The Experts below are selected from a list of 7212 Experts worldwide ranked by ideXlab platform
Harald D. H. Stöver - One of the best experts on this subject based on the ideXlab platform.
-
cross linked hydrogels formed through diels alder coupling of furan and maleimide modified poly methyl Vinyl Ether alt maleic acid
Langmuir, 2016Co-Authors: Alison S Stewart, Matilda Backholm, Nicholas A. D. Burke, Harald D. H. StöverAbstract:The Diels–Alder [4 + 2] cycloaddition between furan- and maleimide-functional polyanions was used to form cross-linked synthetic polymer hydrogels. Poly(methyl Vinyl Ether-alt-maleic anhydride) was reacted with furfurylamine or N-(2-aminoethyl)maleimide in acetonitrile to form pairs of furan- and maleimide-functionalized poly(methyl Vinyl Ether-alt-maleic acid)s. Mixtures of these mutually reactive polyanions in water gelled within 15 min to 18 h, depending on degree of functionalization and polymer concentrations. Solution and magic-angle spinning 1H NMR were used to confirm the formation of the Diels–Alder adduct, to analyze competing hydrolytic side reactions, and demonstrate postgelation functionalization. The effect of the degree of furan and maleimide functionalization, polymer concentration, pH, and calcium ion concentration, on gelation time, gel mechanical properties, and equilibrium swelling, are described. Release of dextran as a model drug was studied using fluorescence spectroscopy, as a func...
-
cross linked hydrogels formed through diels alder coupling of furan and maleimide modified poly methyl Vinyl Ether alt maleic acid
Langmuir, 2016Co-Authors: Alison S Stewart, Matilda Backholm, Nicholas A. D. Burke, Harald D. H. StöverAbstract:The Diels-Alder [4 + 2] cycloaddition between furan- and maleimide-functional polyanions was used to form cross-linked synthetic polymer hydrogels. Poly(methyl Vinyl Ether-alt-maleic anhydride) was reacted with furfurylamine or N-(2-aminoethyl)maleimide in acetonitrile to form pairs of furan- and maleimide-functionalized poly(methyl Vinyl Ether-alt-maleic acid)s. Mixtures of these mutually reactive polyanions in water gelled within 15 min to 18 h, depending on degree of functionalization and polymer concentrations. Solution and magic-angle spinning (1)H NMR were used to confirm the formation of the Diels-Alder adduct, to analyze competing hydrolytic side reactions, and demonstrate postgelation functionalization. The effect of the degree of furan and maleimide functionalization, polymer concentration, pH, and calcium ion concentration, on gelation time, gel mechanical properties, and equilibrium swelling, are described. Release of dextran as a model drug was studied using fluorescence spectroscopy, as a function of gel composition and calcium treatment.
Alison S Stewart - One of the best experts on this subject based on the ideXlab platform.
-
cross linked hydrogels formed through diels alder coupling of furan and maleimide modified poly methyl Vinyl Ether alt maleic acid
Langmuir, 2016Co-Authors: Alison S Stewart, Matilda Backholm, Nicholas A. D. Burke, Harald D. H. StöverAbstract:The Diels–Alder [4 + 2] cycloaddition between furan- and maleimide-functional polyanions was used to form cross-linked synthetic polymer hydrogels. Poly(methyl Vinyl Ether-alt-maleic anhydride) was reacted with furfurylamine or N-(2-aminoethyl)maleimide in acetonitrile to form pairs of furan- and maleimide-functionalized poly(methyl Vinyl Ether-alt-maleic acid)s. Mixtures of these mutually reactive polyanions in water gelled within 15 min to 18 h, depending on degree of functionalization and polymer concentrations. Solution and magic-angle spinning 1H NMR were used to confirm the formation of the Diels–Alder adduct, to analyze competing hydrolytic side reactions, and demonstrate postgelation functionalization. The effect of the degree of furan and maleimide functionalization, polymer concentration, pH, and calcium ion concentration, on gelation time, gel mechanical properties, and equilibrium swelling, are described. Release of dextran as a model drug was studied using fluorescence spectroscopy, as a func...
-
cross linked hydrogels formed through diels alder coupling of furan and maleimide modified poly methyl Vinyl Ether alt maleic acid
Langmuir, 2016Co-Authors: Alison S Stewart, Matilda Backholm, Nicholas A. D. Burke, Harald D. H. StöverAbstract:The Diels-Alder [4 + 2] cycloaddition between furan- and maleimide-functional polyanions was used to form cross-linked synthetic polymer hydrogels. Poly(methyl Vinyl Ether-alt-maleic anhydride) was reacted with furfurylamine or N-(2-aminoethyl)maleimide in acetonitrile to form pairs of furan- and maleimide-functionalized poly(methyl Vinyl Ether-alt-maleic acid)s. Mixtures of these mutually reactive polyanions in water gelled within 15 min to 18 h, depending on degree of functionalization and polymer concentrations. Solution and magic-angle spinning (1)H NMR were used to confirm the formation of the Diels-Alder adduct, to analyze competing hydrolytic side reactions, and demonstrate postgelation functionalization. The effect of the degree of furan and maleimide functionalization, polymer concentration, pH, and calcium ion concentration, on gelation time, gel mechanical properties, and equilibrium swelling, are described. Release of dextran as a model drug was studied using fluorescence spectroscopy, as a function of gel composition and calcium treatment.
Sadahito Aoshima - One of the best experts on this subject based on the ideXlab platform.
-
biologically synthesized or bioinspired process derived iron oxides as catalysts for living cationic polymerization of a Vinyl Ether
Chemical Communications, 2012Co-Authors: Arihiro Kanazawa, Shokyoku Kanaoka, Naoki Yagita, Yuya Oaki, Hiroaki Imai, Atsushi Arakaki, Tadashi Matsunaga, Sadahito AoshimaAbstract:Fe3O4 synthesized by magnetotactic bacteria and α-Fe2O3 synthesized via a microbial-mineralization-inspired process functioned as catalysts for the controlled cationic polymerization of a Vinyl Ether.
-
precise synthesis of end functionalized thermosensitive poly Vinyl Ether s by living cationic polymerization
Journal of Polymer Science Part A, 2012Co-Authors: Hiroaki Shimomoto, Shokyoku Kanaoka, Sadahito AoshimaAbstract:A series of poly(2-methoxyethyl Vinyl Ether)s with narrow molecular weight distributions and with perfectly defined end groups of varying hydrophobicities was successfully synthesized by base-assisting living cationic polymerization. The end group was shown to greatly affect the temperature-induced phase separation behavior of aqueous solutions (lower critical solution temperature-type phase separation) or organic solutions (upper critical solution temperature-type phase separation) of the polymers. The cloud points were also influenced largely by the molecular weight and concentration of the polymer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
-
fluorinated Vinyl Ether homopolymers and copolymers living cationic polymerization and temperature induced solubility transitions in various organic solvents including perfluoro solvents
Journal of Polymer Science Part A, 2011Co-Authors: Hiroaki Shimomoto, Dai Fukami, Shokyoku Kanaoka, Sadahito AoshimaAbstract:Partially fluorinated poly(Vinyl Ether)s with C4F9 and C6F12H groups in the side chain were synthesized via living cationic polymerization in the presence of an added base in a fluorine-containing solvent, dichloropentafluoropropanes. For comparison, the polymerization of Vinyl Ether monomers with C2F5 and C6F13 groups and nonfluorinated monomers were also carried out. The characterization of the product polymers using size exclusion chromatography with a fluorinated solvent as an eluent indicated that all polymers had narrow molecular weight distributions (Mw/Mn ∼ 1.1). Interestingly, the moderately fluorinated polymers with C4F9 exhibited upper critical solution temperature-type phase separation in various organic solvents with wide-ranging polarities, whereas highly fluorinated polymers with C6F13 are insoluble in nonfluorinated solvents. Polymers with C4F9 groups exhibited temperature dependent solubility transitions not only in common organic solvents (e.g., toluene, chloroform, tetrahydrofuran, and acetone) but also in perfluoro solvents [e.g., perfluoro(methylcyclohexane) and perfluorodecalin]. On the other hand, the solubility of polymers with C6F12H showed completely different from that of polymers with C6F13, despite their similar fluorine content. In addition, various types of fluorinated block copolymers were prepared in a living manner. The block copolymers with a thermosensitive fluorinated segment underwent temperature-induced micellization and sol–gel transition in various organic solvents. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
-
fluorine containing Vinyl Ether polymers living cationic polymerization in fluorinated solvents as new media and unique solubility characteristics in organic solvents
Journal of Polymer Science Part A, 2011Co-Authors: Hiroaki Shimomoto, Dai Fukami, Shokyoku Kanaoka, Sadahito AoshimaAbstract:Living cationic polymerization of fluorine-containing Vinyl Ethers [CH2CHOC2H4OC3H6CnF2n+1: 5FVE (n = 2), 13FVE (n = 6)] was investigated in various solvents with a CH3CH(OiBu)OCOCH3/Et1.5AlCl1.5 initiating system in the presence of an added base. 5FVE was polymerized quantitatively in toluene at 0 °C, and the obtained polymers had predetermined molecular weights with narrow molecular weight distributions (Mw/Mn < 1.1). On the other hand, for the polymerization of 13FVE, the product polymers precipitated due to their extremely poor solubility in nonfluorinated organic solvents. Therefore, fluorinated solvents such as hydrochlorofluorocarbons, hydrofluorocarbons, hydrofluoroEthers, or α,α,α-trifluorotoluene, as-yet uninvestigated for cationic polymerization, were employed. In these solvents, living polymerization was achieved even with 13FVE, yielding well-defined polymers (Mw/Mn < 1.1, by size exclusion chromatography using a fluorinated solvent as an eluent). The solvents were also shown to be good for living polymerization of isobutyl Vinyl Ether. The obtained fluorine-containing polymers underwent temperature-responsive solubility transitions in organic solvents. Poly(5FVE) showed sensitive upper critical solution temperature (UCST)-type phase separation behavior in toluene. Copolymers of 13FVE and isobutyl Vinyl Ether showed UCST-type phase separation in common organic solvents with different polarities depending on their composition, while a homopolymer of 13FVE was insoluble in all nonfluorinated organic solvents. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
-
Synthesis of Stimuli-Responsive Polymers by Living Polymerization: Poly(N-Isopropylacrylamide) and Poly(Vinyl Ether)s
Advances in Polymer Science, 2007Co-Authors: Sadahito Aoshima, Shokyoku KanaokaAbstract:Precision synthesis via living polymerization has created new possibilities to a variety of stimuli-responsive polymers. This review highlighted the synthesis of poly(N-isopropylacrylamide) [poly(NIPAM)] and poly(Vinyl Ether)s by living polymerization. Poly(NIPAM) is a well-known thermoresponsive polymer, and the related well-defined polymers including block copolymers and end-functionalized polymers have been synthesized intensively throughout the world since the discovery of its living radical polymerization. This recent revolutionary change in the investigations on poly(NIPAM) is first described. Poly(Vinyl Ether)s can be stimuli-responsive with high sensitivity when having certain functional groups. A variety of stimuli-responsive polymers with controlled sequences and/or shapes such as block, gradient copolymers, and star-shaped polymers were designed and synthesized by living cationic polymerization in the presence of an added base. The self-assembling behavior of the obtained polymers is also demonstrated. In addition to the selective synthesis of stimuli-responsive polymers, the recent development of initiating systems for the Vinyl Ether living polymerization by our group is briefly reviewed.
Johann Plank - One of the best experts on this subject based on the ideXlab platform.
-
a study on the impact of different clay minerals on the dispersing force of conventional and modified Vinyl Ether based polycarboxylate superplasticizers
Cement and Concrete Research, 2014Co-Authors: Lei Lei, Johann PlankAbstract:Abstract The impact of three different clay minerals (montmorillonite, kaolinite and muscovite) on the dispersing force of Vinyl-Ether based PCE superplasticizers was studied. At first, a conventional Vinyl-Ether PCE was synthesized from maleic anhydride (MA), mono methoxy poly(ethylene glycol) ester of MA and 4-hydroxy butyl Vinyl Ether (HBVE). Additionally, a PEG-free PCE was prepared by substituting MPEG with hydroxyalkyl groups in the ester. Next, the effect of three different clay minerals on the fluidity of cement paste admixed with both PCEs was investigated. It was found that the conventional PCE is negatively affected by the clays in the order: montmorillonite ≫ kaolinite > muscovite. Whereas, the PEG-free PCEs were only slightly affected. The study suggests that conventional PCEs containing PEG reasonably tolerate all types of clay minerals except montmorillonite. When montmorillonite is present as a contaminant, then use of a PEG-free PCE such as described here presents a viable mitigation strategy.
-
synthesis and properties of a Vinyl Ether based polycarboxylate superplasticizer for concrete possessing clay tolerance
Industrial & Engineering Chemistry Research, 2014Co-Authors: Johann PlankAbstract:Common polycarboxylate Ether (PCE) superplasticizers that possess polyethylene glycol (PEG) graft chains exhibit high sensibility toward clay impurities contained in concrete aggregates and limestone powder. The presence of clay greatly weakens their dispersing ability. In this study, modified Vinyl Ether-based PCEs were synthesized from maleic anhydride (MA) and 4-hydroxy butyl Vinyl Ether (HBVE). We found that successful copolymerization of these two monomers is dependent on incorporation of at least ∼30 wt % of a maleic monoalkyl ester as an auxiliary comonomer. The resulting terpolymers were characterized and tested for their dispersing ability in cement paste in the absence and presence of montmorillonite. The MA–monoalkyl maleate–HBVE terpolymers are little affected by montmorillonite. Sorption measurements and X-ray diffraction analysis suggest that this novel type of PCE interacts with montmorillonite only via surface adsorption, whereas conventional PCEs possessing PEG graft chains incorporate ch...
Karen L. Wooley - One of the best experts on this subject based on the ideXlab platform.
-
a Vinyl Ether functional polycarbonate as a template for multiple postpolymerization modifications
Macromolecules, 2018Co-Authors: Sangho Cho, Gyu Seong Heo, Sarosh Khan, Jessica Huang, David A Hunstad, Mahmoud Elsabahy, Karen L. WooleyAbstract:A highly reactive Vinyl Ether-functionalized aliphatic polycarbonate and its block copolymer were developed as templates for multiple postpolymerization conjugation chemistries. The Vinyl Ether-functional six-membered cyclic carbonate monomer was synthesized by a well-established two-step procedure starting from 2,2-bis(hydroxymethyl)propionic acid. An organobase-catalyzed ring-opening polymerization of the synthesized monomer afforded polycarbonates with pendant Vinyl Ether functionalities (PMVEC). The Vinyl Ether moieties on the resulting polymers were readily conjugated with hydroxyl- or thiol-containing compounds via three different postpolymerization modification chemistries: acetalization, thio-acetalization, and thiol–ene reaction. Acetal-functionalized polycarbonates were studied in depth to exploit their acid-labile acetal functionalities. Acetalization of the amphiphilic diblock copolymer of poly(ethylene glycol) methyl Ether (mPEG) and PMVEC, mPEG113-b-PMVEC13, with the model hydroxyl compound ...
-
A Vinyl Ether-Functional Polycarbonate as a Template for Multiple Postpolymerization Modifications
2018Co-Authors: Sangho Cho, Gyu Seong Heo, Sarosh Khan, Jessica Huang, David A Hunstad, Mahmoud Elsabahy, Karen L. WooleyAbstract:A highly reactive Vinyl Ether-functionalized aliphatic polycarbonate and its block copolymer were developed as templates for multiple postpolymerization conjugation chemistries. The Vinyl Ether-functional six-membered cyclic carbonate monomer was synthesized by a well-established two-step procedure starting from 2,2-bis(hydroxymethyl)propionic acid. An organobase-catalyzed ring-opening polymerization of the synthesized monomer afforded polycarbonates with pendant Vinyl Ether functionalities (PMVEC). The Vinyl Ether moieties on the resulting polymers were readily conjugated with hydroxyl- or thiol-containing compounds via three different postpolymerization modification chemistries: acetalization, thio-acetalization, and thiol–ene reaction. Acetal-functionalized polycarbonates were studied in depth to exploit their acid-labile acetal functionalities. Acetalization of the amphiphilic diblock copolymer of poly(ethylene glycol) methyl Ether (mPEG) and PMVEC, mPEG113-b-PMVEC13, with the model hydroxyl compound 4-methylbenzyl alcohol resulted in a maximum of 42% acetal and 58% hydroxyl side chain groups. Nonetheless, the amphiphilicity of the block polymer allowed for its self-assembly in water to afford nanostructures, as characterized via dynamic light scattering and transmission electron microscopy. The kinetics of acetal cleavage within the block polymer micelles were examined in acidic buffered solutions (pH 4 and 5). In addition, mPEG-b-PMVEC and its hydrolyzed polymer mPEG-b-PMHEC (i.e., after full cleavage of acetals) exhibited minimal cytotoxicity to RAW 264.7 mouse macrophages, indicating that this polymer system represents a biologically nonhazardous material with pH-responsive activity
-
Development of a Vinyl Ether-Functionalized Polyphosphoester as a Template for Multiple Postpolymerization Conjugation Chemistries and Study of Core Degradable Polymeric Nanoparticles
2015Co-Authors: Young H. Lim, Gyu Seong Heo, Mahmoud Elsabahy, Yohannes H. Rezenom, Jeffery E. Raymond, Stephanie Pollack, Karen L. WooleyAbstract:A novel polyphosphoester (PPE) with Vinyl Ether side chain functionality was developed as a versatile template for postpolymerization modifications, and its degradability and biocompatibility were evaluated. An organocatalyzed ring-opening polymerization of ethylene glycol Vinyl Ether-pendant cyclic phosphotriester monomer allowed for construction of poly(ethylene glycol Vinyl Ether phosphotriester) (PEVEP). This Vinyl Ether-functionalized PPE scaffold was coupled with hydroxyl- or thiol-containing model small molecules via three different types of conjugation chemistriesthiol–ene “click” reaction, acetalization, or thio-acetalization reactionto afford modified polymers that accommodated either stable thio–Ether or hydrolytically labile acetal or thio–acetal linkages. Amphiphilic diblock copolymers of poly(ethylene glycol) and PEVEP formed well-defined micelles with a narrow and monomodal size distribution in water, as confirmed by dynamic light scattering (DLS), transmission electron microscopy, and atomic force microscopy. The stability of the micelles and the hydrolytic degradability of the backbone and side chains of the PEVEP block segment were assessed by DLS and nuclear magnetic resonance spectroscopy (1H and 31P), respectively, in aqueous buffer solutions at pH values of 5.0 and 7.4 and at temperatures of 25 and 37 °C. The hydrolytic degradation products of the PEVEP segments of the block copolymers were then identified by electrospray ionization, gas chromatography, and matrix-assisted laser desorption/ionization mass spectrometry. The parent micelles and their degradation products were found to be non-cytotoxic at concentrations up to 3 mg/mL, when evaluated with RAW 264.7 mouse macrophages and OVCAR-3 human ovarian adenocarcinoma cells
-
Development of a Vinyl Ether-Functionalized Polyphosphoester as a Template for Multiple Postpolymerization Conjugation Chemistries and Study of Core Degradable Polymeric Nanoparticles.
Macromolecules, 2014Co-Authors: Young H. Lim, Gyu Seong Heo, Mahmoud Elsabahy, Yohannes H. Rezenom, Stephanie F. Pollack, Jeffery E. Raymond, Karen L. WooleyAbstract:A novel polyphosphoester (PPE) with Vinyl Ether side chain functionality was developed as a versatile template for postpolymerization modifications, and its degradability and biocompatibility were evaluated. An organocatalyzed ring-opening polymerization of ethylene glycol Vinyl Ether-pendant cyclic phosphotriester monomer allowed for construction of poly(ethylene glycol Vinyl Ether phosphotriester) (PEVEP). This Vinyl Ether-functionalized PPE scaffold was coupled with hydroxyl- or thiol-containing model small molecules via three different types of conjugation chemistries—thiol–ene “click” reaction, acetalization, or thio-acetalization reaction—to afford modified polymers that accommodated either stable thio–Ether or hydrolytically labile acetal or thio–acetal linkages. Amphiphilic diblock copolymers of poly(ethylene glycol) and PEVEP formed well-defined micelles with a narrow and monomodal size distribution in water, as confirmed by dynamic light scattering (DLS), transmission electron microscopy, and at...
