuum ultraviolet photons and ions and their synergism. It was stratified with a 1.34 ± 0.03 nm thick ion-caused carbonized layer on top of a 13.25 ± 0.12 nm photon-induced cross-linked layer. By studying the impact of plasma photons on ultrathin polymethylmethacrylate, we were able to establish a baseline for a testing methodology that can be extended to novel ultrathin resist platforms.

Hot-press melt-assembly anisotropic porous structure with enhanced radiative cooling

Passive daytime radiative cooling (PDRC) is a promising and sustainable technology, achieving subambient cooling of objects without electrical consumption. Current PDRC designs realize efficient cooling performance, but their complicated and expensive fabrication approaches remain a challenge. Herein, we present a simple, versatile, and effective morphology control method based on the hot-press melt-assembly approach for fabricating tunable anisotropic porous polymethyl methacrylate (PMMA) films with high-efficiency daytime radiative cooling capability. The abundant and disordered micro/nanopores in the PMMA films caused by localized melting and bonding of particles reinforce scattering of the incident sunlight. Apart from the high refractive index contrast between PMMA and air within the porous structure, the dispersed PMMA particles exhibit an apparent micro/nanoplatelet morphology after hot pressing, enhancing the backscattering of sunlight within a porous PMMA film and contributing to the high-performance subambient radiative cooling. Therefore, the porous PMMA film features an ultrahigh solar reflectance of 0.95 and strong mid-infrared thermal emittance of 0.93, allowing for a peak subambient cooling temperature reduction of 9.9 °C under a solar irradiance of 700 W/m2 with an average radiative cooling power of 98 W/m2 during the daytime. Furthermore, the hot-press melt-assembly method is a cost-effective and high-efficient process for fabricating the desirable micro/nanoporous structure, providing a practical and effective pathway toward a large-scale production for excellent passive radiative cooling.

A simple and economic method to modify large organic surfaces for enhancing adhesion and transparent Au/PMMA with high electromagnetic shielding efficiency

This study introduces a simple and cost-effective approach for modifying large organic surfaces, facilitating robust adhesion between Au films and polymethyl methacrylate (PMMA) while retaining transparency to visible light and effectively shielding against electromagnetic interference (EMI). The proposed surface modification method employs a cheap low-power conventional UV lamp to illuminate organic surfaces in an open environment, rending it convenient and applicable for surfaces ranging from small to massive, irrespective of size, shape and location. By subjecting transparent PMMA glass to a brief 20–30 min exposure to a 36 W UV lamp positioned 5 cm away from the sample surface, the PMMA surface is dramatically modified and the surface is turned from hydrophobic to hydrophilic, establishing a strong adhesion between PMMA and Au films. The resulting Au/PMMA glass exhibits remarkable transparency about 70% within the visible light spectrum, coupled with an impressive EMI shielding efficiency that surpasses 20 dB across a broad range of electromagnetic wavebands, encompassing the S, C, X and Ku bands that correspond to the wave frequencies of major electromagnetic pollution and crucial applications of 5G communication, credit card validation, radar systems, traffic control, etc. Various characterizations have been conducted, elucidating the underlying mechanisms. This study presents an important advancement, and the accessible and scalable nature of the large-scalable surface modification method has far-reaching implications across numerous industrial sectors and applications, in addition to transparent EMI shielding Au/PMMA glasses.

Characterizing the thickness and temperature dependence of elastic modulus in polymer films using picosecond ultrasonics

Abstract Polymer nanofilms have found extensive applications in fields such as medical science and microelectronics, making the exploration of their mechanical properties highly significant. In this study, we examine the dependency of the out-of-plane elastic modulus of polymer films on both thickness and temperature, utilizing picosecond ultrasonics. Multiple acoustic modes of a polymer film are employed to measure its elastic modulus with heightened precision. Measurements are conducted on samples with different thicknesses and at different temperatures. The results indicate that the modulus of polymer nanofilms strongly depends on both thickness and temperature. For polymethyl methacrylate (PMMA) films with a thickness of less than 81 nm, the modulus determined exhibits a decrement correlating with thickness and is quantifiably inferior to the analogous bulk value. Additionally, as the temperature rises, the elastic modulus declines at clearly varying rates, which are described by two distinct modulus-temperature coefficients.

Photothermal spectroscopy on-chip sensor for the measurement of a PMMA film using a silicon nitride micro-ring resonator and an external cavity quantum cascade laser

Abstract Laser-based mid-infrared (mid-IR) photothermal spectroscopy (PTS) represents a selective, fast, and sensitive analytical technique. Recent developments in laser design permits the coverage of wider spectral regions in combination with higher power, enabling for qualitative reconstruction of broadband absorption features, typical of liquid or solid samples. In this work, we use an external cavity quantum cascade laser (EC-QCL) that emits in pulsed mode in the region between 5.7 and 6.4 µm (1770–1560 cm−1), to measure the absorption spectrum of a thin film of polymethyl methacrylate (PMMA) spin-coated on top of a silicon nitride (Si3N4) micro-ring resonator (MRR). Being the PTS signal inversely proportional to the volume of interaction, in the classical probe–pump dual beam detection scheme, we exploit a Si3N4 transducer coated with PMMA, as a proof-of-principle for an on-chip photothermal sensor. By tuning the probe laser at the inflection point of one resonance, aiming for highest sensitivity, we align the mid-IR beam on top of the ring’s area, in a transversal configuration. To maximize the amplitude of the photoinduced thermal change, we focus the mid-IR light on top of the ring using a Cassegrain reflector enabling for an optimal match between ring size and beam waist of the excitation source. We briefly describe the transducer design and fabrication process, present the experimental setup, and perform an analysis for optimal operational parameters. We comment on the obtained results showing that PTS allows for miniaturized robust sensors opening the path for on-line/in-line monitoring in several industrial processes.

Doping a highly charged, water-soluble lanthanide complex into a hydrophobic polymer for the preparation of luminescent films

Doping a highly charged water-soluble complex in a hydrophobic polymethyl methacrylate (PMMA) to form transparent film is demonstrated with using a heptaanionic tri-TbIII complex of thiacalix[4]arene-p-tetrasulfonate (TCAS), formulated as Tb3TCAS2. A bulky hydrophobic countercation, trihexyl(tetradecyl)phosphonium (THTDP+), enabled the isolation of the Tb3TCAS2 salt, which was soluble in a PMMA solution in chloroform. The drop casting of a polymer solution containing 10 wt% THTDP–Tb3TCAS2 salt yielded a transparent film with energy-transfer luminescence. Near-infrared emitting films with Yb3TCAS2 and Nd3TCAS2 were also prepared. The luminescence lifetime (τ) (1.15 ms) of 1.0 wt% Tb3TCAS2-doped PMMA films surpassed that of the salt (0.924 ms), while the luminescence quantum yield (Φ) of the film (0.17) was smaller than that of the salt (0.33). DMSO was the suitable solvent for the salt, providing longer τ (1.40 ms) and larger Φ (0.44) at 0.50 wt%. A low salt concentration in PMMA resulted in a long lifetime. Spin-coated films had longer lifetimes (1.47 ms) at 1.0 wt% owing to a solution-like PMMA environment preventing Tb3TCAS2 aggregation. Drop-casted films had larger Φ values than spin-coated films, as the former might contain salt-like Tb3TCAS2 aggregates.

PRACTICAL APPLICATION OF A FRACTIONAL FACTOR EXPERIMENT FOR ASSESSING THE INFLUENCE OF FACTORS ON THE SENSITIVITY OF A CAPACITIVE HUMIDITY SENSOR OF A TWO-LAYER STRUCTURE

The work uses a fractional factorial experiment in order to reduce the number of experiments. Capacitive humidity sensors of a two-layer structure made on a sitall substrate served as experimental samples. Hygroscopic salt NaCl was used to create a moisture-sensitive layer that would perform the function of a dielectric. Solutions of this salt with concentrations of 0,89 mol/l and 5,33 mol/l were applied by spraying on the surface of capacitive humidity sensors with thicknesses of 5,0 μm and 10.0 μm. In order to prevent the drop of the dew point, a protective layer was created − it is a moisture-absorbing polymethyl methacrylate film with thicknesses of 40 μm and 80 μm. According to the Cochrane’s test, it is proved that the fractional factorial experiment is reproducible. Using regression analysis, a quantitative assessment of the influence of factors on the sensitivity of the capacitive humidity sensor of the two-layer structure was carried out. Based on the developed regression equation, it was established that the concentration of the NaCl salt solution significantly affects the sensitivity of the capacitive humidity sensor of the two-layer structure. Significant coefficients of the regression equation were determined using the Student's test. Adequacy of the adjusted regression equation to the results of the factorial experiment was proved using Fisher's test. Based on the regression equation on the scale of real factors, which contributes to the optimization of the humidity sensor manufacturing parameters, it was established that the sensitivity of the capacitive humidity sensor of the two-layer structure depends on such factors as the thickness of the protective layer and the concentration of the NaCl salt solution. However, the sensitivity of the capacitive humidity sensor of the two-layer structure is significantly affected by the concentration of the hygroscopic NaCl salt solution. The highest sensitivity of 2,46 nF/% is provided with the following optimal parameters of the manufacturing process of the capacitive humidity sensor of the two-layer structure: the concentration of the hygroscopic NaCl salt solution is 5,33 mol/l, the thickness of the protective layer is 80 μm. Considering that the thickness of the moisture-sensitive layer does not significantly affect the sensitivity of the capacitive humidity sensor, the thickness of this layer can be taken in the range from 5,0 μm to 10,0 μm.

Influence of Congored on the Optical, Dielectric and Thermal Behavior of Polymethyl Methacrylate and Polyvinyl Chloride

Polymethyl methacrylate (PMMA)/Congo Red (CR) and polyvinyl chloride (PVC)/CR composite films were prepared on optical glass by the drop method for optical measurements and also prepared as tablets under pressure for dielectrical measurements. The optical transmission spectra measurements for PMMA and PVC film doped with CR showed a highly absorption in the ultraviolet-visible (UV-Vis) optical range (at 353 nm and 518 nm) and considerably blocking in broad visible range (190 nm–640 nm). PMMA/CR and PVC/CR composite films containing congo red at a concentration of 1 wt% showed maximum absorption bands at 290 nm and 416 nm, but their transmittance percentages were reasonably reduced compared to those of pure PMMA and PVC. Both of composites indicated high transmittances between 640 nm and 800 nm. The optical constants of the PMMA/CR and PVC/CR composite films such as optical band energy gaps (Eg) estimated using Tauc’s model, refractive index and reflectance (%) were calculated. UV–Vis, Fourier transform infrared spectroscopy (FTIR) and Thermogravimetry Analysis (TGA) measurements were used to confirm the breakdown of the -N = N- azo group bonds attached to the aromatic ring as a result of thermal decomposition of CR at 500 °C, and it was suggested that N2 gas was eliminated from the CR above 360 °C. The dielectric plots showed that the dielectric constant increased when the CR is doped up to 70 wt% in the polymer matrices. A further increase in the doping concentration of CR resulted in an increase of the dielectric constant. The dielectric constant decreased with an increase in the frequency for all of the samples. The ac (alternating current) conductivity values of PMMA and PVC showed an increase with increasing CR dopant in the polymer composites, while the ac conductivity values were found to be values between those of the pure polymers and CR.

Investigation of optical properties of nanoparticle-dispersed polymer films

Composite films of polystyrene and polymethyl methacrylate with added ZnO and ZrO2 nanoparticles have been prepared. Effective medium approximations have been applied to calculate final refractive indices. Results are compared to the experimental values of films with different thickness. Transparency of neat polymer and nanocomposite layers is also studied.

A skin-wearable and self-powered laminated pressure sensor based on triboelectric nanogenerator for monitoring human motion

Flexible and skin-wearable triboelectric nanogenerators (TENGs) have emerged as promising candidates for self-powered tactile and pressure sensors and mechanical energy harvesters due to their compatible design and ability to operate at low frequencies. Most research has focused on improving tribo-negative materials for flexible TENGs, given the limited options for tribo-positive materials. Achieving biocompatibility while maintaining the sensitivity and capability of energy harvesting is another critical issue for wearable sensors. Here, we report a TENG-based biocompatible and self-powered pressure sensor by simple fabrication of layer-by-layer deposition methods. The Laminated Flexible-TENG comprises polytetrafluoroethylene (PTFE) and polymethyl methacrylate (PMMA) films embedded within a flexible and biocompatible polydimethylsiloxane (PDMS) matrix. A nanostructured PDMS surface obtained by oxygen plasma facilitated the sputter deposition of a layered indium tin oxide copper electrode and a tribo-positive PMMA thin layer on top. The addition of the indium tin oxide layer to copper significantly improved the quality and performance of the indium tin oxide-copper electrode. Self-powered Laminated Flexible-TENGs demonstrated impressive pressure-sensing capabilities, featuring dual sensitivity of 7.287 V/kPa for low pressure and 0.663 V/kPa for higher pressure. Moreover, the PDMS-encapsulated TENG sensor effectively traced the physiological motions, such as wrist and finger bending, and efficiently harnessed the waste energy from everyday physical activities, such as walking and jogging. The maximum peak-to-peak voltages of 18.3 and 57.4 V were recorded during these motions. Encapsulated TENGs have broad potential in wearable technology, including healthcare, human-machine interfaces, and energizing microelectronics.

Engineering Tunable Ratiometric Dual Emission in Single Emitter-based Amorphous Systems.

Molecular emitters with multi-emissive properties are in high demand in numerous fields, while these properties basically depend on specific molecular conformation and packing. For amorphous systems, special molecular arrangement is unnecessary, but it remains challenging to achieve such luminescent behaviors. Herein, we present a general strategy that takes advantage of molecular rigidity and S1 -T1 energy gap balance for emitter design, which enables fluorescence-phosphorescence dual-emission properties in various solid forms, whether crystalline or amorphous. Subsequently, the amorphism of the emitters based polymethyl methacrylate films endowed an in situ regulation of the dual-emissive characteristics. With the ratiometric regulation of phosphorescence by external stimuli and stable fluorescence as internal reference, highly controllable luminescent color tuning (yellow to blue including white emission) was achieved. There properties together with a persistent luminous behavior is of benefit for an irreplaceable set of optical information combination, featuring an ultrahigh-security anti-counterfeiting ability. Our research introduces a concept of eliminating the crystal-form and molecular-conformational dependence of complex luminescent properties through emitter molecular design. This has profound implications for the development of functional materials.

Engineering Tunable Ratiometric Dual Emission in Single Emitter‐based Amorphous Systems

AbstractMolecular emitters with multi‐emissive properties are in high demand in numerous fields, while these properties basically depend on specific molecular conformation and packing. For amorphous systems, special molecular arrangement is unnecessary, but it remains challenging to achieve such luminescent behaviors. Herein, we present a general strategy that takes advantage of molecular rigidity and S1‐T1 energy gap balance for emitter design, which enables fluorescence–phosphorescence dual‐emission properties in various solid forms, whether crystalline or amorphous. Subsequently, the amorphism of the emitters based polymethyl methacrylate films endowed an in situ regulation of the dual‐emissive characteristics. With the ratiometric regulation of phosphorescence by external stimuli and stable fluorescence as internal reference, highly controllable luminescent color tuning (yellow to blue including white emission) was achieved. There properties together with a persistent luminous behavior is of benefit for an irreplaceable set of optical information combination, featuring an ultrahigh‐security anti‐counterfeiting ability. Our research introduces a concept of eliminating the crystal‐form and molecular‐conformational dependence of complex luminescent properties through emitter molecular design. This has profound implications for the development of functional materials.

Laser-assisted direct roller imprinting of large-area microstructured optical surfaces

In this study, a high-throughput fabrication method called laser-assisted direct roller imprinting (LADRI) was developed to lower the cost of nanoimprinting large-area polymer films and to address problems associated with nanoimprinting, namely, microstructural damage and precision in flatness of entire film. With LADRI, the laser directly heats the microstructured surface of the roller mold, which heats and melts the surface of a polymethyl methacrylate (PMMA) film to replicate the microstructures on the mold rapidly. In this study, the effects of laser power density, scanning speed, size of the microstructures, and contact pressure on the replication speed were investigated experimentally. The replication speed increased as the power and scanning speed increased. However, because the film required heating until it filled the entire depth of the microstructure, an appropriate replication speed was necessary. This result was supported by simulation of the temperature distribution inside the mold and the PMMA using transient heat conduction analyses. To demonstrate the applications of LADRI, two different optical surfaces were replicated: an antireflection (AR) structure with conical structures sized several hundred nanometers and a light-extraction structure with a microlens array (MLA) comprising 10 μm lenses, for display and illumination, respectively. The replication degree of the MLA was governed by the contact pressure. Polymer flow simulation indicated that the heat conduction and flow speeds of the melted PMMA surface were comparable within several tens of micrometers. In addition, the reflectivity of the AR structure decreased from 4 to 0.5%, and the light intensity of the light-extraction structure increased by a factor of 1.47.

Studies on the structural and magnetic properties of PMMA/Ni nanocomposite system prepared by embedding Ni nanoparticles in the PMMA films

PMMA/Ni nanocomposite films have been prepared by embedding Ni nanoparticles and maintaining their different thickness (5–50 nm) in PMMA (polymethylmethacrylate) film matrix by using ion beam sputtering (IBS) technique. Grazing incidence x-ray diffraction (GIXRD) results reveal Ni is present in metallic form in the FCC phase. X-ray reflectivity (XRR) is used to measure the nominal thickness of the Ni nanoparticle layer. Surface morphology was studied using atomic force microscopes (AFM). SXAS (soft x-ray absorption spectroscopy) studies on PMMA/Ni nanocomposites were done using synchrotron radiation to understand the electronic structure of these films which reveals that Ni is present in metallic state confirming that PMMA as host matrix protects the magnetic Ni nanoparticles from external oxidation. The magneto-optical Kerr effect (MOKE) magnetometer and MOKE microscope were employed to study the magnetic properties and simultaneously record the real time evolution of magnetic domains at 0°, 45°, and 90° azimuthal angles. All films show soft ferromagnetic behaviour and all the films show isotropic behaviour except one with Ni nanoparticle layer thickness of 40 nm. MOKE micrographs witness the gradual growth of magnetic domains with increase in thickness of Ni nanoparticle layer. These PMMA/Ni nanocomposite films may be viewed as potential candidate for futuristic functional material.

Computational and experimental study on the resistance welding process of a glass fiber‐reinforced epoxy‐based composite with thermoplastic interlayer adherent

AbstractIn this work, resistance welding of a glass fiber‐reinforced epoxy composite (GFRC) was studied with numerical optimization and experimental validation. A steel mesh and polymethyl methacrylate (PMMA) films were used as the heating element and adherent interlayers, respectively. A transient heat transfer module was implemented to conduct the parametric optimization study, with variables of electricity power, clamping distance and weld time. The optimal welding condition was then confirmed as 20 W, 0.4 mm and 30 s, with a melting degree of 95.2%. A thermal meter and a thermal camera validated the simulated temperature results. Welding quality was experimentally characterized by single lap shear tests and scanning electron microscopy (SEM). The highest lap shear strength of 3.8 ± 0.3 MPa was captured on the specimen welded with the optimized condition. This was 76% that of the benchmark made with the adhesive bonding method but it was over 200 times faster.Highlights Resistance welding of GFRC with PMMA films and a steel mesh is studied with FEA. Simulation results are quantitatively validated with experimental methods. Optimal welding conditions are confirmed in association with welding tests.

Stabilities of bis(thienyl)ethenes in polymethyl methacrylate (PMMA) coatings as absorbance modulation layers for nanoscale imaging

Stabilities of substituted BTEs in PMMA films are described which differ from those in solution.

Terahertz surface plasmon polariton resonant sensing method based on grating coupled InSb

A grating coupled terahertz (THz) surface plasmon polariton (SPP) resonant biochemical sensing structure is designed and simulated, which is formed by etching submillimeter gratings on the surface of indium antimonide (InSb) substrate. The simulation results based on the phase matching equation show that when the TM polarized THz parallel beam is illuminated into the grating interval at a 30° incidence angle, the ± 1 order THz diffraction beam of the grating can excite low-frequency SPP and high-frequency SPP with opposite propagation directions, respectively. The commercial THz time-domain spectroscopy (TDS) devices can be used to accurately measure the low-frequency SPP easily. So, the dependence of the resonance characteristic and sensing characteristic of low-frequency SPP on grating structural parameters is systematically simulated and analyzed in this work. The simulation results indicate that the InSb grating bare sensing chip cannot provide a detectable response to the tyrosine monolayer adsorption layer. The reason for this is that the penetration depth of the low-frequency SPP evanescent field is much greater than the thickness of the tyrosine adsorption layer, resulting in insufficient interaction between the two. In order to detect biomolecules, the sensitization method of InSb grating covered with porous film is simulated and analyzed in this work. Porous film has a molecular enrichment effect, which can extend the interaction between THz surface wave and biological target from a single molecule scale to the entire film thickness, thereby improving the biological detection sensitivity of the sensor. The simulation results show that taking tyrosine for example, when the InSb grating surface is covered with a porous polymethyl methacrylate (PMMA) film with a thickness of 120 μm and a porosity of 0.4, its adsorption sensitivity is 0.39 THz/unit volume fraction.

Construction and fine tuning of host-guest doping systems and the underlying mechanism of room temperature phosphorescence

To obtain ultralong and efficient pure organic room temperature phosphorescent materials, as well as explore the intrinsic mechanisms affecting the phosphorescence performance of host-guest doping systems, two carbazole derivatives with the same molecular structure, named as L-CzIPCN and CzIPCN, were prepared by using carbazole synthesized in the laboratory and commercial carbazole. By choosing L-CzIPCN/CzIPCN and polymethyl methacrylate (PMMA)/polyvinyl alcohol (PVA)/benzophenone derivatives (BP, F-BP, Br-BP, and DF-BP) as the guest and host respectively, a series of new doping systems were constructed, and optimized by tuning doping ratios between host and guest materials. Among of them, F-BP/L-CzIPCN shows the longest room temperature phosphorescence (RTP) lifetime (501.23 ms), with RTP quantum yield of 31.19 %, followed by 0.2 % L-CzIPCN@PVA film (221.66 ms, 5.86 %) and 0.2 % L-CzIPCN@PMMA film (102.73 ms, 4.28 %) respectively. Moreover, L-CzIPCN displays different RTP spectra in diverse hosts, with dual-band RTP emission at 550 nm and 600 nm in benzophenone derivatives, but single RTP emission maxima in PMMA films, as well as a main emission peak at 470–510 nm and a shoulder peak at 550–590 nm in PVA films. The UV–Vis absorption spectra, fluorescence and phosphorescence spectra, and theoretical calculations indicate that RTP comes from the guest monomers in benzophenone derivatives/L-CzIPCN doping systems, with local triple characteristics, and host materials with large dipole moment, appropriate T1 energy level, and small energy gap between S1 and T1 contribute to improving RTP performance of the doping systems. Based on the excellent luminescence and different RTP lifetimes of the doping systems, some high-level anti-counterfeiting, and information encryption patterns were successfully constructed.

Thermoplastic film materials for damping in mechanical engineering

   An effective way of damping engineering structures is to use elements formed by a combination of hard and soft alternating layers. The outer rigid layers, made of structural materials, take up force infl uences, while the soft layers of viscoelastic polymers provide energy dissipation of the layered structure. The paper summarizes the results of research on the development of thin thermoplastic fi lms of plasticized polyvinyl acetate, polybutylmethacrylate and polymethylmethacrylate which have ultra-high dissipative properties and are used as a vibration-absorbing component of composite structures. It is shown that high damping properties are realized in fi lms with thickness of 0.1 –0.05 mm, which makes it possible to obtain two- and three-layer vibration-absorbing films with an extended temperature interval of effective damping in the metal-polymer-metal structures.

Promoting organic room temperature phosphorescence through in situ polymerization

AbstractOrganic room temperature phosphorescence materials (RTP) have attracted much attention for their wide application in organic light‐emitting diodes, anti‐counterfeiting, and sensors. In this work, a series of organic luminogens containing carbonyl and aromatics were fixed in a three‐dimensional polymethyl methacrylate (PMMA) network by in situ polymerization. All organic luminogens‐doped in situ PMMA (s‐PMMA) columns achieved longer RTP lifetimes than those of doped commercial PMMA (c‐PMMA) films, especially, the RTP lifetime of NMP2O in these PMMA matrixes increased from 1.82 ms to 156.34 ms by about 86 times. It is mainly due to the restriction of molecular motions by highly entangled polymer chains and rigid environments to efficiently inhibit the non‐radiative transitions. Also, the excellent shielding effect toward oxygen by the in situ polymerization process can avoid possible quenching effects on triplet excited states, beneficial to RTP emission. Thus, it affords an efficient approach to achieving persistent RTP for three‐dimensional displaying applications.