UV Curing Research Articles

Preparation of UV Curable Resins and their Toughening Effect on Bisphenol A‐Type Epoxy Acrylate

AbstractUV‐curable oligomers were synthesized by the reaction of ethylene glycol (EG) or 1,4‐butanediol (BDO) with isophorone diisocyanate (IPDI), and then terminated with hydroxyethyl acrylate (HEA). The chemical structures and molecular weight of the two oligomers were analyzed by Fourier transform infrared spectroscopy (FT‐IR), nuclear magnetic resonance (1H NMR and 13C NMR) and high performance liquid chromatography (HPLC). The obtained UV‐curable oligomers were separately mixed with bisphenol A‐type epoxy acrylate (EA) in different mass ratios. The resulting mixture was then mixed with the active diluent tetrahydrofuran acrylate (THFA) and the photoinitiator ethyl 2,4,6‐trimethylbenzoylphosphonate (TPO‐L) for UV curing. The curing reactions were performed at UV light intensity of 120 mW/cm2. The unsaturation conversion was monitored by real‐time infrared spectroscopy (real‐time FT‐IR). The mechanical properties and coating properties of the UV‐cured products were analyzed. The results showed that the synthesized UV‐curable oligomers had good toughening effect on EA, and the tensile strength of EA was also improved.

A recyclable, interchangeable optical switch with a PDLC-PVA-PSCLC structure and a low-voltage drive system

ABSTRACT Polymer dispersed liquid crystals (PDLC) and polymer stabilised cholesteric liquid crystals (PSCLC) are an indispensable class of electrically switchable materials, which have been widely applied in the fabrication of efficient and systematic smart windows. And doping nanoparticles in PDLC films can greatly improve their properties. In this study, PDLC films doped with zirconia nanoparticles were prepared by polymerisation-induced phase separation (PIPS) method, PSCLC films with nematic liquid crystals as the main part (reflecting wavelengths in the range of 400–600 nm) were prepared by UV curing method, and a novel optical switch was developed by combining these two liquid crystal films. The optimal bilayer sample was developed through a comparative analysis of properties among samples with varying formulations for each liquid crystal layer. This study represents a novel advancement in PSCLC and nanoparticle-doped PDLC bilayer structures, showcasing fully actuatable properties in the visible wavelength range. These structures exhibit excellent electro-optical properties and demonstrate stable, sustainable performance that can be regenerated. The findings underscore the potential of PDLC and PSCLC for applications in smart curtains and flexible materials, opening up new avenues for innovative technological applications.

An ultraviolet radiation protective transparent wood film retained natural wood texture and tactile properties

In this study, the raw material of Japanese cypress wood (Platycladus orientalis (Linn.) Franco) was used and subjected to a series of treatment, including replacement of the water in wood by organic solvent, liquid UV-curable coating impregnation, surface coating removal, and UV curing. By this method, we innovatively produced a new type of transparent wood film which we refer to as “wood-texture transparent wood” (WTTW). WTTW retained the color, texture, and tactility of wood, while exhibiting a high transmittance of light and haze. Macroscopic and microscopic tests demonstrated that by removing the excess coating on the impregnated wood film surface, the microstructure and roughness of the wood surface could be successfully preserved, and the wood-like tactility of WTTW could be realized. WTTW exhibits better properties than those of the original wood, including a maximum light transmittance of 72.3 %, a haze of 72.3 % (at 550 nm), a tensile strength of 123.90 MPa in the longitudinal direction, a tensile strength of 6.64 MPa in the cross direction, and a hardness of 81.8 HD. In comparison to the traditional transparent wood, WTTW not only streamlines the preparation process, but also preserves the original wood texture, which aligns more closely with the tenets of green environmental protection and is more suitable for home decoration and privacy protection.

A robust, durable and eco-friendly UV-cured wood film with self-matting and anti-fingerprint performance via wrinkled structure

With the changes in people's living standards and aesthetic perspectives, the matting films with wrinkled surfaces play a crucial role in fields such as decorative materials, wooden furniture, wood-based panels and industrial coatings. In this paper, the UV-cured polyurethane acrylate (PUA) films with self-matting and anti-fingerprint performance on the wood-based panels was prepared and developed the wrinkled surface by using excimer/mercury dual UV curing. The results showed that the roughness, wavelengths (λ) and amplitudes (A) of wrinkles surface were positively correlated with the excimer irradiation time and negatively correlated with the mercury lamp irradiation time. Furthermore, the increasing irradiation time improved the degree of curing and crosslink density of the cured films, which enhanced the mechanical properties and durability of the cured film. Consequently, the prepared UV-cured PUA film exhibited excellent self-matting with a gloss of 3.4 GU at an incident angle of 60° and maintained the gloss value < 5 GU after 500 times rubs and 1 hour corrosion. Additionally, the self-matting films with wrinkled surface enhanced the hydrophobicity and anti-fingerprint performance of the surface. Besides, the cured film presented high physical performance with hardness of 4 H and adhesion of 0 grade. These results provide a reference for the further application of self-matting films in wood-based panels, furniture and interior decoration fields.

Scalable production of double-layer superhydrophobic coating with superior adhesion and high corrosion resistance via screen printing and UV curing

This study addresses the challenges of mass production and extensive application of superhydrophobic coatings, focusing on adhesion and durability. We propose an innovative solution utilizing screen printing and UV curing techniques, offering a simple, replicable, and scalable process. Our two-step strategy involves applying a polyurethane diacrylate (PUA-2) adhesion layer to the glass surface through screen printing and UV curing to ensure superior adhesion. Next, a polyurethane hexaacrylate (PUA-6) based formulation is applied over the adhesion layer and subjected to light curing, resulting in excellent hydrophobicity, scratch resistance, and corrosion resistance. This method withstands a pullout force exceeding 5 MPa, achieving a water contact angle of 164.3° and a sliding angle of 1.6°. The coating maintains favorable superhydrophobicity after 80 rounds of sandpaper friction and demonstrates promising corrosion resistance in a 3.5 % NaCl solution. Notably, this approach streamlines large-scale production and delivers exceptional, well-defined performance, providing a promising avenue for widespread and sustainable applications of superhydrophobic coatings.

Crosslinking and Swelling Properties of pH-Responsive Poly(Ethylene Glycol)/Poly(Acrylic Acid) Interpenetrating Polymer Network Hydrogels.

This study investigates the crosslinking dynamics and swelling properties of pH-responsive poly(ethylene glycol) (PEG)/poly(acrylic acid) (PAA) interpenetrating polymer network (IPN) hydrogels. These hydrogels feature denser crosslinked networks compared to PEG single network (SN) hydrogels. Fabrication involved a two-step UV curing process: First, forming PEG-SN hydrogels using poly(ethylene glycol) diacrylate (PEGDA) through UV-induced free radical polymerization and crosslinking reactions, then immersing them in PAA solutions with two different molar ratios of acrylic acid (AA) monomer and poly(ethylene glycol) dimethacrylate (PEGDMA) crosslinker. A subsequent UV curing step created PAA networks within the pre-fabricated PEG hydrogels. The incorporation of AA with ionizable functional groups imparted pH sensitivity to the hydrogels, allowing the swelling ratio to respond to environmental pH changes. Rheological analysis showed that PEG/PAA IPN hydrogels had a higher storage modulus (G') than PEG-SN hydrogels, with PEG/PAA-IPN5 exhibiting the highest modulus. Thermal analysis via thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) indicated increased thermal stability for PEG/PAA-IPN5 compared to PEG/PAA-IPN1, due to higher crosslinking density from increased PEGDMA content. Consistent with the storage modulus trend, PEG/PAA-IPN hydrogels demonstrated superior mechanical properties compared to PEG-SN hydrogels. The tighter network structure led to reduced water uptake and a higher gel modulus in swollen IPN hydrogels, attributed to the increased density of active network strands. Below the pKa (4.3) of acrylic acid, hydrogen bonds between PEG and PAA chains caused the IPN hydrogels to contract. Above the pKa, ionization of PAA chains induced electrostatic repulsion and osmotic forces, increasing water absorption. Adjusting the crosslinking density of the PAA network enabled fine-tuning of the IPN hydrogels' properties, allowing comprehensive comparison of single network and IPN characteristics.

Aramid-Reinforced UV Curable Adhesive Resins for Use As an Interlayer in Laminated Glass.

Colorless, transparent, and mechanically robust aramid polymers are synthesized from two diamine monomers with strong electron-withdrawing groups, using low-temperature solution condensation with diacid chloride. The aramids dissolved very well in the liquid acrylamide monomers. When N,N-dimethylacrylamide (DMA) is used as a reactive diluent, films with the desired features are produced from the hybrid aramid-DMA resins via ultraviolet (UV)curing. The hybrid films are colorless and transparent in the visible region and showed an increase in the glass transition temperature, tensile strength, and elastic modulus in proportion to the aramid content. Laminated glass is manufactured using the hybrid resin as an interlayer, which exhibits very strong adhesion between the two sheets of glass, is not easily broken by an external impact, and do not scatter fragments. Moreover, the laminated glass do not distort images and functioned very effectively in UV blocking, soundproofing, and suppressing changes in the ambient temperature. Heat treatment further improves the light transmittance and impact resistance of the laminated glass. Laminated glass specimens with various fluorescence colors are also manufactured. Aramid-reinforced films prepared using N,N-diethylacrylamide as a reactive diluent underwent thermally induced phase separation in a wet state, providing smart glass with a privacy protection function.

High stretchable and self-adhesive multifunctional hydrogel for wearable and flexible sensors

Ionic conductive hydrogel has recently garnered significant research attention due to its potential applications in the field of wearable and flexible electronics. Nonetheless, the integration of multifunctional and synergistic advantages, including reliable electronic properties, high swelling capacity, exceptional mechanical characteristics, and self-adhesive properties, presents an ongoing challenge. In this study, we have developed an ionic conductive hydrogel through the co-polymerization of 4-Acryloylmorpholine (ACMO) and sodium acrylate using UV curing technology. The hydrogel exhibits excellent mechanical properties, high conductivity, superior swelling capacity, and remarkable self-adhesive attributes. The hydrogel serves as a highly sensitive strain sensor, enabling precise monitoring of both substantial and subtle human motions. Furthermore, the hydrogel demonstrates the capability to adhere to human skin, functioning as a human-machine interface for the detection of physiological signals, including electromyogram (EMG) signals, with low interfacial impedance. This work is anticipated to yield a new class of stretchable and conductive materials with diverse potential applications, ranging from flexible sensors and wearable bio-electronics to contributions in the field of artificial intelligence.

Versatile Underwater Pressure Sensitive Adhesive: UV Curing Synthesis and Substrate-Independent Adhesion.

The demand for underwater pressure sensitive adhesives (PSAs) is rapidly increasing in fields such as underwater engineering and biomedicine. However, the achievement of underwater adhesion of PSAs remains a challenge because of the hydration layer that hinders the interaction between the adhesive and the substrate. Herein, a new type of underwater PSA was synthesized by the copolymerization of hydrophobic unsaturated poly(1,2-butylene oxide) (UPBO) and hydrophilic itaconic acid monomers using solvent-free ultraviolet curing. The PSA has demonstrated substrate-independent underwater adhesion strengths ranging from 108 to 141 kPa on both hydrophilic (glass, wood, steel) and hydrophobic (PET, PMMA, PTFE) substrates. The underwater adhesion performance of PSA remains stable during 30 adhesion-detachment cycles and incubation in water for 20 days. Notably, PSA shows cytocompatibility, antimicrobial, and degradable properties and can be used for rapid hemostasis of skin wounds. Experimental characterizations confirm that the process of underwater adhesion is achieved by hydrophobic alkyl side chains of the PBO chain segments, which repel water at the adhesive-substrate interface. This study should provide both practical and facile design strategies for multifunctional underwater PSAs that can be used in a variety of applications.

A UV-curable silicone acrylate anti-smudge coating containing tertiary amines and Ti with the ability to prevent oxygen inhibition

UV curing technology has numerous advantages such as a fast curing speed, environmental friendliness, energy conservation, and thus it is widely used in industrial production and out daily life. Free-radical polymerization is the primary mechanism for UV curing technology. However, free-radical polymerization is susceptible to oxygen inhibition, which leads to incomplete curing when this approach is employed in the air. This paper describes a new silicone acrylate prepolymer, four double bonds and a tertiary amine group at each end of the prepolymers can effectively solve the oxygen inhibition. We synthesized an alkoxymethacryloxy titanium monomer (Ti-MA). This monomer was mixed with the prepolymer and UV cured, which resulted in improved coating properties. The results showed that the double bond conversion of the prepolymer reached 90.66 ± 0.5 % at 20 s, and the residual adhesion rate also exceeded 90 %. The hardness of the coating could reach pencil hardness level 4H with the addition of Ti-MA, and the water contact angle reached 104.5 ± 0.2°, as well as excellent anti-smudge and anti-fingerprint properties. This study provides a new method to solve the oxygen inhibition problem, which has a broad application prospect in the field of coatings.

Waterborne bio-based UV-thermal dual-curable coatings with excellent mechanical properties and thermal resistance based on citric acid modified epoxidised soybean oil

Waterborne bio-based UV-curable coatings have attracted enormous attentions due to their environment friendliness and safety. However, residual neutralizing agents, long-chain aliphatic hydrocarbons derived from epoxidised soybean oil, and the oxygen inhibition inherent in the UV curing process often cause poor thermal resistance and mechanical properties of the epoxidised soybean oil-based waterborne bio-based UV-curable coatings. Herein, the epoxidised soybean oil was hydrophilized by citric acid and poly (ethylene glycol) diglycidyl ether without the use of neutralizing agents. The hydrophilized epoxidised soybean oil was subsequently compounded with bisphenol A epoxy resin to prepare high-performance waterborne bio-based epoxy methacrylates. Finally, a high-performance waterborne bio-based UV-thermal dual-curable coating was obtained by blending waterborne bio-based epoxy methacrylates with waterborne isocyanate curing agent. The results demonstrated that waterborne bio-based epoxy methacrylates possess high bio-based content, low viscosity, and remarkable storage stability. Furthermore, waterborne bio-based UV-thermal dual-curable coatings with high cross-linking density exhibited outstanding mechanical properties and thermal resistance. For example, the waterborne bio-based UV-thermal dual-curable coatings P0805I4 exhibits a breaking elongation of 30.75%, maximum tensile strength of 16.68 MPa, T10% at 285.33 °C, and adhesion class level of 0. Our research not only introduces high-performance waterborne bio-based UV-thermal dual-curable coatings, thereby extending the application domains of soybean oil-derived waterborne bio-based coatings, but also presents a valuable strategy for advancing high-performance, sustainable, waterborne, and environmentally friendly materials.

Structure, Property Optimization, and Adsorption Properties of N,N'-methylenebisacrylamide Cross-Linked Polyacrylic Acid Hydrogels under Different Curing Conditions.

In this study, polyacrylic acid hydrogels were prepared by modulating the cross-linking agent mass ratio using UV and heat curing methods. The structures and properties of the hydrogels were characterized and analyzed using Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The results showed that the mechanical properties of the hydrogels prepared through UV curing were better than those prepared through heat curing. The maximum mechanical tensile strength of 139 kPa was achieved at a cross-linking agent mass ratio of 3.85% with 20 min of UV curing, and the maximum mechanical compressive strength of 0.16 MPa was achieved at a cross-linking agent mass ratio of 2.91% with 20 min of UV curing. However, the hydrogels prepared by heat curing had a higher tensile strength than those prepared using the heat curing method. In addition, the thermally cured hydrogels had higher water absorption and adsorption properties. Moreover, the PAA hydrogels prepared at cross-linking agent mass ratios of 1.91 and 2.91% with 2 h of the heat curing method had the best swelling properties. Moreover, the increase in the cross-linker mass concentration led to a decrease in the pore size and porosity and to a more compact structure.

Characteristics of phosphorus‑nitrogen based flame-retardant monomers for UV-curable coatings on battery PET pouches

In this study, photocurable monomers containing phosphorus–nitrogen groups were employed alongside UV curing technology to develop flame-retardant (FR) coatings pouch-type battery cells made from polyethylene terephthalate (PET). Three different monomers were synthesized: a phosphorus-containing urethane acrylate monomer (DUPPO), a phosphorus–nitrogen-containing urethane acrylate monomer (DA-Pi-U), and a phosphazene-containing phenyl methacrylate crosslinker (CP-PMA). These monomers, recognized for their flame-retardant properties, were utilized in binary and ternary coating formulations that were effectively cured via a UV-curing process. The molecular architectures of the synthesized monomers were verified through 1H and 31P nuclear magnetic resonance spectroscopy. The rheological curing behavior of the coating solutions was assessed using an oscillatory rheometer. In addition, the reactivity of the FR coating system was examined via Fourier transform infrared spectroscopy. The thermal and flame-retardant characteristics of the FR coatings were confirmed through thermogravimetric analysis, Raman spectroscopy, limiting oxygen index measurements, and scanning electron microscopy. The ternary FR coating system with CP-PMA exhibited superior thermal stability, flame retardancy, crosslinking density, and mechanical robustness, making it suitable for PET pouches. Furthermore, optimal coating conditions for the slot coating process were determined using a viscocapillary model, enhancing practical applicability in industrial settings.

Nanofibrous Conductive Sensor for Limonene: One-Step Synthesis via Electrospinning and Molecular Imprinting.

Detecting volatile organic compounds (VOCs) emitted from different plant species and their organs can provide valuable information about plant health and environmental factors that affect them. For example, limonene emission can be a biomarker to monitor plant health and detect stress. Traditional methods for VOC detection encounter challenges, prompting the proposal of novel approaches. In this study, we proposed integrating electrospinning, molecular imprinting, and conductive nanofibers to fabricate limonene sensors. In detail, polyvinylpyrrolidone (PVP) and polyacrylic acid (PAA) served here as fiber and cavity formers, respectively, with multiwalled carbon nanotubes (MWCNT) enhancing conductivity. We developed one-step monolithic molecularly imprinted fibers, where S(-)-limonene was the target molecule, using an electrospinning technique. The functional cavities were fixed using the UV curing method, followed by a target molecule washing. This procedure enabled the creation of recognition sites for limonene within the nanofiber matrix, enhancing sensor performance and streamlining manufacturing. Humidity was crucial for sensor working, with optimal conditions at about 50% RH. The sensors rapidly responded to S(-)-limonene, reaching a plateau within 200 s. Enhancing fiber density improved sensor performance, resulting in a lower limit of detection (LOD) of 137 ppb. However, excessive fiber density decreased accessibility to active sites, thus reducing sensitivity. Remarkably, the thinnest mat on the fibrous sensors created provided the highest selectivity to limonene (Selectivity Index: 72%) compared with other VOCs, such as EtOH (used as a solvent in nanofiber development), aromatic compounds (toluene), and two other monoterpenes (α-pinene and linalool) with similar structures. These findings underscored the potential of the proposed integrated approach for selective VOC detection in applications such as precision agriculture and environmental monitoring.

Preparation and properties of UV curing varnish suited for various substrates

UV-curing varnish has gained widespread application in the field of surface treatment due to its advantages such as low-temperature curing, easy fading, and environmental friendliness. The aim of this study is to develop a high-performance UV-curing varnish compatible with various substrates. Five prepolymers, Polymethyl Methacrylate (PMMA), Poly (methyl methacrylate-random-acrylic acid) P(MMA-r-AA), Poly (methyl methacrylate-random-glycidyl methacrylate-random-styrene) (P(MMA-r-GMA-r-St)), Poly (methyl methacrylate-random-butyl acrylate-random-glycidyl methacrylate) (P(MMA-r-BA-r-GMA)) and Poly (butyl acrylate-random acrylic acid-random glycidyl methacrylate-random styrene)(P(BA-r-AA-r-GMA-r-St)), were synthesized by free radical polymerization. The film-forming effect of prepolymer on 13 substrates such as glass, coated paper, polyethylene, polyethylene glycol terephthalate and low density polyethylene was investigated. Based on the results, the two prepolymers with the best film-forming properties were selected and combined with five distinct diluents and two types of photoinitiators to produce multiple UV-curing varnish formulations. The effects of the types of prepolymer, the types and contents of photoinitiator, the types of diluent and the ratios of prepolymer to diluent on the photocuring rate of UV curing varnish were investigated. The structures of prepolymer were characterized by Fourier infrared spectrometer. The experimental results show that PMMA and P(MMA-r-GMA-r-St) have better film-forming effects on 13 substrates. When the prepolymer is P(MMA-r-GMA-r-St), the photoinitiator is ITX, the photoinitiator content is 75 mg/mL, diethylenetriamine:GMA = 1:3 (diluent), and the ratio of prepolymer to diluent is 1:4, the photocuring rate of UV curing varnish is the fastest.

A transparent, strong, moldable wood laminated composite as a sustainable decorative building material

Delignified wood (DW) retaining its microstructure has increasingly been used as an alternative to synthetic or natural fibers in the preparation of fiber-reinforced composites for novel light-transmitting, high-strength structural materials. In this study, wood laminated composite (WLC) was prepared by impregnating with cycloaliphatic epoxy resin (CAE) and laminating using DW as a continuous reinforcing fiber. Results showed that DW effectively strengthened the resin matrix, increasing the epoxy resin's strength by 25.44 %, while CAE modified the wood's opacity, achieving a transmittance of up to 74.83 %. The mechanical and optical properties of the WLC can be effectively tuned through various lamination combinations. Additionally, due to the UV curing properties of CAE and its infiltration of DW, uncured WLC had long-term shade storage capability and excellent processability. The WLC developed in this study combines good processing, mechanical, and optical properties, making it an attractive option for sustainable home decoration and lightweight structural materials.

New type of UV cured low dielectric naphthalene resin: Structure-activity relationship of different substitution sites

UV-curing low dielectric materials exhibit wide applications in the field of additive manufacturing of electronic packaging, owing to their environmental protection, good thermal stability, low dielectric constant (Dk), and dielectric loss (Df). Wherein, one-step UV curing realizes process simplification of low dielectric materials gradually sparked widespread research. In this work, a series of novel naphthalene-based low dielectric materials were prepared for one-step UV curing. The double bond conversion rate of resins exceeds 90 % in a short time and the resins perform exceptional dielectric properties (Dk < 2.8, Df < 0.009, 110 MHz), high thermal stability (T5% > 270 °C), and hydrophobicity (water contact angle > 95°). Notably, 1,6-naphthalene dimethacrylate/Trihydroxymethylbutyl trimethylacrylate (1,6-NEA/TMPTA) suggests lowest dielectric performance (Dk = 2.19, Df = 0.005) with significant thermal stability (Tg = 190 °C, T5% = 367.4 °C) because the π-π conjugation of the asymmetric structure of 1,6-NEA, which allows for a greater variety of stacking patterns and increases the effective collisions between the reactive sites of the photosensitive monomer and the reactive diluent. This work has revealed the structure-activity relationship between the substituents on naphthalene derivatives and their photochemical properties, providing a novel methodology for the development of low dielectric electronic packaging materials through additive manufacturing techniques.

A New Approach for On-Chip Production of Biological Microgels Using Photochemical Cross-Linking.

Photochemical cross-linking is a key step for manufacturing microgels in numerous applications, including drug delivery, tissue engineering, material production, and wound healing. Existing photochemical cross-linking techniques in microfluidic devices rely on UV curing, which can cause cell and DNA damage. We address this challenge by developing a microfluidic workflow for producing microgels using visible light-driven photochemical cross-linking of aqueous droplets dispersed in a continuous oil phase. We report a proof-of-concept to construct microgels from the protein Bovine Serum Albumin (BSA) with [Ru(bpy)3]2+ mediated cross-linking. By controlling the capillary number of the continuous and dispersed phases, the volumetric flow rate, and the photochemical reaction time within the microfluidic tubing, we demonstrate the construction of protein microgels with controllable and uniform dimensions. Our technique can, in principle, be applied to a wide range of different proteins with biological and responsive properties. This work therefore bridges the gap between hydrogel manufacturing using visible light and microfluidic microgel templating, facilitating numerous biomedical applications.

Non-Isocyanate Urethane Acrylate Derived from Isophorone Diamine: Synthesis, Characterization and Its Application in 3D Printing.

In this paper, urethane-based acrylates (UA) were prepared via an environmentally friendly non-isocyanate route. Isophorone diamine (IPDA) reacted with ethylene carbonate (EC), producing carbamate containing amine and hydroxyl groups, which further reacted with neopentyl glycol diacrylate (NPGDA) by aza Michael addition, forming UA. The structures of the obtained intermediates and UA were characterized by 1H NMR and electrospray ionization high-resolution mass spectrometry (ESI-HRMS). The photopolymerization kinetics of UA were investigated by infrared spectroscopy. The composite with obtained UA can be UV cured quickly to form a transparent film with a tensile strength of 21 MPa and elongation at break of 16%. After UV curing, the mono-functional urethane acrylate was copolymerized into the cross-linked network in the form of side chains. The hydroxyl and carbamate bonds on the side chains have high mobility, which make them easy to form stronger dynamic hydrogen bonds during the tensile process, giving the material a higher tensile strength and elongation at break. Therefore, the hydrogen bonding model of a cross-linked network is proposed. The composite with UA can be 3D printed into models.

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.