Search Results (123)

This study aimed to develop experimental filler-reinforced resin composites for vat-photopolymerization 3D printing and to evaluate the effects of filler addition on their mechanical, physicochemical, and bonding properties for dental restorative applications. Silanized nano- and/or micro-fillers were incorporated into acrylic resin monomers to formulate photocurable resins suitable for vat-photopolymerization. The rheological behavior of these liquid-state resins was assessed through viscosity measurements. Printed resin composites were fabricated and characterized for mechanical properties—including flexural strength, flexural modulus, and Vickers hardness—both before and after 8 weeks of water immersion. Physicochemical properties, such as water sorption, water solubility, and degree of conversion, were also evaluated. Additionally, shear bond strength to a resin-based luting agent was measured before and after artificial aging via thermocycling. A commercial dental CAD-CAM resin composite served as a reference material. Filler incorporation significantly improved the mechanical properties of the printed composites. The highest performance was observed in the composite containing 60 wt% micro-fillers, with a flexural strength of 168 ± 10 MPa, flexural modulus of 6.3 ± 0.4 GPa, and Vickers hardness of 63 ± 1 VHN, while the commercial CAD-CAM composite showed values of 152 ± 8 MPa, 7.9 ± 0.3 GPa, and 66 ± 2 VHN, respectively. Filler addition did not adversely affect the degree of conversion, although the relatively low conversion led to the elution of unpolymerized monomers and increased water solubility. The shear bond strength of the optimal printed composite remained stable after aging without silanization, demonstrating superior bonding performance compared with the CAD-CAM composite. These findings suggest that the developed 3D-printed resin composite is a promising candidate for dental restorative materials. Full article

Photocuring, including photopolymerization and photocrosslinking, has emerged as a transformative manufacturing paradigm that enables the precise, rapid, and customizable fabrication of advanced battery components. This review first introduces the principles of photocuring and vat photopolymerization and their unique advantages of high process efficiency, non-contact fabrication, ambient-temperature processing, and robust interlayer bonding. It then systematically summarizes photocured battery components, involving electrolytes, membranes, anodes, and cathodes, highlighting their design strategies. This review examines the impact of photocured materials on the battery’s properties, such as its conductivity, lithium-ion transference number, and mechanical strength, while examining how vat-photopolymerization-derived 3D architectures optimize ion transport and electrode–electrolyte integration. Finally, it discusses current challenges and future directions for photocuring-based battery manufacturing, emphasizing the need for specialized energy storage resins and scalable processes to bridge lab-scale innovations with industrial applications. Full article

We report the fabrication of lightweight porous carbon structures via UV-assisted photopolymerization molding using a commercial photocurable resin modified with natural tannin and sodium carboxymethyl cellulose (NaCMC) as sustainable additives. A systematic analysis was conducted by applying a Design of Experiments (DOE) approach and regression modeling to evaluate the effects of varying blend compositions on carbon yield and mechanical strength. The results indicate that increasing the tannin content led to a maximum carbon yield of 13.43%, with an average porosity of approximately 80% and a compressive strength around 1 kPa. NaCMC was found to effectively control the resin viscosity within printable limits of 0.2537 Pa·s, although NaCMC indirectly improved carbonization efficiency through normalized yield analysis. This work highlights the synergistic role of bio-based polymers in tuning porous carbon properties. The findings provide a data-driven framework for designing sustainable polymer-derived carbon materials, bridging additive manufacturing with green chemistry. Full article

Purpose: The aim of this in vitro study was to evaluate the influence of different models of commercially available portable dental radiometers on the measurement of light irradiance emitted by light-emitting diode (LED) photocuring units. Materials and Methods: Eight LED photocuring units, all emitting light in a single-wavelength spectrum, were tested. Light irradiance (mW/cm²) was measured using six portable dental radiometers: four digital models (D1–D4) and two analog models (A1, A2). Digital model D1 was used as the reference (control). All measurements were conducted under standardized conditions, and each LED–radiometer combination was tested in triplicate. Data were analyzed using Sigma Plot 12.0 (Palo Alto, CA, USA) to verify the assumptions of normality and homogeneity of variances. A one-way analysis of variance (ANOVA) was used to assess the effect of the radiometer model on irradiance values, followed by Tukey’s post hoc test for multiple comparisons. The significance level was set at α < 0.05. Results: No statistically significant difference in irradiance was found between D1 (control) and D2. However, significantly lower values were recorded with A2, while D3, D4, and A1 produced significantly higher irradiance values compared to the control (p < 0.05). Conclusion: Irradiance measurements can vary significantly depending on the radiometer model used. Clinicians should be aware of this variability and are encouraged to regularly check the irradiance of the light-curing units used in daily practice, ensure their proper maintenance, and implement periodic monitoring to maintain effective clinical performance. Full article

Perfusable microvasculature is critical for advancing in vitro tissue models, particularly for neural applications where limited diffusion impairs organoid growth and fails to replicate neurovascular function. This study presents a versatile fabrication platform that integrates mesh-driven design, two-photon lithography (TPL), and modular interfacing to create multi-material, perfusable 3D microvasculatures. Various 2D and 3D capillary paths were test-printed using both polygonal and lattice support strategies. A double-layered capillary scaffold based on the Hilbert curve was used for comparative materials testing. Methods for printing rigid (OrmoComp), moderately stiff hydrogel (polyethylene glycol diacrylate, PEGDA 700), and soft elastomeric (photocurable polydimethylsiloxane, PDMS) materials were developed and evaluated. Cone support structures enabled high-fidelity printing of the softer materials. A compact heat-shrink tubing interface provided leak-free perfusion without bulky fittings. Physiologically relevant flow velocities and Dextran diffusion through the scaffold were successfully demonstrated. Cytocompatibility assays confirmed that all TPL-printed scaffold materials supported human neural stem cell viability. Among peripheral components, lids fabricated via fused deposition modeling designed to hold microfluidic needle adapters exhibited good biocompatibility, while those made using liquid crystal display-based photopolymerization showed significant cytotoxicity despite indirect exposure. Overall, this platform enables creation of multi-material microvascular systems facilitated by TPL technology for complex, 3D neurovascular modeling, blood–brain barrier studies, and integration into vascularized organ-on-chip applications. Full article

Ionizing radiations are responsible for bond scission, radical formation, and oxidative degradation of polymer matrices. This study focuses on the effects of gamma irradiation on solid propellant binders, targeting a comprehensive chemical and mechanical characterization of different formulations. Samples were produced either by conventional methods based on hydroxyl-terminated polybutadiene and standard polyaddition reaction using isocyanates, or innovative approaches involving UV-driven radical curing. The samples were irradiated for comparison and to study their evolution as a function of three absorbed doses (25, 45, 130 kGy) for preliminary characterization studies, using a 60-Co gamma source. Samples were irradiated in air at uncontrolled room temperature. The coupling of spectroscopy techniques (Fourier transform infrared—FTIR, Raman and electron paramagnetic resonance—EPR) and dynamic mechanical analysis (DMA) highlighted the key role of antioxidant agents in tailoring mechanical changes in the binder phase. The absence of antioxidants enhances radical formation, oxidation, and cross-linking. These processes lead to progressively increased rigidity and reduced flexibility as a function of the absorbed dose. Complex interactions between photocured components largely influence radical stabilization and material degradation. These findings provide valuable insights for designing novel radiation-resistant binders, enabling the development of solid propellants tailored for reliable, long-term permanence in space, and advancing the knowledge on the applicability of 3D-printed propellants. Full article

This study explores the synthesis of photocurable non-isocyanate polyhydroxyethylurethanes (BPHUs) derived from renewable sources, designed for biomedical applications and the development towards advanced light curing processes. The following two pathways were developed: an aliphatic route using 1,4-butanediol-derived cyclic carbonates and an aromatic route with resorcinol-based carbonates. Ring-opening polymerization with dodecanediamine produced BPHU intermediates, which were methacrylated to form photoreactive derivatives (aliphatic MAs and aromatic MAs). Comprehensive characterization, including NMR, GPC, and FTIR, confirmed the successful synthesis. The UV curing of these methacrylated compounds yielded hydrogels with swelling properties. Aliphatic BPHUs achieved a gel content of 91.3% and a swelling of 1057%, demonstrating the flexibility and UV stability suitable for adaptable biomedical applications. Conversely, aromatic BPHUs displayed a gel content of 78.1% and a swelling of 3304%, indicating higher rigidity, which is advantageous for load-bearing uses. Cytotoxicity assessments adhering to the DIN EN ISO 10993-5 standard demonstrated non-cytotoxicity, with an >80% cell viability for both variants. This research underscores the potential of green chemistry in crafting biocompatible, versatile BPHUs, paving the way for eco-friendly materials in implantable medical devices. Full article

Thiol–epoxy photopolymerization offers exceptional advantages for high-performance protective coatings, yet efficiently curing thick formulations remains a significant challenge due to the limited penetration depth of conventional UV light. Herein, we report a novel near-infrared (NIR) light-activated photopolymerization system for deep-curing applications, strategically integrating upconversion nanoparticles (UCNPs) as NIR-to-UV converters, isopropylthioxanthone (ITX) as a photosensitizer, and a liquid N-phenylglycine-based photobase generator (NPG-TBD) with enhanced resin solubility. Upon 980 nm NIR irradiation, photogenerated TBD efficiently catalyzes thiol–epoxy polymerization through an anionic mechanism, enabling uniform network formation with epoxy and thiol functional group conversions greater than 90% throughout samples exceeding 2.5 cm in thickness. The resulting coatings exhibit excellent mechanical properties including 3H pencil hardness, strong adhesion (0 grade), and good flexibility (2 mm), significantly outperforming conventional UV systems limited to approximately 1.5 mm. Additionally, the cured materials demonstrate multifunctional characteristics including distinctive upconversion luminescence and dual-responsive shape memory behavior. This approach addresses critical limitations in deep-photocuring technology while offering significant potential for applications in protective coatings for marine infrastructure, chemical storage facilities, and smart materials requiring both substantial barrier properties and programmable responsiveness. Full article

W-Cu composites are widely used in the fields of switch contact materials and electronic packages because of their high hardness, high plasticity, and excellent thermal conductivity, while the traditional W-Cu composite preparation process is often accompanied by problems such as a long production cycle, difficulties in the processing of shaped parts, and difficulties in guaranteeing the uniformity. Therefore, this work developed a chemical plating technique to prepare W-20 wt.% Cu composite powder with a core–shell structure and used this powder as a raw material for powder metallurgy to solve the problem of inhomogeneity in the production of W-Cu composite by the conventional solution infiltration method. Moreover, the work also developed a high-temperature-resistant photosensitive resin, which was used as a raw material to prepare injection molds using photocuring to replace traditional steel molds. Compared to steel molds, which take about a month to prepare, 3D printed plastic molds take only a few hours, greatly reducing the production cycle. At the same time, 3D printing also provides the feasibility of the production of shaped parts. The injection molded blanks were degreased and sintered under different sintering conditions. The results show that the resultant chemically plated W-Cu composite powder has a uniform Cu coating on the surface, and the Cu forms a dense and uniform three-dimensional network in the scanning electron microscope images of each subsequent sintered specimen, while the photocuring-prepared molds were used to prepare the W-Cu shaped parts, which greatly shortened the production cycle. This preparation method enables rapid preparation of tungsten–copper composite-shaped parts with good homogeneity. Full article

This study presents a sustainable approach to transform waste cooking oil (WCO) into a multifunctional 3D-printable photocurable elastomer with integrated self-healing capabilities. A linear monomer, WCO-based methacrylate fatty acid ethyl ester (WMFAEE), was synthesized via a sequential strategy of transesterification, epoxidation, and ring-opening esterification. By copolymerizing WMFAEE with hydroxypropyl acrylate (HPA), a novel photocurable elastomer was developed, which could be amenable to molding using an LCD light-curing 3D printer. The resulting WMFAEE-HPA elastomer exhibits exceptional mechanical flexibility (elongation at break: 645.09%) and autonomous room-temperature self-healing properties, achieving 57.82% recovery of elongation after 24 h at 25 °C. Furthermore, the material demonstrates weldability (19.97% retained elongation after 12 h at 80 °C) and physical reprocessability (7.75% elongation retention after initial reprocessing). Additional functionalities include pressure-sensitive adhesion (interfacial toughness: 70.06 J/m² on glass), thermally triggered shape memory behavior (fixed at −25 °C with reversible deformation/recovery at ambient conditions), and notable biodegradability (13.25% mass loss after 45-day soil burial). Molecular simulations reveal that the unique structure of the WMFAEE monomer enables a dual mechanism of autonomous self-healing at room temperature without external stimuli: chain diffusion and entanglement-driven gap closure, followed by hydrogen bond-mediated network reorganization. Furthermore, the synergy between monomer chain diffusion/entanglement and dynamic hydrogen bond reorganization allows the WMFAEE-HPA system to achieve a balance of multifunctional integration. Moreover, the integration of these multifunctional attributes highlights the potential of this WCO-derived photocurable elastomer for various possible 3D printing applications, such as flexible electronics, adaptive robotics, environmentally benign adhesives, and so on. It also establishes a paradigm for converting low-cost biowastes into high-performance smart materials through precision molecular engineering. Full article

This study analyzed the use of cork-derived biochar, obtained through pyrolysis, as a more sustainable additive than traditional carbon materials. In addition, the present study explored its application in a polymer matrix through additive manufacturing via stereolithography. To the best of our knowledge, this approach has not been reported in scientific literature. The cork biochar retained the morphology of the original cork and integrated well into the photocurable polymer, as demonstrated by scanning electron microscopy. This integration can contribute to the formation of internal networks within the material, potentially modifying some of its properties. At specific low percentages, cork biochar enhanced both the electrical conductivity and mechanical properties of photocurable polymers. Notably, the required biochar concentrations were minimal, facilitating its incorporation into the photopolymer matrix. Additionally, the thermal stability of the material slightly improved at certain percentages but remained comparable to that of the original polymer in all cases. These findings highlight the potential of cork biochar as a sustainable additive for advanced polymer composites. Full article

The long-term success of bone implant scaffolds depends on numerous factors, such as their porosity, mechanical properties, and biocompatibility. These properties depend on the type of material, such as metals and their alloys or ceramics, and the procedure used to create the scaffolds. This study aims to find the biomimetic properties of aluminum 6061 (Al 6061) alloy through Digital Light Processing (DLP) and sintering. Hollow cylindrical Al 6061 samples are printed through the DLP process at 90, 110, and 130 Wt.% aluminum powder concentrations inside a photocurable resin. The ideal temperature at which the material is sintered is 550 °C for 130 and 110 Wt.% and 530 °C for 90 Wt.%. The overall pore size ranges in the Al 6061 of these three concentrations from 30 μm to 700 μm. The compression test revealed the materials’ Ultimate Tensile Strengths (UTSs) to be 1.72, 2.2, and 1.78 MPa for the 90, 110, and 130 Wt.% materials, respectively. A simulation of the Al 6061 material as linear isotropic resulted in the UTS being 2.2 MPa. This novel hybrid of the additive manufacturing method and sintering created a scaffold model with anisotropic properties closer to trabecular bone, which could be used to observe fracture progression and could be tested for implant capabilities. Full article

Material Jetting (MJT) 3D printing (3DP) is a specific technology that deposits photocurable droplets of material and colored inks to fabricate objects layer-by-layer. The high resolution and full color capability render MJT 3DP an ideal technology for 3DP in medicine as evidenced by the 3DP literature. The technology has been adopted globally across the Americas, Europe, Asia, and Australia. While MJT 3D printers can be expensive, their ability to fabricate highly accurate and multi-color parts provides a lucrative opportunity in the creation of advanced prototypes and medical models. The literature on MJT 3DP has expanded greatly as of late, in part aided by the lowering costs of the technology, and this report is the first review to document the applications of MJT in medicine. Additionally, this report portrays the technological information behind MJT 3DP, cases involving fabricated MJT 3DP models from the University of Cincinnati 3DP lab, as well as the challenges of MJT in a clinical setting, including cost, expertise in managing the machines, and scalability issues. It is expected that MJT 3DP, as imaging and segmentation technologies undergo future improvement, will be best poised with representing the voxel-level-variations captured by radiologic-image-sets due to its capacity for voxel-level-control. Full article

Four kinds of silicone hydrogel transparent contact lenses (CLs) with different formulations were prepared by the free radical photocuring polymerization. By mixing polyethylene glycol diacrylate (PEGDA) of 1000 Da with ethylene glycol dimethacrylate (EGDMA) and adding other silicone monomers and hydrophilic monomers, the transparency and flexibility of the material were successfully achieved. By optimizing the weight percentage of each component, the best balance of optical performance can be achieved. The photocuring properties of the materials were characterized by electronic universal test, double-beam UV-visible spectrophotometer, Atomic Force Microscope (AFM), Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). The results showed that the addition of higher PEGDA content reduces the elastic modulus, improves curing efficiency, improves equilibrium water content (EWC), and enhances light transmission. Hydrogels containing only high PEGDA but no EGDMA showed similar curing rates, water content, and elastic modulus, but had the worst optical transparency, far inferior to the materials mixed with PEGDA and EGDMA. Additionally, imaging performance of the CLs was further evaluated through simulation analysis using Ansys Zemax OpticStudio2024 software. This research provides a new choice of material consideration to improve the performance and wearing comfort of CLs. Full article

The printing precision of hydrogels directly determines the mechanical and electrical performance of scaffolds. In this study, poly(3,4-ethylenedioxythiophene)-poly (styrenesulfonate) (PEDOT:PSS) was directly compounded with glycidyl methacrylate-modified silk fibroin (Sil-MA) through a one-pot method to increase the solid content of the printing ink, enhancing its mechanical, electrical, and printability properties. A dual-network photo-curable conductive silk fibroin composite hydrogel (CDMA) was successfully prepared. The results show that the introduction of PEDOT:PSS significantly improved the conductivity of the hydrogel. (The bandgap decreased from 2.36 eV to 1.125 eV, and the maximum conductivity reached 0.534 S/m.) It also enhanced the microscopic 3D network density and mechanical properties of the hydrogel (compressive modulus up to 192 kPa). Moreover, the hydrogel demonstrated good stability during cyclic stability testing, providing a new approach to developing materials capable of high-precision printing with stable electrical performance. Full article