Bond Conversion Research Articles

Non‐Isocyanate Carbamate Acrylates: Synthesis, Characterization, and Applications in UV 3D Printing

ABSTRACTIn this paper, two synthetic routes for non‐isocyanate carbamate acrylates (CAs) were explored. Four amino alcohols reacted with ethylene carbonate respectively forming carbamate alcohols. Additionally, carbamate amines were synthesized through the reaction of diethylene glycol with dimethyl carbonate, followed by the reaction of 4‐methylcyclohexane‐1,3‐diamine. Five kinds of CAs were synthesized via oxa‐Michael addition of carbamate alcohols and aza‐Michael reactions of carbamate amines with neopentyl glycol diacrylate (NPGDA), respectively. The resulting intermediates and final CAs were characterized by electrospray ionization high‐resolution mass spectrometry (ESI‐HRMS), 1H NMR, and FT‐IR spectroscopy. The photopolymerization kinetics of the CAs were investigated using FT‐IR spectroscopy. Under UV irradiation and initiation by 1 wt% 2‐isopropylthioxanthone (ITX) for 30 s, the double bond conversion of the CAs synthesized by oxa‐Michael addition were over 95%. The resulting CAs can be UV cured to form a transparent film with a gel content of 90%–95%, a hardness of 4–5 H, and a flexibility of 1 mm. A formulation consisting of 79 wt% CA2, 20 wt% NPGDA, and 1 wt% ITX was applied for 3D printing to produce various models with smooth surfaces, high precision, and excellent flexibility.

Bio-inspired carbon-based artificial muscle with precise and continuous morphing capabilities

Abstract In the face of advancements in micro-robotics, intelligent control, and precision medicine, artificial muscle actuation systems must meet demands for precise control, high stability, environmental adaptability, and high integration miniaturization. Carbon materials, with their lightweight, high strength, conductivity, and flexibility, show great potential for artificial muscles. Inspired by the butterfly's proboscis, we have developed a carbon-based artificial muscle, HsGDY-M, fabricated efficiently using an emerging hydrogen-substituted graphdiyne (HsGDY) film with an asymmetrical surface structure. This muscle features reversible, rapid, and continuously adjustable deformation capabilities similar to the butterfly's proboscis, triggered by the conversion of carbon bonds. The size of the HsGDY-M can be tuned by tailoring the HsGDY film width from ∼1 cm to 100 µm. Our research demonstrates HsGDY-M's stability and adaptability, maintaining performance at temperatures as low as -25°C. This artificial muscle was successfully integrated into a robotic mechanical arm, allowing it to swiftly adjust its posture and lift objects up to 11 times its own weight. Its beneficial responsiveness is transferable, enabling the transformation of “inert” objects like copper foil into actuators via surface bonding. Since its super sensitive and rapid deformation, HsGDY-M was applied to create a real-time tracking system for human finger bending movements, achieving real-time simulation and large-hand-to-small-hand control. Our study indicates that HsGDY-M holds significant promise for advancing smart robotics and precision medicine.

Polymerization kinetics of 3D-printed orthodontic aligners under different UV post-curing conditions

BackgroundThe purpose of the study was to measure the degree of conversion (DC) of direct-printed aligners (DPA) that were post-cured under ambient and nitrogen atmosphere at specific time intervals and investigate the kinetics of polymerization reaction of this material.MethodsA total of 48 aligners were produced in 4 printing series by a 3D printer with TC-85DAC resin (Graphy Inc). From each series of printing, 12 aligners were included. The aligners were divided into two groups according to their post-curing conditions. One group was post-cured under ambient air with the presence of oxygen and the other under a nitrogen atmosphere, both using the same UV post-curing unit recommended by the company. The aligners were post-cured at six different time intervals: 1, 2, 3, 5, 10, and 20 min. Each time interval included 8 aligners, with 2 aligners from each series. The DC of the cured aligners was measured by means of attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) through acquisition of the respective spectra for each UV-curing condition. Statistical analysis was performed to compare the results and differences within each atmosphere post-curing protocol, as well as between the different selected atmosphere conditions. Statistical significance level was set at p-value ≤ 0.05.ResultsPairwise analysis between post-curing protocols showed statistically significant differences only at the first minute of polymerization. Post-curing with nitrogen did not yield statistically significant results across different time intervals. Post-curing in ambient air showed some significant differences on the 1st and 2nd minute of the post-curing process.ConclusionsAlmost complete double bond conversion was observed. Significant differences were observed only during the first minute of polymerization under the nitrogen atmosphere.

Oxime esters: Potential alternatives to phosphine oxides, for overcoming oxygen inhibition in material jetting applications

Material jetting technology is emerging as a prominent technique within the additive manufacturing domain for printing multi-material objects. Despite its various advantages, including high printing resolution, oxygen inhibition remains the main issue for UV-curable materials. Oxime esters are interesting photoinitiators for this application due to their ability to undergo a photocleavage reaction followed by decarboxylation, limiting the diffusion of oxygen. A series of four commercially available oxime esters were studied as Type I photoinitiators, with the photoinitiating ability and photochemical properties of two of them never having been investigated before. Initially, their UV–visible absorption properties were studied, revealing significant absorption up to 420nm. Photopolymerization kinetic studies indicate that the oxime esters can outperformed benchmark photoinitiators such as phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO) by reaching around 80% of double bond conversion in 12µm layer under air (for O-16) against 60% for BAPO under the same conditions. Finally, the oxime esters were tested in 3D-inkjet printing applications, displaying highly promising results with tack-free surfaces.

Protective Coatings Based on the Organosilicon Derivatives of Fatty Acids Obtained by the Thiol-Ene Click Reaction.

This article describes the synthesis of a hydrophobic protective coating for concrete based on a silane derivative of fatty acids. The coating was obtained through a thiol-ene click addition reaction using methyl oleate and 3-mercaptopropyltrimethoxysilane in the presence of the photoinitiator 2,2-dimethoxy-2-phenylacetophenone (DMPA). This reaction proved to be more efficient compared with other tested (photo)initiators, considering the double bond conversion of oleate. The coating was applied to concrete using two methods: immersion and brushing. Both methods exhibited similar consumption of methyl oleate-based silane (UVMeS) at approximately 20 g/m2. The hydrophobic properties of the coatings were evaluated based on the contact angle, which for the modified surfaces was above 93°, indicating their hydrophobic nature. The penetration depth of the silane solution into the concrete was also studied; it was 5-7 mm for the immersion method and 3-5 mm for the brushing method. The addition of tetraethoxysilane (TEOS) to the silane solution slightly improved the barrier properties of the coating.

NIR‐induced upconversion‐assisted photopolymerization: Key factors, challenges, and future directions

AbstractNIR‐induced upconversion‐assisted photopolymerization has gained growing attention in the past two decades because of its numerous advantages over conventional UV/visible photopolymerization and two‐photon polymerization processes. However, research in this area is still in its early stages. To extend the practical application of NIR‐induced radiation curing, it is essential to optimize the factors affecting the photopolymerization reactions. Researchers have been constantly trying to improve these factors to tune the photo‐physical characteristics (luminescence intensity and color) of upconversion particles (UCPs), enhance curing depths and degree of double bond conversion (DC), and investigate the application of UCPs in emerging fields. In this review, first, a brief discussion of the upconversion mechanisms and upconversion efficiency is provided. Then, a detailed discussion of the factors influencing the upconversion‐assisted photopolymerization comprising UCP nature and characteristics, UCP content, presence of fillers/pigments/additives, laser intensity, photoinitiator content, and maximum absorption wavelength of photoinitiator is provided, and recent progress in improving these factors is presented. Finally, the advantages and drawbacks of the UC‐initiated polymerization are discussed, and perspectives for future directions are suggested.Highlights NIR‐induced upconversion‐assisted photopolymerization garners growing interest. Influential factors in upconversion‐assisted photopolymerization are thoroughly discussed. The recent progress on improving these factors and the future directions are provided.

Comparison of continuous technologies for vegetable oils epoxidation

Epoxidized Vegetable Oils (EVOs) are an important class of chemical compounds obtained from biomass and used as intermediates to produce several bio-products and chemicals, such as hydroxy-alkoxy compounds, diols, amines, and carbonates. Epoxides originating from vegetable oils and their derivatives, namely fatty acids or alkyl esters, are still produced by semibatch technology which suffers from severe mass transfer limitations and long reaction times, thus impairing the final product selectivity and restraining the overall productivity. In this work, two continuous reactor technologies to produce epoxides from vegetable oils were developed and compared. The first configuration, consisting of only one jacketed tubular reactor operated in co-current up-flow mode, showed a good performance at T = 318 K achieving a double bond conversion exceeding 95 % and an epoxide selectivity higher than 90 %. The second technology, where two jacketed tubular reactors connected in series were operated in up-flow mode, gave comparable conversions and selectivity to the previous one, but under somewhat milder conditions, at T = 294 K and 298 K for the first and second reactor, respectively, and in the absence of any added acid catalyst. Following this latter concept, additional experiments were performed in the presence of different vegetable oils as starting materials to confirm the performance with more common feedstocks. Both configurations showed results that clearly exceed the performance of the current semibatch process.

MIL-101(Cr) entrapped polyol-synthesized iron promoted platinum bimetallic nanoparticles system for synergistic selective hydrogenation of cinnamaldehyde

The interfacial characteristics of platinum (Pt) metal catalysts can be systematically regulated by interacting them with electropositive metals, leading to synergistic interactions for extensive catalytic applications. In this study, an evenly dispersed polyol-synthesized iron (Fe)-promoted Pt bimetallic nanoparticle (BNPs) system was embedded in MIL-101(Cr). The PtFe2@MIL-101(Cr) catalyst unveiled remarkable activity (86%) and selectivity (89%) for the superior hydrogenation of the targeted CO bond of cinnamaldehyde (CAL). The exceptional hydrogenation performance can be credited to the interplay of the geometric and electronic properties arising from charge shuttling between Fe and Pt within the homogenously distributed Pt–Fe bimetallic nanoparticle system. The experimental results indicate enhanced valence electrons in the Pt d-band through the mutual synergetic interface between the Pt and Fe BNPs. Consequently, these Fe–Pt sites functioned as interfacial electrophilic and nucleophilic (Lewis acid-base) sites, enhancing H2 activation and facilitating CO bond conversion to yield unsaturated cinnamal alcohols (COL). Additionally, the narrow pores of MIL-101(Cr) encapsulating the Pt–Fe BNPs induced steric hindrance, allowing only CO bond hydrogenation. Furthermore, the PtFe2@MIL-101(Cr) catalyst maintained its optimal hydrogenation performance over five cycles, demonstrating no substantial loss in either CAL conversion or COL yield, thus endorsing the universal practical applicability of the catalyst.

Thermal Weathering of 3D-Printed Lunar Regolith Simulant Composites.

The production of lunar regolith composites is a promising venture, especially when enabled by extrusion-based additive manufacturing techniques such as direct ink write. However, both three-dimensional (3D) printing production and usage of polymer composites containing regolish on the lunar surface are challenges due to harsh environmental conditions such as severe thermal cycling. While thermal degradation in polymer composites under thermal cycling has been studied, there is limited understanding of how polymer properties impact the mechanical performance of lunar regolith composites when both printing and usage are carried out under extreme thermal conditions. Here, we aim to bridge that gap through the creation of composites containing a lunar Highlands regolith simulant suspended in an ultraviolet (UV) curable binder, which were printed at -30 °C and thermally cycled between weekly lunar day (127 °C) and weekly night (-190 °C) temperatures. We validate that thermal stresses cause both physical and chemical degradation since the regolith simulant composites become stiffer, more porous, and show yellowing after exposure to thermal cycling. Moreover, we indicate that chemical degradation mechanisms seem to compete with residual polymerization in certain formulations. We attribute this phenomenon to partial crystallization of monomer species during printing at -30 °C, resulting in low vinyl bond conversion during initial curing. The results presented here shed light on the intricate interplay between thermal stresses, uncured polymer properties, and degradation mechanisms, which can help guide future use cases of regolith composites for lunar infrastructure needs.

Effect of Stearyl Methacrylate Comonomer on the Mechanical and Physical Properties of Dimethacrylate-Based Dental Resins.

This study evaluated the effect of stearyl methacrylate addition on the physical and mechanical properties of bisphenol A glycidyl methacrylate- and triethylene glycol dimethacrylate-based polymers, which are traditionally used in dental applications. Methacrylate-based monomer compositions are polymerized under the visible blue light spectrum. An analysis of double bond conversion, surface microhardness test, three-point bending test and water sorption and water solubility were tested to determine the physical and mechanical properties of the dental polymers. The results indicated that stearyl methacrylate addition up to 25 wt% reduced the water sorption of the polymers. At amounts of stearyl methacrylate higher than 25 wt%, the solubility of the polymer in water increases due to the monofunctional structure. Mechanical properties are negatively affected by the increasing stearyl methacrylate ratio. Further, the addition of stearyl methacrylate slightly increased thermal stability. As such, the amount of stearyl methacrylate in a polymer composition is critical for the optimization of its mechanical and physical properties. According to the results, the amount of stearyl methacrylate has to be between 12.5-25 wt%.

Surface modification strategies for improved cellulose nanocrystal integration in 3D-Printed bio-based acrylate matrix

The current application of renewable resources in vat photopolymerization (VP) 3D printing is rather limited, emphasizing the importance of incorporating bio-based materials into additive manufacturing (AM). In this study, VP 3D printing technology was applied to create composites (derived from soybean oil-based resin) reinforced with cellulose nanocrystals (CNC). Two distinct modifications for CNC, i.e., the acrylation and functionalization with methyl methacrylate, were selected to achieve strong bonding with the UV-curable acrylate matrix. With the use of 0.1 wt% of modified CNC, the resins retain remarkable performance and support the creation of high-resolution prints. The successful integration of modified CNC showed significant improvements in tensile and flexural properties, e.g., elongation at break increased by 75 % and 295 %, respectively. The addition of modified CNC fillers also increased tensile strength by 147 % and flexural strength by 121 %. Fourier-transformation infrared (FTIR) spectroscopy and dynamic mechanical analysis (DMA) testified to the enhanced interface between filler and matrix. The morphological features and print quality were examined with microscopic analysis, UV-VIS spectroscopy, and colorimetry. The resin showed exceptional printing resolution, characteristic of VP printing, and yielded double bond conversion rates greater than 70 %. The findings presented here indicate that the addition of 0.1 wt% of modified CNC to bio-based resins results in an exceptional increase in the mechanical performance and dimensional stability of printed materials.

A dual-functional α-diketone-based disulfide monomer for visible LED photopolymerization: Mitigating volumetric shrinkage and triggering polymerization

A α-diketone-based disulfide monomer (OHS), which serves the function of both volumetric shrinkage decreases and photopolymerization initiation under the irradiation of 405 light-emitting diode (LED) was designed and synthesized. The photochemical and photoinitiating performances were study by ultraviolet–visible spectrophotometer, electron spin resonance spin trapping (ESR-ST) experiments and real-time infrared spectrometer (FTIR). Despite OHS exhibits weak absorption at approximately 405 nm, OHS can effectively produce aromatic sulfur radicals to induce photopolymerization of itself and the bisphenol A glycerolate dimethacrylate (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) photopolymerizable system under 405 nm LED exposure. With increasing OHS addition, the final double bond conversion and maximum polymerization rate of the Bis-GMA/TEGDMA system improved, reaching up to 86.0% and 2.33% s-1, respectively. Importantly, OHS significantly reduces the volumetric shrinkage ratio of the Bis-GMA/TEGDMA photopolymerizable system, with the volumetric shrinkage ratio (5.01%) of the system containing 5% OHS declining by almost 50% compared to that (8.51%) of the control system without OHS. This reduction is attributed to reversible characteristic of the disulphide bonds and intermolecular hydrogen bondings. Furthermore, OHS has little influence on the gelation ratio, thermostability, and frictional resistance of the cured film.

A UV-curable silicone acrylate anti-smudge coating containing tertiary amines and Ti with the ability to prevent oxygen inhibition

UV curing technology has numerous advantages such as a fast curing speed, environmental friendliness, energy conservation, and thus it is widely used in industrial production and out daily life. Free-radical polymerization is the primary mechanism for UV curing technology. However, free-radical polymerization is susceptible to oxygen inhibition, which leads to incomplete curing when this approach is employed in the air. This paper describes a new silicone acrylate prepolymer, four double bonds and a tertiary amine group at each end of the prepolymers can effectively solve the oxygen inhibition. We synthesized an alkoxymethacryloxy titanium monomer (Ti-MA). This monomer was mixed with the prepolymer and UV cured, which resulted in improved coating properties. The results showed that the double bond conversion of the prepolymer reached 90.66 ± 0.5 % at 20 s, and the residual adhesion rate also exceeded 90 %. The hardness of the coating could reach pencil hardness level 4H with the addition of Ti-MA, and the water contact angle reached 104.5 ± 0.2°, as well as excellent anti-smudge and anti-fingerprint properties. This study provides a new method to solve the oxygen inhibition problem, which has a broad application prospect in the field of coatings.

Photopolymerization initiated by p-diethylene glycol monomethyl ether cinnamyl formamide-based disulfide under 455 nm LED with minimized volume shrinkage

This study introduces a novel p-diethylene glycol monomethyl ether cinnamyl formamide-based disulfide monomer, N,N′-(disulfanediylbis(2,1-phenylene)) bis(4-(4-(2-(2-methoxyethoxy)ethoxy) phenyl)-2-oxobut-3-enamide) (Mp-BSCF), designed to reduce the volume shrinkage of photosensitive resins and initiate monomer polymerization under 455 nm LED light irradiation. The photochemical properties and photoinitiation efficiency of Mp-BSCF are systematically investigated using UV–vis absorption spectroscopy, electron paramagnetic resonance (EPR) and real-time infrared spectroscopy. Although its weak absorption around 455 nm, Mp-BSCF can generate arylthiyl radicals under 455 nm LED irradiation, and then effectively initiate the polymerization of triethylene glycol dimethacrylate (TEGDMA)/A glycerolate dimethacrylate (Bis-GMA) system. Increasing Mp-BSCF addition enhances the final double bond conversion and maximum polymerization rate of the TEGDMA/Bis-GMA system, reaching up to 82.0 % and 2.02 % s−1, respectively. Notably, Mp-BSCF significantly reduces the volume shrinkage of the photopolymerization system, with the addition of 10 % Mp-BSCF resulting in a 50 % reduction compared to the control system. This reduction is attributed to the dynamic reversible nature of the SS bond “breaking-recovery” and the intermolecular hydrogen bond interaction. Additionally, Mp-BSCF improves the thermal stability, friction resistance, and hardness of the TEGDMA/Bis-GMA photopolymerization system.

Capsanthin-iodonium salt system for free radical photopolymerization under LED irradiation

The current photoinitiator (PI) is effective under mercury lamps but exhibits limited selectivity towards different radiation sources, which hinders its compatibility with eco-friendly LED lighting and raises concerns about toxicity and deep coloration. Capsanthin (Cap), with its strong photo-absorption in the 400–500 nm range, utilizes its conjugated structure to align the PI's absorption wavelength with the LED's emission spectrum. This study introduced Cap as a natural photosensitizer (PS) for free radical photopolymerization under LED irradiation. The Cap-based initiation system demonstrated promising photoinitiating capabilities under a 405 nm LED, achieving over 50 % double bond conversion in polymerized monomers. Furthermore, the system's photobleaching properties were exceptional, and its cytotoxicity was significantly lower than that of traditional PIs, such as benzoin methyl ether. The Cap's photochemical behavior under LED irradiation was explored, investigating its photoinitiating capacity and mechanism through fluorescence, photolysis, and electron paramagnetic resonance techniques. This research is vital for developing bio-based photoinitiating systems for photopolymerization in LED light environments.

Novel lignin α-O-4 derived hydrogen donors in CQ-based photoinitiating systems for dental resins

The purpose of this work is to explore the properties of the lignin-derived amine-free photoinitiating systems (PISs) during the curing process. Four novel hydrogen donors (HD1, HD2, HD3, and HD4) derived from lignin α-O-4 structural were designed and synthesized by simple methods, and their low C–H bond dissociation energies on methylene were determined by molecular orbitals theory. Four experimental groups using CQ (camphorquinone)/HD PIs formulated with Bis-GMA/TEGDMA (70 w%/30 w%) were compared to CQ/EDB (ethyl 4-dimethylamino benzoate) system. The photopolymerization profiles and double bond conversion rate was tracked by FTIR experiments; the color bleaching ability of the samples and color aging test assay were performed using color indexes measurements; The cytotoxicity of the samples was also compared to EDB related systems. All of the experimental groups with new HDs were compared to the control group with EDB by statistical analysis. Compared to CQ/EDB system, new lignin-derived hydrogen donors combined with CQ showed comparable or even better performances in polymerization initiation to form resin samples, under a blue dental LED in air. Excellent color bleaching property was observed with the new HDs. Aging tests and cytotoxicity examination of the resin were performed, indicating the new lignin compounds to be efficient hydrogen donors for amine-free CQ-based photo-initiating system. Novel lignin α-O-4 derived hydrogen donors are promising for further usage in light-curing materials.

Comparing Properties of Urethane Dimethacrylate (UDMA) Based 3D Printing Resin Using N-Acryloylmorpholine (ACMO) and Triethylene Glycol Dimethacrylate (TEGDMA) Separately as Diluents

The purpose of our study reported here was to investigate the performance of urethane dimethacrylate (UDMA) based 3D printable resin systems when using N-acryloylmorpholine (ACMO) as a diluent. UDMA was mixed with ACMO with a series of mass ratios, and the viscosity, degree of double bond conversion (DC), volumetric shrinkage (VS), flexural strength (FS), and modulus (FM), water sorption (WS) and solubility (SL), hardness, wear resistance, and accuracy thereof the obtained resin systems were studied and compared with triethylene glycol dimethacrylate (TEGDMA) diluted resin systems. The results showed that the ACMO diluted resin systems had a higher viscosity than the TEGDMA diluted resin systems with the same diluent concertation. Replacing TEGDMA with ACMO showed improvement in DC, VS, FS and FM in dry conditions, and the accuracy of 3D printable resin systems. However, the reduction of water resistance and wear resistance would limit the application as dental restoration materials of ACMO diluted 3D printable resin systems. With the aim to improve the water resistance and wear resistance of ACMO diluted 3D printable resin systems, we suggest further research concerned about using a new base resin and optimizing resin composition should be undertaken.

Efficient Preparation of Poly(allyl diglycol carbonate) (PADC) Nuclear Track Detectors: UV Photopolymerization.

The decay of radon gas in soil and buildings produces alpha radiation, which is the second leading cause of lung cancer in humans. Therefore, by conveniently detecting radon gas in the environment, potential sources of danger can be identified early, and necessary measures can be taken to protect human health. Solid-state nuclear track detectors prepared from polyallyl diglycol carbonate (PADC) resin are the most sensitive detectors for alpha radiation released by radon gas. The traditional method of preparing PADC resin involves free radical thermal polymerization, which suffers from issues such as low polymerization efficiency, long processing time, and the occurrence of defects in the product. In this study, PADC resin was efficiently prepared using a UV initiator. Starting from the polymerization mechanism, experiments were designed using a controlled variable approach, and a rational polymerization apparatus was devised. By comparing the double bond conversion rate, transparency, hardness, and yellowness index of the polymers, the optimal initiator for PADC resin, 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173), was selected. The influence of irradiation intensity, irradiation time, and UV initiator dosage was investigated. The performance of the polymers, including double bond conversion rate, optical properties, dynamic mechanical properties, etching rate, and track detection efficiency, was analyzed. The experimental conditions for preparing PADC resin were optimized: irradiation intensity of 12 mW/cm2, irradiation time of 25 min, and UV initiator dosage of 5 parts. The resulting resin polymer had a double bond conversion rate of 93.2% and a track detection efficiency of 0.714.

Mechanism and kinetics study of vanadium leaching from landfilled metallurgical residues by ultrasonic with ozonation enhancement in a low-acid medium

Landfilled metallurgical residues are valuable raw materials for the recovery of strategic vanadium resources. However, efficient separation of vanadium from these residues is challenging due to its strong oxidation resistance and coating within silicate inclusions. To address this issue, this study proposes an enhanced leaching process utilizing the synergistic effect of O3-catalyzed ultrasonic field in a low concentration sulfuric acid system. Results show that following a 10-minute O3 and ultrasonic treatment, the direct leaching rate of vanadium experienced a remarkable 46.7 % increase. Quenching experiments revealed a hierarchical order of active species within the reaction process:⋅OH >⋅O2−> H+, with⋅OH oxidation exhibiting the most pronounced capacity for disrupting the inclusion structure. Electron Paramagnetic Resonance analysis indicated that the highest⋅OH yield arose from the combined application of ultrasound and ozone. Kinetic investigations demonstrated that the vanadium leaching process is governed by interfacial chemical reactions. The activation energy of vanadium oxidation leaching under ultrasonic-O3 conditions was determined to be 40.41 kJ/mol, representing a 20.19 % reduction compared to ultrasonic conditions alone. Through the integration of analysis, characterization, and comparative evaluations, it was discerned that the synergistic impact of ultrasonic and ozone treatments significantly enhances the breakdown of silicate inclusions by low-concentration HF, particularly in the conversion of SiOSi bonds into SiOH bonds and SiF bonds. In summary, the refined leaching methodology incorporating ozone catalysis in conjunction with ultrasonic treatment provides a new idea for the separation and extraction of refractory residual vanadium.

New type of UV cured low dielectric naphthalene resin: Structure-activity relationship of different substitution sites

UV-curing low dielectric materials exhibit wide applications in the field of additive manufacturing of electronic packaging, owing to their environmental protection, good thermal stability, low dielectric constant (Dk), and dielectric loss (Df). Wherein, one-step UV curing realizes process simplification of low dielectric materials gradually sparked widespread research. In this work, a series of novel naphthalene-based low dielectric materials were prepared for one-step UV curing. The double bond conversion rate of resins exceeds 90 % in a short time and the resins perform exceptional dielectric properties (Dk < 2.8, Df < 0.009, 110 MHz), high thermal stability (T5% > 270 °C), and hydrophobicity (water contact angle > 95°). Notably, 1,6-naphthalene dimethacrylate/Trihydroxymethylbutyl trimethylacrylate (1,6-NEA/TMPTA) suggests lowest dielectric performance (Dk = 2.19, Df = 0.005) with significant thermal stability (Tg = 190 °C, T5% = 367.4 °C) because the π-π conjugation of the asymmetric structure of 1,6-NEA, which allows for a greater variety of stacking patterns and increases the effective collisions between the reactive sites of the photosensitive monomer and the reactive diluent. This work has revealed the structure-activity relationship between the substituents on naphthalene derivatives and their photochemical properties, providing a novel methodology for the development of low dielectric electronic packaging materials through additive manufacturing techniques.