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Green Synthesis of Soybean Oil-Derived UV-Curable Resins for High-Resolution 3D Printing
... In contrast, materials with higher D p (>1.0 mm), such as some soybean oil-based resins (e.g., AESO [42]), might exhibit substantial Z-axis deviations (>5% error at 50 µm layer thickness) due to uncontrolled light penetration, rendering them unsuitable for intricate geometries (Table 1). While higher D p may theoretically enable faster printing via thicker layers, this advantage is offset by the need for stringent light-source calibration to mitigate over-curing artifacts, as demonstrated in prior studies [43,44]. Notably, the A4 elastomer's D p (0.224 mm) was lower than some commercial resin (D p = 0.314 mm [45]), achieving enhanced compatibility with high-resolution printing. ...
... tricate geometries (Table 1). While higher Dp may theoretically enable faster printing via thicker layers, this advantage is offset by the need for stringent light-source calibration to mitigate over-curing artifacts, as demonstrated in prior studies [43,44]. ...
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.
Materials derived from natural sources are demanded for future applications due to the combination of factors such as sustainability increase and legislature requirements. The availability and efficient analysis of vegetable oils (triacylglycerides) open an enormous potential for incorporating these compounds into various products to ensure the ecological footprint decreases and to provide advantageous properties to the eventual products, such as flexibility, toughness, or exceptional hydrophobic character. The double bonds located in many vegetable oils are centers for chemical functionalization, such as epoxidization, hydroxylation, or many nucleophile substitutions using acids or anhydrides. Naturally occurring castor oil comprises a reactive vacant hydroxyl group, which can be modified via numerous chemical approaches. This comprehensive Review provides an overall insight toward multiple materials utilities for functionalized glycerides such as additive manufacturing (3D printing), polyurethane materials (including their chemical recycling), coatings, and adhesives. This work provides a complex list of investigated and studied applications throughout the available literature and describes the chemical principles for each selected application.
The additive manufacturing of photopolymer resins by means of vat photopolymerization enables the rapid fabrication of bespoke 3D-printed parts. Advances in methodology have continually improved resolution and manufacturing speed, yet both the process design and resin technology have remained largely consistent since its inception in the 1980s¹. Liquid resin formulations, which are composed of reactive monomers and/or oligomers containing (meth)acrylates and epoxides, rapidly photopolymerize to create crosslinked polymer networks on exposure to a light stimulus in the presence of a photoinitiator². These resin components are mostly obtained from petroleum feedstocks, although recent progress has been made through the derivatization of renewable biomass3–6 and the introduction of hydrolytically degradable bonds7–9. However, the resulting materials are still akin to conventional crosslinked rubbers and thermosets, thus limiting the recyclability of printed parts. At present, no existing photopolymer resin can be depolymerized and directly re-used in a circular, closed-loop pathway. Here we describe a photopolymer resin platform derived entirely from renewable lipoates that can be 3D-printed into high-resolution parts, efficiently deconstructed and subsequently reprinted in a circular manner. Previous inefficiencies with methods using internal dynamic covalent bonds10–17 to recycle and reprint 3D-printed photopolymers are resolved by exchanging conventional (meth)acrylates for dynamic cyclic disulfide species in lipoates. The lipoate resin platform is highly modular, whereby the composition and network architecture can be tuned to access printed materials with varied thermal and mechanical properties that are comparable to several commercial acrylic resins.
Four-dimensional (4D) printing, combining three-dimensional (3D) printing with time-dependent stimuli-responsive shape transformation, eliminates the limitations of the conventional 3D printing technique for the fabrication of complex hollow constructs. However, existing...
The general requirement of replacing petroleum-derived plastics with renewable resources is particularly challenging for new technologies such as the additive manufacturing of photocurable resins. In this work, the influence of mono- and bifunctional reactive diluents on the printability and performance of resins based on acrylated epoxidized soybean oil (AESO) was explored. Polyethylene glycol di(meth)acrylates of different molecular weights were selected as diluents based on the viscosity and mechanical properties of their binary mixtures with AESO. Ternary mixtures containing 60% AESO, polyethylene glycol diacrylate (PEGDA) and polyethyleneglycol dimethacrylate (PEG200DMA) further improved the mechanical properties, water resistance and printability of the resin. Specifically, the terpolymer AESO/PEG575/PEG200DMA 60/20/20 (wt.%) improved the modulus (16% increase), tensile strength (63% increase) and %deformation at the break (21% increase), with respect to pure AESO. The enhancement of the printability provided by the reactive diluents was proven by Jacobs working curves and the improved accuracy of printed patterns. The proposed formulation, with a biorenewable carbon content of 67%, can be used as the matrix of innovative resins with unrestricted applicability in the electronics and biomedical fields. However, much effort must be done to increase the array of bio-based raw materials.
The design of lignin nanostructures where interfacial interactions enable enhanced entanglement of colloidal networks can broaden their applications in hydrogel‐based materials and light‐based 3D printing. Herein, an approach for fabricating surface‐active dendritic colloidal microparticles (DCMs) characterized by fibrous structures using nanostructured allylated lignin is proposed for the development of lignin‐based photocurable resins. With allyl‐terminated surface functionality of 0.61 mmol g⁻¹, the entanglement between lignin‐DCM fibrils with a size of 1.4 µm successfully produces only lignin‐based hydrogels with structural integrity through photo‐crosslinking. The colloidal network of lignin dendricolloids reinforces the poly(ethylene glycol) (PEG) hydrogels during a digital light processing (DLP) 3D printing process by generating bicontinuous morphologies, resulting in six‐fold increases in toughness values with respect to the neat PEG hydrogel. The dual effectiveness of photoabsorption and free‐radical reactivity of lignin‐DCMs allow the light‐patterning of rather dilute PEG hydrogels (5–10%) with high geometric fidelity and structural complexity via DLP 3D printing. This study demonstrates a green and effective strategy for the design of 1D lignin‐DCMs that increases the versatility of the nanostructured biopolymer, opening up numerous opportunities for formulating functional hydrogels with robust structure‐property correlations.
The rapid advancement in the miniaturization, integration, and intelligence of electronic devices has escalated the demand for customizable micro‐supercapacitors (MSCs) with high energy density. However, efficient microfabrication of safe and high‐energy MXene MSCs for integrating microelectronics remains a significant challenge due to the low voltage window in aqueous electrolytes (typically ≤0.6 V) and limited areal mass loading of MXene microelectrodes. Here, we tackle these challenges by developing a high‐concentration (18 mol kg⁻¹) “water‐in‐LiBr” (WiB) gel electrolyte for MXene symmetric MSCs (M‐SMSCs), demonstrating a record high voltage window of 1.8 V. Subsequently, additive‐free aqueous MXene ink with excellent rheological behavior is developed for three‐dimensional (3D) printing customizable all‐MXene microelectrodes on various substrates. Leveraging the synergy of a high‐voltage WiB gel electrolyte and 3D‐printed microelectrodes, quasi‐solid‐state M‐SMSCs operating stably at 1.8 V are constructed, and achieve an ultrahigh areal energy density of 1772 μWh cm⁻² and excellent low‐temperature tolerance, with a long‐term operation at −40°C. Finally, by extending the 3D printing protocol, M‐SMSCs are integrated with humidity sensors on a single planar substrate, demonstrating their reliability in miniaturized integrated microsystems.
4D printing technology combines 3D printing and stimulus-responsive materials, enabling construction of complex 3D objects efficiently. However, unlike smart soft materials, 4D printing of ceramics is a great challenge due to the extremely weak deformability of ceramics. Here, we report a feasible and efficient manufacturing and design approach to realize direct 4D printing of ceramics. Photocurable ceramic elastomer slurry and hydrogel precursor are developed for the fabrication of hydrogel-ceramic laminates via multimaterial digital light processing 3D printing. Flat patterned laminates evolve into complex 3D structures driven by hydrogel dehydration, and then turn into pure ceramics after sintering. Considering the dehydration-induced deformation and sintering-induced shape retraction, we develop a theoretical model to calculate the curvatures of bent laminate and sintered ceramic part. Then, we build a design flow for direct 4D printing of various complex ceramic objects. This approach opens a new avenue for the development of ceramic 4D printing technology.
Three-dimensional (3D) microprinting is considered a next-generation manufacturing process for the production of microscale components; however, the narrow range of suitable materials, which include mainly polymers, is a critical issue that limits the application of this process to functional inorganic materials. Herein, we develop a generalised microscale 3D printing method for the production of purely inorganic nanocrystal-based porous materials. Our process is designed to solidify all-inorganic nanocrystals via immediate dispersibility control and surface linking-induced interconnection in the nonsolvent linker bath and thereby creates multibranched gel networks. The process works with various inorganic materials, including metals, semiconductors, magnets, oxides, and multi-materials, not requiring organic binders or stereolithographic equipment. Filaments with a diameter of sub-10 μm are printed into designed complex 3D microarchitectures, which exhibit full nanocrystal functionality and high specific surface areas as well as hierarchical porous structures. This approach provides the platform technology for designing functional inorganics-based porous materials.
The importance of bioink suitability for extrusion bioprinting tissue‐like constructs cannot be overemphasized. Owing to their excellent accessibility, alginate (Alg) ‐based bioinks are widely used. However, the printability accuracy and post‐printing stability of current Alg‐based bioinks remain challenging, especially for large‐size fabrication. Herein, an improvement strategy for pre‐crosslinking and post‐crosslinking of methacrylated Alg (AlgMA) bioinks in extrusion bioprinting is presented via introduction of methacrylated ɛ‐polylysine (ɛ‐PLMA) as a small‐molecule polycationic crosslinker. Due to their electrostatic interaction and covalent bonding, ɛ‐PLMA significantly reinforce the operability and prolong stability of AlgMA bioinks, in comparison with single‐molecule Ca²⁺ or large‐molecule methacrylated gelatin as pre‐crosslinkers. Meanwhile, attributed to their regulation of a charged microenvironment (−345.25 to 121.55 mV) and hydrophilicity (26.64° to 52.00°), the cells in bioprinted AlgMA/PLMA constructs demonstrated improved viability and vitality. Therefore, such a strategy of introducing small‐molecule cationic crosslinker ɛ‐PLMA is a promising booster for improving Alg‐based extrusion bioprinting, potential to extend its biomedical applications.
Microgels that assemble upon issuing of a trigger open up miscellaneous applications in soft robotics, drug delivery, and life‐like materials, due to their unique physical and chemical properties. In this work, a novel hydrogel photoresist system is formulated, consisting of 2‐hydroxyethyl acrylate, ethylene glycol diacrylate, and phenyl bis(2,4,6‐trimethylbenzoyl) phosphine oxide, as well as redox‐sensitive supramolecular host‐guest association motifs. Complex and multi‐compartmented geometries with precisely located recognition motifs are printed in high resolution, resulting in multifunctional structured microgel building blocks for mesoscopic self‐assembly. An enzymatic feedback system is employed to dissipatively assemble and disassemble the redox‐active microgel building blocks in a temporally and spatially controlled pathway. The self‐assembling photoresist system is characterized in terms of the lower critical solution temperature, swelling behavior, and printability. The present work provides new perspectives for the design of tailor‐made mesoscopic microgels with customizable functionality and high applicability for various technological applications.
Blood vessels are essential for nutrient and oxygen delivery and waste removal. Scaffold-repairing materials with functional vascular networks are widely used in bone tissue engineering. Additive manufacturing is a manufacturing technology that creates three-dimensional solids by stacking substances layer by layer, mainly including but not limited to 3D printing, but also 4D printing, 5D printing and 6D printing. It can be effectively combined with vascularization to meet the needs of vascularized tissue scaffolds by precisely tuning the mechanical structure and biological properties of smart vascular scaffolds. Herein, the development of neovascularization to vascularization to bone tissue engineering is systematically discussed in terms of the importance of vascularization to the tissue. Additionally, the research progress and future prospects of vascularized 3D printed scaffold materials are highlighted and presented in four categories: functional vascularized 3D printed scaffolds, cell-based vascularized 3D printed scaffolds, vascularized 3D printed scaffolds loaded with specific carriers and bionic vascularized 3D printed scaffolds. Finally, a brief review of vascularized additive manufacturing-tissue scaffolds in related tissues such as the vascular tissue engineering, cardiovascular system, skeletal muscle, soft tissue and a discussion of the challenges and development efforts leading to significant advances in intelligent vascularized tissue regeneration is presented.
Additive manufacturing technology has significantly impacted contemporary industries due to its ability to generate intricate computer-designed geometries. However, 3D-printed polymer parts often possess limited application potential, primarily because of their weak mechanical attributes. To overcome this drawback, this study formulates liquid crystal/photocurable resins suitable for the stereolithography technique by integrating 4’-pentyl-4-cyanobiphenyl with a photosensitive acrylic resin. This study demonstrates that stereolithography facilitates the precise modulation of the existing liquid crystal morphology within the resin. Furthermore, the orientation of the liquid crystal governs the oriented polymerization of monomers or prepolymers bearing acrylate groups. The products of this 3D printing approach manifest anisotropic behavior. Remarkably, when utilizing liquid crystal/photocurable resins, the resulting 3D-printed objects are approximately twice as robust as those created using commercial resins in terms of their tensile, flexural, and impact properties. This pioneering approach holds promise for realizing autonomously designed structures that remain elusive with present additive manufacturing techniques.
4D printing recently emerges as an exciting evolution of conventional 3D printing, where a printed construct can quickly transform in response to a specific stimulus to switch between a temporary variable state and an original state. In this work, a photocrosslinkable polyethylene–glycol polyurethane ink is synthesized for light‐assisted 4D printing of smart materials. The molecular weight distribution of the ink monomers is tunable by adjusting the copolymerization reaction time. Digital light processing (DLP) technique is used to program a differential swelling response in the printed constructs after humidity variation. Bioactive microparticles are embedded into the ink and the improvement of biocompatibility of the printed constructs is demonstrated for tissue engineering applications. Cell studies reveal above 90% viability in 1 week and ≈50% biodegradability after 4 weeks. Self‐folding capillary scaffolds, dynamic grippers, and film actuators are made and activated in a humid environment. The approach offers a versatile platform for the fabrication of complex constructs. The ink can be used in tissue engineering and actuator applications, making the ink a promising avenue for future research.
The amalgamation of wearable technologies with physiochemical sensing capabilities promises to create powerful interpretive and predictive platforms for real-time health surveillance. However, the construction of such multimodal devices is difficult to be implemented wholly by traditional manufacturing techniques for at-home personalized applications. Here, we present a universal semisolid extrusion–based three-dimensional printing technology to fabricate an epifluidic elastic electronic skin (e ³ -skin) with high-performance multimodal physiochemical sensing capabilities. We demonstrate that the e ³ -skin can serve as a sustainable surveillance platform to capture the real-time physiological state of individuals during regular daily activities. We also show that by coupling the information collected from the e ³ -skin with machine learning, we were able to predict an individual’s degree of behavior impairments (i.e., reaction time and inhibitory control) after alcohol consumption. The e ³ -skin paves the path for future autonomous manufacturing of customizable wearable systems that will enable widespread utility for regular health monitoring and clinical applications.
Stretchable ionotronics have drawn increasing attention during the past decade, enabling myriad applications in engineering and biomedicine. However, existing ionotronic sensors suffer from limited sensing capabilities due to simple device structures and poor stability due to the leakage of ingredients. In this study, we rationally design and fabricate a plethora of architected leakage-free ionotronic sensors with multi-mode sensing capabilities, using DLP-based 3D printing and a polyelectrolyte elastomer. We synthesize a photo-polymerizable ionic monomer for the polyelectrolyte elastomer, which is stretchable, transparent, ionically conductive, thermally stable, and leakage-resistant. The printed sensors possess robust interfaces and extraordinary long-term stability. The multi-material 3D printing allows high flexibility in structural design, enabling the sensing of tension, compression, shear, and torsion, with on-demand tailorable sensitivities through elaborate programming of device architectures. Furthermore, we fabricate integrated ionotronic sensors that can perceive different mechanical stimuli simultaneously without mutual signal interferences. We demonstrate a sensing kit consisting of four shear sensors and one compressive sensor, and connect it to a remote-control system that is programmed to wirelessly control the flight of a drone. Multi-material 3D printing of leakage-free polyelectrolyte elastomers paves new avenues for manufacturing stretchable ionotronics by resolving the deficiencies of stability and functionalities simultaneously.
Digital light processing (DLP) of structurally complex poly(ethylene glycol) (PEG) hydrogels with high mechanical toughness represents a long-standing challenge in the field of 3D printing. Here, we report a 3D printing approach for the high-resolution manufacturing of structurally complex and mechanically strong PEG hydrogels via heat-assisted DLP. Instead of using aqueous solutions of photo-crosslinkable monomers, PEG macromonomer melts were first printed in the absence of water, resulting in bulk PEG networks. Then, post-printing swelling of the printed networks was achieved in water, producing high-fidelity 3D hydrogels with complex structures. By employing a dual-macromonomer resin containing a PEG-based four-arm macrophotoinitiator, "all-PEG" hydrogel constructs were produced with compressive toughness up to 1.3 MJ m −3. By this approach, porous 3D hydrogel scaffolds with trabecular-like architecture were fabricated, and the scaffold surface supported cell attachment and the formation of a monolayer mimicking bone-lining cells. This study highlights the promises of heat-assisted DLP of PEG photopolymers for hydrogel fabrication, which may accelerate the development of 3D tissue-like constructs for regenerative medicine.
The application of wearable sensors in domains related to healthcare systems, human motion detection, robotics, and human–machine interactions has attracted significant attention. Because these applications require stretchable, flexible, and non-invasive materials, polymer composites are now at the forefront of research aimed at preparing innovative wearable sensors. Three-dimensional (3D) printing techniques can be used to obtain highly customised and scalable polymer composites to fabricate wearable sensors, which is a challenging task for conventional fabrication techniques. This review provides insights into the prospects of commonly used conductive nanomaterials and 3D printing techniques to prepare wearable devices. Subsequently, the research progress, sensing mechanisms, and performance of 3D-printed wearable sensors, such as strain, pressure, temperature, and humidity sensors, are discussed. In addition, novel 3D-printed multifunctional sensors, such as multi-directional, multi-modal, self-healable, self-powered, in situ printed, and ultrasonic sensors, are highlighted. The challenges and future trends for further research development are clarified.
A successful 3D printing of a novel 3D architected auxetic for large‐volume soft tissue engineering is reported. The 3D auxetic design is analyzed through finite element (FE) simulation and created by selective laser sintering (SLS) of Poly‐ε‐caprolactone (PCL) for further in‐depth mechanical and biological analysis. High initial flexibility and nonlinear stress–strain response to the uniaxial compression are achieved despite the use of PCL, which is one of the biomaterials that is clinically approved but has the disadvantage of having relatively stiff and linear mechanical properties. The high mass transport properties of the 3D auxetic are also demonstrated by not only high cell viability but also cell functionality within a cell‐laden hydrogel in large sizes of the auxetic. The outstanding mechanical and biological performance of the 3D auxetic is a consequence of the synergistic effect of the novel architected auxetic design combined with the inherent printing characteristic of SLS. The current study demonstrates great potential of SLS‐based printing of 3D auxetics toward the development of clinically viable 3D implants for the reconstruction of large‐volume soft tissues. The current study reports 3D printing of a novel architected auxetic with enhanced mechanical and biological performance. Specifically, printed auxetics have high flexibility, permeability, and nonlinear deformation behavior as demonstrated through computational, mechanical, and biological analysis. These characteristics provide a great potential to create clinically viable implants for the reconstruction of large‐volume soft tissues.
3D printing technologies and continuous flow microreaction systems are rapidly gaining attention in the domain of heterogeneous catalysis.
Digital Light Processing (DLP) allows the fast realization of 3D objects with high spatial resolution. However, DLP is limited to transparent resins, and therefore not well suited for printing electrically conductive materials. Manufacturing conductive materials will significantly broaden the spectrum of applications of the DLP technology. But conductive metals or carbon‐based fillers absorb and scatter light; inhibiting thereby photopolymerization, and lowering resolution. In this study, UV transparent liquid crystal graphene oxide (GO) is used as precursor for generating in situ conductive particles. The GO materials are added to a photopolymerizable resin via an original solvent exchange process. By contrast to earlier contributions, the absence of drying during the all process allows the GO material to be transferred as monolayers to limit UV scattering. The absence of UV scattering and absorption allows for fast and high‐resolution 3D printing. The chosen resin sustain high temperature to enable an in situ efficient thermal reduction of GO into reduced graphene oxide (rGO) that is electrically conductive. The rGO particles form percolated networks with conductivities up to 1.2 × 10⁻² S m⁻¹. The present method appears therefore as a way to reconcile the DLP technology with the manufacturing of 3D electrically conductive objects.
Three-dimensional (3D) bioprinting techniques have emerged as the most popular methods to fabricate 3D-engineered tissues; however, there are challenges in simultaneously satisfying the requirements of high cell density (HCD), high cell viability, and fine fabrication resolution. In particular, bioprinting resolution of digital light processing-based 3D bioprinting suffers with increasing bioink cell density due to light scattering. We developed a novel approach to mitigate this scattering-induced deterioration of bioprinting resolution. The inclusion of iodixanol in the bioink enables a 10-fold reduction in light scattering and a substantial improvement in fabrication resolution for bioinks with an HCD. Fifty-micrometer fabrication resolution was achieved for a bioink with 0.1 billion per milliliter cell density. To showcase the potential application in tissue/organ 3D bioprinting, HCD thick tissues with fine vascular networks were fabricated. The tissues were viable in a perfusion culture system, with endothelialization and angiogenesis observed after 14 days of culture.
Producing lightweight structures with high weight-specific strength and stiffness, self-healing abilities, and recyclability, is highly attractive for engineering applications such as aerospace, biomedical devices, and smart robots. Most self-healing polymer systems used to date for mechanical components lack 3D printability and satisfactory load-bearing capacity. Here, we report a new self-healable polymer composite for Digital Light Processing 3D Printing, by combining two monomers with distinct mechanical characteristics. It shows a desirable and superior combination of properties among 3D printable self-healing polymers, with tensile strength and elastic modulus up to 49 MPa and 810 MPa, respectively. Benefiting from dual dynamic bonds between the linear chains, a healing efficiency of above 80% is achieved after heating at a mild temperature of 60 °C without additional solvents. Printed objects are also endowed with multi-materials assembly and recycling capabilities, allowing robotic components to be easily reassembled or recycled after failure. Mechanical properties and deformation behaviour of printed composites and lattices can be tuned significantly to suit various practical applications by altering formulation. Lattice structures with three different architectures were printed and tested in compression: honeycomb, re-entrant, and chiral. They can regain their structural integrity and stiffness after damage, which is of great value for robotic applications. This study extends the performance space of composites, providing a pathway to design printable architected materials with simultaneous mechanical robustness/healability, efficient recoverability, and recyclability.
Using tung oil as the raw material, a new bio-based prepolymer was successfully synthesized by reacting with acrylic-modified rosin (β-acryloyl nutrient ethyl) ester (ARA)/acrylic-2-hydroxyethyl ester (HEA) followed by the use of the above composite material as the matrix and then reacting with the active diluent (2-HEMA, TPGDA) and the photoinitiator TPO and Irgacure1173 to successfully synthesize a new type of bio-based prepolymer-acrylate-epoxy tung oil polypolymer (AETP). The tung oil monomer before and after the epoxy formation was compared by proton NMR spectroscopy, and the chemical structure of AETP was analyzed by Fourier transform spectroscopy. Tung oil has an acid value of 1.5 mg KOH per g, an epoxy value of 5.38%, an iodine value of 11.28 g/100 g, and a refractive index of n 25 = 1.475. Composite-based 3D printing resins (like AETP) were cured using digital light treatment, while some samples were also post-treated via ultraviolet (UV) light treatment. The AETP-based 3D printing resin has excellent thermal and mechanical properties, and the viscosity of its system is 313 mPa s; exposure time 4.5 s; the tensile strength, flexural strength and flexural modulus were 62 MPA, 63.84 MPa and 916.708 MPa, respectively; Shore hardness was 80 HD and shrinkage was 4.00%. The good performance of the AETP-based 3D printing resin is attributed to the rigidity of their tightly crosslinked structure. This study pioneered a method for producing photoactive acrylates (e.g., tung oil-based acrylate oligomer resins) from renewable, low-cost biomass for light-curing 3D printing.
Processing tough hydrogels into sophisticated architectures is crucial for their applications as structural elements. However, digital light processing (DLP) printing of tough hydrogels is challenging because of the low‐speed gelation and toughening process. Described here is a simple yet versatile system suitable for DLP printing to form tough hydrogel architectures. The aqueous precursor consists of commercial photo‐initiator, acrylic acid, and zirconium ion (Zr4+), readily forming tough metallosupramolecular hydrogel under digital light because of in situ formation of carboxyl‐Zr4+ coordination complexes. The high stiffness and anti‐swelling property of as‐printed gel enable high‐efficiency printing to form high‐fidelity constructs. Furthermore, swelling‐induced morphing of the gel is also achieved by encoding structure gradients during the printing with grayscale digital light. Mechanical properties of the printed hydrogels are further improved after incubation in water due to the variation of local pH and rearrangement of coordination complex. The swelling‐enhanced stiffness affords the printed hydrogel with shape fixation ability after manual deformations, and thereby provides an additional avenue to form more complex configurations. These printed hydrogels are used to devise impact‐absorption element or high‐sensitivity pressure sensor as proof‐of‐concept examples. This work should merit engineering of other tough gels and extend their scope of applications in diverse fields. This article is protected by copyright. All rights reserved
The development of renewable green synthesis methods for polyamide materials is of great significance in the chemical industry. In this context, we present a synthesis and characterization of a novel...
Abstract
A polymeric ene-based thiol-ene network is reported that was demonstrated for light-based 3D printing. Allyl poly (acrylate ethyl lactate) (PAEL) was synthesized starting from ethyl lactate in an efficient and scalable manner. Ethyl lactate is a biobased material obtained naturally or chemically in high yields in the form of ethyl ester of lactic acid. Isosorbide, which is also a bio based resource was converted into thiol derivative and was used along with Pentaerythritol tetrakis(3-mercaptopropionate) (PETMP) as multifunctional thiol. The polymeric nature of the ene (i.e. PAEL) imparted exceptionally high mechanical properties like Young's modulus of 1.75 GPa as well as high thermal stability with a decomposition temperature (Td,10%) exceeding 350 °C for all the networks studied. The properties could also be customized by fine tuning the type and stoichiometric ratio of the thiol crosslinked employed. For instance, the Young's modulus range from 1.75 GPa to 1.03 GPa and glass transition temperature range from 44 °C to 54 °C could be achieved. DLP 3D printing was used to demonstrate the printability of the resins with high resolution and structural fidelity. The study also highlights the base-mediated rapid hydrolytic degradation efficiency of the 3D printed parts, demonstrating the applicability of these novel polymeric ene based thiol-ene for sustainable and eco-friendly 3D printable formulations.
The 3D-printed MXene electrodes hold great promise for the development of next-generation electrochemical devices, offering improved performance, customization, and design flexibility. To this end, it is crucial to improve the...
To serve the accessibility of polyimide aerogels (PAs) in diverse application scenarios, a major objective is to create PAs in dimension/or geometry on demand. However, the ability to deliver excellent...
Ultraviolet (UV)-curable coatings made from acrylated epoxy soybean oil (AESO) combine the advantages of renewable biobased resources and energy-efficient UV-curable materials, so they serve as the primary research objects for developing eco-friendly coatings. However, due to the lack of rigid structure, the hardness and thermal stability of AESO are much lower than those of petroleum-based epoxy acrylate (EA). Therefore, high-performance soybean oil-based UV-curable oligomers were prepared by using dimethylolpropionic acid (DMPA) and methacrylic anhydride (MAAH) to modify ESO and then blended with high-functional active diluent trimethylolpropane triacrylate (TMPTA). Furthermore, FTIR, 1H NMR, and GPC were used to analyze the molecular structure and molecular weight of the oligomers. The oligomers (DMA/MAAESO and DMA/MAAESO-TM) had high esterification rate, curing degree, and good storage stability. The cured coatings from DMA/MAAESO and DMA/MAAESO-TM oligomers had significantly improved thermal stability, tensile, and coating properties. In all samples, DMA/MAAESO-TM cured coating had excellent coating performances. The glass transition temperature (Tg) of DMA/MAAESO-TM was 78.1°C, and its crosslink density (νe) was 6.87 × 10−3 mol/cm3. The hardness, curing time, gloss, flexibility, and impact resistance were H, 20 s, 108.5, 1 mm, and 50 cm, respectively.
Acrylic photopolymer resins are widely used in stereolithographic 3D printing. However, the growing demand for such thermosetting resins is weighing on global issues such as waste management and fossil fuel consumption. Therefore, there is an increasing demand for reactive components that are biobased and enable recyclability of the resulting thermoset products. In this work, the synthesis of a photo-cross-linkable molecule containing dynamic imine bonds based on biobased vanillin and dimer fatty diamine is described. Using the biobased building blocks, formulations containing reactive diluent and a photoinitiator were prepared. The mixtures could be rapidly cross-linked under UV light, yielding vitrimers. Using digital light processing, 3D-printed parts were prepared, which were rigid, thermally stable, and reprocessed within 5 min at elevated temperature and pressure. The addition of a building block containing a higher concentration of imine bonds accelerated the stress relaxation and improved the mechanical rigidity of the vitrimers. This work will contribute to the development of biobased and recyclable 3D-printed resins to facilitate the transition to a circular economy.
Dynamic cross-linked biobased vitrimers can be recycled, reprocessed, and degraded via bond exchange reactions. However, the competitive raw materials and the tedious preparation process still bring challenges for these sustainable...
The raw materials of commercial resin for photoresists nearly all come from petroleum resources. To follow the policy of “green chemistry”, it is urgent to employ renewable, biodegradable, green biomass resources instead of petroleum for the construction of photoresist resin. In this study, the alkaline soluble biobased epoxy acrylic resins are successfully prepared via a ring-opening reaction of epoxidized soybean oil (ESO) with the modified acrylic precursor (MMHEA), followed by diisocyanate modifying to introduce a small amount of polyurethane. The structures of the precursor and product resin are characterized and determined by FT-IR and ¹H NMR analysis. Subsequently, the properties of the resins and the related UV-curable coating films are tested detailedly. The results show that the product resin modified by diisocyanate possesses significantly improved viscosity (higher than 123 Pa s), and the UV-curable coating film containing hexamethylene diisocyanate has a moderate crosslinking density of 1443.18 mol m⁻³ and the excellent mechanical performances with the tensile strength of 20.40 ± 0.53 MPa, elongation at break of 30.74 ± 1.00% and toughness of 4.44 ± 0.11 MJ m⁻³. Moreover, the UV-curable coating films can dissolve completely in 10 wt% NaOH solution at room temperature within 40 min. The prepared product resin is in line with the requirements of photoresist, which can be used in the printed circuit boards. This study develops and provides a solvent-free and one-pot method to prepare biobased epoxy acrylic resins, which are suitable to use as photoresist resin. The use of biomass raw materials and green UV-curing technology follows the principles of green chemistry. And the preparation method of biobased functionalized resins with universal applicability can be easily extended to use in large-scale industrial resin production construction.
Developing recyclable biobased photopolymers for UV-curable 3D printing is of great significance for sustainable development of 3D printing industry. In this work, novel recyclable and reprintable castor oil (CO)-based photopolymers for digital light processing (DLP) 3D printing were developed via hindered urea bonds, a type of dissociating dynamic covalent bonds. Remarkably, the printed objects could be recycled in 4 h at 90 oC or 2 h at 100 oC without any catalysts or solvents, and the recycled resins had similar physiochemical properties, polymerization kinetics, and printing resolutions as the original resin. Furthermore, reprintable sacrificial molds and thermochromic materials were achieved with the optimal biobased resin, which can be used in complicated model casting and information encryption/anti-counterfeiting areas. In particular, thermochromic microcapsules could be recycled nondestructively from the printed thermochromic materials and reused in DLP 3D printing.
UV-curing 3D printing technology has greatly facilitated the development of manufacturing industry. However, there still are some crucial drawbacks to UV-curing 3D printed materials, i.e., the anisotropic mechanical strength, curing shrinkage and warpage. Herein, UV-induced disulfide metathesis able to rearrange the crosslinked network is adopted to overcome these difficulties. A disulfide bond-containing acrylate (MA-SS) is synthesized and incorporated into a 3D printing photosensitive resin. The photopolymerization kinetics indicate that the moderate amount of MA-SS can promote the photopolymerization conversion, while excessive MA-SS will decrease the conversion. The MA-SS can also greatly improve the tensile strength of 3D printed materials, owing to the more homogenous crosslinked networks and higher crosslinking density. Moreover, the anisotropic tensile strength between x- and z- axis is greatly reduced by the MA-SS, since disulfide metathesis can enhance the adhesion between printing layers. Furthermore, the 3D printed materials can be reversibly transformed from one shape to another by virtue of UV-induced disulfide metathesis. More importantly, the seriously warped 3D printed materials can be effectively rectified under the action of UV irradiation, where the warpage is significantly decreased from 6% to 1~2%. Therefore, this facile strategy of rearranging the crosslinked networks can conquer the drawbacks within UV-curing 3D printing materials to fulfill high-precision 3D printed materials.