Iterative SuFEx approach for sequence-regulated oligosulfates and its extension to periodic copolymers.

The synthesis of sequence-regulated oligosulfates has not yet been established due to the difficulties in precise reactivity control. In this work, we report an example of a multi-directional divergent iterative method to furnish oligosulfates based on a chain homologation approach, in which the fluorosulfate unit is regenerated. The oligosulfate sequences are determined by high resolution mass spectrometry of the hydrolyzed fragments, and polysulfate periodic copolymers are synthesized by using oligomeric bisfluorosulfates in a bi-directional fashion. The synthetic utility of this iterative ligation is demonstrated by preparing crosslinked network polymers as synthetic adhesive materials.

Biomass-derived optically clear adhesives for foldable displays.

Acrylic pressure sensitive adhesives (PSAs) are the most widely used and play a crucial role in ensuring the stable operation of foldable displays. With a focus on product sustainability, numerous studies have aimed to enhance eco-friendliness of acrylic PSAs. However, few studies specifically address the development of environmentally friendly acrylic PSAs for foldable devices. In this work, we synthesized new monomers by modifying citronellol, a terpenoid, for use as functional monomers and low glass transition temperature (Tg) monomers in acrylic optical clear adhesives (OCAs). We prepared OCAs using these monomers via an environmentally friendly visible-light-driven polymerization process due to its greater energy efficiency and reduced harm to humans, as opposed to the ultraviolet light that is normally used in conventional photopolymerization processes. Their properties were confirmed through rheological analysis. The resultant OCAs exhibit low Tg, appropriate storage modulus across a wide temperature range, reliable adhesion force to various substrates, and decent creep and recovery properties. These characteristics indicate their potential to enhance the eco-friendliness of foldable devices.

Visible-Light-Driven Rapid 3D Printing of Photoresponsive Resins for Optically Clear Multifunctional 3D Objects.

Light-driven 3D printing is gaining significant attention for its unparalleled build speed and high-resolution in additive manufacturing. However, extending vat photopolymerization to multifunctional, photoresponsive materials poses challenges, such as light attenuation and interference between the photocatalysts (PCs) and photoactive moieties. This study introduces novel visible-light-driven acrylic resins that enable rapid, high-resolution photoactive 3D printing. The synergistic combination of a cyanine-based PC, borate, and iodonium coinitiators (HNu 254) achieves an excellent printing rate and feature resolution under low-intensity, red light exposure. The incorporation of novel hexaarylbiimidazole (HABI) crosslinkers allows for spatially-resolved photoactivation upon exposure to violet/blue light. Furthermore, a photobleaching mechanism inhibited by HNu 254 during the photopolymerization process results in the production of optically-clear 3D printed objects. Real-time Fourier transform infrared spectroscopy validates the rapid photopolymerization of the HABI-containing acrylic resin, whereas mechanistic evaluations reveal the underlying dynamics that are responsible for the rapid photopolymerization rate, wavelength-orthogonal photoactivation, and observed photobleaching phenomenon. Ultimately, this visible-light-based printing method demonstrates: (i) rapid printing rate of 22.5 mm h-1, (ii) excellent feature resolution (≈20 µm), and (iii) production of optically clear object with self-healing capability and spatially controlled cleavage. This study serves as a roadmap for developing next-generation "smart" 3D printing technologies.

Realizing Cross-linking-free Acrylic Pressure-Sensitive Adhesives with Intensive Chain Entanglement through Visible-Light-Mediated Photoiniferter-Reversible Addition-Fragmentation Chain-Transfer Polymerization.

A versatile and simplified synthesis scheme for intensively entangled acrylic pressure-sensitive adhesives (PSAs) was developed in this study by leveraging visible-light-driven controlled radical polymerization (photoiniferter/reversible addition-fragmentation chain-transfer polymerization) of acrylic copolymers under a controlled manner; the approach was differentiated by a single factor; molecular weight (Mw up to 2.8 MDa) with identical compositions. By manipulating Mw up to ultra-high ranges, PSAs with diversified viscoelastic properties were prepared and then assessed with a focus on realizing PSAs with a maximized degree of entanglement per chain through domination of high Mw contents, to help achieve excellent cohesiveness without a reinforcing cross-linking network. Moreover, fully linear solvent-soluble poly(acrylate)s were synthesized to facilitate reprocessing and reuse, highlighting the sustainability of the devised method and, consequently, its potential to be applied for effectively reducing industrial or daily waste.

Robust 2D layered MXene matrix-boron carbide hybrid films for neutron radiation shielding.

Large-scale fabrication of neutron-shielding films with flexible or complex shapes is challenging. Uniform and high boron carbide (B4C) filler loads with sufficient workability are needed to achieve good neutron-absorption capacity. Here, we show that a two-dimensional (2D) Ti3C2Tx MXene hybrid film with homogeneously distributed B4C particles exhibits high mechanical flexibility and anomalous neutron-shielding properties. Layered and solution-processable 2D Ti3C2Tx MXene flakes serve as an ideal robust and flexible matrix for high-content B4C fillers (60 wt.%). In addition, the preparation of a scalable neutron shielding MXene/B4C hybrid paint is demonstrated. This composite can be directly integrated with various large-scale surfaces (e.g., stainless steel, glass, and nylon). Because of their low thickness, simple and scalable preparation method, and an absorption capacity of 39.8% for neutrons emitted from a 241Am-9Be source, the 2D Ti3C2Tx MXene hybrid films are promising candidates for use in wearable and lightweight applications.

Facile and Efficient Production of Biomass-Derived Isosorbide Dioxides via Epoxidation Using In situ-generated DMDO under Ultrasonication.

Herein, we present a facile synthetic process for producing biomass-derived isosorbide (ISB) dioxides using dimethyl dioxirane (DMDO) as an efficient oxidizing agent, which was generated in situ from acetone and KHSO5 . To achieve high conversion and product yield, the KHSO5 concentration, KHSO5 flow rate, and reaction temperature were optimized. Under the optimal conditions, rapid and efficient epoxidation using the in situ-generated DMDO was observed under ultrasonication, yielding the desired product within 35 min at 0 °C. This study offers a convenient and efficient method for generating biomass-derived ISB building blocks, which have significant potential for the fabrication of bioplastics.

Enhancement of electrochemical detection performance towards 2,4,6-trinitrotoluene by a bottom layer of ZnO nanorod arrays.

The ZnO nanostructure layers have been widely investigated as electrodes for sensors due to their intrinsic advantages such as high active area and low cost. In this work, to enhance the detection properties of ZnO nanostructural electrodes, self-organized ZnO nanorod arrays were synthesized using the chemical bath deposition (CBD) method on FTO glasses and ZnO nanoparticles. The fabricated ZnO electrodes on the two different substrates were characterized by SEM, TEM, XRD, and XPS. Subsequently, the detection performance of ZnO nanorod electrodes was electrochemically measured in a 2,4,6-trinitrotoluene (2,4,6-TNT) solution by CV and EIS. The differences in current densities between the ZnO electrodes were determined by the width of the ZnO nanorods, resulting in a ∼45% higher detection efficiency with F-CBD (the ZnO nanorods on FTO) electrodes compared to S-CBD (the ZnO nanorods on ZnO nanoparticles) electrodes.

Visible-Light-Curable Acrylic Resins toward UV-Light-Blocking Adhesives for Foldable Displays.

Current technological advances in the organic light-emitting diode panel design of foldable smartphones demand advanced adhesives with UV-blocking abilities, beyond their conventional roles of bonding objects and relieving deformation stress. However, optically clear adhesives (OCAs) with UV-blocking ability cannot be prepared using conventional UV-curing methods relying on a photoinitiator. Herein, a new acrylic resin that can be efficiently cured using visible light without oxygen removal is presented, which may be used to develop UV-blocking OCAs for use in current flexible displays. A novel photocatalyst and a specific combination of additives facilitate sufficiently rapid curing under visible light in the presence of UV-absorbers. Only a very small amount of the highly active photocatalyst is required to prepare UV-blocking OCA films with very high transparency in the visible region. Using this system, a UV-blocking OCA that nearly meets the specifications of an OCA used in commercialized foldable smartphones is realized. This technology can also be utilized in other applications that require highly efficient visible light curing, such as optically clear resins, dental resins, and 3D/4D-printable materials.

Artificial Neural Networks for Predicting Plastic Anisotropy of Sheet Metals Based on Indentation Test.

This paper mainly proposes two kinds of artificial neural network (ANN) models for predicting the plastic anisotropy properties of sheet metal using spherical indentation test, which minimizes measurement time, costs, and simplifies the process of obtaining the anisotropy properties than the conventional tensile test. The proposed ANN models for predicting anisotropic properties can replace the traditional complex dimensionless analysis. Moreover, this paper is not limited to the prediction of yield strength anisotropy but also further accurately predicts the Lankford coefficient in different orientations. We newly construct an FE spherical indentation model, which is suitable for sheet metal in consideration of actual compliance. To obtain a large dataset for training the ANN, the constructed FE model is utilized to simulate pure and alloyed engineering metals with one thousand elastoplastic parameter conditions. We suggest the specific variables of the residual indentation mark as input parameters, also with the indentation load-depth curve. The profile of the residual indentation, including the height and length in different orientations, are used to analyze the anisotropic properties of the material. Experimental validations have been conducted with three different sheet alloys, TRIP1180 steel, zinc alloy, and aluminum alloy 6063-T6, comparing the proposed ANN model and the uniaxial tensile test. In addition, machine vision was used to efficiently analyze the residual indentation marks and automatically measure the indentation profiles in different orientations. The proposed ANN model exhibits remarkable performance in the prediction of the flow curves and Lankford coefficient of different orientations.

Numerical Simulation of the Effects of Scanning Strategies on the Aluminum Evaporation of Titanium Alloy in the Electron Beam Cold Hearth Melting Process.

In the production of titanium alloy, the electron beam cold hearth melting (EBCHM) process is commonly used due to its effectiveness and the high quality of the end product. However, its main drawback is the significant loss of elements such as aluminum (Al) due to evaporation under the vacuum environment. Numerical coupled thermal-flow models were here developed to investigate the effects of scanning strategies on Al loss in a titanium alloy during EBCHM. The validation model was successful in comparison with previously published experimental data. The Al mass fraction results at the outlet of the water-cooled hearth were strongly influenced by changes in the applied scanning strategies. The results indicated that the Al mass fraction loss could be reduced by using the full-hearth scanning strategies.

Synthesis of Waterborne Polyurethane Using Phosphorus-Modified Rigid Polyol and its Physical Properties.

In this study, a phosphorous-containing polyol (P-polyol) was synthesized and reacted with isophorone diisocyanate (IPDI) to produce water-dispersed polyurethane. To synthesize waterborne polyurethanes (WPUs), mixtures of P-polyol and polycarbonate diol (PCD) were reacted with IPDI, followed by the addition of dimethylol propionic acid, to confer hydrophilicity to the produced polyurethane. An excess amount of water was used to disperse polyurethane in water, and the terminal isocyanate groups of the resulting WPUs were capped with ethylene diamine. P-polyol:PCD molar ratios of 0.1:0.9, 0.2:0.8, and 0.3:0.7 were used to synthesize WPUs. The films prepared by casting and drying the synthesized WPUs in plastic Petri dishes were used to test the changes in physical properties induced by changing the P-polyol:PCD molar ratio. The experimental results revealed that the tensile strength of PU-10, the WPU with a P-polyol:PCD molar ratio of 0.1:0.9, was 16% higher than that of the reference P-polyol-free WPU sample. Moreover, the thermal decomposition temperature of PU-10 was 27 °C higher than that of the reference sample.

Visible-Light-Curable Solvent-Free Acrylic Pressure-Sensitive Adhesives via Photoredox-Mediated Radical Polymerization.

Owing to their excellent properties, such as transparency, resistance to oxidation, and high adhesivity, acrylic pressure-sensitive adhesives (PSAs) are widely used. Recently, solvent-free acrylic PSAs, which are typically prepared via photopolymerization, have attracted increasing attention because of the current strict environmental regulations. UV light is commonly used as an excitation source for photopolymerization, whereas visible light, which is safer for humans, is rarely utilized. In this study, we prepared solvent-free acrylic PSAs via visible light-driven photoredox-mediated radical polymerization. Three α-haloesters were used as additives to overcome critical shortcomings, such as the previously reported low film curing rate and poor transparency observed during additive-free photocatalytic polymerization. The film curing rate was greatly increased in the presence of α-haloesters, which lowered the photocatalyst loadings and, hence, improved the film transparency. These results confirmed that our method could be widely used to prepare general-purpose solvent-free PSAs-in particular, optically clear adhesives for electronics.

Redox-Initiated Reversible Addition-Fragmentation Chain Transfer (RAFT) Miniemulsion Polymerization of Styrene using PPEGMA-Based Macro-RAFT Agent.

Redox-initiated reversible addition-fragmentation chain transfer (RAFT) miniemulsion polymerizations are successfully conducted with an employment of trithiocarbonate-based macro-RAFT agents and surfactant. Two macro-RAFT agents-hydrophilic poly(poly(ethylene glycol) methyl ether methacrylate) (PPEGMA27 ) and amphiphilic poly(poly(ethylene glycol) methyl ether methacrylate)-b-polystyrene (PPEGMA27 -b-PS33 )- are examined for the miniemulsion polymerization of styrene. The use of PPEGMA27 (in the presence of sodium dodecyl sulfate (SDS)) results in a slow polymerization rate with a broad particle size. In the absence of SDS, the use of PPEGMA27 -b-PS33 results in a broad particle size distribution due to its inability to form uniform initial droplets whereas the same amphiphilic block copolymer in the presence of SDS yields resulting products with a uniform particle size distribution. The latter exhibits a fashion of controlled polymerization with a high consumption of monomer (98% in 100 min) and a narrow molecular weight distribution throughout the polymerization. This is attributed to the formation of uniform droplets facilitated by SDS in a miniemulsion. The amphiphilic macro-RAFT agent is able to anchor efficiently on the monomer droplet or particle/water interface and form stabilized particles of well-defined PPEGMA27 -b-PS block copolymer, confirmed using dynamic light scattering and transmission electron micrographs.

Flame Retardant Submicron Particles via Surfactant-Free RAFT Emulsion Polymerization of Styrene Derivatives Containing Phosphorous.

The reversible addition-fragmentation chain transfer (RAFT) emulsion polymerization of diethyl-(4-vinylbenzyl) phosphate (DEVBP) was performed using PEG-TTC as a macro RAFT agent. PEG-TTC (MW 2000, 4000) was synthesized by the esterification of poly (ethylene glycol) methyl ether with a carboxylic-terminated RAFT agent, composed a hydrophilic poly (ethylene glycol) (PEG) block and a hydrophobic dodecyl chain. The RAFT emulsion polymerization of DEVBP was well-controlled with a narrow molecular size distribution. Dynamic light scattering and confocal laser scanning microscopy were used to examine the PEG-b-PDVBP submicron particles, and the length of the PEG chain (hydrophilic block) was found to affect the particle size distribution and molecular weight distribution. The submicron particle size increased with increasing degree of polymerization (35, 65, and 130), and precipitation was observed at a high degree of polymerization (DP) using low molecular weight PEG-TTC (DP 130, A3). The flame retardant properties of the PEG-b-PDVBP were evaluated by thermogravimetric analysis (TGA) and micro cone calorimeter (MCC). In the combustion process, the residue of PEG-b-PDEVBP were above 500 °C was observed (A1 ~ B3, 27 ~ 38%), and flame retardant effect of PEG-b-PDEVBP submicron particles/PVA composite were confirmed by increasing range of temperature and decreasing total heat release with increasing contents of PEG-b-PDEVBP. The PEG-b-PDEVBP submicron particles can provide flame retardant properties to aqueous, dispersion and emulsion formed organic/polymer products.

Pyridinium-Functionalized Ionic Metal-Organic Frameworks Designed as Bifunctional Catalysts for CO2 Fixation into Cyclic Carbonates.

Ionic metal-organic frameworks (MOFs) offer a new platform to design and construct complete heterogeneous bifunctional catalytic systems for the chemical fixation of CO2 with epoxides. Herein, we developed a series of bifunctional pyridinium ionic MOF heterogeneous catalysts (66Pym-RXs and 67BPym-MeI) by the postsynthetic N-alkylation of noncoordinated pyridine sites in porous MOFs. The synergetic catalytic effect of acidic sites with nucleophilic anions in the ionic MOF significantly enhanced the catalytic activity toward the cycloaddition of CO2 with epoxides to produce cyclic carbonates under cocatalyst-free and solvent-free mild conditions. The catalytic activity of ionic MOFs is easily tuned by the introduction of different alkyl groups into pyridinium cations and halide ions. The 66Pym-iPrI catalyst displayed the highest catalytic performance in terms of the turnover number value for the synthesis of cyclic carbonates. The proposed alternative method provides the means of developing functional N-heterocyclic groups for the new design of bifunctional ionic MOFs as potential heterogeneous catalysts for CO2 fixation applications.

Exploiting Dynamic Opening of Apertures in a Partially Fluorinated MOF for Enhancing H2 Desorption Temperature and Isotope Separation.

Deuterium has been recognized as an irreplaceable element in industrial and scientific research. However, hydrogen isotope separation still remains a huge challenge due to the identical physicochemical properties of the isotopes. In this paper, a partially fluorinated metal-organic framework (MOF) with copper, a so-called FMOFCu, was investigated to determine the separation efficiency and capacity of the framework for deuterium extraction from a hydrogen isotope mixture. The unique structure of this porous material consists of a trimodal pore system with large tubular cavities connected through a smaller cavity with bottleneck apertures with a size of 3.6 Å plus a third hidden cavity connected by an even smaller aperture of 2.5 Å. Depending on the temperature, these two apertures show a gate-opening effect and the cavities get successively accessible for hydrogen with increasing temperature. Thermal desorption spectroscopy (TDS) measurements indicate that the locally flexible MOF can separate D2 from anisotope mixture efficiently, with a selectivity of 14 at 25 K and 4 at 77 K.

Modified Epoxy Resin Synthesis from Phosphorus-Containing Polyol and Physical Changes Studies in the Synthesized Products.

Epoxy resins are commonly used to manufacture the molding compounds, reinforced plastics, coatings, or adhesives required in various industries. However, the demand for new epoxy resins has increased to satisfy diverse industrial requirements such as enhanced mechanical properties, thermal stability, or electrical properties. Therefore, in this study, we synthesized new epoxy resin (PPME) by modifying phosphorous-containing polyol. The prepared resin was analyzed and added to epoxy compositions in various quantities. The compositions were cured at high temperatures to obtain plastics to further test the mechanical and thermal properties of the epoxy resin. The measured tensile and flexural strength of epoxy compositions were similar to the composition without synthesized epoxy resin. However, the heat release rates of the compositions exhibited tendencies of a decrease proportional to the amount of PPME.

Synthesis of Benzene Tetracarboxamide Polyamine and Its Effect on Epoxy Resin Properties.

Epoxy resins have found various industrial applications in high-performance thermosetting resins, high-performance composites, electronic-packaging materials, adhesives, protective coatings, etc., due to their outstanding performance, including high toughness, high-temperature performance, chemical and environmental resistance, versatile processability and adhesive properties. However, cured epoxy resins are very brittle, which limits their applications. In this work, we attempted to enhance the toughness of cured epoxy resins by introducing benzene tetracarboxamide polyamine (BTCP), synthesized from pyromellitic dianhydride (PMDA) and diamines in N-methyl-2-pyrrolidone (NMP) solvent. During this reaction, increased viscosity and formation of amic acid could be confirmed. The chemical reactions were monitored and evidenced using ¹H-NMR spectroscopy, FT-IR spectroscopy, water gel-phase chromatography (GPC) analysis, amine value determination and acid value determination. We also studied the effect of additives on thermomechanical properties using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamical mechanical analysis (DMA), thermomechanical analysis (TMA) and by measuring mechanical properties. The BTCP-containing epoxy resin exhibited high mechanical strength and adhesion strength proportional to the amount of BTCP. Furthermore, field-emission scanning electron microscopy images were obtained for examining the cross-sectional morphology changes of the epoxy resin specimens with varying amounts of BTCP.

Evaluating FINDRISC as a screening tool for type 2 diabetes among overweight adults in the PREVIEW:NZ cohort.

AIMS: This study aimed to evaluate the efficacy of a high (≥12) Finnish diabetes risk (FINDRISC) score in identifying undiagnosed prediabetes and type 2 diabetes (T2D) in an New Zealand population of overweight and obese individuals, across a variety of ethnic groups. METHODS: We estimated the efficacy of elevated FINDRISC scores in predicting prediabetes and T2D in 424 overweight adults with no prior diagnosis recruited for the PREVention of diabetes through lifestyle Interventions in Europe and Worldwide (PREVIEW) study. All participants who completed the FINDRISC questionnaire during a pre-screening phase with a score of ≥12 were then screened using a 2h oral glucose tolerance test (2h-OGTT) to identify undiagnosed dysglycaemia. RESULTS: Of the 424 participants, 65% (n=280) were pre-diabetic and 7% (n=32) had undiagnosed T2D. A higher FINDRISC score was significantly associated with prediabetes and T2D (P=0.02). There was a significant association between ethnicity and glycaemic status (normal vs prediabetes/T2D, P=0.02). Increasing the FINDRISC cut-off to ≥15 resulted in a non-significant increase in the proportion of participants correctly classified with dysglycaemia. ROC-AUC=0.6 with sensitivity=0.6026 (95% CI: 0.5459-0.6573) and specificity=0.5536 (95% CI: 0.4567-0.6476). Isolated impaired fasting glucose (IFG) was more efficient in predicting dysglycaemia than isolated impaired glucose tolerance (IGT). CONCLUSIONS: The FINDRISC questionnaire is a useful and efficacious screening tool to identify unknown prediabetes and T2D in overweight New Zealanders, particularly in Maori individuals.

A foolproof method for phase transfer of metal nanoparticles via centrifugation.

Our new approach using centrifugal force provides a simple and foolproof method for the phase transfer of metal nanoparticles to organic solvents. The centrifugation following functionalization by thiol-containing molecules on the metal nanoparticles in water pushed the metal nanoparticles down to the chloroform compulsorily.