The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Hongwei Wang - One of the best experts on this subject based on the ideXlab platform.
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improving permeability and chromatographic performance of poly pentaerythritol diacrylate monostearate monolithic column via photo induced thiol acrylate polymerization
Journal of Chromatography A, 2016Co-Authors: Hongwei Wang, Jingyao Bai, Zhongshan Liu, Yating Yao, Lianfang ChenAbstract:A simple approach was developed for rapid preparation of polymeric monolithic columns in UV-transparent fused-silica capillaries via photoinitiated thiol-acrylate polymerization of pentaerythritol diacrylate monostearate (PEDAS) and trimethylolpropane tris(3-mercaptopropionate) (TPTM) within 10min, in which the acrylate homopolymerized and copolymerized with the thiol simultaneously. The morphology, permeability and chromatographic performance of the resulting poly(PEDAS-co-TPTM) Monoliths were studied. It could be observed from SEM that the morphology of poly(PEDAS-co-TPTM) monolith was rather different from that of poly(PEDAS) monolith, which was fabricated via photo-induced free radical polymerization using PEDAS as the sole monomer. Compared with poly(PEDAS) monolith, poly(PEDAS-co-TPTM) monolith possessed better permeability when they were fabricated under the same preparation conditions. By adjusting the composition of porogenic solvents, poly(PEDAS-co-TPTM) monolith exhibited lower plate heights (15.7-17.7μm) than poly(PEDAS) monolith (19.1-37.9μm) in μLC. In addition, 66 unique peptides were positively identified on poly(PEDAS-co-TPTM) monolith when tryptic digest of four proteins was separated by μLC-MS/MS, demonstrating its potential in proteome analysis.
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facile construction of macroporous hybrid Monoliths via thiol methacrylate michael addition click reaction for capillary liquid chromatography
Journal of Chromatography A, 2015Co-Authors: Junjie Ou, Hongwei Wang, Jing DongAbstract:Abstract A facile approach based on thiol-methacrylate Michael addition click reaction was developed for construction of porous hybrid monolithic materials. Three hybrid Monoliths were prepared via thiol-methacrylate click polymerization by using methacrylate-polyhedral oligomeric silsesquioxane (POSS) (cage mixture, n = 8, 10, 12, POSS-MA) and three multi-thiol crosslinkers, 1,6-hexanedithiol (HDT), trimethylolpropane tris(3-mercaptopropionate) (TPTM) and pentaerythritol tetrakis(3-mercaptopropionate) (PTM), respectively, in the presence of porogenic solvents ( n -propanol and PEG 200) and a catalyst (dimethylphenylphosphine, DMPP). The obtained Monoliths possessed high thermal and chemical stabilities. Besides, they all exhibited high column efficiencies and excellent separation abilities in capillary liquid chromatography (cLC). The highest column efficiency could reach ca. 195,000 N/m for butylbenzene on the monolith prepared with POSS-MA and TPTM (monolith POSS-TPTM) in reversed-phase (RP) mode at 0.64 mm/s. Good chromatographic performance were all achieved in the separations of polycyclic aromatic hydrocarbons (PAHs), phenols, anilines, EPA 610 as well as bovine serum albumin (BSA) digest. The high column efficiencies in the range of 51,400–117,000 N/m (achieved on the monolith POSS-PTM in RP mode) convincingly demonstrated the high separation abilities of these thiol-methacrylate based hybrid Monoliths. All the results demonstrated the feasibility of the phosphines catalyzed thiol-methacrylate Michael addition click reaction in fabrication of monolithic columns with high efficiency for cLC applications.
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chromatographic assessment of two hybrid Monoliths prepared via epoxy amine ring opening polymerization and methacrylate based free radical polymerization using methacrylate epoxy cyclosiloxane as functional monomer
Journal of Chromatography A, 2014Co-Authors: Junjie Ou, Guang Huang, Hongwei Wang, Jing DongAbstract:Abstract Two kinds of hybrid monolithic columns were prepared by using methacrylate epoxy cyclosiloxane (epoxy-MA) as functional monomer, containing three epoxy moieties and one methacrylate group. One column was in situ fabricated by ring-opening polymerization of epoxy-MA and 1,10-diaminodecane (DAD) using a porogenic system consisting of isopropanol (IPA), H2O and ethanol at 65 °C for 12 h. The other was prepared by free radical polymerization of epoxy-MA and ethylene dimethacrylate (EDMA) using 1-propanol and 1,4-butanediol as the porogenic solvents at 60 °C for 12 h. Two hybrid Monoliths were investigated on the morphology and chromatographic assessment. Although two kinds of monolithic columns were prepared with epoxy-MA, their morphologies looked rather different. It could be found that the epoxy-MA–DAD monolith possessed higher column efficiencies (25,000–34,000 plates/m) for the separation of alkylbenzenes than the epoxy-MA–EDMA monolith (12,000–13,000 plates/m) in reversed-phase nano-liquid chromatography (nano-LC). Depending on the remaining epoxy or methacrylate groups on the surface of two pristine Monoliths, the epoxy-MA–EDMA monolith could be easily modified with 1-octadecylamine (ODA) via ring-opening reaction, while the epoxy-MA–DAD monolith could be modified with stearyl methacrylate (SMA) via free radical reaction. The chromatographic performance for the separation of alkylbenzenes on SMA-modified epoxy-MA–DAD monolith was remarkably improved (42,000-54,000 plates/m) when compared with that on pristine epoxy-MA–DAD monolith, while it was not obviously enhanced on ODA-modified epoxy-MA–EDMA monolith when compared with that on pristine epoxy-MA–EDMA monolith. The enhancement of the column efficiency of epoxy-MA–DAD monolith after modification might be ascribed to the decreased mass-transfer resistence. The two kinds of hybrid Monoliths were also applied for separations of six phenols and seven basic compounds in nano-LC.
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chromatographic assessment of two hybrid Monoliths prepared via epoxy amine ring opening polymerization and methacrylate based free radical polymerization using methacrylate epoxy cyclosiloxane as functional monomer
Journal of Chromatography A, 2014Co-Authors: Junjie Ou, Guang Huang, Hongwei Wang, Jing DongAbstract:Two kinds of hybrid monolithic columns were prepared by using methacrylate epoxy cyclosiloxane (epoxy-MA) as functional monomer, containing three epoxy moieties and one methacrylate group. One column was in situ fabricated by ring-opening polymerization of epoxy-MA and 1,10-diaminodecane (DAD) using a porogenic system consisting of isopropanol (IPA), H2O and ethanol at 65 degrees C for 12h. The other was prepared by free radical polymerization of epoxy-MA and ethylene dimethacrylate (EDMA) using 1-propanol and 1,4-butanediol as the porogenic solvents at 60 degrees C for 12h. Two hybrid Monoliths were investigated on the morphology and chromatographic assessment. Although two kinds of monolithic columns were prepared with epoxy-MA, their morphologies looked rather different. It could be found that the epoxy-MA-DAD monolith possessed higher column efficiencies (25,000-34,000 plates/m) for the separation of alkylbenzenes than the epoxy-MA-EDMA monolith (12,000-13,000 plates/m) in reversed-phase nano-liquid chromatography (nano-LC). Depending on the remaining epoxy or methacrylate groups on the surface of two pristine Monoliths, the epoxy-MA-EDMA monolith could be easily modified with 1-octadecylamine (ODA) via ring-opening reaction, while the epoxy-MA-DAD monolith could be modified with stearyl methacrylate (SMA) via free radical reaction. The chromatographic performance for the separation of alkylbenzenes on SMA-modified epoxy-MA-DAD monolith was remarkably improved (42,000-54,000 plates/m) when compared with that on pristine epoxy-MA-DAD monolith, while it was not obviously enhanced on ODA-modified epoxy-MA-EDMA monolith when compared with that on pristine epoxy-MA-EDMA monolith. The enhancement of the column efficiency of epoxy-MA-DAD monolith after modification might be ascribed to the decreased mass-transfer resistence. The two kinds of hybrid Monoliths were also applied for separations of six phenols and seven basic compounds in nano-LC. (C) 2014 Elsevier B.V. All rights reserved.
Jing Dong - One of the best experts on this subject based on the ideXlab platform.
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facile construction of macroporous hybrid Monoliths via thiol methacrylate michael addition click reaction for capillary liquid chromatography
Journal of Chromatography A, 2015Co-Authors: Junjie Ou, Hongwei Wang, Jing DongAbstract:Abstract A facile approach based on thiol-methacrylate Michael addition click reaction was developed for construction of porous hybrid monolithic materials. Three hybrid Monoliths were prepared via thiol-methacrylate click polymerization by using methacrylate-polyhedral oligomeric silsesquioxane (POSS) (cage mixture, n = 8, 10, 12, POSS-MA) and three multi-thiol crosslinkers, 1,6-hexanedithiol (HDT), trimethylolpropane tris(3-mercaptopropionate) (TPTM) and pentaerythritol tetrakis(3-mercaptopropionate) (PTM), respectively, in the presence of porogenic solvents ( n -propanol and PEG 200) and a catalyst (dimethylphenylphosphine, DMPP). The obtained Monoliths possessed high thermal and chemical stabilities. Besides, they all exhibited high column efficiencies and excellent separation abilities in capillary liquid chromatography (cLC). The highest column efficiency could reach ca. 195,000 N/m for butylbenzene on the monolith prepared with POSS-MA and TPTM (monolith POSS-TPTM) in reversed-phase (RP) mode at 0.64 mm/s. Good chromatographic performance were all achieved in the separations of polycyclic aromatic hydrocarbons (PAHs), phenols, anilines, EPA 610 as well as bovine serum albumin (BSA) digest. The high column efficiencies in the range of 51,400–117,000 N/m (achieved on the monolith POSS-PTM in RP mode) convincingly demonstrated the high separation abilities of these thiol-methacrylate based hybrid Monoliths. All the results demonstrated the feasibility of the phosphines catalyzed thiol-methacrylate Michael addition click reaction in fabrication of monolithic columns with high efficiency for cLC applications.
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chromatographic assessment of two hybrid Monoliths prepared via epoxy amine ring opening polymerization and methacrylate based free radical polymerization using methacrylate epoxy cyclosiloxane as functional monomer
Journal of Chromatography A, 2014Co-Authors: Junjie Ou, Guang Huang, Hongwei Wang, Jing DongAbstract:Abstract Two kinds of hybrid monolithic columns were prepared by using methacrylate epoxy cyclosiloxane (epoxy-MA) as functional monomer, containing three epoxy moieties and one methacrylate group. One column was in situ fabricated by ring-opening polymerization of epoxy-MA and 1,10-diaminodecane (DAD) using a porogenic system consisting of isopropanol (IPA), H2O and ethanol at 65 °C for 12 h. The other was prepared by free radical polymerization of epoxy-MA and ethylene dimethacrylate (EDMA) using 1-propanol and 1,4-butanediol as the porogenic solvents at 60 °C for 12 h. Two hybrid Monoliths were investigated on the morphology and chromatographic assessment. Although two kinds of monolithic columns were prepared with epoxy-MA, their morphologies looked rather different. It could be found that the epoxy-MA–DAD monolith possessed higher column efficiencies (25,000–34,000 plates/m) for the separation of alkylbenzenes than the epoxy-MA–EDMA monolith (12,000–13,000 plates/m) in reversed-phase nano-liquid chromatography (nano-LC). Depending on the remaining epoxy or methacrylate groups on the surface of two pristine Monoliths, the epoxy-MA–EDMA monolith could be easily modified with 1-octadecylamine (ODA) via ring-opening reaction, while the epoxy-MA–DAD monolith could be modified with stearyl methacrylate (SMA) via free radical reaction. The chromatographic performance for the separation of alkylbenzenes on SMA-modified epoxy-MA–DAD monolith was remarkably improved (42,000-54,000 plates/m) when compared with that on pristine epoxy-MA–DAD monolith, while it was not obviously enhanced on ODA-modified epoxy-MA–EDMA monolith when compared with that on pristine epoxy-MA–EDMA monolith. The enhancement of the column efficiency of epoxy-MA–DAD monolith after modification might be ascribed to the decreased mass-transfer resistence. The two kinds of hybrid Monoliths were also applied for separations of six phenols and seven basic compounds in nano-LC.
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chromatographic assessment of two hybrid Monoliths prepared via epoxy amine ring opening polymerization and methacrylate based free radical polymerization using methacrylate epoxy cyclosiloxane as functional monomer
Journal of Chromatography A, 2014Co-Authors: Junjie Ou, Guang Huang, Hongwei Wang, Jing DongAbstract:Two kinds of hybrid monolithic columns were prepared by using methacrylate epoxy cyclosiloxane (epoxy-MA) as functional monomer, containing three epoxy moieties and one methacrylate group. One column was in situ fabricated by ring-opening polymerization of epoxy-MA and 1,10-diaminodecane (DAD) using a porogenic system consisting of isopropanol (IPA), H2O and ethanol at 65 degrees C for 12h. The other was prepared by free radical polymerization of epoxy-MA and ethylene dimethacrylate (EDMA) using 1-propanol and 1,4-butanediol as the porogenic solvents at 60 degrees C for 12h. Two hybrid Monoliths were investigated on the morphology and chromatographic assessment. Although two kinds of monolithic columns were prepared with epoxy-MA, their morphologies looked rather different. It could be found that the epoxy-MA-DAD monolith possessed higher column efficiencies (25,000-34,000 plates/m) for the separation of alkylbenzenes than the epoxy-MA-EDMA monolith (12,000-13,000 plates/m) in reversed-phase nano-liquid chromatography (nano-LC). Depending on the remaining epoxy or methacrylate groups on the surface of two pristine Monoliths, the epoxy-MA-EDMA monolith could be easily modified with 1-octadecylamine (ODA) via ring-opening reaction, while the epoxy-MA-DAD monolith could be modified with stearyl methacrylate (SMA) via free radical reaction. The chromatographic performance for the separation of alkylbenzenes on SMA-modified epoxy-MA-DAD monolith was remarkably improved (42,000-54,000 plates/m) when compared with that on pristine epoxy-MA-DAD monolith, while it was not obviously enhanced on ODA-modified epoxy-MA-EDMA monolith when compared with that on pristine epoxy-MA-EDMA monolith. The enhancement of the column efficiency of epoxy-MA-DAD monolith after modification might be ascribed to the decreased mass-transfer resistence. The two kinds of hybrid Monoliths were also applied for separations of six phenols and seven basic compounds in nano-LC. (C) 2014 Elsevier B.V. All rights reserved.
Hiroshi Uyama - One of the best experts on this subject based on the ideXlab platform.
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phase separation approach to a reactive polycarbonate monolith for click modifications
Polymer, 2015Co-Authors: Junji Sakamoto, Andre J Van Der Vlies, Urara Hasegawa, Hiroshi UyamaAbstract:Abstract A new polycarbonate monolith carrying allyl groups has been introduced. The monolith was fabricated via the phase separation induced by adding cyclohexane to a solution of the polymer in chloroform. Cross-sectional analysis of the monolith was performed by scanning electron microscopy that unveiled a three-dimensionally networked porous structure inside the monolith. As a result of nitrogen adsorption/desorption experiments, the specific surface area of the monolith was calculated to be 145 m 2 /g with the Brunauer Emmett Teller equation. The allyl groups of the monolith were subjected to a thiol-ene click reaction with 2-mercaptoethanol and an olefin metathesis with a Grubbs catalyst. With the porous structure largely maintained, the click reaction attained high conversions and the metathesis internally crosslinked the monolith to the degree that confers solvent resistance. These results qualify the present monolith as a versatile platform for chemical transformations into a wide range of functional Monoliths.
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facile fabrication of poly methyl methacrylate monolith via thermally induced phase separation by utilizing unique cosolvency
Polymer, 2014Co-Authors: Shinya Yoneda, Urara Hasegawa, Hiroshi UyamaAbstract:Abstract Poly(methyl methacrylate) (PMMA) Monoliths with a three-dimensional continuous interconnected porous structure in a single piece were fabricated via thermally induced phase separation (TIPS) by utilizing unique cosolvency toward PMMA. We found that PMMA was soluble in a mixture of non-solvents (ethanol and water) at 60 °C. Cooling the solution resulted in formation of a monolith having interconnected pores. Cross-sectional analysis using scanning electron microscopy (SEM) showed a continuous porous network with submicron-sized skeleton. The pore size of the monolith was readily controlled by varying the fabrication parameters such as the polymer concentration and molecular weight, the cooling temperature and the solvent composition. The cross-section of the monolith showed high water repellency. The PMMA monolith was also obtained in a mixture of isopropanol and water with an appropriate solvent ratio.
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porous acrylate monolith supported pd nanoparticles highly active and reusable catalyst for suzuki miyaura reaction in water
RSC Advances, 2014Co-Authors: Mahasweta Nandi, Hiroshi UyamaAbstract:The present work describes the use of palladium-Schiff-base functionalized methyl methacrylate-glycidyl methacrylate (MMA-GMA) copolymer Monoliths for the SMC reaction of aryl halides in water under aerobic conditions. Highly porous MMA-GMA copolymer Monoliths with interconnected network morphology have been fabricated by a thermally induced phase separation technique (TIPS). The copolymer synthesized here via radical polymerization has a molecular weight of 162000 and GMA content of 11 mol%. The Monoliths have been functionalized by aminolysis of the epoxy groups by ethylene diamine, followed by their condensation with salicylaldehyde to form the Schiff base. The donor atoms of the Schiff base bind Pd(II) ions very efficiently to generate an ortho-metallated Pd(II)–Schiff base complex anchored on acrylate copolymer Monoliths (Pd-SBAM). The material has been found to exhibit excellent catalytic activity, high stability and turn over frequency (TOF) for SMC reactions. The biphenyl products have been obtained with very high yield and the catalyst could be reused for several reaction cycles without significant loss of its activity. Moreover, the heterogeneous catalyst has been developed in the form of a monolith, which facilitates its easy separation from the reaction medium.
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facile fabrication of polycarbonate monolith by non solvent induced phase separation method
Polymer, 2012Co-Authors: Takashi Fujimoto, Hiroshi UyamaAbstract:Abstract Polycarbonate (PC) Monoliths with three-dimensional continuous interconnected porous structure in a single piece are fabricated via non-solvent induced phase separation (NIPS) for the first time. The morphology of fabricated monolith is observed through SEM, the surface area is determined by BET method and the thermal property is measured via DSC. The pore and skeleton sizes of the monolith are readily controlled by varying the fabrication parameters such as the polymer concentration and molecular weight, the standing temperature and the solvent composition. The PC monolith possesses relatively large surface area and sharp melting point at 232 °C. These Monoliths with high thermal stability can offer various potential applications of functional materials.
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fabrication of mesoporous polymer monolith a template free approach
Chemical Communications, 2011Co-Authors: Keisuke Okada, Mahasweta Nandi, Takashi Tsujimoto, Jun Maruyama, Katsuyoshi Kondoh, Hiroshi UyamaAbstract:Mesoporous polyacrylonitrile (PAN) monolith has been fabricated by a template-free approach using the unique affinity of PAN towards a water/dimethyl sulfoxide (DMSO) mixture. A newly developed Thermally Induced Phase Separation Technique (TIPS) has been used to obtain the polymer Monoliths and their microstructures have been controlled by optimizing the concentration and cooling temperature.
Junjie Ou - One of the best experts on this subject based on the ideXlab platform.
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facile construction of macroporous hybrid Monoliths via thiol methacrylate michael addition click reaction for capillary liquid chromatography
Journal of Chromatography A, 2015Co-Authors: Junjie Ou, Hongwei Wang, Jing DongAbstract:Abstract A facile approach based on thiol-methacrylate Michael addition click reaction was developed for construction of porous hybrid monolithic materials. Three hybrid Monoliths were prepared via thiol-methacrylate click polymerization by using methacrylate-polyhedral oligomeric silsesquioxane (POSS) (cage mixture, n = 8, 10, 12, POSS-MA) and three multi-thiol crosslinkers, 1,6-hexanedithiol (HDT), trimethylolpropane tris(3-mercaptopropionate) (TPTM) and pentaerythritol tetrakis(3-mercaptopropionate) (PTM), respectively, in the presence of porogenic solvents ( n -propanol and PEG 200) and a catalyst (dimethylphenylphosphine, DMPP). The obtained Monoliths possessed high thermal and chemical stabilities. Besides, they all exhibited high column efficiencies and excellent separation abilities in capillary liquid chromatography (cLC). The highest column efficiency could reach ca. 195,000 N/m for butylbenzene on the monolith prepared with POSS-MA and TPTM (monolith POSS-TPTM) in reversed-phase (RP) mode at 0.64 mm/s. Good chromatographic performance were all achieved in the separations of polycyclic aromatic hydrocarbons (PAHs), phenols, anilines, EPA 610 as well as bovine serum albumin (BSA) digest. The high column efficiencies in the range of 51,400–117,000 N/m (achieved on the monolith POSS-PTM in RP mode) convincingly demonstrated the high separation abilities of these thiol-methacrylate based hybrid Monoliths. All the results demonstrated the feasibility of the phosphines catalyzed thiol-methacrylate Michael addition click reaction in fabrication of monolithic columns with high efficiency for cLC applications.
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chromatographic assessment of two hybrid Monoliths prepared via epoxy amine ring opening polymerization and methacrylate based free radical polymerization using methacrylate epoxy cyclosiloxane as functional monomer
Journal of Chromatography A, 2014Co-Authors: Junjie Ou, Guang Huang, Hongwei Wang, Jing DongAbstract:Abstract Two kinds of hybrid monolithic columns were prepared by using methacrylate epoxy cyclosiloxane (epoxy-MA) as functional monomer, containing three epoxy moieties and one methacrylate group. One column was in situ fabricated by ring-opening polymerization of epoxy-MA and 1,10-diaminodecane (DAD) using a porogenic system consisting of isopropanol (IPA), H2O and ethanol at 65 °C for 12 h. The other was prepared by free radical polymerization of epoxy-MA and ethylene dimethacrylate (EDMA) using 1-propanol and 1,4-butanediol as the porogenic solvents at 60 °C for 12 h. Two hybrid Monoliths were investigated on the morphology and chromatographic assessment. Although two kinds of monolithic columns were prepared with epoxy-MA, their morphologies looked rather different. It could be found that the epoxy-MA–DAD monolith possessed higher column efficiencies (25,000–34,000 plates/m) for the separation of alkylbenzenes than the epoxy-MA–EDMA monolith (12,000–13,000 plates/m) in reversed-phase nano-liquid chromatography (nano-LC). Depending on the remaining epoxy or methacrylate groups on the surface of two pristine Monoliths, the epoxy-MA–EDMA monolith could be easily modified with 1-octadecylamine (ODA) via ring-opening reaction, while the epoxy-MA–DAD monolith could be modified with stearyl methacrylate (SMA) via free radical reaction. The chromatographic performance for the separation of alkylbenzenes on SMA-modified epoxy-MA–DAD monolith was remarkably improved (42,000-54,000 plates/m) when compared with that on pristine epoxy-MA–DAD monolith, while it was not obviously enhanced on ODA-modified epoxy-MA–EDMA monolith when compared with that on pristine epoxy-MA–EDMA monolith. The enhancement of the column efficiency of epoxy-MA–DAD monolith after modification might be ascribed to the decreased mass-transfer resistence. The two kinds of hybrid Monoliths were also applied for separations of six phenols and seven basic compounds in nano-LC.
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chromatographic assessment of two hybrid Monoliths prepared via epoxy amine ring opening polymerization and methacrylate based free radical polymerization using methacrylate epoxy cyclosiloxane as functional monomer
Journal of Chromatography A, 2014Co-Authors: Junjie Ou, Guang Huang, Hongwei Wang, Jing DongAbstract:Two kinds of hybrid monolithic columns were prepared by using methacrylate epoxy cyclosiloxane (epoxy-MA) as functional monomer, containing three epoxy moieties and one methacrylate group. One column was in situ fabricated by ring-opening polymerization of epoxy-MA and 1,10-diaminodecane (DAD) using a porogenic system consisting of isopropanol (IPA), H2O and ethanol at 65 degrees C for 12h. The other was prepared by free radical polymerization of epoxy-MA and ethylene dimethacrylate (EDMA) using 1-propanol and 1,4-butanediol as the porogenic solvents at 60 degrees C for 12h. Two hybrid Monoliths were investigated on the morphology and chromatographic assessment. Although two kinds of monolithic columns were prepared with epoxy-MA, their morphologies looked rather different. It could be found that the epoxy-MA-DAD monolith possessed higher column efficiencies (25,000-34,000 plates/m) for the separation of alkylbenzenes than the epoxy-MA-EDMA monolith (12,000-13,000 plates/m) in reversed-phase nano-liquid chromatography (nano-LC). Depending on the remaining epoxy or methacrylate groups on the surface of two pristine Monoliths, the epoxy-MA-EDMA monolith could be easily modified with 1-octadecylamine (ODA) via ring-opening reaction, while the epoxy-MA-DAD monolith could be modified with stearyl methacrylate (SMA) via free radical reaction. The chromatographic performance for the separation of alkylbenzenes on SMA-modified epoxy-MA-DAD monolith was remarkably improved (42,000-54,000 plates/m) when compared with that on pristine epoxy-MA-DAD monolith, while it was not obviously enhanced on ODA-modified epoxy-MA-EDMA monolith when compared with that on pristine epoxy-MA-EDMA monolith. The enhancement of the column efficiency of epoxy-MA-DAD monolith after modification might be ascribed to the decreased mass-transfer resistence. The two kinds of hybrid Monoliths were also applied for separations of six phenols and seven basic compounds in nano-LC. (C) 2014 Elsevier B.V. All rights reserved.
Dennis H Tolley - One of the best experts on this subject based on the ideXlab platform.
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Monoliths from poly ethylene glycol diacrylate and dimethacrylate for capillary hydrophobic interaction chromatography of proteins
Journal of Chromatography A, 2010Co-Authors: Yuanyuan Li, Dennis H TolleyAbstract:Rigid Monoliths were synthesized solely from poly(ethylene glycol) diacrylates (PEGDA) or poly(ethylene glycol) dimethacrylates (PEGDMA) containing different ethylene glycol chain lengths by one-step UV-initiated polymerization. Methanol/ethyl ether and cyclohexanol/decanol were used as bi-porogen mixtures for the PEGDA and PEGDMA Monoliths, respectively. Effects of PEG chain length, bi-porogen ratio and reaction temperature on monolith morphology and back pressure were investigated. For tri- and tetra-ethylene glycol diacrylates (i.e., PEGDA 258 and PEGDA 302), most combinations of methanol and ethyl ether were effective in forming Monoliths, while for diacrylates containing longer chain lengths (i.e., PEGDA 575 and PEGDA 700), polymerization became more sensitive to the bi-porogen ratio. A similar tendency was also observed for PEGDMA monomers. Polymerization of Monoliths was conducted at approximately 0 °C and room temperature, which produced significant differences in monolith morphology and permeability. Monoliths prepared from PEGDA 258 were found to provide the best chromatographic performance with respect to peak capacity and resolution in hydrophobic interaction chromatography (HIC). Detailed study of these Monoliths demonstrated that chromatographic performance was not affected by changing the ratios of the two porogens, but resulted in almost identical retention times and comparable peak capacities. An optimized PEGDA 258 monolithic column was able to separate proteins using a 20-min elution gradient with a peak capacity of 62. Mass recoveries for test proteins were found to be greater than 90, indicating its excellent biocompatibility. All Monoliths demonstrated nearly no swelling or shrinking in different polarity solvents, and most of them could be stored dry, indicating excellent stability due to their highly crosslinked networks. The preparation of these in situ polymerized single-monomer monolithic columns was highly reproducible. The relative standard deviation (RSD) values based on retention times of retained proteins were all within 2.2%, and in most cases, less than 1.2%. The RSD values based on peak areas were within 9.5%, and in most cases, less than 7.0%. The single-monomer synthesis approach clearly improves column-to-column reproducibility.
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Monoliths from poly ethylene glycol diacrylate and dimethacrylate for capillary hydrophobic interaction chromatography of proteins
Journal of Chromatography A, 2010Co-Authors: Dennis H Tolley, Milton L LeeAbstract:Rigid Monoliths were synthesized solely from poly(ethylene glycol) diacrylates (PEGDA) or poly(ethylene glycol) dimethacrylates (PEGDMA) containing different ethylene glycol chain lengths by one-step UV-initiated polymerization. Methanol/ethyl ether and cyclohexanol/decanol were used as bi-porogen mixtures for the PEGDA and PEGDMA Monoliths, respectively. Effects of PEG chain length, bi-porogen ratio and reaction temperature on monolith morphology and back pressure were investigated. For tri- and tetra-ethylene glycol diacrylates (i.e., PEGDA 258 and PEGDA 302), most combinations of methanol and ethyl ether were effective in forming Monoliths, while for diacrylates containing longer chain lengths (i.e., PEGDA 575 and PEGDA 700), polymerization became more sensitive to the bi-porogen ratio. A similar tendency was also observed for PEGDMA monomers. Polymerization of Monoliths was conducted at approximately 0 degrees C and room temperature, which produced significant differences in monolith morphology and permeability. Monoliths prepared from PEGDA 258 were found to provide the best chromatographic performance with respect to peak capacity and resolution in hydrophobic interaction chromatography (HIC). Detailed study of these Monoliths demonstrated that chromatographic performance was not affected by changing the ratios of the two porogens, but resulted in almost identical retention times and comparable peak capacities. An optimized PEGDA 258 monolithic column was able to separate proteins using a 20-min elution gradient with a peak capacity of 62. Mass recoveries for test proteins were found to be greater than 90, indicating its excellent biocompatibility. All Monoliths demonstrated nearly no swelling or shrinking in different polarity solvents, and most of them could be stored dry, indicating excellent stability due to their highly crosslinked networks. The preparation of these in situ polymerized single-monomer monolithic columns was highly reproducible. The relative standard deviation (RSD) values based on retention times of retained proteins were all within 2.2%, and in most cases, less than 1.2%. The RSD values based on peak areas were within 9.5%, and in most cases, less than 7.0%. The single-monomer synthesis approach clearly improves column-to-column reproducibility.
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polymeric cation exchange monolithic columns containing phosphoric acid functional groups for capillary liquid chromatography of peptides and proteins
Journal of Chromatography A, 2010Co-Authors: Xin Chen, Dennis H Tolley, Milton L LeeAbstract:Two different Monoliths, both containing phosphoric acid functional groups and polyethylene glycol (PEG) functionalities were synthesized for cation-exchange chromatography of peptides and proteins. Phosphoric acid 2-hydroxyethyl methacrylate (PAHEMA) and bis[2-(methacryloyloxy)ethyl] phosphate (BMEP) were reacted with polyethylene glycol diacrylate (PEGDA) and polyethylene glycol acrylate (PEGA), respectively, in 75-mum i.d. UV-transparent fused-silica capillaries by photo-initiated polymerization. The hydrophobicities of the Monoliths were evaluated using propyl paraben under reversed-phase conditions and synthetic peptides under ion-exchange conditions. The resulting Monoliths exhibited lower hydrophobicities than strong cation-exchange Monoliths previously reported using PEGDA as cross-linker. Dynamic binding capacities of 31.2 and 269mg/mL were measured for the PAHEMA-PEGDA and BMEP-PEGA Monoliths, respectively. Synthetic peptides were eluted from both Monoliths in 15min without addition of acetonitrile to the mobile phase. Peak capacities of 50 and 31 were measured for peptides and proteins, respectively, using a PAHEMA-PEGDA monolith. The BMEP-PEGA monolith showed negligible hydrophobicity. A peak capacity of 31 was measured for the BMEP-PEGA monolith when a 20-min salt gradient rate was used to separate proteins. The effects of functional group concentration, mobile phase pH, salt gradient rate, and hydrophobicity on the retention of analytes were investigated. Good run-to-run [relative standard deviation (RSD)<1.99%] and column-to-column (RSD<5.64) reproducibilities were achieved. The performance of the Monoliths in ion-exchange separation of peptides and proteins was superior to other polymeric monolithic columns reported previously when organic solvents were not added to the mobile phase.
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preparation of polymeric Monoliths by copolymerization of acrylate monomers with amine functionalities for anion exchange capillary liquid chromatography of proteins
Journal of Chromatography A, 2009Co-Authors: Yun Li, Binghe Gu, Dennis H TolleyAbstract:Abstract Two novel polymeric Monoliths for anion-exchange capillary liquid chromatography of proteins were prepared in a single step by a simple photoinitiated copolymerization of 2-(diethylamino)ethyl methacrylate and polyethylene glycol diacrylate (PEGDA), or copolymerization of 2-(acryloyloxy)ethyl trimethylammonium chloride and PEGDA, in the presence of selected porogens. The resulting Monoliths contained functionalities of diethylaminoethyl (DEAE) as a weak anion-exchanger and quaternary amine as a strong anion-exchanger, respectively. An alternative weak anion-exchange monolith with DEAE functionalities was also synthesized by chemical modification after photoinitiated copolymerization of glycidyl methacrylate (GMA) and PEGDA. Important physical and chromatographic properties of the synthesized Monoliths were characterized. The dynamic binding capacities of the three Monoliths (24 mg/mL, 56 mg/mL and 32 mg/mL of column volume, respectively) were comparable or superior to values that have been reported for various other Monoliths. Chromatographic performance was also similar to that provided by a modified poly(GMA-ethylene glycol dimethacrylate) monolith. Separation of standard proteins was achieved under gradient elution conditions using these monolithic columns. Peak capacities of 34, 58 and 36 proteins were obtained with analysis times of 20–30 min. This work represents a successful attempt to prepare functionalized Monoliths via direct copolymerization of monomers with desired functionalities. Compared to earlier publications, additional surface modifications were avoided and the PEGDA crosslinker helped to improve the biocompatibility of the monolithic backbone.
