UV-curable Polyurethane Acrylate Research Articles

Characteristics of Sonar Encapsulant Materials Fabricated from Electron-Beam-Irradiated Polyurethane Elastomers Coated with UV-Curable Polyurethane Acrylates

The use of thermoplastic polyurethane (TPU) elastomers as encapsulant materials for undersea sonar devices is frequently limited because they do not satisfy the stringent requirements for undersea use. To develop desirable polymeric materials having lower swelling ratios in paraffin oil and seawater than TPU, as well as better mechanical strength, we produced encapsulant materials composed of cross-linked TPU and a coating layer prepared from polyurethane acrylate (PUA) oligomers cured using ultraviolet (UV) irradiation. The electron-beam irradiation of the TPU was adapted to fabricate cross-linked TPU. The encapsulant materials developed in this study exhibited a higher tensile strength and lower swelling ratio than standard TPUs. Reduction in the swelling ratio of the former reached up to 95% of the latter after being impregnated with seawater. Changes in the tensile strength of the former with seawater impregnation were negligible.

Tunable pore size micro/submicron-sieve membranes by soft lithography

Membrane filtration is widely used for advanced water and wastewater treatments because of many favorable features it offers. Critical issues in membrane processes are membrane fouling as well as tortuous and broad size distribution of membrane pores. In this study, micro- and submicron-sieve membranes with uniform, non-tortuous pores were fabricated using a soft-lithographic technique. Due to the precisely controlled pore size, spatial distribution and non-tortuous quality, the membrane flux per surface porosity was shown to be greatly enhanced in comparison with conventional membranes with a tortuous pore structure. Furthermore, the solventless UV-curable polyurethane acrylate (PUA), employed as the membrane material, has lower surface energy leading to much better anti-biofouling performance than other commercial membrane materials. The soft-lithographic technique and UV-curable polyurethane acrylate (PUA) introduced here would open a horizon to a new generation of membranes with anti-fouling capability.

Synthesis of fluorinated urethane acrylate based UV-curable coatings

In the present work fluorinated urethane-acrylate (FUA) monomer was firstly prepared based on isophorone diisocyanate (IPDI), 3,5-bis(perfluorobenzyl)oxy benzyl alcohol (FOH) and 2-hydroxyethyl methacrylate (HEMA) via in situ method. The obtained novel fluorinated urethane-acrylate was characterized by 1H NMR spectroscopy and Fourier Transform Infrared (FT-IR) spectroscopy. The UV-curable polyurethane-acrylate (UV-PUA) formulation was prepared with oligomers, polyurethane-acrylate (PUA) or epoxy acrylate (EA), monomers (FUA, HDDA and TPGDA) and photoinitiator, Darocur 1173. UV-curable clear coatings were applied on plexiglass and teflon substrates. The physical and mechanical properties of UV-cured coatings such as gel content, solvent resistance, hardness, gloss, flexibility and tensile tests were examined. Also thermal degradation behavior of coatings was also evaluated by thermogravimetric (TGA) analysis. Contact angle measurements of water and ethylene glycol on films of coatings have shown that the addition of fluorinated polyurethane-acrylate precursor to the system improved the water repellency and increased the contact angle from 72° to 104°.

Synthesis and Curing Kinetics of UV-Curable Waterborne Bisphenol-S Epoxy Acrylate/Polyurethane-Acrylate Coating

In ouder to prepare the waterborne UV-curable polyurethane acrylate coatings, the anionic polyurethane acrylate emulsifier and bisphenol-S eopxy acrylate were synthesized. The curing process, kinetics and properties of waterborone UV-curable epoxy acrylate/polyurethanes acrylate coating were investigated by FTIR, DSC and DMA. The results show that the static initial curing temperature Ti is 52.36 oC, peak temperature Tp is 71.58 oC, the finished temperature Tf is 89.15 oC. The curing reaction can be described by two-parameter autocatalytic Šesták-Berggren (S-B) model.This coating has a better UV-curing property. The dynamic mechanical analysis showed that the glass transition temperature Tg of coating film is 52.70 oC.

Fabrication of a Polyurethane Acrylate/Polyimide-Based Polymer Mold for a Hot Embossing Process

A high-thermal-resistance polymer-based flexible imprint mold was developed to be used in a hot embossing process. This mold was readily replicated in a UV curing imprint process and can be used as a mold for hot embossing and thermally curing imprint processes. The nano-sized pattern of this mold was not degraded by soaking at 350 degrees C for 10 min and the pattern fidelity was maintained after 10 separate cyclic heating tests between 0 degrees C and 350 degrees C. The substrate of this flexible mold was PI film, and a UV-cured polyurethane acrylate (PUA) layer was used to form the nano-scale patterns. The durability of this polymeric mold was tested by repetitive hot embossing processes. Nano-scale patterns of the mold were readily transferred to a PMMA layer coated onto a Si substrate by hot embossing lithography at 180 degrees C. After 10 cycles of hot embossing processes, no damage or degradation was observed in the flexible polymer mold. Using this polymer mold, patterns as small as 50 nm were successfully transferred to a Si substrate. Due to the flexibility of the polymer mold, nano-scale patterns were successfully transferred to a non-flat acryl substrate by hot embossing lithography.

Synthesis and properties of UV curable polyurethane acrylates based on two different hydroxyethyl acrylates

Two kinds of UV curable polyurethane acrylate oligomers (PUPA and PUCA) were synthesized via the addition reaction between isophorone diisocyanate (IPDI) and polyethylene glycol monoacrylate (PEA6) or polycaprolactone modified hydroxyethyl acrylate (PCLA2). The structures of PUPA and PUCA were characterized by Fourier transform infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC) and differential scanning calorimeter (DSC), and the thermal stability and dynamic mechanical thermal properties of their cured films were measured by thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA), respectively. The viscosity of the oligomers and mechanical properties of the cured films were also studied. The results show that both oligomers have narrow molecular weight distribution. The viscosity of PUPA is 2.310 Pa·s at 25 °C, while that of PUCA is up to 3.980 Pa·s. The UV cured PUPA and PUCA films have homogeneous phase structure, and the PUCA film shows higher glass transition temperature and storage modulus. Furthermore, the PUCA film possesses better mechanical properties than PUPA, while the latter shows better alkali resistance.

Precise tip shape transformation of nanopillars for enhanced dry adhesion strength

We present a simple, yet robust, technique for controlling the tip geometry of nanopillars by utilizing a two-step process of partial photopolymerization of UV-curable polyurethane acrylate (PUA) resin and subsequent tip shape modification. With this technique, head structures of nanopillars were precisely transformed from hemispherical to protruding, mushroom-like tips without any loss in structural integrity of the nanopillars. Nanoscopic and macroscopic adhesion measurements for angled nanopillars with modified tips demonstrated that mushroom-like structures fabricated by our approach could greatly enhance adhesion strengths as compared to unmodified, round head structures. Also, directional adhesion characteristics of angled nanopillars were maintained regardless of tip shapes.

UV-curable waterborne polyurethane-acrylate: preparation, characterization and properties

The waterborne polyurethane-acrylate (PUA) oligomer was firstly prepared based on isophorone diisocyanate (IPDI), polyether polyol (NJ-210), dimethylol propionic acid (DMPA) and hydroxyethyl methyl acrylate (HEMA) via in situ and anionic self-emulsifying method. The UV-curable polyurethane-acrylate (UV-PUA) was obtained with oligomer, monomers (BA and TPGDA) and photoinitiator Darocur 1173. FT-IR, DSC and TGA were employed to investigate the structures and thermal properties of the UV-PUA films. The effects of BA/TPGDA ( R) value, the content of Darocur 1173 and the UV curing time on the performances were investigated. Some mechanical performances, solvent resistance and the gel content of UV-PUA films were measured. When the ratio of BA/TPGDA was 5/5, the UV-PUA film had the best solvent (water, alkali and ethanol) resistances. Besides, with the ratio of the BA/TPGDA increasing, the surface drying time increased. When the content of Darocur 1173 was 4%, the gel content achieved the maximum while the surface drying time achieved the minimum. The obtained UV-curable polyurethane-acrylates are promising as oligomers for UV-curable coatings, plastics, inks and adhesives.

Synthesis and characterization of novel UV-Curable PU-Si hybrids: Influence of silica on thermal, mechanical, and water sorption properties of polyurethane acrylates

Organic-inorganic hybrid membranes (HM1-HM4) were synthesized by incorporating 3 wt% (HM1), 5 wt% (HM2), 10 wt% (HM3), and 20 wt% (HM4) of silica precursors into UV-curable polyurethane acrylate (PU) matrix using sol-gel technique. PU, which was prepared by reacting polycaprolactone triol (PCLT) and isophorone diisocyanate (IPDI), was used as the starting organic polymer whereas tetraethoxysilane (TEOS) was used as a precursor for the development of the inorganic phase. The completion of the polymerization reaction of PU and the synthesis of hybrid membranes were confirmed by Fourier transform infrared spectroscopy (FTIR) whereas the morphology was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The thermal, mechanical, and anti-water sorption properties of the hybrid membranes were examined by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), nanoindentator and thin film diffusion analysis, which revealed that HM2 has the highest thermal, mechanical, and anti-water sorption properties. TGA demonstrated that the thermal decomposition temperature (T d10%) of HM2 increased significantly, being 30 °C higher than that of pure PU, whereas DSC indicated that the introduction of 5 wt% of TEOS increased the glass transition temperature from 93.8 to 103 °C. Accordingly, the mechanical and water sorption properties were also enhanced greatly as evidenced by nanoindentation analysis and anti-water sorption data, in which HM2 shows the highest elastic modulus (8.354 GPa), hardness (0.262 GPa), and lowest water sorption capacity. These thermal, mechanical, and anti-water sorption improvements are important for the practical process and applications of PU.

Synthesis and characterization of novel UV-curable polyurethane–clay nanohybrid: Influence of organically modified layered silicates on the properties of polyurethane

Nanohybrids based on UV-curable polyurethane acrylate (PU) and cloisite 20B (C-20B) have been synthesized by solution blending method using different loading levels of C-20B. The structures of PU/C-20B nanohybrids were confirmed by Fourier transform infrared spectroscopy (FTIR) while X-ray diffraction and transmission electron microscopy (TEM) showed the intercalation of PU into layer silicates. The thermal properties of PU and PU/C-20B nanohybrids were investigated by thermal gravimetric analysis (TGA) and differential scanning calorimetric (DSC). TGA tests revealed that the thermal decomposition temperature ( T d10%) of the nanohybrid containing 5 wt% of C-20B increased significantly, being 61 °C higher than that of pure PU while DSC measurements indicated that the introduction of 5 wt% of clay increased the glass transition temperature from 89.7 to 101 °C. Accordingly, the mechanical and anti-water absorption properties proved also to be enhanced greatly as evidenced by nanoindentation anylsis and water absorptions data in which the nanohybrid containing 5 wt% of clay have highest elastic modulus (4.508 GPa), hardness (0.230 GPa) and lowest water absorption capacity. Thus the formations of nanohybrids manifests through the enhancement of thermal, mechanical and anti-water absorption properties as compared with neat PU due to the nanometer-sized dispersion of layered silicate in polymer matrix.

Special susceptive aqueous ammonia chemi-sensor: Extended applications of novel UV-curable polyurethane-clay nanohybrid

In this contribution, chemical sensor for the detection of aqueous ammonia has been fabricated using UV-curable polyurethane acrylate (PU) and nanohybrids (NH-1, NH-3 and NH-5). PU has been prepared by reacting polycaprolactone triol (PCLT) and isophorone diisocyanate (IPDI) while the nanohybrids, NH-1, NH-3, and NH-5 have been synthesized by solution blending method using PU with 1, 3, and 5wt% loading levels of C-20B. PU and their nanohybrids showed higher sensitivity investigated by I–V technique using aqueous ammonia as a target chemical. All the nanohybrids showed higher sensitivity as compared to neat PU. The sensitivity increased with increase in clay content and the nanohybrid containing 5wt% of clay showed the highest sensitivity (8.5254μAcm−2mM−1) with the limit of detection (LOD) of 0.0175±0.001μM, being 7.8 times higher than pure PU. The calibration plot for all the sensors was linear over the large range of 0.05μM to 0.05M. The response time of the fabricated sensor was <10.0s. Therefore, one can fabricate efficient aqueous ammonia sensor by utilization of nanohybrid as an efficient electron mediator.

Blending Property of Water-Based UV-Curable Polyurethane Acrylate and Epoxy Acrylate

Water-based UV-curable prepolymers are novel environmentally friendly materials. The blending property of two kinds of the prepolymers, water-based UV-curable polyurethane acrylate (UVPU) and water-based UV-curable epoxy acrylate (WEA), was studied in this paper. Blending compatibility, curing rate, optical and mechanical properties, and the cross-section morphology of the cured films of UVPU and WEA were investigated by Fourier transform infrared (FTIR), UV-visible spectrophotometer (UV-vis) and Environmental scanning electron microscopy (ESEM). Results indicated that the two prepolymers had good blending compatibility and high curing rate under UV radiation. The elongation at break of the cured film by WEA mixed with 20 wt% UVPU had 1.5 times increase compared to pure WEA, and the gloss increased 23% compared to pure UVPU, but the tensile strength decreased slightly. The morphology showed that the molecules of the two prepolymers polymerized each other and formed a network similar to the structure of Interpenetrating Polymer Networks (IPN). The comprehensive properties of the film were improved by blending of WEA and UVPU, and could be widely applied in the fields of coating varnish or printing ink.

The Study of Several UV Curable Polyurethane Acrylates

In this paper, several UV curable polyurethane acrylates were synthesized by using isophorone diisocyanate(IPDI), polyethylene glycol(PEG) , Dipropylene Glycol Diacrylate (DPGDA), trimethylolpropane triacrylate (TMPTA), and hydroxyethyl acrylate(HEA) as the raw materials and dibutyltin dilaurate(DBTDL) as the catalyst. The structure was confirmed by the Fourier transform infrared spectroscopy (FTIR). The characterization showed the coatings have a good property.

폴리우레탄 디아크릴레이트의 미세다공성 UV코팅에 의한 PET 직물의 투습방수가공

Breathable waterproof PET fabrics were prepared by the UV coating of UV-curable polyurethaneacrylate(PUA) formulation mixed with polyethyleneglycol(PEG) as a water soluble pore former. The dispersed PEG in the UV-cured coating was extracted by warm water, which can generate individual circular pores uniformly distributed all over the coating instead of pore channels. Accordingly the moisture permeability of the microporously coated fabrics increased substantially with increasing PEG addition without significant reduction of hydrostatic pressure. Also the silicone diacrylate addition in the formulation was beneficial in increasing the hydrostatic pressure. The UV-based microporous coating can be an alternative to conventional thermal curing of solventborne polyurethane coating owing to the enhanced environment friendliness and energy saving.

Fabrication of Antireflection and Antifogging Polymer Sheet by Partial Photopolymerization and Dry Etching

We present a simple method to fabricate a polymer optical sheet with antireflection and antifogging properties. The method consists of two consecutive steps: photocross-linking of UV-curable polyurethane acrylate (PUA) resin and reactive ion etching (RIE). During photopolymerization, the cured PUA film is divided into two domains of randomly distributed macromers and oligomers due to a relatively short exposure time of 20 s at ambient conditions. Using the macromer domain as an etch-mask, dry etching was subsequently carried out to remove the oligomer domain, leaving behind a nanoturf surface with tunable roughness. UV-vis spectroscopy measurements demonstrate that transmittance of a nanoturf surface is enhanced up to 92.5% as compared to a flat PUA surface (89.5%). In addition, measurements of contact angle (CA) reveal that the etched surface shows superhydrophilicity with a CA as small as 5 degrees. To seek potential applications, I-V characteristics of a thin film organic solar cell were measured under various testing conditions. It is shown that the efficiency can be increased to 2.9% when a nanoturf film with the surface roughness of 34.73 nm is attached to indium tin oxide (ITO) glass. More importantly, the performance is maintained even in the presence of water owing to superhydrophilic nature of the film.

Thermal properties and flame retardancy of an ether-type UV-cured polyurethane coating

A new UV-reactive monomer piperazine-N,N'-bis(acryloxyethylaryl-phosphoramidate) (N-PBAAP) containing phosphorus and nitrogen was synthesized and used as flame retardant for an ether-type UV-cured polyurethane acrylate (PUA) coating. The thermal properties of the PUA films were investigated by thermogravimetric analysis (TGA) in air and nitrogen atmosphere. The TGA results showed that the incorporation of N-PBAAP can obviously enhance the char residue of the PUA coatings. From the TGA and real time Fourier transformed infrared spectroscopy (RT-FTIR) results, different degradation behaviors were observed in the PUA coatings with different N-PBAAP content. The combustibility of the PUA coatings was evaluated by microscale combustion calorimeter (MCC). The MCC results revealed that the addition of N- PBAAP in the coatings can significantly reduce the peak Heat Release Rate (pHRR), Heat Release Capacity (HRC) and the Total Heat Release (THR) of the samples. Furthermore, dynamical mechanical thermal analysis (DMA) was employed to examine the viscoelastic properties of the PUA films. It was found that the incorporation of N-PBAAP in the formulation can bring in more functional groups to the coatings, which results in an increase of the glass transition temperature (Tg) and cross linking density (XLD) of the films.

SYNTHESIS AND PROPERTIES OF UV/MOISTURE DUAL CURABLE HYPERBRANCHED POLYURETHANE COATINGS

Hyperbranched polyurethane(HPU) was synthesized from toluene-2,4-diisocyanate(TDI) and diethanolamine(DEOA) by one-step method,which was further modified to prepare UV-curable hyperbranched polyurethane acrylate(UV-HPUA) and a series of dual curable hyperbranched polyurethane acrylate(DHPUA) with different ratios of acrylate and trimethoxysilane end groups.All resins were characterized by Fourior-transformed infrared spectroscopy(FTIR),~1H and()~(13)C nuclear magnetic resonance(~1H-?()~(13)C-NMR) and gel permeation chromatography(GPC).Then the resins were used as oligomers to prepare UV/moisture dual curable coatings.The surface topographies of the UV cured coatings were investigated by atomic force microscopy(AFM) before and after moisture cure.The results showed that the superficial degree of roughness of the coatings,with acrylate and trimethoxysilane end groups ratio 3～1 or 1～1,decreased after moisture cure.However,UV-HPUA and acrylate and trimethoxysilane end groups ratio 1～3 coatings increased after moisture cure.Thermal gravimetric analysis(TGA) results indicated that the coating thermal stability increased with increasing trimethoxysilane end groups.Moreover the physical properties of the UV cured coating were also measured before and after moisture cure,which indicated that physical properties of the UV-HPUA coating were slight improved through moisture curing process.However,the physical properties were greatly improved for DHPUA coatings,the pencil hardness increased from 6B to 3H and 4H.

Synthesis and properties of novel polyurethane acrylate containing 3-(2-hydroxyethyl) isocyanurate segment

Novel UV curable multi-functional polyurethane acrylate (PUA) containing 3-(2-hydroxyethyl) isocyanurate (THEIC) segment was synthesized through three step reactions, the ring-opened reaction of ɛ-caprolactone with THEIC under the catalysis of tetrabutyl titanate (TBT), the polyaddition reaction between formed hydroxyl compounds and isophorone diisocyanate (IPDI) and condensation reaction between the product of the second step and pentaerythritol triacrylate (PETA). The chemical structure of PUA oligomer and some influence factors in synthesis process were characterized with GPC, 1H NMR and FTIR. And its photopolymerization process and properties of cured films were also investigated.

Reliability analysis of transparent conductive tracks embossed in ZnO and Al-ZnO sol–gel materials

In this paper, we present a low-cost rapid replication approach to fabricate ZnO and Al-doped ZnO Transparent Conductive Oxide electrode structures using both hard UV curable polyurethane acrylate and soft thermal curable polydimethylsiloxane moulds. The thin films of the ZnO and Al-ZnO sol–gel precursor solution prepared from zinc acetate monoethanolamine and isopropanol were cast into a polydimethylsiloxane or polyurethane acrylate mould containing the electrode design. For soft mould embossing, the sol–gel coated substrate and polydimethylsiloxane mould were dried under vacuum at 70 °C for 3h. While for hard mould embossing, the system was heated at 150 °C for 30 min with 100 N applying force and then demoulded at 80 °C. The formed electrode patterns can be further densified or annealed giving a stable film that retains the embossed shape. The difference of surface profile obtained by soft and hard moulding is detailed and the hard mould is shown to be more suitable for low aspect ratio conductors. And the reliability study on embossed ZnO and Al-ZnO conductive tracks prepared with hard moulds shows that the embossed structure still retains good quality.

UV curable polyurethane acrylate coatings for metal surfaces

Purpose – The purpose of this paper is to synthesise environment friendly UV curable polyurethane acrylate resins for various industrial applications and study the performance properties of the cured coating films applied over metal surfaces.Design/methodology/approach – The polyurethane acrylate resin was synthesised using polyester polyol (synthesised using ethylene glycol, adipic acid and 1,6 hexane diol), isophorone diisocynate (IPDI) and 2‐hydroxy ethyl methacrylate (HEMA). The different formulations were developed using various reactive diluents viz. monofunctional, difunctional, trifunctional and tetrafunctional (ethoxylated phenol monoacrylate, 1, 6 hexane diol di acrylate, dipropylene glycol di acrylate, trimethylol propane triacrylate, propoxylated trimethylol propane triacrylate, pentaerythrol triacrylate – PETA). These samples were cured under UV radiation. For effective curing, various compositions of oligomers, photoinitiator and reactive diluents were used. The mechanical, optical, rheologi...