The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform
Toyoharu Hayashi - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of novel UV-curable difunctional thiourethane methacrylate and studies on organic–inorganic nanocomposite hard coatings for high refractive index plastic lenses
Progress in Organic Coatings, 2008Co-Authors: Norio Nakayama, Toyoharu HayashiAbstract:This study relates to the development of ultraviolet (UV)-curable, organic–inorganic nanocomposite hard coatings for plastic lens substrates, especially for polythiourethane (PTU) and polycarbonate (PC). Novel difunctional thiourethane methacrylate (mercaptoethylsulfide-thiourethane methacrylate: coded MES-TUMA and isophorone diisocyanate-mercaptoethylsulfide-thiourethane methacrylate: coded IPDI-MES-TUMA) was synthesized to enhance the adhesive strength for PTU. On the basis of IR, 1H NMR, electron spray ionisation-mass spectrometry (ESI-MS) analysis and gel permeation chromatography (GPC), the expected structures were confirmed. These difunctional thiourethane Methacrylates were easily mixed with multifunctional urethane acrylate, surface-modified ZrO2–TiO2 nanoparticles and photoinitiator in coating formulations. The UV-cured organic–inorganic nanocomposites were very useful as hard coatings for high refractive index plastic lenses such as PTU and PC.
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synthesis of novel uv curable difunctional thiourethane methacrylate and studies on organic inorganic nanocomposite hard coatings for high refractive index plastic lenses
Progress in Organic Coatings, 2008Co-Authors: Norio Nakayama, Toyoharu HayashiAbstract:This study relates to the development of ultraviolet (UV)-curable, organic–inorganic nanocomposite hard coatings for plastic lens substrates, especially for polythiourethane (PTU) and polycarbonate (PC). Novel difunctional thiourethane methacrylate (mercaptoethylsulfide-thiourethane methacrylate: coded MES-TUMA and isophorone diisocyanate-mercaptoethylsulfide-thiourethane methacrylate: coded IPDI-MES-TUMA) was synthesized to enhance the adhesive strength for PTU. On the basis of IR, 1H NMR, electron spray ionisation-mass spectrometry (ESI-MS) analysis and gel permeation chromatography (GPC), the expected structures were confirmed. These difunctional thiourethane Methacrylates were easily mixed with multifunctional urethane acrylate, surface-modified ZrO2–TiO2 nanoparticles and photoinitiator in coating formulations. The UV-cured organic–inorganic nanocomposites were very useful as hard coatings for high refractive index plastic lenses such as PTU and PC.
Ailin Mahdkhah - One of the best experts on this subject based on the ideXlab platform.
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Effect of rinsing time and surface contamination on the bond strength of silorane-based and dimethacrylate-based composites to enamel.
Journal of clinical and experimental dentistry, 2018Co-Authors: Farnoosh Fallahzadeh, Mohammad Atai, Shirin Ghasemi, Ailin MahdkhahAbstract:The aim of this study was to assess whether saliva contamination and rinsing time for 15, 30, and 60 seconds, affects the shear bond strength of silorane and methacrylate-based composites to enamel. Two light cure resin, P60 (3M ESPE) and Filtek LS Silorane were tested. 120 sound premolars were randomly divided into four groups of 30 teeth based on composite type with or without saliva contamination after etching and rinsing. Each group was further divided into three subgroups according to their rinsing time. Then a cylinder of the composite was bonded to the enamel and Shear bond strength was assessed. To determine the failure mode, the bonded surfaces were then observed under SEM. In addition, the DC of each group was measured at pH levels of 4 and 7 using FTIR spectroscopy. The data were analyzed with one-way ANOVA and post hoc analysis followed by Fisher's least significant difference. The bond strength of the non-contaminated methacrylate group was significantly higher than the other groups (p< 0.0001). In addition, there was no significant deference between the methacrylate subgroups. In the silorane groups, the shear bond strength was higher in the rinsing time of 15 seconds. Failure pattern was mainly adhesive. The DC of the Methacrylates had no significant difference at pH 4 and pH 7, but was significantly higher than that of siloranes (p< 0.0001). While the DC of the siloranes at pH 4 was significantly higher than at pH 7 (p< 0.0001). Saliva contamination in both composites reduces bond strength. Increasing rinsing time in Methacrylates proves ineffective. In non-contaminated siloranes, excessive rinsing time reduced bond strength. The best-recommended rinsing time for both composite is 15 seconds. Key words:Composite resins, silorane composite resin, Methacrylates, shear strength.
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Effect of rinsing time and surface contamination on the bond strength of silorane-based and dimethacrylate-based composites to enamel.
Journal of Clinical and Experimental Dentistry, 2018Co-Authors: Farnoosh Fallahzadeh, Mohammad Atai, Shirin Ghasemi, Ailin MahdkhahAbstract:Background The aim of this study was to assess whether saliva contamination and rinsing time for 15, 30, and 60 seconds, affects the shear bond strength of silorane and methacrylate-based composites to enamel. Material and Methods Two light cure resin, P60 (3M ESPE) and Filtek LS Silorane were tested. 120 sound premolars were randomly divided into four groups of 30 teeth based on composite type with or without saliva contamination after etching and rinsing. Each group was further divided into three subgroups according to their rinsing time. Then a cylinder of the composite was bonded to the enamel and Shear bond strength was assessed. To determine the failure mode, the bonded surfaces were then observed under SEM. In addition, the DC of each group was measured at pH levels of 4 and 7 using FTIR spectroscopy. The data were analyzed with one-way ANOVA and post hoc analysis followed by Fisher's least significant difference. Results The bond strength of the non-contaminated methacrylate group was significantly higher than the other groups (p< 0.0001). In addition, there was no significant deference between the methacrylate subgroups. In the silorane groups, the shear bond strength was higher in the rinsing time of 15 seconds. Failure pattern was mainly adhesive. The DC of the Methacrylates had no significant difference at pH 4 and pH 7, but was significantly higher than that of siloranes (p< 0.0001). While the DC of the siloranes at pH 4 was significantly higher than at pH 7 (p< 0.0001). Conclusions Saliva contamination in both composites reduces bond strength. Increasing rinsing time in Methacrylates proves ineffective. In non-contaminated siloranes, excessive rinsing time reduced bond strength. The best-recommended rinsing time for both composite is 15 seconds. Key words:Composite resins, silorane composite resin, Methacrylates, shear strength.
Norio Nakayama - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of novel UV-curable difunctional thiourethane methacrylate and studies on organic–inorganic nanocomposite hard coatings for high refractive index plastic lenses
Progress in Organic Coatings, 2008Co-Authors: Norio Nakayama, Toyoharu HayashiAbstract:This study relates to the development of ultraviolet (UV)-curable, organic–inorganic nanocomposite hard coatings for plastic lens substrates, especially for polythiourethane (PTU) and polycarbonate (PC). Novel difunctional thiourethane methacrylate (mercaptoethylsulfide-thiourethane methacrylate: coded MES-TUMA and isophorone diisocyanate-mercaptoethylsulfide-thiourethane methacrylate: coded IPDI-MES-TUMA) was synthesized to enhance the adhesive strength for PTU. On the basis of IR, 1H NMR, electron spray ionisation-mass spectrometry (ESI-MS) analysis and gel permeation chromatography (GPC), the expected structures were confirmed. These difunctional thiourethane Methacrylates were easily mixed with multifunctional urethane acrylate, surface-modified ZrO2–TiO2 nanoparticles and photoinitiator in coating formulations. The UV-cured organic–inorganic nanocomposites were very useful as hard coatings for high refractive index plastic lenses such as PTU and PC.
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synthesis of novel uv curable difunctional thiourethane methacrylate and studies on organic inorganic nanocomposite hard coatings for high refractive index plastic lenses
Progress in Organic Coatings, 2008Co-Authors: Norio Nakayama, Toyoharu HayashiAbstract:This study relates to the development of ultraviolet (UV)-curable, organic–inorganic nanocomposite hard coatings for plastic lens substrates, especially for polythiourethane (PTU) and polycarbonate (PC). Novel difunctional thiourethane methacrylate (mercaptoethylsulfide-thiourethane methacrylate: coded MES-TUMA and isophorone diisocyanate-mercaptoethylsulfide-thiourethane methacrylate: coded IPDI-MES-TUMA) was synthesized to enhance the adhesive strength for PTU. On the basis of IR, 1H NMR, electron spray ionisation-mass spectrometry (ESI-MS) analysis and gel permeation chromatography (GPC), the expected structures were confirmed. These difunctional thiourethane Methacrylates were easily mixed with multifunctional urethane acrylate, surface-modified ZrO2–TiO2 nanoparticles and photoinitiator in coating formulations. The UV-cured organic–inorganic nanocomposites were very useful as hard coatings for high refractive index plastic lenses such as PTU and PC.
Farnoosh Fallahzadeh - One of the best experts on this subject based on the ideXlab platform.
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Effect of rinsing time and surface contamination on the bond strength of silorane-based and dimethacrylate-based composites to enamel.
Journal of clinical and experimental dentistry, 2018Co-Authors: Farnoosh Fallahzadeh, Mohammad Atai, Shirin Ghasemi, Ailin MahdkhahAbstract:The aim of this study was to assess whether saliva contamination and rinsing time for 15, 30, and 60 seconds, affects the shear bond strength of silorane and methacrylate-based composites to enamel. Two light cure resin, P60 (3M ESPE) and Filtek LS Silorane were tested. 120 sound premolars were randomly divided into four groups of 30 teeth based on composite type with or without saliva contamination after etching and rinsing. Each group was further divided into three subgroups according to their rinsing time. Then a cylinder of the composite was bonded to the enamel and Shear bond strength was assessed. To determine the failure mode, the bonded surfaces were then observed under SEM. In addition, the DC of each group was measured at pH levels of 4 and 7 using FTIR spectroscopy. The data were analyzed with one-way ANOVA and post hoc analysis followed by Fisher's least significant difference. The bond strength of the non-contaminated methacrylate group was significantly higher than the other groups (p< 0.0001). In addition, there was no significant deference between the methacrylate subgroups. In the silorane groups, the shear bond strength was higher in the rinsing time of 15 seconds. Failure pattern was mainly adhesive. The DC of the Methacrylates had no significant difference at pH 4 and pH 7, but was significantly higher than that of siloranes (p< 0.0001). While the DC of the siloranes at pH 4 was significantly higher than at pH 7 (p< 0.0001). Saliva contamination in both composites reduces bond strength. Increasing rinsing time in Methacrylates proves ineffective. In non-contaminated siloranes, excessive rinsing time reduced bond strength. The best-recommended rinsing time for both composite is 15 seconds. Key words:Composite resins, silorane composite resin, Methacrylates, shear strength.
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Effect of rinsing time and surface contamination on the bond strength of silorane-based and dimethacrylate-based composites to enamel.
Journal of Clinical and Experimental Dentistry, 2018Co-Authors: Farnoosh Fallahzadeh, Mohammad Atai, Shirin Ghasemi, Ailin MahdkhahAbstract:Background The aim of this study was to assess whether saliva contamination and rinsing time for 15, 30, and 60 seconds, affects the shear bond strength of silorane and methacrylate-based composites to enamel. Material and Methods Two light cure resin, P60 (3M ESPE) and Filtek LS Silorane were tested. 120 sound premolars were randomly divided into four groups of 30 teeth based on composite type with or without saliva contamination after etching and rinsing. Each group was further divided into three subgroups according to their rinsing time. Then a cylinder of the composite was bonded to the enamel and Shear bond strength was assessed. To determine the failure mode, the bonded surfaces were then observed under SEM. In addition, the DC of each group was measured at pH levels of 4 and 7 using FTIR spectroscopy. The data were analyzed with one-way ANOVA and post hoc analysis followed by Fisher's least significant difference. Results The bond strength of the non-contaminated methacrylate group was significantly higher than the other groups (p< 0.0001). In addition, there was no significant deference between the methacrylate subgroups. In the silorane groups, the shear bond strength was higher in the rinsing time of 15 seconds. Failure pattern was mainly adhesive. The DC of the Methacrylates had no significant difference at pH 4 and pH 7, but was significantly higher than that of siloranes (p< 0.0001). While the DC of the siloranes at pH 4 was significantly higher than at pH 7 (p< 0.0001). Conclusions Saliva contamination in both composites reduces bond strength. Increasing rinsing time in Methacrylates proves ineffective. In non-contaminated siloranes, excessive rinsing time reduced bond strength. The best-recommended rinsing time for both composite is 15 seconds. Key words:Composite resins, silorane composite resin, Methacrylates, shear strength.
David M Haddleton - One of the best experts on this subject based on the ideXlab platform.
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cu 0 rdrp of Methacrylates in dmso importance of the initiator
Polymer Chemistry, 2018Co-Authors: Glen R Jones, Richard Whitfield, Athina Anastasaki, Nuttapol Risangud, Alexandre Simula, Daniel J Keddie, David M HaddletonAbstract:The controlled radical polymerization of Methacrylates via Cu(0)-mediated RDRP is challenging in comparison to acrylates with most reports illustrating higher dispersities, lower monomer conversions and poorer end group fidelity relative to the acrylic analogues. Herein, we present the successful synthesis of poly(methyl methacrylate) (PMMA) in DMSO by judicious selection of optimal reaction conditions. The effect of the initiator, ligand and temperature on the rate and control of the polymerization is investigated and discussed. Under carefully optimized conditions enhanced control over the molecular weight distributions is obtained furnishing methacrylic polymers with dispersities as low as 1.10, even at very high conversions. A range of Methacrylates were found to be tolerant to the optimized polymerization conditions including hydrophobic, hydrophilic and functional Methacrylates including methyl and benzyl methacrylate, ethylene glycol methyl ether methacrylate and glycidyl methacrylate. The control retained during the polymerization is further highlighted by in situ chain extensions yielding well-defined block polyMethacrylates.
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copper mediated living radical polymerisation interactions between monomer and catalyst
Dalton Transactions, 2003Co-Authors: Jeetan Lad, Simon Harrisson, Giuseppe Mantovani, David M HaddletonAbstract:The mechanism of copper(I) mediated living radical polymerisation (ATRP) of vinyl monomers has been widely assumed to be relatively simple. However, monomer reactivity ratios in ATRP can be significantly different from those in conventional radical polymerisation, and the exact nature of the catalyst is not well understood due to rapid exchange of ligand and monomer at the copper centre under the polymerisation conditions. This paper illustrates aspects of this catalyst system, which complicate the accepted mechanism of this new and important reaction. Coordination of aminoethyl Methacrylates and methoxy[poly(ethylene glycol)] methacrylate monomers is demonstrated by NMR with rMMA = 0.96(2), 0.98(1) and 0.97(1) for dimethylaminoethyl methacrylate (DMAEMA), (diethylamino)ethyl methacrylate (DEAEMA) and (tert-butylamino)ethyl methacrylate (TBAEMA) under free radical polymerisation and 0.74(3), 0.79(3) and 0.69(3) for transition-metal mediated polymerisation.
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Living Radical Polymerization Immobilized on Wang Resins: Synthesis and Harvest of Narrow Polydispersity Poly(methacrylate)s
Macromolecules, 2001Co-Authors: Stéphanie Angot, Neil Ayres, David M HaddletonAbstract:Wang resin has been transformed into an initiator for copper(I)-mediated living radical polymerization of Methacrylates at initiator loading of 0.9 and 3.5 mmol g-1. The immobilized initiator was characterized by ATR FTIR, gel phase 13C NMR, and solid-state CP/MAS 13C NMR using two different spinning frequencies as well as a TOSS pulse sequence. The immobilized initiator has been used to prepare poly(methyl methacrylate), PMMA, homopolymer, and poly(methyl methacrylate)-block-poly(benzyl methacrylate-co-methyl methacrylate), P(MMA)-block-P(BzMA-co-MMA), block copolymers. The poly(methacrylate)s have been harvested from the insoluble resin by a simple trifluoroacetic acid, TFA, wash which selectively cleaved the activated benzyl ester linkage, so as to facilitate analysis. At an initiator loading of 0.9 mmol g-1 the Mn increases linearly with conversion with kinetics following first-order behavior in monomer as would be expected for living polymerization. After 3 h a 61.9% conversion of MMA is reached, wit...
