UV-cured Films Research Articles

Characterization of an acrylic polymer under hygrothermal aging as an optically clear adhesive for touch screen panels

Optically clear adhesives (OCAs) are key components of touch screen panels (TSPs). It is important that OCAs do not affect the transparent electrodes in TSPs because OCAs are contacted to the transparent electrodes. Therefore, N-vinyl caprolactam (NVC) was incorporated in the composition of an acrylic pressure sensitive adhesive (PSA) with excluding an acidic component to maintain the cohesion for OCA preparation. With increasing amounts of NVC, the tack and peel strength of UV-cured PSA increased, but high amounts of NVC led to decreased peel strength. The UV-cured PSA films were placed in a high temperature and humidity chamber for 8 weeks to investigate the durability and corrosion property under hygrothermal conditions. In this study, the corrosion test method using copper foil was suggested as a simple and economical method and was used to evaluate the effect of NVC on the corrosion property of PSA. This method helped identify suitable OCAs that do not have corrosive property. PSA films containing more than 20wt% of NVC promoted the corrosion of copper foil under hygrothermal aging conditions. The caprolactam ring was opened by moisture, and the PSA structure morphed into a polar structure during the aging process. This change caused a glass transition shift, an increase in the storage modulus at the rubbery plateau, and an increase in peel strength. The surface free energy of the PSA films also increased due to the increase in the polar property. However, high amounts of NVC caused a decrease in the peel strength after 8 weeks of aging because of increased molecular interactions.

The quantitative effect of silica nanoparticles on optical properties of thin solid silica UV-cured films

A thin solid silica UV-cured film was prepared by coating the dispersion of commercial silica nanoparticles in a UV-curable acrylate monomer on a glass substrate using a bar coater. The silica UV-curable acrylate resin was stored for 24h in the dark for film formation and then transformed into the thin solid silica UV-cured films upon exposure to UV light at the wavelength of 254nm for 5min at ambient temperature. The amount of silica nanoparticles in the UV-cured films was varied from 1 to 30vol.% and then the optical properties of the coated glass were compared with the bare glass. The result revealed that the total transmittance of all the films is insignificantly different when the amount of silica nanoparticles increases. The total transmittance of all the coated glasses is similar to that of the bare glass indicating the transparency of the film. Although the total transmittance of the films is independent of the amount of particles, the improved diffuse transmittance of the films is obtained as the amount of particles increased. This is due to the enhanced multiple scattering that occurs in the film. The increased amount of silica nanoparticles also leads to the formation of the aggregated particles with a larger size and homogeneous dispersion as evidenced from the FE-SEM images. These indicated that the amount and distribution of the silica nanoparticles strongly affect the improved optical properties of the thin solid silica UV-cured film.

Use of graphite oxide and/or thermally reduced graphite oxide for the removal of dyes from water

Abstract Two types of carbonaceous materials, graphite oxide (GO x ) and thermally reduced graphite oxide (TRGO) were tested in the dyes removal from water. Two common synthetic aquatic pollutants, Orange II, an azo dye, and Rhodamine B, a xanthene dye, were selected as probe molecules and their bleaching was evaluated. We observed that the two materials act in a different way when dispersed in aqueous solution: TRGO acts as a good adsorbent material whereas GO x can be used as an efficient photosensitizer. Dye removal is almost complete in the dark in the presence of TRGO and within few minutes a steady-state concentration was achieved. On the contrary, in the case of GO x , adsorption is limited to almost 10–20% for both dyes, but this material is able to induce dyes photodegradation and almost 80% of the residual dyes are abated within 5 h of irradiation under simulated solar light. When the graphene derivatives were dispersed in UV-cured acrylic polymeric films, the reduction of the surface area dropped the adsorption properties of TRGO, whereas the photosensitizer properties of GO x were maintained and the bleaching of the two dyes was achieved.

Synthesis and Performances of UV-Curable Polysiloxane–Polyether Block Polyurethane Acrylates for PVC Leather Finishing Agents

A series of multifunctional UV-curable polysiloxane–polyether block polyurethane acrylates prepolymers (TSi1E9PUA, TSi3E7PUA, TSi5E5PUA, TSi7E3PUA, and TSi9E1PUA) used for polyvinyl chloride (PVC) leather finishing agents have been prepared and characterized by nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), and gel permeation chromatography (GPC). All five multifunctional prepolymers exhibited excellent photopolymerization efficiency and good yellowing resistance. And the content of polysiloxane in prepolymers obviously affected the viscosity, thermal stability, tensile strength, elongation at break, and surface hydrophobicity of the photopolymerization systems. The system with the prepolymer containing more polysiloxane segments presented a high viscosity, and UV-cured film had relatively good thermal stability, elongation at break, and surface hydrophobicity accordingly. The properties of the prepolymers well satisfied the application requirements for leather finishing agents. Furt...

Preparation of Fully Bio-Based UV-Cured Non-Isocyanate Polyurethanes From Ricinoleic Acid

Fully bio-based non-isocyanate polyurethane (NIPU) was facilely prepared by self-condensation of primary amide of ricinoleic acid under oxidation conditions. The resulting linear urethane oligomer (Mn = 1300 Da) as a viscous liquid was further cured under UV light irradiation to afford a polymer film with hardness of lower than 2B. Infrared spectra as well as changes of polymer appearance proved crosslinking of the linear NIPU. Hardness of UV-cured film was promoted to 4H when a certain amount of cardanol was added to the linear urethane oligomer, accompanied by manifest improvement of resistance to chemical media such as aqueous HCl, EtOH, toluene and THF.

Synthesis and properties of UV-curable polyurethane acrylates containing fluorinated acrylic monomer/vinyltrimethoxysilane

A series of UV-curable polyurethane acrylates containing fluorinated acrylic monomer (heptadecafluorodecyl methacrylate, PFA, 6 wt%)/vinyltrimethoxysilane (VTMS, 0–9 wt%) [FPUA6/0, FPUA6/3, FPUA6/6 and FPUA6/9, where the numbers indicate the wt% of PFA/VTMS] were synthesized from a reactive urethane oligomer (40 wt%) and diluents (60 wt%). This study examined the effect of bulky VTMS (0–9 wt%)/bulky IBOA (34–25 wt%) weight ratio on the properties of the UV-curable polyurethane acrylates for transparent anti-fouling coating materials. In the wavelength range of 400–800 nm, the transmittance % of the FPUA film samples increased markedly up to nearly 100 % with increase in the VTMS content up to 9 wt%. As the VTMS content increased, the storage modulus/tensile modulus/hardness of the UV-cured film samples increased significantly and the tensile strength/glass transition temperature increased a little; however, the elongation at break decreased significantly. XPS showed that the film–air surface of the UV-cured polyurethane acrylate film had a higher fluorine content than the film–dish interface indicating the gradient concentration of fluorine in the structure of the film from the film–air surface to the film–glass interface. As the VTMS content increased from 0 to 9 wt%, the surface tension of the UV-cured urethane acrylate films decreased from 17.2 to 15.9 mN/m, whereas the water/methylene iodide contact angles of the film–air surface increased significantly from 107.9/80.9° to 114.2.9/84.2°. These results suggest that the UV-curable polyurethane acrylate containing 9 wt% of VTMS has strong potential as a coating material for transparent antifouling applications.

Surface properties and surface patterning of UV-curable coating using perfluorosilane-treated nanosilica

In this work, a one-step film formation method is demonstrated to obtain the patterned surface of an acrylate photocuring coating using nano-silica particles treated with a perfluoroalkoxysilane ((heptadecafluoro-1,1,2,2-tetra hydrodecyl) triethoxysilane) as a nanoadditive. Nanosilica particles were treated with perfluoroalkoxysilane and used in a UV-curable matrix. The typical patterns on the surface of the UV-cured films are revealed in AFM images. The surface properties of the cured films were investigated by measuring water contact angle and surface energy. The degree of conversion of the samples was obtained by FTIR analysis and pendulum hardness was measured using a Konig hardness meter. Scratch resistance of cured films was measured by standard scratch measuring pens. The characteristics obtained from AFM analysis showed that rough surface patterns in this system are controlled linearly by changes in the treated nano-particle concentration. The subtraction of surface energy of the cured film was clear and the water contact angle showed a 60% increase with the addition of a fluorinated nano-particle concentration. Surface hardness decreased and scratch resistance increased as the concentration of treated nanoparticles increased, while the final degree of conversion of the film remained unchanged.

UV-cured self-replenishing hydrophobic polymer films

Self-healing functional polymer surfaces, designed with an intrinsic and spontaneous mechanism which replenishes the damaged surfaces with the original chemical functionalities, are of great interest to maintain a high performance of the functionality and extend the life-time of materials.We report self-replenishing UV-cured hydrophobic polymer films prepared through the incorporation of methacrylate-terminated perfluorinated-dangling chains into poly(ethylene glycol diacrylate) (PEGDA)-based networks. The films are able to spontaneously and fully self-replenish the surface hydrophobicity, multiple times, upon consecutive intentional damages. The rate of recovery was found to be dependent on the glass transition temperature (Tg) of the networks, which directly correlates to the PEG block length in the PEGDA oligomer used. This study demonstrates that an intrinsic self-replenishing mechanism can be implemented in new network architectures, created rapidly and efficiently by free radical UV-polymerization, which allows preparing self-healing functional polymer films in a faster and eco-friendlier way.

Posters

Self-healing functional polymer surfaces, designed with an intrinsic and spontaneous mechanism which replenishes the damaged surfaces with the original chemical functionalities, are of great interest to maintain a high performance of the functionality and extend the life-time of materials.We report self-replenishing UV-cured hydrophobic polymer films prepared through the incorporation of methacrylate-terminated perfluorinated-dangling chains into poly(ethylene glycol diacrylate) (PEGDA)-based networks. The films are able to spontaneously and fully self-replenish the surface hydrophobicity, multiple times, upon consecutive intentional damages. The rate of recovery was found to be dependent on the glass transition temperature (Tg) of the networks, which directly correlates to the PEG block length in the PEGDA oligomer used. This study demonstrates that an intrinsic self-replenishing mechanism can be implemented in new network architectures, created rapidly and efficiently by free radical UV-polymerization, which allows preparing self-healing functional polymer films in a faster and eco-friendlier way.

Effects of NCO:OH ratio and HEMA on the physicochemical properties of photocurable poly(ester-urethane)methacrylates

A series of UV-curable isophorone diisocyanate-based poly(ester-urethane)methacrylate (IPEUMA) oligomers were synthesized by a two-step polymerization process. The amount of isophorone diisocyanate was varied during the synthesis. The effects of NCO:OH ratio and HEMA on the structural and physicochemical properties of UV-cured IPEUMAs were investigated. As the NCO:OH ratio increased, the tensile strength and thermal stability increased, whereas the elongation and hydrolytic degradation of the film decreased. The higher strength and thermal stability for higher NCO:OH ratio may be due to the increase in intermolecular hydrogen bonding in the UV-cured film. UV-cured IPEUMA films also show excellent chemical and solvent resistance.

Synthesis and characterization of photosensitive-fluorosilicone–urethane acrylate prepolymers

Two kinds of novel photosensitive-fluorosilicone–urethane acrylate prepolymers (Si-F15-IPDI-HEA/Si-F6-IPDI-HEA) were synthesized and characterized. Si-F15-IPDI-HEA and Si-F6-IPDI-HEA were able to form homogeneous mixtures with a number of acrylate monomers. Formulations with these prepolymers with common acrylic monomers exhibited high-polymerization rates and final double-bond conversion over 90% after irradiation for 60 s. It was found the final conversion decreased with the increase of the functionality of the monomer. The influence of the monomer and prepolymers on the properties of the UV-cured films was systematically studied. Thermostability property along with mechanical performance was improved with the increase of the functionality of monomers and prepolymers. A decrease of water absorption was also observed through water contact angle measurements. The UV-cured films of Si-F15-IPDI-HEA and Si-F6-IPDI-HEA possessed an excellent adhesion on the PU and PVC leather, providing a potential application in leather industry as a finishing and coating agent.

Diffusion limited behaviour of hydrophobised thin UV-curable nanocomposite coatings against model electrolyte

Two different approaches were used to modify a UV-curing resin based on polyester chemistry, namely molecular and nano-particular approaches. In the molecular approach a hydrophobic compound, glycidyl neodecanoate, was reacted with the resin and was fixed on the polymer backbone. In the nano-particular approach a nano-clay was used to modify the resin in a physical manner. The electrochemical properties of the coating films were investigated using electrochemical impedance spectroscopy. In all cases a broadening of the complex plane graph in the direction of real impedance axis was observed. It was necessary in all cases to incorporate a finite length warburg element into the equivalent circuit to account for this broadening effect. The presence of this element was attributed to an intermediate case of anomalous diffusion of charge carriers through the dense polymeric network of the UV-cured films. EIS investigations of the UV-cured films show that both molecular and nano-particular modifications cause the electrochemical properties of the film to remain constant for a longer immersion time compared to unmodified resin.

Synthesis of a novel UV-curable oligmer 1,4-cyclohexanedimethanol glycidyl ether acrylate and study on its UV-curing properties

A novel UV-curable oligmer 1,4-cyclohexanedimethanol glycidyl ether acrylate (CHDMGEA) was synthesized by utilizing 1,4-cyclohexanedimethanol glycidyl ether (CHDMGE) and acrylic acid (AA) as starting materials, triphenyl phosphine as catalyst and p-hydroxyanisole as inhibitor. The optimum synthetic conditions were that the concentration of triphenyl phosphine was 0.90% of reactants by weight, the concentration of p-hydroxyanisole was 0.20% of reactants by weight, the reaction temperature was 90–100 °C, and the molar ratio of CHDMGE to AA was 0.5:1.1. The experimental results show that CHDMGEA is a kind of good UV-curable oligmer. The impact resistance of the UV-cured films with CHDMGEA as oligmer to prepare UV-curing coating was superior to that of the UV-cured films with bisphenol A diglycidyl ether diacrylate (BPGEA) as oligmer to prepare UV-curing coating.

Biobased reactive diluent for UV-curable urethane acrylate oligomers for wood coating

Castor oil (CO)-based reactive diluent for UV-curable urethane acrylate oligomers was synthesized by the reaction of a CO with diethanolamine and the resultant product was subsequently reacted with allyl chloroformate. The reactive diluent was characterized by FTIR and 1H NMR techniques. This reactive diluent was incorporated in a urethane acrylate oligomer and photoinitiator at different weight fractions varying from 5 to 25 wt% for UV curing. The effects of reactive diluent concentrations on the viscosity of the formulations along with mechanical, chemical, and optical properties of UV-curable coatings were studied. Furthermore, the cured films were evaluated for glass transition temperature (Tg) determined by differential scanning calorimetry and thermal stability by thermogravimetric analysis. Gel content and water absorption of UV-cured films were evaluated.

Effect of different photoinitiators on the properties of UV-cured electromagnetic shielding composites

Abstract A series of UV-cured electromagnetic shielding composites (UV-EMSC) containing different content of graphene oxide (GO) were prepared with oligomer, acrylate active diluents and different photoinitiators (Darocur 1173, Irgacure 184 or Irgacure 651). To fabricate conductive oligomer with low resistivity, polyurethane-acrylate (PUA) was used as the polymer matrix to help construct two-dimensional conductive networks consisting of GO. For forming conductive network structure, the surface functional groups (-OH, -COOH) of GO served as slightly conductive particles bonded with -NCO from the chain of polyurethane. The UV-EMSC exhibited a low resistivity of approximately 402 Ω·cm and an outstanding enhanced electrical conductivity of 249 mS/m at a GO content of 0.0200%. The effects of different photoinitiators on the properties of UV-cured films were investigated. The results indicate that the prepared UV-EMSC has great potential applications in different regions, such as in coatings of electronic, electrical, communications, plastic coatings and wood finishes.

Diisocyanate free and melt polycondensation preparation of bio-based unsaturated poly(ester-urethane)s and their properties as UV curable coating materials

This paper reported the synthesis of bio-based unsaturated poly(ester-urethane)s via a nonisocyanate route, by metal-catalyzed melt polycondensation of itaconic acid with urethanediols. Three novel types of bio-based unsaturated poly(ester-urethane)s, namely, poly(urethanediol 2-itaconic acid), poly(urethanediol 4-itaconic acid) and poly(urethanediol 6-itaconic acid) (poly(U2-IA), poly(U4-IA) and poly (U6-IA) for short code, respectively), were prepared by a green synthetic route. The urethane linkage was formed by the reaction of two equivalent of ethylene carbonate with 1,6-hexanediamine, 1,4-butanediamine and 1,2-ethanediamine to form urethanediols. The urethanediols underwent polymerization with itaconic acid (IA) in the presence of metal catalyst dibutyltin dilaurate (DBTL) to produce low-molecular-weight bio-based unsaturated polyurethanes. Then, these bio-based unsaturated poly(ester-urethane)s were formulated with free radical photoinitiator and curing promoter to prepare UV curable polyurethane systems. After UV curing, the tensile properties, thermal properties and general coating properties of the three UV-cured polyurethane films were similar to that of UV cured polyurethane films prepared by polyurethane-acrylate (PUA). The results suggested that the obtained bio-based unsaturated polyurethanes could serve as coating materials.

Preparation of nanocomposites by swelling of a UV cured cycloaliphatic epoxy film in a silica precursor

In this work, nano composites were prepared from a UV cured cycloaliphatic epoxy resin by swelling the cured film in tetramethoxysilane (TMOS) followed by exposure to humid atmosphere at an elevated temperature. The flexibility of the resin was tuned by using different modifiers, namely hexanediol-diglycidylether (HDGE) and a diglycidoxy terminated polydimethylsiloxane (GTMQ). Glycidoxypropyl trimethoxysilane (GPTS) was also added to the UV-curable mixture in order to promote the swelling of the cured films in TMOS, thus obtaining the silica phases through a sol–gel approach. The swelling was performed at different temperatures (40 and 80 °C); the subsequent hydrolysis and condensation reactions were carried out in dry and humid atmospheres at 80 °C. The obtained films were investigated through DSC and TGA analyses; their submicro- nano- morphology was assessed by SEM. The UV-cured films showed silica rich surfaces, the morphology of which was related to the presence of GPTS and of the reactive comonomers and to the experimental conditions adopted for the sol–gel process. The TMOS absorption and hence the subsequent hydrolysis-condensation processes seem to occur at the surfaces of the films probably due to the selective migration of the silicone chains towards the air interface. The pencil scratch hardness values too were found to increase after the sol–gel treatment on the films.

Synthesis of Poly(methylene oxy-alt PPO)glycols and Its Effect on the Properties of Polyurethane UV-Cured Film

In this study, we synthesized MPPG including the methylene-oxy group from polypropylene glycol (PPG) with the molecular weight (g/mol) of 200. Also UV curable resins were prepared from the mixture of polyurethane acrylate (PUA) oligomer which was synthesized with synthesized MPPG, TMPTA, HDDA, and HP-8 to investigate the possibility of its application for optical film materials. The Tg was higher for UAMP oligomer with MPPG as well as MPPG than that of PPG and UAP oligomer. The refractive index and the pencil hardness of UCM were higher than those of UC while the optical transmittances of UCM and UC were much the same.

Microstructure and electrical property of epoxy/graphene/MWCNT hybrid composite films manufactured by UV-curing

UV-cured epoxy hybrid composite films were manufactured by efficient and facile cationic photochemical polymerization of 3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate mixtures including 5.0 wt% carbon nanofillers of different graphene/multi-walled carbon nanotube (MWCNT) compositions of 10/0, 9/1, 7/3, 5/5, 3/7, and 0/10 by weight ratio. TEM images confirmed that the mixed carbon nanofillers of graphene and MWCNT were well dispersed in the UV-cured epoxy matrix, while MWCNT as a single carbon nanofiller component was aggregated in the matrix. The electrical resistivity of the composite films was thus varied with the increment of the relative MWCNT content in 5.0 wt% carbon nanofillers, i.e., ∼160 Ωcm for the epoxy/graphene composite film, 30∼80 Ωcm for the epoxy/graphene/MWCNT composite films, and ∼16,200 Ωcm for the epoxy/MWCNT composite film. The decreased electrical resistivity of the epoxy/graphene/MWCNT composite films was associated with the interconnected network formation of graphene sheets and MWCNTs. Thus the UV-cured epoxy/graphene and epoxy/graphene/MWCNT composite films exhibited excellent electric heating performance in terms of rapid temperature response, stable maximum temperature, and high electric power efficiency. In addition, the UV-cured epoxy hybrid composite films as electric heating materials were found to be thermally stable up to ∼290 °C.

Toward UV-curable urethane acrylate/silica hybrid coatings: Introducing urethane methacrylate trimethoxysilane (UAMS) as organic–inorganic coupling agent

Urethane methacrylate trimethoxysilane (UAMS) organic–inorganic material was synthesized by the reaction of isophorone diisocyanate with hydroxyethyl methacrylate and aminopropyltrimethoxysilane. This precursor was then added to urethane trimethacrylate (UTMA); consequently, silica domains were appeared within the resulting ultraviolet (UV)-irradiated hybrid coatings. The sol–gel precursors having different amounts of UAMS as well as the UV-irradiated nanocomposite specimens were thoroughly characterized by FTIR, 1H NMR, 13C NMR, SEM, and TGA. The results provided support for the fact that thermo-mechanical properties of hybrid coatings were enhanced markedly by the incorporation of UAMS. This can be explained by the generation of Si–O–Si hard segments throughout the UV-cured films. Study on hardness and thermal stability behavior provided further evidences for the action of UAMS as coupling agent. Noticeably, thermal stability of hybrid coatings experienced an upward trend with the UAMS content, which can be inferred on the basis of strict restrictions on the mobility of polymer chains imposed by the crosslinked network.