PMMA Composite Films Research Articles

Sol-gel prepared TiO2 – PMMA composite thin film for high laser induced damage threshold optical coating

We report high-quality TiO2 and TiO2-PMMA composite thin films prepared by sol-gel process for application in optical coatings. The addition of PMMA to the TiO2 sol exhibits significant improvements in the optical quality and morphology of the TiO2 films. A comparison between TiO2 and TiO2-PMMA composite thin films is described with respect to various optical properties and their application in optical coatings for high-energy laser applications. The refractive index and bandgap of TiO2 are tailored by controlling the TiO2 sol: PMMA volume ratio. The refractive index varies in the range of 2.4 to 2.0 at 550 nm by controlling the TiO2: PMMA composition. Incorporation of PMMA leads to reduction in absorption from 1000 ppm to 20 ppm in the composite films, which is attributed to passivation of defect states. In addition, incorporation of PMMA into the TiO2 sol results in the filling of voids and a significant improvement in surface figure (from λ/6 to λ/10) of the composite films. These properties collectively enhance the laser induced damage threshold (LIDT) of 2.1 J/cm2 for TiO2 film to 17 J/cm2 of the TiO2-PMMA composite film. LIDT mechanisms in the films are discussed. Demonstration of antireflection coatings (AR) as well as high reflection coatings (HR) exhibiting wavelength tuning of the reflection peak using TiO2-PMMA composite thin films, is presented. An AR coating @1200 nm with 11.5 J/cm2 LIDT is reported.

Phototuning of Multi-Color Emission in PMMA Composite Films for Information Encryption Applications

A strategy centered on dynamically tunable excited-state proton transfer (ESPT) processes is proposed for the design and synthesis of luminescent compounds. An emitter based on guanidine-substituted 1,8-naphthalimide (R-1) with ESPT characteristics has been meticulously engineered. Upon incorporation into poly (methyl methacrylate) (PMMA) matrices, the tunable ESPT process, transitioning between blue and yellow-green emission within the composite film, can be precisely controlled through irradiation in different pH environments. Moreover, the luminescence of the R-1/PMMA composite film exhibits variations in response to environmental changes, and demonstrates excellent fatigue resistance. Exploiting this characteristic, information such as “2020” can be encoded, and this encoded information automatically manifests in response to fluctuations in external pH. Specifically, employing a designated method is essential for accurately deciphering the information. The pH-dependent nature of this feature imparts a higher level of security to the material and offers new insights into information encryption.

X-ray excited broadband blue emitting Lu2(1-x)Bi2xO3-PMMA thin films for high resolution imaging

In this paper, cubic-phase Lu2O3:Bi3+ nanoparticles, with a range of sizes between 110 and 180 nm, were obtained by a combination of co-precipitation and thermal annealing techniques. For these nanoparticles upon UV or X-ray excitation, strong broadband emission peaks at 410 and 480 nm corresponding to Bi3+ occupying S6 and C2 (Lu3+(S6) and Lu3+(C2)) sites, respectively, can be observed. On the basis of the concentration-dependent luminescence intensity ratios (I480(C2)/I410(S6)) of Bi3+(C2) to Bi3+(S6), the energy transfer from Bi3+(S6) to Bi3+(C2) can be confirmed at high Bi3+ concentration. In particular, their X-ray absorption coefficient, emission wavelength, afterglow level (60 ppm) and response time (465 ns) are almost comparable to those of the commercial Bi4Ge3O12 crystals. By the means of dispersing Lu1.98Bi0.02O3 nanoscintillators into organic polymer (PMMA)-acetone solution, the Lu1.98Bi0.02O3-PMMA flexible composite films exhibiting rapid response to X-ray photons, high X-ray sensitivity and radiation resistance, good mechanical performance and excellent environmental stability were prepared using a spin-coating technique. On the surface of X-ray imaging screen formed by the flexible dense composite films, the spatial resolution can reach to 6.0 lp/mm at a safe irradiation dose (4.6 μGy). Meanwhile, for the imaging screen using the flexible composite films after bended for thousands of times, we can observe clear image of each reed gap (300 μm) of the music box. For the Lu2O3:Bi3+-PMMA composite films, our results suggest that not only their scintillation properties are almost comparable to those of the commercial broadband Bi4Ge3O12 crystals, but also they might be applied in large-area and non-planar X-ray imaging.

Self-Supporting β-Ga2O3 Reinforced PMMA Composite Films with Multifunctional Traits

Self-Supporting β-Ga2O3 Reinforced PMMA Composite Films with Multifunctional Traits

CuInS2 Nanocrystals Embedded PMMA Composite Films: Adjustment of Polymer Molecule Weights and Application in Remote-Type White LEDs.

The commercial application of colloidal semiconductor nanocrystals has been realized owing to the development of composite film technology. Here, we demonstrated the fabrication of green and red emissive CuInS2 nanocrystals embedded polymer composite films of equal thickness by using a precise solution casting method. The impacts of polymer molecular weight on the dispersibility of CuInS2 nanocrystals were then systematically studied through evaluating the decrease in transmittance and red shift of emission wavelength. The composite films made from PMMA of small molecular weights exhibited higher transmittance. Applications of these green and red emissive composite films as color converters in remote-type light-emitting devices were further demonstrated.

Excellent Nonlinear Optical Limiting Behavior of Tetra (C60) Lanthanum Phthalocyanine in Solid Poly(methyl methacrylate) Films

This work reports on the exceptional optical limiting performance of a novel D–A-type compound, namely, LaPc-4(C60), wherein the lanthanide phthalocyanine is used as a donor and four C60 are used as acceptors. In addition, phenyl ether bonds were introduced into the molecule, making it semirigid and increasing its solubility. At the same time, the phenyl ether bond could act as a π-electron bridge, which increases the electron transfer pathway, expands the π-conjugated system, and reduces the spatial site resistance of the molecule. Furthermore, the uniform poly(methyl methacrylate) (PMMA) composite film (LaPc-4(C60)/PMMA) was prepared by a simple solution casting method. In comparison with individual C60 or LaPc(CHO)4, both LaPc-4(C60) in solution and in the solid PMMA composite film exhibited larger third-order nonlinear absorption coefficients and lower limiting thresholds at 532 nm. In particular, LaPc-4(C60)/PMMA exhibits huger nonlinear absorption coefficient (2900 cm/GW) and larger third-order susceptibility (4.91 × 10–9 esu), which can be attributed to the synergistic effect of the different non-linear absorption mechanisms and efficient photoinduced electron transfer process between C60 and LaPc.

Thermal and optical properties of PMMA films reinforced with Nb2O5 nanoparticles

The article presents the thermal and physical properties of PMMA composite films with the addition of Nb2O5 nanoparticles. The addition of nanoparticles to PMMA mainly influenced the optical transmission and glass transition temperature of composite films compared to pure PMMA. It is clearly visible in the results of the conducted ellipsometric and differential scanning calorimetry tests. X-ray studies showed that the heat treatment of the samples resulted in the ordering of the polymer structure (flattening of the polymer chains). Examining the surface of the samples with scanning electron microscopy, it can be seen that Nb2O5 nanoparticles formed unusual, branched formations resembling "snowflakes".

Optically Transparent and Toughened Poly(methyl methacrylate) Composite Films with Acylated Cellulose Nanofibers.

In this work, nanocomposites of poly(methyl methacrylate) (PMMA) with cellulose nanofiber (CNF) were prepared by a solution casting technique. CNF was modified by propionic anhydride (PA) to form surface-propionylated CNF (CNFp) to improve its compatibility with the PMMA matrix. CNF, CNFp, and acetylated CNF were compared with respect to their influence as fillers in PMMA composite films by ultraviolet–visible transmittance, haze values, tensile strength testing, and water contact angle measurement. It was demonstrated that 1 wt % of CNFp has good compatibility and uniform dispersion in the PMMA matrix, as demonstrated by the formation of a smooth surface composite film with good transparency, enhanced tensile properties, improved toughness, and lower wettability. Therefore, PMMA/CNFp composite films have great potential for use in several applications such as lightweight transparent materials, window substitutes, and see-through packaging.

Enhanced Performance of Pixelated Quantum Dot Light‐Emitting Diodes by Inkjet Printing of Quantum Dot–Polymer Composites

AbstractInkjet printing of colloidal quantum dots (QDs) is considered a promising technology for application in full‐color quantum dot light‐emitting diode (QLED) displays. However, QLEDs that are inkjet printed in a pixel‐defining bank structure generally exhibit a low performance, mainly due to the nonuniformity in its QD morphology. In this study, an enhanced performance of inkjet‐printing‐based pixelated QLEDs is achieved by introducing small amounts of poly(methyl methacrylate) (PMMA) of different molecular weights into QD inks. When this QD–PMMA composite ink is adopted, uniform droplets are formed, originating from contact line depinning during drying. Inside the bank structure, the inkjet‐printed QD–PMMA composite film shows a smooth surface and little pileup at the bank edges. A pixelated QLED with PMMA with a molecular weight of 8 kDa exhibits the highest luminance of 73 360 cd m−2 and an external quantum efficiency of 2.8%, which are remarkably higher than that of the inkjet‐printed QLED subpixels without PMMA. The result is verified through the observation of the drying process and the QLED subpixel shapes under operation. Thus, inkjet‐printed QD–PMMA composite inks can be a promising strategy for future research on pixelated QLEDs for the fabrication process of full‐color QLED displays.

Silica addition effect on optical properties of halide perovskite-PMMA composite film

The effect of silica (SiO2) addition on optical properties of organometal halide perovskite PMMA composite film was studied. The organometal halide perovskite, MAPbBr3, was synthesis using ligand assisted re-precipitation (LARP) method, and then was compose to PMMA and SiO2 directly to make composite films. The absorbances, transmittances, and photoluminescence (PL) spectrum of the samples were characterised using UV Vis and PL spectroscopy. The result shows that the addition of silica leads blueshift on photoluminescence and absorbance spectra. The blue shift reveals one-dimensional confinement effect in perovskite.

Free standing porous composite films and membranes obtained through substrate-guided assembly

Development of directed-self-assembly methods for composite nanomaterials is required for supporting the emergence and technological transfer of nanosciences. A new approach is proposed for inducing organized micron-sized pores in Ag+-doped PMMA composite films and membranes by topologically guided assembly on rough aluminum substrate’s grains during thermal annealing. The polymer-Ag+ porous thin film was obtained by spin coating of complex solution of poly(methyl methacrylate)/CF3COOAg on aluminium foil followed by thermal annealing at 85 °C. The film was reduced by UV irradiation to give a polymer-Ag film/membrane without distortion of the morphology.

Synthesis of CsPbX3 (X = Cl/Br, Br, and Br/I)@SiO2/PMMA composite films as color-conversion materials for achieving tunable multi-color and white light emission

All-inorganic cesium lead halide based perovskite nanocrystals (PNCs) exhibit promising optoelectronic properties, but their poor stability and anion exchange reaction limit their broad commercial applications. Herein, we demonstrated the successful synthesis of blue-green-red emitting CsPbX3 (X = Cl/Br, Br, and Br/I) PNCs via hot injection method, followed by silica-coating and embedding in poly(methylmethacrylate) (PMMA) matrix. The photoluminescence (PL) spectra of SiO2/PMMA-coated PNCs can be tuned continuously by regulating precursor composition ratio, from blue (CsPb(Cl0.5/Br0.5)3; 460 nm) to red (CsPb(Br0.4/I0.6)3 via green (CsPbBr3; 519 nm). The PNCs composite films exhibit improved stability (thermal-, moisture-, and photo-stability) because of the barrier formed by SiO2/PMMA coating and also displayed exceptional photoluminescent quantum yield (PLQY of blue, green, and red-emitting SiO2/PMMA coated PNCs are 37%, 86%, and 71%, respectively) with longer lifetimes inhibiting anion exchange. Eventually, the PNCs-encapsulated SiO2/PMMA composite films were integrated into the UV LED chip as down-converting materials to construct a prototype white-peLED unit. The designed white-peLED unit demonstrated bright white light generating CIE coordinates (0.349, 0.350), a luminous efficiency (LE) of 39.2% and a color rendering index (CRI) of 84.7. The wide color gamut of 121.47% of NTSC and 98.56% of Rec. 2020 is also achieved with the built w-LED system. Therefore, the results demonstrated that CsPbX3 (X = Cl/Br, Br, and Br/I) PNCs@SiO2/PMMA composite films can be employed as efficient UV to visible color conversion materials for white-LEDs and backlighting.

Gradient dielectric constant sandwich-structured BaTiO3/PMMA nanocomposites with strengthened energy density and ultralow-energy loss

High energy storage density with low-energy loss polymer films are essential for high-performance electric devices. To avoid the high-energy loss of utilizing nonlinear polymer materials, a sandwich nanostructure comprising a linear polymer poly(methyl methacrylate) (PMMA) matrix embedded with a high dielectric constant BaTiO3 (BT) interlayer and poly(vinylidene fluoride) (PVDF) binder was constructed using a solution casting strategy. This structural design takes advantage of each component in the composite. The good dispersion of BT particles in the binder, which was incorporated between PMMA, enabled a high dielectric constant and fewer defects. Additionally, the excellent film formation ability of the PVDF binder guarantees the uniform thickness and stable structure of the BT mid-layer, and good miscibility between PVDF and PMMA enhanced the interaction between each layer. Interestingly, since the dielectric constant of PVDF was between BT fillers and PMMA, a dielectric gradient distribution mitigated the local electric field concentration, as proven by the simulation results. Consequently, a low-loss linear PMMA composite film exhibited satisfying breakdown strength and excellent discharged energy density, which were 25% and 460% higher than those of pristine PMMA, respectively.

Perpendicular and In‐Plane Conductivity of Poly(methyl methacrylate) Composite Films Filled with Carbon‐Based Fillers Prepared from Solution Casting Process

AbstractIn this study, poly(methyl methacrylate) (PMMA)/carbon black (CB), PMMA/carbon fiber (CF), and PMMA/carbon nanotube (CNT) conductive composite films with different filler concentrations are prepared using the solution casting technique. Both perpendicular and in‐plane direction conductivity of all the binary composite films are investigated, percolation thresholds (ϕc) of both directions of PMMA/CB, PMMA/CF, and PMMA/CNT composite films are investigated and the experimental data are fitted using McLachlan’s equation. For all the three investigated films, the perpendicular ϕc,⊥ and in‐plane ϕc,∥ with different fillers show totally different behaviors. Pristine CB, CF, and CNT as well as PMMA/CB, PMMA/CF, and PMMA/CNT composite films are discussed. The gravity effect of the fillers is found to be most significant in the PMMA/CB system. A schematic diagram of PMMA composite films with CB, CF, and CNT as filler prepared from solution casting process is presented to explain the distribution gradient of the fillers in the perpendicular direction of the film after solution casting. A power law behavior is revealed for different filler types (CB, CF, CNT) correlating the exponent t for McLachlan’s equation and corresponding ϕc for in‐plane and perpendicular directions.

Electrical, mechanical, and optical changes in MWCNT-doped PMMA composite films

In this study, we report the preparation of poly (methyl methacrylate)/multi-walled carbon nanotube (MWCNT) composite thin films by simple and efficient solution mixing and ultrasonic method and the electrical, optical, and mechanical characterizations. Scattered light intensity ( I sc), tensile modulus ( E), and surface conductivity ( σ) of these composites have increased with the addition of MWCNT into the composite. The observed behavior in electrical, optical, and mechanical properties of the poly (methyl methacrylate)/MWCNT composites was interpreted by site and classical percolation theory. The optical mechanical and electrical percolation thresholds of poly (methyl methacrylate)/MWCNT composites were determined as φ op = 3 wt%, φ m = 0 wt%, and φσ = 5 wt%, respectively. The optical ( t op), mechanical ( t m), and electrical ( t σ) critical exponents were calculated as 2.23, 0.43, and 0.11, respectively. Both the tensile modulus and tensile strength of poly (methyl methacrylate)/MWCNT composites were increased with increasing MWCNT content until it reaches to 10 wt%. However, above φ = 10 wt%, the mechanical properties of the composites were decreased due to the aggregation of MWCNTs, while the toughness does not show a significant change until φ = 10 wt% MWCNT content, whereas it was decreased above this value.

Investigation of structural, optical, electrical and mechanical properties of di-methyl-tin-di-chloride PMMA composite films

Films ofthickness (∼100 μm) of pure poly(methylmethacrylate) (PMMA) andits composite film containing different concentrations (2%, 4% , 6% and 8%) of di-methyl-tin-di-chloride ((CH3)2-Sn-Cl2) were synthesized by solution cast method. Thesesynthesized films were characterized by FTIR, XRD, SEM, UV–VIS spectroscopy, DMA, Impedance analyzer and Hall measurement for their structural, optical and electrical properties. The incorporation of organo-tin compound in main chain of PMMA enhances the absorbance (A) of these composites in the wavelength range 300–1100 nm as the concentration of organo-tin compound is increased and suggests that this can be used to plausibly tune the optical band gap. The ac conductivity of these composite films tends to increase with increase in frequency and concentration of organo-tin compound in the frequency range 100 Hz – 10 MHz at room temperature.Hall measurements also support this as it shows the charge carriers concentration to increase with increase in concentration of organo-tin compound. The data obtained using dynamic mechanical analyzersuggests the films to be more flexible on insertion of di-methyl-tin-di-chloride.

Preparation of WS2–PMMA composite films for optical applications

Monolayer-enriched liquid phase exfoliated WS2 is embedded into a polymer matrix. The resultant thin films are homogeneous, mechanically robust and smooth. Optical monolayer properties (e.g. photoluminescence) of the WS2 are retained in the films.

Highly dispersive Ba 0.6 Sr 0.4 TiO 3 nanoparticles modified P(VDF‐HFP)/PMMA composite films with improved energy storage density and efficiency

Polymer composite films with high energy density as well as high efficiency are promising dielectric materials in pulsed power systems. In improving the energy discharged efficiency, poly vinylidene fluoride-hexafluoropropylene [P(VDF-HFP)] film blended with 20 vol.% poly(methylmethacrylate) (PMMA), which has a much slimmer ferroelectric hysteresis loop, is employed as the polymer matrix. Highly dispersive Ba0.6 Sr0.4 TiO3 (BST) nanoparticles with an average particle size of 12.1 nm are utilised to improve the polarisation of the blend film without sacrificing the dielectric strength. Uniform nanocomposite films with high flexibility and excellent energy-storage performance are obtained. Especially, due to the optimisation of both polymer matrix and fillers, the BST modified P(VDF-HFP)/PMMA blend films show improved breakdown strength and depressed energy loss, which leads to an enhanced energy density of 10.3 J/cm3 at 378 kV/mm.

Significantly enhanced dielectric and hydrophobic properties of SiO2@MgO/PMMA composite films

In this article, we provide a feasible method to prepare high-dielectric-constant hydrophobic composite films, which show potential application as the insulator layer in electrowetting devices.

Synthesis and characterization of wide-scale UV–vis CUT-OFF laser filter using methyl violet-6B/PMMA polymeric composite films

Abstract Poly(methyl methacrylate) (PMMA) doped with different weight percent of methyl violet-6B (MV-6B) as polymeric films were prepared by a casting method. Different concentrations of MV-6B can affect both the crystal structure and optical properties of PMMA. The broad hump diffraction peaks present in PMMA at 2θ = 15.27°, 30.60°, and 40.69° are ascribed to amorphous PMMA. During the incorporation of MV-6B dye onto PMMA, the intense peaks of PMMA at the 2θ value of 15.27° and 30.6° became less intense, and d -spacing was changed. The X-ray results confirmed the strong electrostatic interaction of the cationic MV-6B dye with the anionic PMMA polymer. Furthermore, the transmittance of PMMA/MV-6B composites is decreased with the increase of MV-6B dopants concentrations onto the PMMA matrix; this may be attributed to the electrostatic interaction between the PMMA chains and the molecules of methyl violet-6B. MV-6B-doped PMMA possesses three distinct band gaps corresponding to the pure PMMA, and other two band gaps are for the MV-6B /PMMA composite films. PMMA/MV films with 3.333 wt% of MV-6B) showed a large scale CUT-OFF laser filter inside in the range from 190 to 670 nm. Our designed filter is a unique polymeric composite film for optoelectronic and laser applications.