The Experts below are selected from a list of 3807 Experts worldwide ranked by ideXlab platform
Yusuf Yagci - One of the best experts on this subject based on the ideXlab platform.
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visible light induced conventional Step Growth and chain Growth condensation Polymerizations by electrophilic aromatic substitution
Macromolecular Rapid Communications, 2021Co-Authors: Huseyin Cem Kiliclar, Yusuf Yagci, Emirhan GencosmanAbstract:A novel visible light induced Step-Growth Polymerization by electrophilic aromatic substitution between photochemically generated carbocations and dimethoxybenzene nucleophile is described. Conventional Step-Growth Polymerization and chain-Growth condensation Polymerization (CCP) mechanisms are presented. It was found that by changing the molar ratios of the monomers slightly, the CCP mechanism becomes operative and relatively higher molecular weight polymers were obtained because of the higher reactivity of the end groups of the intermediates and oligomers than that of the monomers. The possibility of grafting onto polymers containing epoxide at their side chains by photoinduced chain end activation of poly(dimethoxyphenylene methylene) is demonstrated. This study is expected to promote potential applications of the combination of photoinduced electron transfer reactions and CCP in macromolecular synthesis and material science. This article is protected by copyright. All rights reserved.
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visible light induced Step Growth Polymerization by electrophilic aromatic substitution reactions
Chemical Communications, 2021Co-Authors: Huseyin Cem Kiliclar, Cagatay Altinkok, Gorkem Yilmaz, Yusuf YagciAbstract:A novel visible light induced Step-Growth Polymerization to form poly(phenylene methylene) by electrophilic aromatic substitution reactions is described. The effect of different nucleophilic aromatic molecules on Polymerization has been investigated. The possibility of combining Step-Growth Polymerization with conventional free radical and free radical promoted cationic Polymerizations through photoinduced chain-end activation has been demonstrated. Highly fluorescent fibers of the resulting block copolymers were obtained using the electrospinning technique. The versatile photoinduced Step-Growth Polymerization process reported herein paves the way for a new generation of polycondensates and their combination with chain polymers that cannot be obtained by conventional methods.
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photoinitiated Polymerization advances challenges and opportunities
Macromolecules, 2010Co-Authors: Yusuf Yagci, Steffen Jockusch, Nicholas J TurroAbstract:The use of photoinitiated Polymerization is continuously growing in industry as reflected by the large number of applications in not only conventional areas such as coatings, inks, and adhesives but also high-tech domains, optoelectronics, laser imaging, stereolithography, and nanotechnology. In this Perspective, the latest developments in photoinitiating systems for free radical and cationic Polymerizations are presented. The potential use of photochemical methods for Step-Growth Polymerization is also highlighted. The goal is, furthermore, to show approaches to overcome problems associated with the efficiency, wavelength flexibility, and environmental and safety issues in all photoinitiating systems for different modes of activation. Much progress has been made in the past 10 years in the preparation of complex and nano-structured macromolecules by using photoinitiated Polymerizations. Thus, the new and emerging applications of photoinitiated Polymerizations in the field of biomaterials, surface modific...
Ke Zhang - One of the best experts on this subject based on the ideXlab platform.
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stoichiometric imbalance promoted Step Growth Polymerization based on self accelerating 1 3 dipolar cycloaddition click reactions
Polymer Chemistry, 2020Co-Authors: Lue Xiang, Jiayi Li, Ying Wu, Ke ZhangAbstract:A library of self-accelerating click reactions was developed based on the 1,3-dipolar cycloaddition of sym-dibenzo-1,5-cyclooctadiene-3,7-diyne (DIBOD) and varied 1,3-dipoles, such as diazo, sydnone, and nitrone groups. A common feature of these reactions was that the reaction of a 1,3-dipole and the first alkyne moiety of DIBOD activated in situ the second alkyne moiety, which consequently reacted with a 1,3-dipole at a much faster rate than did the original DIBOD alkyne group. Because these were Polymerization reactions, a novel kind of stoichiometric imbalance-promoted Step-Growth Polymerization method was developed specifically to prepare high molecular weight (>105 g mol−1) polymers containing five-membered heterocycles inside polymer backbones. The self-accelerating property of the DIBOD-based 1,3-dipolar cycloadditions enabled the use of Step-Growth Polymerization to prepare high molecular weight polymers under stoichiometric imbalance conditions using an excess of DIBOD over bis-dipole monomers. The click characteristics of the DIBOD-based 1,3-dipolar cycloadditions assisted the Step-Growth Polymerization so that polymers could be prepared under ambient and catalyst-free conditions. In addition, the varied five-membered heterocycle structures inside the backbones endowed the resultant polymers with distinctly unique properties and functions. The polymers with isoxazoline groups inside the backbones demonstrated self-degradation behavior, where higher molecular weights resulted in greater degradation. The polymers with pyrazole groups inside the backbones had excellent thermal properties: the decomposition temperature at 5% weight loss could reach 576 °C, the glass transition temperature could not be measured up to 400 °C, and the char yield at 800 °C was as high as 71%.
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Step Growth Polymerization method for ultrahigh molecular weight polymers
ACS Macro Letters, 2019Co-Authors: Liangcai Zhang, Xiangzhu Ren, Yuanxing Zhang, Ke ZhangAbstract:The preparation of polymers with an ultrahigh molecular weight (>106 g/mol; UHMW) is always a challenge for homogeneous Step-Growth Polymerization. Herein, a unique homogeneous Step-Growth Polymerization method was developed to prepare various UHMW polymers. In this approach, a double-strain-promoted azide–alkyne click reaction (DSPAAC) with a reactive intermediate was used as the Polymerization reaction, and sym-dibenzo-1,5-cyclooctadiene-3,7-diyne (DIBOD) and bis-azide compounds with 2,6-diisopropylphenyl azide terminals were used as the monomer pairs. The DSPAAC reaction, with a reactive intermediate, facilitated this Polymerization method to efficiently prepare UHMW polymers under convenient, stoichiometrically imbalanced conditions using a slight excess of DIBOD to bis-azide monomer. In addition, the click nature of the DSPAAC reaction facilitated this Polymerization method to synthesize UHMW polymers under ambient conditions, requiring no catalysts. The resultant UHMW polymers presented strong fluor...
Jasper Van Hoorick - One of the best experts on this subject based on the ideXlab platform.
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photo crosslinkable gelatin derivatives for biofabrication applications
Acta Biomaterialia, 2019Co-Authors: Aleksandr Ovsianikov, Jasper Van Hoorick, Liesbeth Tytgat, Agnes Dobos, Heidi Ottevaere, Jurgen Van Erps, Hugo Thienpont, Peter DubruelAbstract:Abstract Over the recent decades gelatin has proven to be very suitable as an extracellular matrix mimic for biofabrication and tissue engineering applications. However, gelatin is prone to dissolution at typical cell culture conditions and is therefore often chemically modified to introduce (photo-)crosslinkable functionalities. These modifications allow to tune the material properties of gelatin, making it suitable for a wide range of biofabrication techniques both as a bioink and as a biomaterial ink (component). The present review provides a non-exhaustive overview of the different reported gelatin modification strategies to yield crosslinkable materials that can be used to form hydrogels suitable for biofabrication applications. The different crosslinking chemistries are discussed and classified according to their mechanism including chain-Growth and Step-Growth Polymerization. The Step-Growth Polymerization mechanisms are further classified based on the specific chemistry including different (photo-)click chemistries and reversible systems. The benefits and drawbacks of each chemistry are also briefly discussed. Furthermore, focus is placed on different biofabrication strategies using either inkjet, deposition or light-based additive manufacturing techniques, and the applications of the obtained 3D constructs. Statement of Significance Gelatin and more specifically gelatin-methacryloyl has emerged to become one of the gold standard materials as an extracellular matrix mimic in the field of biofabrication. However, also other modification strategies have been elaborated to take advantage of a plethora of crosslinking chemistries. Therefore, a review paper focusing on the different modification strategies and processing of gelatin is presented. Particular attention is paid to the underlying chemistry along with the benefits and drawbacks of each type of crosslinking chemistry. The different strategies were classified based on their basic crosslinking mechanism including chain- or Step-Growth Polymerization. Within the Step-Growth classification, a further distinction is made between click chemistries as well as other strategies. The influence of these modifications on the physical gelation and processing conditions including mechanical properties is presented. Additionally, substantial attention is put to the applied photoinitiators and the different biofabrication technologies including inkjet, deposition or light-based technologies.
Huseyin Cem Kiliclar - One of the best experts on this subject based on the ideXlab platform.
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visible light induced conventional Step Growth and chain Growth condensation Polymerizations by electrophilic aromatic substitution
Macromolecular Rapid Communications, 2021Co-Authors: Huseyin Cem Kiliclar, Yusuf Yagci, Emirhan GencosmanAbstract:A novel visible light induced Step-Growth Polymerization by electrophilic aromatic substitution between photochemically generated carbocations and dimethoxybenzene nucleophile is described. Conventional Step-Growth Polymerization and chain-Growth condensation Polymerization (CCP) mechanisms are presented. It was found that by changing the molar ratios of the monomers slightly, the CCP mechanism becomes operative and relatively higher molecular weight polymers were obtained because of the higher reactivity of the end groups of the intermediates and oligomers than that of the monomers. The possibility of grafting onto polymers containing epoxide at their side chains by photoinduced chain end activation of poly(dimethoxyphenylene methylene) is demonstrated. This study is expected to promote potential applications of the combination of photoinduced electron transfer reactions and CCP in macromolecular synthesis and material science. This article is protected by copyright. All rights reserved.
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visible light induced Step Growth Polymerization by electrophilic aromatic substitution reactions
Chemical Communications, 2021Co-Authors: Huseyin Cem Kiliclar, Cagatay Altinkok, Gorkem Yilmaz, Yusuf YagciAbstract:A novel visible light induced Step-Growth Polymerization to form poly(phenylene methylene) by electrophilic aromatic substitution reactions is described. The effect of different nucleophilic aromatic molecules on Polymerization has been investigated. The possibility of combining Step-Growth Polymerization with conventional free radical and free radical promoted cationic Polymerizations through photoinduced chain-end activation has been demonstrated. Highly fluorescent fibers of the resulting block copolymers were obtained using the electrospinning technique. The versatile photoinduced Step-Growth Polymerization process reported herein paves the way for a new generation of polycondensates and their combination with chain polymers that cannot be obtained by conventional methods.
Peter Dubruel - One of the best experts on this subject based on the ideXlab platform.
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photo crosslinkable gelatin derivatives for biofabrication applications
Acta Biomaterialia, 2019Co-Authors: Aleksandr Ovsianikov, Jasper Van Hoorick, Liesbeth Tytgat, Agnes Dobos, Heidi Ottevaere, Jurgen Van Erps, Hugo Thienpont, Peter DubruelAbstract:Abstract Over the recent decades gelatin has proven to be very suitable as an extracellular matrix mimic for biofabrication and tissue engineering applications. However, gelatin is prone to dissolution at typical cell culture conditions and is therefore often chemically modified to introduce (photo-)crosslinkable functionalities. These modifications allow to tune the material properties of gelatin, making it suitable for a wide range of biofabrication techniques both as a bioink and as a biomaterial ink (component). The present review provides a non-exhaustive overview of the different reported gelatin modification strategies to yield crosslinkable materials that can be used to form hydrogels suitable for biofabrication applications. The different crosslinking chemistries are discussed and classified according to their mechanism including chain-Growth and Step-Growth Polymerization. The Step-Growth Polymerization mechanisms are further classified based on the specific chemistry including different (photo-)click chemistries and reversible systems. The benefits and drawbacks of each chemistry are also briefly discussed. Furthermore, focus is placed on different biofabrication strategies using either inkjet, deposition or light-based additive manufacturing techniques, and the applications of the obtained 3D constructs. Statement of Significance Gelatin and more specifically gelatin-methacryloyl has emerged to become one of the gold standard materials as an extracellular matrix mimic in the field of biofabrication. However, also other modification strategies have been elaborated to take advantage of a plethora of crosslinking chemistries. Therefore, a review paper focusing on the different modification strategies and processing of gelatin is presented. Particular attention is paid to the underlying chemistry along with the benefits and drawbacks of each type of crosslinking chemistry. The different strategies were classified based on their basic crosslinking mechanism including chain- or Step-Growth Polymerization. Within the Step-Growth classification, a further distinction is made between click chemistries as well as other strategies. The influence of these modifications on the physical gelation and processing conditions including mechanical properties is presented. Additionally, substantial attention is put to the applied photoinitiators and the different biofabrication technologies including inkjet, deposition or light-based technologies.