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Shengxiang Jiang - One of the best experts on this subject based on the ideXlab platform.
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novel double confined polymeric ionic liquids as sorbents for solid phase microextraction with enhanced stability and durability in high ionic strength solution
Journal of Chromatography A, 2012Co-Authors: Juanjuan Feng, Min Sun, Xia Liu, Shuai Wang, Shengxiang JiangAbstract:Because of the occurrence of ion exchange between high-ionic-strength solution and anions of polymeric ionic liquids (PILs), PILs based solid-phase microextraction (SPME) fibers were rarely used in direct immersion mode to high-salt-added samples. In this work, a novel double-confined PIL sorbent was prepared by co-polymerization of cation and anion of 1-vinyl-3-octylimidzaolium p-styrenesulfonate (VOIm+SS−). The poly(VOIm+-SS−) was chemically bonded onto functionalized stainless steel wire via surface radical Chain-Transfer Reaction. Stability of poly(VOIm+-SS−) in high-ionic-strength solution was investigated and compared with that of poly(1-vinyl-3-octylimidzaolium benzenesulfonate) (poly(VOIm+BS−)) by elemental analysis of sulfur element, and results turned out that the poly(VOIm+-SS−) was more stable. Coupled to gas chromatography (GC), the poly(VOIm+-SS−) fiber was used to extract three sorts of compounds including anilines, phenols and phthalate esters in aqueous solution. The as-established method showed good linearity, low detection limits, and acceptable repeatability. The direct immersion SPME-GC method was applied to determine the model phthalate esters in bottled mineral water. The determination results were satisfactory.
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a novel aromatically functional polymeric ionic liquid as sorbent material for solid phase microextraction
Journal of Chromatography A, 2012Co-Authors: Juanjuan Feng, Min Sun, Xia Liu, Shengxiang JiangAbstract:Abstract Physical and chemical properties of ionic liquids (ILs) are significantly affected by types of their cations and anions. In this paper, a novel aromatically functional 1-vinyl-3-octylimidazolium 2-naphthalene-sulfonate salt was synthesized through metathesis Reaction between 1-vinyl-3-octylimidazolium bromide and sodium 2-naphthalene-sulfonate, and polymerized onto the stainless steel wire in situ via surface radical Chain-Transfer Reaction. Octanol/water distribution coefficient of the ionic liquid was studied and compared with that of 1-vinyl-3-octylimidazolium hexafluorophosphate. Partition coefficients of polycyclic aromatic hydrocarbons (PAHs) on these two polymeric ionic liquids-coated fibers indicated the enhanced hydrophobicity and aromaticity of the target IL. Analytical parameters exhibited high extraction efficiency of the novel fiber. Calibration ranges for several PAHs were from 0.02 to 200 μg L −1 . Limits of detection (LODs) were ranged from 0.005 to 0.01 μg L −1 . Application reliability of the proposed fiber was also investigated with some phthalate ester plasticizers. LODs were ranged from 0.02 to 0.05 μg L −1 . Hair spray and nail polish were used as real samples, and di-n-butyl phthalate and di-(2-ethyl-hexyl) phthalate were quantified with the established method.
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chromatographic characteristics of poly 1 vinylimidazole grafted silica in normal phase hplc
IEEE Journal of Solid-state Circuits, 2011Co-Authors: Juanjuan Feng, Xusheng Wang, Shengxiang JiangAbstract:A stationary phase based on poly(1-vinylimidazole)-grafted silica has been prepared by the surface radical Chain-Transfer Reaction. The stationary phase was characterized by infrared spectra, X-ray photoelectron spectroscopy and elemental analysis. Chromatographic characteristics of the stationary phase were investigated in normal-phase HPLC. The results showed that both weak polar compounds (polycyclic aromatic hydrocarbons, dialkyl phthalates) and polar compounds (anilines, phenols) could be successfully separated on this stationary phase, implying better separation performance than blank silica and conventional aminopropyl-bonded silica under the same conditions. The excellent performance can be attributed to multiple interactions between surface modifier and the analytes that might include dipole, hydrogen bonding, H-π, electrostatic and inductive interactions.
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Preparation and characterization of silica confined ionic liquids as chromatographic stationary phases through surface radical Chain-Transfer Reaction
The Analyst, 2008Co-Authors: Hongdeng Qiu, Xia Liu, Licheng Wang, Shengxiang JiangAbstract:Ionic liquids (ILs) have been used in various regions of chemistry. Ionic liquids have designability, thus giving us the ability to manipulate the structure (with respect to the organic cation, inorganic anion and the length of the side Chain attached to the organic cation) and consequently their properties. In this manuscript, two new different chromatographic stationary phases based on different ionic liquid-modified silica particles were prepared through surface radical Chain-Transfer Reaction and characterized with elemental analysis, Raman spectroscopy and X-ray photoelectron spectroscopy. 1-Allyl-3-butylimidazolium ionic liquid-modified silica particles can be used as a strong anion-exchange stationary phase. 1-Allyl-3-(butyl-4-sulfonate)imidazolium ionic liquid-modified silica particles were used for the first time as the covalently bonded charge-balanced zwitterionic stationary phase in electrostatic ion chromatography for the simultaneous separation of inorganic anions and cations with pure water as the mobile phase.
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surface confined radical Chain Transfer the intermediate Reaction for chemically attaching polymer films on porous silica for chromatographic application
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2004Co-Authors: Shujuan Liu, Feng Zhou, Shengxiang JiangAbstract:Surface-confined Chain Transfer Reaction in free radical polymerization of different monomers leads to polymer-grafted silica particles. Porous silica is selected as the carrier of potential thiol Chain Transfer groups and as stationary phase in high-performance liquid chromatography (HPLC). The thiol-terminated silica and polymer over-layer-modified silica are characterized by FT-IR and Raman spectra. The chemical composite and the grafting amount of polymer on silica surface are measured by X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), etc. The grafting amount of polymer on silica surface and the molecular weight of free polymer formed in bulk solution decrease with the addition of thiol-terminated silica coincide with each other. The obtained polymethylmethacrylate (PMMA)-modified silica exhibits excellent separation capacity for three series of selected compounds, i.e. aromatic compounds and alkaloids, and displays the reversed-phase separation mechanism.
Paulette Spencer - One of the best experts on this subject based on the ideXlab platform.
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the influence of water on visible light initiated free radical cationic ring opening hybrid polymerization of methacrylate epoxy polymerization kinetics crosslinking structure and dynamic mechanical properties
RSC Advances, 2015Co-Authors: Linyong Song, Anil Misra, Paulette SpencerAbstract:The objective of this study was to determine the influence of water on the polymerization kinetics, crosslinking structure and dynamic mechanical properties of methacrylate/epoxy polymers cured by visible-light initiated free-radical/cationic ring-opening hybrid polymerization. Water-containing formulations were prepared by adding ~4-7 wt% D2O depending on the water miscibility of monomer resins. The water-containing adhesives were compared with the adhesives photo-cured in the absence of water. The results show an improved degree of conversion for both methacrylates and epoxy by adding water. The rate of the epoxy cationic ring-opening Reaction is increased while the rate of free radical polymerization is decreased in the presence of water. The decreased crosslinking density noted in the presence of water suggests that the Chain Transfer Reaction between water and epoxy competes with the hydroxyl-based Chain Transfer mechanism. There is potential application of this visible-light initiated hybrid polymerization in biomaterials, e.g. dental restorations and tissue engineering scaffolds.
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visible light initiated free radical cationic ring opening hybrid photopolymerization of methacrylate epoxy polymerization kinetics crosslinking structure and dynamic mechanical properties
Macromolecular Chemistry and Physics, 2015Co-Authors: Linyong Song, Anil Misra, Paulette SpencerAbstract:The effects of polymerization kinetics and chemical miscibility on the crosslinking structure and mechanical properties of polymers cured by visible-light initiated free-radical/cationic ring-opening hybrid photopolymerization are determined. A three-component initiator system is used and the monomer system contains methacrylates and epoxides. The photopolymerization kinetics is monitored in situ by Fourier transform infrared-attenuated total reflectance. The crosslinking structure is studied by modulated differential scanning calorimetry and dynamic mechanical analysis. X-ray microcomputed tomography is used to evaluate microphase separation. The mechanical properties of polymers formed by hybrid polymerization are comparable to the control formed by free-radical polymerization. These investigations mark the first time that the benefits of the Chain Transfer Reaction between epoxy and hydroxyl groups of methacrylate, on the crosslinking network and microphase separation during hybrid visible-light initiated photopolymerization, have been determined.
Jin-yong Dong - One of the best experts on this subject based on the ideXlab platform.
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catalytic synthesis of styryl capped isotactic polypropylenes
Journal of Polymer Science Part A, 2010Co-Authors: Huahua Huang, Hui Niu, Chengang Cao, Jin-yong DongAbstract:Bis-styrenic molecules, 1,4-divinylbenzene (DVB) and 1,2-bis(4-vinylphenyl)ethane (BVPE), were successfully combined with hydrogen (H2) to form consecutive Chain Transfer complexes in propylene polymerization mediated by an isospecific metallocene catalyst (i.e., rac-dimethylsilylbis(2-methyl-4-phenylindenyl)zirconium dichloride, I) activated with methylaluminoxane (MAO), rendering a catalytic access to styryl-capped isotactic polypropylenes (i-PP). The Chain Transfer Reaction took place in a unique way where prior to the ultimate Chain Transfer DVB/H2 or BVPE/H2 caused a copolymerization-like Reaction leading to the formation of main Chain benzene rings. A preemptive polymer Chain reinsertion was deduced after the consecutive actions of DVB/H2 or BVPE/H2, which gave the styryl-terminated polymer Chain alongside a metal-hydride active species. It was confirmed that the Chain reinsertion occurred in a regio-irregular 1,2-fashion, which contrasted with a normal 2,1-insertion of styrene monomer and ensured subsequent continuous propylene insertions, directing the polymerization to repeated DVB or BVPE incorporations inside polymer Chain. Only as a competitive Reaction, the insertion of propylene into metal-hydride site broke the Chain propagation resumption process while completed the Chain Transfer process by releasing the styryl-terminated polymer Chain. BVPE was found with much higher Chain Transfer efficiency than DVB, which was attributed to its non-conjugated structure with much divided styrene moieties resulting in higher polymerization reactivity but lower Chain reinsertion tendency. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3709–3713, 2010
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Borane Chain Transfer Reaction in olefin polymerization using trialkylboranes as Chain Transfer agents
Journal of Polymer Science Part A: Polymer Chemistry, 2010Co-Authors: Wentian Lin, Hui Niu, T. C. Mike Chung, Jin-yong DongAbstract:This article discusses a new borane Chain Transfer Reaction in olefin polymerization that uses trialkylboranes as a Chain Transfer agent and thus can be realized in conventional single site polymerization processes under mild conditions. Commercially available triethylborane (TEB) and synthesized methyl-B-9-borabicyclononane (Me-B-9-BBN) were engaged in metallocene/MAO [depleted of trimethylaluminum (TMA)]-catalyzed ethylene (Cp2ZrCl2 and rac-Me2Si(2-Me-4-Ph)2ZrCl2 as a catalyst) and styrene (Cp*Ti(OMe)3 as catalyst) polymerizations. The two trialkylboranes were found—in most cases—able to initiate an effective Chain Transfer Reaction, which resulted in hydroxyl (OH)-terminated PE and s-PS polymers after an oxidative workup process, suggesting the formation of the B-polymer bond at the polymer Chain end. However, Chain Transfer efficiencies were influenced substantially by the steric hindrances of both the substituent on the trialkylborane and that on the catalyst ligand. TEB was more effective than TMA in ethylene polymerization with Cp2ZrCl2/MAO, whereas it became less effective when the catalyst changed to rac-Me2Si(2-Me-4-Ph)2ZrCl2. Both TEB and Me-B-9-BBN caused an efficient Chain Transfer in the Cp2ZrCl2/MAO-catalyzed ethylene polymerization; nevertheless, Me-B-9-BBN failed in vain with rac-Me2Si(2-Me-4-Ph)2ZrCl2/MAO. In the case of styrene polymerization with Cp*Ti(OMe)3/MAO, thanks to the large steric openness of the catalyst, TEB exhibited a high efficiency of Chain Transfer. Overall, trialkylboranes as Chain Transfer agents perform as well as BH-bearing borane derivatives, and are additionally advantaged by a much milder Reaction condition, which further boosts their applicability in the preparation of borane-terminated polyolefins. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3534–3541, 2010
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a new synthetic route to borane terminated isotactic polypropylenes via styrene hydrogen consecutive Chain Transfer Reaction
Journal of Polymer Science Part A, 2006Co-Authors: Guoqiang Fan, Jin-yong Dong, Zhigang Wang, T C ChungAbstract:This paper discusses a new process of preparing borane-terminated isotactic polypropylenes (i-PPs) via in situ Chain Transfer Reaction, which avoids the use of B-H-containing Chain Transfer agent and thus can be carried out with Al-activated metallocene catalyst under mild Reaction conditions. The chemistry centers on a consecutive Chain Transfer Reaction, first to a trialkylborane-containing styrene derivative, 4-[B-(n-butylene)-9-BBN]styrene (B-styrene), then to hydrogen in the isoselective polymerization of propylene catalyzed by rac-Me2Si(2-Me-4-Ph-Ind)2ZrCl2/MAO. The borane-terminated i-PP thus obtained keeps the desired properties of a polymeric alkyl-9-BBN reagent and was used to initiate radical polymerization of methyl methacrylate (MMA) to prepare i-PP-b-PMMA diblock copolymer. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 539–548, 2006
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an examination of aluminum Chain Transfer Reaction in rac me2si 2 me 4 naph ind 2zrcl2 mao catalyzed propylene polymerization and synthesis of aluminum terminated isotactic polypropylene with controlled molecular weight
Journal of Molecular Catalysis A-chemical, 2005Co-Authors: Guoqiang Fan, Jin-yong DongAbstract:Abstract Chain Transfer to the aluminum cocatalyst was found to be the predominant Chain Transfer Reaction in propylene polymerization mediated by the sterically hindered, highly isospecific rac -dimethylsilanediylbis(2-methyl-4-naphthyl)indenyl-zirconium dichloride ( rac -Me 2 Si[2-Me-4-Naph-Ind] 2 ZrCl 2 )/methylaluminoxane (MAO) catalyst system. By finely tuning the polymerization conditions including the polymerization temperature and Al/Zr ratio, this predominant aluminum Transfer Reaction was directed to prepare aluminum-terminated isotactic polypropylene ( i -PP) with high end-group selectivity and controlled and narrowly distributed molecular weight.
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synthesis of isotactic polypropylene containing a terminal cl oh or nh2 group via metallocene mediated polymerization Chain Transfer Reaction
Macromolecules, 2002Co-Authors: Jin-yong Dong, Z M Wang, H Hong, T C ChungAbstract:This paper discusses a direct (one-pot) polymerization process to prepare isotactic polypropylene (i-PP) having a terminal functional group including Cl, OH, and NH2. The chemistry involves metallocene-mediated propylene polymerization using rac-Me2Si[2-Me-4-Ph(Ind)]2ZrCl2/MAO complex in the presence of styrene derivatives (St−f), carrying a Cl (St−Cl) or a silane-protected OH (St−OSi) or a silane-protected NH2 (St−NSi2), followed by hydrogenation. Apparently, the propylene propagating Chain end engages in a facile consecutive Chain Transfer Reaction, reacting with St−f and then hydrogen, with high catalyst reactivity under the proper St−f and hydrogen concentrations. The polymer molecular weight was inversely proportional to the molar ratio of [St−f]/[propylene] with a Chain Transfer constant (ktr/kp) of 1/21 for St−Cl, 1/34 for St−NSi2, and 1/48 for St−OSi, respectively. Both silane protecting groups were hydrolyzed in acidic aqueous solution during the sample workup step to obtain the desirable i-PP po...
Linyong Song - One of the best experts on this subject based on the ideXlab platform.
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the influence of water on visible light initiated free radical cationic ring opening hybrid polymerization of methacrylate epoxy polymerization kinetics crosslinking structure and dynamic mechanical properties
RSC Advances, 2015Co-Authors: Linyong Song, Anil Misra, Paulette SpencerAbstract:The objective of this study was to determine the influence of water on the polymerization kinetics, crosslinking structure and dynamic mechanical properties of methacrylate/epoxy polymers cured by visible-light initiated free-radical/cationic ring-opening hybrid polymerization. Water-containing formulations were prepared by adding ~4-7 wt% D2O depending on the water miscibility of monomer resins. The water-containing adhesives were compared with the adhesives photo-cured in the absence of water. The results show an improved degree of conversion for both methacrylates and epoxy by adding water. The rate of the epoxy cationic ring-opening Reaction is increased while the rate of free radical polymerization is decreased in the presence of water. The decreased crosslinking density noted in the presence of water suggests that the Chain Transfer Reaction between water and epoxy competes with the hydroxyl-based Chain Transfer mechanism. There is potential application of this visible-light initiated hybrid polymerization in biomaterials, e.g. dental restorations and tissue engineering scaffolds.
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visible light initiated free radical cationic ring opening hybrid photopolymerization of methacrylate epoxy polymerization kinetics crosslinking structure and dynamic mechanical properties
Macromolecular Chemistry and Physics, 2015Co-Authors: Linyong Song, Anil Misra, Paulette SpencerAbstract:The effects of polymerization kinetics and chemical miscibility on the crosslinking structure and mechanical properties of polymers cured by visible-light initiated free-radical/cationic ring-opening hybrid photopolymerization are determined. A three-component initiator system is used and the monomer system contains methacrylates and epoxides. The photopolymerization kinetics is monitored in situ by Fourier transform infrared-attenuated total reflectance. The crosslinking structure is studied by modulated differential scanning calorimetry and dynamic mechanical analysis. X-ray microcomputed tomography is used to evaluate microphase separation. The mechanical properties of polymers formed by hybrid polymerization are comparable to the control formed by free-radical polymerization. These investigations mark the first time that the benefits of the Chain Transfer Reaction between epoxy and hydroxyl groups of methacrylate, on the crosslinking network and microphase separation during hybrid visible-light initiated photopolymerization, have been determined.
Hongdeng Qiu - One of the best experts on this subject based on the ideXlab platform.
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surface radical Chain Transfer Reaction in deep eutectic solvents for preparation of silica grafted stationary phases in hydrophilic interaction chromatography
Talanta, 2017Co-Authors: Beibei Yang, Hongdeng Qiu, Ming Guan, Tianpei CaiAbstract:In this paper, deep eutectic solvents (DESs) were firstly used as new and green solvents for the preparation of polymer-grafted silica stationary phases. 1-Vinylimidazole and acrylic acid were homopolymerized and copolymerized on silica via surface radical Chain-Transfer Reaction in the DESs. Three stationary phases including poly(1-vinylimidazole)-, poly(acrylic acid)-, poly(1-vinylimidazole-co-acrylic acid)-grafted silica were obtained and characterized by elemental analysis and Fourier transform infrared spectroscopy. Their hydrophilic interaction chromatographic properties were investigated for separation of nucleosides, nucleobases, saccharides and amino acids. The retention changes of nucleosides and nucleobases on these columns were investigated under different chromatographic conditions including acetonitrile content, salt concentration, pH of mobile phase and column temperature. The repeatability of these columns was also investigated. The results demonstrate that DESs can be used as new media for the synthesis of silica-based stationary phases by homopolymerization and copolymerization on the surface of porous silica particles.
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Preparation and characterization of silica confined ionic liquids as chromatographic stationary phases through surface radical Chain-Transfer Reaction
The Analyst, 2008Co-Authors: Hongdeng Qiu, Xia Liu, Licheng Wang, Shengxiang JiangAbstract:Ionic liquids (ILs) have been used in various regions of chemistry. Ionic liquids have designability, thus giving us the ability to manipulate the structure (with respect to the organic cation, inorganic anion and the length of the side Chain attached to the organic cation) and consequently their properties. In this manuscript, two new different chromatographic stationary phases based on different ionic liquid-modified silica particles were prepared through surface radical Chain-Transfer Reaction and characterized with elemental analysis, Raman spectroscopy and X-ray photoelectron spectroscopy. 1-Allyl-3-butylimidazolium ionic liquid-modified silica particles can be used as a strong anion-exchange stationary phase. 1-Allyl-3-(butyl-4-sulfonate)imidazolium ionic liquid-modified silica particles were used for the first time as the covalently bonded charge-balanced zwitterionic stationary phase in electrostatic ion chromatography for the simultaneous separation of inorganic anions and cations with pure water as the mobile phase.