A coordination polymer is an inorganic or organometallic polymer structure containing metal cation centers linked by organic ligands. More formally a coordination polymer is a coordination compound with repeating coordination entities extending in 1, 2, or 3 dimensions. It can also be described as a polymer whose repeat units are coordination complexes. Coordination polymers contain the subclass coordination networks that are coordination compounds extending, through repeating coordination entities, in 1 dimension, but with cross-links between two or more individual chains, loops, or spiro-links, or a coordination compound extending through repeating coordination entities in 2 or 3 dimensions. A subclass of these are the metal-organic frameworks, or MOFs, that are coordination networks with organic ligands containing potential voids. Coordination polymers are relevant to many fields such as organic and inorganic chemistry, biochemistry, materials science, electrochemistry, and pharmacology, ...
The fabrication of electronic devices, such as gas sensors on flexible polymer substrates, enables the use of electronics in applications where conventional devices on stiff substrates could not be used. We demonstrate the development of a new intra-tube electronic-nose (e-nose) gas sensor device with multiple sensors fabricated and integrated on a flexible substrate. For this purpose, we developed a new method of fabricating a sensor array of four gas sensors on a flexible polymer substrate. The method allowed the use of lithography techniques to pattern different polymers with a broad range of solubility parameters. Conductive polymer composites were used as a gas sensitive layer due to the high stretchability of the material. Each of the 30 e-nose devices on one substrate was designed to fit on a polymer strip with a width of 2 mm. A single e-nose strip was successfully integrated into the inlet tube of a gas-measurement apparatus with an inner-tube diameter of 3 mm. Using the e-nose, we were able to
A polarizer is formed with an arrangement of polymer fibers substantially parallel within a polymer matrix. The polymer fibers are formed of at least first and second polymer materials. At least one of the polymer matrix and the first and second polymer materials is birefringent, and provides a birefringent interface with the adjacent material. Light is reflected and/or scattered at the birefringent interfaces with sensitivity to the polarization of the light. In some embodiments, the polymer fibers are formed as composite fibers, having a plurality of scattering polymer fibers disposed within a filler to form the composite fiber. In other embodiments, the polymer fiber is a multilayered polymer fiber. The polymer fibers may be arranged within the polymer matrix as part of a fiber weave.
The present invention concerns blends comprising at least one shape memory polymer and at least one thermoplastic polymer, wherein this thermoplastic polymer does not show shape memory properties. The present invention furthermore concerns methods for preparing such blends and the use of these blends in various applications, including additional products, household equipment etc.
0063] As indicated above, the shape memory polymer may be a copolymer network including the reaction product of a free radically polymerizable siloxane having greater than one functional free radically polymerizable group and at least one (meth)acrylate monomer. The reaction may include, for example, polymerization via curing. Curing may be carried out in an oxygen-free, e.g., in an inert atmosphere such as nitrogen gas or by utilizing a barrier of radiation-transparent material having low oxygen permeability. Curing can also be carried out under an inerting fluid such as water. When visible or ultraviolet radiation is used for curing, the reaction may also contain a photoinitiator. Suitable photoinitiators include benzoin ethers, benzophenone and derivatives thereof, acetophenone derivatives, camphorquinone, and the like. Some examples of commercially available photoinititaors include DARACUR 1173, DAROCUR 4265, IRGACURE 651, IRGACURE 1800, IRGACURE 369, IRGACURE 1700, and IRGACURE 907, ...
Described are fixed and removable orthodontic appliances and components thereof fabricated from shape memory polymer compositions. The preparation and use of such appliances are also disclosed.
Functionalization of nanoparticles can significantly influence their properties and potential applications. Although researchers can now functionalize metal, metal oxide, and organic polymer nanoparticles with a high degree of precision, controlled surface functionalization of nanoscale coordination polymer particles (CPPs) has remained a significant challenge. The lack of methodology is perhaps one of the greatest roadblocks to the advancement of CPPs into high added-value drug delivery applications. Here, we report having achieved this goal through a stepwise formation and functionalization protocol. We fabricated robust nanoparticles with enhanced thermal and colloidal stabilities by incorporation of carboxyl groups and these surface carboxyl groups could be subsequently functionalized through well-known peptide coupling reactions. The set of chemistries that we employed as proof-of-concept enabled a plethora of new functional improvements for the application of CPPs as drug delivery ...
0024] In various embodiments, the components of the dry adhesive or the components of the shape memory polymer may include a rigid epoxy and a flexible epoxy. The range of possible crosslinking chemistries which may be used to achieve a dry adhesive or shape memory polymer may include alpha, omega-diaminoalkanes, organic multi-carboxylic acid, anhydride, or catalytic (as in imidazole type) crosslinking reactions. There are many different ways to achieve the appropriate relationships between the molecular properties. For example, the dry adhesives or shape memory polymers may include a rigid epoxy, an epoxy extender, and a crosslinking agent; or a rigid epoxy, a flexible crosslinking agent, and a flexible epoxy; or a rigid epoxy, a rigid crosslinking agent, and a flexible epoxy; or a rigid epoxy, a flexible epoxy, and a catalytic curing agent; or a rigid epoxy, a crosslinking agent, and a diluent; or a flexible epoxy, a crosslinking agent, and a diluent; or a rigid epoxy and a flexible ...
Long fiber-reinforced polymer structures offer lightweight design potential. However, there is still a need for methods that consider the complex material behavior in the design process. This contribution discusses the integration of the local, anisotropic material properties of long fiber-reinforced polymer structures into the calculation of bead patterns and bead geometries. A workflow to calculate the resulting component stiffness is presented. To this end, mold filling simulations using Moldflow are coupled with a bead calculation process, which uses Abaqus for the structural calculations. This requires a mapping process to provide the results of the mold filling simulation for the bead calculation. As commercial tools do not allow independently modifying the bead parameters height, width, base radius, head radius and flange angle, an algorithm is used to calculate the bead geometry and to generate more degree of design freedom ...
A polymer based circuit production method provides a polymer based circuit by exposing a surface of a polymer substrate to ultraviolet radiation resulting in an adhesion promoted polymer substrate surface. A circuit is fabricated on the polymer substrate surface and a coating material is applied to at least a portion of the adhesion promoted polymer substrate surface. A portion of the circuit fabricated on the polymer substrate surface may be encapsulated. The polymer based circuit resulting from the method includes a polymer substrate having an ultraviolet radiation treated surface, a circuit formed on the polymer substrate surface, and a coating material encapsulating at least a portion of the at least one circuit between the polymer substrate and the coating material.
The invention aims at providing polylactic acid compositions having specific thermal characteristics and gas barrier properties; stretched polylactic acid films excellent in surface smoothness, transparency, heat resistance and toughness; and moldings of a polylactic acid composition comprising PLLA and PDLA. Moldings of a polylactic acid composition which is characterized by exhibiting a peak of 30mJ/mg or above in the DSC when cooled at a temperature fall rate of 10 DEG C/min after the exposure to 250 DEG C for 10 min and preferably by exhibiting a peak(1)/peak (2) ratio of 0.5 or below wherein the peak (1)and the peak (2) are peaks observed in a Tm range of 150 to 180 DEG C and in a Tm range of 200 to 240 DEG C respectively in the DSC in the second heating (conducted at a temperature rise rate of 10 DEG C/min from 0 DEG C after the exposure to 250 DEG C for 10 min and the cooling at a rate of 10 DEG C/min); and moldings of a polylactic acid composition as described above which further contains
Inherently conductive polymers (ICPs) are finally about to leap from the laboratory into the commercial world.. Invented in 1977, ICPs have been around for a while, but their true commercial potential has never been realised.. Brian Balmer Industry Analyst at Frost & Sullivan explains, until now, ICPs have been aimed at the traditional conductive polymer markets of electrostatic discharge packaging and anti corrosive coatings. However, they found it difficult to compete on price with existing conductive polymers which are produced by incorporating materials such as carbon black, carbon fibre or fragments of stainless steel into the base polymer. Hence their performance in these markets has been poor. But, new cutting edge technologies such as organic light emitting diodes for flat screen displays, dimmable windows and fuel cells will see sales of ICPs rocket over the next 6 years.. The fastest growth area for the use of conductive polymers is that of Organic Light Emitting Diodes OLEDs, which ...
TY - CONF. T1 - Lithium ion conductive polymer electrolytes by side group rotation(II). AU - Satou, Akira. AU - Nishimura, Shin. AU - Urabe, Syuuichi. AU - Yamamoto, Hitoshi. AU - Ueyama, Norikazu. PY - 2005/12/1. Y1 - 2005/12/1. N2 - In order to improve ionic conductivity of lithium ion conductive polymer at low temperature, novel styrene derivatives (1-4) were synthesized and their ionic conductivities were measured. An ionic conductivity of polymer 1, was above 10-5 S/cm, even at -60°C. Its activation energy below 20°C exhibited 11 kJ/mol. On the other hand, that of poly(ethylene oxide) electrolyte exhibited 105 kJ/mol. The difference of the activation energy implied that lithium ion transfers in polymer electrolytes was promoted by rotation motion of the dimethoxyphenyl side group instead of segmental motion of polymer main chain.. AB - In order to improve ionic conductivity of lithium ion conductive polymer at low temperature, novel styrene derivatives (1-4) were synthesized and their ...
Polymer chemistry, polymer synthesis, polymer physics, polymer physical chemistry, polymer materials, polymer self-assembly, supramolecular polymer, polymer surface interface, polymer nanomaterials, energy polymer materials, biomedical polymer, ecological environment polymer, optoelectronic polymer, polymer processing and high grade Hydrogel, Zhang Xi, macromolecule, macromolecule Journal
The large research effort focused on enhancing nonviral transfection vectors has clearly demonstrated that their macromolecular structure has a significant effect on their transfection efficacy. The 3D branched polymeric structures, such as dendrimers, have proved to be a very effective structure for polymeric transfection vectors; however, so far the dendritic polymers have not delivered on their promise. This is largely because a wide range of dendritic polymer materials with tailored multifunctional properties and biocompatibility required for such applications are not yet accessible by current routes. Herein, we report the design and synthesis of new 3D Single Cyclized polymeric gene vectors with well-defined compositions and functionalities via a one-step synthesis from readily available vinyl monomers. We observe that this polymer structure of a single chain linked to itself interacts differently with plasmid DNA compared to conventional vectors and when tested over a range of cell ...
A variety of water-soluble polymers, when attached to a liposome, substantially increase liposome circulation half-life in animals. However, in certain conditions, liposomes modified with the most widely used polymer, polyethylene glycol (PEG), induce an IgM response resulting in an accelerated blood clearance (ABC) of the liposome upon the second injection. Modification of liposomes with other water-soluble polymers: HPMA (poly[N-(2-hydroxypropyl) methacrylamide]), PVP (poly(vinylpyrrolidone)), PMOX (poly(2-methyl-2-oxazoline)), PDMA (poly(N,N-dimethyl acrylamide)), and PAcM (poly(N-acryloyl morpholine)), increase circulation times of liposomes; but a precise comparison of their ability to promote long circulation or induce the ABC effect has not been reported. To obtain a more nuanced understanding of the role of polymer structure/MW to promote long circulation, we synthesized a library of polymer diacyl chain lipids with low polydispersity (1.04-1.09), similar polymer molecular weights ...
Purpose. Crosslinked, degradable derivatives of low-molecular-weight polyethylenimine (PEI) are relatively efficient and non-cytotoxic gene delivery agents. To further investigate these promising materials, a new synthetic approach was developed using a poly(4-vinylpyridine)-supported Fe(III) catalyst (PVP(Fe(III))) that provides more facile synthesis and enhanced control of polymer molecular weight.. Methods. Biodegradable polymers (D.PEI) comprising 800-Da PEI crosslinked with 1,6-hexanediol diacrylate and exhibiting molecular weights of 1.2, 6.2, and 48 kDa were synthesized utilizing the PVP(Fe(III)) catalyst. D.PEI/DNA polyplexes were characterized using gel retardation, ethidium bromide exclusion, heparan sulfate displacement, and dynamic light scattering. In vitro transfection, cellular uptake, and cytotoxicity of the polyplexes were tested in human cervical cancer cells (HeLa) and human breast cancer cells (MDA-MB-231).. Results. D.PEIs tightly complexed plasmid DNA and formed 320- to ...
When a laboratory is producing vascular stents made from memory polymer, theyll need to have the right selection of methods to deliver a quality product.
Polymers represent the leading and versatile type of biomaterials being extensively applied in biomedical applications such as tissue engineering, nano-medicine, medical devices etc.. The versatility of polymers for biomedical uses is attributed to the relative ease with which polymers can be designed with a range of architecture, functionality and appropriate physical, chemical and biological properties.. Functional polymers are special class of polymers where the polymer chains contain one or more reactive groups attached at the chain end or to the backbone. In biomedical applications, functional polymers are used as building blocks to design complex structures such as nanoparticles, bioconjugation, biocompatible surfaces, scaffolds, hydrogels etc.. ...
Polymers with shape memory properties have been prepared using heparin-inspired segments. The polymers have been prepared as films and foams. Both films and foams demonstrate good shape memory behavior as evidenced by fixity and recovery values. The materials properties of the foams can easily be tuned by va Pioneering Investigators
Cationic polymer/DNA complexes are widely used for gene delivery, although the influence of the cationic polymer on the biophysical properties of the resulting complex is poorly understood. Here, several series of cationic polymers have been used to evaluate the influence of structural parameters on properties of DNA complexes. Parameters studied included the length of side chain, charge type (primary versus tertiary and quaternary), polymer molecular weight, and charge spacing along the polymer backbone. Cationic polymers with short side chains (such as polyvinylamine) formed small complexes, resistant to destabilization by polyanions, with low surface charge, limited transfection activity, and efficient intranuclear transcription. Conversely, cationic polymers with long side chains (e.g., poly[methacryloyl-Gly-Gly-NH-(CH(2))(6)-NH(2))] showed inefficient complex formation, high positive surface charge, and better transfection activity. The effects of molecular weight varied between polymers, for
Synthetic polymers are human-made polymers. From the utility point of view they can be classified into three main categories: thermoplastics, elastomers and synthetic fibers. They are found commonly in a variety of consumer products such as honey, glue, etc. A wide variety of synthetic polymers are available with variations in main chain as well as side chains. The back bones of common synthetic polymers such as polythene, polystyrene and poly acrylates are made up of carbon-carbon bonds, whereas hetero chain polymers such as polyamides, polyesters, polyurethanes, polysulfides and polycarbonates have other elements (e.g. oxygen, sulfur, nitrogen) inserted along to the backbone. Also silicon forms similar materials without the need of carbon atoms, such as silicones through siloxane linkages; these compounds are thus said to be inorganic polymers. Coordination polymers may contain a range of metals in the backbone, with non-covalent bonding present. Some familiar household synthetic polymers ...
To investigate the effect of polymer molecular weight (MW) on rhBMP-2 delivery by thermoreversible polymers, four polymers with similar lower critical solution temperatures (20 degrees -22 degrees C) but different MWs were studied. Thermoreversible polymers were based on N-isopropylacrylamide (NiPAM), ethyl methacrylate (EMA), and N-acryloxysuccinimide (NASI), and had MWs of either approximately 49 kDa or approximately 400 kDa. The NASI content was either 0 or 1-1.6%. High MW polymers, irrespective of their NASI content, formed a stable gel with significantly lower water uptake and exhibited a dense micelle with average pore size smaller than the low MW polymers. NiPAM/EMA polymers without NASI did not conjugate with recombinant human bone morphogenetic protein-2 (rhBMP-2). NiPAM/EMA polymers containing NASI, however, gave conjugation with rhBMP-2. For polymers without NASI, a high MW was essential for rhBMP-2 retention when injected intramuscularly in Sprague-Dawley rats. For NASI-containing polymers,
Preface. List of Contributors.. Polymer Brushes: On the Way to Tailor-Made Surfaces (Jürgen Rühe).. 1 Growth of Polymer Molecules at Surfaces: Introductory Remarks.. 2 Coatings: From First Principles to High-Tech Applications.. 3 Surface-Coating Techniques.. 4 Surface-Attached Polymers.. 5 Polymer Brushes: General Features.. 6 Theory of Polymer Brushes.. 7 Synthesis of Polymer Brushes.. 8 Polymer Brushes as Functional Materials.. 9 Microstructured Polymer Brushes.. 10 Surface-Initiated Polymerization: The Overall Picture.. Part I Synthesis.. 1 Recent Advances in Polymer Brush Synthesis (Anthony M. Granville and William J. Brittain).. 1.1 Introduction.. 1.2 Grafting To Synthesis Technique.. 1.3 Grafting From Synthesis Technique.. 2 Polymer Brushes by Atom Transfer Radical Polymerization (Jeffrey Pyun, Tomasz Kowalewski, and Krzysztof Matyjaszewski).. 2.1 Introduction.. 2.2 Polymer Brushes on Flat Surfaces.. 2.3 Polymer Brushes from Particles.. 2.4 Molecular Brushes.. 3 Polymer Brushes by ...
Five new metal-organic coordination polymers ([Cu{sub 3}(μ{sub 2}-OH){sub 2}(atrz){sub 2}(nph){sub 2}(H{sub 2}O){sub 2}]·2H{sub 2}O){sub n} (1), ([Cu{sub 2}(μ{sub 3}-OH)(atrz)(1,2,4-btc)]·2H{sub 2}O){sub n} (2), ([Cu{sub 2}(μ{sub 3}-OH)(atrz)(1,2,4-btc)(H{sub 2}O)]·H{sub 2}O){sub n} (3), [Cu(dth){sub 0.5}(nph)(H{sub 2}O)]{sub n} (4) and [Cu(dth)(Hnip){sub 2}]{sub n} (5) [atrz=4-amino-1,2,4-triazole, dth=N,N-di(4H-1,2,4-triazole)hexanamide, H{sub 2}nph=3-nitrophthalic acid, 1,2,4-H{sub 3}btc=1,2,4-benzenetricarboxylic acid and H{sub 2}nip=5-nitroisophthalic acid] were hydrothermally synthesized and structurally characterized. Polymer 1 shows a one-dimensional (1D) chain. Polymers 2 and 3 exhibit similar tetranuclear Cu{sup II}{sub 4} cluster-based three-dimensional (3D) frameworks with the same components. Polymer 4 possesses a 3D framework with a 4{sup 12}·6{sup 3}-pcu topology. Polymer 5 displays a 3D framework with a 4{sup 4}·6{sup 10}·8-mab topology. The magnetic properties of 1-4 ...
Novel temperature- and pH-responsive ABA-type triblock copolymers, P(DEAEMA-co-MEO2MA-co-OEGMA)-b-PEG-b-P(DEAEMA-co-MEO2MA-co-OEGMA), composed of a poly(ethylene glycol) (PEG) middle block and temperature- and pH-sensitive outer blocks, were synthesized by atom transfer radical polymerization (ATRP). The composition and structure of the copolymer were characterized by 1H NMR and gel permeation chromatography (GPC). The temperature- and pH-sensitivity, micellization, and the sol-gel transitions of the triblock copolymers in aqueous solutions were studied using transmittance measurements, surface tension, viscosity, fluorescence probe technique, dynamic light scattering (DLS), zeta-potential measurements, and transmission electron microscopy (TEM). The lower critical solution temperature (LCST) of the triblock copolymer, which contains a small amount of a weak base group, (N,N-diethylamino) ethyl methacrylate (DEAEMA), can be tuned precisely and reversibly by changing the solution pH. When the copolymer
A polymer is a molecule, made from joining together many small molecules called monomers. The word polymer can be broken down into poly (meaning many in Greek) and mer (meaning unit). This shows how the chemical composition of a polymer consists of many smaller units (monomers) bonded together into a larger molecule. A chemical reaction bonding monomers together to make a polymer is called polymerization. Some polymers are natural and made by organisms. Proteins have polypeptide molecules, which are natural polymers made from various amino acid monomer units. Nucleic acids are huge natural polymers made up of millions of nucleotide units. Cellulose and starch (two types of carbohydrate) are also natural polymers made up of glucopyranose monomer bonded together in different ways. Rubber is a mixture of polymers. Plastics are man-made polymers. Many fibers are made of polymers. If the units called monomers in a polymer are all the same, then the polymer is called a homopolymer. ...
Many pathogens that infect humans use cell surface carbohydrates as receptors to facilitate cell-cell adhesion. The hallmark of these interactions is their multivalency, or the simultaneous occurrence of multiple interactions. We have used a carbohydrate-functionalized fluorescent polymer, which displays many carbohydrate ligands on a single polymer chain, to allow for multivalent detection of pathogens. Incubation of a mannose-functionalized polymer with Escherichia coli yields brightly fluorescent aggregates of bacteria. These results show that carbohydrate-functionalized fluorescent polymers are a versatile detection method for bacteria. Future design of detectors for other pathogens only requires information on the carbohydrates bound by the organisms, which has been exhaustively reported in the literature.. ...
TY - JOUR. T1 - Interfacial tension governs the formation of self-organized honeycomb-patterned polymer films. AU - Fukuhira, Yukako. AU - Yabu, Hiroshi. AU - Ijiro, Kuniharu. AU - Shimomura, Masatsugu. PY - 2009/6/29. Y1 - 2009/6/29. N2 - Hexagonally packed water droplets condensed on a polymer solution are potential templates for the formation of honeycomb-patterned porous polymer films. A small number of surface-active molecules is indispensable for the stabilization of water droplets during solvent evaporation. Biocompatible surfactants; e.g., phospholipids, are required for the fabrication of biodegradable honeycomb-patterned polymer films, which can be used as novel biomedical materials, mainly in vivo. Among various kinds of phospholipids, dioleoylphosphatidylethanolamine (DOPE) has been reported to be the most suitable surfactant for the formation of honeycomb-patterned PLA films. Interfacial tension between a water droplet and the polymer solution is largely dependent on the chemical ...
April 1, 2019-Polymer composites are projected to increase in the automotive industry, MarketWatch reports. Polymer composites are materials with the combination of a polymer matrix and a reinforcing agent, mainly fibers (usually carbon, glass or natural fibers). The research report on Global Automotive Polymer Composites Market 2019 keenly analyzes significant features of the industry. The analysis servers market size, latest trends, drivers, threats, opportunities, as well as key market segments. It is based on past data and present market needs. Also, involve distinct business approaches accepted by the . . .
Thermal (or pressure) induced demixing of partially miscible binary polymer mixtures is a simple and controlled approach to inducing well-defined polymeric structures. By understanding the role of polymer architecture (tacticity, chain length and polydispersity) on the blend thermodynamics, the demixing pathway can be chosen to yield nanostructured materials with precise control of length scale and connectivity with application in membranes, scaffolds and photovoltaics. We probe the thermodynamics and morphological evolution of polymer blend films with small-angle neutron scattering (SANS), light scattering and optical microscopy and compare our experimental results to existing theoretical descriptions of polymer blend thermodynamics and demixing kinetics.. ...
TY - JOUR. T1 - Precise grafting of macrocyclics and dendrons to a linear polymer chain. AU - Amir, Faheem. AU - Hossain, Md D.. AU - Jia, Zhongfan. AU - Monteiro, Michael J.. PY - 2016/8/31. Y1 - 2016/8/31. N2 - Sequential growth of multifunctional telechelic polymer chains was used here to produce three, four or seven HO-functionalities equally spaced along the polymer backbone. The telechelic building block consisted of a halide group on one end and both a hydroxyl and alkyne group on the other end. The key was to maintain the halide end-group on the telechelic polymer chain during the CuAAC coupling reaction after each sequential growth. This was accomplished by using the combination of the PMDETA ligand and toluene as a solvent to produce significantly faster rates of CuAAC coupling reaction over halide abstraction. The HO-functionalities were then converted to azide groups allowing further CuAAC reactions with either alkyne polymeric dendrons or cyclics to produce equally spaced grafts ...
The work presented in this thesis concerns surface energy modification and patterning of the surfaces of conjugated polymers. Goniometry and Wilhelmy Balance techniques were used to evaluate the surface energy or wettability of a polymers surface; infrared reflectionabsorption spectroscopy (IRAS) was used to analyse the residuals on the surface as modified by a bare elastomeric stamp poly(dimethylsiloxane) (PDMS). The stamp was found to be capable of modifying a polymer surface. Patterning of a single and/or double layer of conjugated polymers on the surface can be achieved by surface energy controlled dewetting. Modification of a conjugated polymer film can also be carried out when a sample is subjected to electrochemical doping in an aqueous electrolyte. The dynamic surface energy changes during the process were monitored in-situ using the Wilhelmy balance method.. This thesis also concerns studies of conjugated polymer-based optoelectronics, including light-emitting diodes (PLEDs), that ...
The direct reaction between copper nitrate, thymine-1-acetic acid, and 4,4′-bipyridine in water leads to the formation of a blue colloid comprising uniform crystalline nanoribbons (length >1 mum; width ca. 150-185 nm; diameter ca. 15-60 nm) of a coordination polymer. The polymer displays a thymine-based structure freely available for supramolecular interactions. These nanostructures show significant selective interaction with single-stranded oligonucleotides based on adenine. Remarkably, they present low cell toxicity in three cell lines-despite the copper(II) content-and can be used as nanocarriers of oligonucleotides. These results suggest the potential of these types of nanostructures in several biological applications ...
This invention includes malleable, biodegradable, fibrous compositions for application to a tissue site in order to promote or facilitate new tissue growth. One aspect of this invention is a fibrous component that provides unique mechanical and physical properties. The invention may be created by providing a vessel containing a slurry, said slurry comprising a plurality of natural or synthetic polymer fibers and at least one suspension fluid, wherein the polymer fibers are substantially evenly dispersed and randomly oriented throughout the volume of the suspension fluid; applying a force, e.g., centrifugal, to said vessel containing said slurry, whereupon said force serves to cause said polymer fibers to migrate through the suspension fluid and amass at a furthest extent of the vessel, forming a polymer material, with said polymer material comprising polymer fibers of sufficient length and sufficiently viscous, interlaced, or interlocked to retard dissociation of said polymer fibers.
A composite is formed wherein particles of a conductive polymer are uniformly distributed within a processable non-conductive polymer. In the method of the invention, an inverted emulsion is formed by dispersing an aqueous solution of oxidant in an organic solvent comprising a host polymer and an oil-soluble surfactant. A monomer whose polymerization yields a conductive polymer which is dissolved in a solvent miscible with the organic solvent of the emulsion is then added dropwise to the emulsion with agitation. The composite is separated from the emulsion and the precipitate is washed and dried.
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phdthesis{d217f1f6-5ffd-404d-8913-770a926a130e, abstract = {Most polymeric materials used today are not simple homopolymers, but consist of more than one polymer, which lead to morphologies of different length scale and shape. It is important to receive knowledge of the morphologies because the properties of the materials change depending on the structure. This thesis describes methods developed to study polymer morphologies by electron microscopy and also how to make a correct interpretation of the result. TEM (Transmission Electron Microscope) and SEM (Scanning Electron Microscope) are described for studying morphologies in PVC (polyvinyl chloride) resin, polymer blends, compatibilizer in polymer blends, latex particles, latex films and bitumen/polymer blends. Following polymer blends were studied: Carbon black filled NBR/EPDM (nitril butadiene rubber/ethylene-propylene-diene terpolymer), PP/PA (polypropylene/polyamid) Modified with SEBS-MA ...
A process for producing a substantially dry polymer particle powder. A mixture of polymerization reagents is formed from a mixture of at least one monomer source and a solvent selected from the group consisting essentially of water and organic solvents and an initiator source. The mixture of polymerization reagents is sprayed into a heated, controlled atmosphere, forming droplets of the mixture which are allowed to fall through the heated, controlled atmosphere for a sufficient period of time to obtain a desired degree of polymerization. The solvent is continuously evacuated from the atmosphere during the polymerization process.
Zinc-porphyrin dye molecules were incorporated into the backbone of a conjugated polymer material by a method, which allowed for the incorporation of only one zinc-porphyrin dye molecule into the backbone of each conjugated polymer molecule. The electronic properties of the homopolymer were established using ultraviolet photoelectron spectroscopy (UPS) for the determination of the electronic energy levels and the injection barrier for holes into the valence band. Pulse radiolysis time resolved microwave conductivity (PR-TRMC) was used to determine the sum of charge carrier mobilities. Electroluminescent devices of the homopolymer itself and of the zinc-porphyrin containing polymer were prepared and the nature of the electroluminescence was characterized. The homopolymer segments were found to optically pump the emission of the zinc-porphyrin dye moities. The homopolymer exhibits blue-green emission and the zinc-porphyrin linked homopolymers emit near-infrared/infrared light. This was ...
In this study, the outstanding ability of the coordination polymer [Pt2(nBuCS2)4I]n (nBu = n-butyl) (1) to reversibly self-organize from solution was demonstrated. This feature allowed us to generate highly electrical conductive structures located upon demand on technologically relevant surfaces, by easy-to-
TY - JOUR. T1 - Diorganotin-based coordination polymers derived from sulfonate/phosphonate/phosphonocarboxylate ligands. AU - Shankar, R. AU - Jain, A. AU - Kociok-Kohn, Gabriele. AU - Molloy, Kieran C. PY - 2011/2/21. Y1 - 2011/2/21. N2 - The reactions of diorganotin precursors [R2Sn(OR1)(OSO2R1)](n)[R = R-1 = Me (1); R = Me, R-1 = Et (2)] with an equimolar amount of t-butylphosphonic acid (AT, 8-10 h) in methanol result in the formation of identical products, of composition [(Me2Sn)(3)(O3PBut)(2)(O2P(OH)Bu-t)(2)](n) (3). On the other hand, a similar reaction of 2, when carried out in dichloromethane, affords [(Me2Sn)(3)(O3PBut)(2)(OSO2Et)(2)center dot MeOH](n) (4). A plausible mechanism implicating the role of solvent in the formation of these compounds has been put forward. In addition, the synthesis of [(Me2Sn)(3)(O3PCH2CH2COOMe)(2)(OSO2Me)(2)](n) (5) and [R2Sn(O2P(OH)CH2CH2COOMe)(OSO2R1)](n) [R = Et, R-1 = Me (6); R = Bu-n, R-1 = Et (7)] has been achieved by reacting 1 and related ...
The global Water Soluble Polymer Market size is expected to value at USD 43.79 billion by 2022. The market is subject to witness a substantial growth due to the rise in the number of application of water soluble polymers in drilling, enhanced oil recovery, mining, wastewater treatment, and food. Increasing adoption of water-soluble polymers as stabilizing agents, thickeners, film formation agent, emulsifiers, rheology modifiers, lubricity aids, and conditioners, are expected to fuel market demand for water soluble polymers over the forecast period. Globally, the water soluble polymers industry is predicted to grow at higher CAGR in the forecast period, providing numerous opportunities for market players to invest for research and development in the water soluble polymers market.. Water soluble polymers are vital for production of various household products, detergents, personal care, and paints & coatings. Increasing adoption of water soluble polymers in food & beverages industry, building & ...
CHEM 5384 Polymer Characterization II Lab 1: Atom Transfer Radical Polymerization of styrene Mengfang Li 01/29/2012 Introduction: In this experiment we were introduced the method to control a radical process to prepare well- defined and functionalizable polymers. Over 100 billion pounds of synthetic polymers were produced each year in United alone. Chain polymerization accounts 80% of these and by far free radical polymerization is the most commonly used reaction method in this category [1] . Radicals are very reactive and add quickly across the double bond to form polymers. This process will terminate if the chain end reacts with another radical. This can be observed by plotting the molecular weight as a function of conversion of monomer into polymer. As shown in Figure 1 for conventional method, high molecular weights are obtained at low conversion and remain at approximately same level throughout the reaction. The initiator (eg. BPO or AIBN) decomposes ...
A photorefractive (PR) device comprises of a layer of a novel photorefractive polymer composite sandwiched inbetween two transparent electrodes. The PR polymer composite comprises a photoconducting polymer, a photosensitizer, a novel second-order, non-linear optical chromophore, and a plasticizer in an amount sufficient to provide the PR polymer composite with a glass transition temperature below about 45 C. The PR polymer composite is capable of internally storing image patterns generated by interfering two coherent light beams inside the material. The PR polymer composite shows high diffraction efficiencies (near 100%) and high net two-coupling gain (|200 cm-1). The writing of information is reversible. Consequently, the device is suitable for read/write holographic storage and real-time image processing applications, and is capable of being poled at essentially room temperature. The light source is an integrated semiconductor laser and the detector is a commercial Si photodiode or a CCD camera.
ELECTRODE SURFACE. 5. MONOMER COMPOSITIONS FOR EIP. 6. MECHANISM AND KINETICS OF FILM FORMATION AT ELECTROCOPOLYMERIZATION OF ACRYLIC ACID, ACRYLAMIDE AND FORMALDEHYDE. 7. PHYSICAL-CHEMICAL REGULARITIES OF POLYMER FILMS FORMATION AT ELECTROCOPOLYMERIZATION OF ACRYLAMIDE AND FORMALDEHYDE IN THE AQUEOUS MEDIUM. 8. FORMATION OF POLYMER FILMS FROM AQUEOUS SOLUTION OF N-METHYLOLACRYLAMIDE [132]. 9. PRINCIPLES OF THE POLYMER LAYER FORMATION IN THE PROCESS OF EIP [98]. 10. CURRENT-VOLTAGE CHARACTERISTICS OF ELECTRODE MODIFIED BY THE POLYMER FILM [43, 133, 134]. 11. IN SITU STUDY OF ELECTROPOLYMERIZATION KINETICS OF ACRYLAMIDE, FORMALDEHYDE, AND N,N-METHYLENEBISACRYLAMIDE [136]. 12. SYNTHESIS OF ULTRAFILTRATION MEMBRANES BY ELECTROCHEMICALLY INITIATED POLYMERIZATION OF ACRYLIC MONOMERS [22, 23, 141]. 13. PROPERTIES OF ELECTROSYNTHESIZED ULTRAFILTRATION MEMBRANES AND FIELDS OF THEIR PRACTICAL ...
TY - GEN. T1 - Structural properties and photoinduced electron processes in polymer films of poly(3-hexylthiophene-2, 5-diyl) on the surface of silver island films. AU - Zeinidenov, A. K.. AU - Ibrayev, N. Kh. AU - Afanasyev, D. A.. PY - 2016/11/28. Y1 - 2016/11/28. N2 - Influence of surface plasmon resonance of silver island films on photoinduced electronic processes in polymer films of poly(3-hexylthiophene-2,5-diyl) (P3HT) was studied in this work. Fabrication of P3HT on the surface of the plasmon silver island films increases intensity of the absorption and fluorescence of the polymer film about 4 times. The increase in absorption and fluorescence intensity of P3HT is associated with an increase of the rate of absorption transitions in the polymer films through the influence of the local electromagnetic field near the surface of the silver island films. A formation of disordered polymer structures occurs on the surface of the silver island films. This is determined from the ...
A polymer scaffold is provided comprising an extensively interconnected macroporous network. The polymer scaffold embodies macropores having a diameter in a range of 0.5-3.5 mm, and preferably in a range of about 1.0-2.0 mm. The polymer scaffold is prepared using a novel process which advantageously combines the techniques of particulate leaching and phase inversion to render a process that provides amplified means by which to control the morphology of the resulting polymer scaffold. The polymer scaffold has utility in the area of tissue engineering, particularly as a scaffold for both in vitro and in vivo cell growth. The polymer scaffold may be produced using pure polymer or alternatively a composite material may be formed consisting of a macroporous polymer scaffold and osteoclast-resorbable calcium phosphate particles with a binding agent binding the calcium phosphate particles to the polymer scaffold.
A growing number of players are capitalizing on the opportunities arising out of the substantial popularity of biodegradable plastics and bioplastics where lactic acid and polylactic acid are used as raw materials for their production. Some of the leading players in the global lactic acid market and polylactic acid market are Futerro SA, Teijin Ltd., Zhejiang Hisun Biomaterials Co., Ltd., Synbra Technology BV, Archer Daniels Midland Company, Henan Jindan Lactic Acid Technology Co., Ltd., NatureWorks LLC, and Corbion NV., notes Transparency Market Research (TMR).. The global lactic acid market stood at US$1,130.4 Mn in 2014 and is estimated to reach US$3,381.8 Mn by the end of 2023. This represents the market to rise at robust CAGR of 13.0% during 2015-2023. On the other hand, the global polylactic acid market stood at US$400.1 Mn in 2014 and is projected to reach a worth of US$1,358.1 Mn by 2023 end. Polylactic acid market is projected to proliferate at a CAGR of 14.6% during the same forecast ...
The chemist Hermann Staudinger first proposed that polymers consisted of long chains of atoms held together by covalent bonds, which he called macromolecules. His work expanded the chemical understanding of polymers and was followed by an expansion of the field of polymer chemistry during which such polymeric materials as neoprene, nylon and polyester were invented. Before Staudinger, polymers were thought to be clusters of small molecules (colloids), without definite molecular weights, held together by an unknown force. Staudinger received the Nobel Prize in Chemistry in 1953. Wallace Carothers invented the first synthetic rubber called neoprene in 1931, the first polyester, and went on to invent nylon, a true silk replacement, in 1935. Paul Flory was awarded the Nobel Prize in Chemistry in 1974 for his work on polymer random coil configurations in solution in the 1950s. Stephanie Kwolek developed an aramid, or aromatic nylon named Kevlar, patented in 1966. Karl Ziegler and Giulio Natta ...
Preface. Acknowledgments.. List of Contributors.. List of Figures.. List of Tables.. Editor Biographies.. PART I: FUNDAMENTALS OF SUPRAMOLECULAR POLYMERS.. 1. A Brief Introduction to Supramolecular Chemistry in a Polymer Context1 (Raymond J. Thibault and Vincent M. Rotello).. 1.1 Introduction and Background.. 1.2 Main-chain versus Side-chain Supramolecular Polymers.. References.. 2. Molecular Recognition Using Amphiphilic Macromolecules (Malar A Azagarsamy, K. Krishnamoorthy, and S. Thayumanavan).. 2.1 Introduction.. 2.2 Amphiphilic Block Copolymers.. 2.2.1 Non-Specific Interactions.. 2.2.2 Specific Interactions.. 2.3 Amphiphilic Homopolymers.. 2.3.1 Container Properties.. 2.4 Amphiphilic Dendrimers.. 2.5 Conclusions.. 2.6 Acknowledgements.. References.. 3. Supramolecular Control of Mechanical Properties in Single Molecules, Interfaces and Macroscopic Materials (David M. Loveless, Farrell R. Kersey and Stephen L. Craig).. 3.1 Introduction and Background.. 3.2 Mechanical Properties of Linear ...
A method for producing a polylactic acid of the present invention includes the steps of (a) polymerizing a lactide used as a main starting material in a molten state to give a polylactic acid; and (b) further polymerizing the polylactic acid obtained in step (a) in a solid phase by heating at a temperature lower than a melting point of a final polymer product.
This dissertation reports the synthesis and characterization of nanoscale coordination polymers (NCPs) for anticancer drug delivery. Nanoparticles have been explored in order to address the limitations of small molecule chemotherapeutics. NCPs have been investigated as drug delivery vehicles as they can exhibit the same beneficial properties as the bulk metal-organic frameworks as well as interesting characteristics that are unique to nanomaterials. Gd-MTX (MTX = methotrexate) NCPs with a MTX loading of 71.6 wt% were synthesized and stabilized by encapsulation within a lipid bilayer containing anisamide (AA), a small molecule that targets sigma receptors which are overexpressed in many cancer tissues. Functionalization with AA allows for targeted delivery and controlled release to cancer cells, as shown by enhanced efficacy against leukemia cells. The NCPs were doped with Ru(bpy) (bpy = 2,2-bipyridine), and this formulation was utilized as an optical imaging agent by confocal microscopy. NCPs ...
CRG has unveiled a new shape memory 3D printing filament called Essemplex that has been designed to provide users with a 3D printing filament that combines the
The invention relates to radiopaque shape memory foam compositions and methods of using the compositions. In certain embodiments, the compositions are used in neurovascular occlusion applications.
Structures and properties of three new homobinuclear nanosized supramolecular copper coordination polymers derived from carboxylate type ligands and benzimidazole
Functional polymer thin films find uses in wide range of energy applications as separation membranes for fuel cells or as electrodes in batteries. Low costs, flexible nature and tailored functionalities make the polymer thin films better alternatives compared to their metal counterparts. Our research efforts focus mainly on conductive polymer thin films and selectively permeable ultra thin functional polymers.
The proton conductivity of a dense coordination polymer (CP) was investigated under high-pressure conditions. Impedance measurements under high pressures revealed that the proton conductivity of the CP decreased more than 1000-fold at pressures of 3-7 GPa and that the activation energy for proton conduction almost doubled compared with that at ambient pressure. A synchrotron X-ray study under high pressure identified the amorphization process of the CP during compression, which rationally explains the decrease in conductivity and increase in activation energy. This phenomenon is categorized as reversible pressure-induced amorphization of a dense CP and is regarded as a demonstration of the coupling of the mechanical and electrical properties of a CP. ...
Sabu Thomas, PhD, is a Professor of Polymer Science and Engineering at the School of Chemical Sciences and Director of the International and Inter University Centre for Nanoscience and Nanotechnology at Mahatma Gandhi University, Kottayam, Kerala, India. The research activities of Professor Thomas include surfaces and interfaces in multiphase polymer blend and composite systems; phase separation in polymer blends; compatibilization of immiscible polymer blends; thermoplastic elastomers; phase transitions in polymers; nanostructured polymer blends; macro-, micro- and nanocomposites; polymer rheology; recycling; reactive extrusion; processing-morphology-property relationships in multiphase polymer systems; double networking of elastomers; natural fibers and green composites; rubber vulcanization; interpenetrating polymer networks; diffusion and transport; and polymer scaffolds for tissue engineering. He has supervised 68 PhD theses, 40 MPhil theses, and 45 Masters thesis. He has three patents to ...
TY - JOUR. T1 - Polyphosphate exerts differential effects on blood clotting, depending on polymer size. AU - Smith, Stephanie A.. AU - Choi, Sharon H.. AU - Davis-Harrison, Rebecca. AU - Huyck, Jillian. AU - Boettcher, John. AU - Reinstra, Chad M.. AU - Morrissey, James H.. PY - 2010/11/18. Y1 - 2010/11/18. N2 - Polyphosphate, a linear polymer of inorganic phosphate, is secreted by activated platelets and accumulates in many infectious microorganisms. We recently showed that polyphosphate modulates the blood coagulation cascade at 3 steps: it triggers the contact pathway, it accelerates factor V activation, and it enhances fibrin polymerization. We now report that polyphosphate exerts differential effects on blood clotting, depending on polymer length. Very long polymers (≥ 500mers, such as those present in microorganisms) were required for optimal activation of the contact pathway, while shorter polymers (∼ 100mers, similar to the polymer lengths released by platelets) were sufficient to ...
This dissertation developed novel microfabrication techniques of conductive polymer nanocomposite and utilized this material as a functional element for various physical sensor applications. Microstructures of nanocomposite were realized through novel microcontact printing and laser ablation assisted micropatterning processes. Prototype devices including large-strain strain sensor and highly-sensitive pressure sensor were demonstrated showing distinct advantages over existing technologies. The polymer nanocomposite used in this work comprised elastomer poly(dimexylsiloxane) (PDMS) as polymer matrix and multi-walled carbon nananotubes (MWCNTs) as a conductive nanofiller. To achieve uniform distribution of carbon nanotubes within the polymer, an optimized dispersion process was developed, featuring a strong organic solvent-chloroform, which dissolved PDMS base polymer easily and allowed monodispersion of MWCNTs. Following material preparation, three novel approaches were employed to pattern
TY - JOUR. T1 - A novel temperature-step method to determine the glass transition temperature of ultrathin polymer films by liquid dewetting. AU - Wang, Jinhua. AU - McKenna, Gregory B.. N1 - Copyright: Copyright 2013 Elsevier B.V., All rights reserved.. PY - 2013/9/15. Y1 - 2013/9/15. N2 - A novel temperature-step experimental method that extends the Bodiguel-Fretigny liquid dewetting method of investigating polymer thin films is described and results presented from an investigation of thickness effects on the glass transition temperature (Tg) of ultrathin polystyrene (PS) films. Unlike most other methods of thin film investigation, this procedure promises a rapid screening tool to determine the overall profile of T g versus film thickness for ultrathin polymer films using a limited number of samples. Similar to our prior observations and other literature data, with this new method obvious Tg depression was observed for PS thin films dewetting on both glycerol and an ionic liquid. The results ...
TY - JOUR. T1 - Temperature-responsive smart packing materials utilizing multi-functional polymers. AU - Ayano, Eri. AU - Kanazawa, Hideko. PY - 2014/1. Y1 - 2014/1. N2 - Polymers that respond to small changes in environmental stimuli with large, sometimes discontinuous changes in their physical state or properties, are often called smart polymers. Poly(N-isopropylacrylamide), PNIPAAm, is one of the most representative smart polymer that exhibits a thermally reversible soluble-insoluble change in the vicinity of its lower critical solution temperature (LCST) at 32°C in aqueous solution. Temperature-responsive chromatography for the separation of biomolecules utilizing the poly(N-isopropylacrylamide) (PNIPAAm)-modified stationary phase is performed with an aqueous mobile phase without using an organic solvent. The surface properties and function of the stationary phase are controlled by external temperature changes without changing the mobile-phase composition. The separation of the ...
TY - JOUR. T1 - All-star polymer multilayers as pH-responsive nanofilms. AU - Kim, Byeong Su. AU - Gao, Haifeng. AU - Argun, Avni A.. AU - Matyjaszewski, Krzysztof. AU - Hammond, Paula T.. PY - 2009/1/13. Y1 - 2009/1/13. N2 - Star polymers with globular architecture and multiple arms are among the simplest forms of polymers with branched topologies. The combination of their unique architecture and high local densities of active functional groups makes star polymers unique candidates for a diverse range of applications. In this article, we describe the synthesis of star polymers with precisely controlled structures via atom transfer radical polymerization (ATRP) using the one-pot arm-first method. Specifically, two types of highly defined, high charge density star polymers with oppositely charged arm structures were prepared: poly[2-(dimefliylamino)ethyl methacrylate] (PDMAEMA) star and poly(acrylic acid) (PAA) star polymers with cross-linked cores. By exploiting the electrostatic interactions ...
Shape memory polymers (SMPs) is a class of polymeric materials that are capable of changing shapes under an external stimulus such as heat, light, solvents and electromagnetic induction. In this dissertation, we explore both the bulk and surface shape memory effect of polymers, understand the material properties, and develop potential applications. In the first case (Chapter 2, Chapter 3, and Chapter 4), wrinkles were developed utilizing the surface SM effect and were applied for cell culture. Wrinkling has been generally understood as a stress-driven instability phenomenon. In our bilayer system, the wrinkle formation is enabled by compressive buckling of a gold coating that is first applied to an SMP that has been fixed with a temporary uniaxial strain. The bilayer system is then recovered thermally to generate the wrinkles. The fundamentals of wrinkle characteristics and formation were investigated in Chapter 2. Gold film thickness and applied prestrain of the SMP substrate show a direct impact on
Report provides the brief overview about the demand and growth of the lactic and polylactic acid worldwide . Its also contain global market scenario of lactic and polylactic acid including Some of the...
A series of water-soluble, stimuli-responsive (co)polymers was synthesized via the reversible addition-fragmentation chain transfer (RAFT) polymerization. The end group of a RAFT polymer, poly(N -isopropylacrylamide), was modified to ene or yne function via thiol-ene click chemistry. The ene or yne end group subsequently underwent thiol-ene or thiol-yne addition affording mono- or di-functional end group. First, three methacrylic monomers containing 2 or 3 pendent tertiary amine functional groups, 1,3-bis(dimethylamino)propan-2-ylmethacrylate ( M1 ), 1-(bis(3-(dimethylamino)propyl)amino)propan-2-yl methacrylate (M2 ), and 2-((2-(2-(dimethylamino)ethoxy)ethyl)methylamino)ethyl acrylate (M3 ), were synthesized via an acylation reaction between methacryloyl chloride and the corresponding aminoalcohol. All of these three monomers were successfully homopolymerized under RAFT conditions with 1-methyl-l-cyanoethyl dithiobenzoate (CPDB) as chain transfer agent (CTA). For each monomer, homopolymerization using
TY - JOUR. T1 - In Situ Surface-Selective Modification of Uniform Size Macroporous Polymer Particles with Temperature-Responsive Poly-N-isopropylacrylamide. AU - Hosoya, Ken. AU - Sawada, Etsuko. AU - Kimata, Kazuhiro. AU - Araki, Takeo. AU - Tanaka, Nobuo. AU - Frechet, Jean. PY - 1994/7/1. Y1 - 1994/7/1. N2 - A new in situ surface-selective modification procedure for the incorporation of temperature-responsive poly-N-isopropylacrylamide (poly-NIPAM) into porous polymer beads has been developed. This procedure allows the incorporation of the poly-NIPAM either on the internal surface of the macroporous beads or on their external surface selectively. The process involves the addition of NIPAM monomer and a water-soluble radical initiator to a polymerizing mixture consisting of uniformly sized monomer and porogen particles prepared by a two-step swelling and polymerization method. NIPAM polymerizes in the aqueous phase but soon precipitates out because the upper critical solution temperature of ...
Purchase List of Standard Abbreviations (Symbols) for Synthetic Polymers and Polymer Materials 1974 - 1st Edition. Print Book & E-Book. ISBN 9780080223711, 9781483182025
We characterize the structure and mechanical properties of 1,3,5-benzenetricarboxamide (BTA) supramolecular polymers using correlative AFM and fluorescence imaging. AFM allows for nanoscale structural investigation but we found that statistical analysis is difficult because these structures are easily disrupted by the AFM tip. We therefore correlate AFM and fluorescence microscopy to couple nanoscale morphological information to far-field optical images. A fraction of the immobilized polymers is in a clustered or entangled state, which we identify based on diffraction limited fluorescence images. We find that clustered and entangled polymers exhibit a significantly longer persistence length that is broader distributed than single unentangled polymers. By comparison with numerical simulations we find significant heterogeneity in the persistence length of single unentangled polymers, which we attribute to polymer-substrate interactions and the presence of structural diversity within the polymer. ...
TY - JOUR. T1 - Injectable cartilage using polyethylene oxide polymer substrates. AU - Sims, C. Derek. AU - Butler, Peter E.M.. AU - Casanova, Rene. AU - Lee, Betty T.. AU - Randolph, Mark A.. AU - Lee, W. P.Andrew. AU - Vacanti, Charles A.. AU - Yaremchuk, Michael J.. PY - 1996/10. Y1 - 1996/10. N2 - This study demonstrates that polyethylene oxide gels, which are biocompatible and biodegradable synthetic polymers, can be utilized for the encapsulation of isolated chondrocytes and maintenance of three-dimensional spatial support for new tissue development. Chondrocytes isolated from the glenohumeral and humeroradioulnar joints of a calf were added to a 20% polyethylene oxide solution in Hams F-12 medium to generate a final cellular density of 10 x 106/ml. The polymer-chondrocyte constructs were injected through a 22-gauge needle in 500-μl aliquots subcutaneously in 12 nude mice and incubated for 6 and 12 weeks in vivo. Histologic and biochemical analyses including deoxyribonucleic acid and ...
3Institut für Makromolekulare Chemie, Universität Freiburg, Freiburg, Germany. Much insight into crystallization of long chain polymers can be gained by studying mono-lamellar single crystals. Because of the kinetically determined lamellar thickness and the corresponding variations in melting temperature, polymer crystals allow for self-seeding, i.e., crystals can be re-grown from a melt, which contains a few thermodynamically stable remnants of pre-existing crystals acting as seeds. Employing such a self-seeding approach, we demonstrated that large single crystals can be grown even from long poly(3-hexylthiophene) (P3HT) chains, with a control over the number density, size, and internal structure of these crystals exhibiting monoclinic form II with interdigitated hexyl side groups [1].. We also studied bulky substituted poly(3-(2,5-dioctylphenyl)thiophene) (PDOPT) where weakened interchain interactions lead to a much lower melting temperature as compared to P3HT [2]. Using absorption and ...
High-intensity near-IR fluorescence in semiconducting polymer dots achieved by cascade FRET strategy :Near-IR (NIR) emitting semiconducting polymer dots (Pdots) with ultrabright fluorescence have been prepared for specific cellular targeting. A series of π-conjugated polymers were synthesized to form water dispersible multicomponent Pdots by an ultrasonication-assisted co-precipitation method. By optimizing cascade energy transfer in Pdots, high-intensity NIR fluorescence (Φ = 0.32) with tunable excitations, large absorption-emission separation (up to 330 nm), and narrow emission bands (FWHM = 44 nm) have been achieved. Single-particle fluorescence imaging show that the as-prepared NIR Pdots were more than three times brighter than the commercially available Qdot705 with comparable sizes under identical conditions of excitation and detection. Because of the covalent introduction of carboxylic acid groups into polymer side chains, the bioconjugation between NIR-emitting Pdots and streptavidins ...
The effect of nonionic surfactants on the cationic conjugated polymer (CCP), poly{9,9-bis[6-(N,N-trimethylammonium)hexyl]fluorene-co 1,4-phenylene} iodide 1, has been investigated. It is shown that the CCP in various solvents exists in three phases: isolated polymer chains, polymer aggregate, and variable size clusters (partially dissolved polymer). It is shown that nonionic surfactants enhance the photoluminescence (PL) quantum yield of the CCP in water by breakup of polymer aggregates, which eliminates the nonemissive interchain quenching with aggregates and increases surface-to-volume ratio of the CCP. Furthermore, the surfactants reduce quenching by incorporation of the CCP into aggregates or binary micelles. Surfactant also reduces the polar interaction strength between CCP and water and enhances CCP quenching by the counterions (iodine) by ion pairing effect. The dynamics of the interactions are complex and reveal that the surfactant induces rapid increase in the PL which imply that the ...
Thermoplastic elastomeric films comprise from about 40% to about 80% of an elastomeric block copolymer and from about 20% to about 60% of an ethylene-vinyl acetate copolymer. The block copolymer has at least two monoalkenyl arene polymer end blocks and at least one elastomeric conjugated diene midblock. The monoalkenyl arene polymer blocks comprise from about 8% to about 55% by weight of the block copolymer. The block copolymer has a melt index of less than about 10. The ethylene-vinyl acetate copolymer comprises from about 22% to about 33% vinyl acetate and has a melt index of less than about 0.6. The film is from about 0.03 mm to about 0.15 mm in thickness.