Poly Methyl Methacrylate Films Research Articles

Molecular design of −substituted boron difluoride curcuminoids: Tuning luminescence and nonlinear optical properties

Boron β-diketonates are prospective fluorescent dyes for functional organic materials to new technologies in the fields of chemistry, NLO-optics, photonics and bio-imaging. The novel NIR-to-NIR luminophors – curcuminoids of boron difluoride with different substituents at the central carbon atom (at the γ-position) of the chelate ring 1,7-bis(4′-N,N′-dimethylaminophenyl)-4-organyl-gept-1,6-dien-3,5-dionate of boron difluoride (1–5) were synthesized. Luminescence in solutions, crystals and polymer matrices, photobiological properties and NLO properties in polystyrene (PS) and polymethylmethacrylate (PMMA) were studied. The crystal structure has been determined for 1. For 1–5, in PS film, upon excitation by laser (365 nm), two luminescence bands are observed in the blue (430 nm) and red (650–700 nm) regions of the spectrum. For 1–5, two-photon luminescence is recorded in PS and PMMA films. PS 1 films demonstrate high photostability. The synthesized dyes turned out to be almost non-toxic for HCT116 tumor cells both in a long-term dark experiment (72 h) and after photoexcitation in accordance with absorption maxima in the submicromolar concentration range. The compounds were rapidly accumulated by cells within 3 h, demonstrating cytoplasmic distribution and the potential for use as cellular photoimaging agents. The accumulation of dyes with hydrocarbon γ-substitutes (methyl, iso-propyl, phenyl) after 3 and 24 h is more effective compared to dye 2 (commercial product Cranad-2).

Photocurable Hypervalent Fluorinated Sulfur Containing Thin Films with Remarkable Hardness and Modulus.

Novel tetrafluoro-λ6-sulfanyl-containing oligomers prepared by visible light-promoted addition of 1,4-(bis-chlorotetrafluoro-λ6-sulfanyl) benzene or 1,3-(bis-chlorotetrafluoro-λ6-sulfanyl) benzene to either 1,4-diethynyl benzene or the 1,3-diethynyl isomers form hard, stress resistant thin films on spin casting. The isomeric oligomers were utilized to establish a structure-function relationship for the mechanical properties of films prepared from the oligomers. The Young's moduli of 145-nm-thick cured films could reach 60 GPa. The measured hardnesses, between 1.57 and 2.77 GPa, were more than double those of polymethyl methacrylate (PMMA) films. Curing of the tetrafluoro-λ6-sulfanyl-containing polymer films by UV irradiation resulted in coatings that exhibited remarkable hardness and modulus with good surface adhesion to silicon.

Impressive nonlinear optical response of π-conjugated, photoluminescent soft nanoparticles in polymer matrix

Nonlinear optical (NLO) materials are useful for applications varying from modulation of optical signals to cancer therapy. Besides inorganic crystals and organic molecules with defined structures, carbonized products have emerged as a new generation of materials showing good NLO properties. Due to the small sizes, the NLO performance of such materials mainly originates from nonlinear absorption. Obtaining a product with a high content of π-conjugated moiety is the key to improving the NLO performance. By using aldehydes bearing π units as the precursors, in this work we synthesized three polymeric nanoparticles (PNPs) through one-step pyrolysis, which also have large contents of π-conjugated structures. It was found that a larger size of π unit in the precursor led to a higher content as well as the size of the π-conjugated structure, which induced a bathochromic shift in the emission and an improved performance in the NLO response. When embedded in polymethylmethacrylate films, the products showed reverse saturable absorption (RSA) behavior with β up to 4.20 × 10−6 m W−1 and optical limit threshold down to 0.0012 J cm−2, which are comparable to those of metal-doped counterparts. This work gives deep insight on the structure-property relationship of the pyrolyzed products from π-conjugated small molecules, which is also useful for the preparation of task-specific carbon dots (CDs) or PNPs in future.

Facile Fabrication of Hierarchical Structured Anodic Aluminum Oxide Molds for Large-Scale Production of Superhydrophobic Polymer Films.

Anodized aluminum oxide (AAO) molds were used for the production of large-area and inexpensive superhydrophobic polymer films. A controlled anodization methodology was developed for the fabrication of hierarchical micro-nanoporous (HMN) AAO imprint molds (HMN-AAO), where phosphoric acid was used as both an electrolyte and a widening agent. Heat generated upon repetitive high-voltage (195 V) anodization steps is effectively dissipated by establishing a cooling channel. On the HMN-AAO, within the hemispherical micropores, arrays of hexagonal nanopores are formed. The diameter and depth of the micro- and nanopores are 18/8 and 0.3/1.25 µm, respectively. The gradual removal of micropatterns during etching in both the vertical and horizontal directions is crucial for fabricating HMN-AAO with a high aspect ratio. HMN-AAO rendered polycarbonate (PC) and polymethyl methacrylate (PMMA) films with respective water contact angles (WCAs) of 153° and 151°, respectively. The increase in the WCA is 80% for PC (85°) and 89% for PMMA (80°). On the PC and PMMA films, mechanically robust arrays of nanopillars are observed within the hemispherical micropillars. The micro-nanopillars on these polymer films are mechanically robust and durable. Regular nanoporous AAO molds resulted in only a hydrophobic polymer film (WCA = 113-118°). Collectively, the phosphoric acid-based controlled anodization strategy can be effectively utilized for the manufacturing of HMN-AAO molds and roll-to-roll production of durable superhydrophobic surfaces.

Oleic acid-induced changes in the dynamic viscoelastic behavior of poly(methyl methacrylate) polymer film

This study investigates the impact of oleic acid on the dynamic viscoelastic behavior of polymethyl methacrylate (PMMA) polymer films. By incorporating oleic acid as a plasticizer, we aim to enhance the ductility and reduce the brittleness of PMMA. Dynamic mechanical analysis (DMA) was employed to assess changes in viscoelastic properties, revealing significant improvements in the flexibility and energy dissipation capacity of the PMMA films. The addition of oleic acid resulted in a noticeable shift in the glass transition temperature and a reduction in storage modulus, indicating enhanced polymer chain mobility. Raman and infrared spectroscopy confirmed the successful integration of oleic acid, highlighting its interaction with PMMA at the molecular level. Our findings demonstrate that oleic acid is an effective plasticizer for PMMA, providing valuable insights into the design of flexible and durable polymer-based materials for various applications.

Application of Cyrene solvent for the fabrication of polymethyl methacrylate, polyethyl methacrylate and composite films containing hydroxyapatite and diamonds

AbstractCyrene is a new biodegradable solvent, which represents a green alternative to many traditional toxic solvents for advanced polymers. Therefore, this investigation is motivated by interest in applications of Cyrene for polymer processing. The feasibility of solubilization of polymethyl methacrylate (PMMA) and polyethyl methacrylate (PEMA) in Cyrene is demonstrated. The ability to form relatively concentrated solutions of the high molecular mass polymers is an important factor for the formation of PMMA and PEMA films by a dip coating method. It was found that the polymer coatings provide corrosion protection of stainless steel in 30 g L−1 NaCl solutions. Another important finding is that the use of Cyrene facilitates the fabrication of stable suspensions of hydroxyapatite (HAp), microdiamond, and nanodiamond particles. Therefore, the problems of the dispersant selection for dispersion of chemically inert diamond and development of biocompatible dispersants are avoided using Cyrene. For the fabrication of composite films, HAp nanorods with reduced particle size are obtained using rutin as a chelating capping agent. Composite films containing HAp, microdiamond and nanodiamond in the PMMA or PEMA matrix are obtained. The composite films are promising for biomedical applications. It was found that the film morphology, composition and microstructure are influenced by the solvent–particle–polymer interactions and processing conditions.

Luminescence under UV(A, B and C) and sunlight exposure of tetrakis Tb3+ carboxylate complexes doped in different polymers

New tetrakis Lanthanide(III) carboxylate-based complexes (Ln3+: Eu and Tb) were successfully synthesized via a facile one-pot method with flufenamic acid (fluf) as ligand and benzimidazole (Bzim) or 1-ethyl-3-methylimidazole (C2mim) as counterions. In addition, the Q[Tb(fluf)4] complexes (Q+: Bzim and C2mim) were doped into polymethylmethacrylate (PMMA), polystyrene (PS), polycaprolactone (PCL) and poly(9-vinylcarbazole) (PVK) polymeric matrices at a 1 % (w/w) concentration and revealed highly desirable photophysical features such as wide range excitation wavelengths for the PMMA and PCL matrices and a very uncommon emission under sunlight exposure arising from the Tb3+ ion for the PMMA material. Thus, the tetrakis compounds with general formula Q[Ln(fluf)4] were characterized by elemental and thermal analysis, ESI-MS mass spectrometry, and FTIR absorption spectroscopy. The PMMA:(1 %)Q[Tb(fluf)4] doped films revealed higher thermal stability than the complexes. The tetrakis Eu3+ complex with Bzim as counterion shows no luminescence either for room or low temperature due to a highly operative low-lying ligand to metal charge transfer (LMCT) state quenching, while the corresponding C2mim-based analogous complex reveals some weak intensity emission, showing very low intrinsic quantum yield (QEuEu) values. On the other hand, the corresponding Tb3+ compounds presented bright green emission for the solid-state complexes and, particularly, for the PMMA:(1 %)Q[Tb(fluf)4] doped films when excited at UVA, UVB, and UVC radiation. Moreover, when the doped PMMA films are exposed to sunlight radiation in an open external environment, a bright green emission arising from the 5D4 → 7F5 transition from the Tb3+ ion can be seen. In this way, these optical results suggest that the PMMA:(1 %)Q[Tb(fluf)4] luminescent photonic materials can act as versatile and efficient light-converting molecular devices (LCMDs).

Cyclometalated Pt(II)C^N phosphors bearing a bis(diphenylphorothioyl) amide ligand: synthesis and photophysical properties

Six Pt(II) complexes bearing a primary phenylpyridine (ppy) ligand or a ppy derivative and two Pt(II) complexes bearing a primary 8-hydroxyquinoline (hqnl) or 7-bromo-8-quinolinol ligand have been prepared via coordination with an auxiliary bis(diphenylphosphothionyl) amide (HStpip) ligand. All eight complexes were characterized by NMR (1H,13C, and 31P), HRMS, and elemental analysis. In addition, complexes 2, 4, 5, and 8 were characterized by single crystal XRD. The eight complexes were not emissive in solution under N2 at room temperature (r.t.). However, they all exhibited an intense emission in the solid state and in 2 wt.% polymethyl methacrylate (PMMA) films. In particular, 5 bearing a primary 2-([1,1'-biphenyl]-3-yl)-4-phenylpyridine ligand exhibited a triplet emission at 525 and 552 nm with a quantum yield of 80% in pure solid state. Density functional theory (DFT) and time dependent (TD) DFT calculations were performed for optimization and predicting the excitation properties of 2, 4, 5, and 8. The computational results reveal that the intrinsic triplet emissions of 2, 4, and 5 are the result of combinations of ligand-to-metal charge transfer (LMCT) (π*(ppy) → d(Pt)) and ligand-to-ligand charge transfer (LLCT) (π*(ppy) → p(Stpip)), whereas the triplet emission of 8 shows a π*–π character with a small LMCT (π*(hqnl) → d(Pt)) component.

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.

A nanocomposite film with layer-by-layer self-assembled gold nanospheres driven by cucurbit[7]uril for the selective transport of l-tryptophan and lysozyme

Selective separation of amino acids and proteins is crucial in various areas of research, including proteomics, protein structure and function studies, protein purification and drug development, and biosensing and biodetection. A nanocomposite film is formed by combining layer-by-layer self-assembled gold nanospheres (AuNPs) driven by cucurbit[7]uril (CB[7]) and polymethyl methacrylate (PMMA) film. Due to the host-guest interactions, the selective transmission of l-tryptophan in the nanocomposite film is confirmed by the current-voltage measurements using a picoammeter. Furthermore, by adjusting the particle size of AuNPs to increase channel size, lysozyme containing multiple tryptophan residues can selectively pass through the nanocomposite film, indicating the high versatility and adaptability of the nanocomposite film. This study will provide a new direction for the selective separation of amino acids and proteins.

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.