High Light Transmittance Research Articles

Fabrication of hydrolyzed keratin-modified rigid polyurethane foams and its thermal stability and combustion performance

Rigid polyurethane foams (RPUFs) were synthesized with hydrolyzed keratin using the “one-step method” of all-water foaming. Thermogravimetric analysis, pyrolysis kinetics analysis, cone calorimetry and smoke density (Ds) were used to investigate the effects of hydrolyzed keratin on thermal stability and combustion performance of RPUFs. The results showed that the modified RPUFs with 12.5 wt% hydrolyzed keratin (RPUF-HK5) had the lowest mass loss, the highest integrated program pyrolysis temperature, the highest activation energy, the lowest Ds (25.32 and 22.57), the highest light transmittance (64.30% and 67.46%), and total heat release (1.85 MJ/m2, 2.18 MJ/m2 and 2.92 MJ/m2), which indicated that RPUF-HK5 had better thermal stability and combustion performance. The current research results provided a useful reference for the preparation of the RPUFs with good thermal stability by bio-based modification.

Magnesium fluoride microcavity-based non-fullerene semitransparent organic solar cells with high peak transmittance and low efficiency loss rate

Microcavity-based semitransparent organic solar cells (ST-OSCs) have become a hot issue in the research field of green energy harvesting due to their wider potential applications in colored photovoltaic glass, building-integrated photovoltaics, and so on. However, for this kind of ST-OSCs, high photoelectric conversion efficiency (PCE) and high peak transmittance cannot usually be achieved simultaneously. To circumvent the problem, this paper proposes MgF2 microcavity with a structure of Au/Ag/MgF2/Ag for ST-OSCs so that high peak transmittance can be achieved at low cost of PCE. The device structure of ST-OSCs is Glass/ITO/ZnO/PTB7-Th: IEICO-4F/MoO3/Au/Ag/MgF2/Ag. By combining the high transmittance of MgF2 microcavities with the low absorption of IEICO-4F in the blue light, a colorful ST-OSCs with high blue light transmittance can be obtained. The IEICO-4F in the active layer shows strong optical absorption in the near-infrared wavelength region, but weak absorption in the visible region. The results demonstrate that the peak transmittance of ST-OSCs reached a high value of 48% at 440 nm and the PCE reached 10.4%. Such a high peak transmittance is achieved while the PCE reduction compared to the control opaque device is about 5%. The PCE loss rate at each peak transmittance is the lowest among the reported values for the similar ST-OSCs devices. By adjusting the thickness of MgF2, ST-OSCs with different colors can be obtained, the peak transmittance of which is over 32% and the PCE loss rate is less than 7.25%. This report provides a new approach to solve the trade-off between efficiency and transmittance of ST-OSCs.

Photothermal insulation mechanism of submicron ITO hollow particles in PVDF film

In this study, submicron Sn[Formula: see text]-doped In2O3 hollow particles (indium-tin oxide (ITO)) with a lyrium shell-like surface were synthesized via solvothermal method. The appropriate addition of these particles into polyvinylidene fluoride (PVDF) films exhibits high visible light transmission and effective UV/IR blocking properties, surpassing those of ITO nanoparticles. This can be attributed to the reduced absorption of UV/IR radiation by the hollow ITO particles, as well as their higher diffuse reflectivity and thermal insulation.

Development method of splitting the radio-reflective large-sized reflector surface into cutting patterns made of mesh with coarse cells

An important design component of space antenna reflectors is a reflecting surface. At present, metallic knitted mesh fabric is most often used as a reflective surface; it fully meets the requirements for such surfaces in terms of physical and mechanical properties. Particularly important characteristics for large-sized reflectors are low specific gravity and high light transmission coefficient, which a mesh with coarse cells provides. However, the structural features of this mesh fabric impose additional requirements on its use as a reflective surface for large-sized transformable reflectors. The article deals with a special approach to designing patterns for a reflective surface made of mesh with coarse cells. The developed pattern cutting option allows to obtain a reflective surface with the least distortion (error), in accordance formulated criteria. The authors have suggested the option of obtaining cutting patterns of metallic mesh fabric, described the advantages of the proposed option over the classical one. The cutting pattern of the parabolic surface for the offset reflector was obtained. The proposed cutting pattern option was analyzed. Furthermore, optimization was carried out, which made it possible to maintain the integrity of the cellular structure of patterns along one loop row. The compared results show that the developed cutting pattern option completely complies with the requirements and it can be used to form a reflective surface from the metallic knitted mesh with coarse cells.

Preparation of high-strength and degradable films from waste soft tissue by thermal “welding” using ionic liquid

This paper presents a simplified one-step method for preparing high-strength and degradable films, significantly enhancing the reuse value of waste cellulose fibers. By precisely controlling water evaporation, we successfully achieved partial dissolution of viscose fiber in ionic liquid ([BMIM]Cl). This enabled the bonding of fiber surfaces, resulting in the formation of all-cellulose composite films through a straightforward thermal “welding” process. The film properties can be further improved by modifying the coagulation bath composition. We conducted a comprehensive study on the morphology, mechanical properties, and thermal properties of all-cellulose composite films regenerated from different coagulation baths. XRD analysis revealed the coexistence of cellulose crystal phases I and II in the films. These composite films exhibited excellent mechanical properties, with a tensile strength of 25 MPa and a breaking elongation of 32% for the film regenerated in PEG coagulation bath. Moreover, the films demonstrated good thermal stability, resistance to chemical reagents, and a high light transmission rate of 80%. In a soil landfill degradation experiment spanning 90 days, the films exhibited a degradation rate of 93.4%. These films hold significant potential for applications in the field of specialized packaging materials. Overall, our work provides a promising and environmentally friendly approach for the recycling of waste cellulosic materials.

Highly Efficient (>13%) and Robust Flexible Perovskite Solar Cells Using an Ultrasimple All-Carbon-Electrode Configuration.

Fragile and expensive transparent conductive oxide anodes and noble metal cathodes in typical perovskite photovoltaic devices pose unavoidable issues, i.e., poor flexibility and high material cost, making it inaccessible to commercial application. Here, we report an ultrasimple indium tin oxide (ITO)-free and HTL-free all-carbon-electrode flexible perovskite solar cell (AC-F-PSC) with an architecture of PEN/carbon/SnO2/perovskite/carbon which contains an anode made of a carbon-based integrator (CNT-GR) comprising carbon nanotubes and low-dose graphene, and a cathode made of the commonly used conductive carbon. The CNT-GR anode exhibits low sheet resistance, high light transmittance, and superior flexibility beyond ITO. Density functional theory calculations reveal that O atoms from GR anchored onto the interwoven CNT network have strong covalent binding capacity with bond-deficient Sn ions, inhibiting the formation of oxygen vacancies in SnO2. Such a binding effect induces a significant reduction of the conduction band minimum of SnO2, yielding favorable energy level alignment for carrier transport at the SnO2/perovskite interface. Also, a heat-pressing approach as a tiny trick is used to fill the gaps at the perovskite/carbon cathode interface. The resulting AC-F-PSC device attains an efficiency of 13.14%, which is a record value among reported carbon-electrode F-PSCs, with superior mechanical flexibility, i.e., ∼71% of initial efficiency after bending 4000 cycles at 4 mm bending radius. This PSC based on an ultrasimple all-carbon-electrode offers a promising route for robust and cost-effective flexible photovoltaic devices.

Effect of swelling degree on structural evolution and orientation behavior of Poly(vinyl alcohol) films during stretching

For the preparation of polarizing film, the initial condensed structure of the PVA film is the key factor to determine the subsequent process conditions such as dyeing and stretching of PVA film. In the present work, the difference of the initial condensed structure of Poly (vinyl alcohol) (PVA) films with different swelling degrees and their influence on the orientation behavior and morphological structure evolution during stretching were investigated in detail. The results showed that the PVA film with a higher swelling degree possessed a lower content of microfibril structure at the same strain and the higher critical strain εs, revealing that the undissolved lamellae could act as the precursor for the formation of oriented microfibrillar structures. Furthermore, in order to investigate the influence of different swelling degrees on the lamellar orientation and the formation of microfiber structure during the stretching of PVA films, the long period of lamellae (Lp), the period of nanofibrils (Lf), and the Full Width at Half Maxima (FWHM) of Lf were calculated. It was found that the Lp and the Lf of the microfibrillar structure in the equatorial and meridional directions were larger and the FWHM of Lf was smaller for PVA films with higher swelling degree, indicating that the PVA film with a higher swelling degree could form a more relaxed and uniform periodically folded microfibrillar network, resulting in a higher light transmission in the visible region. Therefore, on the premise of ensuring the mechanical strength, the PVA film with a relatively higher swelling degree can be used to obtain commercial polarizing films with excellent light transmittance.

A hydrogel system for drug loading toward the synergistic application of reductive/heat-sensitive drugs

The preparation of hydrogels as drug carriers via radical-mediated polymerization has significant prospects, but the strong oxidizing ability of radicals and the high temperatures generated by the vigorous reactions limits the loading for reducing/heat-sensitive drugs. Herein, an applicable hydrogel synthesized by radical-mediated polymerization is reported for the loading and synergistic application of specific drugs. First, the desired sol is obtained by polymerizing functional monomers using a radical initiator, and then tannic-acid-assisted specific drug mediates sol-branched phenylboric acid group to form the required functional hydrogel (New-gel). Compared with the conventional single-step radical-mediated drug-loading hydrogel, the New-gel not only has better chemical/physical properties but also efficiently loads and releases drugs and maintains drug activity. Particularly, the New-gel has excellent loading capacity for oxygen, and exhibits significant practical therapeutic effects for diabetic wound repair. Furthermore, owing to its high light transmittance, the New-gel synergistically promotes the antibacterial effect of photosensitive drugs. This gelation strategy for loading drugs has further promising biomedical applications.

Fabrication of soybean oil-based polyol modified polyurethane foam from ammonium polyphosphate and its thermal stability and flame retardant properties

Abstract Rigid polyurethane foams (RPUFs) were prepared using biomass soybean oil-based polyol and ammonium polyphosphate (APP) as raw materials. The effects of APP on the thermal stability and combustion performance of soybean oil-based polyol-modified RPUFs were investigated by thermogravimetric analysis, pyrolysis kinetic analysis, limiting oxygen index (LOI) test, cone calorimetry (CONE), scanning electron microscopy (SEM), and smoke density (Ds). The results showed that the modified RPUF with 20 wt% APP (RPUF-S3-20) had the lowest mass loss, the highest integrated programmed decomposition temperature and the highest activation energy. In addition, RPUF-S3-20 had the lowest Ds (30.9), the highest light transmittance (61.4 %), the lowest heat release rate (602.7 kW/m2, 506.8 MJ/m2, and 847.3 kW/m2) and the total heat release (18.3 MJ/m2, 21.4 MJ/m2, and 31.4 MJ/m2), which showed that RPUF-S3-20 had good thermal stability and flame retardant performance. The current results can provide an effective reference for the preparation of environmentally friendly RPUF by bio-based modification.

Electrochemical reduced ITO for high-stability asymmetric supercapacitors

Indium tin oxide coated glass (ITO) is considered as an ideal conductive substrate for the optoelectronic devices due to its high conductivity, light transmittance and chemical and thermal stability. However, its application in supercapacitors is quite limited because of the poor interfacial adhesion between ITO and electrochemically active materials. In this study, by electrochemically reducing ITO film, we have significantly enhanced the adhesion between current collectors (R-ITO) and the electrochemically active materials (MnO2 and PEDOT) by forming In/Sn nano-particles at the R-ITO surface. The fabricated electrodes based on each material have delivered a specific capacitance over 30 mF cm −2 as well as an excellent cycling stability. Further, the obtained solid-state asymmetric supercapacitor based on R-ITO@MnO2 and R-ITO@PEDOT electrodes gives a high operating voltage of 1.5 V, an energy density of 4.6 μWh cm−2 and a prominent stability (capacitance retention of 93.2% after 2500 cycles).

Phenomenon of courtyards being roofed and its significance for building energy efficiency

Courtyard building is an important type of vernacular architecture, widely distributed in different climate zones around the world. Traditionally, courtyards are characterized by opening to the sky, providing buffer spaces for ventilation and light for the surrounding buildings. However, in Hebei, China, local buildings are showing an evolution trend characterized by the courtyards being roofed (CBR). This spontaneous evolution presents the diversity of CBR technologies (CBRTs), including light-transmitting CBRTs (T-CBRTs) and non-light-transmitting CBRTs (NT-CBRTs). Based on field measurements and simulation technology, the improvement effect of CBR on building energy efficiency (EE) is analyzed, and the EE of different CBRTs is compared. The results show that, T-CBRT and NT-CBRT can reduce the annual total energy consumption of open courtyards by 19.97% and 15.41% respectively without upgrading the original envelope structure. The analysis of the impact mechanism shows that CBRT increases the temperature of the courtyard and the room by improving the solar energy collection efficiency and expanding the heat storage space, which effectively reduces the heat leakage caused by the envelope and ventilation, and shortens the heating time. The light transmittance of the roof material is the most critical parameter affecting the EE of T-CBRT, and the roof height largely determines the performance of NT-CBRT. Multi-layer glass or concrete panels are not the best choice for CBRT roofing materials, and plastic films or polycarbonate sheets with high light transmittance and anti-aging are recommended. CBR is considered as a promising development direction because it can reduce the economic burden of energy consumption for local farmers by improving the EE of buildings.

Farklı Türden Kontak Lenslerin Ultraviyole Işık Geçirgenliğinin Ölçülmesi

Scientific evidence showing the harmful effects of ultraviolet radiation on different ocular tissues has led manufacturers to incorporate UV-blocking monomers into contact lenses. In this study, the spectral and optical properties of contact lenses were analyzed in the ultraviolet and visible light wavelength ranges using the Jasco V-730 UV/VIS spectrophotometer device. The results obtained showed that in the lens samples examined, the light transmittance in the wavelength (550nm) range to which the human eye is most sensitive is over 70% and the maximum value is 72.98% in B contact lenses. The largest cutting edge wavelength value was obtained in the A contact lens as 376 nm. At 550 nm, the absorption spectra were found to be below 0.12. In terms of visual quality, visible light transmittance is expected to be high and ultraviolet light transmittance is expected to be minimal. The degree of damage caused by the amount of ultraviolet light absorption increases. Among the contact lenses with and without ultraviolet-protected monomers, lens A did not transmit the UV-B wavelength region, while lens B transmitted UV-A and UV-B wavelengths. This result showed that the protection of lens A was higher. It is seen that the UV transmittance taken with the phocometer is 45% UV in A lens and 91% UV in B lens. The results obtained by UV/VIS spectrophotometer and phocometer supported each other. The results will contribute to the literature by revealing the importance of UV-protected monomer-containing contact lenses in vision equipment, and by enabling the development and selection of full-protection contact lenses.

Transparent 0D Antimony Halides Glassy Wafer with Near‐Unity Photoluminescence Quantum Yield for High Spatial Resolution X‐Ray Imaging

AbstractLarge‐sized transparent scintillators with a high photoluminescent quantum yield (PLQY) and self‐absorption‐free properties are highly desired to achieve high spatial resolution X‐ray imaging. In this research, a transparent 0D organic–inorganic (ETP)2SbCl5 (ETP = Ethyl triphenylphosphine) amorphous wafer is developed by melting the ETPCl and SbCl3 mixture and then undergoing a quenching process. The obtained amorphous wafer exhibits a high light transmittance of 86% in the range of 450–800 nm. It also shows a light emission peak at 624 nm, a Stokes shift of 259 nm, and PLQY approaching unity (99.3%). These properties enable it to produce X‐ray images with a high spatial resolution of 19.0 lp mm−1 at a modulation transfer function (MTF) value of 0.2, among the best values reported. Additionally, it also shows remarkable stability under continuous X‐ray illumination. Its unique optical properties and ability to be processed in large sizes make the organic–inorganic metal halide transparent wafer a promising scintillator. This also demonstrates the potential application of the melt‐quenching method in fabricating highly luminescent, low‐electronic‐dimensional metal halide wafers.

Experimental investigation and modeling of the mechanical properties of construction PMMA at different temperatures

Poly-methyl-methacrylate (PMMA) is a polymer material with increasing applications in buildings as an alternative to glass. Compared with glass, PMMA is lightweight, has high light transmittance, and has no risk of self-explosion. PMMA can be bonded to form large components without visible connections through bulk polymerization. PMMA used in construction (construction PMMA) is not toughened by the directional stretching process, which makes it different from the directional PMMA used in aerospace. This study aimed to explore the mechanical properties of construction PMMA. First, uniaxial tensile tests of the base coupons (without bonding areas) and bonding coupons (with bonding areas) at different temperatures (-40 to 60 °C) were conducted, and uniaxial compressive tests were conducted at the same temperatures. Thereafter, predictive formulae were proposed to describe the effect of temperature on the mechanical properties of construction PMMA under tension and compression, and a reduction factor for the ultimate strength of the bonding coupon was proposed. Subsequently, an exponential stress–strain relationship was proposed to describe the mechanical behavior of construction PMMA at different temperatures, which exhibited better accuracy. Finally, the capacity tests of the two PMMA beams were conducted. Finite element models of the test beams were established using the proposed stress–strain relationship. The accuracy of the proposed stress–strain relationship was verified by comparing the results of the finite element analyses and the test.

Microheater-Integrated Microlens Array for Robust Rapid Fog Removal.

In extreme environments, fog formation on a microlens array (MLA) surface results in a device failure. One reliable solution for fog removal is to heat the surface using a microheater. However, due to the surface interference, the combination of these two microdevices remains elusive. In this study, we introduce lift-off and electroless plating into femtosecond laser processing to fabricate a microheater integrated MLA (μH-MLA) on the same substrate with high light transmittance, durability, and fog removal efficiency. Laser-induced micro-nano grooves enable the microheater to be tightly coupled with the MLA and have high heating performance, thus maintaining a stable performance for over 24 h during continuous operation as well as under long time ultrasonic vibration and mechanical friction. With a rapid response time (τ0.5) of 17 s and a high working temperature of 188 °C, the μH-MLA removed fog that covers the entire face within 14 s. Finally, we prove the use of this fabrication method in large areas and curved surface environments. This study provides a flexible, stable, and economical method to integrate micro-optical and microelectrical devices.

A high‐strength flexible transparent reprocessable polyurea film based on dual dynamic noncovalent interactions

AbstractTo address the issues that waste of resources and environmental pollution caused by discarded materials, dynamic bonds are widely introduced into polymers to endow them with reprocess ability. However, there are some obvious issues in existing research such as poor toughness, low fracture elongation, and inability for repeated reprocessing of materials. Considering above problems, this study introduces dense hydrogen bonding and cation–π interactions into the polyurea system, and develops a high‐performance transparent film based on dual dynamic non‐covalent interactions, which enables the film to be reprocessed. Through the synergy of the dual non‐covalent networks, the film exhibits a high tensile strength of 79.6 ± 3.9 MPa and good hardness (pencil hardness of 4H, elastic modulus of 2.69 GPa). It can effectively resist the scratching of copper brush and maintain more than 97% of its initial mechanical strength after being reprocessed five times. In addition, the film has good adhesion to various substrates, as well as high flexibility (0.5 mm) and excellent optical properties (high light transmission of 91.1% and low haze of 0.94%). This study proposes a novel approach to enable polymer materials to be reprocessed and demonstrates the preparation of a film with great potential in optical protection and wearable devices.

Photosensitizing deep-seated cancer cells with photoprotein-conjugated upconversion nanoparticles

To resolve the problem of target specificity and light transmission to deep-seated tissues in photodynamic therapy (PDT), we report a cancer cell-targeted photosensitizer using photoprotein-conjugated upconversion nanoparticles (UCNPs) with high target specificity and efficient light transmission to deep tissues. Core-shell UCNPs with low internal energy back transfer were conjugated with recombinant proteins that consists of a photosensitizer (KillerRed; KR) and a cancer cell-targeted lead peptide (LP). Under near infrared (NIR)-irradiating condition, the UCNP-KR-LP generated superoxide anion radicals as reactive oxygen species via NIR-to-green light conversion and exhibited excellent specificity to target cancer cells through receptor-mediated cell adhesion. Consequently, this photosensitizing process facilitated rapid cell death in cancer cell lines (MCF-7, MDA-MB-231, and U-87MG) overexpressing integrin beta 1 (ITGB1) receptors but not in a cell line (SK-BR-3) with reduced ITGB1 expression and a non-invasive normal breast cell line (MCF-10A). In contrast to green light irradiation, NIR light irradiation exhibited significant PDT efficacy in cancer cells located beneath porcine skin tissues up to a depth of 10 mm, as well as in vivo tumor xenograft mouse models. This finding suggests that the designed nanocomposite is useful for sensing and targeting various deep-seated tumors.

One-step assembly of organic-inorganic hybrid coatings with superior thermal insulation, sustainable antifogging and self-cleaning capabilities

Multifunctional transparent glass integrating energy-saving and antifogging properties has receiving continuous attention in basic research and practical applications, which is still plagued by the lack of simple and general methods for low-cost and large-area fabrication. Herein, a multifunctional window with high thermal insulation, antifogging, and self-cleaning functions is rationally fabricated via coating a mixture of polyacrylic acid (PAA), polypropylene glycol (PPG), 3-glycidyloxypropyltrimethoxysilane (KH-560), and cesium tungsten bronze (CWO) nanoparticles on a monolayer film. The synergistic effect between the plentiful hydroxyl/carboxyl groups of PAA/PPG and the nano-textured surface induced by CWO nanoparticles enabled the monolayer film to exhibit superhydrophilic, self-cleaning and antifogging capabilities. The film maintains its antifogging properties even after 80 rubbings of dust-free cloth and 120 days of exposure tests at room temperature. Moreover, the as-prepared window can reduce the indoor temperature by 15.8 °C compared to a normal window at noon. The energy simulation results demonstrate that such windows can reduce energy consumption by 18.9 % in local cities compared to traditional windows. The high visible light transmittance, low haze, stable and durable antifogging ability, distinguished energy-saving effect and climate adaptability, as well as the solution-based process of this multifunctional window make it promising for architectural and automotive glass applications.

Transparent single crystal graphene flexible strain sensor with high sensitivity for wearable human motion monitoring

Human-machine interfaces, smart glasses, touch screens and some electronic skins all require highly transparent and flexible strain sensing components. Flexible strain sensors usually use microstructures or porous active materials to improve sensitivity and response speed, resulting in low transparency of the device. Graphene has attracted extensive attention due to its special physical properties, especially excellent flexibility, and high transmittance. However, previous studies found that it is difficult to obtain high gauge factor in graphene. Thus, graphene cannot be used to monitor subtle deformations. Although previous research has shown that the strain sensors based on the combination of graphene and other materials have high sensitivity, but lack of transmittance. In this paper, we report a single-crystal graphene (SCG) strain sensor fabricated by encapsulating single-crystal hexagonal graphene in a flexible substrate. The strain sensor shows excellent performance with a high gauge factor (16.9) because it is not affected by wrinkles, grain boundaries and additional layers. Further, the strain sensor retains the advantage of high light transmittance of graphene. This sensitive SCG strain sensor has been demonstrated to detect a range of human motions, including finger gestures, tiny vibration of different sounds and heartbeats with high performance. This work further confirms the application of graphene in strain sensors, and provides new ideas for the research of graphene-based transparent strain sensors.

Dopamine‐Based High‐Transparent Hydrogel as Bioadhesive for Sutureless Ocular Tissue Repair

AbstractOcular injuries and their complications represent the most common causes of visual impairment. For ocular surgery, there is an unmet need for highly transparent bioadhesives with superior adhesion, biocompatibility, and regenerative properties. Herein, a novel high‐transparent bioadhesive hydrogel composed of gelatin methacryloyl (GelMA) and dopamine methacrylamide (DMA) is developed by in situ oxidative free‐radical polymerization. This bioadhesive hydrogel overcomes the fundamental weakness of mussel‐inspired adhesive copolymers in clinical practice by combining multiple favorable properties, including high light transmission, mechanical strength, adhesive strength, and biocompatibility. DMA significantly enhances corneal epithelial cells adhesion, proliferation, and migration on GelMA, and prevents the accumulation of reactive oxygen species (ROS) in corneal epithelial cells. In rabbit models of corneal and conjunctiva transplantation, the bioadhesive is able to decrease the inflammatory response and fibrosis formation induced by suture surgical trauma. In addition, the rabbit corneal stromal defect model reveals that the Gel/DMA bioadhesive could effectively seal corneal defects, accelerates corneal re‐epithelialization, and promotes wound healing. Thus, given the advantages of high bioactivity and simple preparation, the Gel/DMA bioadhesive represents a promising strategy for suture‐free ocular repair.