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Advancements in nanotechnology allow for the development of in situ or ex situ prepared nanocoatings and nanoparticles which are valuable in the electronics industry due to their intrinsic physical and chemical properties. Printed electronics, intended for applications such as flexible displays and smart labels, offer a distinct advantage over conventional products. The primary components used in printed electronics are the nano‐ink containing polymer matrix and the substrate for printing. Gold, silver, and copper are commonly chosen for these processes because of their excellent electrical conductivity. In the electronics industry, it is well‐known that producing conductive ink typically requires high temperatures and extended processing times, as is the case with conventional methods. In this study, in situ prepared silver nanoparticles (AgNPs) in a crosslinked polymeric matrix are achieved simultaneously using environmentally friendly polyvinyl alcohol (PVA) and acrylamide via photopolymerization. The generated radicals facilitated the formation of silver nano particles while simultaneously forming a cross‐linked network that underwent further processing to transform into ink. The obtained polymer ink formulation is suitable for use with a refillable pen, and it is determined that it dries shortly after writing on surfaces such as paper and glass and exhibits high durability under room conditions. [ABSTRACT FROM AUTHOR]

Controlling the precision and mechanical cohesion of 3D-printed parts remains a central concern in the development of additive manufacturing. A two-dimensional finite element model of the photopolymerization of a complex sensitive resin, formulated with three monomers to better represent commercial resins, in a stereolithography apparatus is proposed as a tool for predicting and optimizing formulation of photosensitive resin and its printing parameters. By considering light illumination, chemical reaction, and heat transfer in a resin exposed to a moving ultraviolet (UV) laser source, this first approach accounts for monomer-to-polymer conversion and polymerization rate in agreement with experimental results obtained by Fourier-transform infrared spectroscopy (FT-IR) monitoring and the use of semi-empirical models. The temperature gradient along the exposed photosensitive material was also estimated. By varying the photoinitiator content and simulating the addition of an absorbing filler via the molar extinction coefficient, it was shown that a higher photoinitiator concentration and the presence of strongly absorbing fillers lead to a reduction in the light penetration depth, which can result in structural defects without adaptation of the layer thickness to be printed. [ABSTRACT FROM AUTHOR]

In the vat photopolymerization (VPP) 3D printing of ceramic cores, the solid loading is generally conducive to the microstructure and performance of products, owing to the improved bonding between adjacent layers and enhanced dimensional accuracy with increasing solid loading. In this work, the content of ceramic powder in photosensitive resin was optimized, the solid loading increased from 56 vol% to 68 vol%, and a novel curing model was established to explain the impact of solid loading on the printing precision. During sintering, the shrinkage is regulated to approximately 3 %, demonstrating a more homogeneous structure. The interlayer strength increased to 11.43 MPa while maintaining an apparent porosity of 23.47 %. Furthermore, the anisotropy of VPP-3D printed ceramic cores dependent on the solid loading was investigated. The ratio of vertical strength to horizontal strength (σ V /σ H) increased from 0.57 to 0.68 when the solid loading grew from 56 vol% to 68 vol%. At 1540 °C, the value of σ V /σ H was further enhanced to 0.81. This value met the precision casting criteria for ceramic cores effectively. This work can provide a reference for the investigation of high-solid-loading ceramic cores. [ABSTRACT FROM AUTHOR]

Silica particles were dispersed in 11 acrylic monomers at various concentrations. The dispersibility of the silica particles was evaluated based on the viscosity of the slurry. Furthermore, the relationship between the viscosity of the slurry and the solubility parameters (SPs) of the silica particles and acrylic monomers was investigated. When the SPs of the silica particles and acrylic monomers were close, the viscosity of the silica slurry decreased and high concentrations of the silica particles could be dispersed in the acrylic monomers. Therefore, SP can be used for predicting the dispersibility of silica particles. The prepared slurry was then used to fabricate sintered silica glass. Silica slurry was cured through photopolymerization to obtain a green body, which was then heat-treated at 850 °C in air atmosphere and sintered at 1710 °C under vacuum to obtain sintered silica glass. Transparent sintered silica glass with no cracks was obtained using 4-hydroxybutyl acrylate, which has a similar SP to that of silica particles, as a solvent. The obtained sintered silica glass exhibited a transmittance of 92 % at a wavelength of 400 nm. In the ultraviolet region, light absorption originated from two-coordinated Si in the glass. The absorption spectrum in the infrared region showed an extremely low peak of the SiOH group, indicating that low-OH silica glass was obtained. Thus, this study provides a new method for fabricating silica glass and provides a method of selecting solvents for the slurries used in powder sintering. [ABSTRACT FROM AUTHOR]

The triplet excited state lifetime of a photosensitizer is an essential parameter for diffusion‐controlled energy‐ and electron‐transfer, which occurs usually in a competitive manner to the intrinsic decay of a triplet excited state. Here we show the decisive role of luminescence lifetime in the triplet excited state reactivity toward energy‐ and electron transfer. Anchoring two phenyl anthracene chromophores to a ruthenium(II) polypyridyl complex (RuII ref) leads to a RuII triad with a luminescence lifetime above 100 μs, which is more than 40 times longer than that of the prototypical complex. The obtained RuII triad sensitizes energy transfer to anthracene‐based annihilators more efficiently than RuII ref and enables red‐to‐blue photon upconversion with a pseudo anti‐Stokes shift of 0.94 eV and a moderate upconversion efficiency near 1 % in aerated solution. Particularly, RuII triad allows rapid photoredox catalytic polymerizations of acrylate and acrylamide monomers under aerobic condition with red light, which are kinetically hindered for RuII ref. Our work shows that excited state lifetime of a photosensitizer governs the dynamics of the excited state reactions, which seems an overlooked but important aspect for photochemistry. [ABSTRACT FROM AUTHOR]

Precise pixel control of quantum dots (QDs) offers unparalleled opportunities for various display applications, such as the OLED and Micro-LED. However, precise selective patterning of QDs is still a challenge due to the lack of a design methodology. Therefore, the aim of this study was thus to develop a photoinitiator-grafted oligomer for "on demand" control of active free radicals to improve the line edge roughness in QD patterning. This photosensitive oligomer was constructed by grafting the photosensitive benzophenone structure onto a phenolic resin oligomer, thus resulting in the confinement of active free radicals and highly selective photolithography. As a proof of concept, we have demonstrated high-quality QD patterns with high resolution and low edge roughness by using direct in situ photolithography. This work opens an avenue for the precise design and synthesis of QD photoresists, improving the precision of QD patterning for display applications. [ABSTRACT FROM AUTHOR]

Vat photopolymerization is an additive manufacturing process for producing ceramics with high printing resolution. Extending this approach to multi-material additive manufacturing, the aim is to combine two or more different ceramics in a single component to aggregate their advantages. For this, binders for different ceramic materials are required. To enhance the debinding step, this work aimed to develop a versatile binder system suitable for different ceramic materials. Finally, a binder system was developed and qualified for several different ceramic materials. By thermogravimetrical analyses, a suitable temperature curve for debinding was derived. In a final sintering step, the components were densified almost defect-free. Therefore, this work serves as an enabler for multi-material vat photopolymerization. [ABSTRACT FROM AUTHOR]

Billions of patients struggle with dental diseases every year. These mainly comprise caries and related diseases. This results in an extremely high demand for innovative, polymer composite filling materials that meet a number of dental requirements. The aim of the study was to modify the light-cured composition of permanent dental fillings by changing the composition of the liquid organic matrix. New photoinitiators (DQ1-DQ5) based on a quinoline or quinoxaline skeleton and a co-initiator-(phenylthio)acetic acid (PhTAA) were used. In addition, monomers that have been traditionally used in dental materials were replaced by trimethylolpropane triacrylate (TMPTA). The neutral dental glass IDG functioned as an inorganic filler. The influence of the storage conditions of the developed composites in solutions simulating the natural oral environment during the consumption of different meals on sorption, solubility, and mass changes was assessed. For the tests, fifty-four cylindrical composite samples were prepared according to ISO 4049 guidelines and stored in different solutions. Distilled water, artificial saliva, heptane, 10% ethanol, and 3% acetic acid, as well as solutions containing pigments such as coffee, tea, red wine, and Coca-Cola, were used for the studies. The samples were stored in these solutions for 7, 14, 28, 35, 42, 49, 56, and 63 days at 37 °C. The sorption, solubility, and mass changes in the tested samples were determined, and the trend of these changes as a function of storage time was presented. The results were analyzed considering the nature of the solution used, i.e., aqueous, hydrophobic, and acidic. The properties evaluated changed in a different way, characteristic for each of the abovementioned solution groups. It was found that the type of solution simulating the natural environment of the oral cavity has the greatest influence on the sorption, solubility, and changes in the mass of the tested material. [ABSTRACT FROM AUTHOR]

Two coumarinacyl bromides, 3‐(bromoacetyl)coumarin (BAC) and 3‐(bromoacetyl)‐7‐methoxycoumarin (BACO), were developed for the photopolymerization of N‐ethylcarbazole to construct conjugated polymer under visible and near‐infrared light irradiation. BAC outperformed the conventional phenacyl bromide photoinitiator, exhibiting superior photoinitiation performance due to its optimal absorption characteristics and electron transfer efficiency. The obtained poly(N‐ethylcarbazole) was thoroughly characterized, demonstrating the successful synthesis of a conjugated polymer with desired properties. Dedoping led to improved optical properties and film morphology. The polymerization mechanism was elucidated using transient absorption spectroscopy, revealing efficient electron transfer from the excited photoinitiators to N‐ethylcarbazole. [ABSTRACT FROM AUTHOR]

The preparation of Si 3 N 4 ceramics by vat photopolymerization (VPP) has motivated increasing research interest. However, it is challenging to prepare Si 3 N 4 ceramics by VPP due to the high UV-light absorbance and refractive index of powder. In this paper, a method for Al 2 O 3 -coated Si 3 N 4 powder was proposed. Combined with the boehmite-coated and high-temperature treatment, Al 2 O 3 was successfully coated on the surface of Si 3 N 4 powder. The effect of Al 2 O 3 content on the properties of Si 3 N 4 powders, slurry and the sintered Si 3 N 4 samples were investigated. The Al 2 O 3 coating layer not only improves the curing forming ability of Si 3 N 4 slurries, but also can directly act as one of the sintering aids of Si 3 N 4 ceramics. The bulk density of the samples decreases from 3.04 ± 0.02 g/cm3 to 2.97 ± 0.01 g/cm3 with the increase of coating content, while the porosity increases from 5.38 ± 0.89 % to 7.54 ± 0.63 %. The sample of 5 wt % Al 2 O 3 coating content has the maximum flexural strength of 474.28 ± 16.38 MPa and the highest relative density of 94.62 ± 0.89 %. This work can not only obtain a great modification effect, but also promote the dense sintering of Si 3 N 4 ceramics during subsequent stages, which provides a constructive method for modifying Si 3 N 4 powders to achieve photopolymerization. [ABSTRACT FROM AUTHOR]

Porous Si 3 N 4 ceramics are widely applied in aerospace and mechanical fields owing to their excellent properties. Furthermore, vat photopolymerization (VPP) technology can fabricate Si 3 N 4 components with complicated structures and high precision, but its layer-by-layer printing method leads to poor mechanical properties of ceramics. In this study, porous Si 3 N 4 ceramics with a porosity of 28.41 % strengthened by directional β-Si 3 N 4 were fabricated by combining VPP technology and seeding method. Rheological behavior and curing properties of the slurry were explored, and the influence of β-Si 3 N 4 content on the mechanical properties of printed Si 3 N 4 ceramics was investigated systematically. With the increase of β-Si 3 N 4 content, the orientation degree of β-Si 3 N 4 grains increased gradually, while fracture toughness and flexural strength of the ceramics exhibited a trend of increased first and then decreased and Vickers hardness gradually decreased. As β-Si 3 N 4 content increased to 5 wt%, the fracture toughness and flexural strength of porous Si 3 N 4 ceramics were improved from 4.23 MPa m1/2 and 214.7 MPa–5.65 MPa m1/2 and 272.0 MPa, respectively. Therefore, this work indicates that vat photopolymerization combined with seeding method is a promising approach for the fabrication of porous Si 3 N 4 ceramics with high performance and complex structures. [ABSTRACT FROM AUTHOR]

Interventional embolotherapy is widely used in clinical treatment of conservative liver cancer. This method has many advantages, such as good targeting, mild trauma, and low complications. The operation of transcatheter arterial embolization is to inject embolic microspheres into the arterial blood vessels of diseased organs, so as to occlude them and interrupt the blood supply, thus achieving the therapeutic purpose. However, there are still some deficiencies in clinical materials, for example catheter obstruction or vascular regeneration. In this study, pentaerythritol triallyl ether (APE) and its esterified product APEAA were used to prepare new polymeric amorphous embolic granules (PAPE and PAPEAA). The purpose is to overcome the excessive swelling problems of traditional polyvinyl alcohol granules (PVA). We verified that PAPE and PAPEAA were quickly and efficiently polymerized by photo‐driven radical‐mediated [3 + 2] cyclopolymerization mechanism (PRMC). RT‐FTIR was used to explore the best route of photopolymerization initiated by four photoinitiators. Four physical properties experiments all prove that the particle has good physical properties. In vivo animal experiments, it is confirmed that the particles can achieve the expected effect and have good biological safety. The results show that the amorphous granules can meet the requirements of clinical injection and can be used as a new embolic material. [ABSTRACT FROM AUTHOR]

Sustainability in additive manufacturing (AM) (3D printing) could play a pivotal role for manufacturers and producers in the next‐generation manufacturing framework. The market for 3D printing is expanding rapidly, and it is expected to do so in the foreseeable years to come. As ecologically, responsible manufacturing gains more attention, renewable substitutes for regular commercial 3D printable inks must be developed for lower environmental carbon footprints (less CO2 emissions, recycling, bio‐compatibility, and zero waste). Herein, we review the recent literature on using vegetable oil (VO) as bio‐based inks for sustainable formulations for digital light processing or stereolithography additive printing. The feedstock selections (VO, terpenes, and waste cooking oil), and the chemistry of the VO‐based synthons toward sustainability in the field of photopolymerization‐based 3D printing are discussed. These renewable materials can mitigate the detrimental environmental effects of AM while remaining competitive with the existing fossil‐based resins produced by industrial manufacturers. The current challenges and limitations of AM in terms of surface finish, material properties, photo‐curing time, and end‐of‐use recycling options from biomass‐derived photocurable monomers are also identified. Overall, this development promotes the bio‐based economy and allows for the on‐demand production of a variety of sustainable inks for AM and sustainable end‐of‐use products. Highlights: The significance of vegetable oils (VOs) as photopolymerizable monomers is explored.The necessity for 3D printing, specifically recycling and end‐of‐use, for the industrial revolution is provided.Green developments in stereolithography/digital light processing 3D printing utilizing VOs are covered. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) of polymers is a highly versatile technology that can be applied to many independent sectors like automotive, aviation, medicine, and dentistry. Since it has great potential for rapid prototyping, clean‐process concepts, and the ability to produce complex shapes, the layer‐by‐layer printing method is one of the most promising alternatives for future industrial production efforts. In that sense, different from the previous studies, this work aims to elucidate the friction and wear properties of the special dental samples manufactured via photopolymerization‐based AM technology according to both for printing parameters, and dry sliding test variables. Also, this is the first initiation to examine the combined influences of the UV exposure time, building direction, and sliding force on the surface roughness, hardness, friction coefficient, wear rate, and main plastic damage mechanism of the printed samples. The results showed that the maximum average hardness value was detected as 89.8 Shore D for vertically built samples printed with 8 s exposure time. In addition, vertically printed samples exhibited better wear resistance than the horizontal samples and the rising exposure time generally affected affirmatively the hardness levels of the samples. The lowest volume loss of 78 mm3 belonged to the vertical sample at 5 N. Further, increasing test force levels caused a decrease in the friction coefficient results and triggered the volume loss increase in the samples. Among all samples, the calculated friction coefficient values changed between 0.3 and 0.87. On the other side, scanning electron microscopy (SEM), and energy‐dispersive spectroscopy (EDS) analyses pointed out that ascending exposure times led to the altering contact surface matchings determining the final volume loss outcomes. Highlights: To obtain better surface quality, vertical printing was a useful option.Horizontally printed samples exhibited higher friction coefficients.Curing time positively impacted the wear resistance for both orientations.Grooves and debris parts were observed on surfaces with low exposure times. [ABSTRACT FROM AUTHOR]

The design and development of photoinitiating systems applicable to visible light delivered from light‐emitting diodes (LEDs) have attracted increasing attention owing to the wide application of photopolymerization. In this study, four aryl glycine derivatives are designed and synthesized, and their applicability as visible light‐sensitive photoinitiators is thoroughly investigated. Specifically, the photoinitiation mechanism of these aryl glycine derivatives, when combined with iodonium salt, is investigated using steady‐state photolysis, fluorescence, and electron paramagnetic resonance spin trapping techniques. It is revealed that radicals can be generated from aryl glycine derivatives/iodonium salt combinations upon exposure to blue LEDs (410 and 445 nm) to induce free radical photopolymerization (FRP) of (meth)acrylates. Additionally, besides FRP, a photobase generator based on one of the investigated aryl glycine derivatives is synthesized and demonstrates the capability to initiate epoxy‐thiol polymerization under light irradiation. The remarkable photolatent characteristics demonstrate the significant potential in broadening the application of aryl glycine derivatives in controlled photopolymerization processes. [ABSTRACT FROM AUTHOR]

A dynamic model is proposed to account for shrinkage and swelling during the photopolymerization of 1,6‐hexanediol diacrylate (HDDA) with the bifunctional initiator bis‐acylphosphine oxide (BAPO) in the presence of oxygen. The model is composed of 14 partial differential equations (PDEs) that are used to track changes in film thickness along with time‐ and spatially‐varying concentrations of monomer, initiator, oxygen, pendant vinyl groups, and seven types of radicals. Shrinkage has a noticeable influence on the model predictions. For a variety of simulated photopolymerization experiments, there is ≈9% discrepancy between predicted overall vinyl‐group conversions obtained from the current model with shrinkage and a previous model without. Prediction discrepancies become larger for simulated experiments involving thin films (8 µm) or low light intensities (1200 W m−2). In the future, it will be important to re‐estimate the kinetic parameters used in the shrinkage model to obtain accurate model predictions for use in process improvement studies. [ABSTRACT FROM AUTHOR]

Bottlebrush polymers have a variety of useful properties including a high entanglement molecular weight, low Young's modulus, and rapid kinetics for self‐assembly. However, the translation of bottlebrushes to real‐world applications is limited by complex, multi‐step synthetic pathways and polymerization reactions that rely on air‐sensitive catalysts. Additionally, most bottlebrushes are non‐degradable. Herein, we report an inexpensive, versatile, and simple approach to synthesize degradable bottlebrush polymers under mild reaction conditions. Our approach relies on the "grafting‐through" polymerization of α‐lipoic acid (LA)‐functionalized macromonomers. These macromonomers can be polymerized under mild, catalyst‐free conditions, and due to reversibility of the disulfide bond in LA, the resulting bottlebrush polymers can be depolymerized by cleaving disulfide backbone bonds. Bottlebrushes with various side‐chain chemistries can be prepared through the atom transfer radical polymerization (ATRP) of LA‐functionalized macromonomers, and the backbone length is governed by the macromonomer molecular weight and solvent polarity. We also demonstrate that LA‐functionalized macromonomers can be copolymerized with acrylates to form degradable bottlebrush networks. This work demonstrates the preparation of degradable bottlebrush polymers with a variety of side‐chain chemistries and provides insight into the light‐mediated grafting‐through polymerization of dithiolane‐functionalized macromonomers. [ABSTRACT FROM AUTHOR]

In the field of regenerative medicine, acrylated epoxidized vegetable oils are emerging as a promising avenue of exploration. The aim of this study is to evaluate the degradability of two formulations of acrylated epoxidized soybean oil (AESO): pure AESO and AESO diluted with soybean oil (SO) for potential bioprintability applications. The comprehensive investigation of these two polymeric formulations included optimization of polymerization conditions, confirmation of cytocompatibility, and, most importantly, the study of their degradability. The results reveal that AESO, used as a biomaterial for biomedical applications, undergoes a distinctive degradation process, combining both enzymatic and oxidative degradation (AESO/SO samples lose 29.45% of their weight after 60 days). This phenomenon is the result of a complex interplay of factors, including the chemical composition and physical characteristics of the polymer, the unique tissue environment in which it is implanted, and the duration of implantation. [ABSTRACT FROM AUTHOR]

In the present study, we focused on the development and characterization of formulations that function as biological inks. These inks were doped with coumarin derivatives to act as molecular luminescent sensors that allow the monitoring of the kinetics of in situ photopolymerization in 3D (DLP) printing and bioprinting using pneumatic extrusion techniques, making it possible to study the changes in the system in real time. The efficiency of the systems was tested on compositions containing monomers: poly(ethylene glycol) diacrylates and photoinitiators: 2,4,6-trimethylbenzoyldi-phenylphosphinate and lithium phenyl-2,4,6-trimethylbenzoylphosphinate. The selected formulations were spectroscopically characterized and examined for their photopolymerization kinetics and rheological properties. This is important because of the fact that spectroscopic characterization, examination of photopolymerization kinetics, and rheological properties provide valuable insights into the behaviour of photocurable resin dedicated for 3D printing processes. The next step involved printing tests on commercially available 3D printers. In turn, printing carried out as part of the work on commercially available 3D printers further verified the effectiveness of the formulations. Moreover the formulation components and the resulting 3D objects were tested for their antiproliferative effects on the selected Chinese hamster ovary cell line, CHO-K1. [Display omitted] • Bioinks doped with luminescent sensors for in situ photopolymerization monitoring. • Applications of bioinks at DLP and pneumatic extrusion 3D printing technique. • Cytotoxicity of the sensors in the tested range has not been indicated. • Intense Vis-LED radiation (405 nm) does not have a damaging effect on cells. [ABSTRACT FROM AUTHOR]

(1) Background: This study investigates the effects of curing light intensity, exposure time, and distance on the Vickers microhardness (VMH), hardness bottom-to-top ratio (HR), and temperature rise (TR) of conventional dental resin-based composite (RBC). (2) Materials and Methods: Specimens of one conventional RBC (Tetric EvoCeram, Ivoclar Vivadent) were cured with 12 different curing protocols (CPs), created with three different light intensities (Quartz Tungsten Halogen 300 mW/cm2, LED 650 mW/cm2, LED 1100 mW/cm2), two exposure times (20 and 40 s), and two distances of curing tip (0 and 8 mm). The VMH of top (VMH-T) and bottom (VMH-B) surfaces was measured. The hardness bottom-to-top ratio (HR) was calculated from VMH-B and VMH-T. The HR below 80% was rated as inadequate polymerization. The TR at the depth of 2 mm within the RBC was measured using a K-type thermocouple. Data were analyzed using Levene's test and the multivariate analysis of variance (MANOVA). The level of significance was set at p < 0.05. (3) Results: Exposure time and distance significantly influenced VMH-B and HR. Increased distance significantly reduced VMH-B, HR, and TR. CPs 300 mW/cm2/8 mm/20 s and 650 mW/cm2/8 mm/20 s produced inadequate polymerization (HR < 80%). Prolonged exposure time produced higher values of VMH-B and HR. The TR was significantly influenced by light intensity and distance. (4) Conclusions: Suboptimal light intensity (<800 mW/cm2) can produce inadequate polymerization at the lower side of the composite layer when used from a distance. Prolonged irradiation can improve the polymerization to a certain extent. Clinicians are advised to monitor the intensity of the LCUs in order to optimize the photopolymerization process. Caution is required when polymerizing with high-intensity curing light in direct contact with the RBC with longer exposure times than recommended. [ABSTRACT FROM AUTHOR]

The emulsion photopolymerization of methyl methacrylate (MMA) using red light is reported. The synthesis of poly(methyl methacrylate) (PMMA) latexes is initiated by irradiation of a new, very efficient red‐absorbing methylene blue (MB)/sodium para‐toluenesulfinate (NapTS) system in the red region (660 nm). Visible, and especially red light penetrates the dispersed medium imposed by the emulsion process better than ultra‐violet photons (UVs). However, emulsion photopolymerizations require the development of fully water‐soluble initiating systems activable by red light, which is still hugely challenging because red photons are much less energetic, therefore generally lead to less efficient photochemical processes. The influence of the surfactant concentration and the solids content is examined over particle sizes and polymerization kinetics. The polymerizations work for solids contents between 10 and 25 wt%, with narrowly distributed particles of average sizes ranging from 40 to 65 nm. Calculations of Mie scattering support the observation that at a given wavelength the larger the particles the lower the penetration. All latexes obtained are slightly blue, which are traced to the regeneration of MB when the latexes are exposed to dioxygen. The dye regeneration enables the reactivation of the photopolymerization process. [ABSTRACT FROM AUTHOR]

The prime objective of the current investigation is to develop a methodology of hybrid additive manufacturing (HAM), which is an amalgamation of vat photopolymerization (VPP) based 3D printing and pressureless sintering, for the fabrication of Ti6Al4V parts for biomedical applications. In this study, the effect of a wide range of sintering temperatures (1200 to 1600 °C), heating rate (2 to 4 °C/min), and holding time (60 to 180 minutes) has been considered. Further, the effect of process variables on three responses, namely porosity, shrinkage, and compressive yield strength, are investigated. It is found that sintering temperature is the most significant process variable, followed by heating rate and holding time, influencing all three responses. With an increase in sintering temperature, porosity reduces while shrinkage and compressive yield strength increase. Further, fabricated specimens are characterized using XRD and EDS analysis. XRD analysis confirms the existence of both α and β-phases, and EDS analysis negates any possibility of significant contamination during sintering. Microstructure evolution from SEM micrographs suggests significant neck growth and densification, with fully connected pores, which ensures good bonding between powder particles. The present investigation's outcome helps develop porous near-net shape complex parts for biomedical applications. [ABSTRACT FROM AUTHOR]

Phenacyl bromide has been explored as a new Norrish Type I photoinitiator for radically polymerizing methyl methacrylate and styrene monomers. A straightforward radical photopolymerization method using UVA light for the synthesis of chain-end functional poly(methyl methacrylate) and polystyrene has been developed. The process has been refined for both bulk and solution photopolymerizations. Chain-end functionalization was demonstrated by the formation of block-copolymers of the bromine-ended homopolymers, utilized as macroinitiators, resulting in an increase in the molecular weight of the corresponding precursor, observed by gel permeation chromatography (GPC). Block copolymerization was initiated by radicals generated at the chain-ends by a halogen-atom transfer reagent, namely, dimanganese decacarbonyl (Mn2(CO)10). This simple light-induced method is promising for the additive manufacturing field such as vat photopolymerization, stereolithography, digital light processing as it yields chain-end functional materials that can be further processed. Table of Contents (TOC). [ABSTRACT FROM AUTHOR]

This article reports the synthesis of a novel perfluoropolyalkylether (PFPAE) vinylether monomer and its use as a comonomer in the thiol‐ene photopolymerization of a trifunctional thiol together with a trifunctional vinylether. The crosslinked copolymers are obtained in the form of few mm thick layers and characterized. By changing the thiol/ene ratio, the polymers are optimized to tailor their surface composition and obtain adhesion between two thick layers despite the presence of the fluorinated monomer. The final bilayered structures are adhesive, and appeared chemically resistant, with good dimensional stability: therefore, these fluorinated thiol–ene based copolymers are likely to be of interest for applications based on layer‐by‐layer processes, such as additive manufacturing and microfluidics. [ABSTRACT FROM AUTHOR]

Ionic skin with ionic mechanotransduction similar to human skin can perceive stimuli by ionic conduction, holding great potential in novel human‐machine interactions. However, the high‐density integration of ionic skins still faces significant challenges due to the difficulty in fabricating high‐density patterned ionogel arrays with simple manufacturing processes. Herein, the study reports a high‐density ionic skin (HI‐Skin) based on ionogel array patterned by direct microlithography. The photosensitive ionogel (PIG) is synthesized by rapid ultraviolet‐induced in situ photopolymerization process. The direct microlithography of PIG is developed, which allows to directly pattern ionogel precursors by selective exposure to ultraviolet light and development. Simple and low‐cost preparation of PIG array with the minimum line width of 200 µm is realized. Furthermore, HI‐Skin is constructed by integrating patterned PIG arrays with row and column electrodes, and the density is up to 49/cm2. The HI‐Skin demonstrates high sensitivity of 126.8 kPa−1 and low crosstalk of −8.93 dB. By integrating the HI‐Skin and a microcontroller, a multichannel signal acquisition system is built to achieve detection of multiple motion trajectories. This work opens an avenue for the simple construction of high‐density ionic skin. [ABSTRACT FROM AUTHOR]

Vat photopolymerized 3D printing technology can be used to fabricate ceramics with complex shapes. However, the extensive use of photosensitive resins as binders is not conducive to achieving crack-free ceramic green parts, especially the Si 3 N 4 ceramics with the weak interlayer bonding. In this work, the influence of different debinding atmosphere on the pyrolysis process of organics in vat photopolymerization 3D printed Si 3 N 4 green parts was investigated. The results showed that the use of 95 vol% N 2 +5 vol% H 2 atmosphere can effectively inhibit the cracking during the debinding process, especially the wall thickness of the 3D printed defect-free Si 3 N 4 green body was successfully increased to 5 mm, and the obtained sintered Si 3 N 4 ceramics exhibited higher true densities and better mechanical properties. The debinding atmospheres proposed in the current work provided additional options of debinding atmosphere for achieving high-performance 3D printed Si 3 N 4 ceramics and are expected to be expanded to other photosensitive slurry systems, with the potential to enable the production of ceramic components with the larger wall thicknesses. [ABSTRACT FROM AUTHOR]

The development of biocompatible nanoparticles (NPs) with effective photothermal properties is essential for advancing biomedical applications. This study investigates the synthesis and characterization of lecithin-polypyrrole nanoparticles (LEC-PPy NPs) formed through near-infrared (NIR) irradiation. LEC-PPy NPs were prepared by mixing lecithin with varying concentrations of pyrrole monomer, followed by NIR irradiation to induce potential polymerization. Characterization techniques, including Dynamic Light Scattering (DLS), Zeta Potential Analysis, FTIR, XRD, and TEM, were employed. The prepared NPs demonstrated a photothermal response, reaching temperatures above around 43 °C under NIR exposure while exhibiting cell viability and minimal hemolysis. The biochemical tests of the cellular membrane potential and AHR further validate their biological response. This study highlights the implication of NIR-induced polymerization in producing biocompatible LEC-PPy NPs, which show potential for various biomedical applications. Further optimization and in vivo validation are necessary to realize their clinical potential. [ABSTRACT FROM AUTHOR]

Background: Gold nanoparticles can generate heat upon exposure to radiation due to their plasmonic properties, which depend on particle size and shape. This enables precise control over the release of active substances from polymeric pharmaceutical formulations, minimizing side effects and premature release. The technology of 3D printing, especially vat photopolymerization, is valuable for integrating nanoparticles into complex formulations. Method: This study aimed to incorporate gold nanospheres (AuNSs) and nanorods (AuNRs) into polymeric matrices using vat photopolymerization, allowing for controlled drug release with exposure to 532 nm and 1064 nm wavelengths. Results: The AuNSs (27 nm) responded to 532 nm and the NRs (60 nm length, 10 nm width) responded to 1064 nm. Niclosamide was used as the drug model. Ternary blends of Polyethylene Glycol Diacrylate 250 (PEGDA 250), Polyethylene Glycol 400 (PEG 400), and water were optimized using DesignExpert 11 software for controlled drug release upon specific wavelength exposure. Three matrices, selected based on solubility and printability, underwent rigorous characterization. Two materials achieved controlled drug release with specific wavelengths. Bilayer devices combining AuNSs and AuNRs demonstrated selective drug release based on irradiation wavelength. Conclusions: A pharmaceutical device was developed, capable of controlling drug release upon irradiation, with potential applications in treatments requiring delayed administration. [ABSTRACT FROM AUTHOR]

To determine the short-term (5 min) initial effects of a high-irradiance light-curing (LC) protocol on light transmission (LT%), radiant exposure (RE) and degree of conversion (DC%) of different bulk-fill resin-based composites (RBCs). Six bulk-fill composites with different viscosities were investigated: OBF (One Bulk Fill, 3 M), EB (Estelite bulkfill,Tokuyama), PFill, PFlow, ECeram and EFlow (PowerFill, Poweflow, Tetric EvoCeram bulkfill, Tetric Evoflow bulkfill, Ivoclar), subjected to different LC protocols: one ultra-high-intensity (3 W/cm2 −3 s via PowerCure LCU) and two conventional (1.2 W/cm2 −10 s and 20 s via PowerCure and Elipar S10 LCUs). Specimens (n = 5) were polymerized within their molds (ϕ5 mm × 4 mm depth) to determine LT% and RE at 4 mm using a MARC-LC spectrometer. For real-time DC% measurements by FTIR, similar molds were utilized. Data were analyzed by one-way ANOVA and Tukey post-hoc tests at 5 % significance. Regardless of the applied LC protocols, OBF and low-viscosity RBCs (EB, PFlow and EFlow) had the lowest and highest LT%, RE, DC% and RPmax, respectively. RE results of all RBCs were in the same sequence: Elipar-20 s > PCure-10 s > PCure-3 s. DC% of PFill and PFlow displayed no significant difference between the applied LC protocols (p > 0.05). The polymerization kinetic in all materials was well described by an exponential sum function (r2 varied between 0.85 and 0.98), showing a faster polymerization with the PCure-3 s protocol. The measurement of LT% and DC% at 5 min gave an insight into the developing polymerization process. The initial response of these bulk-fill composite to a high-irradiation protocol varied depending on their composition and viscosity, being faster for low viscosity materials. Nevertheless, even though multiple resin composites are designed to be efficient during photopolymerization, care should be taken when selecting materials/curing protocol. [ABSTRACT FROM AUTHOR]

Vanillyl alcohol has emerged as a widely used building block for the development of biobased monomers. More specifically, the cationic (photo‐)polymerization of the respective diglycidyl ether (DGEVA) is known to produce materials of outstanding thermomechanical performance. Generally, chain transfer agents (CTAs) are of interest in cationic resins not only because they lead to more homogeneous polymer networks but also because they strikingly improve the polymerization speed. Herein, the aim is to compare the cationic chain‐growth photopolymerization with the thermally initiated anionic step‐growth polymerization, with and without the addition of CTAs. Indeed, CTAs lead to faster polymerization reactions as well as the formation of more homogeneous networks, especially in the case of the thermal anionic step‐growth polymerization. Resulting from curing above the TG of the respective anionic step‐growth polymer, materials with outstanding tensile toughness (>5 MJ cm−3) are obtained that result in the manufacture of potential shape‐memory polymers. [ABSTRACT FROM AUTHOR]

Injectable and temperature-responsive Poly(N-Isopropylacrylamide) (PNIPAAm)/Chitosan composite hydrogels reinforced with cellulose nanocrystals (CNCs) were successfully fabricated via photopolymerization. 0.1–3% (w/v) of cellulose nanocrystals were incorporated into the PNIPAAm/chitosan matrix to form thermo-responsive injectable composite hydrogels. FT-IR spectra confirmed the successful formation of these hydrogels, highlighting the characteristic peaks PNIPAAm, chitosan and CNCs. The inclusion of CNCs led to a reduced pore size as compared to the control hydrogels. The mechanical properties of the hydrogel were characterized under various temperature conditions. Rheology tests showed that storage modulus (G′) increased significantly above 30 °C, indicating gel-like behavior. Thermogravimetric analysis showed thermal stability up to 300 °C. The volume phase transition temperatures (VPTT) of the hydrogels were found to be in the range of 34–38 °C, close to physiological body temperature. The equilibrium swelling ratio (ESR) of the CNC-containing hydrogels was higher than that of the control. In vitro studies with Human Dermal Fibroblast adult (HDFa) cells showed the hydrogels to be non-toxic, suggesting their potential for biomedical applications. [ABSTRACT FROM AUTHOR]

A 3D-printable polymer can provide an effective solution for developing piezoelectric structures. However, their nanocomposite formulation and 3D printing processability must be optimized for fabricating complex geometries with high printability. In the present study, we optimized the 3D-printable piezoelectric composite formulation for developing complex geometries by an additive manufacturing approach. The zinc oxide (ZnO) nanomaterial was synthesized by the hydrothermal method. The ZnO loading in the 3D-printed flexible resin was optimized to exhibit good interfacial adhesion and enable 3D printing. The lattice structure was fabricated to improve the piezoelectric response compared with the solid structure. The lattice structure block printed with 10 wt% ZnO showed a good piezoelectric response, with a linear increase in the generated output voltage for an increase in force. The maximum power density of 0.065 μW/cm2 was obtained under 12 N force at 1 Hz. The fabricated structure generated a peak–peak voltage of ~3 V with a foot heel strike. [ABSTRACT FROM AUTHOR]

In the current study, a new type of novel lattice structures with the concept of bio-mimicking three different nature-inspired designs from the honeycomb patterns, the overlapping phenomenon of the scales present on fish dermal layers, and scutes pattern observed from the top skin layers present on crocodile species are developed. These lattice structures are designed within a cubic volume of 30 mm. The design of lattice unit cells is made with two different geometrical sizes of 4 and 6 mm with different overlapping areas of 20, 30, 40, and 50% calculated from each cell area. All the unit cells' walls are maintained at 0.4 and 0.6 mm only. The specimens are modeled and manufactured through the VAT photopolymerization process, one of the significant additive manufacturing principles for great dimensional accuracy with negligible defects in 3D printing (3DP). The research approach used to develop lightweight bio-inspired structures has been laid out, starting with observing design that served as inspiration. The cured 3D-printed specimens are examined under quasi-static compressive loading carried out on all specimens as per ASTM 1621 standards to measure the crashworthiness response of designed specimens. The energy ingestion capacity of all the specimens is assessed. A good correlation is observed between the experimental and numerical results for better validation. The best design parameters among all 16 specimens are identified for applying energy absorption applications in the automobile and aviation fields in real-time. [ABSTRACT FROM AUTHOR]

Presented here is a detailed account of the development and implementation of macrocyclic cobaloxime complexes as sulfur-free, catalytic chain transfer agents (CTAs) in crosslinking photopolymerizations. Although much of this review is dedicated to understanding the fundamentals of catalytic chain transfer (CCT) in photopolymerizations, its impact on network topology and resultant mechanical properties, future goals of applying this technology to multimaterial 3D printing are also discussed. It is our long-term ambition for catalytic, sulfur-free CTAs to supplant existing consumptive, sulfur-based agents to provide new, unexplored, and not currently possible to fabricate photopolymeric materials with a specific eye towards application in dentistry, additive manufacturing, and responsive materials. 1 Introduction 2 History of Catalytic Chain Transfer (CCT) 3 Understanding Catalyst Purity and Chain Transfer Activity 4 Evidencing CCT in a Crosslinking Photopolymerization 5 Comparing Cobalt(II)-Catalysts to Other Relevant CTAs 6 Performance of Cobalt(II)-Catalysts in Commercial Resins 7 Limitations of Approach and Looking Forward [ABSTRACT FROM AUTHOR]

In this work, a bio-based resin of acrylated epoxidized soybean oil (AESO) mixed with three types of active diluents (Isoborneol methacrylates [IBOMA], tripropylene glycol diacrylate [TPGDA], and Ethoxylated trimethylolpropane triacrylate [ETPTA]) is used to form a protective UV-curable coating film on calcium alginate water-carrying microspheres (CA-WCMs). Calcium alginate microspheres (CAMs) have previously been used to encapsulate only ester soluble or oil-in-water core materials, thus limiting their application. After UV-curing with an increased active diluent dose, the pencil hardness, pendulum hardness, and mechanical strength of the CAMs increased. A photopolymerization kinetics study reveals that the maximum double bond (C=C) conversion rates of AESO-IBOMA, AESO-TPGDA, and AESO-ETPTA are 95, 92, and 86%, respectively, and the maximum conversion rate of C=C bond is 87% in their mixed system. Additionally, the water retention rate of the water-carrying microspheres (WCMs) increased with an increasing number of coating layers, plateauing after the number of layers exceeded four. The water retention is favorable, with more than 75% of the water stored for a duration of 50 days. Overall, the cost-effective and environmentally friendly method has shown encouraging results in the acquisition of water-absorbing CAMs, with the potential to overcome existing implementation constraints. [ABSTRACT FROM AUTHOR]

Poly(vinyl alcohol) (PVA) based hydrogels have gained more interest in the field of biomaterials because of their many biomedical uses (i.e., wound healing, drug delivery, and tissue engineering) and intrinsic physicochemical and biological characteristics. They can be made using a variety of synthetic techniques, but all of them are very time-consuming. Among them, photopolymerization also referred to as light-induced polymerization, has drawn a lot of attention because of its benefits, which include not requiring the use of solvents, easy and quick network formation, energy efficiency, quick processing, control over both space and time and reliability of crosslinking density and matrix strength. Ultraviolet (UV)-curable hydrogels containing PVA as a main component are gaining interest because of their excellent properties, including biodegradability, biocompatibility, less cytotoxicity and remarkable mechanical strength. This review highlights the significance of UV curable systems and their components, types, advantages and disadvantages of photoinitiators (PIs), UV curable monomers and their structures, properties of UV-cured PVA hybrid hydrogels, and their characterizations and applications in different fields. The photopolymerization mechanisms, tunable properties, and unique advantages of these hydrogels have been explored in detail. Furthermore, it sheds light on recent advancements in PVA-based hydrogels research and future exploration in this domain. [ABSTRACT FROM AUTHOR]

The need for rapid, on-site contaminant detection is becoming increasingly vital for tackling environmental and public health challenges. This study introduces an efficient method for detecting sulfamethoxazole (SMX), a widely used antibiotic with significant environmental implications. A cost-effective, scalable approach was developed using lab-on-paper devices integrated with molecularly imprinted polymers (MIPs), synthesized through an in situ photopolymerization process that was completed in just 10 min. Using only 2 mL of MIP solution enabled the efficient mass production of 100 disks. Traditional template extraction, which often takes hours or days, was reduced to just 10 min using a multichannel micropipette and absorbent fabric. The MIP-PAD achieved a limit of detection (LOD) of 0.8 µg/mL and a limit of quantification (LOQ) of 2.4 µg/mL, with measurements obtained using a smartphone-based colorimetric detection system. It exhibited excellent repeatability, with a relative standard deviation (RSD) of 3.26% across seven tests, high reusability for up to eight cycles, and recovery rates for real samples ranging from 81.24% to 99.09%. This method provides notable improvements in sensitivity, reproducibility, and environmental sustainability over conventional techniques. The user-friendly platform integrating smartphone-based colorimetric detection is highly practical for real-time applications, offering broad potential for environmental monitoring, food safety, and healthcare. [ABSTRACT FROM AUTHOR]

Current additive manufacturing (AM) techniques and methods, such as liquid-crystal display (LCD) vat photopolymerization, offer a wide variety of surface-sensing solutions, but customizable internal sensing is both scarce in presence and narrow in scope. In this work, a fabrication process for novel customizable embedded ceramic temperature sensors is investigated. The fabrication techniques and materials are evaluated, followed by extensive characterization via spectral analysis and thermomechanical testing. The findings indicate that LCD-manufactured ceramic sensors exhibit promising sensing properties, including strong linear thermal sensitivity of 0.23% per °C, with an R2 of at least 0.97, and mechanical strength, with a hardness of 570 HV, making them suitable for adverse environmental conditions. This research not only advances the field of AM for sensor development but also highlights the potential of LCD technology in rapidly producing reliable and efficient ceramic temperature sensors. [ABSTRACT FROM AUTHOR]

The article discusses the integration of 3D printing technology into chemistry lessons, highlighting its benefits in creating high-quality teaching materials and educational games at a lower cost. It explores the use of 3D printing as a learning tool to understand plastics and resin printers, promoting digital skills relevant for teachers and students. The article also delves into the process of creating 3D-printed objects and the chemical background of resin printing, focusing on the application of radical polymerization in the classroom. [Extracted from the article]

The photoATRP of methyl acrylate (MA) is investigated using riboflavin (RF) and CuBr2/Me6TREN as a dual catalyst system under green LED irradiation (λ ≈ 525 nm). Both RF and CuBr2/Me6TREN enhanced oxygen tolerance, enabling effective ATRP in the presence of residual oxygen. High molar mass polymers (up to Mn ≈ 129 000 g·mol−1) with low dispersity (Đ ≤ 1.16) are prepared, and chain‐end fidelity is confirmed through successful chain extension. The molecular masses of the obtained polymer increased linearly with conversion and showed high initiation efficiency. Mechanistic studies by laser flash photolysis reveal that the predominant activator generation mechanism is reductive quenching of RF by Me6TREN (83%, under [CuBr2]/[Me6TREN] = 1/3 condition), supported by polymerization kinetics and thermodynamic calculations. [ABSTRACT FROM AUTHOR]

Integration of lead‐halide perovskite quantum dots (PQDs) into full‐color microarrays presents numerous advantages for full‐color micro‐LED displays. There is an urgent requirement for a new design approach that simplifies the creation of durable PQD/polymer composites to produce stable PQD microarrays. Here, mono‐2‐(methacryloyloxy)ethyl succinate (MMeS) is utilized as a functional ligand to synthesize green MMeS‐modified CsPbBr3 PQDs (M‐CPB PQDs). The subsequent photopolymerization of M‐CPB PQDs with 1,6‐hexanediol diacrylate (HDDA) forms a CsPbBr3 PQD/polymer composite. This composite exhibits a solid‐state photoluminescence quantum yield of 73.1%, and the photoluminescence intensity retains 72% of its original value after 17 days of continuous immersion in water. Stable green PQD/polymer microarrays can be printed using an ink containing M‐CPB PQDs, HDDA, diphenyl (2,4,6‐trimethylbenzoyl) phosphine oxide, and n‐dodecane via electrohydrodynamic jet printing and in situ polymerization under UV light irradiation. Full‐color patterns can also be generated with MMeS‐modified red, green, and blue PQDs. These findings highlight the critical role of functionalizing the surface ligands of PQDs to improve their processability, thereby facilitating the development of stable PQD/polymer microarrays. [ABSTRACT FROM AUTHOR]

Alternating copolymers are crucial for diverse applications. While dispersity (Ð, also known as molecular weight distribution, MWD) influences the properties of polymers, achieving low dispersities in alternating copolymers poses a notable challenge via free radical polymerizations (FRPs). In this work, we demonstrated an unexpected discovery that dispersities are affected by the participation of charge transfer complexes (CTCs) formed between monomer pairs during free radical alternating copolymerization, which have inspired the successful synthesis of various alternating copolymers with low dispersities (>30 examples, Ð=1.13–1.39) under visible‐light irradiation. The synthetic method is compatible with binary, ternary and quaternary alternating copolymerizations and is expandable for both fluorinated and non‐fluorinated monomer pairs. DFT calculations combined with model experiments indicated that CTC‐absent reaction exhibits higher propagation rates and affords fewer radical terminations, which could contribute to low dispersities. Based on the integration of Monte Carlo simulation and Bayesian optimization, we established the relationship map between FRP parameter space and dispersity, further suggested the correlation between low dispersities and higher propagation rates. Our research sheds light on dispersity control via FRPs and creates a novel platform to investigate polymer dispersity through machine learning. [ABSTRACT FROM AUTHOR]

Functional polyvinylethylene glycols (PVEGs) with pendent vinyl groups were synthesized by Pd/B synergistic catalysts and their structures were characterized by 1H NMR and FT‐IR. The photopolymerization of the obtained PVEGs with multifunctional thiols in the presence of a photoinitiator proceeded smoothly via thiol‐ene photo‐click reaction to give a series of crosslinked materials by the variation of the molecular weight of PVEGs and a ratio of thiols and enes. The curing behavior was studied by FT‐IR and the properties of crosslinked materials were characterized by the test of gel content, swelling ratio, and water absorption. The dynamic mechanical analysis, mechanical properties, thermogravimetry, and surface properties of the crosslinked materials were investigated and the performance of coating for the crosslinked film materials was also characterized. The crosslinked film materials can be further functionalized by post‐crosslinking modification through thiol‐ene photo‐click reaction. [ABSTRACT FROM AUTHOR]

Thio-benzothioxanthene imide (BTXI) exhibits long excited state lifetime (τT = 17.7 μs) and high ISC efficiency (ΦΔ = 97%). For the first time, BTXI derivatives were used as photosensitizers for triplet–triplet annihilation upconversion, achieving the highest efficiency of 13.8%. In addition, thio-BTXI derivatives were used as photoinitiators for photopolymerization, resulting in a series of green light-activated radical polymerization systems. [ABSTRACT FROM AUTHOR]