The Experts below are selected from a list of 74079 Experts worldwide ranked by ideXlab platform
Han Mo Jeong - One of the best experts on this subject based on the ideXlab platform.
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Nylon 6-polyethersulfone-nylon 6 Block Copolymer: synthesis and application as compatibilizer for polyethersulfone/nylon 6 blend
Polymer, 1998Co-Authors: Sung Chul Hong, Han Mo JeongAbstract:Abstract Nylon 6-polyethersulfone (PES)-nylon 6 Block Copolymers were synthesized by anionic polymerization of ϵ-caprolactam using chlorine-terminated PES, a polymeric activator. The structure and properties of these Block polymers were examined using infra-red, nuclear magnetic resonance, differential scanning calorimetry, transmission electron microscopy, and thermogravimetric analysis. The compatibilizing effects of this Block Copolymer on PES/nylon 6 blends were investigated by examining thermal properties, morphology and dynamic mechanical characteristics. When the Block Copolymer was added, the size of dispersed phase in the blend decreased dramatically, and the glass transition temperatures of the constituent polymers converge. The improvement of dynamic tensile modulus and thermal resistance due to the dispersed PES phase were enhanced by the added Block Copolymer.
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Compatibilizing effect of polyarylate‐polystyrene Block Copolymer in polyarylate/polystyrene blends
Journal of Polymer Science Part B, 1994Co-Authors: Han Mo Jeong, Lee Soon ParkAbstract:The compatibilizing effect of polyarylate-polystyrene (PAR-PS) Block Copolymer prepared from macroazo initiator was examined in polyarylate/polystyrene blends from the view-points of morphology, density, and thermal, mechanical, and rheological properties. PARPS Block Copolymer enhanced the mutual dissolution of the homopolymers. Reduced dispersed-domain size and increased density showed the efficiency of the Block Copolymer as a compatibilizing agent. Results from mechanical and rheological properties could also be explained by the compatibilizing effect of PAR-PS Block Copolymer in the blends. © 1994 John Wiley & Sons, Inc.
Yue Zhao - One of the best experts on this subject based on the ideXlab platform.
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photo responsive Block Copolymer micelles design and behavior
Chemical Society Reviews, 2013Co-Authors: Jean-françois Gohy, Yue ZhaoAbstract:Stimuli-responsive Block Copolymer micelles are the topic of intense research since they are able to show sharp and eventually reversible responses to various environmental changes and find applications in various fields including controlled drug delivery. Among all the available stimuli, light has recently attracted much attention since it can be localized in time and space, and it can also be triggered from outside of the system. In this tutorial review, we highlight the progress realized in recent years. More precisely, we provide some guidelines towards the rational design of photo-responsive Block Copolymers and we present the different photo-responsive moieties that have been used so far. We also discuss the different types of irreversible and reversible responses encountered by photo-responsive Block Copolymer micelles. Finally, we suggest possible future developments including the design of biocompatible systems operating at excitation wavelengths compatible for biomedical applications.
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light responsive Block Copolymer micelles
Macromolecules, 2012Co-Authors: Yue ZhaoAbstract:The association state of light-responsive Block Copolymer (BCP) micelles in aqueous solution can be altered, often reversibly, by light. Driven by the potential application in controlled drug delivery, this type of stimuli-responsive polymer micelles has received increasing attention. This Perspective highlights the progress achieved in recent years. On the one hand, we discuss the different approaches of rational BCP design, making use of various photochromic moieties and photochemical reactions, and the underlying mechanisms leading to photoinduced disruption of BCP micelles. On the other hand, we suggest possible future directions in this area, including exploration of new mechanisms and chemistry and solutions to the excitation wavelength problem crucial for biomedical applications.
Doo Sung Lee - One of the best experts on this subject based on the ideXlab platform.
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in situ gelling ph and temperature sensitive biodegradable Block Copolymer hydrogels for drug delivery
Journal of Controlled Release, 2014Co-Authors: Narendra K Singh, Doo Sung LeeAbstract:Stimuli-sensitive injectable polymeric hydrogels have been extensively investigated during the past decade as bioactive agent delivery vehicles and for tissue engineering applications. An aqueous solution of these polymers undergoes a sol-to-gel phase transition in response to external stimuli such as pH, temperature, salt, light, biomolecules, electromagnetic field, etc. Bioactive molecules or cells can be mixed into the low-viscosity state of the polymer solution and injected into the body at a target site, forming an in situ hydrogel depot, which can then serve as bioactive-molecule-releasing carriers or a cell-growing microenvironment. This review systematically summarizes the recent progress in biodegradable and injectable Block Copolymer hydrogels, giving special attention to the novel and promising pH- and temperature-sensitive injectable Block Copolymer hydrogels for biomedical applications. The gelation mechanism, formation of ionic complexes, and biodegradation are highlighted as key factors responsible for controlled protein/drug delivery. The advantages and perspectives of pH- and temperature-sensitive injectable Block Copolymer hydrogels are also highlighted.
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in situ gelling stimuli sensitive Block Copolymer hydrogels for drug delivery
Journal of Controlled Release, 2008Co-Authors: Sung Wan Kim, Doo Sung LeeAbstract:Stimuli-sensitive Block Copolymer hydrogels, which are reversible polymer networks formed by physical interactions and exhibit a sol-gel phase-transition in response to external stimuli, have great potential in biomedical and pharmaceutical applications, especially in site-specific controlled drug-delivery systems. The drug may be mixed with a polymer solution in vitro and the drug-loaded hydrogel can form in situ after the in vivo administration, such as injection; therefore, stimuli-sensitive Block Copolymer hydrogels have many advantages, such as simple drug formulation and administration procedures, no organic solvent, site-specificity, a sustained drug release behavior, less systemic toxicity and ability to deliver both hydrophilic and hydrophobic drugs. Among the stimuli in the biomedical applications, temperature and pH are the most popular physical and chemical stimuli, respectively. The temperature- and/or pH-sensitive Block Copolymer hydrogels for biomedical applications have been extensively developed in the past decade. This review focuses on recent development of the preparation and application for drug delivery of the Block Copolymer hydrogels that respond to temperature, pH or both stimuli, including poly(N-substituted acrylamide)-based Block Copolymers, poloxamers and their derivatives, poly(ethylene glycol)-polyester Block Copolymers, polyelectrolyte-based Block Copolymers and the polyelectrolyte-modified thermo-sensitive Block Copolymers. In addition, the hydrogels based on other stimuli-sensitive Block Copolymers are discussed.
Sung Chul Hong - One of the best experts on this subject based on the ideXlab platform.
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Nylon 6-polyethersulfone-nylon 6 Block Copolymer: synthesis and application as compatibilizer for polyethersulfone/nylon 6 blend
Polymer, 1998Co-Authors: Sung Chul Hong, Han Mo JeongAbstract:Abstract Nylon 6-polyethersulfone (PES)-nylon 6 Block Copolymers were synthesized by anionic polymerization of ϵ-caprolactam using chlorine-terminated PES, a polymeric activator. The structure and properties of these Block polymers were examined using infra-red, nuclear magnetic resonance, differential scanning calorimetry, transmission electron microscopy, and thermogravimetric analysis. The compatibilizing effects of this Block Copolymer on PES/nylon 6 blends were investigated by examining thermal properties, morphology and dynamic mechanical characteristics. When the Block Copolymer was added, the size of dispersed phase in the blend decreased dramatically, and the glass transition temperatures of the constituent polymers converge. The improvement of dynamic tensile modulus and thermal resistance due to the dispersed PES phase were enhanced by the added Block Copolymer.
Redouane Borsali - One of the best experts on this subject based on the ideXlab platform.
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Nano-Organization of Amylose-b-Polystyrene Block Copolymer Films Doped with Bipyridine
Langmuir, 2011Co-Authors: Karim Aissou, Issei Otsuka, Cyrille Rochas, Sébastien Fort, Sami Halila, Redouane BorsaliAbstract:This paper discusses the self-assembly of rod-coil amylose-b-polystyrene (Mal-b-PS) Block Copolymer thick and thin films. The nano-organization falls in an interdomain spacing d of about 10 am, much smaller than flexible-flexible petrol Block Copolymer systems. Additionally, hydrogen-bonding interactions between carbohydrate rods (amylose) and 4',4-bipyridine (bipy) molecules induces phase transitions. Indeed, adding bipy in maltooctadecaose-Block-polystyrene (Mal18-b-PS) Copolymers results, at room temperature, in the formation of a lamellar phase having Mal18 bipy-rich nanodomains instead of hexagonal close-packed (HCP) of cylinders made of Mal18, whereas a coexistence of Mal7bipy-rich cylindrical and spherical nanodomains are formed from maltoheptaose-b-polystyrene (Mal7-b-PS) Copolymers instead of a poorly organized array of Mal7-based cylinders. On heating, the Mal7bipy-b-PS system shows more rich phase behavior as compared to the Mal7-b-PS one due to weakening of hydrogen bonding with temperature. Such a system is of great interest in developing active layers in light-emitting diodes (LEDs) or in photovoltaic cells to realize devices with an optimal structure, that is, having large interface area and domain size with similar exciton diffusion length (10 nm).
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Block Copolymer systems: From single chain to self-assembled nanostructures
Langmuir, 2010Co-Authors: Cristiano Giacomelli, Vanessa Schmidt, Karim Aissou, Redouane BorsaliAbstract:Recent advances in the field of macromolecular engineering applied to the fabrication of nanostructured materials using Block Copolymer chains as elementary building Blocks are described in this feature article. By highlighting some of our work in the area and accounting for the contribution of other groups, we discuss the relationship between the physical-chemical properties of Copolymer chains and the characteristics of nano-objects originating from their self-assembly in solution and in bulk, with emphasis on convenient strategies that allow for the control of composition, functionality, and topology at different levels of sophistication. In the case of micellar nanoparticles in solution, in particular, we present approaches leading to morphology selection via macromolecular architectural design, the functionalization of external solvent-philic shells with biomolecules (polysaccharides and proteins), and the maximization of micelle loading capacity by the suitable choice of solvent-phobic polymer segments. The fabrication of nanomaterials mediated by thin Block Copolymer films is also discussed. In this case, we emphasize the development of novel polymer chain manipulation strategies that ultimately allow for the preparation of precisely positioned nanodomains with a reduced number of defects via Block-selective chemical reactivity. The challenges facing the soft matter community, the urgent demand to convert huge public and private investments into consumer products, and future possible directions in the field are also considered herein.