PET Substrate Research Articles

On the Role of Temperature in the Depolymerization of PET by FAST-PETase: an Atomistic Point of View on Possible Active-Site Pre-Organization and Substrate-Destabilization Effect.

Enzyme FAST-PETase, recently obtained by machine learning approach, can depolymerize polyethylene terephthalate (PET), a synthetic resin employed in plastics and in clothing fibers. Therefore it represents a promising solution for the recycling of PET-based materials. In the present study, a model of PET was adopted to describe the substrate, and all-atoms classical molecular dynamics (MD) simulations on apo- and substrate bound- FAST-PETase were carried out at 30°C and 50°C, to provide atomistic details on the binding step of the catalytic cycle. Comparative analysis sheds light on the interactions occurring between the FAST-PETase and 4PET at 50 °C, the optimal working condition of the enzyme. Pre-organization of the enzyme active and binding sites has been highlighted while MD of FAST-PETase:4PET pointed out on the occurrence of solvent-inaccessible conformations of the substrate promoted by the enzyme. Indeed, neither of these conformations were observed during MD of substrate alone in solution performed at 30 °C, 50 °C and 150 °C. The analysis led us to propose that, at 50 °C, the FAST-PETase is pre-organized to bind the PET and that the interactions occurring in the binding site can promote more reactive conformation of PET substrate, thus enhancing the catalytic activity of the enzyme.

Developing a Simple, Effective, and Quick Process to Make Silver Nanowires with a High Aspect Ratio.

A growing number of people are interested in using silver nanowires (AgNWs) as potential transparent and conductive materials. The production of high-performance and high-throughput AgNWs was successfully optimized in this work using a one-step, straightforward, and reproducible modified polyol approach. The factors influencing the morphology of the silver nanowires have undergone extensive research in order to determine the best-optimized approach for producing AgNWs. The best AgNW morphology, with a length of more than 50 m and a diameter of less than 35 nm (aspect ratio is higher than 1700), was discovered to be produced by a mixture of 44 mM AgNO3, 134 mM polyvinylpyrrolidone (PVP) (Mo.Wt 40,000), and 2.4 mM KCl at 160 °C with a stirring rate of 100 rpm. With our improved approach, the overall reaction time was cut from almost an hour with the conventional polyol method to a few minutes. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and ultraviolet (UV) spectroscopy were used to characterize AgNWs. The resultant AgNWs' dispersion was cleaned using a centrifuge multiple times before being deposited on glass and PET substrates at room temperature. In comparison to commercial, delicate, and pricey indium-doped tin oxide (ITO) substrates, the coated samples displayed exceptionally good sheet resistance of 17.05/sq and optical haze lower than 2.5%. Conclusions: Using a simple one-step modified polyol approach, we were able to produce reproducible thin sheets of AgNWs that made excellent, flexible transparent electrodes.

Photocatalytic reduction of CO2 over Ni-CuxO thin films towards formic acid production

Copper oxide (CuO) is an abundant and low-cost material, which is active as a photocatalyst under visible light due to its narrow band gap (1.3 eV). In the present work, CuO thin films at different Ni doping amounts (5, 10, and 30 % mol) were prepared using two different techniques: dip-coating and electrodeposition of Cu precursors over glass and PET substrates. X-Ray analysis results indicate the presence of Cu2O, CuO and Cuo phases in PET substrate films, while only CuO phase in Glass-substrate films. Glass substrate films presented a higher formic acid production performance reaching 50,000 μmol/g·h using 5% Ni doping on CuO. This higher activity was associated with a lower ratio between the adsorbed oxygen and the oxygen located in the crystal lattice, attributing this to the oxygen species adsorbed over the surface that could hinder the active sites of the material. Finally, PET substrate samples present a higher ratio between adsorbed oxygen and lattice oxygen, however, the Cu2O phase presents less affinity to adsorb CO2 molecules than CuO monoclinic phase reducing the photoactivity of the CO2 photoreduction. Majority charge carrier mobility of 4 cm2/Vs and 35 cm2/Vs for Cu2O and CuO respectively, with the charge carrier concentration of ∼1 × 1019 order was achieved switching the conducting type.

A Flexible and Transparent PtNP/SWCNT/PET Electrochemical Sensor for Nonenzymatic Detection of Hydrogen Peroxide Released from Living Cells with Real-Time Monitoring Capability.

We developed a transparent and flexible electrochemical sensor using a platform based on a network of single-walled carbon nanotubes (SWCNTs) for the non-enzymatic detection of hydrogen peroxide (H2O2) released from living cells. We decorated the SWCNT network on a poly(ethylene terephthalate) (PET) substrate with platinum nanoparticles (PtNPs) using a potentiodynamic method. The PtNP/SWCNT/PET sensor synergized the advantages of a flexible PET substrate, a conducting SWCNT network, and a catalytic PtNP and demonstrated good biocompatibility and flexibility, enabling cell adhesion. The PtNP/SWCNT/PET-based sensor demonstrated enhanced electrocatalytic activity towards H2O2, as well as excellent selectivity, stability, and reproducibility. The sensor exhibited a wide dynamic range of 500 nM to 1 M, with a low detection limit of 228 nM. Furthermore, the PtNP/SWCNT/PET sensor remained operationally stable, even after bending at various angles (15°, 30°, 60°, and 90°), with no noticeable loss of current signal. These outstanding characteristics enabled the PtNP/SWCNT/PET sensor to be practically applied for the direct culture of HeLa cells and the real-time monitoring of H2O2 release by the HeLa cells under drug stimulation.

Sputter-deposited highly flexible noble metal multi-layer electrode viable for energy and luminescent devices

Transparent conducting Indium tin oxide (ITO) electrode is predominantly utilized currently in most of the display and energy harvesting devices. However, its sustained usage is an imminent imperil due to its low availability, dwindling supply and recycling issues. There is a dire need to supplement the usage of ITO with appropriate alternatives in desired resistance scale, depending on the device necessity. At this juncture, an analogous viable transparent conducting ultrathin Au/Cu/Ag/Pt/Au noble metallic multi-layer electrode sputtered onto PET substrate is investigated. The multi-layer presents highest transmittance of 44% (at 500 nm) with a nearly uniform trend over the complete visible region of the electromagnetic spectrum. Electrical transport measurements of the multi-layer yielded 60 Ω/□ sheet resistance and a carrier mobility of 2.02 cm2 V−1 s−1. The transition of bare PET from hydrophilic (73.85°) to hydrophobic (99.83°) upon depositing the metallic multi-layer is indicated from contact angle measurements. The surface features studied using atomic force microscope and optical profiler show a uniform topography, free from cracks. The metallic multi-layer exhibits high mechanical strength up to 50,000 bending - twisting sequences. The measured surface work function of Au/Cu/Ag/Pt/Au metallic multi-layer is 5.01 eV. The ultrathin pliable metallic multi-layer tested in a piezoelectric nanogenerator device and alternating current-operated electroluminescent device as top electrode and bottom electrode, displays significant performance.

Measurement of the dynamic temperature response of electrocaloric effect in solid ferroelectric materials via thermoreflectance

ABSTRACT We propose a characterization method based on modulated thermoreflectance technique for measuring directly the electrocaloric (EC) effect. First, the EC response in BaTiO3-based multilayer capacitors (MLC) with Y5V specification was measured using thermoreflectance set-up. Further, the direct measurement method was implemented on P(VDF-TrFE) 55/45 thin films deposited on flexible PET substrate, where the frequency dependence of the EC response in these films was investigated. It was noted that the P(VDF-TrFE) EC temperature responses depend on the operation voltage frequency, thus we considered three frequency ranges using square voltage waveform. Three distinct types of EC temperature variation responses were observed depending on the waveform frequency range. In addition, the EC temperature variation of the thin film with a thickness of 1.4 µm was measured via thermoreflectance. The data reveal a large EC effect occurring at room temperature where a temperature change ΔT = 1.14°C was induced under a field of 82 MV/m.

Modeling the effect of hatched grounds on the radio-frequency performance of microstrip lines on flexible substrate

Cross-hatching of PCB grounds refers to a process in which certain ground planes appear as copper lattices; regular openings are placed at regular intervals. Nowadays, the efficacy of ground hatching on rigid PCBs is minimal. However, it is becoming essential for flexible hybrid electronics. Utilizing hatched grounds for flexible applications could offer some benefits. Hatched grounds can perform dual roles, act as ground surfaces, and offer structural support. Hatched grounds are more durable for bending and stretching applications. Also, hatched grounds are desirable in terms of material conservation. In this paper, we focus on studying how hatched grounds affect the RF performance of a straight microstrip line. Simulations show that cross-hatched grounds with more than 50% filling produces good radio-frequency performance. We will study the effect hatching pattern as well as the density of the hatching on the RF performance of the microstrips. The theoretical modeling is considered in this work and fabricating aerosol jet silver ink microstrip lines on PET substrates will be considered as an extension of this work.

Flexible liquid crystal micro-lens arrays for curved integral imaging 2D/3D convertible display

ABSTRACT Glasses-free three-dimensional (3D) displays are being regarded as the key to the future of display that will redefine the display industry. Inspired by the curved screen, liquid crystal micro-lens arrays (LC MLAs) on flexible PET substrate with a radius of curvature of 5 cm was achieved. For demonstration, an integral imaging-based 2D/3D convertible display system is proposed by using the flexible LC MLAs (FLC MLAs) to switch its operation mode between 2D and 3D modes. When the FLC MLAs with an applied voltage are in the system, the prototype renders a matched 3D image and works in 3D mode. When the FLC MLAs do not have an applied voltage, the FLC MLAs are equivalent to glass, and the display system works in 2D mode. In addition, we also demonstrated that the FLC MLAs have a wider viewing angle than the flat integral imaging 3D display system. The depth of field ranges from 6.78 to 210.12 mm under low operating voltages of 3.4 to 3.1 Vrms, respectively. With its low voltage, thin structure, and adjustable focal length form factors, the developed display system can be integrated with off-the-shelf purchased flat panels, making it a promising option for portable electronics.

Printable and Flexible Humidity Sensor Based on Graphene -Oxide-Supported MoTe2 Nanosheets for Multifunctional Applications.

This study focuses on a novel humidity sensor composed of graphene-oxide (GO)-supported MoTe2 nanosheets. Conductive Ag electrodes were formed on PET substrates by inkjet printing. A thin film of GO-MoTe2 was deposited on the Ag electrode used for adsorbing humidity. The experiment's results demonstrate that MoTe2 are attached to GO nanosheets uniformly and tightly. The capacitive output of the sensors with various ratios of GO/MoTe2 has been tested for different levels of humidity (11.3-97.3%RH) at room temperature (25 °C). As a consequence, the obtained hybrid film exhibits superior sensitivity (94.12 pF/%RH). The structural integrity and interaction of different components were discussed to afford the prominent humidity sensitivity performance. Under the bending condition, the output curve of the sensor has no obvious fluctuation. This work provides a low-cost way to build flexible humidity sensors with high-performance in environmental monitoring and healthcare.

P‐12.6: The application study of coated polarizer for TFT‐LCD panels

For TFT‐LCD industries, polarizer films are essential components, which directly determine the image quality of panels. The market proposes new trends of thin thickness and large size for TFT‐LCD panels, including applying polarizer films. The technology of coating linear polarizer could readily realize these demands and own the potential of being directly fabricated on glass substrates. Herein, we study the preparation process of coating a polarizer on a PET substrate and aim to enhance the optical performance. The coated polarizer with the polarization degree of 99.9% was successfully fabricated and applied at the 32‐inch TFT‐LCD panels with the contrast ratio of 1200. This technology exhibits a great application potential for next‐generation polarizer films be integrated on liquid crystal cell.

SnS-RGO Hybrid Nanosheets as High Performance Flexible Photodetectors and Visible-Light Photocatalysts

A straightforward solvothermal technique was used to create tin monosulfide (SnS) nanosheets that were reduced graphene oxide (RGO) bonded. On the folded RGO surface, it was discovered that the 2D SnS nanosheets had several layers that were evenly distributed. When exposed to visible light, a flexible photodetector made of PET substrate exhibits a 1.4 mA W−1 optical response, 3.5 × 107 Jones detection rate, and quick rise and fall times. (τ rise = τ decay = 0.08 s). When exposed to visible light, the methylene blue’s (MB) photocatalytic breakdown was used to test the photocatalytic performance of the synthesized SnS-RGO hybrid nanosheets. The fact that almost all of the MB dissolved in under one hour suggested that SnS-RGO nanosheets make promising high-performance photocatalysts.

Endowment of omniphobicity and exceptional bendability to a wear-resistant POSS coating

Coating of a new polyhedral oligomeric silsesquioxane, GMPOSS bearing two 3-glycidyloxypropyl (G) and six 3-methacryloxypropyl (M) groups, is highly wear-resistant but has no oil- or water-repellency and limited bendability. To render omniphobicity, perfluorinated poly(propylene oxide) (FP) bearing a terminal carboxyl group (FP-COOH) is grafted onto a fraction of the GMPOSS molecules to yield F-GMPOSS, a mixture of GMPOSS and GMPOSS-FP. Subsequent photocuring of a liquid film of F-GMPOSS that contains 2.6 wt% of fluorine produces a highly transparent coating with superior dynamic de-wetting properties. To improve the coating’s bendability, an innovative method for composite making is developed. A flexible porous poly(vinylidene fluoride-co-hexafluoropropylene) (PVDFP) scaffold is prepared first on a poly(ethylene terephthalate) (PET) substrate. F-GMPOSS containing photoinitiators are then infused into the PVDFP pores and photocured to produce a composite coating. At a thickness of 20 μm, the composite can fold, without crack or peel, 500 times on either the inner or outer side of its PET substrate around a rod of a diameter of 2 mm. The coating also has a transmittance of 95 ± 2% at 500 nm, a low surface energy of 11.8 ± 1.6 mJ/m2, and an impressive hardness of 0.80 ± 0.02 GPa. Its superior ink contraction capability remains intact after 100 abrasions with steel wool. While the methods for rendering antismudge properties and flexibility can be used to prepare other materials and coatings, the F-GMPOSS coating and the F-GMPOSS/PVDFP composite coating are of practical value and may be used as the encapsulating layer for foldable touchscreens, for example.

Surfactant-free emulsion of epoxy resin/sodium alginate for achieving robust underwater superoleophobic coating via a combination of phase separation and biomineralization

Underwater superoleophobic coatings exhibit promising prospects in the field of oil contamination resistance. However, their poor durability, stemming from the fragile structures and unstable hydrophilicity, greatly restricted their development. In this report, we proposed a novel strategy of combination water-induced phase separation and biomineralization to prepare the robust underwater superoleophobic epoxy resin-calcium alginate (EP-CA) coating by utilizing a surfactant-free emulsion of epoxy resin/sodium alginate (EP/SA). The EP-CA coating not only exhibited excellent adhesion to various substrates, but also had remarkable resistance to the physical/chemical attacks such as abrasion, acid, alkali and salt. It could also protect the substrate (e.g., PET substrate) from the damage of organic solution and the fouling of crude oil. This report provides a new perspective to fabricate robust superhydrophilic coating with a facile way.

Defining the zerogap: cracking along the photolithographically defined Au–Cu–Au lines with sub-nanometer precision

Abstract Cracks are formed along the photolithographically pre-determined lines with extremely high yield and repeatability, when Cu clusters are introduced between planarized Au thin films sequentially deposited on a PET substrate. These clusters act as nanometer-sized spacers preventing the formation of contiguous metallic bond between the adjacent Au layers which will render prepatterned-cracking impossible. While the effective gap width is initially zero in the optical sense from microwaves all the way to the visible, outer-bending the PET substrate allows the gap width tuning into the 100 nm range, with the stability and controllability in the ranges of 100 s and Angstrom-scale, respectively. It is anticipated that our wafer-scale prepatterned crack technology with an unprecedented mixture of macroscopic length and Angstrom-scale controllability will open-up many applications in optoelectronics, quantum photonics and photocatalysis.

The Effect of Electro-Induced Multi-Gas Modification on Polymer Substrates’ Surface Structure for Additive Manufacturing

We investigated the effect of electro-induced multi-gas modification (EIMGM) duration on the adhesion and wear resistance of PET and LDPE polymer substrates used in the printing industry. It was found that EIMGM increases the polar component and the complete free surface energy from 26 to 57 mJ/m2 for LDPE and from 37 to 67 mJ/m2 for PET (due to the formation of oxygen-containing groups on the surface of the materials). Although the degree of textural and morphological heterogeneity of the modified LDPE increased more than twice compared to the initial state, it is not still suitable for application as a substrate in extrusion 3D printing. However, for PET, the plasma-chemical modification contributed to a significant increase (~5 times) in filament adhesion to its surface (due to chemical and morphological transformations of the surface layers) which allows for using the FFF technology for additive prototyping on the modified PET-substrates.

Effect of thermal annealing on electrochemical and morphological properties of printed NiO electrodes for flexible asymmetric micro-supercapacitor applications

We report the effects of thermal annealing on screen-printed NiO electrodes for asymmetric battery-type supercapacitors on flexible substrates. Ni(OH)2 was synthesized and annealed at 300 °C, 400 °C, 500 °C, 600 °C, 700 °C and 800 °C to obtain six morphologically diverse NiO samples. FE-SEM, XRD, BET, and four-probe measurements were used to investigate their morphology, crystallinity, surface area, and conductivity, respectively. Six symmetric supercapacitors were screen-printed on a PET substrate with 1 M H2SO4 electrolyte to probe their electrochemical properties. NiO annealed at 400 °C (NiO-400) demonstrated the highest areal capacitance of 19.54 mF/cm2 coupled with reduced charge-transfer resistance, consistent with the highly porous yet continuous structure observed via FE-SEM and BET surface analysis. With this, an inter-digital asymmetric supercapacitor with NiO-400 cathode and graphene anode was fabricated to demonstrate high areal capacitance of 26.42 mF/cm2, a wide potential window of 1.5 V (at 97.3% coulombic efficiency) and excellent flexibility with 96.4% retention (180°) after 1000 cycles.

Polymeric Nanofibriller Matrix on ITO Substrate for Flexible Chemical Sensing Applications

The authors present here a facile electrochemical approach to synthesize Poly(Aniline) nanofibriller matrix on ITO coated PET substrate for development of wearable or embeddable sensors. Electrochemical parameters were optimized for even diametric synthesis and controlled length of Poly (Aniline)) nanofibers. A three – step chrono potentiometric deposition was found to be efficient for the synthesis of the matrix. Precise tuning of galvanic conditions during the synthesis process was highly effective and repetitive towards controlling the nucleation of Poly (Aniline) seeds on the substrate that serves as the basis of nanofibers with presumable diameter range. Charge conduction behaviour of the matrix was studied via Linear Sweep Voltammetry and a semiconducting nature was observed. The synthesized nanofibrillar sensor platforms were subjected to Scanning Electron Microscopy (SEM), UV-VIS Spectroscopy and FTIR spectroscopy for elucidation of morphological and structural aspects. The distribution of nanofibers network throughout the substrate was uniform and dendritic. Flexibility characteristics of the sensors were studied by bending the sensor to different radii and in-situ monitoring of resistance. The synthesized sensor platforms were subjected to NO2 sensing in chemiresistive mode under dynamic conditions to investigate the applicability of the same under real-time applications. Upon exposure to different concentrations of NO2, the devices exhibit a rapid response at concentrations as low as 1 ppm. The betterment in overall sensing behaviour in comparison to conventional thin film type sensors could be attributed to the one-dimensional structure of nanofibers leading to effective diffusion on analyte molecules and low scattering loss during charge transport. These flexible sensors can be interesting for novel mobile applications.

Oxide/Metal/Oxide 구조의 유연하고 투명한 히터

Optically transparent and electrically conductive films were investigated for the flexible and transparent heaters. Metal (Ag), silver nanowires (AgNWs) and metal oxide (ITO or ZnO) were employed to form the various types of transparent heaters. A single-layered ITO, metal hybrid AgNWs (ZnO/AgNWs) and ZnO/Ag/ZnO composite were manufactured on PET substrates. Each case was tailored by large-scale device (150 mm x 100 mm).BRFor each structure, visible light transmittance, electrical conductivity, and heating performances were investigated to show the enhanced performances from the ZnO/Ag/ZnO composite, which showed the excellent transmittable (77% at wavelength of 550 nm) and outperforming heating performances to reach 146°C with fast heating speed. The improved performances are mainly attributed to the structure of ZnO/Ag/ZnO, where the thin Ag governs the electrical property with good optical feature. This study suggests that the ZnO/Ag/ZnO transparent heater has the excellent optical and electrical properties with good flexibility and affordable scalability to enlighten the large-scale and flexible heating applications.

Light-driven, ultra-sensitive and multifunctional ammonia wireless sensing system by plasmonic-functionalized Nb2CTx MXenes towards smart agriculture

With the rapid development of the Internet of Things (IoT), the smart agriculture has played a key role in modern society. For the purpose of constructing smart agriculture systems, the distributed sensors should be applied, especially for the ammonia gas (NH3) sensing devices with versatile functions. However, the traditional NH3 sensors with the resistive heater severely restrict the development of room-temperature gas sensors, flexible electronics and integration of circuits in the practical application of IoT. Herein, a light-driven NH3 sensor based on plasmonic-functionalized metal carbides/nitrides (MXenes) is developed to achieve the room-temperature, ultra-sensitive NH3 sensing towards smart agriculture. The in-situ oxidized niobium carbide (HT-Nb2CTx) serves as NH3 adsorption sites as well as conductive layers on flexible PET substrates to induce a large charge transfer. Density functional theory (DFT) calculations further verify that NH3 adsorption energy is remarkably increased on in-situ oxidized sites. Most noteworthy is that plasmonic Au nanorods, as the local heating sites of 20 nm replace the extra resistive heater to promote the NH3 sensing reaction under 980 nm light, taking the advantage of photo-thermal effects of localized surface plasmon resonance (LSPR). Such Au/HT-Nb2CTx based gas sensors exhibits the trace NH3 sensing ability with a low limit of detection (LOD=500 ppb) and full recovery. The sensitivity (80 % for 100 ppm of NH3) is more than two times higher compared with the counterparts without Au NRs. A light-driven, portable NH3 sensing and alarming system consisted with the gas/temperature/humidity sensors is wirelessly connected to a mobile phone to realize the “round-the-clock” environment monitoring. This proof of the sensing device using Au/HT-Nb2CTx exhibits the potential application in the next-generation NH3 monitoring system in the future smart agriculture.

Fast-speed, Highly Sensitive, Flexible Humidity Sensors Based on a Printable Composite of Carbon Nanotubes and Hydrophilic Polymers

Carbon nanotubes (CNTs) are a promising material for humidity sensors and wearable electronics due to their solution capability, good flexibility, and high conductivity. However, the performance of CNT-based humidity sensors is limited by their low sensitivity and slow response. Herein CNTs and hydrophilic polymers were mixed to form a composite. The hydrophilicity of the polymers and the network structure of the CNTs empowered the humidity sensors with a high response of 171% and a fast response/recovery time of 23 s/10 s. Owing to the sticky and flexible polymers, the humidity sensors showed strong adhesion to the PET substrate and exhibited outstanding bending durability. Furthermore, the flexible humidity sensor was applied to monitor human breathing and detect finger movements and handshaking.