UV-curable Polyurethane Research Articles

Erratum: Effect of Hydrophilic Bentonite as a Filler on Curing Performance of Pigmented UV Curable Polyurethane Acrylate Coating

Erratum: Effect of Hydrophilic Bentonite as a Filler on Curing Performance of Pigmented UV Curable Polyurethane Acrylate Coating

Preparation and Application of UV Curable Waterborne Organosilicon Acrylic Polyurethane with Controllable Silicon Content

Preparation and Application of UV Curable Waterborne Organosilicon Acrylic Polyurethane with Controllable Silicon Content

Optimization of UV-Curable Polyurethane Acrylate Coatings with Hexagonal Boron Nitride (hBN) for Improved Mechanical and Adhesive Properties.

Polymer coatings are widely used in industries for protection, decoration, and specific applications, typically including volatile organic compounds (VOCs) to achieve low viscosity. The growing environmental concerns and the anticipated limits on fossil feedstock have driven the coating industry towards eco-friendly alternatives, with UV-curing technology emerging as a promising solution due to its energy efficiency, low-temperature operation, reduced VOC emissions, and high curing speed. Polyurethane acrylates (PUAs) are critical in UV-curable formulations, offering excellent flexibility, impact strength, optical, and adhesion properties. However, UV-cured PUA coatings face limitations in thermal stability and tensile strength, which can be addressed by incorporating fillers. This study investigates the effects of multi-functionalized hexagonal boron nitride (hBN) nanoparticles on the mechanical, thermal, optical, and adhesion properties of UV-cured PUA films and coatings for pre-coated metals. The results demonstrated that incorporating hBN nanoparticles enhanced the mechanical and thermal properties of the nanocomposite films, with optimal performance observed at 0.5% hBN loading. Despite the improved properties, the FTIR spectra indicated that the low concentration of hBN did not produce significant changes, potentially due to the overshadowing signals from the difunctional polyurethane acrylate.

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.

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.

Efficient and eco-friendly UV-cured polyurethane coating: Harnessing thiol-yne systems for corrosion protection

The UV-curable coatings have received significant attention from researchers due to their excellent advantages in corrosion protection. However, there has not been much effort made to investigate the UV-curable thiol-yne system. This project aims to prepare effective and environmentally-friendly polyurethane coatings capable of being cured by UV light using thiol-yne systems. Utilizing the chain extender derived from the glycolysis of PET, the bis(2-hydroxyethyl) terephthalate (BHET) as a glycolysis product was synthesized via the glycolysis reaction. Polyurethanes (PUYNE: yne-terminated polyurethanes and PUSH: thiol-terminated polyurethanes) were synthesized by utilizing BHET, and by altering the quantity of the BHET, and PUX coatings were formed upon exposure to UV light. The impact of PUYNE molecular weight and the resulting amount of thiol-yne crosslinking on mechanical and thermal properties were evaluated, and corrosion resistance was examined with electrochemical impedance spectroscopy (EIS). PUX1, which had the lowest molecular weight and the highest number of thioether bonds, exhibited the superior corrosion resistance properties so that after 8 weeks of immersion in saline solution, the impedance modulus at 0.01 Hz was 1.43×108 Ω.cm2. This study provides insight into the application of thiol-yne systems in forming UV-cured coatings and their protective role in preventing corrosion.

Synthesis and characterization of ureidopyrimidinone-functionalized polyurethane acrylates and their hybrid nanocomposites for UV coating applications

In this study, ureidopyrimidinone moieties (UPy), capable of physical crosslinking via quadruple hydrogen bonding, were successfully incorporated into UV-curable polyurethane acrylate prepolymers. First, a hydroxyl-terminated unsaturated ester monomer was synthesized and reacted with isophorone diisocyanate to create a hydroxyl-terminated UV-curable urethane oligomer (U–OH). Then, isocyanate-terminated building blocks (UPy moieties and an acrylate-based photosensitive monomer) were synthesized and used in various ratios to functionalize U–OH for the preparation of a series of UV-curable UPy-containing polyurethane acrylate (PUA) resins. The resulting products were structurally characterized using 1H NMR and FTIR spectroscopy. Furthermore, organic–inorganic hybrid nanocomposites were obtained by introducing silane coupling agents into PUA resins using the sol–gel process. A series of UV-curable UPy-containing PUA coatings and hybrid nanocomposites were prepared, and their synergistic effect on coating properties was investigated. The dynamic mechanical analysis revealed that the Tg of the samples increased with increasing UPy content, although the mechanical properties remained largely unaltered, as shown by the stress–strain test. The studies also demonstrated that the hybrid nanocomposites exhibited higher decomposition temperatures and better thermal stability compared to pure PUAs. All the coatings exhibited good transparency in the visible region. An optical microscope was used to investigate the self-healing property by scratching the plexiglass panels with a razor blade. Among the other samples, the coating with the highest percentage of UPy content exhibited the best self-healing ability after heat treatment at 90 °C for 10 min.Graphical abstract

Biomimetic design of micro- and nano-wrinkle wood surface via coating reinforced with hyperbranched polymer grafted cellulose nanofibers for skin-tactile performance

Inspired from human skin, micro- and nano-wrinkled wood surface with skin-tactile performance was designed and developed using a waterborne UV-curable polyurethane acrylate coating and cellulose nofibers (CNF). To further improve the properties, the CNF was diacetylated to D-CNF and further grafted with a hyperbranched polymer containing rich end amino groups (HB-CNF). The surface structure and chemical reactions were characterized, and the skin-tactile performance of the coating was comprehensively investigated. The HB-CNF exhibited excellent dispersion in the coating, and extensive reactions occurred between the two through the –NH2 and terminal –NCO groups, resulting in much improved mechanical properties and durability. Micro-wrinkles with a width of approximately 12–15 μm and a height of 8–14 μm were created, and nano-protrusions of wrinkles ranging from to 50–100 nm were obtained. The coated surface was hydrophobic and exhibited high resilience after compression, with a gloss of 3.3 GU at an incident angle of 60° and a static friction coefficient of 0.26, both of which were similar to those of human skin. The results presented an effective strategy for high-performance wood products with a good feeling, which is helpful to improve the market competitiveness and meet the people's pursuit of a better life.

Biobased, self-healing, and recyclable polyurethane derived hydrogel-elastomer hybrids for efficient lubrication

Developing biobased hydrogel-elastomer hybrids with stable lubrication derived from self-healing and recyclable polymer matrix poses a key challenge in the field of medical devices. Herein, we reported a novel hydrogel-elastomer hybrid incorporating a tung oil (TO)-based, self-healing, and recyclable polyurethane (PU) substrate that exhibits exceptional hydrophilic and lubricating properties. Initially, a series of UV-curable PU elastomers containing dynamic hindered urea bonds (HUBs) derived from renewable TO were prepared. By adjusting the ratios of the cross-linking agent TO-based polyol and the chain-extending agent polytetramethyleneglycol, the mechanical and thermal properties of these elastomers could be tuned well. The as-prepared PU elastomers demonstrated remarkable dynamic properties, attributed to the dissociation and recombination of HUBs, enabling efficient self-healing and effective recycling through solvent or hot-pressing methods while preserving their mechanical properties. Furthermore, functional hydrogel-elastomer hybrids were obtained by applying UV-initiated polymerization method to generate hydrogel coatings onto the optimized PU elastomer surface. Compared to the pristine PU material, the resulting hydrogel-elastomer hybrids exhibited excellent lubricity in aqueous environments, resulting from the formation of a robust hydration layer facilitated by electrostatic forces. Overall, our current research work provides key design inspiration for developing next-generation medical devices from sustainable and recyclable functional biomaterials.

Encouragement of Graphite and Graphene Oxide Particles on Corrosion Protection Properties for Polyurethane Palm Oil Based UV Curable Coating

This research explores the impact of derivative graphite additives in enhancing the corrosion prevention system of UV curable polyurethane coatings based on palm oil. UV irradiation technique was used in this study to produce cured protection coating. Two types of particles, respectively graphite and graphene oxide were used to understand the differential of both particles in physicomechanical behaviour of the curable coating. The study delves into the formulation and characterization of these coatings, assessing their effectiveness in preventing corrosion. The polymerisation effect by UV irradiation and influence of filler (graphene oxide and graphite) on physical properties of coating were studied by using Fourier Transform Infrared Spectroscopy (FTIR) and gel content together with hardness test. Besides that, X-ray Diffraction (XRD) and Field emission scanning electron microscopy (FESEM) were used to investigate the morphology of curable coating. Meanwhile Electro impedance spectroscopy (EIS) and contact angle measurement were carried out to investigate the related behaviour on corrosion protection properties. All the results were concluded to explain the role of graphite and graphene oxide in curable coating crosslink network. The finding in this study indicates that tortuosity structured which formed by graphite and graphene oxide in UV curable coating matrix were successfully retard corrosion rate per year on mild steel from 31.24 mpy to 43.91 x 10-6 mpy. This work aims to provide valuable insights into the development of eco-friendly and efficient corrosion protection solutions in the realm of coatings and materials science.

A study on the fabrication of metal microneedle array electrodes for ECG detection based on low melting point Bi–In–Sn alloys

This study describes the fabrication and characteristics of microneedle array electrodes (MAEs) using Bismuth–Indium–Tin (Bi–In–Sn) alloys. The MAEs consist of 57 pyramid-shaped needles measuring 340 μm wide and 800 μm high. The fabrication process involved micromolding the alloys in a vacuum environment. Physical tests demonstrated that Bi–In–Sn MAEs have good mechanical strength, indicating their suitability for successful skin penetration. The electrode–skin interface impedance test confirmed that Bi–In–Sn MAEs successfully penetrated the skin. Impedance measurements revealed the importance of insulating the microneedle electrodes for optimal electrical performance, and a UV-curable Polyurethane Acrylate coating was applied to enhance insulation. Electrocardiogram measurements using the Bi–In–Sn MAEs demonstrated performance comparable to that of traditional Ag/AgCl electrodes, which shows promise for accurate data collection. Overall, the study demonstrates successful, minimally-invasive skin insertion, improved electrical insulation, and potential applications of Bi–In–Sn microneedle array. These findings contribute to advancements in microneedle technology for biomedical applications.

UV-curing polyurethane pressure-sensitive adhesive with high shear strength and good adhesion properties inspired by spider silk

It is a challenge to develop polyurethane pressure-sensitive adhesive (PU-PSA) simultaneously with good cohesion and adhesion properties. Inspired by the structure of multiple hydrogen bonds in spider silk, we introduced Acylsemicarbazide (ASCZ) moiety that can form multiple hydrogen bonds in the polymer network into PU-PSA. The characteristic absorption peaks of ester groups at 1600–1780 cm−1 were analyzed in FTIR testing, and the results showed that ASCZ formed multiple hydrogen bonds in PU-PSA, and the hydrogen bond content increased with the increase of ASCZ content. In particular, PUA-AD20% with 24.3 % hydrogen bond content showed higher shear strength (0.51 MPa) and debonding energy (3.3 KJ m−2). Rheological tests showed that PU-PSA storage modulus and loss modulus increased with increasing frequency, which was highly frequency dependent. Therefore, as dynamic and reversible sacrificial bonds, hydrogen bonds can dissipate energy efficiently and resist external forces. In addition, the ASCZ component also provided PU-PSA with the polar groups required for adhesion. Therefore, PUA-AD20% had excellent adhesion properties. Compared to PUA, PUA-AD20% tack and peel strength increased by 36.1 % and 146.8 %, with values of 4.9 N and 11.6 N, respectively. In summary, this work offered a simple and versatile approach to designing PU-PSA with outstanding overall performance.

Enabling superior thermo-mechanical performance of hydrated salt-based phase change energy storage cementitious composite using graphene oxide reinforced micro-interface

Thermal energy storage cementitious composites (TESCCs) with encapsulated phase change materials (PCMs) were promising candidates for thermal comfort and energy saving in solar passive buildings. However, serious deterioration of mechanical properties and low heat transfer efficiency had hindered their application. In this study, a high-strength encapsulated PCM with a simple production process was developed by encapsulating eutectic hydrated salt PCM within UV-curable polyurethane acrelate resin, and the presented encapsulated PCM (UPE) was used to partially replace sand in cement mortar to prepare TESCC/UPE. Moreover, graphene oxide (GO) modification was conducted to form GO-TESCC/UPE, synergistically enhancing the mechanical strength and heat transfer efficiency. The compressive strength, microstructure and thermal conductivity of TESCCs were studied. Surface heat storage coefficient was presented to further assess the heat transfer and heat storage capacity of TESCCs. Moreover, GO-TESCC/UPE containing 20 vol% encapsulated PCM exhibited 28-day compressive strength of 35.3 MPa, with a 25% improvement over TESCC/UPE. The thermal conductivity and surface heat storage coefficient were also optimized by GO modification. The enhancement of thermal and mechanical properties can be attributed to the fact that GO-TESCC/UPE had a denser interface transition zone (ITZ) and lower harmful porosity due to the excellent compatibility between cement matrix and UPE. In addition, a simplified meso-mechanical model demonstrated that a denser ITZ can mitigate the stress concentration inside the matrix, thus enhancing mechanical properties of TESCCs. This study confirmed the effectiveness of reinforcing ITZ to enhance the thermo-mechanical properties of heat storage cementitious materials.

Effect of Photoinitiator Concentration and Film Thickness on the Properties of UV-Curable Self-Matting Coating for Wood-Based Panels

Matte coatings have found wide-ranging applications across diverse industries. In this study, self-matting films with surface wrinkles were produced by exposing UV-curable polyurethane acrylate (UV-WPUA) resin to 172 nm Xe2* excimer and medium-pressure mercury lamps. The gloss values, micromorphologies, water contact angles (WCAs), roughness values, and friction behaviors of UV-WPUA films with different photoinitiator (PI) concentrations and thickness were investigated for the first time. The results indicate that the gloss values of the films at the same thickness enhance with the increase of PI concentration, while the amplitude of wrinkles, roughness, and WCAs decrease; however, the friction coefficient shows insignificant variations. While the PI concentration is unchanged, an increase in film thickness results in a decrease in gloss value and an increase in roughness and friction coefficient. Nevertheless, the WCA is relatively constant. The PI concentration of 0.5 wt% (lowest gloss value of cured film) was utilized to prepare the UV-WPUA wood coating. The cured coating film exhibited low gloss (4.9 GU at 60° and 5.2 GU at 85°) and outstanding mechanical properties, including 3H pencil hardness, grade 0 adhesion, excellent wear resistance, and tensile property. These findings can be utilized to guide the development of self-matting wood coatings and the production of wood-based panels used in industrial finishing.

Synthesis of vanillin-based UV curable polyurethane dispersions for wood coating applications

Synthesis of vanillin-based UV curable polyurethane dispersions for wood coating applications

Evaluation Method and Influence Law of UV-Cured Polyurethane on the Self-Healing Performance of Asphalt and Asphalt Mixtures

To explore the effect of UV-curable polyurethane (UV-PU) on the self-healing performance (SHP) of asphalt and asphalt mixtures, this article conducted research in this area of the evaluation method and influenced the law. polyurethane (PU), Styrene-Butadiene-Styrene Block Copolymer (SBS Ι-C) and 70# asphalt and asphalt mixtures were introduced as the example of comparison. A method for evaluating the SHP of asphalt, sand asphalt mixture, and medium particle asphalt mixture using the healing index (HI) as an evaluation index was proposed, and the healing performance of various materials under different healing conditions was tested and analyzed. The research results indicate that, HI based on asphalt complex shear modulus (HIA), HI based on sand type asphalt mixture (AC-5) flexural tensile strength (HIAC-5), and HI based on medium grained asphalt mixture (AC-16) bending stiffness modulus (S) HIAC-16 can effectively reflect the SHP of asphalt, AC-5, and AC-16 under different healing conditions, and can be used as an evaluation indicator for SHP. The asphalt SHP is related to the asphalt type and the degree of initial loss and is highly correlated with the healing time. Compared to other asphalt types, the sensitivity of UV-PU or PU modified asphalt to initial loss is lower than that of SBS Ι-C modified asphalt, but higher than 70# asphalt. Under the same light healing time and initial degree of loss, the SHP of UV-PU modified asphalt AC-5 and AC-16 is significantly superior to other types of asphalt mixtures. Compared to asphalt, the self-healing time of AC-5 grade AC-16 is longer. The SHP of AC-16 is highly correlated with the loss degree associated with the initial S. The larger the initial loss degree of the S, the greater the loss rate of the HI.

3D printing polyurethane acrylate(PUA) based elastomer and its mechanical behavior

Liquid-crystal display(LCD) 3D printing, also known as light during 3D printing or photopolymer 3D printing, is a type of additive manufacturing technology that uses light-sensitive resin to create three-dimensional objects. This technology has gained popularity in recent years owing to its ability to create high-resolution, detailed objects with a wide range of materials, including shape-memory polymers, toughness resins, and elastomers. Elastomers are a type of polymer material that has the ability to stretch and deform under an applied force, but return to their original shape when the force is removed. The superior deformation recovery rate contributes to elastomer use in various industries, including automotive, aerospace, medical, and consumer goods. In this study, a UV-curable polyurethane acrylate(PUA) elastomer with an elongation of 100%–200% was developed. Using LCD 3D printing, we were able to fabricate Triply periodic minimal surface(TPMS) lattice structures with this elastomer investigated the compressive behavior of TPMS structures with different compressive ratios of 20%–50%. Our results demonstrate that this approach enables the creation of flexible energy-absorbing structures under cyclic loading. This study highlights the potential of LCD 3D printing technology for the production of elastomeric materials with tunable mechanical properties.

UV-Curable Polyurethane Acrylate Pressure-Sensitive Adhesives with High Optical Clarity for Full Lamination of TFT-LCD

Optically clear pressure-sensitive adhesives (PSAs) face the challenges presented by a range of electronic and touch screen applications. Although many efforts have been made to manipulate the optical and adhesion properties of ultraviolet (UV)-curable acrylate-based PSAs, further application and large-scale production are still limited owing to the intrinsically poor processability that stems from the large content of the high-vinyl-equivalent and low-viscosity acrylic monomers. Introducing a low-vinyl-equivalent and high-viscosity polyurethane acrylate (PUA) prepolymer into the formulation is a facile method to solve this issue without sacrificing the transparency. In this study, a series of PUA prepolymers are prepared to construct the model of PUA-co-2-ethylhexyl acrylate (2EHA), denoted as poly(PUA-2EHA). The influence of PUA prepolymer architectures (average functionality and molecular features) on the optical and adhesion properties is elaborately discussed. The chemical cross-linking-induced enhancement of the haze values of PUA-based PSAs is investigated for the first time. Moreover, an improved and uniform bright image display without blemish, which is usually called the Mura defect-free image display in the industrial field, is obtained by using poly(PUA-2EHA) as the optically clear adhesive for full lamination of the thin-film transistor liquid crystal display (TFT-LCD) module. The laminated TFT-LCD module could be disassembled easily without leaving the residue on the screen. These results provide clear design guidelines to regulate the properties of PUA-based PSAs, which are especially valuable for the large-scale industrial production of UV-cured PSAs and facilitate the development of display technologies.

Study on Press Formability and Properties of UV-Curable Polyurethane Acrylate Coatings with Different Reactive Diluents.

UV-curable coatings have numerous advantages, including environmental sustainability due to 100% solid content, economic feasibility attributable to relatively fast curing time, decent appearance, mechanical properties, chemical resistance, and abrasion resistance. However, UV-curable polyurethane acrylate coatings on metals apparently restrict their engineering applications owing to low mechanical properties and poor thermal stability, giving UV-curable coatings less flexibility and formability. In this study, we evaluated the property change of films according to the type of reactive diluents that lowers the viscosity of UV-curing coatings for pre-coated metal and has a substantial effect on the curing rate, viscoelastic properties, adhesive properties, and flexibility of the film. Moreover, there are many changes in the properties of coatings according to varied curing conditions in order to evaluate the oxygen inhibition phenomenon during the curing process in the atmosphere. In particular, to evaluate the effect of reactive diluents on forming formability, which is the most crucial property for the pre-coated metal, this study used conventional formability tests, such as t-bending or the Erichsen test. Moreover, a cross-die cup drawing mold with a similar form as failure and Safety Zone was utilized in order to obtain clearer information on its actual formability. The analysis on the effect of failure and safety zone on the material used in press forming was conducted by assessing limit punch height and forming a limit diagram of the manufactured film according to varied reactive diluents.

Bio-based upcycling of poly(ethylene terephthalate) waste to UV-curable polyurethane acrylate

A strategy for upcycling poly(ethylene terephthalate) into a high-value UV-curable polyurethane acrylate coating using bio-based cardanol diol as a glycolysis agent.