Yulia Lumelsky

Bio: Yulia Lumelsky is an academic researcher from Technion – Israel Institute of Technology. The author has contributed to research in topics: Polycaprolactone & Barium nitrate. The author has an hindex of 8, co-authored 9 publications receiving 408 citations.

Porous Polycaprolactone-Polystyrene Semi-interpenetrating Polymer Networks Synthesized within High Internal Phase Emulsions

Abstract: PolyHIPE are highly porous, open-pore, cross-linked polymers synthesized within high internal phase emulsions (HIPE). Biodegradable polycaprolactone (PCL) oligomers were incorporated into polyHIPE using two approaches. The first approach involved copolymerization with a vinyl-terminated PCL (PCL-VL). This approach yielded a typical polyHIPE structure with voids on the order of tens of microns. The covalent bonds formed by PCL-VL prevented its removal during emulsifier extraction. The second approach involved the formation of semi-interpenetrating polymer networks (semi-IPN) with a PCL diol (PCL-OL). The relatively hydrophilic PCL-OL destabilized the HIPE and produced voids on the order of hundreds of microns, a size more appropriate for tissue engineering applications. The PCL-OL, which is more mobile than the covalently bound PCL-VL, underwent more extensive phase separation. In addition, a significant amount of PCL-OL was removed during emulsifier extraction. Cells were successfully attached to the surface of a semi-IPN polyHIPE, forming a monolayer. Eventually, spontaneous differentiation of the cells and the formation of myotubes were observed.

Biodegradable Porous Polymers through Emulsion Templating

Abstract: Highly porous, emulsion-templated polymers, polyHIPE, that are synthesized within high internal phase emulsions (HIPE) combine a fully interconnected open-pore structure with mechanical integrity and the ability to absorb relatively large amounts of liquid through capillary action. Biodegradable polyHIPE would be of interest for tissue engineering scaffold applications. This paper describes the synthesis of both styrene-based and acrylate-based polyHIPE containing as much as 50 wt % of a biodegradable polycaprolactone (PCL) oligomer. The addition of PCL destabilizes the HIPE, yielding a partial collapse of the porous structure. This collapse yields a decrease in the relative mass of water absorbed, although the volumetric ratio of water absorbed to pore volume increases. The relatively low modulus, acrylate-based polyHIPE with 50% PCL underwent swelling, absorbing more than twice its pore volume. This polyHIPE also underwent extensive degradation, indicating that the PCL degradation promotes the disintegr...

A degradable, porous, emulsion‐templated polyacrylate

Abstract: A polyHIPE is a highly porous, emulsion-templated polymer synthesized by polymerizing a monomer and a crosslinking comonomer in the continuous phase of a high-internal phase emulsion (HIPE). The synthesis of degradable polyHIPE could be of interest for biomedical applications such as tissue engineering scaffolds. In this research, a poly(e-caprolactone) (PCL) oligomer with terminal vinyl groups was used as the crosslinking comonomer for a polyHIPE based on t-butyl acrylate (tBA). The porous structure, properties, water absorption, and hydrolytic degradation of the polyHIPE were investigated. The polyHIPE containing 50 wt % PCL exhibited very large voids, 1 to 3 mm in diameter that resulted from the destabilization of the HIPE on addition of PCL, making the polyHIPE more suitable for tissue engineering applications. The relatively flexible PCL enhanced segmental mobility, yielding two glass transition temperatures and a significant reduction in modulus. When exposed to a 3 M aqueous solution of NaOH, the t-butyl groups underwent hydrolysis and the PCL underwent degradation, rapidly leading to the complete disintegration of the macromolecular structure. The tBA-based polyHIPE containing 50 wt % PCL exhibited enhanced cell adhesion, penetration, and growth indicating that it is a suitable candidate for further research and development. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2009

Design and Preparation of Porous Polymers

Abstract: Dingcai Wu,*,† Fei Xu,† Bin Sun,† Ruowen Fu,† Hongkun He,‡ and Krzysztof Matyjaszewski*,‡ †Materials Science Institute, Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275, People's Republic of China ‡Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States

Gas Sensors Based on Conducting Polymers

Abstract: The gas sensors fabricated by using conducting polymers such as polyaniline (PAni), polypyrrole (PPy) and poly (3,4-ethylenedioxythiophene) (PEDOT) as the active layers have been reviewed. This review discusses the sensing mechanism and configurations of the sensors. The factors that affect the performances of the gas sensors are also addressed. The disadvantages of the sensors and a brief prospect in this research field are discussed at the end of the review.

Hierarchically porous materials: synthesis strategies and structure design

Abstract: Owing to their immense potential in energy conversion and storage, catalysis, photocatalysis, adsorption, separation and life science applications, significant interest has been devoted to the design and synthesis of hierarchically porous materials. The hierarchy of materials on porosity, structural, morphological, and component levels is key for high performance in all kinds of applications. Synthesis and applications of hierarchically structured porous materials have become a rapidly evolving field of current interest. A large series of synthesis methods have been developed. This review addresses recent advances made in studies of this topic. After identifying the advantages and problems of natural hierarchically porous materials, synthetic hierarchically porous materials are presented. The synthesis strategies used to prepare hierarchically porous materials are first introduced and the features of synthesis and the resulting structures are presented using a series of examples. These involve templating methods (surfactant templating, nanocasting, macroporous polymer templating, colloidal crystal templating and bioinspired process, i.e. biotemplating), conventional techniques (supercritical fluids, emulsion, freeze-drying, breath figures, selective leaching, phase separation, zeolitization process, and replication) and basic methods (sol–gel controlling and post-treatment), as well as self-formation phenomenon of porous hierarchy. A series of detailed examples are given to show methods for the synthesis of hierarchically porous structures with various chemical compositions (dual porosities: micro–micropores, micro–mesopores, micro–macropores, meso–mesopores, meso–macropores, multiple porosities: micro–meso–macropores and meso–meso–macropores). We hope that this review will be helpful for those entering the field and also for those in the field who want quick access to helpful reference information about the synthesis of new hierarchically porous materials and methods to control their structure and morphology.

Scaffold: A Novel Carrier for Cell and Drug Delivery

Abstract: Scaffolds are implants or injects, which are used to deliver cells, drugs, and genes into the body. Different forms of polymeric scaffolds for cell/drug delivery are available: (1) a typical three-dimensional porous matrix, (2) a nanofibrous matrix, (3) a thermosensitive sol-gel transition hydrogel, and (4) a porous microsphere. A scaffold provides a suitable substrate for cell attachment, cell proliferation, differentiated function, and cell migration. Scaffold matrices can be used to achieve drug delivery with high loading and efficiency to specific sites. Biomaterials used for fabrication of scaffold may be natural polymers such as alginate, proteins, collagens, gelatin, fibrins, and albumin, or synthetic polymers such as polyvinyl alcohol and polyglycolide. Bioceramics such as hydroxyapatites and tricalcium phosphates also are used. Techniques used for fabrication of a scaffold include particulate leaching, freeze-drying, supercritical fluid technology, thermally induced phase separation, rapid prototyping, powder compaction, sol-gel, and melt moulding. These techniques allow the preparation of porous structures with regular porosity. Scaffold are used successfully in various fields of tissue engineering such as bone formation, periodontal regeneration, repair of nasal and auricular malformations, cartilage development, as artificial corneas, as heart valves, in tendon repair ,in ligament replacement, and in tumors. They also are used in joint pain inflammation, diabetes, heart disease, osteochondrogenesis, and wound dressings. Their application of late has extended to delivery of drugs and genetic materials, including plasmid DNA, at a controlled rate over a long period of time. In addition, the incorporation of drugs (i.e., inflammatory inhibitors and/or antibiotics) into scaffolds may be used to prevent infection after surgery and other disease for longer duration. Scaffold also can be used to provide adequate signals (e.g., through the use of adhesion peptides and growth factors) to the cells, to induce and maintain them in their desired differentiation stage, and to maintain their survival and growth. The present review gives a detailed account of the need for the development of scaffolds along with the materials used and techniques adopted to manufacture scaffolds for tissue engineering and for prolonged drug delivery.