The Experts below are selected from a list of 2577 Experts worldwide ranked by ideXlab platform
Henri Cramail - One of the best experts on this subject based on the ideXlab platform.
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Bio-Based Thermo-Reversible Aliphatic Polycarbonate Network
Molecules, 2020Co-Authors: Pierre-luc Durand, Etienne Grau, Henri CramailAbstract:Aliphatic Polycarbonates represent an important class of materials with notable applications in the biomedical field. In this work, low Tg furan-functionalized bio-based aliphatic Polycarbonates were cross-linked thanks to the Diels-Alder (DA) reaction with a bis-maleimide as the cross-linking agent. The thermo-reversible DA reaction allowed for the preparation of reversible cross-linked polycarbonate materials with tuneable properties as a function of the pendent furan content that was grafted on the polycarbonate backbone. The possibility to decrosslink the network around 70 °C could be an advantage for biomedical applications, despite the rather poor thermal stability of the furan-functionalized cross-linked Polycarbonates.
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Simple and Efficient Approach toward Photosensitive Biobased Aliphatic Polycarbonate Materials
2018Co-Authors: Pierre-luc Durand, Etienne Grau, Antoine Brège, Guillaume Chollet, Henri CramailAbstract:Fatty acids were used as precursors for the synthesis of photosensitive polycarbonate materials. In order to avoid multistep reactions, a simple and straightforward methodology toward the synthesis of photosensitive monomers has been developed. Hence, a fatty acid–based cyclic carbonate bearing an unsaturation was synthesized and subsequently polymerized in a controlled manner (Đ = 1.07) by organo-catalyzed ring-opening polymerization (ROP). A thio-cinnamate derivative was then readily synthesized via a one-pot reaction and grafted onto the polycarbonate backbone by thiol–ene reaction. The content of photoresponsive cinnamoyl moiety grafted on the polycarbonate was tunable with the reaction time. Such functionalized Polycarbonates could be crosslinked (by UV irradiation at 365 nm) and partially decrosslinked (irradiated at 254 nm) and exhibit versatile properties ranging from rather tough materials to elastomeric networks with respect to the content of the photosensitive cinnamoyl moiety grafted on the polymer
Donald J. Darensbourg - One of the best experts on this subject based on the ideXlab platform.
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construction of autonomic self healing co2 based Polycarbonates via one pot tandem synthetic strategy
Macromolecules, 2018Co-Authors: Guan-wen Yang, Yao-yao Zhang, Yanyan Wang, Donald J. DarensbourgAbstract:The coupling of epoxides and carbon dioxide to Polycarbonates (CO2–PCs) has been the subject of intense research for nearly half a century. Although tremendous progress has been achieved, their aliphatic characteristics and lack of functionalities of CO2–PCs limit the scope of their application in high value-added and functional materials. In this article, the first CO2-based polycarbonate with the ability to autonomously self-heal is constructed via a one-pot synthetic strategy. The key to the success of the synthetic strategy is efficient tandem three different catalytic reactions, i.e., hydrolysis of epoxides, immortal copolymerization of CO2/epoxides, and thiol–ene click reactions in a one-pot process. Based on the standard tensile testing, these CO2-based materials show robust self-healing properties, where the extensibility, maximal strength, and Young’s modulus of the specimens can almost entirely recover to their original value under ambient temperature. Our studies demonstrate that the self-heali...
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Construction of Autonomic Self-Healing CO2‑Based Polycarbonates via One-Pot Tandem Synthetic Strategy
2018Co-Authors: Guan-wen Yang, Yao-yao Zhang, Yanyan Wang, Donald J. DarensbourgAbstract:The coupling of epoxides and carbon dioxide to Polycarbonates (CO2–PCs) has been the subject of intense research for nearly half a century. Although tremendous progress has been achieved, their aliphatic characteristics and lack of functionalities of CO2–PCs limit the scope of their application in high value-added and functional materials. In this article, the first CO2-based polycarbonate with the ability to autonomously self-heal is constructed via a one-pot synthetic strategy. The key to the success of the synthetic strategy is efficient tandem three different catalytic reactions, i.e., hydrolysis of epoxides, immortal copolymerization of CO2/epoxides, and thiol–ene click reactions in a one-pot process. Based on the standard tensile testing, these CO2-based materials show robust self-healing properties, where the extensibility, maximal strength, and Young’s modulus of the specimens can almost entirely recover to their original value under ambient temperature. Our studies demonstrate that the self-healing capability of these CO2-based materials arises both from the homo-hydrogen bonding (between amide groups) and the hetero-hydrogen bonding (between amide group and carbonate group of polycarbonate backbone). The convenient and atom economic synthesis strategy, combined with the impressive self-healing capability for these materials, should expand the library of high value-added CO2-based Polycarbonates and the scope of their applications
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construction of versatile and functional nanostructures derived from co2 based Polycarbonates
Angewandte Chemie, 2015Co-Authors: Yanyan Wang, Jingwei Fan, Donald J. DarensbourgAbstract:The construction of amphiphilic Polycarbonates through epoxides/CO2 coupling is a challenging aim to provide more diverse CO2 -based functional materials. In this report, we demonstrate the facile preparation of diverse and functional nanoparticles derived from a CO2 -based triblock polycarbonate system. By the judicious use of water as chain-transfer reagent in the propylene oxide/CO2 polymerization, poly(propylene carbonate (PPC) diols are successfully produced and serve as macroinitiators in the subsequent allyl glycidyl ether/CO2 coupling reaction. The resulting ABA triblock polycarbonate can be further functionalized with various thiols by radical mediated thiol-ene click chemistry, followed by self-assembly in deionized water to construct a versatile and functional nanostructure system. This class of amphiphilic Polycarbonates could embody a powerful platform for biomedical applications.
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Postpolymerization Functionalization of Copolymers Produced from Carbon Dioxide and 2‑Vinyloxirane: Amphiphilic/Water-Soluble CO2‑Based Polycarbonates
2014Co-Authors: Donald J. Darensbourg, Fu-te TsaiAbstract:Common CO2-based Polycarbonates are known to be highly hydrophobic, and this “inert” property makes them difficult for the covalent immobilization of bioactive molecules. A practical method for modifying polymers is to introduce various functional groups that permit decoration of polymer chains with bioactive substances. In this report, CO2-based poly(2-vinyloxirane carbonate) (PVIC) with more than 99% carbonate linkages is isolated from the CO2/2-vinyloxirane alternating copolymerization catalyzed by the bifunctional catalyst [(1R,2R)-SalenCo(III)(DNP)2] (1) (DNP = 2,4-dinitrophenolate) bearing a quaternary ammonium salt on the ligand framework. It was also observed that the presence of propylene oxide significantly activates 2-vinyloxirane for incorporation into the polymer chain as well as inhibits the formation of cyclic carbonate in the terpolymerization process. DSC studies demonstrate that the glass transition temperature (Tg) decreases with the increase in the content of vinyl groups in the polycarbonate. By way of thiol–ene coupling, showing mainly “click” characteristics and nearly quantitative yields, amphiphilic Polycarbonates (PVIC-OH and PVIC-COOH) with multiple hydroxy or carboxy functionalities have been prepared, providing suitable reactivities for further modifications (ring-opening of l-aspartic acid anhydride hydrochloride salt and deprotonation by aqueous ammonium hydroxide (NH4OH(aq))) to successfully isolate the water-soluble CO2-based polycarbonate PVIC-COONH4, and the PVIC-OH-Asp polymer which shows particles dispersed in water with an average hydrodynamic diameter Dn = 32.2 ± 8.8 nm. It is presumed that this emerging class of amphiphilic/water-soluble Polycarbonates could embody a powerful platform for bioconjugation and drug conjugation. In contrast to lower Tgs of PVIC, (PVIC-co-PC), PVIC-OH, and PVIC-COOH, the Polycarbonates PVIC-OH-Asp and PVIC-COONH4 show higher Tgs as a consequence of their intrinsic ionic property (ammonium salts)
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carbon dioxide epoxide coupling reactions utilizing lewis base adducts of zinc halides as catalysts cyclic carbonate versus polycarbonate production
Inorganic Chemistry, 2003Co-Authors: Donald J. Darensbourg, Samuel J Lewis, Jody L Rodgers, Jason C YarbroughAbstract:The reactions of zinc halides with 2,6-di-methoxypyridine or 3-trifluoromethylpyridine in dichloromethane have led to the formation of quite different complexes. Specifically, reactions involving pyridine containing electron donating methoxy substituents have provided salts of the type [Zn(2,6-dimethoxypyridine)4][Zn2X6], as revealed by elemental analysis and X-ray crystallography. On the other hand, simple bis-pyridine adducts of zinc halides were isolated from the reactions involving the pyridine ligand with electron withdrawing substituents and characterized by X-ray crystallography, for example, Zn(3-trifluoromethylpyridine)2Br2. These zinc complexes were shown to be catalytically active for the coupling of carbon dioxide and epoxides to provide high molecular weight Polycarbonates and cyclic carbonates, with the order of reactivity being Cl ≥ Br > I, and 2,6-di-methoxypyridine > 3-trifluoromethylpyridine. Polycarbonate production from carbon dioxide and cyclohexene oxide was shown to be first-order i...
Karen L. Wooley - One of the best experts on this subject based on the ideXlab platform.
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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 ...
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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
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Polycarbonates derived from glucose via an organocatalytic approach
Journal of the American Chemical Society, 2013Co-Authors: Koichiro Mikami, Alexander T Lonnecker, Tiffany P Gustafson, Nathanael F Zinnel, Peijing Pai, David H Russell, Karen L. WooleyAbstract:An organocatalyzed ring-opening polymerization methodology was developed for the preparation of Polycarbonates derived from glucose as a natural product starting material. The cyclic 4,6-carbonate monomer of glucose having the 1, 2, and 3 positions methyl-protected was prepared in three steps from a commercially available glucose derivative, and the structure was confirmed by means of NMR and IR spectroscopies, electrospray ionization mass spectrometry (MS), and single-crystal X-ray analysis. Polymerization of the monomer, initiated by 4-methylbenzyl alcohol in the presence of 1,5,7-triazabicyclo[4.4.0]dec-5-ene as the organocatalyst, proceeded effectively in a controlled fashion to afford the polycarbonate with a tunable degree of polymerization, narrow molecular weight distribution, and well-defined end groups, as confirmed by a combination of NMR spectroscopy, gel-permeation chromatography, and MALDI-TOF MS. A distribution of head-to-head, head-to-tail, and tail-to-tail regiochemistries was determined ...
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Synthesis and Characterization of Hyperbranched Polycarbonates
Macromolecules, 1997Co-Authors: Daniel H. Bolton, Karen L. WooleyAbstract:Hyperbranched aromatic Polycarbonates were prepared by the polymerization of an A2B monomer derived from 1,1,1-tris(4‘-hydroxyphenyl)ethane. Protection of one of the three phenols of the triphenol by a tert-butyldimethylsilyl group was followed by conversion of the remaining two phenolic groups to carbonylimidazolide functionalities to give the A2B monomer. Polymerization was accomplished via the anhydrous removal of the silicon protecting group and subsequent reaction of the phenoxide with a carbonylimidazolide moiety to yield the hyperbranched aryl polycarbonate bearing carbonylimidazolide chain ends. Subsequent cleavage of these end groups by reaction with methanol upon precipitation, yielded the phenol-terminated hyperbranched polycarbonate. Silylation of the phenol-terminated material with tert-butyldimethylsilyl chloride, followed by degradation of the carbonate linkages by reaction with lithium aluminum hydride and analysis of the products by HPLC allowed for the degree of branching to be determine...
Pierre-luc Durand - One of the best experts on this subject based on the ideXlab platform.
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Bio-Based Thermo-Reversible Aliphatic Polycarbonate Network
Molecules, 2020Co-Authors: Pierre-luc Durand, Etienne Grau, Henri CramailAbstract:Aliphatic Polycarbonates represent an important class of materials with notable applications in the biomedical field. In this work, low Tg furan-functionalized bio-based aliphatic Polycarbonates were cross-linked thanks to the Diels-Alder (DA) reaction with a bis-maleimide as the cross-linking agent. The thermo-reversible DA reaction allowed for the preparation of reversible cross-linked polycarbonate materials with tuneable properties as a function of the pendent furan content that was grafted on the polycarbonate backbone. The possibility to decrosslink the network around 70 °C could be an advantage for biomedical applications, despite the rather poor thermal stability of the furan-functionalized cross-linked Polycarbonates.
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Simple and Efficient Approach toward Photosensitive Biobased Aliphatic Polycarbonate Materials
2018Co-Authors: Pierre-luc Durand, Etienne Grau, Antoine Brège, Guillaume Chollet, Henri CramailAbstract:Fatty acids were used as precursors for the synthesis of photosensitive polycarbonate materials. In order to avoid multistep reactions, a simple and straightforward methodology toward the synthesis of photosensitive monomers has been developed. Hence, a fatty acid–based cyclic carbonate bearing an unsaturation was synthesized and subsequently polymerized in a controlled manner (Đ = 1.07) by organo-catalyzed ring-opening polymerization (ROP). A thio-cinnamate derivative was then readily synthesized via a one-pot reaction and grafted onto the polycarbonate backbone by thiol–ene reaction. The content of photoresponsive cinnamoyl moiety grafted on the polycarbonate was tunable with the reaction time. Such functionalized Polycarbonates could be crosslinked (by UV irradiation at 365 nm) and partially decrosslinked (irradiated at 254 nm) and exhibit versatile properties ranging from rather tough materials to elastomeric networks with respect to the content of the photosensitive cinnamoyl moiety grafted on the polymer
James L Hedrick - One of the best experts on this subject based on the ideXlab platform.
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disease directed design of biodegradable polymers reactive oxygen species and ph responsive micellar nanoparticles for anticancer drug delivery
Nanomedicine: Nanotechnology Biology and Medicine, 2018Co-Authors: Jiayu Leong, Willy Chin, James L Hedrick, Shujun Gao, Hyunjoon Kong, Yi Yan YangAbstract:Abstract Herein, we report reactive oxygen species (ROS)- and pH-responsive biodegradable polyethylene glycol (PEG)-block-polycarbonate by installing thioether groups onto the polycarbonate and its self-assembled core/shell structured micelles for anticancer drug delivery. Oxidation of thioethers to sulfoxide and subsequently sulfone induces an increase in hydrophilicity, resulting in more hydrophilic micellar core. This phase-change caused the micelles to swell and enhance cargo release. Carboxylic acid groups have also been installed onto thioether-containing polycarbonate to promote loading of amine-containing anticancer doxorubicin through electrostatic interaction. Urea-functionalized thioether-containing PEG-block-Polycarbonates were synthesized to mix with the acid-functionalized PEG-block-polycarbonate for stabilizing micelle structure through hydrogen-bonding interaction. The mixed micelles were 50 nm in diameter and had a 25 wt% loading capacity for doxorubicin. Enhanced drug release from the micelles was triggered by low pH and high content of ROS. Drug-encapsulated micelles accumulated in tumors through leaky tumor vasculature in PC-3 human prostate cancer xenograft mouse model.
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benzyl chloride functionalized Polycarbonates a versatile platform for the synthesis of functional biodegradable Polycarbonates
Macromolecules, 2014Co-Authors: Shrinivas Venkataraman, Willy Chin, Yi Yan Yang, James L HedrickAbstract:An aliphatic polycarbonate containing pendant benzyl chloride groups was synthesized by organocatalytic ring-opening polymerization (ROP) of a cyclic carbonate monomer (MTC–OCH2BnCl). Facile postpolymerization modification of the resultant polymer with various nucleophiles facilitated access to a functionally diverse variety of polycarbonate materials in high yield, including those that contained diethanolamine, phosphonium, and azide groups. The azide-functionalized Polycarbonates could be further elaborated via Cu-catalyzed click chemistry with alkynyl-functionalized poly(ethylene glycol) (PEG) or pyrene to form the corresponding PEG- or pyrene-grafted polymers. Finally, an amphiphilic block copolymer containing grafted pyrene units in the hydrophobic block was synthesized using the aforementioned postpolymerization click functionalization strategy. We show by transmission electron microscopy (TEM) and light scattering that the block copolymer self-assembles into micelles of ∼48 nm diameter in aqueous m...
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Biodegradable Broad-Spectrum Antimicrobial Polycarbonates: Investigating the Role of Chemical Structure on Activity and Selectivity
Macromolecules, 2013Co-Authors: Willy Chin, James L Hedrick, Daniel J Coady, Chuan Yang, Yuan Huang, Junchi Cheng, Yen Wah Tong, Weimin Fan, Yi Yan YangAbstract:A series of biodegradable polycarbonate polymers was designed and synthesized via organocatalytic ring-opening polymerization of functional cyclic carbonate monomer (MTC–OCH2BnCl). By adopting a facile postpolymerization functionalization strategy, the Polycarbonates were quaternized to yield cationic polymers with quaternary ammonium groups of various pendant structures (e.g., alkyl, aromatic, imidazolinium). The biological properties of these polymers were investigated by microbial growth inhibition assays against clinically relevant Gram-positive and Gram-negative bacteria, fungus as well as hemolysis assays using rat red blood cells. A judicious choice in the structure of the cationic appendages elucidated that the amphiphilic balance of the polymers is a pertinent determinant to render substantial antimicrobial potency and low hemolysis, consequently affording the polymer pButyl_20 (degree of polymerization, 20; quaternary ammonium group, N,N-dimethylbutylammonium) as a highly efficacious and nonhemo...
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rational design of biodegradable cationic Polycarbonates for gene delivery
Journal of Controlled Release, 2011Co-Authors: Zhan Yuin Ong, Yi Yan Yang, Kazuki Fukushima, Daniel J Coady, James L HedrickAbstract:Polycarbonates provide an attractive option for use as gene delivery vectors owing to their biocompatibility and ease of incorporating functional moieties. In this study, we described an approach to synthesize cationic polymers with well-defined molecular weights and narrow polydispersities by an organocatalytic ring-opening polymerization of functional cyclic carbonates containing alkyl halide side chains, followed by a subsequent functionalization step with bis-tertiary amines designed to facilitate gene binding and endosomal escape. The cationic polycarbonate effectively condensed DNA at low N/P ratios, generating nanoparticles (83 to 124 nm in diameter) with positive zeta potentials (~27 mV). In addition, reporter gene expression efficiencies in HepG2, HEK293, MCF-7 and 4T1 cell lines were high even in the presence of serum. Importantly, the polycarbonate delivery agent demonstrated minimal cytotoxicity at the optimal N/P ratios determined to confer high gene expression efficiencies. Therefore, this biodegradable polymer is presented as a promising non-viral vector for gene delivery.