Search

A material capable of curing due to UV irradiation based on an alkyd oligomer and oligoorganosilsesquioxanes (OOSs) with functional thiol groups was obtained. Using microinterferometry, it was shown that the alkyd oligomer and OOS are completely compatible (mutually soluble). The resulting alkyd‐siloxane composition was cured under the action of UV irradiation due to reaction between double bonds of alkyd oligomer and thiol‐groups of silsesquioxane oligomer. The curing reaction takes 5 min with formation of coating, containing 99% of gel fraction, which is in 30 times faster in comparison with the classical method of alkyd curing in the presence of siccatives. The hydrophobicity of alkyd‐siloxane coatings also increases and varies depending on the content of OOS. The introduction of 50% OOS into the alkyd oligomer makes it possible to increase the water contact angle by 10° relative to the coating based on pure alkyd. A similar dependence is observed when studying the thermal stability of coatings. Thus, even with the introduction of 10% OOS into alkyd oligomer, the temperature at which a loss of 50% of mass occurs increases by 24°C relative to coatings based on a pure alkyd oligomer. [ABSTRACT FROM AUTHOR]

We report an anomalous structural transformation of a Cu(I) cluster into two different types of copper‐silver (CuAg) alloy nanoclusters. Different from previous reports, we demonstrate that under specifically designed reaction conditions, the Ag‐doping could induce a substantial growth of the starting Cu15 and a Ag13Cu20 nanocluster was obtained via the unexpected insertion of an Ag13 kernel inside the Cu(I)‐S shell. Ag13Cu20 demonstrates high activity to initiate the photopolymerization of previously hard‐to‐print inorganic polymers in 3D laser microprinting. Interestingly, a slight modification of the reaction condition leads to the formation of another Ag18‐xCuxS (8≤x) nanocluster templated by a central S2− anion, which possesses a unique electronic structure compared to conventional template‐free CuAg nanoclusters. Overall, this work unveils the intriguing doping chemistry of Cu clusters, as well as their capability to create different types of alloy nanoclusters with previously unobtainable structures and multifunctionality. [ABSTRACT FROM AUTHOR]

We report an anomalous structural transformation of a Cu(I) cluster into two different types of copper‐silver (CuAg) alloy nanoclusters. Different from previous reports, we demonstrate that under specifically designed reaction conditions, the Ag‐doping could induce a substantial growth of the starting Cu15 and a Ag13Cu20 nanocluster was obtained via the unexpected insertion of an Ag13 kernel inside the Cu(I)‐S shell. Ag13Cu20 demonstrates high activity to initiate the photopolymerization of previously hard‐to‐print inorganic polymers in 3D laser microprinting. Interestingly, a slight modification of the reaction condition leads to the formation of another Ag18‐xCuxS (8≤x) nanocluster templated by a central S2− anion, which possesses a unique electronic structure compared to conventional template‐free CuAg nanoclusters. Overall, this work unveils the intriguing doping chemistry of Cu clusters, as well as their capability to create different types of alloy nanoclusters with previously unobtainable structures and multifunctionality. [ABSTRACT FROM AUTHOR]

Supramolecular assemblies with chirality inversion were developed using a co-assembly system comprising solvent monomers and a pyridine-cholesterol gelator. The polarity-dependent chiralities were captured in situ through photopolymerization, enabling the formation of multi-color circularly polarized luminescence films. [ABSTRACT FROM AUTHOR]

A novel photopolymerizable (meth)acrylate oligomer syrup modified with ferulic acid (FA) was verified as an antimicrobial coating binder against a biofilm of Staphylococcus epidermidis. A solution-free UV-LED-initiated photopolymerization process of aliphatic (meth)acrylates and styrene was performed to prepare the oligomer syrup. The influence of ferulic acid on the UV crosslinking process of the varnish coatings (kinetic studies using photo-DSC) as well as their chemical structure (FTIR) and mechanical (adhesion, hardness), optical (gloss, DOI parameter), and antibacterial properties against S. epidermidis were investigated. The photo-DSC results revealed that FA has a positive effect on reducing the early occurrence of slowing processes and has a favorable effect on the monomer conversion increment. It turned out, unexpectedly, that the more FA in the coating, the greater its adhesion to a glass substrate and hardness. The coating containing 0.9 wt. part of FA exhibited excellent antimicrobial properties against S. epidermidis, i.e., the bacterial number after 24 h was only 1.98 log CFU/mL. All the coatings showed relatively high hardness, gloss (>80 G.U.), and DOI parameter values (30–50 a.u.). [ABSTRACT FROM AUTHOR]

The development of highly efficient, solution-processable, and environmentally stable perovskite quantum dots (PQDs) is crucial for their accurate high-resolution patterning and subsequently enabling the practical deployment of PQD based emissive display devices. This study presents an innovative strategy for integrating all-inorganic PQDs and ultraviolet (UV) crosslinkable acrylate polymer at a structural and functional level. The achievement is accomplished by meticulous design and one-pot synthesis of UV-crosslinkable CsPbX3 (X = Cl, Br, I) PQDs solution, which exhibit outstanding environmental stability. Leveraging the solution-processable characteristics of the resulting UV-crosslinkable PQDs, precise patterning of high-resolution (2 µm, 7608 pixels in.−1) and colorful PQDs microarrays can be readily achieved through inkjet printing and high-throughput photolithography (~ 2 µm in pitch line/space patterning). The UV cross-linked process guarantees a homogeneous distribution of PQDs, effectively mitigating coffee ring effect and improving the overall quality of stereoscopic microarrays. The photo-cured PQDs film, which undergoes free radical photopolymerization, displays an impressive photoluminescence quantum yield (PL QY) of up to 89.2%, reaching 98% of the value observed in the solution state. The approach outlined in this research is both cost-effective and pragmatic, exhibiting tremendous promise for diverse system-level integrated optoelectronic devices, such as ultra-high-resolution micro-light-emitting device (micro-LED) displays. [ABSTRACT FROM AUTHOR]

In this study, synthesis, characterization and photopolymerization of new type of castor oil-based monomer family are studied. Electrical properties of the synthesized polymers are also evaluated. The synthesis of these materials consists of two steps. Acrylation of the castor oil and methyl ricinoleate occur in the first step and epoxidation is then followed. Epoxidized acrylated castor oil (EACO) and epoxidized acrylated methyl ricinoleate (EAMR) are synthesized at the end of the reactions. FTIR (Fourier transform infrared) and 1H NMR (nuclear magnetic resonance) spectroscopy techniques are used to characterize of the starting materials and monomers. When acrylate groups are introduced to castor oil and methyl ricinoleate, a characteristic peak at 1722 cm−1 is observed in FTIR spectrum and peaks of acrylate hydrogens at 5.7, 6.0 and 6.3 are observed in 1H NMR spectrum. After epoxidation, a small peak is detected at 840 cm−1 in FTIR spectrum and new peaks appear at 2.5 and 3.0 ppm in 1H NMR spectrum. Photopolymerization of the synthesized materials are performed with DMPA (2,2-dimethoxy-2-phenylacetophenone) and AIBN (azobisisobutyronitrile) catalyst. It is found that DMPA catalyst is more effective than AIBN. EACO samples' DC (direct current) resistance and conductance values are measured as 146.4 MΩm and 6.83 nS/m, respectively, whereas EAMR samples' DC resistance and conductance values are calculated as 96 MΩm and 10.42 nS/m, respectively. AC (alternative current) analysis is conducted by using LCR meter for the polymeric samples where EACO samples' capacitances varies from 4.88 to 3.29 pF (picofarads) with respect to frequency (10 Hz–300 kHZ). On the other hand, EAMR samples' capacitances varies from 14.7 to 6.49 pF with respect to frequency. Impedance values of the EACO samples with respect to frequency are measured as 4.24 GΩ and 165 kΩ, respectively. Impedance values of the EAMR samples with respect to frequency are measured as 1.19 GΩ and 82 kΩ, respectively. [ABSTRACT FROM AUTHOR]

Controlled radical polymerization (CRP) techniques enable the preparation of diverse, chemically tailored polymers with a variety of chain architectures. Separately, light‐mediated polymerization reactions offer a number of advantages over thermal polymerizations in terms of energy efficiency, sustainability, and versatility. Recent work has combined photopolymerization and CRP techniques to advance the synthesis of polymers with nonlinear architectures, including bottlebrush polymers, star polymers, hyperbranched polymers, and cyclic polymers. These photoCRP methods offer novel routes to nonlinear polymers using mild reaction conditions. In this review, we provide an overview of photoCRP techniques for the synthesis of nonlinear polymers. We start with a discussion of photoCRP applied to the synthesis of linear polymers and discuss the underlying reaction mechanisms. Then, we discuss photoCRP applied to the synthesis of bottlebrush, star, hyperbranched, cyclic, and surface‐initiated polymer brushes. For each case, we discuss the synthetic strategy and the unique properties and characteristics of the resulting polymers, and we provide a perspective on potential future directions for research. [ABSTRACT FROM AUTHOR]

In this work, six benzothioxanthene‐based oxime esters were employed as photoinitiators for photopolymerization under visible light (LED) and sunlight. Their abilities to behave as Type I photoinitiators by mean of a photocleavage mechanism of oxime esters but also in multicomponent photoinitiating systems with an iodonium salt (through an electron transfer mechanism) were both explored with the different structures. Due to their broad absorption spectra tailing up 600 nm, photoinitiating properties of the benzothioxanthene‐based oxime esters were systematically tested under excitation with low‐intensity LED light at wavelengths of 405 nm and 450 nm. Additionally, parallel to the polymerization tests done under artificial light, the different benzothioxanthene‐based oxime esters were also investigated as solar photoinitiators and displayed a high reactivity in France (Western Europe) even in winter conditions. For the best candidates i.e. the most reactive structures, direct laser write experiments were carried out, evidencing the interest of these structures. [ABSTRACT FROM AUTHOR]

In this work, six benzothioxanthene‐based oxime esters were employed as photoinitiators for photopolymerization under visible light (LED) and sunlight. Their abilities to behave as Type I photoinitiators by mean of a photocleavage mechanism of oxime esters but also in multicomponent photoinitiating systems with an iodonium salt (through an electron transfer mechanism) were both explored with the different structures. Due to their broad absorption spectra tailing up 600 nm, photoinitiating properties of the benzothioxanthene‐based oxime esters were systematically tested under excitation with low‐intensity LED light at wavelengths of 405 nm and 450 nm. Additionally, parallel to the polymerization tests done under artificial light, the different benzothioxanthene‐based oxime esters were also investigated as solar photoinitiators and displayed a high reactivity in France (Western Europe) even in winter conditions. For the best candidates i.e. the most reactive structures, direct laser write experiments were carried out, evidencing the interest of these structures. [ABSTRACT FROM AUTHOR]

A new type polymeric adsorbent, poly(allylphenol‐co‐hydroxyethyl methacrylate‐co‐vinyl imidazole) (PAHV), is synthesized in this study. 2‐Hydroxyethyl methacrylate is used as complementary monomers along with 1‐vinyl imidazole and allylphenol monomers. The photopolymerization method is preferred as a synthesis method and benzophenone is used as the photoinitiator. The effectiveness of the PAHV against bacterial species such as Escherichia coli and Staphylococcus aureus is investigated by the Clinical and Laboratory Standards Institute (CLSI) disk diffusion method. The inhibition areas of PA1H1V3 and PA1H1V1 derivatives against E. coli and S. aureus are measured as 25 mm ± 0.25 mm and 7 mm ± 0.1 mm; 20 mm ± 0.25 mm, and 5 mm ± 0.1 mm, respectively. Sorption efficiencies (%) at pH = 6 (selected optimum pH) for 100 μg/L Cd and Cr of the PA1H1V1, PA1H3V1, and PA1H1V3 derivatives are found to be 69.0 ± 2.7 and 58.3 ± 6.7, 66.8 ± 6.2 and 75.8 ± 5.5, and 97.2 ± 3.7 and 97.7 ± 3.2 (n = 3), respectively. Adsorption studies revealed that the PA1H1V3 polymer can be used as an alternative for the sorption of cadmium and chromium. The pseudo‐second‐order model and Langmuir isotherm model fits for both adsorption processes. The adsorption capacities obtained from the Langmuir isotherm model for chromium and cadmium sorption are 52.63 and 68.49 μg g−1, respectively. [ABSTRACT FROM AUTHOR]

Trees grow by coupling the transpiration‐induced nutrient absorption from external sources and photosynthesis‐based nutrient integration. Inspired by this manner, we designed a class of polyion complex (PIC) hydrogels containing isolated liquid‐filled voids for growing texture surfaces. The isolated liquid‐filled voids were created via irreversible matrix reconfiguration in a deswelling‐swelling process. During transpiration, these voids reversibly collapse to generate negative pressures within the matrices to extract polymerizable compounds from external sources and deliver them to the surface of the samples for photopolymerization. This growth process is spatial‐controllable and can be applied to fabricate complex patterns consisting of different compositions, suggesting a new strategy for making texture surfaces. [ABSTRACT FROM AUTHOR]

Trees grow by coupling the transpiration‐induced nutrient absorption from external sources and photosynthesis‐based nutrient integration. Inspired by this manner, we designed a class of polyion complex (PIC) hydrogels containing isolated liquid‐filled voids for growing texture surfaces. The isolated liquid‐filled voids were created via irreversible matrix reconfiguration in a deswelling‐swelling process. During transpiration, these voids reversibly collapse to generate negative pressures within the matrices to extract polymerizable compounds from external sources and deliver them to the surface of the samples for photopolymerization. This growth process is spatial‐controllable and can be applied to fabricate complex patterns consisting of different compositions, suggesting a new strategy for making texture surfaces. [ABSTRACT FROM AUTHOR]

Connecting optical components in a highly precisely aligned manner that avoids significant losses due to misalignment is an important objective for future light-based high-speed data transmission technologies. We fabricated multimode light-induced self-written (LISW) optical waveguides using near-infrared (NIR) light for multimode optical component self-coupling. Multimode optical fibers were optically soldered with NIR light (≤ 1 mW) using this waveguide, with an insertion loss of only 0.69 dB observed when soldered at 0.6 mW. [ABSTRACT FROM AUTHOR]

Photopolymerization is becoming increasingly popular in industry due to its copious advantages. The vital factor in the entire pre-polymerization formulation is the presence of photoinitiators. Depending on the application, photoinitiators have different features. Hence, scientists are particularly interested in developing new photoinitiators that can expand the scope of applications and be used to create products with the features demanded by current trends. This brief review summarizes the photoinitiators used in dental materials and hydrogels and those obtained from natural and synthetic sources. [ABSTRACT FROM AUTHOR]

Functionally graded materials (FGMs) have spatial variations in structure or composition that result in gradients in their mechanical, thermal, swelling, or other properties. FGMs have garnered significant research interest because of their extensive applications in areas such as biomedical implants, sensors, and soft robotics. Recently, grayscale photopolymerization 3D printing has emerged as a promising technology for crafting complex and high‐resolution FGMs. This comprehensive work delves into various grayscale photopolymerization 3D printing techniques, offering insights into their ability to precisely control printing exposure energy and polymerization degree, which in turn influence material properties. Furthermore, this work highlights diverse applications of grayscale vat‐photopolymerization 3D printing. Finally, it offers perspectives on ways to enhance grayscale photopolymerization 3D printing, with a focus on improving printing feedstocks and grayscale strategies. [ABSTRACT FROM AUTHOR]

Rapid manufacturing of medical devices during unforeseen pandemics is imperative. In striving for manufacturing efficiency, photopolymerization has emerged as a viable approach for diverse healthcare applications in recent decades. Photopolymerization‐based 3D printing offers significant potential with a range of biocompatible materials (e.g., poly(ethylene glycol), cellulose, etc.) while minimizing waste generation. However, prevalent commercial photoinitiators used in this process are synthetic and environmentally unfriendly. Therefore, the naturally occurring and derived photoinitiators have drawn tremendous research interest due to their bioactivities and inherent environmental safety. This review comprehensively outlines the medical applications implemented by these photoinitiators, highlighting their inherent photoinitiation abilities. Moreover, it delves into the impact of substituent effects on the photoinitiation abilities of naturally derived photoinitiators. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) printing is an innovative manufacturing method with the potential to revolutionize topical and transdermal dosage forms. Nowadays, it is established that Vatbased photopolymerization (VP) 3D printing technologies offer superior printing efficiency and versatility compared to other 3D printing technologies available on the market. However, there are some limitations that impair their full application in pharmaceutical contexts, such as the lack of a range of biocompatible materials for topical and transdermal applications. This review article explores all types of VP-based 3D printing and discusses the relevance of implementing this kind of technology. We start with a detailed description of the printing process, focusing on the commercial materials available and lab-made resins proposed by different authors. We also review recent studies in this field, which mainly focus on the fabrication of transdermal devices based on microneedle arrays. In the future, it is expected that the manufacturers of 3D printers invest in modifications to the printing apparatus to allow the simultaneous printing of different resins and/or compound types, which will open frontiers to the personalization of treatment approaches. [ABSTRACT FROM AUTHOR]

The complex ceramic core used for hollow turbine blades requires high porosity and flexural strength. This work combined vat photopolymerization 3D printing with sacrificial template method to prepare Al2O3 ceramic cores with strip‐shaped pores using polyamide 6 (PA6) fibers as templates. When the porosity was greater than 30%, the maximum flexural strength reached up to 110.48 MPa. The sacrificial templating method improved the porosity of Al2O3 ceramic cores, forming an internal porous structure that combined strip‐shaped large pores with irregularly shaped small pores. The influences of PA6 fiber content and diameter on the shrinkage, porosity, microstructure, and comprehensive properties of alumina ceramic cores were studied, revealing the mechanism of the coexistence of high porosity and high strength. [ABSTRACT FROM AUTHOR]

The photolysis of a phenanthroline-containing imidazole in a DMSO solution and the initiating ability of the compound in the photopolymerization of multifunctional (meth)acrylates under LED irradiation (λ = 395 nm) in aerobic conditions have been studied for the first time. The relationship between the kinetic parameters of photopolymerization and light intensity and the chemical structure and viscosity of multifunctional monomers has been established. [ABSTRACT FROM AUTHOR]

The acrylates with oligomers and monomers from (partially) bio‐based feedstock become available at (semi‐)industrial scale, which can be processed through photochemical crosslinking for applications in coatings, additive manufacturing, electronics, or inks. Although fossil‐ and bio‐based acrylates may have a similar chemical composition, it requires good understanding of processing and structure–property relationships as minor changes in microstructure may strongly alter the performance. A comparative study on mechanical properties and chemical structure of bio‐ and fossil‐based acrylates with different functionalities and backbone structures reveals higher ductility of bio‐based acrylates, in relation with a more complex organization of the intrinsic molecular structure. The latter is confirmed by mechanical testing and visco‐elastic characteristics (dynamic mechanical analysis) yielding lower stiffness and higher dampening of bio‐based acrylates, in parallel with a lower glass transition temperature (differential scanning calorimetry). The complex molecular arrangements include a nanoscale morphology with ordered structure (X‐ray diffraction), conformational changes (infrared spectroscopy), and a residual high‐molecular weight fraction (size exclusion chromatography). The visco‐elastic calculations indicate only 4% to 5% lower crosslinking density and around 10% higher mean molar mass of the polymer chains segments between chemical crosslinks and trapped chain entanglements, which explain the unique structure and performance of bio‐based acrylates. [ABSTRACT FROM AUTHOR]

Polymer-based materials, such as polyethylene glycol and its derivatives, are popular as biomaterials, including for clinical purposes. The hydrogels used in drug-carrying systems have become beneficial in cancer therapy. Due to their unique biocompatibility, durability, enhanced drug loading capacity, and low cytotoxicity, poly(ethylene glycol) dimethacrylate (PEGDMA) hydrogels are widely used in drug delivery systems. In this work, we illustrated the photopolymerization of four PEGDMA/methyl cellulose (MC) hydrogels at four concentrations. Irgacure 2959 (2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone) was used as a UV photoinitiator. Various aspects of the properties of hydrogels were studied. Fourier-transform infrared spectroscopy (FTIR) was used for the chemical bonds, scanning electron microscopy (SEM) for the surface morphology, and differential scanning calorimetry (DSC) to identify the thermal behavior, and swelling, contact angle, and degradation tests were executed to understand the hydrogels' behavior against moisture. Cancer cells' ability to grow and proliferate on PEGDMA hydrogels was examined to assess the hydrogels' viability as a drug carrier system for tissue engineering applications. The results suggest that the F4 hydrogels present a novel all-round means of cell culture and drug delivery as they permit target drug delivery and exhibit nontoxic behavior due to their high swelling ratio, good degradation profile, and biocompatibility, confirming that these hydrogels are suitable for further applications in cell culture analysis. [ABSTRACT FROM AUTHOR]

A new type of UV-curable pressure-sensitive adhesive containing Si atoms (Si-PSAs) was prepared by a solution-free UV-initiated telomerization process of n-butyl acrylate, acrylic acid, methyl methacrylate, and 4-acrylooxybenzophenone using triethylsilane (TES) as a telogen and an acylphosphine oxide (APO) as a radical photoinitiator. Selected commercial adhesion promoters were tested as additives in the formulation of adhesive compositions, i.e., (i) an organic copolymer with polar groups (carboxyl and hydroxyl); (ii) a hydroxymetal-organic compound; and (iii) a quaternary ammonium salt and (iv) a chlorinated polyolefin. No fillers, crosslinking agents, or photoinitiators were used in the adhesive compositions. NMR techniques confirmed the incorporation of silicon atoms into the polyacrylate structure. The influence of adhesion promoters on the kinetics of the UV-crosslinking process of Si-PSAs was investigated by a photo-DSC technique. The obtained Si-PSAs were characterized by adhesion (to steel, glass, PMMA, and PE), tack, and cohesion at 20 °C. Finally, the wetting angle of Si-PSAs with water was checked and their thermal stability was proved (TGA). Unexpectedly, the quaternary ammonium salt had the most favorable effect on improving the thermal stability of Si-PSAs (302 °C) and adhesion to glass and PMMA. In contrast, Si-PSAs containing the hydroxymetal-organic compound showed excellent adhesion to steel. [ABSTRACT FROM AUTHOR]

Additive manufacturing is the state‐of‐the‐art method for producing complex ceramic parts. For cellular materials, the freedom of design is particularly advantageous, as pore networks and shapes can be tailored. Herein, the direct printing of complex parts with high porosity using the cost‐effective manufacturing method of Liquid Crystal Display‐based stereolithography on low‐cost printers is determined. It is investigated how the architecture of the alumina Kelvin cells topology, their fabrication process, the printing parameters, and the microstructure affect the accuracy and mechanical properties of the printed samples. A notable reduction to a strut thickness of Kelvin cells down to 0.20 mm is achieved corresponding to a reduction of 1.5 compared with the state‐of‐the‐art literature (min. 0.35 mm). Ultrahigh porosities between 89.5% and 97.2% and a maximum compressive strength of 1.84 ± 0.17 MPa are reached due to the dense struts of the structure. Low‐cost and simple vat ceramic photopolymerization with high accuracy printing proves to be a promising candidate for the rapid and cost‐effective fabrication of highly porous and complex ceramic structures. [ABSTRACT FROM AUTHOR]

Today, controlling the photopolymerization process during the 3D printing in vat photopolymerization is a key challenge. In this work, it is shown that using a relatively limited set of parameter, it is possible to estimate key factors involved in such process. On the basis of 16 formulations containing different concentrations of photoinitiator and UV filter, attempt was made to rationalize the photonic parameters used in the 3D printing process, that is, the depth of penetration Dp and the critical energy Ec. It is shown that the experimental Dp values can be correlated with calculated ones from Bouguer–Beer–Lambert law. Real‐time Fourier‐transform infrared spectroscopy (RT‐FTIR) experiments were performed under similar conditions as in 3D printing. The conversion profiles were used to estimate the Ec values. The limits of this approach was discussed as a function of the UV filter concentration. Finally, the RT‐FTIR curves are exploited to predict the in‐depth conversion of the different 3D printed layers and compared to experimental results obtained by confocal Raman microscopy. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Currently, most photoredox catalysis polymerization systems are limited by high excitation power, long polymerization time, or the requirement of electron donors due to the precise design of efficient photocatalysts still poses a great challenge. Herein, we propose a new approach: the creation of efficient photocatalysts having low ground state oxidation potentials and high excited state energy levels, along with through‐space charge transfer (TSCT) induced intersystem crossing (ISC) properties. A cabazole‐naphthalimide (NI) dyad (NI‐1) characterized by long triplet excited state lifetime (τT=62 μs), satisfactory ISC efficiency (ΦΔ=54.3 %) and powerful reduction capacity [Singlet: E1/2 (PC+1/*PC)=−1.93 eV, Triplet: E1/2 (PC+1/*PC)=−0.84 eV] was obtained. An efficient and rapid polymerization (83 % conversion of 1 mM monomer in 30 s) was observed under the conditions of without electron donor, low excitation power (10 mW cm−2) and low catalyst (NI‐1) loading (<50 μM). In contrast, the conversion rate was lower at 29 % when the reference catalyst (NI‐4) was used for photopolymerization under the same conditions, demonstrating the advantage of the TSCT photocatalyst. Finally, the TSCT material was used as a photocatalyst in practical lithography for the first time, achieving pattern resolutions of up to 10 μm. [ABSTRACT FROM AUTHOR]

Currently, most photoredox catalysis polymerization systems are limited by high excitation power, long polymerization time, or the requirement of electron donors due to the precise design of efficient photocatalysts still poses a great challenge. Herein, we propose a new approach: the creation of efficient photocatalysts having low ground state oxidation potentials and high excited state energy levels, along with through‐space charge transfer (TSCT) induced intersystem crossing (ISC) properties. A cabazole‐naphthalimide (NI) dyad (NI‐1) characterized by long triplet excited state lifetime (τT=62 μs), satisfactory ISC efficiency (ΦΔ=54.3 %) and powerful reduction capacity [Singlet: E1/2 (PC+1/*PC)=−1.93 eV, Triplet: E1/2 (PC+1/*PC)=−0.84 eV] was obtained. An efficient and rapid polymerization (83 % conversion of 1 mM monomer in 30 s) was observed under the conditions of without electron donor, low excitation power (10 mW cm−2) and low catalyst (NI‐1) loading (<50 μM). In contrast, the conversion rate was lower at 29 % when the reference catalyst (NI‐4) was used for photopolymerization under the same conditions, demonstrating the advantage of the TSCT photocatalyst. Finally, the TSCT material was used as a photocatalyst in practical lithography for the first time, achieving pattern resolutions of up to 10 μm. [ABSTRACT FROM AUTHOR]

Creatures, such as Venus flytrap and hummingbirds, capable of rapid predation through snap‐through transition, provide paradigms for the design of soft actuators and robots with fast actions. However, these artificial "snappers" usually need contact stimulations to trigger the flipping. Reported here is a constrained anisotropic poly(N‐isopropylacrylamide) hydrogel showing fast snapping upon light stimulation. This hydrogel is prepared by flow‐induced orientation of nanosheets (NSs) within a rectangular tube. The precursor containing gold nanoparticles is immediately exposed to UV light for photopolymerization to fix the ordered structure of NSs. Two ends of the slender gel are clamped to form a buckle with bistability nature, which snaps to the other side upon laser irradiation. Systematic experiments are conducted to investigate the influences of power intensity and irradiation angle of the laser, as well as thickness and buckle height of the gel, on the snapping behaviors. The fast snapping is further used to kick a plastic bead and control the switch state. Furthermore, synergetic or oscillated snapping of the gel with two buckles of opposite directions is realized by inclined irradiation of a laser or horizontal irradiation with two lasers, respectively. Such light‐steered snapping of hydrogels should merit designing soft robots, energy harvests, etc. [ABSTRACT FROM AUTHOR]

Vat photopolymerization (VP) additive manufacturing enables fabrication of complex 3D objects by using light to selectively cure a liquid resin. Developed in the 1980s, this technique initially had few practical applications due to limitations in print speed and final part material properties. In the four decades since the inception of VP, the field has matured substantially due to simultaneous advances in light delivery, interface design, and materials chemistry. Today, VP materials are used in a variety of practical applications and are produced at industrial scale. In this perspective, we trace the developments that enabled this printing revolution by focusing on the enabling themes of light, interfaces, and materials. We focus on these fundamentals as they relate to continuous liquid interface production (CLIP), but provide context for the broader VP field. We identify the fundamental physics of the printing process and the key breakthroughs that have enabled faster and higher-resolution printing, as well as production of better materials. We show examples of how in situ print process monitoring methods such as optical coherence tomography can drastically improve our understanding of the print process. Finally, we highlight areas of recent development such as multimaterial printing and inorganic material printing that represent the next frontiers in VP methods. [ABSTRACT FROM AUTHOR]

UV-activated catalytic hydrosilation is a low-temperature crosslinking process that has attracted attention for its high efficiency and lower energy demand relative to thermal curing. In this study, formulations comprising industrially relevant model silanes and Pt photocatalysts trimethyl(methylcyclopentadienyl)platinum(IV) and trimethyl(pentamethylcyclopentadienyl)platinum(IV) (MeCpPtMe3 and Cp*PtMe3, respectively) were prepared with and without a photosensitizer (PS) and assessed for catalytic performance by a novel strategy. Photopolymerizations were initiated using different wavelengths from LEDs and monitored in real-time using an Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) "well" strategy to track the degree of cure in ultra-thin films by consumption of hydride via the disappearance of the Si-H bending absorption band at 915 cm−1. Irradiation of formulations with 365 nm excitation showed higher conversions relative to 400 nm light and improvements to calculated initial reaction rates by incorporation of a PS suggested increased sensitization to 365 nm irradiation. To the best of our knowledge, this is the first study to report catalytic performance, electronic absorption spectroscopic data, and the crystal structure of Cp*PtMe3. [ABSTRACT FROM AUTHOR]

In the field of wound healing treatment, the development of new materials is essential to cover multiple functions, such as acceleration of the healing process, prevention of infection and response to stimuli, especially if they present lower costs or are easier to manufacture. These properties are of great importance to prompt skin cicatrization. In this work, new multifunctional skin dressings for wound healing and infection prevention are developed based on new hydrogel materials. The dressings are produced via a straightforward and environmentally friendly one‐pot photopolymerization manufacturing process utilizing vitamin B2 aqueous solutions as sensitizer, and energy‐efficient blue light sources. These dressings exhibit a high swelling capacity, pH and temperature responsiveness, biocompatibility, antimicrobial activity in the absence of conventional antibiotics, and are capable of promoting wound healing. The formulation is based on the combination of three monomers: 2‐((methacryloyloxy)ethyl)trimethylammonium chloride, methacrylic acid and N‐vinyl caprolactam. Collagen, hyaluronic acid, and essential oil of hop are added to enhance antimicrobial properties and stimulate regenerative cellular processes. In vivo experiments have demonstrated that pristine dressings are superior in promoting collagen and fibroblast regeneration and accelerating cicatrization as compared to dressings containing natural products. The dressing embedded with hop also displayed antimicrobial characteristics. The preparation and testing of these new efficient wound dressings are described. This study is distinctive in its integration of environmentally conscious manufacturing techniques with innovative material formulations, resulting in superior wound dressings that are both cost‐effective and highly functional. By achieving enhanced healing and infection prevention without the employment of conventional antibiotics, this work represents a substantial advancement in sustainable and effective wound care management. [ABSTRACT FROM AUTHOR]

The aim of the study was to investigate the effect of ethanol on the properties of acrylic-urethane resin products obtained by vat photopolymerization using the masked stereolithography method. The effect of alcohol at concentrations of 15, 25, and 35% in the resin on the chemical structure, weight, thickness of the samples, and mechanical properties in static tabltensile tests performed immediately after printing and one month later were studied. The results obtained were evaluated in terms of the use of ethanol as a cosolvent to help load the resin with agomelatine for the potential of obtaining microneedle transdermal systems. It was shown that in terms of stability of properties, the most favorable system was resin with the addition of alcohol at a concentration of 15%. The greatest changes induced by the presence of the solvent in the resin were observed in the case of tensile properties, where the alcohol caused a decrease in the plasticity of the material, reducing the relative elongation at break from 14% for the pure resin to 4% when the alcohol concentration was 35%. Young's modulus and tensile strength also decreased with the addition of alcohol by 18% and 31%, respectively, for testable samples with the maximum amount of alcohol in the resin. The deterioration in properties is most likely related to the effect of the solvent on the radical polymerization process of the resin, particularly the phenomenon of chain transfer to the solvent, which is important in view of the intended application of the developed material. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to address the challenge of reducing the build time of a fused deposition modeling (FDM) system while maintaining part strength, proposing a hybrid technique combining photopolymerization and FDM. Design/methodology/approach: For developing the hybrid system, a standard FDM machine was modified to incorporate necessary components so that the whole system can be operated with a single interface; further, the samples were fabricated with conventional and modified process to evaluate the efficacy of the developed system, to determine the extent of time reduction that the proposed methodology can obtain, additionally different sort of 3D models were selected and their build time was compared. Findings: The modified hybrid mechanism can successfully fabricate parts with a modified G-code. The simulation of the technique shows that a reduction of 34%–87% can be achieved for simpler models such as cube while a reduction ranging from 30.6%–87.8% was observed for complex models. An increase in strength of 6.58%, 11.51% and 37.32% was observed in X, Y and Z directions, along with a significant increase in toughness as compared with FDM parts for parts fabricated with the developed mechanism. Practical implications: The modified mechanism could be used for fast fabrication purposes, which could be very useful for serving situations such as emergency health care, rapid tooling. Originality/value: This research contributes a novel hybrid technique for additive manufacturing, offering a substantial reduction in build time without compromising mechanical properties, even increasing them. [ABSTRACT FROM AUTHOR]

Radiation curing is an excellent option for the economical implementation of coatings while simultaneously producing technically advanced products. Nevertheless, the number of materials used is mainly limited to pure (meth)acrylate and epoxy systems. Polyisocyanurates could be an excellent addition to this range, especially due to their thermal and chemical stability. In this work, through the use of a transition metal‐based photocatalyst, as well as the use of 1,5‐diazabicyclo(4.3.0)non‐5‐en as a co‐catalyst, formulations are presented, which enable pure polyisocyanurates to be used in radiation‐based coating technology. Trimerization with this system using any primary isocyanates worked and consequently thus opened the possibility for aromatic and aliphatic polyisocyanurates. Using monofunctional isocyanates, the theoretical background of trimerization as well as the theoretical enthalpy is evaluated and the possibilities as well as the limitations for poly‐trimerization of polyisocyanurates are analyzed. Finally, photo‐induced catalytic poly‐trimerization of aliphatic isocyanates is used to obtain samples with a Tg in the range of 100 °C and onset of degradation above 400 °C. Thus, for the first time, a framework for the use of isocyanates in the field of photopolymerization and, in particular, in the field of radiation‐based coating of polyisocyanurates is provided for further development. [ABSTRACT FROM AUTHOR]

We report on concomitant photoinitiated polymerization‐induced macrophase and microphase separation strategies to produce hierarchically structured recyclable poly(n‐butyl acrylate) based elastomeric materials. The investigated crosslinker‐free formulations are composed of n‐butyl acrylate monomer and a UV photo‐initiator mixed with poly(methyl methacrylate)‐b‐poly(n‐butyl acrylate)‐poly(methyl methacrylate) ABA triblock copolymers. Two different pre‐synthesized copolymers are used to control the macrophase separation. One synthesized by nitroxide‐mediated radical polymerization (NMRP), and a second by anionic polymerization (AP). Essentially, NMRP route leads to copolymer with unsaturated chain ends, activated during UV photopolymerization. On the other hand, the copolymer synthesized by AP are chemically inert. That dissimilarity is also highlighted by time‐resolved FTIR and SAXS, performed to monitor respectively monomer conversion and nanostructure evolution during photopolymerization. The experimental data demonstrate that the reactivity of the triblock copolymer impacts drastically the polymerization kinetics and the self‐assembly processes. Finally, the rheological analysis shows that the produced materials present a solid‐like behavior at low frequencies despite a large PnBA content (i.e., 85 wt%). This property is associated to the phase segregation and to the sample hierarchical morphology. [ABSTRACT FROM AUTHOR]

The greater transparency of the polymer obtained by adding a small amount of molecular iodine to the liquid photopolymerizing composition is satisfactorily explained by the formation of a π,σ-type charge transfer (CT) complex of oligocarbonate dimethacrylate with molecular iodine. The CT band at 360 nm absorbs a significant part of the actinic radiation such that the rate of the photolytic decomposition of the photoinitiator in the initial polymerization stage permits release of free volume from the polymer into the liquid part of the photopolymerizing composite. Layer-by-layer photopolymerization occurs at advanced stages due to the thin upper layers exposed to UV irradiation becoming steadily more transparent. [ABSTRACT FROM AUTHOR]

The effects of salt water exposure at deep ocean depth pressures when coupled with low temperatures on the material characteristics of three unique additively manufactured polymers has been investigated through a detailed experimental approach. The polymers in the study were manufactured utilizing both Vat Photopolymerization and Material Extrusion printing techniques. The Material Extrusion process was utilized to produce material specimens of Stratasys ULTEM 9085 and Markforged Onyx while the Vat Photopolymerization process was used to produce specimens of Accura ClearVue. The ULTEM 9085 and Markforged Onyx are filament based polymers and the ClearVue is a liquid based resin. The specimens were first submerged in a high pressure, salt water bath of 3.5% NaCl solution at 34.5 MPa (5000 lb/in²) for a total exposure time of 60 days to determine the water absorption characteristics. Subsequent to the salt water exposure at high pressure, the specimens were evaluated to determine changes in tension, compression, flexure, and in-plane fracture properties. To determine the effects of water saturation and low temperature coupling, the mechanical testing was performed at temperatures of 20 °C, 0 °C and -20 °C in both dry and saturated conditions. Additionally, non-destructive testing in the form of TeraHertz and FIRT imaging was conducted to analyze the physical material changes through the thickness of the material due to the saline water absorption. To quantify the change in material storage and loss moduli properties, Dynamic Mechanical Analysis (DMA) characterization was performed on each of the AM polymers in dry and saturated states. The DMA testing also quantified changes in the Glass Transition Temperature because of salt water exposure. In summary, The current study investigates the effects of coupled long term/high pressure salt water exposure with low temperatures on the mechanical and material characteristics of three unique AM polymers by: (1) immersing the materials in a salt water solution at 34.5 MPa for 60 days, (2) Conducting post exposure mechanical testing on the materials at 0 °C and -20 °C with comparisons to 20 °C testing on dry specimens, and quantifies changes in material properties through DMA experiments. The results from all testing in the study show that high pressure salt water exposure when coupled with low temperatures has unique effects on each of the materials considered in the study and careful consideration to each parameter must be given based on the material type when components will be employed in marine operations. [ABSTRACT FROM AUTHOR]

The use of photopolymerization is expanding across a multitude of biomedical applications, from drug delivery to bioprinting. Many of these current and emerging photopolymerization systems employ visible light, as motivated by safety and energy efficiency considerations. However, the "library" of visible light initiators is limited compared with the wealth of options available for UV polymerization. Furthermore, the synthesis of traditional photoinitiators relies on diminishing raw materials, and several traditional photoinitiators are considered emerging environmental contaminants. As such, there has been recent focus on identifying and characterizing biologically sourced, visible light‐based photoinitiator systems that can be effectively used in photopolymerization applications. In this regard, several bio‐sourced molecules have been shown to act as photoinitiators, primarily through Type II photoinitiation mechanisms. However, whether bio‐sourced molecules can also act as effective synergists in these reactions remains unknown. In this study, we evaluated the effectiveness of bio‐sourced synergist candidates, with a focus on amino acids, due to their amine functional groups, in combination with two bio‐sourced photoinitiator molecules: riboflavin and curcumin. We tested the effectiveness of these photoinitiator systems under both violet (405 nm) and blue (460–475 nm) light using photo‐rheology. We found that several synergist candidates, namely lysine, arginine, and histidine, increased the polymerization effectiveness of riboflavin when used with both violet and blue light. With curcumin, we found that almost all tested synergist candidates slightly decreased the polymerization effectiveness compared with curcumin alone under both light sources. These results show that bio‐sourced molecules have the potential to be used as synergists with bio‐sourced photoinitiators in visible light photopolymerization. However, more work must be done to fully characterize these reactions and to investigate more synergist candidates. Ultimately, this information is expected to expand the range of available visible light‐based photoinitiator systems and increase their sustainability. [ABSTRACT FROM AUTHOR]

Benzophenone and its derivatives are widely used as UV filters and UV‐ink photoinitiators. The photoinitiating properties of benzophenones depend on their degree of conjugation and delocalization within the molecule. By understanding how conjugation, delocalization, and different substituents affect these properties, benzophenone derivatives can be customized for specific applications. Using quantum mechanical calculations based on B3LYP/6‐311++G(d, p) density functional theory (DFT), chemical reactivity, stability, and photoinitiating capabilities of 4‐(4‐methylphenylthio)benzophenone are analyzed. This includes studying its physical and chemical properties in the gas phase, as well as its excited state electronic transitions, vibrational characteristics, and spectroscopic properties both in gas phase and in various solvents. The DFT‐computed infrared spectra match experimental results. The UV/Visible spectra shows absorption towards longer wavelengths due to extended delocalization of π‐electrons. In different solvents with varying polarity, the absorption spectra exhibit high‐intensity peaks, shift in excitation energy and wavelengths based on the polarity of the solvent. This knowledge allows for the development of novel initiators with customized light absorption, excited state lifetimes, and reaction selectivities, which can enhance processes like UV‐curing, photopolymerization, and other light‐driven reactions. [ABSTRACT FROM AUTHOR]

Contact lenses are widely used for vision correction and cosmetic purposes. Smart contact lenses offer further opportunities as functionalized non-invasive devices capable of simultaneous vision correction, real-time health monitoring and patient specific drug delivery. Herein, a low-cost vat photopolymerization technique is developed for directly 3D printing functionalized structures on commercially available contact lenses. The process enables controlled deposition of functionalized hydrogels, in customizable patterns, on the commercial contact lens surface with negligible optical losses. Multi-functional contact lenses can also be 3D printed with multiple materials deposited at different regions of the contact lens. Herein, the functionalities of colour blindness correction and real-time UV monitoring are demonstrated, by employing three suitable dyes incorporated into 2-hydroxyethyl methacrylate (HEMA) hydrogel structures printed on contact lenses. The results suggest that 3D printing can pave the way towards simple production of low-cost patient specific smart contact lenses. [ABSTRACT FROM AUTHOR]

Alumina (Al2O3) ceramics are widely used in electronics, machinery, healthcare, and other fields due to their excellent hardness and high temperature stability. However, their high brittleness limits further applications, such as artificial ceramic implants and highly flexible protective gear. To address the limitations of single-phase toughening in Al2O3 ceramics, some researchers have introduced a second phase to enhance these ceramics. However, introducing a single phase still limits the range of performance improvement. Therefore, this study explores the printing of Al2O3 ceramics by adding two different phases. Additionally, a new gradient printing technique is proposed to overcome the limitations of single material homogeneity, such as uniform performance and the presence of large residual stresses. Unlike traditional vat photopolymerization printing technology, this study stands out by generating green bodies with varying second-phase particle ratios across different layers. This study investigated the effects of different contents of sepiolite fiber (SF) and 316L stainless steel (SS) on various aspects of microstructure, phase composition, physical properties, and mechanical properties of gradient-printed Al2O3. The experimental results demonstrate that compared to Al2O3 parts without added SF and 316L SS, the inclusion of these materials can significantly reduce porosity and water absorption, resulting in a denser structure. In addition, the substantial improvements, with an increase of 394.4% in flexural strength and an increase of 316.7% in toughness, of the Al2O3 components enhanced by incorporating SF and 316L SS have been obtained. [ABSTRACT FROM AUTHOR]

Light‐mediated 3D printing techniques have gained significant interest due to the inherent advantages of light as external stimuli, including spatiotemporal control and easy access. As 3D printing processes require rapid polymerization, free radical or cationic polymerization methods are used. However, these polymerization reactions are limited to the production of materials with properties that cannot be chemically altered post‐printing. In this work, a rapid, open‐to‐air photo‐controlled cationic reversible addition‐fragmentation chain‐transfer polymerization of vinyl ethers is demonstrated in the presence of a three‐component photoinitiating system comprising a photosensitizer, electron donor, and acceptor as co‐initiators under the irradiation with blue light. The polymerization mechanism shows rapid kinetics and controlled, living polymerization characteristics. Trithiocarbonate chain ends of poly(isobutyl vinyl ethers) are reactivated to produce block copolymers with cyclohexyl vinyl ethers. The rapid kinetics and water tolerance of the reported system enable the 3D printing of polymeric solids under ambient (e.g., room temperature and open to air) conditions, followed by the effective reactivation of trithiocarbonate chain ends to post‐synthetically modify the object with an acrylate‐based fluorescent monomer via a controlled radical polymerization strategy. [ABSTRACT FROM AUTHOR]

Nowadays, photopolymerization has spanned across all academic and industrial applications due to its appealing features such as energy saving, environmentally‐friendly polymerization conditions, high monomer conversions, rapid polymerization kinetics and so on. Photoinitiator (PI), as a crucial component of the photoinitiating system (PIS) are capable of interacting with light efficiently, enabling to generate initiating species in mono or multicomponent systems. In this work, 13 phenothiazine‐based oxime esters (OXEs) (never reported before) were synthesized and their photoinitiation abilities for the free radical photopolymerization (FRP) of acrylates were examined upon irradiation with LED@405 nm. Parallel to their photochemical reactivities, their abilities to initiate thermal polymerization processes were also investigated. Finally, these OXEs exhibited excellent photo/thermal initiation performances, demonstrating their dual initiation properties. Phenothiazine‐based oxime esters can be used as PIs in 3D printing as well as thermal initiator in the manufacturing of carbon fiber composites. [ABSTRACT FROM AUTHOR]

The additive manufacturing (AM) industry increasingly looks to differentiate itself by utilizing materials and processes that are green, clean, and sustainable. Biopolymers, bio‐sourced raw materials and light weighting of parts 3D printed with photopolymer resins each represent critical directions for the future of AM. Here, we report a series of bio‐based composite resins with soybean oil derivatives, up to 20% by weight of surface‐methacrylated micro‐crystalline cellulose (MCC) and 60% total bio‐based content for vat photopolymerization based additive manufacturing. The ultimate tensile strengths of the materials were found to increase up to 3X, the Young's moduli increased up to 10X, and the glass transition temperature increased by 11.3°C when compared to the neat resin without surface‐methacrylated MCC as a filler. Working curves and shrinkage factors were used to demonstrate how the surface‐methacrylated MCC causes changes in the dimensions of printed parts, to facilitate development of optimized print parameters based on the UV intensity of the 3D printer being used. These results will allow further development of commercial 3D printable resins with a high concentration of bio‐based fillers that print well and perform on par with conventional resins. [ABSTRACT FROM AUTHOR]

Stimuli‐responsive materials have recently gained significant attention in the field of soft robotics, sensors, and biomimetic devices. The most facile way for the fabrication of such materials remains to endow bilayer structures which are fabricated with the combination of active and passive layers. Although, easily fabricated, these structures suffer from the generation of stress points between connection areas. In this work we develop a method to create a thin film with controlled cross‐link variation across its thickness. The cross‐link gradient is achieved through polymerization induced diffusion of dithiol molecules in thiol‐ene network. As a result, the film exhibits bending deformation upon illumination with light or exposure to a chemical solvent, thereby demonstrating dual responsiveness. Light actuation of the film is achieved via photothermal effects due to the incorporation of dye into the system which can absorb UV light and heat the network. While solvent induced actuation is due to anisotropic swelling. Furthermore, the straightforward fabrication procedure allows for the creation of more complex deformations by patterning the film using a photomask during photopolymerization. [ABSTRACT FROM AUTHOR]

4D printing has emerged as a powerful strategy capable of revolutionizing additive manufacturing by enabling objects to dynamically transform overtime on demand. Despite significant progress, the full potential remains unrealized, particularly in the utilization of dynamic covalent chemistry. This study introduces a new approach using a multifunctional cross‐linker with alkoxyamine functionalities for 4D printing. Digital light processing (DLP) is employed for high‐resolution printing of complex objects. Leveraging alkoxyamine bonds' dynamic and living characteristics, the printed structures can be further modified through nitroxide‐mediated polymerization (NMP) using styrene and nitroxide exchange reactions (NER). The resulting "living" printed structures exhibit the unique ability to undergo both "growth" and "degrowth", dynamically adapting their size as well as the reduced Young's Modulus across a wide range (770 kPa–1.2 GPa). The chain extension by NMP and softening by NER are carefully characterized by IR and EPR spectroscopy. The presented approach opens avenues for the development of 4D printed structures with complex adaptive systems, showcasing enormous potential in a wide range of fields. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) of copper through laser‐based processes poses challenges, primarily attributed to the high thermal conductivity and low laser absorptivity of copper powder or wire as the feedstock. Although the use of copper salts in vat photopolymerization‐based AM techniques has garnered recent attention, achieving micro‐architected copper with high conductivity and density has remained elusive. In this study, we present a facile and efficient process to create complex 3D micro‐architected copper structures with superior electrical conductivity and hardness. The process entails the formulation of an ion‐exchangeable photoresin, followed by the utilization of digital light processing (DLP) printing to sculpt 3D hydrogel scaffolds, which were transformed into Cu2+‐chelated polymer frameworks (Cu‐CPFs) with a high loading of Cu2+ ions through ion exchange, followed by debinding and sintering, results in the transformation of Cu‐CPFs into miniaturized copper architectures. This methodology represents an efficient pathway for the creation of intricate micro‐architected 3D metal structures. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) of copper through laser‐based processes poses challenges, primarily attributed to the high thermal conductivity and low laser absorptivity of copper powder or wire as the feedstock. Although the use of copper salts in vat photopolymerization‐based AM techniques has garnered recent attention, achieving micro‐architected copper with high conductivity and density has remained elusive. In this study, we present a facile and efficient process to create complex 3D micro‐architected copper structures with superior electrical conductivity and hardness. The process entails the formulation of an ion‐exchangeable photoresin, followed by the utilization of digital light processing (DLP) printing to sculpt 3D hydrogel scaffolds, which were transformed into Cu2+‐chelated polymer frameworks (Cu‐CPFs) with a high loading of Cu2+ ions through ion exchange, followed by debinding and sintering, results in the transformation of Cu‐CPFs into miniaturized copper architectures. This methodology represents an efficient pathway for the creation of intricate micro‐architected 3D metal structures. [ABSTRACT FROM AUTHOR]