In this study, the polyethylene oxide (PEO)/SiO2 nanoparticles (NPs) nanocomposite films with various SiO2 NPs concentrations were prepared using an in situ formation of NPs in the polymer matrix for ...self‐cleaning antireflected surface applications. The effect of SiO2 NPs in PEO/SiO2 NPs nanocomposite films on the structural, morphological, chemical, thermal, optical, and electrical properties of PEO/SiO2 NPs nanocomposite films was performed. According to the x‐ray diffraction and the differential scanning calorimetry analysis, the crystallinity degree of the nanocomposite films decreases by increasing the SiO2 NPs concentrations. The bandgap energy of PEO/SiO2 NPs nanocomposite films decreases from 3.95 to 3.55 eV as the SiO2 NPs concentration increases up to 10 wt.%. The average electrical conductivity of the PEO/SiO2 NPs nanocomposite films increases from 5.1 × 10−7 to 2.0 × 10−6 S/cm as the SiO2 NPs concentration increases up to 10 wt.%. The refractive index decreases to 1.64 at 550 nm for the PEO/SiO2 NPs nanocomposite films with 10 wt.% of SiO2 NPs, and the water contact angle decreases to around 0° after thermal treatment, which confirms that the PEO/SiO2 NPs nanocomposite films can be used as self‐cleaning antireflected surfaces.
Morphological and particle dispersion of PEO/SiO2 nanocomposite films.
Achieving high-efficiency materials-coated electrocatalysts for water splitting is crucial to produce and store renewable energy. Herein, zinc oxide (ZnO) films with wide bandgap (3.12 eV), low ...absorption coefficient in the visible region, and high electrical conductivity (740 S cm
−1
) were presented after using two modification techniques: first, intensive thermal treatment by annealing the sample for 500 °C for 1 h, which decreases the bandgap energy from 3.94 to 3.33 eV and increases the electrical conductivity from 0.4 to 1.1 mS cm
−1
due to vanishing of the organic residuals, reducing H impurities, and increasing the crystal degree. Second, UV light-induced persistent doping by treating the sample using a UV light for 1000 s decreases the bandgap energy from 3.33 to 3.12 eV and increases the electrical conductivity from 1.1 to 740 S cm
−1
due to hole trapping by oxygen vacancies at the surface of ZnO film. Finally, the water-splitting activity of ZnO film increased from 68.95 to 88.85% after UV light-induced persistent doping.
The photoswitching behavior of the polyacrylic acid (PAA) doped by methyl orange (MO) brush film was investigated using spectral analysis of UV‐Vis absorbance, Fourier Transformation Infrared ...spectroscopy, 2D electrical conductivity mapping and Atomic Force Microscopy. The kinetics and time evolution of the photoisomerization of the PAA‐MO PEBs film from E‐state to Z‐state by UV‐light irradiation, and reverse thermal relaxation to E‐state was explored. The results confirm that the photoisomerization kinetics of the overall peak is the superposition of the photoisomerization kinetics of S2ππ* transition, low‐ and high‐frequency of the S1nπ* transition bands. The E–Z transformation led to transforming the azobenzene from flat with no dipole moment to 3.0 D dipole moment. Hence, the electrical conductivity escalated accordingly. The transformation of E‐state to Z‐state led to the collapse of the formed brushes because of the angular rotational momentum consequent to E–Z isomerization.
Photoisomerization process of azobenzene
Nanocomposite films of polyaniline protonated with camphor sulfonic acid (PANI-CSA) hosted in polyethylene oxide (PEO) and incorporated with gallium nitride nanoparticles (GaN-NPs) were synthesized ...and characterized. Nanocomposite films were coated on activated fused silica substrates by employing the spin coating technique. Films of PANI-CSA, PEO, PANI-CSA-PEO, and PANI-CSA-PEO incorporated with GaN-NPs with a weight percent ratio of 10%, 20.07%, 38.76%, 77.83%, 93.03%, 100.78%, and 155.04% with respect to PANI-CSA were characterized using UV–Vis spectroscopy, XRD, and SEM. Refractive index (
n
), extinction coefficient (
k
), absorption coefficient (α), and bandgap energies (
E
g
) were deduced. The refractive index value of PANI-CSA-PEO at 550 nm is found to be 1.72. It increases to 1.82 when GaN-NPs have been added to PANI-CSA-PEO solution by 10 wt.%. Then, it decreased to 1.63 when GaN-NPs concentration was increased to 20.07 wt.%. When GaN-NPs is increased further to higher concentrations, the material becomes GaN-rich PANI-CSA-PEO, and the refractive index takes values ranging between 1.56 and 1.66 at the higher concentration. The typical crystalline structure of PANI-CSA was vanishing gradually as GaN-NPs content was increasing at 155% wt.%, and the GaN crystalline nature was dominating the film crystallography. Results are anticipated to contribute to preparing smart multifunctional devices based on the PANI-CSA-PEO doped with GaN-NPs.
We report the synthesis of hybrid thin films based on polymethyl methacrylate) (PMMA) and polystyrene (PS) doped with 1%, 3%, 5%, and 7% of cerium dioxide nanoparticles (CeO2 NPs). The As-prepared ...thin films of (PMMA-PS) incorporated with CeO2 NPs are deposited on a glass substrate. The transmittance T% (λ) and reflectance R% (λ) of PMMA-PS/CeO2 NPs thin films are measured at room temperature in the spectral range (250–700) nm. High transmittance of 87% is observed in the low-energy regions. However, transmittance decreases sharply to a vanishing value in the high-energy region. In addition, as the CeO2 NPs concentration is increased, a red shift of the absorption edge is clearly observed suggesting a considerable decrease in the band gap energy of PMMA-PS/CeO2 NPs thin film. The optical constants (n and k) and related key optical and optoelectronic parameters of PMMA-PS/Ce NPs thin films are reported and interpreted. Furthermore, Tauc and Urbach models are employed to elucidate optical behavior and calculate the band gaps of the as-synthesized nanocomposite thin films. The optical band gap energy of PMMA-PS thin film is found to be 4.03 eV. Optical band gap engineering is found to be possible upon introducing CeO2 NPs into PMMA-PS polymeric thin films as demonstrated clearly by the continuous decrease of optical band gap upon increasing CeO2 content. Fourier-transform infrared spectroscopy (FTIR) analysis is conducted to identify the major vibrational modes of the nanocomposite. The peak at 541.42 cm−1 is assigned to Ce–O and indicates the incorporation of CeO2 NPs into the copolymers matrices. There were drastic changes to the width and intensity of the vibrational bands of PMMA-PS upon addition of CeO2 NPs. To examine the chemical and thermal stability, thermogravimetric (TGA) thermograms are measured. We found that (PMMA-PVA)/CeO2 NPs nanocomposite thin films are thermally stable below 110 °C. Therefore, they could be key candidate materials for a wide range of scaled multifunctional smart optical and optoelectronic devices.
In this work, semiorganic crystal films based on sodium bis(2-methyllactato)borate (NaMB) doped with iodine (I
2
) were deposited on glass substrates using the dip-coating technique. The chemical, ...crystalline, and morphological structures were investigated. NaMB semiorganic crystal film has a monoclinic crystal structure with a P21/n space group and a crystallinity degree of 89.8%. Introducing I
2
into NaMB films reduces the crystallinity of the semiorganic crystal films. Moreover, the optical and electrical properties were investigated, including the refractive index, extinction coefficient, band structure, optoelectronic parameters, and electrical conductivity. Adding I
2
to NaMB films led to a decrease in the bandgap energy due to the formation of polarons between the valance and conduction bands. Finally, NaMB/I
2
semiorganic crystal film conductivity increases as the I
2
concentration increases, creating deep localized states in NaMB, leading to gap-state density changes by shifting the Fermi level and increasing the electrical conductivity.
We investigate and report on the kinematics of photoisomerization processes of polymer composite thin films based on azo dye methyl red (MR) hosted in polymethylmethacrylate (PMMA) incorporated with ...Benzyl dimethyl ketal (BDK) as a photo-initiator. Understanding photoisomerization mechanisms is crucial for several optical applications such as Read/Write/Erase (WRE) optical data storage media, UV light Read/Write heads, and UV light sensors. The as-prepared polymer composite thin films are characterized using UV–Vis spectroscopy. Furthermore, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) are employed to investigate the optical, chemical, and morphological properties of trans- and cis-states of PMMA-BDK-MR polymer composite thin films. The presence of the azo dye MR in the composite is essential for the efficient performance of the cis ↔ trans cycles through illumination ↔ thermal relaxation for Write/Read/Erase optical data storage and UV-light sensors. Moreover, UV–Vis and FTIR results confirm the hysteresis cycle of trans- and cis-states and that PMMA-BDK-MR thin films may be regarded as potential candidates for successful Write/Read/Erase optical data storage and UV-light sensors. In addition, the morphology of the thin film surface is investigated by SEM technique. The SEM images indicate that uncured surfaces of PMMA-BDK-MR thin films are inhomogeneous compared with the corresponding surfaces after curing. The transformation from inhomogeneous surfaces to homogeneous surfaces is attributed to the polymerization of thin films by UV curing.
We fabricated ferroelectric films of the organic molecular diisopropylammonium chloride (DIPAC) using the dip-coating technique and characterized their properties using various methods. ...Fourier-transform infrared, scanning electron microscopy, and X-ray diffraction analysis revealed the structural features of the films. We also performed ab-initio calculations to investigate the electronic and polar properties of the DIPAC crystal, which were found to be consistent with the experimental results. In particular, the optical band gap of the DIPAC crystal was estimated to be around 4.5 eV from the band structure total density-of-states obtained by HSE06 hybrid functional methods, in good agreement with the value derived from the Tauc plot analysis (4.05 ± 0.16 eV). The films displayed an island-like morphology on the surface and showed increasing electrical conductivity with temperature, with a calculated thermal activation energy of 2.24 ± 0.03 eV. Our findings suggest that DIPAC films could be a promising alternative to lead-based perovskites for various applications such as piezoelectric devices, optoelectronics, sensors, data storage, and microelectromechanical systems.
Silicone oils have the role in maintaining the attachment of the retina in conditions where the risk of retinal re-detachment is high. However, silicone oils have the tendency to emulsify with ...subsequent complications. In this work, analyses have been performed to understand changes that occurred to the optical, and physical characteristics of the oil after removal from the vitreous cavity of patients underwent pars plana vitrectomy (PPV) for fibrovascular membranes/tractional retinal detachment (FVM/TRD).
Four samples of silicone oil were allocated from patients who underwent PPV for FVM/TRD. The Fourier-transform infrared (FTIR) spectroscopy, micro-viscometry, and ultraviolet-visible spectrometer analyses were utilized to determine the changes in its chemical bondings, viscosity, absorbance, transmittance, buoyance, and specific gravity.
The mean age of the patients was 49.0 years. The mean duration of silicone oil implantation was 18.9 months. FTIR analysis showed significant breaking in the chemical bonding that was related to the lens status during the primary PPV, the presence of significant retinal hemorrhages, the duration of silicone oil implantation, and the degree of silicone oil filling. Similarly, viscosity and contact angle analyses revealed a reduction in the viscosity with similar factors to the FTIR analysis. Moreover, absorbance and transmittance were largely affected by the aggressiveness of FVM/TRD.
This study revealed that certain factors such as the age of the patient, duration of silicone oil implantation, lens status, and the presence of retinal hemorrhages, the degree of silicone oil filling and aggressiveness of FVM/TRD may contribute to the emulsification process.
Metal oxide nanoparticles (MONPs) (ZnO, TiO
2
, SiO
2
, and CuO NPs) were synthesized with an average size of around 50 nm. The synthesized MONPs were incorporated into Poly(methyl methacrylate) ...(PMMA) matrix deposited on glass substrate led to form PMMA/MONPs nanocomposite films. Fourier-Transform Infrared (FTIR) spectroscopy was employed to investigate the vibrational bands of pure PMMA and the incorporated PMMA/MONPs nanocomposite films. SEM micrographs showed the amorphous morphology of PMMA/MONPs nanocomposite films indicating the excellent dispersion of the MONPs on the surface. PMMA and PMMA/MONPs were exposed to the UV light for a period of 1, 3, and 5 min to investigate the impact on their refractive index (
n
). The UV-light exposure led to cause an increase in the refractive index of the PMMA in the visible region and decrease in the UV region and the opposite way around in the PMMA/MONPs nanocomposite films. Applying Maxwell–Garnett and Bruggeman's effective medium approximation models to investigate the distribution of the MONPs in the PMMA matrix shows a transfer from continuous aggregated nanoparticles to spherical or ellipsoidal distribution.
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