Degree Of Double Bond Conversion Research Articles

Photopolymer-Based Composite with Substance Release Capability Manufactured Additively with DLP Method.

In this study, caffeine-loaded photoresin composites with homogeneous structures, suitable for additive manufacturing of transdermal microneedle systems, were obtained. The properties of the composites with varying caffeine concentrations (0.1-0.4% w/w) were investigated for carbon-carbon double bond conversion using Fourier Transform Infrared Spectroscopy, surface wettability and mechanical properties using a static tensile test and nanoindentation, and caffeine release in ethanol using UV-Vis. The caffeine concentration did not affect the final degree of double bond conversion, which was confirmed in tensile tests, where the strength and Young's modulus of caffeine-loaded samples had comparable values to control ones. Samples with 0.1 and 0.2% caffeine content showed an increase in nanohardness and reduced elastic modulus of 50 MPa and 1.5 MPa, respectively. The good wettability of the samples with water and the increase in surface energy is a favorable aspect for the dedicated application of the obtained composite materials. The amount of caffeine released into the ethanol solution at 1, 3 and 7 days reached a maximum value of 81%, was higher for the lower concentration of caffeine in the sample and increased over time. The conducted research may enhance the potential application of composite materials obtained through the digital light processing method in additive manufacturing.

Evaluation of flexible three-dimensionally printed occlusal splint materials: An in vitro study.

To evaluate and compare the mechanical properties, water sorption, water solubility, and degree of double bond conversion of three different commercially available three-dimensional (3D) printing resins used for the fabrication of flexible occlusal splints. A digital printer was used to generate specimens from the evaluated splint materials (KeySplint Soft, IMPRIMO LC Splint flex, and V-Print splint comfort). The specimens were equally divided and tested either dry or after water storage at 37°C for 30 days. A three-point bending test was used to assess flexural strength, elastic modulus, and fracture toughness. A two-body wear test was performed using a dual-axis chewing simulator. Water sorption and water solubility were measured after 30 days. The degree of double bond conversion was determined by FTIR-spectrometry. All data for the evaluated properties were collected and statistically analyzed. Both material and storage conditions had a significant effect on the flexural strength (P<0.001), elastic modulus (P<0.001), fracture toughness (P<0.001), and wear (P<0.001). The highest water sorption was noticed with IMPRIMO LC Splint flex (1.9±0.0 %), while V-Print splint comfort displayed the lowest water solubility (0.2±0.0 %). For the degree of conversion, it was statistically non-significant among the different materials (P=0.087). Different flexible 3D-printed splints available in the market displayed variations in the evaluated properties and clinicians should consider these differences when choosing occlusal device materials. Among the tested flexible splint materials, KeySplint Soft had the greatest flexural strength, elastic modulus, fracture toughness, wear resistance, and degree of conversion. It also showed the lowest water sorption.

Synthesis and properties of acyldiphenylphosphine oxides photoinitiators carrying ferrocene group for free radical photopolymerization

Thick film curing has become a research hotspot in photocuring systems, among which designing and synthesizing visible light initiators is particularly important. Herein, two new visible light initiators of (diphenylphosphoryl)(ferrocene-1-yl)methanone (FEPO) and ferrocene-1,1′-diylbis((diphenylphosphoryl)methanone) (FSPO) were designed and synthesized from diphenylphosphine oxide reacting with ferrocenecarboxaldehyde and 1,1′-ferrocenedicarboxaldehyde, respectively. FEPO and FSPO possess good solubility in different solvents and acrylic monomers. The UV-Vis spectrums of FEPO and FSPO showed that they exhibit a wide absorption range of 300–670 nm, and the maximum absorption wavelengths are about 494 nm and 505 nm, with a molar extinction coefficient of around 1226 M⁻¹cm⁻¹ and 299 M⁻¹cm⁻¹, suggesting that they are likely to be visible light photoinitiator (PI). The addition of N-phenylglycine (NPG) significantly improved the curing efficiency of FEPO and FSPO, the degree of double bond conversion (DC) of FSPO increased from 27 % to 48 % under the irradiation of LED@480 nm, while, under the irradiation of LED@405 nm, the DC of FEPO/NPG is about 52 %. Moreover, the curing depth of FEPO/NPG/trimethylolpropane triacrylate (TMPTA) (1.75 cm) was about 1.8 times that of diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide (TPO)/TMPTA (0.98 cm) after irradiating for 5 min. In addition, FEPO can be used in laser cladding deposition (LCD) 3D printers with light-emitting diode (LED)@405 nm. Using steady-state photolysis and electron spin resonance spin-trapping studies, the photocuring mechanism was examined. Additionally, photoinitiators (PIs) also exhibit superior biocompatibility performance demonstrated by cytotoxicity assays, suggesting they might be utilized in 3D printing in biological materials and coatings for food packaging.

Synthesis and Characterization of Dental Nanocomposite Resins Reinforced with Dual Organomodified Silica/Clay Nanofiller Systems.

Quaternary ammonium (QA) compounds have been widely studied as potential disinfectants in dental restorative materials. The present work investigates whether the gradual displacement of nanosilica by QA-clay nanoparticles may have an impact on the physicochemical and mechanical properties of dental nanocomposite resins. For this purpose, Bis-GMA/TEGDMA-based composite resins were initially synthesized by incorporating 3-(trimethoxysilyl)propyl methacrylate (γ-MPS)-modified nanosilica/QA-clay nanoparticles at 60/0, 55/5, 50/10, 40/20, and 30/30 wt% filler loadings. Their structural characterization was performed by means of scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). The degree of double bond conversion (DC) over time and the polymerization shrinkage were determined with Fourier transform infrared spectroscopy (FTIR) and a linear variable displacement transducer (LVDT), respectively. Mechanical properties as well as water sorption and solubility parameters were also evaluated after storage of nanocomposites in water for 7 days at 37 °C. Spectral data revealed intercalated clay configurations along with areas characterized by silica-clay clusters for clay loadings up to 30 wt%. Furthermore, the insertion of 10 wt% QA-clay enhanced the auto-acceleration effect also sustaining the ultimate (DC), reduced the setting contraction and solubility, and, finally, yielded flexural modulus and strength very close to those of the control nanocomposite resin. The acquired results could herald the advanced design of dental restorative materials appropriate for contemporary clinical applications.

Synthesis and properties of acyldiphenylphosphine oxides photoinitiators carrying triphenylamine or pyrene group for free radical photopolymerization

AbstractTwo new photoinitiators of acyldiphenylphosphine oxides carrying triphenylamine (NHPO) or pyrene group (BHPO) were designed and synthesized with diphenylphosphine oxide reacting with 4‐(diphenylamino) benzaldehyde or 1‐pyrenecarboxaldehyde. The solubility of NHPO is about 13.7 wt% in TMPTA, which is higher than that of (2,4,6‐trimethylbenzoyl) diphenylphosphine oxide (TPO) (about 12.5 wt%). The UV–Vis spectrum of NHPO and BHPO revealed that their maximum absorption wavelengths have redshifted to 397 and 419 nm, respectively, with a molar extinction coefficient of around 19,057 and 24,257 M−1 cm−1, suggesting that they are likely to be effective photoinitiators when exposed to light from LEDs. According to real‐time Fourier transform infrared spectroscopies, the degree of double bond conversion of NHPO reached 65%, which was higher than that of TPO (about 45%), showing that NHPO had substantially better photoinitiated properties than TPO. Using steady‐state photolysis and electron spin resonance spin‐trapping studies, the photocuring mechanism was examined, and it was discovered that the NHPO and BHPO had produced two free radicals. Additionally, NHPO exhibited superior biocompatibility performance as demonstrated by cytotoxicity assays and had a low migration rate of only 0.23%, as determined by migration. As a result, NHPO might be utilized in coatings for food packaging.

Evaluation of a biobased polycarbonate interpenetrated network in a dental resin composite

Silanization of filler particles in a dental resin composite is achieved by the formation of Si-O-Si bonds, however, these bonds are especially vulnerable to hydrolysis because this covalent bond has a significant ionic character due to the electronegativity differences between the atoms. The objective of this study was to evaluate the use of an interpenetrated network (IPN) as alternative of silanization reaction and to assess its effect in selected properties of experimental photopolymerizable resin composites. The interpenetrate network was obtained during the photopolymerization reaction of organic matrix (BisGMA/TEGDMA) with a biobased polycarbonate. Its characterization was performed via FTIR, flexural strength, flexural modulus, depth of cure, sorption water and solubility. A resin composite formulated with non-silanized filler particles was used as control. The IPN with a biobased polycarbonate was successfully synthesized. The results showed that the IPN based resin composite had higher values of flexural strength, flexural modulus, and degree of double bond conversion than the control (p < 0.05). Polymerization shrinkage, water sorption and solubility were statistically significantly lower than the control resin (p < 0.05). Finally, this study shows there were no statistically significant differences for the biocompatibility outcomes (p > 0.05). The biobased IPN replaces the silanization reaction in resin composites, improving physical and chemical properties. Therefore, IPN with a biobased polycarbonate could be potentially useful in the formulation of dental resin composites.

Employing NaYF4: Yb, Tm upconversion particles (UCPs) in combination with rGO and PANI nanomaterials for the fabrication of radiation-curable anticorrosion composites/coatings

Upconversion particles (UCPs) able to emit photons from the ultraviolet to near-infrared (NIR) region of the electromagnetic spectrum when excited by a NIR laser may be used as internal radiation sources for the manufacture of thick composites with uniform and deep polymerization. In this work, NaYF4: Yb, Tm-based UCPs were synthesized and employed to cure composites using a dual curing method via UV and blue light produced from the UCPs to activate the photo-initiators (PIs), and the resulting cure depth and degree of double bond conversion (DC) were measured. In addition, the influence of UCP content and laser power on cure depth and DC was investigated. The emission rate of the UCPs demonstrated a non-linear, wavelength-specific relationship with increasing laser power and exposure time. Using optimal conditions, 62 % DC with a 2.5 cm cure depth was achieved. For the first time, the ability of UCPs to cure composites in the presence of reduced graphene oxide (rGO) and polyaniline (PANI) nanoparticles was studied. Results indicated that DC was almost consistent across samples (except the sample containing 1 wt% rGO), although the addition of nanomaterials decreased DC and cure depth. The addition of 0.5–0.5 wt% rGO-PANI increased the nanocomposites' compressive strength and strain at failure by 66 and 37 %, respectively. The nanocomposite formulations were applied to steel and the anti-corrosion properties were also investigated. The findings revealed low-frequency impedance (|Z|10 mHz) numbers higher than 1010 Ω.cm2 up to 4 w immersion duration, proving this coating's exceptional barrier anti-corrosion capabilities.

Influence of Initiator Concentration on the Polymerization Course of Methacrylate Bone Cement.

Background: The amount of oxidant (initiator) and reductant (co-initiator) and their ratio have a significant effect on the properties of polymethacrylate bone cement, such as maximum temperature (Tmax), setting time (tset) and compressive strength (σ). The increase in the initiating system concentration causes an increase in the number of generated radicals and a faster polymerization rate, which shortens the setting time. The influence of the redox-initiating composition on the course of polymerization (rate of polymerization and degree of double bond conversion) and the mechanical properties of bone cement will be analyzed. Methods: Bone cements were synthesized by mixing a powder phase composed of two commercially available methacrylate copolymers (Evonic) and a liquid phase containing 2-hydroxyethyl methacrylate (HEMA), methyl methacrylate (MMA), and triethylene glycol dimethacrylate (D3). As an initiating system, the benzoyl peroxide (BPO) as an oxidant (initiator) in combination with a reducing agent (co-initiator), N,N-dimethylaniline (DMA), was used. Samples were prepared with various amounts of peroxide BPO (0.05%, 0.1%, 0.2%, 0.3%, 0.5% and 0.7% by weight) with a constant amount of reducing agent DMA (0.5 wt.%), and various amounts of DMA (0.25%, 0.35% and 0.5% by weight) with a constant amount of BPO (0.3 wt.%). The polymerization kinetics were studied by differential scanning calorimetry (DSC). Doughing time and compressive strength tests were carried out according to the requirements of the ISO 5833:2002 standard. Results: The increase in polymerization rate was due to the increase in the amount of BPO. In addition, the curing time was shortened, as well as the time needed to achieve the maximum polymerization rate. The final conversion of the double bonds in the studied compositions was in the range 74-100%, and the highest value of this parameter was obtained by the system with 0.3 wt.% of BPO. The doughing times for each BPO concentration were in the range of 90-140 s. The best mechanical properties were obtained for the cement following the initiating system concentrations: 0.3 wt.% of BPO and 0.5 wt.% of DMA. Nevertheless, all tested cements met the requirements of the ISO 5833:2002 standard. Conclusions: Based on the conducted polymerization kinetic studies, the best reaction conditions are provided by an initiating system containing 0.3 wt.% of BPO oxidant (initiator) and 0.5 wt.% of DMA reductant (co-initiator). A decrease in the DMA amount caused a decrease in the polymerization rate and the amount of heat released during the reaction. The change in BPO and DMA concentrations in the composition had little effect on the doughing time of the studied bone cement. The cements showed similar doughing times, ranging from 90-225 s, which is comparable to the bone cement available on the market.

Effect of 3D Printer Type and Use of Protection Gas during Post-Curing on Some Physical Properties of Soft Occlusal Splint Material.

Despite the fact that three-dimensional (3D) printing is frequently used in the manufacturing of occlusal splints, the effects of the 3D printer type and post-curing methods are still unclear. The aim of this study was to investigate the effect of the printer type (digital light processing: DLP; and liquid crystal display: LCD) as well as the post-curing method with two different atmospheric conditions (air and nitrogen gas (N2)) on the mechanical and surface properties of 3D-printed soft-type occlusal splint material. The evaluated properties were flexural strength, flexural modulus, Vickers hardness (VHN), fracture toughness, degree of double bond conversion (DC%), water sorption, water solubility, and 3D microlayer structure. The printer type significantly affected all the evaluated properties. Flexural strength, flexural modulus, and fracture toughness were significantly higher when specimens were printed by a DLP printer, while VHN and DC% were significantly higher, and a smoother surface was noticeably obtained when printed by an LCD printer. The post-curing at an N2 atmosphere significantly enhanced all of the evaluated properties except water sorption, 3D microlayer structure, and fracture toughness. The current results suggested that the printer type and the post-curing methods would have an impact on the mechanical and surface properties of the evaluated material.

Effect of Nitrogen Gas Post-Curing and Printer Type on the Mechanical Properties of 3D-Printed Hard Occlusal Splint Material

Although three-dimensional (3D) printing is clinically convenient to fabricate occlusal splints, it is still unclear how the post-curing method and the printer type can affect 3D-printed splints. This study aimed to evaluate the effect of stroboscopic post-curing at a nitrogen gas (N2) atmosphere versus post-curing in an air atmosphere, as well as the printer type (liquid crystal display (LCD) and digital light processing (DLP)) on the mechanical properties of a 3D-printed hard-type occlusal splint material. Flexural strength, flexural modulus, Vickers hardness number (VHN), fracture toughness, degree of double bond conversion (DC), 3D microlayer structure, water sorption, and water solubility were evaluated. The post-curing method significantly affected all evaluated properties except fracture toughness and 3D microlayer structure, while the printer type significantly affected all evaluated properties except flexural strength and flexural modulus. VHN and DC were significantly higher, and the smoother surface was noticeably obtained when printed by LCD printer and post-cured at an N2 atmosphere. The current results suggested that the post-curing method and the printer type would play a role in the mechanical properties of the evaluated material and that the combination of post-curing at an N2 atmosphere and LCD printer could enhance its mechanical properties and surface smoothness.

Rational design and evaluation of UV curable nano-silver ink applied in highly conductive textile-based electrodes and flexible silver-zinc batteries

• A novel UV curable nano-silver ink with low-temperature and short-time curing features was developed for the application of high-performance e-textiles. • By investigating the influence of ink composition, it can provide a guideline to the ink formulation design and understand the mechanism of printing defect formation. • The electrical conductivity of textile-based electrode was achieved as high as 2.47 × 106 S/m when the nano-silver content of conductive ink was 60 wt%. • The textile-based electrode showed outstanding mechanical durability and could maintain resistance stability within 10 washing and drying cycles. • The application potential of conductive ink in fabricating e-textiles was confirmed by using the textile-based electrode as the cathode of silver-zinc battery. The possibility of printing conductive ink on textiles is progressively researched due to its potential benefits in manufacturing functional wearable electronics and improving wearing comfort. However, few studies have reported the effect of conductive ink formulation on electrodes directly screen-printed on flexible substrates, especially printing UV curable conductive ink on common textiles. In this work, a novel UV curable nano-silver ink with short-time curing and low temperature features was developed to manufacture the fully flexible and washable textile-based electrodes by screen printing. The aim of this study was to determine the influence of ink formulation on UV-curing speed, degree of conversion, morphology and electrical properties of printed electrodes. Besides, the application demonstration was highlighted. The curing speed and adhesion of ink was found depending dominantly on the type of prepolymer and the functionality of monomer, and the type of photoinitiator had a decisive effect on the curing speed, degree of double bond conversion and morphology of printed patterns. The nano-silver content is key to guarantee the suitable screen-printability of conductive ink and therefore the uniformity and high conductivity of textile-based electrodes. Optimally, an ink formulation with 60 wt% nano-silver meets the potential application requirements. The electrode with 1.0 mm width showed significantly high electrical conductivity of 2.47 × 10 6 S/m, outstanding mechanical durability and satisfactory washability. The high-performance of electrodes screen-printed on different fabrics proved the feasibility and utility of UV curable nano-silver ink. In addition, the application potential of the conductive ink in fabricating electronic textiles (e-textiles) was confirmed by using the textile-based electrodes as the cathodes of silver-zinc batteries. We anticipate the developed UV curable conductive ink for screen-printing on textiles can provide a novel design opportunity for flexible and wearable e-textile applications.

Viscosity, Degree of Polymerization, Water Uptake, and Water Solubility Studies on Experimental Dichloro-BisGMA-Based Dental Composites

The objective of this work was to investigate the advantages of using dichloro bisphenol A-glycidyl methacrylate (dCl-BisGMA) as a potential matrix for dental resin composites. A series of model composites containing 65 wt% resin (urethane dimethacrylate/triethylene glycol dimethacrylate/BisGMA as 1:3:1) and 35 wt% silanated silica were prepared. Thus, BisGMA was replaced by dCl-BisGMA as 0, 25, 50, and 100 wt% to obtain UTBC0, UTBC25, UTBC50, and UTBC100, respectively. The composites’ rheological properties, degree of double-bond conversion (DC), water sorption (WSP), and water solubility (WSL) were examined. The data revealed a statistically significant reduction in the complex viscosity of composites containing dCl-BisGMA, compared with UTBC0. No significant differences between DCs were detected (p &lt; 0.05). A significant enhancement in the reduction of the dCl-BisGMA composite WSP was also detected, and conversely, WSL was increased. Although the viscosity, DC, and WSP characters were enhanced, a WSL increase is an undesirable development. However, WSL is supposedly caused by cyclization of small flexible chains, which is more likely to occur in the presence of hydrophobic monomers such as dCl-BisGMA and more prone to leaching than are crosslinked networks. We concluded that dCl-BisGMA is a monomer that could potentially be used as an alternative or in combination with traditional monomers, including BisGMA, in resin-based dental composites, and it deserves further investigation.

Dental composite resins with low polymerization stress based on a new allyl carbonate monomer

The objective of this study was to synthesize a diallyl carbonate monomer, allyl(2-(2-(((allyloxy)carbonyl)oxy)benzoyl)-5-methoxyphenyl) carbonate (BZ-AL), and to evaluate its effect as Bis-GMA diluent in the formulation of photopolymerizable dental composite resins. The chemical structure of BZ-AL monomer was determined by means of H1 NMR, C13 NMR and FTIR spectroscopies. An experimental composite comprising a mixture of Bis-GMA and BZ-AL monomers and silanized inorganic filler was formulated. Experimental material was compared with a control composite formulated with Bis-GMA/TEGDMA. Double bond conversion, polymerization kinetics, volumetric shrinkage, polymerization stress, and flexural properties were investigated. The data were analyzed through a Student t-test (α = 0.05). Flexural strength of the experimental materials with BZ-AL monomer showed a statistically significant increase (p < 0.001). The experimental composite has a lower polymerization rate than the control composite, on the other hand, the experimental composite resin has the highest degree of double bond conversion. There are no differences in the polymerization shrinkage of the composites, however, the polymerization stress of the experimental materials was 50% lower than the control resin. Finally, the cell viability test showed that the experimental resins formulated with the BZ-AL monomer was not cytotoxic. Due to its characteristics, BZ-AL monomer is potentially useful for the formulation of composite materials with applications in dentistry.

Evaluation of dental composites resins formulated with non-toxic monomers derived from catechol

Two liquid monomers (CT-AL and CT-ACR) were synthesized from the acylation of tert-butyl catechol with different acid chlorides. The monomers were used to prepare photopolymerizable dental composite for completely replacing TEGDMA. Properties such as flexural strength, modulus of elasticity, degree of double bond conversion, polymerization shrinkage, as well as the polymerization stress were studied. Also, color alteration, translucency, and cytotoxicity were evaluated. The results show that the experimental materials formulated with CT-AL and CT-ACR have similar mechanical properties to a control material formulated with BisGMA/TEGDMA, similar polymerization shrinkage, and less polymerization stress. The composite formulated with the CT-AL monomer shows a similar degree of conversion (72%), while the composite formulated with the CT-ACR monomer has a degree of conversion lower (58%) than the control resin (71%). These results suggest that both monomers could have potential applications in the formulation of composites for dental restorations.

Synthesis of chemically modified BisGMA analog with low viscosity and potential physical and biological properties for dental resin composite

ObjectivesThe currently available commercial dental resin composites have limitations in use owing to the high viscosity and water sorption of Bisphenol A glycidyl methacrylate (BisGMA). The objective of this study was to obtain a BisGMA analog with reduced viscosity and hydrophilicity for potential use as an alternative to BisGMA in dental resin composites. MethodsThe targeted chlorinated BisGMA (Cl-BisGMA) monomer was synthesized via the Appel reaction. The structural modification was confirmed via 1H- and 13C nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and mass spectrometry. Five resin mixtures (70:30wt.%: F1=BisGMA/TEGDMA; F2=Cl-BisGMA/TEGDMA; F3=Cl-BisGMA only; F4=Cl-BisGMA/BisGMA; F5 contained 15% TEGDMA with equal amounts of BisGMA and Cl-BisGMA) were prepared. The viscosity, degree of double-bond conversion (DC), water sorption (WSP), and solubility (WSL) were tested. Cell viability and live/dead assays, as well as cell attachment and morphology assessments, were applied for cytotoxicity evaluation. ResultsCl-BisGMA was successfully synthesized with the viscosity reduced to 7.22 (Pas) compared to BisGMA (909.93,Pas). Interestingly, the DC of the F2 resin was the highest (70.6%). By the addition of equivalence concentration of Cl-BisGMA instead of BisGMA, the WSP was decreased from 2.95% (F1) to 0.41% (F2) with no significant change in WSL. However, the WSL increased with high Cl-BisGMA content. Biological tests revealed that all the resins were biocompatible during CL1 incubation. SignificanceThe experimental resins based on Cl-BisGMA exhibited improved properties compared with the control samples, e.g., biocompatibility and lower viscosity, indicating that Cl-BisGMA can be considered as a potential monomer for application in dental resin composites.

Analysis of Double Bond Conversion of Photopolymerizable Monomers by FTIR-ATR Spectroscopy

An experiment for the calculation of the degree of double bond conversion, after a polymerization reaction, of photopolymerizable liquid monomers using FTIR-ATR spectroscopy is reported. The experi...

BisGMA analogues as monomers and diluents for dental restorative composite materials

Current commercially available dental composite materials have certain limitations for their use, including high monomer viscosity and high polymerization shrinkage, resulting in residual stresses and interfacial gaps. This study focused on the chemical modification of resin monomer bisphenol A-glycidyl methacrylate (bisGMA), so as to reduce the viscosity and polymerization shrinkage. In this design, the hydroxyl groups of bisGMA were transformed into ester groups with various alkyl chain length and branching. The modified monomers showed promising properties including reduced viscosity, reduced polymerization shrinkage, increased hydrophobicity, increased degree of double bond conversion, and improved mechanical properties of the resulting dental resin composites. The structure/property relationships of the new monomers were investigated, and optimal monomer structures were identified for dental composites with improved properties.

Preparation and characterization of high radio-opaque E-glass fiber-reinforced composite with iodine containing methacrylate monomer

ObjectiveThe purpose of this study was to prepare radio-opaque E-glass fiber-reinforced composite (EFRC) with synthesized iodine containing methacrylate monomer. MethodsThe synthesized iodine containing methacrylate monomer 2-hydroxy-3- methacryloyloxypropyl(2,3,5- triiodobenzoate) (HMTIB) was mixed with Bis-GMA and MMA in different mass ratio to prepare resin impregnating solution (RIS), and RIS without HMTIB was used as control. CQ and DMAEMA were added as photoinitiation system. E-glass fiber was thoroughly wetted by resin impregnating solution to prepare radio-opaque EFRC. Degree of double bond conversion (DC) was investigated by FT-IR analysis. Fiber volume fraction was analyzed by combustion and gravimetric analyzes. The Flexural strength (FS) and modulus (FM) of EFRC were measured using a three-point bending set up. Water sorption (WS) and solubility (SL) were measured until the mass variation of EFRC in distilled water kept stable. Radiographs were taken to determine the radiopacity of EFRC. ResultsThe FT-IR and 1H NMR spectra of HMTIB revealed that it was the same as designed. ANOVA analysis revealed that increasing HMTIB concentration in RIS would decrease DC and increase fiber volume fraction. When compared with control EFRC, all of HMTIB containing EFRCs had higher or comparable FS and FM, no matter before or after water immersion. WS of EFRC decreased with increasing HMTIB concentration, while SL was nearly kept the same. Radiopacity of EFRC increased with increasing HMTIB concentration. SignificanceThe synthesized monomer HMTIB could be used to prepare EFRC with high radiopacity. Moreover, HMTIB containing EFRC would also have high mechanical properties and low WS.

Photo-curable resists for inkjet dispensing applied in large area and high throughput roll-to-roll nanoimprint processes

We report two newly developed photo-curable resists specifically engineered for inkjet dispensing facilitating nanoimprint lithography (NIL) in a high-throughput environment. The viscosity of the novel NIL resists was adjusted especially to enable inkjet dispensing at room temperature. The novel resists can be applied either in NIL batch processes or in high throughput processes like roll-to-roll NIL (R2R-NIL). Batch-wise imprints were performed on various substrates as Si or plastics demonstrating the distinctive application versatility of the novel materials. The very fast curing speed of these materials is discussed in detail with the aid of FT-IR and photo-DSC measurements. The experiments demonstrate a high degree of double bond conversion of about 80% after curing and a fast curing in a few seconds even at a low radiation intensity of 0.2mWcm−2. The novel materials show excellent adhesion on different substrates and high optical transparency. The high throughput capability of the novel materials is demonstrated by R2R-NIL processes performed at a web speed of up to 30mmin−1.

Methacrylate-based polymer blends containing oligomeric 1,2-polybutadienes

Partly miscible polymer blends with semi-IPNs structure built from polydimethacrylate networks and hydroxyl-terminated liquid polybutadienes with predominant 1,2-structure (LBH) were prepared by photopolymerization method. Photopolymerization kinetics of dimethacrylate–LBH mixtures were monitored by DSC technique under isothermal conditions. Kinetic curves and related parameters, like polymerization rate and degree of double bond conversion were determined as functions of dimethacrylate structure, LBH molecular mass, and its content in the mixture as well as polymerization temperature. The photopolymerization kinetics and activation energy for the polymerization rate were discussed taking into account the phase separation occurring during the curing reaction. The extent of phase separation (based on Tg’s measurements) depended on LBH content and dimethacrylate chemical structure. The effect of LBH content on hardness of polymer blends was also examined.