Isobornyl Acrylate Research Articles

Material Characterization of Silicones for Additive Manufacturing.

Three-dimensional printing is ideally suited to produce unique and complex shapes. In this study, the material properties of polysiloxanes, commonly named silicones, produced additively by two different methods, namely, multi-jet fusion (MJF) and material extrusion (ME) with liquid printing heads, are investigated. The chemical composition was compared via Fourier-transform infrared spectroscopy, evolved gas analysis mass spectrometry, pyrolysis gas chromatography coupled to mass spectrometry, and thermogravimetry (TGA). Density and low-temperature flexibility, mechanical properties and crosslink distance via freezing point depression were measured before and after post-treatment at elevated temperatures. The results show significant differences in the chemical composition, material properties, as well as surface quality of the tested products produced by the two manufacturing routes. Chemical analysis indicates that the investigated MJF materials contain acrylate moieties, possibly isobornyl acrylate linking branches. The hardness of the MJF samples is associated with crosslinking density. In the ashes after TGA, traces of phosphorus were found, which could originate from initiators or catalysts of the curing process. The ME materials contain fillers, most probably silica, that differ in their amount. It is possible that silica also plays a role in the processing to stabilize the extrusion strand. For the harder material, a higher crosslink density was found, which was supported also by the other tested properties. The MJF samples have smooth surfaces, while the ME samples show grooved surface structures typical for the material extrusion process. Post-treatment did not improve the material properties. In the MJF samples, significant color changes were observed.

Monoclonal Antibody Delivery Using 3D Printed Biobased Hollow μNe3dle Arrays for the Treatment of Osteoporosis.

Transdermal microneedles have demonstrated promising potential as an alternative to typical drug administration routes for the treatment of various diseases. As microneedles offer lower administration burden with enhanced patient adherence and reduced ecological footprint, there is a need for further exploitation of microneedle devices. One of the main objectives of this work was to initially develop an innovative biobased photocurable resin with high biobased carbon content comprising isobornyl acrylate (IBA) and pentaerythritol tetraacrylate blends (50:50 wt/wt). The optimization of the printing and curing process resulted in μNe3dle arrays with durable mechanical properties and piercing capacity. Another objective of the work was to employ the 3D printed hollow μNe3dles for the treatment of osteoporosis in vivo. The 3D printed μNe3dle arrays were used to administer denosumab (Dmab), a monoclonal antibody, to osteoporotic mice, and the serum concentrations of critical bone minerals were monitored for six months to assess recovery. It was found that the Dmab administered by the 3D printed μNe3dles showed fast in vitro rates and induced an enhanced therapeutic effect in restoring bone-related minerals compared to subcutaneous injections. The findings of this study introduce a novel green approach with a low ecological footprint for 3D printing of biobased μNe3dles, which can be tailored to improve clinical outcomes and patient compliance for chronic diseases.

Evaluation of various monofunctional monomers for the development of fracture tough dental materials exhibiting a low crosslink density

3D printing of fracture tough dental materials that additionally exhibit excellent mechanical properties is challenging. Nowadays, most of the 3D printing dental materials contain a mixture of highly reactive dimethacrylates. The corresponding printed materials exhibit a high crosslink density and are particularly brittle. They are therefore not suitable for additive manufacturing of fracture tough denture bases. Recently, an efficient technology based on the combination of a urethane dimethacrylate macromonomer with a monofunctional monomer and a poly(ɛ-caprolactone)-polydimethylsiloxane-poly(ɛ-caprolactone) triblock copolymer was developed. Materials exhibiting a low crosslink density, excellent mechanical properties, and high fracture toughness were obtained. In this article, further developments of this highly efficient technology are described. A wide range of monofunctional monomers (both methacrylates and acrylates) was evaluated in this system. It was shown that the structure of the selected monofunctional monomer has a strong influence on the mechanical properties (flexural strength and modulus) as well as on the fracture toughness of the light cured materials. Thanks to the formation of nanostructures, a strong increase of fracture toughness was obtained upon addition of the toughening agent (poly(ɛ-caprolactone)-polydimethylsiloxane-poly(ɛ-caprolactone) triblock copolymer). The most promising materials were the ones based on the following monofunctional monomers: 2-phenoxyethyl methacrylate, (octahydro-4,7-methano-1H-indenyl)methyl acrylate, isobornyl acrylate, tetrahydrofurfuryl methacrylate and 4-tert-butylcyclohexyl acrylate. Indeed, these materials exhibited excellent mechanical properties (90.0 ± 3.8 MPa < flexural strength < 102.6 ± 4.7 MPa; 2402 ± 90 MPa < flexural modulus < 2714 ± 68 MPa) combined with high fracture toughness (1.89 ± 0.06 MPa m1/2 ≤ maximum stress intensity factor (Kmax) ≤ 2.18 ± 0.08 MPa m1/2; 418 ± 14 J m−2 ≤ work of fracture (Wf) ≤ 591 ± 25 J m−2). The measured Kmax and Wf were even significantly higher than the values reported for Probase Hot (Kmax = 1.44 ± 0.18 MPa m1/2; Wf = 270 ± 30 J m−2), a clinically proven and well-established PMMA based denture base material from Ivoclar. The successful DLP 3D printing of a monoblock denture using the most promising formulation confirmed the great potential of this technology for the development of 3D printing fracture tough denture bases.

UV-Cured Highly Crosslinked Polyurethane Acrylate to Serve as a Barrier against Chemical Warfare Agent Simulants.

Ultraviolet (UV) curing is an efficient and environmentally friendly curing method. In this paper, UV-cured polyurethane acrylates (PUAs) were investigated as potential military coatings to serve as barriers against chemical warfare agents (CWAs). Seven UV-cured PUA coatings were formulated utilizing hydroxyethyl methacrylate-capped hexamethylene diisocyanate trimer (HEMA-Htri) and trimethylolpropane triacrylate-capped polycarbonate prepolymer (PETA-PCDL) as the PUA monomers. Isobornyl acrylate (IBOA) and triethyleneglycol divinyl ether (DVE-3) were employed as reactive diluents. Gas chromatography was utilized to investigate the constitutive relationships between the structures of the PUA coatings and their protective properties against simulant agents for CWAs, including dimethyl methylphosphonate (DMMP), a nerve agent simulant, and 2-chloroethyl ethyl sulfide (CEES), a mustard simulant. The glass transition temperature (Tg) and crosslinking density (υe) of PUAs were found to be crucial factors affecting their ability to serve as barriers against CWAs. The incorporation of IBOA units led to enhanced Tg and barrier performance of the PUAs, resulting in a DMMP retention of less than 0.5% and nearly 0 retention of CEES. However, an excessive introduction of polycarbonate chains decreased the υe and barrier performance of the PUAs. These findings may offer valuable insights for enhancing the protection of UV-cured PU coatings against CWAs.

Influence of reactive diluent composition on properties and bio-based content of itaconic acid-based additive manufacturing materials

Among the additive manufacturing techniques, UV-curing processes are of special interest, as they allow for the fabrication of thermosetting materials with high resolutions and optical clarity. Traditionally, these processes require the use of formulations, consisting of polyester or polyurethane oligomers, combined with photoinitiators and reactive diluents. The latter are usually vinyl monomers such as acrylates or acrylamides, used to reduce the viscosity of the formulation and render it processable by additive manufacturing machines. In this work, we investigate whether a combination of diluents can be used to tune the thermomechanical properties of the printed materials, and if it can be exploited to increase their overall bio-based content without compromising their performance. To do so, a series of itaconic acid-based polyesters with different chemical structures (aliphatic–aromatic) were synthesized and formulated with reactive diluents acryloyl morpholine (ACMO) and isobornyl acrylate (IBOA). The physicochemical properties of the prepared formulations, together with their reactivity towards UV-light were assessed via photo differential scanning calorimetry (photo-DSC) and photo-rheology measurements. The same formulations were then used to fabricate test specimen via digital light processing (DLP) 3D printing, which were characterized on their thermomechanical properties by means of dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) measurements. The glass transition temperature of the printed samples reached a maximum of 98 °C, while the diluent ratio could be used to manipulate the Tg in a linear trend. All materials of this study exhibited Td,5% above 250 °C, suggesting good thermal stability. These results show that materials with a very high bio-based content (up to 85%) and very promising thermomechanical properties could be obtained by employing a diluent mixture during the formulation phase.

Deriving a point of departure for assessing the skin sensitization risk of wearable device constituents with in vitro methods

Wearable devices are in contact with the skin for extended periods. As such, the device constituents should be evaluated for their skin sensitization potential, and a Point of Departure (PoD) should be derived to conduct a proper risk assessment. Without historical in vivo data, the PoD must be derived with New Approach Methods (NAMs). To accomplish this, regression models trained on LLNA data that use data inputs from OECD-validated in vitro tests were used to derive a predicted EC3 value, the LLNA value used to classify skin sensitization potency, for three adhesive monomers (Isobornyl acrylate (IBOA), N, N- Dimethylacrylamide (NNDMA), and Acryloylmorpholine (ACMO) and one dye (Solvent Orange 60 (SO60)). These chemicals can be used as constituents of wearable devices and have been associated with causing allergic contact dermatitis (ACD). Using kinetic DPRA and KeratinoSens™ data, the PoDs obtained with the regression model were 180, 215, 1535, and 8325 μg/cm2 for IBOA, SO60, ACMO, and NNDMA, respectively. The PoDs derived with the regression model using NAMs data will enable a proper skin sensitization risk assessment without using animals.

Contact Allergy to Allergens in the Swedish Baseline Series Overrepresented in Diabetes Patients with Skin Reactions to Medical Devices - A Retrospective Study from Southern Sweden.

Allergic contact dermatitis is reported among individuals using continuous glucose monitoring systems and insulin pumps. The aim of this study was to describe contact allergy patterns for allergens in the Swedish baseline series and medical device-related allergens among users. Contact allergy to baseline series allergens and isobornyl acrylate was compared between diabetes patients and dermatitis patients patch-tested at the Department of Occupational and Environmental Dermatology during 2017 to 2020. Fifty- four diabetes patients and 2,567 dermatitis patients were included. The prevalence of contact allergy to fragrance mix II and sesquiterpene lactone mix was significantly higher in diabetes patients compared with dermatitis patients. Of the diabetes patients 13.0% and of the dermatitis patients 0.5% tested positive to sesquiterpene lactone mix (p < 0.001). Of the diabetes patients 7.4% and of the dermatitis patients 2.3% tested positive to fragrance mix II (p = 0.041). Of the diabetes patients 70.4% tested positive to medical device-related allergens. Of the diabetes patients 63.0% and of the dermatitis patients 0.2% were allergic to isobornyl acrylate (p < 0.001). In conclusion, not only medical device-related contact allergies, but also contact allergy to baseline series allergens (fragrance mix II and sesquiterpene lactone mix), is overrepresented in diabetes patients who use medical devices.

Allergic contact dermatitis to isobornyl acrylate in a home nail glue.

Allergic contact dermatitis to isobornyl acrylate in a home nail glue.

Allergic contact dermatitis to isobornyl acrylate in a hospital wristband.

Allergic contact dermatitis to isobornyl acrylate in a hospital wristband.

Enhanced adhesive and mechanically robust silicone-based coating with excellent marine anti-fouling and anti-corrosion performances.

Poly(dimethylsiloxane) (PDMS) is widely used in marine antifouling coatings due to its low surface energy property. However, certain drawbacks of PDMS coatings such as poor surface adhesion, weak mechanical properties, and inadequate static antifouling performance have hindered its practical applications. Herein, condensation polymerization is utilized to prepare PDMS-based polythiamine ester (PTUBAF) coatings that consist of PDMS, polytetrahydrofuran (PTMG), 2, 3, 5, 6-tetrafluoro-1, 4-benzenedimethanol (TBD) as the main chains and isobornyl acrylate(IBA) as the antifouling group. The surface adhesion to the substrate is enhanced due to the hydrogen bond between the coated carbamate group and the hydroxyl group on the surface of the substrate. Mechanical properties of PTUBAF are significantly improved due to the benzene ring and six-membered ring biphase hard structure. The strong synergistic effect of bactericidal groups and low surface energy surface endows the PTUBAF coating with outstanding antifouling performance. Due to the low surface energy surface, the PTUBAF coatings are also found to possess excellent anti-corrosion. Furthermore, since the PTUBAF coatings exhibit a visible light transmittance of 91 %, they can applied as protective films for smartphones. The proposed method has the potential to boost the production and practical applications of silicone-based coatings.

Design of near-infrared responsive self-healing photocured polyurethane materials with thiourethane bonds

In this work, a photopolymerizable polyurethane oligomer (PETU) with thiourethane bonds was designed and synthesized. Afterwards, the near-infrared responsive self-healing polyurethane films (PETU-HI-X) were fabricated by photopolymerization using homemade PETU, polydopamine (PDA), and commercially available isobornyl acrylate (IBOA) and 2-hydroxyethyl acrylate (HEA). PETU-HI-X have good photopolymerization and photothermal conversion performance. The as-prepared near-infrared responsive self-healing polyurethane polymer PETU-HI-1.0 exhibited a tensile stress of 1.06 MPa, strain of 1021 %, initial decomposition temperature of 290 °C. In addition, the temperature of the material can rise to more than 100 °C after irradiation with near-infrared light for 3 min, showing excellent photothermal conversion performance, based on which the material shows more than 90 % self-healing efficiency after irradiation with near-infrared light for 30 min. More importantly, the near-infrared responsive self-healing polyurethane polymer PETU-HI-1.0 also has an excellent degradation property. The self-healing polyurethane films have also been used to prepare the flexible electronic device that can be healed and fully restored their conductivity after getting damaged.

New device, 'old' allergens. Allergic contact dermatitis caused by the Dexcom G7 glucose sensor.

Allergic contact dermatitis (ACD) has been reported as an adverse effect from the use of several glucose sensors and insulin pumps from different manufacturers. Isobornyl acrylate (IBOA) has been identified as a major culprit sensitizer, but also other acrylates and (modified) colophonium have been reported as causes of ACD. To report the two first cases diagnosed with ACD caused by the Dexcom G7 (DG7) glucose sensor. Two children with suspected ACD from DG7 were patch tested with our medical device series with an addition of selected test preparations including two variants of modified colophonium - methyl hydrogenated rosinate (MHR) and glyceryl hydrogenated rosinate (GHR). Both patients were also tested with acetone extracts made from different parts of the DG7 sensor. The extracts were analysed by gas chromatography-mass spectrometry (GC-MS). Both patients tested positive to IBOA, hydroabietyl alcohol and GHR. In addition, patient 1 had a positive reaction to MHR and patient 2 had a positive reaction to colophonium. The GC-MS analyses showed the presence of IBOA and colophonium-related substances in the DG7 extracts. Both patients were diagnosed with contact allergy to well-known medical device-related sensitizers. The presence of IBOA and (modified) colophonium in a newly introduced (on the Swedish market in 2023) glucose sensor is remarkable and indicates an inadequate toxicological assessment of the materials used in the sensor.

Effect of isobornyl acrylate and hexanediol diacrylate on the properties of UV-curable resin developed from suberic acid-derived polyester polyol

Effect of isobornyl acrylate and hexanediol diacrylate on the properties of UV-curable resin developed from suberic acid-derived polyester polyol

3D printed microfluidic valve on PCB for flow control applications using liquid metal

Direct 3D printing of active microfluidic elements on PCB substrates enables high-speed fabrication of stand-alone microdevices for a variety of health and energy applications. Microvalves are key components of microfluidic devices and liquid metal (LM) microvalves exhibit promising flow control in microsystems integrated with PCBs. In this paper, we demonstrate LM microvalves directly 3D printed on PCB using advanced digital light processing (DLP). Electrodes on PCB are coated by carbon ink to prevent alloying between gallium-based LM plug and copper electrodes. We used DLP 3D printers with in-house developed acrylic-based resins, Isobornyl Acrylate, and Diurethane Dimethacrylate (DUDMA) and functionalized PCB surface with acrylic-based resin for strong bonding. Valving seats are printed in a 3D caterpillar geometry with chamber diameter of 700 µm. We successfully printed channels and nozzles down to 90 µm. Aiming for microvalves for low-power applications, we applied square-wave voltage of 2 Vpp at a range of frequencies between 5 to 35 Hz. The results show precise control of the bistable valving mechanism based on electrochemical actuation of LMs.

Acrylates in artificial nails-Results of product analyses and glove penetration studies.

Artificial nail materials are mixtures that are prone to contain several sensitizing (meth)acrylates. It is not known whether the listing of (meth)acrylates is correct in these products' packages. Protective gloves suited for nail work are needed. To analyse (meth)acrylates in gel nail and acrylic nail products chemically and to compare the results with the information in the product labels, and to study penetration of artificial nail materials through selected disposable gloves. We analysed 31 gel nail products and 6 acrylic nail products for their (meth)acrylate content by gas chromatography-mass spectrometry (GC-MS). We tested the penetration of two nail products through three disposable gloves: nitrile rubber, neoprene rubber and polyvinyl chloride (PVC). Altogether 32/37 products contained (meth)acrylates. In all of them, there was discrepancy between the listed (meth)acrylates and those discovered in the analysis. The commonest (meth)acrylates were hydroxyethyl methacrylate (HEMA, 20/37 samples) and hydroxypropyl methacrylate (HPMA, 9/37 samples), but many of the product packages failed to declare them. Isobornyl acrylate (IBA) was discovered in nine gel nail products. The neoprene glove could withstand nail gel for 20 min and thin nitrile glove and PVC glove for 5 min. Acrylic nail liquid penetrated through disposable gloves quickly. Labelling of artificial nail products was notably incorrect on most products. Requirements for product labelling must be updated so that the risk of sensitization associated with artificial nail products is clearly indicated. Disposable gloves can probably be used short-term in gel nail work, whereas disposable gloves do not protect the user from acrylic nail liquids.

The Use of High‐Temperature Semi‐Batch Radical Polymerization to Synthesize Acrylate Based Macromonomers and Structured Copolymers

AbstractA high‐temperature starved‐feed semi‐batch operating policy is developed to produce p(acrylates) with high macromonomer content, taking advantage of side reactions inherent to acrylate radical polymerization. This operating strategy results in significantly higher macromonomer content for the polymerization of isobornyl acrylate (iBoA) versus n‐butyl acrylate (BA) under identical operating conditions. This is because steric hindrance favors fragmentation (i.e., terminal double bond (TDB) formation) over addition (i.e., short‐chain or long‐chain branch (LCB) formation), thus increasing the p(iBoA) TDB content and decreasing polymer dispersity. The p(iBoA) macromonomer solution serves as an excellent addition‐fragmentation agent to polymerize a second monomer in a single pot process controlled by sequential feeding, as demonstrates by the production of iBoA‐BA block and comb copolymer structures at different temperatures and macromonomer concentrations. The incorporation of the p(iBoA) macromonomer into a copolymer product is verified by various techniques, including polymer fractionation followed by TDB, composition, and molar mass analyses. Reaction temperature plays a key role in determining whether a blocky versus comb copolymer structure is produced. The ability to synthesize block and comb copolymers by radical polymerization without a mediating agent offers the potential to efficiently produce structured copolymers for industrial applications.

Customizing ultraviolet curable polymer‐ink properties via reactive diluent modification and viscosity control

AbstractIn inkjet 3D printing, material selection plays a crucial role in shaping both printing performance and material characteristics. Achieving the desired properties relies on precisely formulated compositions. In this context, ultraviolet (UV) curable polymers require specific viscosities, typically ranging from 3700 to 5700 mPa·s, to function effectively in 3D printing's material jetting technique, preventing complications during material dispensing. This study formulates UV‐curable polymers by blending four distinct monomers: Genomer 4247 Aliphatic Urethane Dimethacrylate, 1,10‐Decanediol Dimethacrylate, Isobornyl Acrylate, and Methyl Acrylate, within a controlled dark room environment at room temperature to prevent undesired crosslinking reactions during mixing. The selection of these monomers and their compositions is meticulous, considering their capacity to achieve specified viscosities and enhance overall material performance. This formulation process yields a wide range of UV‐curable polymer viscosities. The study employs comprehensive methodologies, including rheometry, Fourier transform infrared analysis, Soxhlet extraction, thermal analysis, and tensile testing, for rigorous evaluation of viscosity, curing efficiency, thermal characteristics, and mechanical performance. Notably, mechanical and chemical performance exhibits marginal differences within the viscosity range, attributed to UV‐curable polymer crosslinking, consistently exceeding 99% for all samples. However, the polymer composed of 98% v/v oligomer and methyl acrylate (MA) demonstrates notably better thermal and mechanical properties due to its 99.91% gel content crosslinking. Remarkable polymer fabrication thus occurs within the desired viscosity range.

Role of acrylates in the development of contact dermatitis in diabetic patients-A Polish dermatology tertiary centre experience.

In recent years, an increasing number of contact dermatitis cases triggered by acrylates contained in diabetes medical devices have been reported. Acrylates seem to play a major role in the development of irritant contact dermatitis and allergic contact dermatitis (ACD) in diabetic patients. To study a group of patients with contact dermatitis caused by diabetes medical devices with a focus on acrylates as possible allergens responsible for contact dermatitis. Fifteen patients with diabetes mellitus type 1 and contact dermatitis from diabetic devices were patch tested to 25 acrylate allergens. Three patients (20%) reacted to the following allergens: three patients reacted to isobornyl acrylate (IBOA) and one of them additionally to 2-hydroxyethyl acrylate (2-HEA); results were of clinical relevance. All three patients were using insulin pumps and glucose sensors (GS)-in one patient contact dermatitis was towards the insulin pump and the GS, in one patient only towards the insulin pump and in one patient only towards the GS. Twelve patients (80%) did not show any skin reaction towards the allergens tested. A majority of diabetic patients showed no reactions towards any acrylate allergen tested; yet, the presence of untested allergens must be kept in mind. IBOA proved to be a cause of ACD in diabetes patients. 2-HEA might be another culprit allergen, but its presence in the devices must first be confirmed.

UV-Cured Bio-Based Acrylated Soybean Oil Scaffold Reinforced with Bioactive Glasses.

In this study, a bio-based acrylate resin derived from soybean oil was used in combination with a reactive diluent, isobornyl acrylate, to synthetize a composite scaffold reinforced with bioactive glass particles. The formulation contained acrylated epoxidized soybean oil (AESO), isobornyl acrylate (IBOA), a photo-initiator (Irgacure 819) and a bioactive glass particle. The resin showed high reactivity towards radical photopolymerisation, and the presence of the bioactive glass did not significantly affect the photocuring process. The 3D-printed samples showed different properties from the mould-polymerised samples. The glass transition temperature Tg showed an increase of 3D samples with increasing bioactive glass content, attributed to the layer-by-layer curing process that resulted in improved interaction between the bioactive glass and the polymer matrix. Scanning electron microscope analysis revealed an optimal distribution on bioactive glass within the samples. Compression tests indicated that the 3D-printed sample exhibited higher modulus compared to mould-synthetized samples, proving the enhanced mechanical behaviour of 3D-printed scaffolds. The cytocompatibility and biocompatibility of the samples were evaluated using human bone marrow mesenchymal stem cells (bMSCs). The metabolic activity and attachment of cells on the samples' surfaces were analysed, and the results demonstrated higher metabolic activity and increased cell attachment on the surfaces containing higher bioactive glass content. The viability of the cells was further confirmed through live/dead staining and reseeding experiments. Overall, this study presents a novel approach for fabricating bioactive glass reinforced scaffolds using 3D printing technology, offering potential applications in tissue engineering.

Universal approach for developing reprocessable and reprintable plant oil-based resins for digital light processing 3D printing

Recently, researchers have shown great interest in the development of biobased and reprintable 3D printing materials for sustainable 3D printing. Herein, a method for developing plant oil (PO)-based digital light processing (DLP) printing resins that are both reprocessable and reprintable is proposed. Biobased UV-curable monomers (POPITs) containing dynamic hindered urea bonds (HUBs) from POs were synthesized via the thiol-ene click reaction. A range of DLP printing resins (POPIT-I) with high biobased content (52.6%–58.1%) were prepared by blending POPITs with the biobased dilute monomer isobornyl acrylate. These resins demonstrated good mechanical and thermal properties (e.g., tensile strength: 45.1–49.5 MPa and Tg: 74–92 °C), as well as high DLP printing quality. Reprocessable DLP printing was employed to fabricate large-volume parts through the dissociation and reorganization of HUBs, thereby reducing printing difficulty and printing time. Additionally, a powder blending and modification method was used to recycle and reprint printed materials. The printing materials, including printed green parts and discarded supporting materials, were milled into micron-sized powders and then blended with POPIT-I to prepare the powder blending resins. The milled powders in the powder blending resins were further modified by 2-(tert-butylamino) ethyl methacrylate to prepare reprinting resins. This process resulted in the grafting of C = C onto the powder surface, which eliminated heterogeneity between the powders and POPIT-I. The mechanical and thermal properties of the reprinting resins were comparable with those of POPIT-I even after three rounds of recycling. Furthermore, the reprinting method reported here is applicable to other dynamic covalent bond-based 3D printing systems.