Photosensitive Resin Research Articles

Superaerophobic polymer objects prototyped via liquid crystal display (LCD)-based 3D printing: one-step post-surface-treatment and application in underwater bubble manipulation

ABSTRACT Underwater superaerophobic surface is of great significance for controllable manipulation of gas bubbles in scientific research and practical applications. However, the fabrication of arbitrary-shaped superaerophobic solid surfaces through a simple and low-cost approach is still hard. Herein, superaerophobic 3D objects were manufactured via liquid crystal display (LCD)-based 3D printing (vat photopolymerisation-based additive manufacturing) combined with one-step post-surface-treatment in sodium hydroxide (NaOH) solution. The influences of NaOH concentration, reaction temperature and time on the wettability of the polymer surface were systematically investigated. After a suitable alkali-treatment, the object surface obtained a bubble contact angle of 159° with extremely low bubble adhesion, featuring the underwater superaerophobicity. Morphology and composition characterisation demonstrated that a hydrophilic gel layer was produced on the printed sheet after the alkali-treatment, which is explained as the main mechanism of the superwetting transition from aerophobicity to superaerophobicity. Interestingly, spontaneously formed surface microgrids (size in xy direction: ∼50 μm) during 3D printing accelerated the alkali-treatment. Further, a superaerophobic 3D tweezer was designed, fabricated, and successfully applied in a toxic nitric oxide (NO) bubble reaction underwater for gas purity detection. The one-step post-surface-treatment method is also suitable for other commercial photosensitive resins and digital-light-processing (DLP) 3D printing.

Mechanically robust, highly toughened, corrosion and impact resistant epoxy/silica nanocomposites by UV curing 3D printing technology

In this paper, a photosensitive resin was successfully synthesized using epoxy as a matrix and the effect of nanosilica on its properties was investigated. Micromorphology analyses show that the nanosilica has good dispersion and strong interaction with the matrix. Additionally, a finite element model was developed to predict the tensile performance of the nanocomposite under high-strain loads. Molecular dynamics simulations demonstrated a favorable binding energy between nanosilica and epoxy resin. The effects of nanosilica on the fracture toughness and energy release rate of photosensitive resins were investigated using load-enhanced tensile test method. The results showed that the addition of 1.0 wt.% nanosilica particles increased the toughness of the resin from 0.45 MPa m1/2 to 0.79 MPa m1/2, and the energy release rate from 248.3 J/m2 to 555.7 J/m2; compared with the neat photosensitive resins, the incorporation of nanosilica increased the tensile and impact strengths of the resins by 26.8% and 49.2%, respectively. The nanosilica was used to improve the tensile strength and impact strength of the resin by 26.8% and 49.2% respectively compared with the neat photosensitive resin. Electrochemical corrosion analysis showed that the photosensitive resin/nanosilica composites have excellent corrosion resistance. Under different corrosion environments of acid, alkali, and salt, the addition of 1 wt.% nanosilica in the photosensitive resin composite led to an increase in corrosion voltage by 0.023 V, 0.004 V, and 0.1 V respectively compared to neat photosensitive resin. Additionally, the corrosion current density decreased by 1.39 × 10−6 A/cm2, 0.525 × 10−4 A/cm2, and 2.57 × 10−6 A/cm2, respectively. On this basis, the independently synthesised photosensitive resin has excellent strength and 0.01 mm printing accuracy.

Fabrication of ZrO2 Armor Ceramics by 3D Printing Accompanied with Microwave Sintering

Ceramic armor protection with complex shapes is limited by the difficult molding or machining processing, and 3D printing technology provides a feasible method for complex-shaped ceramics. In this study, ZrO2 ceramics were manufactured by 3D printing accompanied with microwave sintering. In 3D printing, the formula of photosensitive resin was optimized by controlling the content of polyurethane acrylic (PUA) as oligomer, and the photosensitive resin with 50% PUA showed excellent curing performance with a small volume shrinkage of 4.05%, media viscosity of 550 mPa·s, and low critical exposure of 20 mJ/cm2. Compared to conventional sintering, microwave sintering was beneficial to dense microstructures with fine grain size, and microwave sintering at 1500 °C was confirmed as an optimized sintering process for the 3D-printed ZrO2 ceramics, and the obtained ceramics showed a relative density of 98.2% and mean grain size of 2.1 μm. The PUA content further affected the microstructure and mechanical property of the ZrO2 ceramics. The sample with 10%~40% PUA showed some pores due to the low viscosity and large volume shrinkage of photosensitive resins, and the sample with 60% PUA exhibited an inhomogeneous microstructure with agglomeration, attributed to the high viscosity of photosensitive resins. Finally, the ZrO2 ceramics via 3D printing with 50% PUA showed superior mechanical properties, whose Vickers hardness was 3.4 GPa, fracture toughness was 7.4 MPa·m1/2, flexure strength was 1038 MPa, and dynamic strength at 1200 s−1 was 4.9 GPa, conducive to the material’s employment as armor protection ceramics.

Safety and efficacy of a 3D-printed external cranial protection device in preventing complications after unilateral supratentorial decompressive craniectomy: A retrospective cohort study.

The objective was to clarify the feasibility and clinical effect of 3D-printed external cranial protection devices (ECPD) in preventing complications following unilateral supratentorial decompressive craniectomy (DC). A retrospective cohort study was conducted on post-DC patients meeting inclusion and exclusion criteria. In the experimental group, head computed tomography data were collected after DC, and the ECPD were 3D-printed with photosensitive resin materials, and fixed to the bone window defect for continuous wear. The control group received similar postoperative treatment and procedures but did not place the ECPD. Clinical data were collected and analyzed. Forty-four patients were enrolled, 24 in the experimental and 20 in the control group. The incidence of postoperative complications of DC was 84.09%. The median time to initial use of the 3D-printed ECPD was 13.5 days. No patients had skin pressure ulcers, allergies, or wound infections. There were no statistically significant differences between the groups in pre-DC Glasgow Coma Scale scores, post-DC complication rates, or Glasgow Outcome Scale scores at discharge (P > .05). Whereas, there was a statistically significant difference in pre-cranioplasty DC-related complications (P = .027), with a notable reduction in the incidence of subdural effusion in the experimental group (P = .004). The 2 groups had no significant differences in modified Rankin Scale scores after cranioplasty. The clinical use of the 3D-printed ECPD is safe and reliable, effectively reducing the incidence of complications following DC, particularly in the prevention and treatment of subdural effusion. However, it does not significantly improve the prognosis of patients after DC, warranting further research.

Isobornyl acrylate‐based photosensitive resins for high-resolution digital light processing 3D printing of garnet ceramics

Isobornyl acrylate‐based photosensitive resins for high-resolution digital light processing 3D printing of garnet ceramics

A universal strategy to design recyclable photocrosslinked networks via architecting lignin-derived spiro diacetal trigger

Precise transformation of renewable resources into high-performance photo-crosslinked resins with degradability remains a daunting challenge. In this work, we employed a renewable bioresource, lignin-derived vanillin, to construct a rigid spiro diacetal trigger, which was further coupled with thermosetting epoxy segments to develop three high-performance functionalized polymers. Several high-performance photosensitive materials with alkali-dissolving patterning and recyclable were innovatively engineered based on these polymers. The introduction of rigid spiro diacetal triggers, which function through a unique degradable mechanism under mildly acidic conditions, is expected to address the “seesaw” issue between high performance and degradability in photo-crosslinked networks. More importantly, the effect of spiro diacetal trigger on the thermo-mechanical properties and photopolymerization kinetics of thus-obtained photosensitive resins was systematically investigated. Consequently, the glass transition temperature and mechanical properties of the spiro diacetal-tailored naphthalene-type photosensitive resin (P-VPNE) are comparable to, or even exceed, those of competing materials. This work provides a universal strategy and valuable insights for the design and synthesis of high-performance degradable electronic packaging coatings, which are essential for a wide range of revolutionary technologies based on lignin derivatives.

Development of Soft Wrinkled Micropatterns on the Surface of 3D-Printed Hydrogel-Based Scaffolds via High-Resolution Digital Light Processing.

The preparation of sophisticated hierarchically structured and cytocompatible hydrogel scaffolds is presented. For this purpose, a photosensitive resin was developed, printability was evaluated, and the optimal conditions for 3D printing were investigated. The design and fabrication by additive manufacturing of tailor-made porous scaffolds were combined with the formation of surface wrinkled micropatterns. This enabled the combination of micrometer-sized channels (100-200 microns) with microstructured wrinkled surfaces (1-3 μm wavelength). The internal pore structure was found to play a critical role in the mechanical properties. More precisely, the TPMS structure with a zero local curvature appears to be an excellent candidate for maintaining its mechanical resistance to compression stress, thus retaining its structural integrity upon large uniaxial deformations up to 70%. Finally, the washing conditions selected enabled us to produce noncytotoxic materials, as evidenced by experiments using AlamarBlue to follow the metabolic activity of the cells.

Near-infrared nonlinear WLEDs with high stability through atomic-level regulation and photosensitive resin encapsulating by 3D printing

Upconversion luminescence (UCL) is a nonlinear opticalphenomenon where long wavelength radiation is converted to shorter wavelength via a two-photon or multi-photon mechanism. The construction of near-infrared nonlinear WLEDs can achieve effective utilization of sunlight. This work starts with "functional Motifs" and regulates the nonlinear luminescent materials at the molecular level by combining DFT calculations and high-throughput techniques. As expected, the optimized geometric structures, band structures, and density of states of Ba2YbF7:Ln3+ were successfully obtained by assembling [BaBr4] and [LnBr4] functional Motifs. Subsequently, Ba2YbF7:Ln3+ single phosphor was prepared and further encapsulated into resin to achieve highly stable upconversion white light using 3D printing technology. After being placed for 8 months, the luminescence intensity and spectral shape of the resin coated sample remain unchanged. The color coordinates of the WLED device constructed with Ba2YbF7:Tm3+/Er3+ single fluorescent powder is (0.3086, 0.3163) and the related color temperature (CCT) is 6863 K. The optimized material has a maximum color rendering index of 83. This work provides new insights and ideas for improving the luminescence stability of upconversion WLED using 3D printing technology.

Inverse Rendering for Tomographic Volumetric Additive Manufacturing

Tomographic Volumetric Additive Manufacturing (TVAM) is an emerging 3D printing technology that can create complex objects in under a minute. The key idea is to project intense light patterns onto a rotating vial of photo-sensitive resin, causing polymerization where the cumulative dose of these patterns reaches the polymerization threshold. We formulate the pattern calculation as an inverse light transport problem and solve it via physically based differentiable rendering. In doing so, we address longstanding limitations of prior work by accurately modeling and correcting for scattering in composite resins, printing in non-symmetric vials, and supporting unusual printing geometries. We also introduce an improved discretization scheme that exploits the ray tracing operation to mitigate resolution-related artifacts in prints. We demonstrate the benefits of our method in real-world experiments, where our computed patterns produce prints with an improved fidelity.

Numerical simulation model for the curing of photosensitive acrylate resin in a stereolithography process

Numerical simulation model for the curing of photosensitive acrylate resin in a stereolithography process

A combined stereolithography and a pressureless sintering method to prepare SiC ceramics

The use of submicron silicon carbide powder as a raw material is crucial for preparing high-performance silicon carbide ceramics. However, its strong absorption of ultraviolet light makes stereolithography of submicron silicon carbide powder challenging. In this study, submicron SiC particles, photosensitive resin, and photoinitiator were used as raw materials to prepare SiC ceramics via stereolithography combined with a pressureless sintering method. The effects of ultraviolet wavelength, type, and content of photoinitiator on the curing properties of submicron SiC ceramic slurry were investigated. The results showed that the curing thickness of the SiC ceramic slurry significantly increased with the increasing ultraviolet wavelength. Compared to photoinitiators TPO and 396, photoinitiator 819 exhibited a better curing effect. Additionally, increasing the photoinitiator content facilitated the generation of more free radicals in the SiC ceramic slurry at low light intensity, thereby improving its ultraviolet absorption characteristics. When the dosage of photoinitiator 819 was 8.8 %, the SiC slurry achieved the best curing performance, with a single-layer curing thickness of 50 μm and a sintering density of 95 % for SiC ceramics.

Formula Design of Hyperbranched Polyarylether‐Based Low Dielectric Photosensitive Resin and Study of UV‐Cured Films Properties

ABSTRACTFor large‐area electronic and high shape complexity structure applications, various solution‐processable materials are chosen as dielectric layer due to their simple molding process via spin‐coating, casting, or 3D printing at room temperature. Herein, the acrylic‐ended fluorinated hyperbranched polyaryletherketone (hb‐P6FAEK‐Ace) was used as the prepolymer and then, the composition of photosensitive resin formula was regulated by adjusting the addition ratio of hb‐P6FAEK‐Ace and diluents (acrylimorpholine [ACMO] 1,6‐Hexanediol diacrylate [HDDA]). These photosensitive resin solutions showed the relative low viscosities ranged ranging from 18 to 253 mPa S at 100°C which was in favor of the future 3D printing method and printing accuracy. Then, the obtained UV‐cured films show the maximum tensile strength up to 71.9 MPa and superior thermal properties with the Tg of 157°C–177°C and T5% of 314°C–351°C. Moreover, they also exhibited the good dielectric performance with dielectric constants of 2.43–2.20 and dielectric loss of 0.013–0.014 at 1 MHz–1 GHz. These abovementioned satisfactory performance could be ascribed to the aromatic skeleton of hb‐P6FAEK‐Ace, introduced polarizability‐CF3 groups and the inner cavities for the hyperbranched structures, also the precise control of formula composition. Additionally, the curing degree, shrinkage of solid, and moisture properties were also researched thoroughly. This work provides a simple formula design though to construct the high performance and low dielectric photosensitive resin for the requirements of microelectronic applications.

Shape-programmable hard-magnetic soft actuators with high magnetic particle content via digital light processing method

In this work, we developed a novel hard-magnetic photosensitive suspension with high solid loadings of 50 wt% for digital light processing 3D printing. The suspension combining photosensitive resin and reactive diluent can retain stability for 6 h. The printed materials from the suspension achieve a low modulus of below 900 kPa and high remanence of 83.7 kA/m. The suspension’s cure behavior was studied in detail to obtain the optimal printing parameters. The printing error of the small structures with feature size of about 1000 μm is kept below 20 %. Moreover, we proposed an efficient magnetization programming strategy for hard-magnetic soft actuators with desirable shapes based on the rod model considering the non-magnetic load. The accuracy and reliability of the strategy are verified by the experiment results. Finally, we designed and fabricated a “flower” using our method, achieving its closing action in accordance with the prescribed shape.

Development and mechanical properties of nano SiO2 modified photosensitive resin for high-strength and high-brittleness 3D printing in rock reconstruction

3D printing technology, as a rapid prototyping method, can accurately reconstruct the internal structural characteristics of samples, making it highly promising for rock engineering applications. However, current 3D printing materials used to reconstruct rocks suffer from low strength and high ductility, which is inconsistent with the high strength and brittleness of natural rocks. This paper explores the use of silane coupling agents KH550 (γ-aminopropyl triethoxysilane) and KH570 (γ-methacryloxypropyl trimethoxysilane) to modify nano SiO2 powder. Through sample preparation and uniaxial compression tests, the mechanical properties and failure characteristics of the modified nano SiO2 powder were analyzed. The results indicate that, using the preparation method with a mass ratio of E-44 epoxy resin, KH550 modified nano SiO2 powder, and 593 curing agent at 80:40:26, the samples achieved an uniaxial compressive strength of up to 30.55 MPa without enhanced brittle post-processing. The failure characteristics exhibited significant axial tensile damage. Additionally, combining CT scanning technology demonstrated that the structural and mechanical properties of the samples can be effectively reproduced. Therefore, the 3D printing materials discussed in this paper provide a viable reference for accurately reconstructing high-strength and high-brittleness rock masses.

Preparation of magnetothermal Fe3O4/MgO/HA composite scaffolds for cancer hyperthermia by Vat Photopolymerization

Bone defects resulting from bone tumor resections are often complicated with residual cancer cells. To address the challenge, the magnetothermal porous structured bone scaffolds of hydroxyapatite-Fe3O4-MgO (HA-FM) were fabricated by Vat Photopolymerization (VPP). This study improved curing behavior by doping Mg(OH)2 into Fe3O4 powder via the chemical deposition method. Mg(OH)2 functioned as a pore-forming agent during the sintering process, decomposing into MgO to enhance biocompatibility. A two-step debinding method combined with a carbon powder embedding sintering process was used employed to resolve the conflict between the removal of photosensitive resin and the oxidation of Fe3O4. After sintering at 1200°C, the porosity of the composite ceramics reached 69 % and a compressive strength of 2.28 MPa. In vitro mineralization tests showed that doping with Fe3O4 and Mg(OH)2 could promote the scaffolds’ degradation in simulated body fluid (SBF), beneficial to mineralization process. In vitro cell proliferation and adhesion experiments showed that ceramic samples were not cytotoxic and could promote osteogenic differentiation. The composite scaffolds exhibited magnetothermal properties, achieving a temperature increase of 8.2°C in the alternating magnetic field of 92 G and 100 kHz, indicating potential for cancer treatment.

Fe2O3, Al2O3, or sludge ash-catalyzed pyrolysis of typical 3D printing waste toward tackling plastic pollution

Catalytic pyrolysis offers a potential solution to tackling plastic pollution by transforming plastic waste into valuable chemicals. This study explored the catalytic pyrolysis of 3D printing waste (3DPW), specifically focusing on photosensitive resin waste (PRW) and polycaprolactone waste (PCLW), with Al2O3, Fe2O3, or sludge ash (SA) containing Fe/Al. The study revealed a synergistic effect between the catalyst and 3DPW, influencing the pyrolysis properties and kinetic models. The addition of Fe2O3 significantly accelerated the main degradation stages, promoting the releases of 2-Ethylacrolein (64.78 % from PRW) and 2-Oxepanone (16.45 % from PCLW), as well as decreasing the acidic products. The catalytic pyrolysis changed the valence state of Fe, with some Fe(III) shifting to Fe(II), accompanied by the release of CO2. The addition of Al2O3 or SA generated new gaseous products (e.g., 2.93 % 1,3-Pentadiene, 2-methyl-, (E)-) through volatile reforming. The joint optimization of the multi-response artificial neural network revealed PCLW/Fe2O3 between 325–399 °C (D = 0.669) as the optimal operation for achieving both minimal remaining mass and maximum decomposition rate. These findings offer actionable insights into the catalytic pyrolysis of 3DPW, promoting its efficient treatment and clean reutilization.

Characterization of SLA-printed ceramic composites for dental restorations

This study introduces a novel ceramic-composite resin specifically developed for stereolithography (SLA) 3D printing, aimed at enhancing dental restorations. The integration of advanced digital technologies in dentistry has shifted traditional methods towards more precise and efficient techniques such as computer-aided design/computer-aided manufacturing (CAD/CAM). However, these processes typically involve material waste due to their subtractive nature. Additive manufacturing, or 3D printing, particularly SLA, which uses ultraviolet light to cure photosensitive resins, presents a viable alternative with the potential for creating detailed, custom restorations with minimal waste. Our research focuses on formulating and evaluating a ceramic-composite resin that combines the benefits of light-cured materials with the mechanical robustness required for dental applications. We conducted comprehensive tests to assess the printability, mechanical properties and wear resistance of the developed material. The ceramic-composite resin demonstrated a tensile strength of approximately 73 MPa, significantly higher than the 42 MPa observed for traditional photopolymer resins. Additionally, the ceramic-composite resin showed ability to resist incidental friction and wear. This research could significantly impact the dental prosthetics field by providing a method for producing high-performance, patient-specific restorations efficiently and cost-effectively.

SonoPrint: Acoustically Assisted Volumetric 3D Printing for Composites.

Advances in additive manufacturing in composites have transformed aerospace, medical devices, tissue engineering, and electronics. A key aspect of enhancing properties of 3D-printed objects involves fine-tuning the material by embedding and orienting reinforcement within the structure. Existing methods for orienting these reinforcements are limited by pattern types, alignment, and particle characteristics. Acoustics offers a versatile method to control the particles independent of their size, geometry, and charge, enabling intricate pattern formations. However, integrating acoustics into 3D printing has been challenging due to the scattering of the acoustic field between polymerized layers and unpolymerized resin, resulting in unwanted patterns. To address this challenge, SonoPrint, an innovative acoustically assisted volumetric 3D printer is developed that enables simultaneous reinforcement patterning and printing of the entire structure. SonoPrint generates mechanically tunable composite geometries by embedding reinforcement particles, such as microscopic glass, metal, and polystyrene, within the fabricated structure. This printer employs a standing wave field to create targeted particle motifs-including parallel lines, radial lines, circles, rhombuses, hexagons, and polygons-directly in the photosensitive resin, completing the print in just a few minutes. SonoPrint enhances structural properties and promises to advance volumetric printing, unlocking applications in tissue engineering, biohybrid robots, and composite fabrication.

Water-based metamaterial absorber for temperature modulation

In this study, a transmissive all-dielectric metamaterial absorber comprising a photosensitive resin and water layers was proposed. The water layers comprised coin rings, crosses, and fan shapes. The as-obtained absorber achieved >90% absorption of electromagnetic waves within the frequency range of 18.4–41.7 GHz, and the absorption bandwidth covered the Ka-band. Because of the symmetric structure of the designed metamaterial, it was not influenced by polarization. The inherent dispersive properties of water result in a dielectric constant that varies significantly with temperature. This led to fluctuations in the absorption efficiency of the designed metamaterial to different degrees with changes in temperature. The analysis of electric and magnetic fields distributions revealed that the primary absorption physical mechanism of the designed metamaterial originated from magnetic resonances in the water layers. The proposed transmissive metamaterial absorber has potential applications in high-sensitivity thermal and temperature sensors.

Dimension compensation of printed master molds by a desktop LCD 3D printer for high-precision microfluidic applications.

Recent advances in low-cost liquid crystal display (LCD) 3D printing have popularized its use in creating microfluidic master molds and complete devices. However, the quality and precision of these fabrications often fall short of the rigorous standards required for advanced microfluidic applications. This study introduces a novel approach to enhance the dimensional accuracy of microchannels produced using a desktop LCD 3D printer. We propose a method for dimension compensation, optimize the printing parameters, and provide a straightforward post-treatment technique to ensure high-quality curing of polydimethylsiloxane (PDMS) in master molds made from photosensitive resin. Our investigation assesses the precision of 3D printing across three different scales of square cross-section microchannels by measuring their widths and heights, leading to the determination of optimal printing parameters that minimize dimensional errors. The dimensional errors are further reduced by introducing a series of dimension compensation factors, which correct the nominal dimensions of the microchannels by using the compensation factors in 3D printing. The dimensional accuracy is significantly improved after compensation even in fabricating complex microchannels of triangular cross-sections. Finally, a spiral channel of trapezoidal-like cross-section with tilted edges is fabricated for microfluidic application, and highly efficient particle separation is realized in the channel. The proposed method provides new insights for utilizing desktop LCD 3D printers to achieve high-accuracy microstructures necessary for advanced microfluidic applications.