Functional Polymer Opals and Porous Materials by Shear-Induced Assembly of Tailor-Made Particles.

Science.gov (United States)

Gallei, Markus

2018-02-01

Photonic band-gap materials attract enormous attention as potential candidates for a steadily increasing variety of applications. Based on the preparation of easily scalable monodisperse colloids, such optically attractive photonic materials can be prepared by an inexpensive and convenient bottom-up process. Artificial polymer opals can be prepared by shear-induced assembly of core/shell particles, yielding reversibly stretch-tunable materials with intriguing structural colors. This feature article highlights recent developments of core/shell particle design and shear-induced opal formation with focus on the combination of hard and soft materials as well as crosslinking strategies. Structure formation of opal materials relies on both the tailored core/shell architecture and the parameters for polymer processing. The emphasis of this feature article is on elucidating the particle design and incorporation of addressable moieties, i.e., stimuli-responsive polymers as well as elaborated crosslinking strategies for the preparation of smart (inverse) opal films, inorganic/organic opals, and ceramic precursors by shear-induced ordering. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Production and characterization of monodisperse uranium particles for nuclear safeguards applications

International Nuclear Information System (INIS)

Knott, Alexander

2016-01-01

Environmental sampling is a very effective measure to detect undeclared nuclear activities. Generally, samples are taken as swipe samples on cotton. These swipes contain minute quantities of particulates which have an inherent signature of their production and release scenario. These inspection samples are assessed for their morphology, elemental composition and their isotopic vectors. Mass spectrometry plays a crucial role in determining the isotopic ratios of uranium. Method validation and instrument calibration with well-characterized quality control (QC)-materials, reference materials (RMs) and certified reference materials (CRMs) ensures reliable data output. Currently, the availability of suitable well defined microparticles containing uranium and plutonium reference materials is very limited. Primarily, metals, oxides and various uranium and plutonium containing solutions are commercially available. Therefore, the IAEA's Safeguards Analytical Services (SGAS) cooperates with the Institute of Nuclear Waste Management and Reactor Safety (IEK-6) at the Forschungszentrum Juelich GmbH in a joint task entitled ''Production of Particle Reference Materials''. The work presented in this thesis has been partially funded by the IAEA, Forschungszentrum Juelich GmbH and the Federal Ministry of Economic Affairs and Energy (BMWi) through the ''Joint Program on the Technical Development and Further Improvement of IAEA Safeguards between the Government of the Federal Republic of Germany and the IAEA''. The first step towards monodisperse microparticles was the development of pure uranium oxide particles made from certified reference materials. The focus of the dissertation is (1) the implementation of a working setup to produce monodisperse uranium oxide particles and (2) the characterization of these particles towards the application as QC-material. Monodisperse uranium oxide particles were produced by spray pyrolysis. It was demonstrated that the particle size can be

Production and characterization of monodisperse uranium particles for nuclear safeguards applications

Energy Technology Data Exchange (ETDEWEB)

Knott, Alexander

2016-07-01

Environmental sampling is a very effective measure to detect undeclared nuclear activities. Generally, samples are taken as swipe samples on cotton. These swipes contain minute quantities of particulates which have an inherent signature of their production and release scenario. These inspection samples are assessed for their morphology, elemental composition and their isotopic vectors. Mass spectrometry plays a crucial role in determining the isotopic ratios of uranium. Method validation and instrument calibration with well-characterized quality control (QC)-materials, reference materials (RMs) and certified reference materials (CRMs) ensures reliable data output. Currently, the availability of suitable well defined microparticles containing uranium and plutonium reference materials is very limited. Primarily, metals, oxides and various uranium and plutonium containing solutions are commercially available. Therefore, the IAEA's Safeguards Analytical Services (SGAS) cooperates with the Institute of Nuclear Waste Management and Reactor Safety (IEK-6) at the Forschungszentrum Juelich GmbH in a joint task entitled ''Production of Particle Reference Materials''. The work presented in this thesis has been partially funded by the IAEA, Forschungszentrum Juelich GmbH and the Federal Ministry of Economic Affairs and Energy (BMWi) through the ''Joint Program on the Technical Development and Further Improvement of IAEA Safeguards between the Government of the Federal Republic of Germany and the IAEA''. The first step towards monodisperse microparticles was the development of pure uranium oxide particles made from certified reference materials. The focus of the dissertation is (1) the implementation of a working setup to produce monodisperse uranium oxide particles and (2) the characterization of these particles towards the application as QC-material. Monodisperse uranium oxide particles were produced by spray pyrolysis. It was

Self-Templated Stepwise Synthesis of Monodispersed Nanoscale Metalated Covalent Organic Polymers for In Vivo Bioimaging and Photothermal Therapy.

Science.gov (United States)

Shi, Yanshu; Deng, Xiaoran; Bao, Shouxin; Liu, Bei; Liu, Bin; Ma, Ping'an; Cheng, Ziyong; Pang, Maolin; Lin, Jun

2017-09-05

Size- and shape-controlled growth of nanoscale microporous organic polymers (MOPs) is a big challenge scientists are confronted with; meanwhile, rendering these materials for in vivo biomedical applications is still scarce. In this study, a monodispersed nanometalated covalent organic polymer (MCOP, M=Fe, Gd) with sizes around 120 nm was prepared by a self-templated two-step solution-phase synthesis method. The metal ions (Fe 3+ , Gd 3+ ) played important roles in generating a small particle size and in the functionalization of the products during the reaction with p-phenylenediamine (Pa). The resultant Fe-Pa complex was used as a template for the subsequent formation of MCOP following the Schiff base reaction with 1,3,5-triformylphloroglucinol (Tp). A high tumor suppression efficiency for this Pa-based COP is reported for the first time. This study demonstrates the potential use of MCOP as a photothermal agent for photothermal therapy (PTT) and also provides an alternative route to fabricate nano-sized MCOPs. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Controlled and tunable polymer particles' production using a single microfluidic device

Science.gov (United States)

Amoyav, Benzion; Benny, Ofra

2018-04-01

Microfluidics technology offers a new platform to control liquids under flow in small volumes. The advantage of using small-scale reactions for droplet generation along with the capacity to control the preparation parameters, making microfluidic chips an attractive technology for optimizing encapsulation formulations. However, one of the drawback in this methodology is the ability to obtain a wide range of droplet sizes, from sub-micron to microns using a single chip design. In fact, typically, droplet chips are used for micron-dimension particles, while nanoparticles' synthesis requires complex chips design (i.e., microreactors and staggered herringbone micromixer). Here, we introduce the development of a highly tunable and controlled encapsulation technique, using two polymer compositions, for generating particles ranging from microns to nano-size using the same simple single microfluidic chip design. Poly(lactic-co-glycolic acid) (PLGA 50:50) or PLGA/polyethylene glycol polymeric particles were prepared with focused-flow chip, yielding monodisperse particle batches. We show that by varying flow rate, solvent, surfactant and polymer composition, we were able to optimize particles' size and decrease polydispersity index, using simple chip designs with no further related adjustments or costs. Utilizing this platform, which offers tight tuning of particle properties, could offer an important tool for formulation development and can potentially pave the way towards a better precision nanomedicine.

Toxicity of inhaled 239PuO2 in Beagle dogs. A. Monodisperse 0.75 μm AD particles. B. Monodisperse 1.5 μm AD particles. C. Monodisperse 3.0 μm AD particles. II

International Nuclear Information System (INIS)

Muggenburg, B.A.; Guilmette, R.A.; Hahn, F.F.; McClellan, R.O.; Mauderly, J.L.; Mewhinney, J.A.; Pickrell, J.A.; Boecker, B.B.

1978-01-01

Studies on the metabolism, dosimetry and biological effects of inhaled particles of 239 PuO 2 have been initiated in Beagle dogs. To obtain information on the relative importance of homogeneity of radiation doses to the lung, dogs have been exposed to particles of monodisperse aerosols (sigma/sub g/ 239 PuO 2 ; 40 dogs to the 0.75 μm AD particles, 72 dogs to the 1.5 μm AD particles and 60 dogs to the 3.0 μm AD particles. The exposures have resulted in graded ILB's, which range from 0.0002 to 2.6 μCi/kg body weight. Twenty-nine dogs were exposed to the aerosol diluent and serve as controls. Five dogs have died 336 to 561 days after exposure in the 1.5 μm AD study. Four dogs have died 116 to 589 days after exposure in the 3.0 μm AD study. These dogs had radiation pneumonitis and pulmonary fibrosis at death. The remaining dogs have survived up to 634 days after exposure. It is anticipated that the other dogs planned for these studies will be exposed over the next 12 months

Dynamics of polyelectrolyte adsorption and colloidal flocculation upon mixing studied using mono-dispersed polystyrene latex particles

NARCIS (Netherlands)

Feng, Lili; Cohen Stuart, Martien; Adachi, Yasuhisa

2015-01-01

The dynamic behavior of polyelectrolytes just after their encounter with the surface of bare colloidal particles is analyzed, using the flocculation properties of mono-dispersed polystyrene latex (PSL) particles. Applying a Standardized Colloid Mixing (SCM) approach, effects of ionic strength and

Toxicity of inhaled 239PuO2 in Beagle dogs. A. Monodisperse 0.75 μm AMAD particles. B. Monodisperse 1.5 μm AMAD particles. C. Monodisperse 3.0 μm AMAD particles. V

International Nuclear Information System (INIS)

Muggenburg, B.A.; Guilmette, R.A.; Hahn, F.F.; Boecker, B.B.; McClellan, R.O.; Mauderly, J.L.; Pickrell, J.A.

1982-01-01

Studies on the metabolism, dosimetry and biological effects of inhaled particles of 239 PuO 2 in Beagle dogs are in progress. To obtain information on the relative importance of homogeneity versus nonhomogeneity of radiation doses to the lung, dogs have been exposed to monodisperse aerosols of 239 PuO 2 of 0.75, 1.5 or 3.0 μm activity median aerodynamic diameter (AMAD). The exposures have resulted in graded initial lung burdens ranging from 0.0002 to 2.6 μCi 239 Pu per kilogram body weight. Other dogs were exposed to the aerosol diluent to serve as controls. Ten dogs have died in the study with 0.75 μm AMAD particles, 40 dogs have died in the study with 1.5 μm AMAD particles and 35 dogs have died in the study with 3.0 μm AMAD particles of 239 PuO 2 . Dogs have died with radiation pneumonitis and pulmonary fibrosis and carcinomas of the lung. The remaining dogs have survived up to 2100 days after inhalation exposure and are being observed for the remainder of their life span

Polymer nanocomposites: polymer and particle dynamics

KAUST Repository

Kim, Daniel

2012-01-01

Polymer nanocomposites containing nanoparticles smaller than the random coil size of their host polymer chains are known to exhibit unique properties, such as lower viscosity and glass transition temperature relative to the neat polymer melt. It has been hypothesized that these unusual properties result from fast diffusion of the nanostructures in the host polymer, which facilitates polymer chain relaxation by constraint release and other processes. In this study, the effects of addition of sterically stabilized inorganic nanoparticles to entangled cis-1,4-polyisoprene and polydimethylsiloxane on the overall rheology of nanocomposites are discussed. In addition, insights about the relaxation of the host polymer chains and transport properties of nanoparticles in entangled polymer nanocomposites are presented. The nanoparticles are found to act as effective plasticizers for their entangled linear hosts, and below a critical, chemistry and molecular-weight dependent particle volume fraction, lead to reduced viscosity, glass transition temperature, number of entanglements, and polymer relaxation time. We also find that the particle motions in the polymer host are hyperdiffusive and at the nanoparticle length scale, the polymer host acts like a simple, ideal fluid and the composites\\' viscosity rises with increasing particle concentration. © 2012 The Royal Society of Chemistry.

Repetitive heterocoagulation of oppositely charged particles for enhancement of magnetic nanoparticle loading into monodisperse silica particles.

Science.gov (United States)

Matsumoto, Hideki; Nagao, Daisuke; Konno, Mikio

2010-03-16

Oppositely charged particles were repetitively heterocoagulated to fabricate highly monodisperse magnetic silica particles with high loading of magnetic nanoparticles. Positively charged magnetic nanoparticles prepared by surface modification with N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride (TSA) were used to heterocoagulate with silica particles under basic conditions to give rise to negative silica surface charge and prevent the oxidation of the magnetic nanoparticles. The resultant particles of silica core homogeneously coated with the magnetic nanoparticles were further coated with thin silica layer with sodium silicate in order to enhance colloidal stability and avoid desorption of the magnetic nanoparticles from the silica cores. Five repetitions of the heterocoagulation and the silica coating could increase saturation magnetization of the magnetic silica particles to 27.7 emu/g, keeping the coefficient of variation of particle sizes (C(V)) less than 6.5%. Highly homogeneous loading of the magnetic component was confirmed by measuring Fe-to-Si atomic ratios of individual particles with energy dispersive X-ray spectroscopy.

Facile preparation and visible light photocatalytic activity of CdIn2S4 monodispersed spherical particles

International Nuclear Information System (INIS)

Mu Jin; Wei Qinglian; Yao Pingping; Zhao Xueling; Kang Shizhao; Li Xiangqing

2012-01-01

Highlights: ► CdIn 2 S 4 monodispersed spherical particles were prepared by a soft solution method. ► Mercaptoacetic acid was used as capping agent to hinder the fast crystal growth. ► Thioacetamide as sulfur source resulted in the slow growth of particles. ► CdIn 2 S 4 spheres showed high visible light photocatalytic activity. - Abstract: We developed a facile method to prepare CdIn 2 S 4 monodispersed spherical particles by using mercaptoacetic acid as capping agent and thioacetamide as sulfur source. The results indicated that the size and morphology of CdIn 2 S 4 particles were related to reaction time. The CdIn 2 S 4 spherical particles with an average size of about 236 nm and a narrow size distribution were formed after reacting for 7 h. The photocatalytic activity of as-synthesized CdIn 2 S 4 spherical particles was evaluated by the photocatalytic degradation of methyl orange under visible light illumination. The results showed that the photocatalytic activity increased with prolonging reaction time in the preparation of CdIn 2 S 4 spherical particles. The CdIn 2 S 4 spherical particles prepared after reacting for 7 h exhibited a 98% degradation efficiency of methyl orange after 15 min visible light irradiation.

Transmission and fractionation of micro-sized particle suspensions

NARCIS (Netherlands)

Brans, G.B.P.W.; Dinther, van A.M.C.; Odum, B.; Schroën, C.G.P.H.; Boom, R.M.

2007-01-01

In processes aimed at the fractionation of a multi-component feed stream, transmission of particles through the membrane is at least as important as retention of larger particles. In this paper, we describe the mechanisms of transmission of mono-disperse latex particles through a polymer membrane.

Toxicity of inhaled 239PuO2 in Beagle dogs: A. Monodisperse 0.75-μm AMAD particles. B. Monodisperse 1.5-μm AMAD particles. C. Monodisperse 3.0--μm AMAD particles. XI

International Nuclear Information System (INIS)

Muggenburg, B.A.; Guilmette, R.A.; Hahn, F.F.; Boecker, B.B.; McClellan, R.O.

1988-01-01

Beagle dogs were exposed to monodisperse aerosols of 239 PuO 2 of 0.75, 1.5, or 30 μm activity median aerodynamic diameter (AMAD) to obtain information on the relative importance of homogeneity of alpha irradiation doses to the lung in producing biological effects. The dogs' initial pulmonary burdens (IPB) ranged from 0.0002-2.0 μCi (0.0074 to 74 kBq) 239 Pu/kg of body mass. Thirty-six dogs were exposed to the aerosol diluent as controls. Forty-two of 48 dogs exposed to 0.75 μm AMAD particles have died; 67 of 96 have died in the study involving 1.5 μm AMAD particles; and 62 of 72 have died in the study involving the 3.0 μm AMAD particles. Seven of 36 control dogs have died. Most dogs exposed to 239 Pu that have failed to survive have died with radiation pneumonitis and fibrosis and/or lung cancer. Surviving dogs have lived up to 4300 days after exposure. The data obtained to date indicate that the degree of uniformity of dose to the lung does not significantly modify the risk of lung cancer. (author)

Interaction of polymer with discotic clay particles

International Nuclear Information System (INIS)

Auvray, L.; Lal, J.

1999-01-01

Normally synthetic well defined monodisperse discotic laponite clays are known to form a gel phase at mass concentrations as low as a few percent in distilled water. Hydrosoluble polymer polyethylene oxide was added to this intriguing clay system, it was observed that it either prevents gelation or slows it down extremely depending on the polymer weight, concentration or the laponite concentration. Small Angle Neutron scattering (SANS) was used to study these systems because only by isotopic labeling can the structure of the adsorbed polymer layers be determined. The contrast variation technique is specifically used to determine separately the different partial structure factors of the clay and polymer. In this way the signal of the adsorbed chains is separated from the signal of the free chains in the dilute regime. Attempts have also been made to characterize the structure in the concentrated regime of laponite with polymer

Force chains in monodisperse spherical particle assemblies: Three-dimensional measurements using neutrons

Science.gov (United States)

Wensrich, C. M.; Kisi, E. H.; Luzin, V.; Garbe, U.; Kirstein, O.; Smith, A. L.; Zhang, J. F.

2014-10-01

The full triaxial stress state within individual particles in a monodisperse spherical granular assembly has been measured. This was made possible by neutron imaging and computed tomography combined with neutron diffraction strain measurement techniques and associated stress reconstruction. The assembly in question consists of 549 precision steel ball bearings under an applied axial load of 85 MPa in a cylindrical die. Clear evidence of force chains was observed in terms of both the shape of the probability distribution function for normal stresses and the network formed by highly loaded particles. An extensive analysis of the source and magnitude of uncertainty in these measurements is also presented.

A novel approach for preparation of micrometer-sized, monodisperse dimple and hemispherical polystyrene particles.

Science.gov (United States)

Tanaka, Takuya; Komatsu, Yoshifumi; Fujibayashi, Teruhisa; Minami, Hideto; Okubo, Masayoshi

2010-03-16

Micrometer-sized, monodisperse dimple and hemispherical polystyrene (PS) particles were successfully prepared by heating (55-70 degrees C) of spherical PS particles dispersed in methanol/water media (40/60 to 80/20, w/w) in the presence of decane droplets, and subsequent cooling down to room temperature. Decane was absorbed by the PS particles during the heating process. Decane-absorbed PS particles phase-separated into PS and decane phases in the inside during the cooling process, and eventually dimple and/or hemispherical particles were formed by removal of the decane phase from phase-separated PS/decane particles by evaporation. The size of the dimple, which is determined by the volume of decane phase-separated from decane-absorbed PS particles during the cooling process, increased with increases in the heating temperature and the methanol content.

Study on Soap-free P(MMA-EA-AA/MAA) Latex Particles With Narrow Size Distribution

Institute of Scientific and Technical Information of China (English)

K. Kang; C. Y. Kan; Y. Du; D. S. Liu

2005-01-01

@@ 1Introduction In the past decades, more and more studies have been focused on the synthesis of monodisperse particles with different diameter by special polymerization technique. In 1980' s, Ugelstad, et al[1] invented two-step swelling method to prepare monodisperse microsphere with large size more than 1 μm. In the following decade, Okubo and his coworkers[2] synthesized monodisperse crosslinked polymer particles above 3 μm using one-step dynamic swelling method. New method has been developed to produce particles more than 50 μm in diameter with a standard deviation of less than 2%[3]. Up to now, most of the monodisperse particles were usually prepared by polymerization of St in the presence of surfactants. In this presentation, sub-micro sized P (MMA-EA-AA/MAA) particles with narrow size distribution were prepared by seeded emulsion polymerization in the absence of any surfactant materials.

The effects of surface-charged submicron polystyrene particles on the structure and performance of PSF forward osmosis membrane

Science.gov (United States)

Zuo, Hao-Ran; Fu, Jia-Bei; Cao, Gui-Ping; Hu, Nian; Lu, Hui; Liu, Hui-Qing; Chen, Peng-Peng; Yu, Jie

2018-04-01

Monodisperse surface-charged submicron polystyrene particles were designed, synthesized, and blended into polysulfone (PSF) support layer to prepare forward osmosis (FO) membrane with high performance. The membrane incorporated with particles were characterized with respect to morphology, porosity, and internal osmotic pressure (IOP). Results showed that the polymer particles not only increased the hydrophilicity and porosity of support layer, but also generated considerable IOP, which helped markedly decreasing the structure parameter from 1550 to 670 μm. The measured mass transfer parameters further confirmed the beneficial effects of the surface-charged submicron polymer particles on the performance of FO membrane. For instance, the water permeability coefficient (5.37 L m-2 h-1 bar-1) and water flux (49.7 L m-2 h-1) of the FO membrane incorporated with 5 wt% particles were almost twice as much as that of FO membrane without incorporation. This study suggests that monodisperse surface-charged submicron polymer particles are potential modifiers for improving the performance of FO membranes.

The Generation And Properties Of Solid Monodisperse Aerosols Of ...

African Journals Online (AJOL)

A monodisperse aerosol generator (MAGE) was used to generate calibration or monodisperse aerosols containing stearic acid and carnauba wax. Some of the factors affecting the size of aerosol particles generated with the MAGE were determined. The factors include: temperature of operation of the MAGE, type and purity ...

Galileo symmetries in polymer particle representation

International Nuclear Information System (INIS)

Chiou, D-W

2007-01-01

To illustrate the conceptual problems for the low-energy symmetries in the continuum of spacetime emerging from the discrete quantum geometry, Galileo symmetries are investigated in the polymer particle representation of a non-relativistic particle as a simple toy model. The complete Galileo transformations (translation, rotation and Galileo boost) are naturally defined in the polymer particle Hilbert space and Galileo symmetries are recovered with highly suppressed deviations in the low-energy regime from the underlying polymer particle description

Monodispersed ZIF-8 particles with enhanced performance for CO2 adsorption and heterogeneous catalysis

Science.gov (United States)

Guan, Yebin; Shi, Juanjuan; Xia, Ming; Zhang, Jun; Pang, Zhenfeng; Marchetti, Alessandro; Wang, Xiaohong; Cai, Jingsong; Kong, Xueqian

2017-11-01

Monodispersed zeolitic imidazolate frameworks (ZIFs) were prepared with a simple method using dimethylsulfoxide (DMSO) as solvent. This method yields ZIF-8 nanoparticles with a narrow particle size distribution of 90-110 nm and the dispersion is highly stable against agglomeration. These particles have larger nanosized porosity and enhanced CO2 adsorption capability compared to ZIF-8 prepared with different solvents such as methanol or N, N-dimethyl formamide. Their uniform size and surface chemistry also lead to superior performance in the Knoevenagel condensation reactions. The ZIF-8 nanoparticles possess high thermal stability up to 550 °C and the preparation steps are easy for scaling up which are favorable for industrial applications.

Preparation and magnetic properties of magnetic photonic crystal by using monodisperse polystyrene covered Fe3O4 nanoparticles onto glass substrate

Science.gov (United States)

Azizi, Zahra Sadat; Tehranchi, Mohammad Mehdi; Vakili, Seyed Hamed; Pourmahdian, Saeed

2018-05-01

Engineering approach towards combined photonic band gap properties and magnetic/polymer composite particles, attract considerable attention of researchers due to their unique properties. In this research, two different magnetic particles were prepared by nearly monodisperse polystyrene spheres as bead with two concentrations of Fe3O4 nanoparticles to prepare magnetic photonic crystals (MPCs). The crystal surfaces and particles morphology were investigated employing scanning electron microscopy and transmission electron microscopy. The volume fraction of magnetic material embedded into colloidal spheres and their morphology was found to be a key parameter in the optical and magneto-optical properties of transparent MPC.

Synthesis and characterization of monodisperse, mesoporous, and magnetic sub-micron particles doped with a near-infrared fluorescent dye

International Nuclear Information System (INIS)

Le Guevel, Xavier; Nooney, Robert; McDonagh, Colette; MacCraith, Brian D.

2011-01-01

Recently, multifunctional silica nanoparticles have been investigated extensively for their potential use in biomedical applications. We have prepared sub-micron monodisperse and stable multifunctional mesoporous silica particles with a high level of magnetization and fluorescence in the near infrared region using an one-pot synthesis technique. Commercial magnetite nanocrystals and a conjugated-NIR-dye were incorporated inside the particles during the silica condensation reaction. The particles were then coated with polyethyleneglycol to stop aggregation. X-ray diffraction, N 2 adsorption analysis, TEM, fluorescence and absorbance measurements were used to structurally characterize the particles. These mesoporous silica spheres have a large surface area (1978 m 2 /g) with 3.40 nm pore diameter and a high fluorescence in the near infrared region at λ=700 nm. To explore the potential of these particles for drug delivery applications, the pore accessibility to hydrophobic drugs was simulated by successfully trapping a hydrophobic ruthenium dye complex inside the particle with an estimated concentration of 3 wt%. Fluorescence imaging confirmed the presence of both NIR dye and the post-grafted ruthenium dye complex inside the particles. These particles moved at approximately 150 μm/s under the influence of a magnetic field, hence demonstrating the multifunctionality and potential for biomedical applications in targeting and imaging. - Graphical Abstract: Hydrophobic fluorescent Ruthenium complex has been loaded into the mesopores as a surrogate drug to simulate drug delivery and to enhance the multifunctionality of the magnetic NIR emitting particles. Highlights: → Monodisperse magnetic mesoporous silica particles emitting in the near infrared region are obtained in one-pot synthesis. → We prove the capacity of such particles to uptake hydrophobic dye to mimic drug loading. → Loaded fluorescent particles can be moved under a magnetic field in a microfluidic

Monodisperse, molecularly imprinted polymers for creatinine by modified precipitation polymerization and their applications to creatinine assays for human serum and urine.

Science.gov (United States)

Miura, Chitose; Funaya, Noriko; Matsunaga, Hisami; Haginaka, Jun

2013-11-01

Molecularly imprinted polymers (MIPs) for creatinine were prepared by modified precipitation polymerization using methacrylic acid as a functional monomer and divinylbenzene as a crosslinker. The prepared MIPs were monodispersed with a narrow particle size distribution. Binding experiments and Scatchard analyses revealed that two classes of binding sites, high- and low-affinity sites, were formed on the MIPs. The retention and molecular-recognition properties of the MIPs were evaluated by hydrophilic interaction chromatography using a mixture of ammonium acetate buffer and acetonitrile as a mobile phase. With an increase of acetonitrile content, the retention factor of creatinine was increased on the MIP. In addition to shape recognition, hydrophilic interactions seemed to enhance the recognition of creatinine on the MIP. The MIPs' molecular-recognition ability was specific for creatinine; the structurally related compounds such as hydantoin, 1-methylhydantoin, 2-pyrrolidone, N-hydroxysuccinimide and creatine were not recognized. Furthermore, the creatinine concentrations in human serum and urine were successfully determined by direct injection of the deproteinized serum and diluted urine samples onto the MIP. Copyright © 2013 Elsevier B.V. All rights reserved.

Polymer-Particle Nanocomposites: Size and Dispersion Effects

Science.gov (United States)

Moll, Joseph

Polymer-particle nanocomposites are used in industrial processes to enhance a broad range of material properties (e.g. mechanical, optical, electrical and gas permeability properties). This dissertation will focus on explanation and quantification of mechanical property improvements upon the addition of nanoparticles to polymeric materials. Nanoparticles, as enhancers of mechanical properties, are ubiquitous in synthetic and natural materials (e.g. automobile tires, packaging, bone), however, to date, there is no thorough understanding of the mechanism of their action. In this dissertation, silica (SiO2) nanoparticles, both bare and grafted with polystyrene (PS), are studied in polymeric matrices. Several variables of interest are considered, including particle dispersion state, particle size, length and density of grafted polymer chains, and volume fraction of SiO2. Polymer grafted nanoparticles behave akin to block copolymers, and this is critically leveraged to systematically vary nanoparticle dispersion and examine its role on the mechanical reinforcement in polymer based nanocomposites in the melt state. Rheology unequivocally shows that reinforcement is maximized by the formation of a transient, but long-lived, percolating polymer-particle network with the particles serving as the network junctions. The effects of dispersion and weight fraction of filler on nanocomposite mechanical properties are also studied in a bare particle system. Due to the interest in directional properties for many different materials, different means of inducing directional ordering of particle structures are also studied. Using a combination of electron microscopy and x-ray scattering, it is shown that shearing anisotropic NP assemblies (sheets or strings) causes them to orient, one in front of the other, into macroscopic two-dimensional structures along the flow direction. In contrast, no such flow-induced ordering occurs for well dispersed NPs or spherical NP aggregates! This work

Template synthesis of highly crystalline and monodisperse iron oxide pigments of nanosize

International Nuclear Information System (INIS)

Sreeram, Kalarical Janardhanan; Indumathy, Ramasamy; Rajaram, Ananthanarayanan; Nair, Balachandran Unni; Ramasami, Thirumalachari

2006-01-01

Synthesis of highly crystalline and monodisperse iron oxide nanoparticles is reported. The separation of Fe centers through site-specific binding to a polysaccharide-alginate matrix enables the generation of particles with a monodisperse or narrow size distribution character, resulting in transparent pigments. Site-specific interactions coupled with gel like character of alginate is proposed as the mechanism behind generation of lower particle sizes. Alginate-Fe complexes developed were subjected to heat treatment to provide for crystalline character and development of hematite (α-Fe 2 O 3 ). Conditions most ideal for achieving monodispersity and lower sizes have been optimized and confirmed through microscopic and photon correlation spectroscopic measurements

Preparation of size-tunable, highly monodisperse PVP-protected Pt-nanoparticles by seed-mediated growth

International Nuclear Information System (INIS)

Koebel, Matthias M.; Jones, Louis C.; Somorjai, Gabor A.

2008-01-01

We demonstrate a preparative method which produces highly monodisperse Pt-nanoparticles of tunable size without the external addition of seed particles. Hexachloroplatinic acid is dosed slowly to an ethylene glycol solution at 120 o C and reduced in the presence of a stabilizing polymer poly-N-vinylpyrrolidone (PVP). Slow addition of the Pt-salt will first lead to the formation of nuclei (seeds) which then grow further to produce larger particles of any desired size between 3 and 8 nm. The amount of added hexachloroplatinic acid precursor controls the size of the final nanoparticle product. TEM was used to determine size and morphology and to confirm the crystalline nature of the nanoparticles. Good reproducibility of the technique was demonstrated. Above 7 nm, the particle shape and morphology changes suddenly indicating a change in the deposition selectivity of the Pt-precursor from (100) towards (111) crystal faces and breaking up of larger particles into smaller entities.

Facile and Scalable Synthesis of Monodispersed Spherical Capsules with a Mesoporous Shell

KAUST Repository

Qi, Genggeng

2010-05-11

Monodispersed HMSs with tunable particle size and shell thickness were successfully synthesized using relatively concentrated polystyrene latex templates and a silica precursor in a weakly basic ethanol/water mixture. The particle size of the capsules can vary from 100 nm to micrometers. These highly engineered monodispersed capsules synthesized by a facile and scalable process may find applications in drug delivery, catalysis, separationm or as biological and chemical microreactors. © 2010 American Chemical Society.

Interphase and particle dispersion correlations in polymer nanocomposites

Science.gov (United States)

Senses, Erkan

Particle dispersion in polymer matrices is a major parameter governing the mechanical performance of polymer nanocomposites. Controlling particle dispersion and understanding aging of composites under large shear and temperature variations determine the processing conditions and lifetime of composites which are very important for diverse applications in biomedicine, highly reinforced materials and more importantly for the polymer composites with adaptive mechanical responses. This thesis investigates the role of interphase layers between particles and polymer matrices in two bulk systems where particle dispersion is altered upon deformation in repulsive composites, and good-dispersion of particles is retained after multiple oscillatory shearing and aging cycles in attractive composites. We demonstrate that chain desorption and re-adsorption processes in attractive composites under shear can effectively enhance the bulk microscopic mechanical properties, and long chains of adsorbed layers lead to a denser entangled interphase layer. We further designed experiments where particles are physically adsorbed with bimodal lengths of homopolymer chains to underpin the entanglement effect in interphases. Bimodal adsorbed chains are shown to improve the interfacial strength and used to modulate the elastic properties of composites without changing the particle loading, dispersion state or polymer conformation. Finally, the role of dynamic asymmetry (different mobilities in polymer blends) and chemical heterogeneity in the interphase layer are explored in systems of poly(methyl methacrylate) adsorbed silica nanoparticles dispersed in poly(ethylene oxide) matrix. Such nanocomposites are shown to exhibit unique thermal-stiffening behavior at temperatures above glass transitions of both polymers. These interesting findings suggest that the mobility of the surface-bound polymer is essential for reinforcement in polymer nanocomposites, contrary to existing glassy layer theories

Polymer-Particle Pressure-Sensitive Paint with High Photostability

Directory of Open Access Journals (Sweden)

Yu Matsuda

2016-04-01

Full Text Available We propose a novel fast-responding and paintable pressure-sensitive paint (PSP based on polymer particles, i.e. polymer-particle (pp-PSP. As a fast-responding PSP, polymer-ceramic (PC-PSP is widely studied. Since PC-PSP generally consists of titanium (IV oxide (TiO2 particles, a large reduction in the luminescent intensity will occur due to the photocatalytic action of TiO2. We propose the usage of polymer particles instead of TiO2 particles to prevent the reduction in the luminescent intensity. Here, we fabricate pp-PSP based on the polystyrene particle with a diameter of 1 μm, and investigate the pressure- and temperature-sensitives, the response time, and the photostability. The performances of pp-PSP are compared with those of PC-PSP, indicating the high photostability with the other characteristics comparable to PC-PSP.

A general approach for monodisperse colloidal perovskites, Chemistry of Materials

NARCIS (Netherlands)

Demirors, A.F.; Imhof, A.

2009-01-01

We describe a novel general method for synthesizing monodisperse colloidal perovskite particles at room temperature by postsynthesis addition of metal hydroxides to amorphous titania colloids. In previous work, we used titania particles to synthesize homogenously mixed silica-titania composite

Microfluidic Production of Alginate Hydrogel Particles for Antibody Encapsulation and Release.

Science.gov (United States)

Mazutis, Linas; Vasiliauskas, Remigijus; Weitz, David A

2015-12-01

Owing to their biocompatibility and reduced side effects, natural polymers represent an attractive choice for producing drug delivery systems. Despite few successful examples, however, the production of monodisperse biopolymer-based particles is often hindered by high viscosity of polymer fluids. In this work, we present a microfluidic approach for production of alginate-based particles carrying encapsulated antibodies. We use a triple-flow micro-device to induce hydrogel formation inside droplets before their collection off-chip. The fast mixing and gelation process produced alginate particles with a unique biconcave shape and dimensions of the mammalian cells. We show slow and fast dissolution of particles in different buffers and evaluate antibody release over time. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cluster synthesis of monodisperse rutile-TiO2 nanoparticles and dielectric TiO2-vinylidene fluoride oligomer nanocomposites

International Nuclear Information System (INIS)

Balasubramanian, Balamurugan; Kraemer, Kristin L; Valloppilly, Shah R; Ducharme, Stephen; Sellmyer, David J

2011-01-01

The embedding of oxide nanoparticles in polymer matrices produces a greatly enhanced dielectric response by combining the high dielectric strength and low loss of suitable host polymers with the high electric polarizability of nanoparticles. The fabrication of oxide-polymer nanocomposites with well-controlled distributions of nanoparticles is, however, challenging due to the thermodynamic and kinetic barriers between the polymer matrix and nanoparticle fillers. In the present study, monodisperse TiO 2 nanoparticles having an average particle size of 14.4 nm and predominant rutile phase were produced using a cluster-deposition technique without high-temperature thermal annealing and subsequently coated with uniform vinylidene fluoride oligomer (VDFO) molecules using a thermal evaporation source, prior to deposition as TiO 2 -VDFO nanocomposite films on suitable substrates. The molecular coatings on TiO 2 nanoparticles serve two purposes, namely to prevent the TiO 2 nanoparticles from contacting each other and to couple the nanoparticle polarization to the matrix. Parallel-plate capacitors made of TiO 2 -VDFO nanocomposite film as the dielectric exhibit minimum dielectric dispersion and low dielectric loss. Dielectric measurements also show an enhanced effective dielectric constant in TiO 2 -VDFO nanocomposites as compared to that of pure VDFO. This study demonstrates for the first time a unique electroactive particle coating in the form of a ferroelectric VDFO that has high-temperature stability as compared to conventionally used polymers for fabricating dielectric oxide-polymer nanocomposites.

Experimental mixture design as a tool for the synthesis of antimicrobial selective molecularly imprinted monodisperse microbeads.

Science.gov (United States)

Benito-Peña, Elena; Navarro-Villoslada, Fernando; Carrasco, Sergio; Jockusch, Steffen; Ottaviani, M Francesca; Moreno-Bondi, Maria C

2015-05-27

The effect of the cross-linker on the shape and size of molecular imprinted polymer (MIP) beads prepared by precipitation polymerization has been evaluated using a chemometric approach. Molecularly imprinted microspheres for the selective recognition of fluoroquinolone antimicrobials were prepared in a one-step precipitation polymerization procedure using enrofloxacin (ENR) as the template molecule, methacrylic acid as functional monomer, 2-hydroxyethyl methacrylate as hydrophilic comonomer, and acetonitrile as the porogen. The type and amount of cross-linker, namely ethylene glycol dimethacrylate, divinylbenzene or trimethylolpropane trimethacrylate, to obtain monodispersed MIP spherical beads in the micrometer range was optimized using a simplex lattice design. Particle size and morphology were assessed by scanning electron microscopy, dynamic light scattering, and nitrogen adsorption measurements. Electron paramagnetic resonance spectroscopy in conjunction with a nitroxide as spin probe revealed information about the microviscosity and polarity of the binding sites in imprinted and nonimprinted polymer beads.

Nanoscale morphogenesis of nylon-sputtered plasma polymer particles

Science.gov (United States)

Choukourov, Andrei; Shelemin, Artem; Pleskunov, Pavel; Nikitin, Daniil; Khalakhan, Ivan; Hanuš, Jan

2018-05-01

Sub-micron polymer particles are highly important in various fields including astrophysics, thermonuclear fusion and nanomedicine. Plasma polymerization offers the possibility to produce particles with tailor-made size, crosslink density and chemical composition to meet the requirements of a particular application. However, the mechanism of nucleation and growth of plasma polymer particles as well as diversity of their morphology remain far from being clear. Here, we prepared nitrogen-containing plasma polymer particles by rf magnetron sputtering of nylon in a gas aggregation cluster source with variable length. The method allowed the production of particles with roughly constant chemical composition and number density but with the mean size changing from 80 to 320 nm. Atomic Force Microscopy with super-sharp probes was applied to study the evolution of the particle surface topography as they grow in size. Height–height correlation and power spectral density functions were obtained to quantify the roughness exponent α  =  0.78, the growth exponent β  =  0.35, and the dynamic exponent 1/z  =  0.50. The set of critical exponents indicates that the particle surface evolves in a self-affine mode and the overall particle growth is caused by the accretion of polymer-forming species from the gas phase and not by coagulation. Redistribution of the incoming material over the surface coupled with the inhomogeneous distribution of inner stress is suggested as the main factor that determines the morphogenesis of the plasma polymer particles.

Annealing effect on the structural and optical properties of Cr/α-Cr2O3 monodispersed particles based solar absorbers

International Nuclear Information System (INIS)

Khamlich, S.; McCrindle, R.; Nuru, Z.Y.; Cingo, N.; Maaza, M.

2013-01-01

Graphical abstract: A cost-effective and environmentally friendly green chemical method, the so-called aqueous chemical growth (ACG) method, was used to deposit chromium/alpha-chromium(III) oxide, Cr/α-Cr 2 O 3 , monodispersed particles, for solar absorbers applications. Highlights: ► Cr/α-Cr 2 O 3 have been deposited by the aqueous chemical growth (ACG) method. ► High temperature annealing affects the optical selectivity of the deposited particles. ► Oxygen diffusion to the interface at high temperature results in the oxidization of the substrate. - Abstract: A cost-effective and environmentally friendly green chemical method, the so-called aqueous chemical growth (ACG) method, was used to deposit chromium/alpha-chromium(III) oxide, Cr/α-Cr 2 O 3 , monodispersed particles, for solar absorbers applications. The deposited particles were annealed at various temperatures in a hydrogen atmosphere for 2 h to study the annealing temperature dependence of the structural, chemical and optical properties of the particles grown on tantalum substrates. The deposited Cr/α-Cr 2 O 3 was characterized by X-ray diffraction (XRD), attenuated total reflection (ATR), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and diffuse reflectance UV–vis–NIR spectroscopy. The XRD and ATR analysis indicated that by increasing annealing temperature, the particles crystallinity was improved and Ta 2 O 5 was formed around 600 °C, due to the fast oxygen diffusion from the deposited α-Cr 2 O 3 toward the tantalum substrate. The optical measurements show that samples annealed at 400 and 500 °C exhibit the targeted high absorbing optical characteristics of “Black chrome”, while those annealed below 400 °C and above 500 °C show a significant low absorptivity and high emissivity.

Assembling and properties of the polymer-particle nanostructured materials

Science.gov (United States)

Sheparovych, Roman

Complementary properties of the soft and hard matter explain its common encounter in many natural and manmade applications. A combination of flexible organic macromolecules and hard mineral clusters results in new materials far advantageous than its constituents alone. In this work we study assembling of colloidal nanocrystals and polymers into complex nanostructures. Magnetism, surface wettability and adhesion comprise properties of interest for the obtained nanocomposites. Applying a magnetic field induces a reversible 1D ordering of the magnetically susceptible particles. This property was employed in the fabrication of the permanent chains of magnetite nanocrystals (d=15nm). In the assembling process the aligned particles were bound together using polyelectrolyte macromolecules. The basics of the binding process involved an electrostatic interaction between the positively charged polyelectrolyte and the negative surface of the particles (aqueous environment). Adsorption of the polymer molecules onto several adjacent particles in the aligned 1D aggregate results in the formation of the permanent particulate chains. Positive charges of the adsorbed polyelectrolyte molecules stabilize the dispersion of the obtained nanostructures in water. Magnetization measurements revealed that superparamagnetic nanoparticles, being assembled into 1D ordered structures, attain magnetic coercivity. This effect originates from the magnetostatic interaction between the neighboring magnetite nanocrystals. The preferable dipole alignment of the assembled nanoparticles is directed along the chain axis. Another system studied in this project includes polymer-particle responsive surface coatings. Tethered polymer chains and particles bearing different functionalities change surface properties upon restructuring of the composite layer. When the environment favors polymer swelling (good solvent), the polymer chains segregate to the surface and cover the particles. In the opposite case

Toxicity of inhaled 238PuO2 in beagle dogs. A. Monodisperse 1.5 μm 238PuO2. B. Monodisperse 3.0 μm 238PuO2 particles. III

International Nuclear Information System (INIS)

Lustgarten, C.S.; Mewhinney, J.A.; Hobbs, C.H.; Halliwell, W.H.; Jones, R.K.; Mauderly, J.L.; McClellan, R.O.; Mo, T.; Pickrell, J.A.

1976-01-01

To obtain essential information on the importance of the homogeneity or non-homogeneity of the radiation dose to lung (the hot particle question), Beagle dogs have been exposed to monodisperse aerosols (sigma/sub g/ 238 PuO 2 of either 1.5 μm or 3.0 μm aerodynamic diameter (AD). By using monodisperse particles of these two sizes, the average dose to lung is held constant for a given initial lung burden, but the local alpha dose around the two sizes of particles varies by a factor of about ten. All exposures have been completed with 72 days exposed to each of the two particle sizes of 238 PuO 2 (total of 144 dogs) resulting in graded initial lung burdens which range from .005 to 2.2 μCi/kg of body weight. Twenty-four dogs exposed to the diluent aerosol are serving as controls. The animals will be studied over their total life span. Two exposed dogs have died from pulmonary injury: Dog 710C (with an initial lung burden of 2.0 μCi/kg) died at 631 days after inhalation of 3.0 μm AD aerosol. The cause of death was radiation pneumonitis and pulmonary fibrosis, Dog 746B (with an initial lung burden of 1.3 μCi/kg) died at 791 days after inhalation of 1.5 μm AD aerosol. Death was attributed to intrapulmonic hemorrhage resulting from a degenerative vasculitis. One control dog (721A) was euthanized at 820 days after exposure due to a meningitis and encephalomalacia that caused a severe central nervous system disorder that made the dog difficult to handle.A leukopenia in exposed dogs to date has occurred earlier and to a greater degree in dogs exposed to 3.0 μm AD particles than in dogs that recevied 1.5 μm AD particles. One hundred forty-two exposed and 23 control dogs are surviving at 175 to 1024 days after exposure

Microfluidic assembly of monodisperse multistage pH-responsive polymer/porous silicon composites for precisely controlled multi-drug delivery.

Science.gov (United States)

Liu, Dongfei; Zhang, Hongbo; Herranz-Blanco, Bárbara; Mäkilä, Ermei; Lehto, Vesa-Pekka; Salonen, Jarno; Hirvonen, Jouni; Santos, Hélder A

2014-05-28

We report an advanced drug delivery platform for combination chemotherapy by concurrently incorporating two different drugs into microcompoistes with ratiometric control over the loading degree. Atorvastatin and celecoxib were selected as model drugs due to their different physicochemical properties and synergetic effect on colorectal cancer prevention and inhibition. To be effective in colorectal cancer prevention and inhibition, the produced microcomposite contained hypromellose acetate succinate, which is insoluble in acidic conditions but highly dissolving at neutral or alkaline pH conditions. Taking advantage of the large pore volume of porous silicon (PSi), atorvastatin was firstly loaded into the PSi matrix, and then encapsulated into the pH-responsive polymer microparticles containing celecoxib by microfluidics in order to obtain multi-drug loaded polymer/PSi microcomposites. The prepared microcomposites showed monodisperse size distribution, multistage pH-response, precise ratiometric controlled loading degree towards the simultaneously loaded drug molecules, and tailored release kinetics of the loaded cargos. This attractive microcomposite platform protects the payloads from being released at low pH-values, and enhances their release at higher pH-values, which can be further used for colon cancer prevention and treatment. Overall, the pH-responsive polymer/PSi-based microcomposite can be used as a universal platform for the delivery of different drug molecules for combination therapy. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interaction of energetic particles with polymer surfaces: surface morphology development and sputtered polymer-fragment ion analysis

International Nuclear Information System (INIS)

Michael, R.S.

1987-01-01

The core of this thesis is based on a series of papers that have been published or will soon be published in which the various processes taking place in the energetic particle-polymer surface interaction scene is investigated. Results presented show different developments on polymer surfaces when compared to the vast experimental data on energetic particle-metal surface interactions. The surface morphology development depends on the physical characteristics of the polymer. Sputtering yields of fluoropolymers were several orders higher than the sputtering yields of aliphatic and aromatic polymers. Depending on the chemical nature of the polymer, the surface morphology development was dependent upon the extent of radiation-damage accumulation. Fast Atom Bombardment Mass Spectrometry at low and high resolution was applied to the characterization of sputtered polymer fragment ions. Fragment ions and their intensities were used to identify polymer samples, observe radiation damage accumulation and probe polymer-polymer interface of a polymer-polymer sandwich structure. A model was proposed which attempts to explain the nature of processes involved in the energetic particle-polymer surface interaction region

Effect of nanosilica particles on polypropylene polymer modified asphalt mixture performance

Directory of Open Access Journals (Sweden)

Nura Bala

2018-06-01

Full Text Available The current study was conducted to investigate the effect of nanosilica particles on the performance characteristics of polymer modified asphalt binders. In this study, control 80/100 binder were modified with polypropylene polymer and nanosilica particles at concentration of 0%–4%. Both nanosilica particles and polypropylene polymer were added by weight of total bitumen content. The asphalt performance tests flexural four point beam fatigue test, indirect tensile strength, indirect tensile stiffness modulus and draindown tests are conducted to evaluate the effect of nanosilica particles. The results of the study shows that nanosilica particles improves the fatigue properties of polypropylene polymer modified binder. This indicates that nanosilica particles have significant effect on improving the performance properties of polymer modified binders. Also, the result reveals that thermoplastic polymer polypropylene with nanosilica particles when used as bitumen modifiers improve the performance and durability of asphalt mixtures. Keywords: Polypropylene, Fatigue cracking, Stiffness modulus, Modified asphalt, Draindown

Retention studies in rats exposed to monodisperse aerosols of /sup 198/Au labeled carnauba wax particles

Energy Technology Data Exchange (ETDEWEB)

Tarroni, G.; Bassi, P.; Belvisi, M.B.; Bianco, A.

1981-01-01

Rats were exposed to monodisperse carnauba wax aerosols labeled with colloidal /sup 198/Au and the retained activity was followed both in vivo and in the lungs of serially sacrified animals. In vitro and in vivo tests have shown low leaching rates of the label. The deposited activity could then be followed without correction for particle solubility. The activity in vivo shows a three-exponential decay, characterized by half-times of a few hours, one day, and one month corresponding to the clearance of the material deposited respectively in the extrathoracic airways, in the tracheo-bronchial, and in the alveolar regions. A correlation was found between long term cleared activity and particle size but no correlation was found between particle size and clearance half times in the size range investigated. Statistical evaluation of the activity vs time in vivo and in excised lungs has shown that the long term retained activity pertains to the alveolar region and, if a large number of animals is not used, more accurate data of pulmonary clearance can be obtained by in vivo measurements than by serial sacrifices.

Near-infrared (NIR) emitting conjugated polymers for biomedical applications (Presentation Recording)

Science.gov (United States)

Repenko, Tatjana; Kuehne, Alexander J. C.

2015-10-01

Fluorescent biomedical markers of today such as dye-infiltrated colloids, microgels and quantum dots suffer from fast bleaching, lack surface functionality (for targets or pharmaceutical agents) and potentially leach heavy metals in case of quantum dots (e.g. Cd). By contrast, conjugated polymer particles are non-cytotoxic, exhibit reduced bleaching, as the entire particle consists of fluorophore, they are hydrophobic and show high quantum yields. Consequently, conjugated polymer particles represent ideal materials for biological applications and imaging. However currently, conjugated polymer particles for biomedical imaging usually lack near-infrared (NIR) emission and are polydisperse. Fluorescent agents with emission in the NIR spectrum are interesting for biomedical applications due to their low photo-damage towards biological species and the ability of NIR radiation to penetrate deep into biological tissue.. I will present the development and synthesis of new conjugated polymers particles with fluorescence in the NIR spectral region for bio-imaging and clinical diagnosis. The particle synthesis proceeds in a one-step Pd or Ni-catalyzed dispersion polymerization of functional NIR emitters. The resulting monodisperse conjugated polymer particles are obtained as a dispersion in a non-hazardous solvent. Different sizes in the sub-micrometer range with a narrow size distribution can be produced. Furthermore biological recognition motifs can be easily attached to the conjugated polymers via thiol-yne click-chemistry providing specific tumor targeting without quenching of the fluorescence. References [1] Kuehne AJC, Gather MC, Sprakel J., Nature Commun. 2012, 3, 1088. [2] Repenko T, Fokong S, De Laporte L, Go D, Kiessling F, Lammers T, Kuehne AJC.,Chem Commun 2015, accepted.

Radiosynthesis and in vitro evaluation of the polystyrene particles as a promising probe in biomedical sciences

International Nuclear Information System (INIS)

Chen Jianmin; Tan Mingguang; Wu Yuanfang; Zhang Guilin; Li Yan

2005-01-01

Polystyrene particles with precise monodisperse particle size distributions ranging from 20nm to 90μm is now commercially available and it has very useful and versatile applications in many life sciences research fields. A simple direct labeling method was used to synthesis the iodinated ultrafine polystyrene particles. The assay of X-ray photoelectron spectroscopy(XPS) as well as Fourier Transform Infrared Spectroscopy (FTIR) indicated the formation of stable covalent bond to aryl group of the polymer particles. The purified radiosynthesis product was incubated with serum of rat, and then evaluated by in vitro stability test. The result showed that radioiodinated ultrafine polystyrene particles were largely unmetablized at 2 hours post-exposure, indicating the potential useful application of this widely used polymer particles as a promising probe in biomedical and pharmaceutical sciences.

Characterization of a monodispersed aerosol exposure system for beagle dogs

International Nuclear Information System (INIS)

Cannon, W.C.; Herring, J.P.; Craig, D.K.

1978-01-01

A monodispersed aerosol exposure system for dogs is described and data are presented on aerosol depositions in the exposure system which could affect the aerosol presented to the animals by reducing the concentration and changing the particle size distribution

Lock and Key Colloids through Polymerization-Induced Buckling of Monodispersed Silicon Oil Droplets

Science.gov (United States)

Sacanna, Stefano; Irvine, William T. M.; Chaikin, Paul M.; Pine, David J.

2010-03-01

Colloidal particles can spontaneously associate into larger structured aggregates when driven by selective and directional interactions. Colloidal organization can be programmed by engineering shapes and interactions of basic building blocks in a manner similar to molecular self-assembly. Examples of successful strategies that allow non-trivial assembly of particles include template-directed patterning, capillary forces and, most commonly, the functionalization of the particle surfaces with ``sticky patches'' of biological or synthetic molecules. The level of complexity of the realizable assemblies, increases when particles with well defined shape anisotropies are used. In particular depletion forces and specific surface treatments in combination with non spherical particles have proven to be powerful tools to self-assembly complex microstructures. We describe a simple, high yield, synthetic pathway to fabricate monodisperse hybrid silica spheres with well defined cavities. Because the particle morphologies are reproducible and tunable with precision, the resulting particles can be used as basic building blocks in the assembly of larger monodisperse clusters. This is demonstrated using depletion to drive the self-assembly.

Monodisperse, submicrometer-scale platinum colloidal spheres with high electrocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Zhang, Lixue; Wang, Liang; Guo, Shaojun; Zhai, Junfeng; Dong, Shaojun; Wang, Erkang [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, 130022 Jilin, Changchun (China)

2009-02-15

Monodisperse, submicrometer-scale platinum (Pt) colloidal spheres were prepared through a simple direct chemical reduction of p-phenylenediamine (PPD)-chloroplatinic acid (H{sub 2}PtCl{sub 6}) coordination polymer colloids. It was found that the prepared Pt colloids had the similar size and morphology with their coordination polymer precursors, and the prepared Pt colloids with rough surfaces were three-dimensional (3D) structured assemblies of high-density small Pt nanoparticles. The electrochemical experiments confirmed that the prepared Pt colloids possessed a high electrocatalytic activity towards mainly four-electron reduction of dioxygen to water, making the prepared Pt colloids potential candidates for the efficient cathode material in fuel cells. (author)

Motion of Adsorbed Nano-Particles on Azobenzene Containing Polymer Films

Directory of Open Access Journals (Sweden)

Sarah Loebner

2016-12-01

Full Text Available We demonstrate in situ recorded motion of nano-objects adsorbed on a photosensitive polymer film. The motion is induced by a mass transport of the underlying photoresponsive polymer material occurring during irradiation with interference pattern. The polymer film contains azobenzene molecules that undergo reversible photoisomerization reaction from trans- to cis-conformation. Through a multi-scale chain of physico-chemical processes, this finally results in the macro-deformations of the film due to the changing elastic properties of polymer. The topographical deformation of the polymer surface is sensitive to a local distribution of the electrical field vector that allows for the generation of dynamic changes in the surface topography during irradiation with different light interference patterns. Polymer film deformation together with the motion of the adsorbed nano-particles are recorded using a homemade set-up combining an optical part for the generation of interference patterns and an atomic force microscope for acquiring the surface deformation. The particles undergo either translational or rotational motion. The direction of particle motion is towards the topography minima and opposite to the mass transport within the polymer film. The ability to relocate particles by photo-induced dynamic topography fluctuation offers a way for a non-contact simultaneous manipulation of a large number of adsorbed particles just in air at ambient conditions.

Laboratory evaluation of a vibrating orifice monodisperse aerosol generator

International Nuclear Information System (INIS)

Everitt, N.M.; Snelling, K.W.

1985-02-01

The Berglund-Liu vibrating orifice aerosol generator is capable of producing monodisperse particles in the diameter range 5 to 50 μm. Experiments have been carried out to set up and evaluate such a generator for the preparation of standard liquid (olive oil) and solid (methylene blue) aerosols in the size range 8 to 13 μm. Modifications have been made to the apparatus to improve its performance and increase its particle output. (author)

Solution electrospinning of particle-polymer composite fibres

DEFF Research Database (Denmark)

Christiansen, Lasse; Fojan, Peter

2016-01-01

-scale, is produced. The maximum polymer-silica weight-ratio yielding stable fibres has also been determined. The morphology of the fibres at different weight ratios has been investigated by optical microscopy and scanning electron microscope (SEM). Low aerogel concentrations yield few particles located in polymer...

Room temperature vortex fluidic synthesis of monodispersed amorphous proto-vaterite.

Science.gov (United States)

Peng, Wenhong; Chen, Xianjue; Zhu, Shenmin; Guo, Cuiping; Raston, Colin L

2014-10-11

Monodispersed particles of amorphous calcium carbonate (ACC) 90 to 200 nm in diameter are accessible at room temperature in ethylene glycol and water using a vortex fluidic device (VFD). The ACC material is stable for at least two weeks under ambient conditions.

Development of polymer films by the coalescence of polymer particles in powdered and aqueous polymer-modified mortars

International Nuclear Information System (INIS)

Afridi, M.U.K.; Ohama, Y.; Demura, K.; Iqbal, M.Z.

2003-01-01

This paper evaluates and compares the coalescence of polymer particles (continuous polymer films formation) in powdered polymer-modified mortars (PPMMs) and aqueous polymer-modified mortars (APMMs). Polymer-modified mortars (PMMs) using various redispersible polymer powders (powdered cement modifiers) and polymer dispersions (aqueous cement modifiers) were prepared by varying the polymer-cement ratio (P/C) and were tested for the characterization of polymer films using a scanning electron microscope (SEM) after curing for 28 days. It is concluded from the test results that mortar constituents of unmodified mortar (UMM) are loosely joined with each other due to the absence of polymer films, thus having a structure with comparatively lower mechanical and durability characteristics. By contrast, mortar constituents in PPMMs and APMMs are compactly joined with each other due to the presence of interweaving polymer films, thereby forming a monolithic structure with improved mechanical and durability characteristics. However, the results make obvious the poor coalescence of polymer particles or development of inferior quality polymers films in PPMMs as compared to that observed in APMMs. Moreover, PPMMs show less uniform distribution of polymer films as compared to that in APMMs. Different powdered cement modifiers have different film-forming capabilities. However, such difference is hardly recognized in aqueous cement modifiers. The polymer films in PPMMs and APMMs may acquire different structures. They may appear as mesh-like, thread-like, rugged, dense or fibrous with fine or rough surfaces. Development of coherent polymer films is not well pronounced at a P/C of 5% in PPMMs, whereas sometimes coherent polymer films are observed at a P/C of 5% in APMMs. At a P/C of 10% or more, fully developed, coherent polymer films are observed in both PPMMs and APMMs

Plot of charged nuclear particles in polymers

International Nuclear Information System (INIS)

Gallardo H, J.I.L.

1975-01-01

Experiments were made in order to obtain particle tracks and fission fragments in polymers. To increase the damage the polymer is attacked chemically with a solution of KOH, NaOH or other chemical agent, whose concentration depends of the polymer to be treated, maintaining a constant temperature during the process. To count the tracks which perforate the film, a spark counter with controlled nitrogen atmosphere was constructed. In the experiments which were made in order to detect particles, films of cellulose nitrate known as xylonite, daicel and red paper were used. For the detection of fission products, cellulose triacetate and cellulose polycarbonate films, known as kodacel and kimfol were used. The particle tracks on the treated films were optically counted with a microscope. They had a diameter between 12 and 30 microns, and when the thickness of the film permitted it the tracks consisted in perforations from one to another side of the film. The obtained results have permitted to have the necessary reproducibility for the realization of quantitative analysis of irradiations which can be applied to neutron dosimetry. (author)

Monodisperse microbeads of hypercrosslinked polystyrene for liquid and supercritical fluid chromatography

Science.gov (United States)

Tsyurupa, M. P.; Blinnikova, Z. K.; Il'in, M. M.; Davankov, V. A.; Parenago, O. O.; Pokrovskii, O. I.; Usovich, O. I.

2015-11-01

Monodisperse styrene-divinylbenzene (1 wt %) copolymer microbeads are obtained via the elaborate method of high-productivity precipitation polymerization. The crosslinking of this copolymer with chloromethyl methyl ether in the presence of Friedel-Crafts catalyst yields porous hypercrosslinked polymers with degrees of crosslinking that range from 200 to 500%. Microbead sorbents are shown to be suited for selective stationary phases for high-performance liquid chromatography and supercritical fluid chromatography.

Production of monodisperse respirable aerosols of 241AmO2 and evaluation of in vitro dissolution

International Nuclear Information System (INIS)

Boyd, H.A.; Raabe, O.G.; Peterson, P.K.

1974-01-01

A method is described for production of monodisperse (sigma//sub g/ less than 1.2) particles of 241 AmO 2 for use in inhalation experiments with dogs and rodents. The effects of physical and chemical factors on the production of polydisperse aerosols of 241 AmO 2 were studied and evaluated. The best aerosol was achieved when a suspension of americium hydroxide with 2.5 mg Am/ml at pH = 7.3 was aerosolized and passed through two heating columns in succession, the first at 300 0 C and the second at 1050 0 C. The particles were roughly spherical and had densities near 8 gm/cm 3 ; the aerosol AMAD and sigma/sub g/ were about 1.5 μm and 1.7, respectively. Monodisperse particles were separated and collected with the Lovelace Aerosol Particle Separator (LAPS) and subsequently suspended in deionized water with pH adjusted to 10.2 with NH 3 for nebulization to produce monodisperse aerosols for inhalation exposures. Particles collected on filters during inhalation experiments were used for evaluation of in vitro dissolution rates with two systems and various forms of a lung fluid simulant. The important role of phosphate ions in such dissolution systems was demonstrated, suggesting the potential for the equally important role of free phosphate in retarding dissolution of AmO 2 particles in the lung. (U.S.)

Blocking effect and numerical study of polymer particles dispersion flooding in heterogeneous reservoir

Science.gov (United States)

Zhu, Weiyao; Li, Jianhui; Lou, Yu

2018-02-01

Polymer flooding has become an effective way to improve the sweep efficiency in many oil fields. Many scholars have carried out a lot of researches on the mechanism of polymer flooding. In this paper, the effect of polymer on seepage is analyzed. The blocking effect of polymer particles was studied experimentally, and the residual resistance coefficient (RRF) were used to represent the blocking effect. We also build a mathematical model for heterogeneous concentration distribution of polymer particles. Furthermore, the effects of polymer particles on reservoir permeability, fluid viscosity and relative permeability are considered, and a two-phase flow model of oil and polymer particles is established. In addition, the model was tested in the heterogeneous stratum model, and three influencing factors, such as particle concentration, injection volume and PPD (short for polymer particle dispersion) injection time, were analyzed. Simulation results show that PPD can effectively improve sweep efficiency and especially improve oil recovery of low permeability layer. Oil recovery increases with the increase of particle concentration, but oil recovery increase rate gradually decreases with that. The greater the injected amount of PPD, the greater oil recovery and the smaller oil recovery increase rate. And there is an optimal timing to inject PPD for specific reservoir.

Optimization of a simple technique for preparation of monodisperse poly(lactide-co-glycolide) nanospheres

Energy Technology Data Exchange (ETDEWEB)

Ito, Fuminori, E-mail: fuminoito@spice.ocn.ne.jp [Tokyo Metropolitan University, Department of Applied Chemistry, Graduate School of Urban Environmental Sciences (Japan)

2016-09-15

In this study, we report the optimization of a solvent evaporation technique for preparing monodisperse poly-(lactide-co-glycolide) (PLGA) nanospheres, from a mixture of solvents composed of ethanol and PVA solution. Various experimental conditions were investigated in order to control the particle size and size distribution of the nanospheres. In addition, nanospheres containing rifampicin (RFP, an antituberculosis drug), were prepared using PLGA of various molecular weights, to study the effects of RFP as a model hydrophobic drug. The results showed that a higher micro-homogenizer stirring rate facilitated the preparation of monodisperse PLGA nanospheres with a low coefficient of variation (~20 %), with sizes below 200 nm. Increasing the PLGA concentration from 0.1 to 0.5 g resulted in an increase in the size of the obtained nanospheres from 130 to 174 nm. The molecular weight of PLGA had little effect on the particle sizes and particle size distributions of the nanospheres. However, the drug loading efficiencies of the obtained RFP/PLGA nanospheres decreased when the molecular weight of PLGA was increased. Based on these experiments, an optimized technique was established for the preparation of monodisperse PLGA nanospheres, using the method developed by the authors.Graphical Abstract.

Emulsion Polymerization of Etyl Acrylate: The Effect of Surfactant, Initiator Concentration and PolymerizationTechnique on Particle Size Distribution

Directory of Open Access Journals (Sweden)

Nitri Arinda

2009-04-01

Full Text Available Emulsion polymerization was conducted using ethyl acrylate monomer. Theeffect of sodium lauryl sulfate concentration, ammonium persulfate concentration, the various of polymerizationtechniques and feeding time to the conversion, particle size and its distribution were observed. The purpose of thisresearch is to obtain the optimum condition of ethyl acrylate homopolymer with particle size around 100 nm, to get theparticle size distribution monodisperse and to get solid content value of the experiment closed to its theoretical value.The optimum condition then could be applied in shell polymerization of core-shell polymers. The results of the researchshowed that semicontinuous technique obtained optimum sodium lauryl sulfate concentration at 20 CMC (criticalmicelle concentration and ammonium persulfate concentration is 3%. By using batch technique that the biggestparticle size is 123 nm with conversion 95.8% and monodisperse. The shorter of feeding time the more monomer ofethyl acrylate being polymerized, it is showed by the higher conversion up to 94.4% and the bigger particle size is107.9 nm.

Prediction of elastic properties for polymer-particle nanocomposites exhibiting an interphase

International Nuclear Information System (INIS)

Deng Fei; Van Vliet, Krystyn J

2011-01-01

Particle-polymer nanocomposites often exhibit mechanical properties described poorly by micromechanical models that include only the particle and matrix phases. Existence of an interfacial region between the particle and matrix, or interphase, has been posited and indirectly demonstrated to account for this effect. Here, we present a straightforward analytical approach to estimate effective elastic properties of composites comprising particles encapsulated by an interphase of finite thickness and distinct elastic properties. This explicit solution can treat nanocomposites that comprise either physically isolated nanoparticles or agglomerates of such nanoparticles; the same framework can also treat physically isolated nanoparticle aggregates or agglomerates of such aggregates. We find that the predicted elastic moduli agree with experiments for three types of particle-polymer nanocomposites, and that the predicted interphase thickness and stiffness of carbon black-rubber nanocomposites are consistent with measured values. Finally, we discuss the relative influence of the particle-polymer interphase thickness and stiffness to identify maximum possible changes in the macroscale elastic properties of such materials.

Semi-flexible polymer engendered aggregation/dispersion of fullerene (C60) nano-particles: An atomistic investigation

Science.gov (United States)

Kumar, Sunil; Pattanayek, Sudip K.

2018-06-01

Semi flexible polymer chain has been modeled by choosing various values of persistent length (stiffness). As the polymer chain stiffness increases, the shape of polymer chain changes from globule to extended cigar to toroid like structure during cooling from a high temperature. The aggregation of fullerene nano-particles is found to depend on the morphology of polymer chain. To maximize, the number of polymer bead-nanoparticle contacts, all nano-particle have positioned inside the polymer globule. To minimize, the energy penalty, due to bending of the polymer chain, all nano-particle have positioned on the surface of the polymer's cigar and toroid morphology.

Growth of monodisperse mesoscopic metal-oxide colloids under constant monomer supply

Science.gov (United States)

Nozawa, Koh; Delville, Marie-Hélène; Ushiki, Hideharu; Panizza, Pascal; Delville, Jean-Pierre

2005-07-01

In closed systems, control over the size of monodisperse metal-oxide colloids is generally limited to submicrometric dimensions. To overcome this difficulty, we explore the formation and growth of silica particles under constant monomer supply. The monomer source is externally driven by the progressive addition into the system of one of the precursors. Monodisperse spherical particles are produced up to a mesoscopic size. We analyze their growth versus the monomer addition rate at different temperatures. Our results show that in the presence of a continuous monomer addition, growth is limited by diffusion over the investigated temporal window. Using the temperature variation of the growth rate, we prove that rescaling leads to a data reduction onto a single master curve. Contrary to the growth process, the final particle’s size reached after the end of the reagent supply strongly depends on the addition rate. The variation of the final particle size versus addition rate can be deduced from an analogy with crystal formation in jet precipitation. Within this framework, and using the temperature dependences of both the particle growth law and the final size, we determine the value of the molecular heat of dissolution associated to the silica solubility. These observations support the fact that classical theories of phase-ordering dynamics can be extended to the synthesis of inorganic particles. The emergence of a master behavior in the presence of continuous monomer addition also suggests the extension of these theories to open systems.

Dielectric properties of polymer-particle nanocomposites influenced by electronic nature of filler surfaces.

Science.gov (United States)

Siddabattuni, Sasidhar; Schuman, Thomas P; Dogan, Fatih

2013-03-01

The interface between the polymer and the particle has a critical role in altering the properties of a composite dielectric. Polymer-ceramic nanocomposites are promising dielectric materials for many electronic and power devices, combining the high dielectric constant of ceramic particles with the high dielectric breakdown strength of a polymer. Self-assembled monolayers of electron rich or electron poor organophosphate coupling groups were applied to affect the filler-polymer interface and investigate the role of this interface on composite behavior. The interface has potential to influence dielectric properties, in particular the leakage and breakdown resistance. The composite films synthesized from the modified filler particles dispersed into an epoxy polymer matrix were analyzed by dielectric spectroscopy, breakdown strength, and leakage current measurements. The data indicate that significant reduction in leakage currents and dielectric losses and improvement in dielectric breakdown strengths resulted when electropositive phenyl, electron-withdrawing functional groups were located at the polymer-particle interface. At a 30 vol % particle concentration, dielectric composite films yielded a maximum energy density of ~8 J·cm(-3) for TiO2-epoxy nanocomposites and ~9.5 J·cm(-3) for BaTiO3-epoxy nanocomposites.

Fabrication of monodisperse magnetic nanoparticles released in solution using a block copolymer template

Science.gov (United States)

Morcrette, Mélissa; Ortiz, Guillermo; Tallegas, Salomé; Joisten, Hélène; Tiron, Raluca; Baron, Thierry; Hou, Yanxia; Lequien, Stéphane; Bsiesy, Ahmad; Dieny, Bernard

2017-07-01

This paper describes a fabrication process of monodisperse magnetic nanoparticles released in solution, based on combined ‘top-down’ and ‘bottom-up’ approaches. The process involves the use of a self-assembled PS-PMMA block copolymer formed on a sacrificial layer. Such an approach was so far mostly explored for the preparation of patterned magnetic media for ultrahigh density magnetic storage. It is here extended to the preparation of released monodisperse nanoparticles for biomedical applications. A special sacrificial layer had to be developed compatible with the copolymer self-organization. The resulting nanoparticles exhibit very narrow size dispersion (≈7%) and can be good candidates as contrast agents for medical imaging i.e. magnetic resonance imaging or magnetic particle imaging. The approach provides a great freedom in the choice of the particles shapes and compositions. In particular, they can be made of biocompatible magnetic material.

Fabrication of monodisperse magnetic nanoparticles released in solution using a block copolymer template

International Nuclear Information System (INIS)

Morcrette, Mélissa; Ortiz, Guillermo; Joisten, Hélène; Dieny, Bernard; Tallegas, Salomé; Baron, Thierry; Bsiesy, Ahmad; Tiron, Raluca; Hou, Yanxia; Lequien, Stéphane

2017-01-01

This paper describes a fabrication process of monodisperse magnetic nanoparticles released in solution, based on combined ‘top-down’ and ‘bottom-up’ approaches. The process involves the use of a self-assembled PS-PMMA block copolymer formed on a sacrificial layer. Such an approach was so far mostly explored for the preparation of patterned magnetic media for ultrahigh density magnetic storage. It is here extended to the preparation of released monodisperse nanoparticles for biomedical applications. A special sacrificial layer had to be developed compatible with the copolymer self-organization. The resulting nanoparticles exhibit very narrow size dispersion (≈7%) and can be good candidates as contrast agents for medical imaging i.e. magnetic resonance imaging or magnetic particle imaging. The approach provides a great freedom in the choice of the particles shapes and compositions. In particular, they can be made of biocompatible magnetic material. (paper)

Crystallisation and structural studies of monodisperse nylon oligomers and related polymers

International Nuclear Information System (INIS)

Sikorski, P.T.

2001-11-01

Using electron and X-ray diffraction data, together with computerised molecular modeling, the structures of monodisperse nylon oligomers and related polymers have been investigated. Structural changes on heating were also studied. The molecules were crystallised from solution and their morphologies examined using optical and transmission electron microscopy. Lath-like lamellar crystals of the polyester poly-β-propiolactone were crystallised isothermally. The interpretation of the diffraction data with the use of molecular modeling led to the discovery of the new crystalline structure, the γ-structure. In the γ-structure, the polyester chain is in an all-trans conformation and the structure consists of a two-chain, basal-faced, orthorhombic unit cell. The setting angles, with respect to the a axis, are ± 51.5 deg for the corner and centre chains, respectively. The lamellae are 5 nm in thickness and the chains run orthogonal to the lamellar surface. The general fold direction is along the a-axis (long axis of the crystal) and the chain folds successively in the [110] and [11-bar0] directions. Three different nylon 4 6 oligomers were crystallised from solution using a range of crystallisation methods. The 4- and 8-amide molecules were found to form three-dimensional crystals, in which the crystal thickness was much greater than the molecular length. The structure was found to be different from the nylon 4 6 polymer reported previously. It was found that the type of hydrogen-bonded sheet formed by these molecules can influence the way in which these sheets stack to form crystals. In addition, a study of the 9-amide molecule showed that a particular type of hydrogen-bonded sheet, a-sheet, is preferred for nylon 4 6. This discovery suggests that an amide unit is found in the fold in the chain-folded nylon 4 6 polymer crystals, to allow the a-sheets to be formed. It is not a consequence of a need to form a stress-free fold. In the regular adjacent re-entry chain

Mass production of polymer nano-wires filled with metal nano-particles.

Science.gov (United States)

Lomadze, Nino; Kopyshev, Alexey; Bargheer, Matias; Wollgarten, Markus; Santer, Svetlana

2017-08-17

Despite the ongoing progress in nanotechnology and its applications, the development of strategies for connecting nano-scale systems to micro- or macroscale elements is hampered by the lack of structural components that have both, nano- and macroscale dimensions. The production of nano-scale wires with macroscale length is one of the most interesting challenges here. There are a lot of strategies to fabricate long nanoscopic stripes made of metals, polymers or ceramics but none is suitable for mass production of ordered and dense arrangements of wires at large numbers. In this paper, we report on a technique for producing arrays of ordered, flexible and free-standing polymer nano-wires filled with different types of nano-particles. The process utilizes the strong response of photosensitive polymer brushes to irradiation with UV-interference patterns, resulting in a substantial mass redistribution of the polymer material along with local rupturing of polymer chains. The chains can wind up in wires of nano-scale thickness and a length of up to several centimeters. When dispersing nano-particles within the film, the final arrangement is similar to a core-shell geometry with mainly nano-particles found in the core region and the polymer forming a dielectric jacket.

Preparation of submicrometer monodispersed magnetic silica particles using a novel water in oil microemulsion: properties and application for enzyme immobilization.

Science.gov (United States)

Tuttolomondo, Maria Victoria; Villanueva, Maria Emilia; Alvarez, Gisela Solange; Desimone, Martín Federico; Díaz, Luis Eduardo

2013-10-01

The synthesis of monodispersed magnetic silica nanoparticles (MSN) is described using a water-in-oil reverse microemulsion system that does not require the use of co-surfactants. Sodium silicate, Tween 20 as a neutral surfactant and 1-butanol as the organic phase were used. There are several advantages of the proposed method including a saturation magnetization value of 10 emu/g for the particles obtained, uniformity of size and that they are easily functionalized to bind urease covalently. Moreover, the intra-day, inter-day and long-term stability results confirm that the procedure was successful and the enzyme-linked MSNs were stable over repeated uses and storage retaining more than 75% activity after 4 months.

Impact of in situ polymer coating on particle dispersion into solid laser-generated nanocomposites.

Science.gov (United States)

Wagener, Philipp; Brandes, Gudrun; Schwenke, Andreas; Barcikowski, Stephan

2011-03-21

The crucial step in the production of solid nanocomposites is the uniform embedding of nanoparticles into the polymer matrix, since the colloidal properties or specific physical properties are very sensitive to particle dispersion within the nanocomposite. Therefore, we studied a laser-based generation method of a nanocomposite which enables us to control the agglomeration of nanoparticles and to increase the single particle dispersion within polyurethane. For this purpose, we ablated targets of silver and copper inside a polymer-doped solution of tetrahydrofuran by a picosecond laser (using a pulse energy of 125 μJ at 33.3 kHz repetition rate) and hardened the resulting colloids into solid polymers. Electron microscopy of these nanocomposites revealed that primary particle size, agglomerate size and particle dispersion strongly depend on concentration of the polyurethane added before laser ablation. 0.3 wt% polyurethane is the optimal polymer concentration to produce nanocomposites with improved particle dispersion and adequate productivity. Lower polyurethane concentration results in agglomeration whereas higher concentration reduces the production rate significantly. The following evaporation step did not change the distribution of the nanocomposite inside the polyurethane matrix. Hence, the in situ coating of nanoparticles with polyurethane during laser ablation enables simple integration into the structural analogue polymer matrix without additives. Furthermore, it was possible to injection mold these in situ-stabilized nanocomposites without affecting particle dispersion. This clarifies that sufficient in situ stabilization during laser ablation in polymer solution is able to prevent agglomeration even in a hot polymer melt.

TiO2 thin-films on polymer substrates and their photocatalytic activity

International Nuclear Information System (INIS)

Yang, Jae-Hun; Han, Yang-Su; Choy, Jin-Ho

2006-01-01

We have developed dip-coating process for TiO 2 -thin film on polymer substrates (acrylonitrile-butadiene-styrene polymer: ABS, polystyrene: PS). At first, a monodispersed and transparent TiO 2 nano-sol solution was prepared by the controlled hydrolysis of titanium iso-propoxide in the presence of acetylacetone and nitric acid catalyst at 80 deg. C. Powder X-ray diffraction patterns of the dried particles are indicative of crystalline TiO 2 with anatase-type structure. According to the XRD and transmission electron microscopy (TEM) studies, the mean particle size was estimated to be ca. 5 nm. The transparent thin films on ABS and PS substrates were fabricated by dip-coating process by changing the processing variables, such as the number of dip-coating and TiO 2 concentration in nano-sol solution. Scanning electron microscopic (SEM) analysis for the thin film samples reveals that the acetylacetone-modified TiO 2 nano-sol particles are effective for enhancing the interfacial adherence between films and polymeric substrates compared to the unmodified one. Photocatalytic degradation of methylene blue (MB) on the TiO 2 thin-films has also been systematically investigated

25th Anniversary Article: Polymer-Particle Composites: Phase Stability and Applications in Electrochemical Energy Storage

KAUST Repository

Srivastava, Samanvaya

2013-12-09

Polymer-particle composites are used in virtually every field of technology. When the particles approach nanometer dimensions, large interfacial regions are created. In favorable situations, the spatial distribution of these interfaces can be controlled to create new hybrid materials with physical and transport properties inaccessible in their constituents or poorly prepared mixtures. This review surveys progress in the last decade in understanding phase behavior, structure, and properties of nanoparticle-polymer composites. The review takes a decidedly polymers perspective and explores how physical and chemical approaches may be employed to create hybrids with controlled distribution of particles. Applications are studied in two contexts of contemporary interest: battery electrolytes and electrodes. In the former, the role of dispersed and aggregated particles on ion-transport is considered. In the latter, the polymer is employed in such small quantities that it has been historically given titles such as binder and carbon precursor that underscore its perceived secondary role. Considering the myriad functions the binder plays in an electrode, it is surprising that highly filled composites have not received more attention. Opportunities in this and related areas are highlighted where recent advances in synthesis and polymer science are inspiring new approaches, and where newcomers to the field could make important contributions. Polymer-particle composites are used in virtually every field of technology. When the particles approach nanometer dimensions, large interfacial regions are created that can be exploited for applications. The fundamental approaches and bottom-up synthesis strategies for understanding and controlling nanoparticle dispersion in polymers are reviewed. Applications of these approaches for creating polymer-particle composite electrolytes and electrodes for energy storage are also considered. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Toxicity of inhaled 238PuO2 in Beagle dogs: A. Monodisperse 1.5 μm AMAD particles. B. Monodisperse 3.0 μm particles. XV

International Nuclear Information System (INIS)

Mewhinney, J.A.; Gillett, N.A.; Muggenburg, B.A.; Hahn, F.F.; Diel, J.H.; Mauderly, J.L.; Boecker, B.B.; McClellan, R.O.

1988-01-01

Beagle dogs inhaled one of two sizes of monodisperse aerosols of 238 PuO 2 that resulted in graded levels of 238 Pu in the lung. All dogs are being studied for their life span. One hundred and thirty-seven dogs that had initial lung burdens ranging from 0.01 to 1.5 μCi 238 Pu/kg body weight (0.37 to 56 kBq/kg) have died, 8 with radiation pneumonitis and pulmonary fibrosis, 8 with lung tumors, 88 with bone tumors, 10 with liver tumors, and 25 of miscellaneous causes. Eighteen control dogs have died. Observations are being continued on 8 exposed and 6 control dogs alive at 4577-5274 days after exposure. (author)

Photoelectrochemical performance of DSSC with monodisperse and polydisperse ZnO SPs

Energy Technology Data Exchange (ETDEWEB)

Wahyuono, Ruri Agung, E-mail: r-agung-w@ep.its.ac.id; Risanti, Doty D., E-mail: r-agung-w@ep.its.ac.id [Department of Engineering Physics, Institut Teknologi Sepuluh Nopember (Indonesia); Shirosaki, Tomohiro; Nagaoka, Shoji [Kumamoto Industrial Research Institute (Japan); Takafuji, Makoto; Ihara, Hirotaka [Department of Applied Chemistry and Biochemistry, Kumamoto University (Japan)

2014-02-24

Zinc oxide, ZnO, is one of oxide semiconductors being used in DSSC. ZnO is promising material for having fairly higher energy band gap and much higher bulk electron mobility than that of anatase TiO{sub 2}, the most widely used semiconductor for DSSC photoelectrode. This study introduces the synthesis of ZnO by precipitation method. The synthesis involves ZnAc dihydrate and diethylene glycol (DEG) for the chemicals. Various size of ZnO spherical particles (SPs) are obtained in polydisperse and monodisperse particles. Monolayer and bilayer DSSCs are fabricated in sandwich structure and sensitized with N719 dye for 3 and 5 hours. Monolayer DSSC using monodisperse particles (422 nm) is able to generate highest conversion efficiency of 0.569% (V{sub oc} = 541.3 mV, J{sub sc} = 1.92 mA/cm{sup 2}, and fill factor of 54.78%). Bilayer DSSC, i.e. combined 422 - 185 nm ZnO layer, can optimize the photocurrent action spectra in UV regime leading to high conversion efficiency of 0.568 (V{sub oc} = 568.2 mV, J{sub sc} = 2.22 mA/cm{sup 2}, and fill factor of 47.25%). The longer sensitizing time does not always produce better conversion efficiency since it can induce the dissolution of Zn atoms and formation of Zn{sup 2+} - dye resisting the electron transport from dye to ZnO photoelectrode.

Characterization of Monodispersed Iron Oxide Nanocrystals by XAS and MCD measurement

International Nuclear Information System (INIS)

Kim, J.-Y.; Noh, H.-J.; Park, B.-G.; Kim, T.-Y.; Park, J.-H.; Hyeon, T.; Park, J.; Kang, E.

2004-01-01

Full text: Nanoparticles have attracted so much attention because of their potential technological applications and abundance of scientifically interesting issues. In particular, magnetic nanoparticles are considered to be applicable to various magnetic devices such as terabit memory, ferrofluids, magnetocaloric refrigeration systems, blood cells, etc. With the development of nano-technology, variation of physical properties as a function of particle size is one of the most important issues, but has been rarely explored because of difficulty of the size control in synthesizing nanoparticles. Recently, some of us successfully synthesized high crystalline and monodisperse maghemite nanoparticles without a size selection process and research in this field seems to be promoted by one step. In this report, we present a systematic characterization of the monodispersed nanocrystalline γ - Fe 2 O 3 with the diameter of 13, 8 and 4 nm by measuring the x-ray absorption spectroscopy (XAS) and the x-ray magnetic circular dichroism(XMCD) spectra on Fe L edge. The spectra of the 4 nm nanoparticles are very similar to those of maghemite (γ - Fe 2 O 3 ). However, the spectra become close to those of magnetite (Fe 3 O 4 ) as the particle size becomes 8 and 13 nm. Considering that the maghemite and magnetite have the same spinel structure with different Fe vacancies, these results can be explained that the surface of nanoparticles has more vacancies than the core part, indicating that surface disorder increases as the particle size decreases

Quantitative structure-activity relationships for green algae growth inhibition by polymer particles.

Science.gov (United States)

Nolte, Tom M; Peijnenburg, Willie J G M; Hendriks, A Jan; van de Meent, Dik

2017-07-01

After use and disposal of chemical products, many types of polymer particles end up in the aquatic environment with potential toxic effects to primary producers like green algae. In this study, we have developed Quantitative Structure-Activity Relationships (QSARs) for a set of highly structural diverse polymers which are capable to estimate green algae growth inhibition (EC50). The model (N = 43, R 2  = 0.73, RMSE = 0.28) is a regression-based decision tree using one structural descriptor for each of three polymer classes separated based on charge. The QSAR is applicable to linear homo polymers as well as copolymers and does not require information on the size of the polymer particle or underlying core material. Highly branched polymers, non-nitrogen cationic polymers and polymeric surfactants are not included in the model and thus cannot be evaluated. The model works best for cationic and non-ionic polymers for which cellular adsorption, disruption of the cell wall and photosynthesis inhibition were the mechanisms of action. For anionic polymers, specific properties of the polymer and test characteristics need to be known for detailed assessment. The data and QSAR results for anionic polymers, when combined with molecular dynamics simulations indicated that nutrient depletion is likely the dominant mode of toxicity. Nutrient depletion in turn, is determined by the non-linear interplay between polymer charge density and backbone flexibility. Copyright © 2017 Elsevier Ltd. All rights reserved.

Preparation and unique electrical behaviors of monodispersed hybrid nanorattles of metal nanocores with hairy electroactive polymer shells.

Science.gov (United States)

Cai, Tao; Zhang, Bin; Chen, Yu; Wang, Cheng; Zhu, Chun Xiang; Neoh, Koon-Gee; Kang, En-Tang

2014-03-03

A versatile template-assisted strategy for the preparation of monodispersed rattle-type hybrid nanospheres, encapsulating a movable Au nanocore in the hollow cavity of a hairy electroactive polymer shell (Au@air@PTEMA-g-P3HT hybrid nanorattles; PTEMA: poly(2-(thiophen-3-yl)ethyl methacrylate; P3HT: poly(3-hexylthiophene), was reported. The Au@silica core-shell nanoparticles, prepared by the modified Stöber sol-gel process on Au nanoparticle seeds, were used as templates for the synthesis of Au@silica@PTEMA core-double shell nanospheres. Subsequent oxidative graft polymerization of 3-hexylthiophene from the exterior surface of the Au@silica@PTEMA core-double shell nanospheres allowed the tailoring of surface functionality with electroactive P3HT brushes (Au@silica@PTEMA-g-P3HT nanospheres). The Au@air@ PTEMA-g-P3HT hybrid nanorattles were obtained after etching of the silica interlayer by HF. The as-prepared nanorattles were dispersed into an electrically insulating polystyrene matrix and for the first time used to fabricate nonvolatile memory devices. As a result, unique electrical behaviors, including insulator behavior, write-once-read-many-times and rewritable memory effects, and conductor behavior as well, were observed in the Al/Au@air@PTEMA-g-P3HT+PS/ITO (ITO: indium-tin oxide) sandwich thin-film devices. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Molecular dynamics simulations of the embedding of a nano-particle into a polymer film

International Nuclear Information System (INIS)

Ochoa, J G Diaz; Binder, K; Paul, W

2006-01-01

In this work we report on molecular dynamics simulations of the embedding process of a nano-particle into a polymeric film as a function of temperature. This process has been employed experimentally in recent years to test for a shift of the glass transition of a material due to the confined film geometry and to test for the existence of a liquid-like layer on top of a glassy polymer film. The embedding process is governed thermodynamically by the prewetting properties of the polymer on the nano-particle. We show that the dynamics of the process depends on the Brownian motion characteristics of the nano-particle in and on the polymer film. It displays large sample to sample variations, suggesting that it is an activated process. On the timescales of the simulation an embedding of the nano-particle is only observed for temperatures above the bulk glass transition temperature of the polymer, agreeing with experimental observations on noble metal clusters of comparable size

Superconducting lead particles produced by chemical techniques

Science.gov (United States)

Fariss, T. L.; Nixon, W. E.; Bucelot, T. J.; Deaver, B. S., Jr.; Mitchell, J. W.

1982-09-01

The superconductivity of extremely small lead particles has been studied as a function of size, surface condition, and connectivity using chemical techniques to produce particles of well-controlled size and shape suspended in insulating media. Approximately monodisperse suspensions of equiaxed, rod, and lath-shaped particles of lead halides and other lead compounds suspended in gelatin, polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, methyl cellulose, and hydroxyethyl cellulose have been produced. These particles have been reduced to pseudomorphs of lead in the liquid phase or the suspensions have been coated on substrates and dried before reduction. Reducing solutions containing aminoiminomethanesulfinic acid are effective with particles of lead halides, lead phosphate, lead sulfate, and lead tartrate. Suspensions of smaller discrete lead particles have also been produced by direct reduction of solutions of soluble lead salts containing suitable polymers, chelating, and stabilizing agents. Dispersions with mean particle dimensions between 3 nm and 5 μm, and a narrow size-frequency distribution, have been produced. The superconductivity of the particles has been characterized by measurements of the magnetization as a function of temperature and magnetic field. The larger particles have a transition temperature of 7.2 K, the same as bulk lead; however, for particles of characteristic dimensions less than 20 nm, the transition temperature is lower by ˜0.1 K.

Superconducting lead particles produced by chemical techniques

International Nuclear Information System (INIS)

Fariss, T.L.; Nixon, W.E.; Bucelot, T.J.; Deaver, B.S. Jr.; Mitchell, J.W.

1982-01-01

The superconductivity of extremely small lead particles has been studied as a function of size, surface condition, and connectivity using chemical techniques to produce particles of well-controlled size and shape suspended in insulating media. Approximately monodisperse suspensions of equiaxed, rod, and lath-shaped particles of lead halides and other lead compounds suspended in gelatin, polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, methyl cellulose, and hydroxyethyl cellulose have been produced. These particles have been reduced to pseudomorphs of lead in the liquid phase or the suspensions have been coated on substrates and dried before reduction. Reducing solutions containing aminoiminomethanesulfinic acid are effective with particles of lead halides, lead phosphate, lead sulfate, and lead tartrate. Suspensions of smaller discrete lead particles have also been produced by direct reduction of solutions of soluble lead salts containing suitable polymers, chelating, and stabilizing agents. Dispersions with mean particle dimensions between 3 nm and 5 μm, and a narrow size-frequency distribution, have been produced. The superconductivity of the particles has been characterized by measurements of the magnetization as a function of temperature and magnetic field. The larger particles have a transition temperature of 7.2 K, the same as bulk lead; however, for particles of characteristic dimensions less than 20 nm, the transition temperature is lower by approx.0.1 K

Dynamic dilution exponent in monodisperse entangled polymer solutions

DEFF Research Database (Denmark)

Shahid, T.; Huang, Qian; Oosterlinck, F.

2017-01-01

of concentration but also depends on the molar mass of the chains. While the proposed approach successfully explains the viscoelastic properties of a large number of semi-dilute solutions of polymers in their own oligomers, important discrepancies are found for semi-dilute entangled polymers in small-molecule......We study and model the linear viscoelastic properties of several entangled semi-dilute and concentrated solutions of linear chains of different molar masses and at different concentrations dissolved in their oligomers. We discuss the dilution effect of the oligomers on the entangled long chains....... In particular, we investigate the influence of both concentration and molar mass on the value of the effective dynamic dilution exponent determined from the level of the storage plateau at low and intermediate frequencies. We show that the experimental results can be quantitatively explained by considering...

Surface-selective laser sintering of thermolabile polymer particles using water as heating sensitizer

Energy Technology Data Exchange (ETDEWEB)

Antonov, E N; Krotova, L I; Minaev, N V; Minaeva, S A; Mironov, A V; Popov, V K [Institute on Laser and Information Technologies of the Russian Academy of Sciencies, Troitsk, Moscow (Russian Federation); Bagratashvili, V N [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

2015-11-30

We report the implementation of a novel scheme for surface-selective laser sintering (SSLS) of polymer particles, based on using water as a sensitizer of laser heating and sintering of particles as well as laser radiation at a wavelength of 1.94 μm, corresponding to the strong absorption band of water. A method of sintering powders of poly(lactide-co-glycolide), a hydrophobic bioresorbable polymer, after modifying its surface with an aqueous solution of hyaluronic acid is developed. The sintering thresholds for wetted polymer are by 3 – 4 times lower than those for sintering in air. The presence of water restricts the temperature of the heated polymer, preventing its thermal destruction. Polymer matrices with a developed porous structure are obtained. The proposed SSLS method can be applied to produce bioresorbable polymer matrices for tissue engineering. (interaction of laser radiation with matter. laser plasma)

Multiscale structure, interfacial cohesion, adsorbed layers, miscibility and properties in dense polymer-particle mixtures

Science.gov (United States)

Schweizer, Ken

2012-02-01

A major goal in polymer nanocomposite research is to understand and predict how the chemical and physical nature of individual polymers and nanoparticles, and thermodynamic state (temperature, composition, solvent dilution, filler loading), determine bulk assembly, miscibility and properties. Microscopic PRISM theory provides a route to this goal for equilibrium disordered mixtures. A major prediction is that by manipulating the net polymer-particle interfacial attraction, miscibility is realizable via the formation of thin thermodynamically stable adsorbed layers, which, however, are destroyed by entropic depletion and bridging attraction effects if interface cohesion is too weak or strong, respectively. This and related issues are quantitatively explored for miscible mixtures of hydrocarbon polymers, silica nanospheres, and solvent using x-ray scattering, neutron scattering and rheology. Under melt conditions, quantitative agreement between theory and silica scattering experiments is achieved under both steric stabilization and weak depletion conditions. Using contrast matching neutron scattering to characterize the collective structure factors of polymers, particles and their interface, the existence and size of adsorbed polymer layers, and their consequences on microstructure, is determined. Failure of the incompressible RPA, accuracy of PRISM theory, the nm thickness of adsorbed layers, and qualitative sensitivity of the bulk modulus to interfacial cohesion and particle size are demonstrated for concentrated PEO-silica-ethanol nanocomposites. Temperature-dependent complexity is discovered when water is the solvent, and nonequilibrium effects emerge for adsorbing entangled polymers that strongly impact structure. By varying polymer chemistry, the effect of polymer-particle attraction on the intrinsic viscosity is explored with striking non-classical effects observed. This work was performed in collaboration with S.Y.Kim, L.M.Hall, C.Zukoski and B.Anderson.

Preparation and drug-loading properties of Fe3O4/Poly(styrene-co-acrylic acid) magnetic polymer nanocomposites

International Nuclear Information System (INIS)

Lu, Wensheng; Shen, Yuhua; Xie, Anjian; Zhang, Weiqiang

2013-01-01

Fe 3 O 4 /poly(styrene-co-acrylic acid) magnetic polymer nanocomposites were synthesized by the dispersion polymerization method using styrene as hard monomer, acrylic acid as functional monomer, Fe 3 O 4 nanoparticles modified with oleic acid as core, and poly(styrene-co-acrylic acid) as shell. Drug-loading properties of magnetic polymer nanocomposites with curcumin as a model drug were also studied. The results indicated that magnetic polymer nanocomposites with monodisperse were obtained, the particle size distribution was 50–120 nm, and the average size was about 100 nm. The contents of poly(styrene-co-acrylic acid) and Fe 3 O 4 nanoparticles in magnetic polymer nanocomposites were 74% and 24.7%, respectively. The drug-loading capacity and entrapment efficiency were 2.5% and 44.4%, respectively. The saturation magnetization of magnetic polymer nanocomposites at 300 K was 20.2 emu/g without coercivity and remanence. The as-prepared magnetic polymer nanocomposites have not only lots of functional carboxyl groups but also stronger magnetic response, which might have potential applications in drug carrier and targeted drug release

Optimization of mechanical performance of oxidative nano-particle electrode nitrile butadiene rubber conducting polymer actuator.

Science.gov (United States)

Kim, Baek-Chul; Park, S J; Cho, M S; Lee, Y; Nam, J D; Choi, H R; Koo, J C

2009-12-01

Present work delivers a systematical evaluation of actuation efficiency of a nano-particle electrode conducting polymer actuator fabricated based on Nitrile Butadiene Rubber (NBR). Attempts are made for maximizing mechanical functionality of the nano-particle electrode conducting polymer actuator that can be driven in the air. As the conducting polymer polypyrrole of the actuator is to be fabricated through a chemical oxidation polymerization process that may impose certain limitations on both electrical and mechanical functionality of the actuator, a coordinated study for optimization process of the actuator is necessary for maximizing its performance. In this article actuation behaviors of the nano-particle electrode polypyrrole conducting polymer is studied and an optimization process for the mechanical performance maximization is performed.

Inhibition of surface crystallisation of amorphous indomethacin particles in physical drug-polymer mixtures

DEFF Research Database (Denmark)

Priemel, Petra A; Laitinen, Riikka; Barthold, Sarah

2013-01-01

stability than pure IMC whereas IMC Soluplus(®) mixtures did not. Water uptake was higher for mixtures containing Soluplus(®) than for amorphous IMC or IMC Eudragit(®) mixtures. However, the Tg of amorphous IMC was unaffected by the presence (and nature) of polymer. SEM revealed that Eudragit(®) particles...... through reduced IMC surface molecular mobility. Polymer particles may also mechanically hinder crystal growth outwards from the surface. This work highlights the importance of microparticulate surface coverage of amorphous drug particles on their stability....

Submicron polymer particles containing fluorescent semiconductor nanocrystals CdSe/ZnS for bioassays.

Science.gov (United States)

Generalova, Alla N; Sizova, Svetlana V; Zdobnova, Tatiana A; Zarifullina, Margarita M; Artemyev, Michail V; Baranov, Alexander V; Oleinikov, Vladimir A; Zubov, Vitaly P; Deyev, Sergey M

2011-02-01

This study aimed to design a panel of uniform particulate biochemical reagents and to test them in specific bioassays. These reagents are polymer particles of different sizes doped with semiconductor nanocrystals and conjugated with either full-size antibodies or recombinant mini-antibodies (4D5 scFv fragment) designed by genetic engineering approaches. A panel of highly fluorescent polymer particles (150-800 nm) were formed by embedding CdSe/ZnS nanocrystals (quantum dots) into preformed polyacrolein and poly(acrolein-co-styrene) particles. Morphology, content and fluorescence characteristics of the prepared materials were studied by laser correlation spectroscopy, spectrophotometry, optical and fluorescent microscopy and fluorimetry. The obtained fluorescent particles sensitized by anti-Yersinia pestis antibodies were used for rapid agglutination glass test suitable for screening analysis of Y. pestis antigen and for microtiter particle agglutination, which, owing to its speed and simplicity, is very beneficial for diagnostic detection of Y. pestis antigen. Recombinant 4D5 scFv antibodies designed and conjugated with polymer particles containing quantum dots provide multipoint highly specific binding with cancer marker HER2/neu on the surface of SKOV-3 cell.

Catastrophic failure of polymer melts during extension

DEFF Research Database (Denmark)

Rasmussen, Henrik K.

2013-01-01

Numerical flow modeling has been applied to study the break of monodisperse polymer melts during extension. These continuum mechanical based computations are within the ideas of the microstructural ’interchain pressure’ theory. Calculated breaks, a result of small initial sample imperfections, ag...

Fabrication of Phase-Change Polymer Colloidal Photonic Crystals

Directory of Open Access Journals (Sweden)

Tianyi Zhao

2014-01-01

Full Text Available This paper presents the preparation of phase-change polymer colloidal photonic crystals (PCs by assembling hollow latex spheres encapsulated with dodecanol for the first time. The monodispersed hollow latex spheres were obtained by phase reversion of monodispersed core-shell latex spheres in the n-hexane, which dissolves the PS core and retains the PMMA/PAA shell. The as-prepared phase-change colloidal PCs show stable phase-change behavior. This fabrication of phase-change colloidal PCs would be significant for PC’s applications in functional coatings and various optic devices.

Polymer nanocomposites: polymer and particle dynamics

KAUST Repository

Kim, Daniel; Srivastava, Samanvaya; Narayanan, Suresh; Archer, Lynden A.

2012-01-01

Polymer nanocomposites containing nanoparticles smaller than the random coil size of their host polymer chains are known to exhibit unique properties, such as lower viscosity and glass transition temperature relative to the neat polymer melt. It has

Preparation of monodisperse porous silica particles using poly(glycidyl methacrylate) microspheres as a template

Czech Academy of Sciences Publication Activity Database

Grama, Silvia; Horák, Daniel

2015-01-01

Roč. 64, Suppl. 1 (2015), S11-S17 ISSN 0862-8408 R&D Projects: GA MŠk(CZ) EE2.3.30.0029; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61389013 Keywords : microspheres * monodisperse * silica Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.643, year: 2015 http://www.biomed.cas.cz/physiolres/pdf/64%20Suppl%201/64_S11.pdf

The synthesis and characterization of water-reducible nanoscale Colloidal Unimolecular Polymer (CUP) particles

Science.gov (United States)

Riddles, Cynthia Jeannette

The coatings industry has adapted to more stringent guidelines in paint formulations. Current VOC (volatile organic compound) limits placed by the federal government have pushed the industry toward the development of paint formulations which have very little to no VOC's. The development of Colloidal Unimolecular Polymer (CUP) particles is a step in the direction of providing a resin system which exists in zero VOC aqueous dispersion. The CUP particles are a part of the polymer field of Single Chain Nano Particles (SCNP) and ranged in diameters of 3-9 nm. The research presented in this dissertation describes the synthesis and design of these particles along with the various means of instrumentation used to gain insight into the structure and nature of these particles when suspended in aqueous medium.

Synthesis of raspberry-like monodisperse magnetic hollow hybrid nanospheres by coating polystyrene template with Fe(3)O(4)@SiO(2) particles.

Science.gov (United States)

Wang, Chunlei; Yan, Juntao; Cui, Xuejun; Wang, Hongyan

2011-02-01

In this paper, we present a novel method for the preparation of raspberry-like monodisperse magnetic hollow hybrid nanospheres with γ-Fe(2)O(3)@SiO(2) particles as the outer shell. PS@Fe(3)O(4)@SiO(2) composite nanoparticles were successfully prepared on the principle of the electrostatic interaction between negatively charged silica and positively charged polystyrene, and then raspberry-like magnetic hollow hybrid nanospheres with large cavities were achieved by means of calcinations, simultaneously, the magnetite (Fe(3)O(4)) was transformed into maghemite (γ-Fe(2)O(3)). Transmission electron microscopy (TEM) demonstrated that the obtained magnetic hollow silica nanospheres with the perfect spherical profile were well monodisperse and uniform with the mean size of 253nm. The Fourier transform infrared (FTIR) spectrometry, energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) provided the sufficient evidences for the presence of Fe(3)O(4) in the silica shell. Moreover, the magnetic hollow silica nanospheres possessed a characteristic of superparamagnetic with saturation magnetization value of about 7.84emu/g by the magnetization curve measurement. In addition, the nitrogen adsorption-desorption measurement exhibited that the pore size, BET surface area, pore volume of magnetic hollow silica nanospheres were 3.5-5.5nm, 307m(2)g(-1) and 1.33cm(3)g(-1), respectively. Therefore, the magnetic hollow nanospheres possess a promising future in controlled drug delivery and targeted drug applications. Copyright © 2010 Elsevier Inc. All rights reserved.

Preparation and characterization of monodisperse large-porous silica microspheres as the matrix for protein separation.

Science.gov (United States)

Xia, Hongjun; Wan, Guangping; Zhao, Junlong; Liu, Jiawei; Bai, Quan

2016-11-04

High performance liquid chromatography (HPLC) is a kind of efficient separation technology and has been used widely in many fields. Micro-sized porous silica microspheres as the most popular matrix have been used for fast separation and analysis in HPLC. In this paper, the monodisperse large-porous silica microspheres with controllable size and structure were successfully synthesized with polymer microspheres as the templates and characterized. First, the poly(glycidyl methacrylate-co-ethyleneglycol dimethacrylate) microspheres (P GMA-EDMA ) were functionalized with tetraethylenepentamine (TEPA) to generate amino groups which act as a catalyst in hydrolysis of tetraethyl orthosilicate (TEOS) to form Si-containing low molecular weight species. Then the low molecular weight species diffused into the functionalized P GMA-EDMA microspheres by induction force of the amino groups to form polymer/silica hybrid microspheres. Finally, the organic polymer templates were removed by calcination, and the large-porous silica microspheres were obtained. The compositions, morphology, size distribution, specific surface area and pore size distribution of the porous silica microspheres were characterized by infrared analyzer, scanning-electron microscopy, dynamic laser scattering, the mercury intrusion method and thermal gravimetric analysis, respectively. The results show that the agglomeration of the hybrid microspheres can be overcome when the templates were functionalized with TEPA as amination reagent, and the yield of 95.7% of the monodisperse large-porous silica microspheres can be achieved with high concentration of polymer templates. The resulting large-porous silica microspheres were modified with octadecyltrichlorosilane (ODS) and the chromatographic evaluation was performed by separating the proteins and the digest of BSA. The baseline separation of seven kinds of protein standards was achieved, and the column delivered a better performance when separating BSA digests

Elongational viscosity of monodisperse and bidisperse polystyrene melts

DEFF Research Database (Denmark)

Nielsen, Jens Kromann; Rasmussen, Henrik K.; Hassager, Ole

2006-01-01

The start-up and steady uniaxial elongational viscosity have been measured for two monodisperse polystyrene melts with molecular weights of 52 and 103 kg/mole, and for three bidisperse polystyrene melts. The monodisperse melts show a maximum in the steady elongational viscosity vs. the elongational...

Self-diffusion in monodisperse three-dimensional magnetic fluids by molecular dynamics simulations

Energy Technology Data Exchange (ETDEWEB)

Dobroserdova, A.B. [Ural Federal University, Lenin Av. 51, Ekaterinburg (Russian Federation); Kantorovich, S.S., E-mail: alla.dobroserdova@urfu.ru [Ural Federal University, Lenin Av. 51, Ekaterinburg (Russian Federation); University of Vienna, Sensengasse 8, Vienna (Austria)

2017-06-01

In the present work we study the self-diffusion behaviour in the three-dimensional monodisperse magnetic fluids using the Molecular Dynamics Simulation and Density Functional Theory. The peculiarity of computer simulation is to study two different systems: dipolar and soft sphere ones. In the theoretical method, it is important to choose the approximation for the main structures, which are chains. We compare the theoretical results and the computer simulation data for the self-diffusion coefficient as a function of the particle volume fraction and magnetic dipole-dipole interaction parameter and find the qualitative and quantitative agreement to be good. - Highlights: • The paper deals with the study of the self-diffusion in monodisperse three-dimensional magnetic fluids. • The theoretical approach contains the free energy density functional minimization. • Computer simulations are performed by the molecular dynamics method. • We have a good qualitative and quantitative agreement between the theoretical results and computer simulation data.

Selective transport of Fe(III) using ionic imprinted polymer (IIP) membrane particle

Science.gov (United States)

Djunaidi, Muhammad Cholid; Jumina, Siswanta, Dwi; Ulbricht, Mathias

2015-12-01

The membrane particles was prepared from polyvinyl alcohol (PVA) and polymer IIP with weight ratios of 1: 2 and 1: 1 using different adsorbent templates and casting thickness. The permeability of membrane towards Fe(III) and also mecanism of transport were studied. The selectivity of the membrane for Fe(III) was studied by performing adsorption experiments also with Cr(III) separately. In this study, the preparation of Ionic Imprinted Polymer (IIP) membrane particles for selective transport of Fe (III) had been done using polyeugenol as functional polymer. Polyeugenol was then imprinted with Fe (III) and then crosslinked with PEGDE under alkaline condition to produce polyeugenol-Fe-PEGDE polymer aggregates. The agrregates was then crushed and sieved using mesh size of 80 and the powder was then used to prepare the membrane particles by mixing it with PVA (Mr 125,000) solution in 1-Methyl-2-pyrrolidone (NMP) solvent. The membrane was obtained after casting at a speed of 25 m/s and soaking in NaOH solution overnight. The membrane sheet was then cut and Fe(III) was removed by acid to produce IIP membrane particles. Analysis of the membrane and its constituent was done by XRD, SEM and size selectivity test. Experimental results showed the transport of Fe(III) was faster with the decrease of membrane thickness, while the higher concentration of template ion correlates with higher Fe(III) being transported. However, the transport of Fe(III) was slower for higher concentration of PVA in the membrane. IImparticles works through retarded permeation mechanism, where Fe(III) was bind to the active side of IIP. The active side of IIP membrane was dominated by the -OH groups. The selectivity of all IIP membranes was confirmed as they were all unable to transport Cr (III), while NIP (Non-imprinted Polymer) membrane was able transport Cr (III).

Controlled Release from Recombinant Polymers

Science.gov (United States)

Price, Robert; Poursaid, Azadeh; Ghandehari, Hamidreza

2014-01-01

Recombinant polymers provide a high degree of molecular definition for correlating structure with function in controlled release. The wide array of amino acids available as building blocks for these materials lend many advantages including biorecognition, biodegradability, potential biocompatibility, and control over mechanical properties among other attributes. Genetic engineering and DNA manipulation techniques enable the optimization of structure for precise control over spatial and temporal release. Unlike the majority of chemical synthetic strategies used, recombinant DNA technology has allowed for the production of monodisperse polymers with specifically defined sequences. Several classes of recombinant polymers have been used for controlled drug delivery. These include, but are not limited to, elastin-like, silk-like, and silk-elastinlike proteins, as well as emerging cationic polymers for gene delivery. In this article, progress and prospects of recombinant polymers used in controlled release will be reviewed. PMID:24956486

Shearing of particles during crack growth in polymer blends

NARCIS (Netherlands)

Pijnenburg, K.G.W.; Steenbrink, A.C.; Giessen, E.V.D.

1999-01-01

Microstructural investigations below the fracture surface have revealed that the rubber particles in a number of polymer-rubber blends were deformed into remarkable S-like shapes. These shapes seem to have been largely ignored in previous microstructural studies of blends, but in fact cannot be

Bio-Functional, Lanthanide-Labeled Polymer Particles by Seeded Emulsion Polymerization and their Characterization by Novel ICP-MS Detection.

Science.gov (United States)

Thickett, Stuart C; Abdelrahman, Ahmed I; Ornatsky, Olga; Bandura, Dmitry; Baranov, Vladimir; Winnik, Mitchell A

2010-01-01

We present the synthesis and characterization of monodisperse, sub-micron poly(styrene) (PS) particles loaded with up to and including 10(7) lanthanide (Ln) ions per particle. These particles have been synthesized by seeded emulsion polymerization with a mixture of monomer and a pre-formed Ln complex, and analyzed on a particle-by-particle basis by a unique inductively coupled plasma mass cytometer. Seed particles were prepared by surfactant-free emulsion polymerization (SFEP) to obtain large particle sizes in aqueous media. Extensive surface acid functionality was introduced using the acid-functional initiator ACVA, either during seed latex synthesis or in the second stage of polymerization. The loading of particles with three different Ln ions (Eu, Tb, and Ho) has proven to be close to 100 % efficient on an individual and combined basis. Covalent attachment of metal-tagged peptides and proteins such as Neutravidin to the particle surface was shown to be successful and the number of bound species can be readily determined. We believe these particles can serve as precursors for multiplexed, bead-based bio-assays utilizing mass cytometric detection.

Particle-in-a-box model of one-dimensional excitons in conjugated polymers

Science.gov (United States)

Pedersen, Thomas G.; Johansen, Per M.; Pedersen, Henrik C.

2000-04-01

A simple two-particle model of excitons in conjugated polymers is proposed as an alternative to usual highly computationally demanding quantum chemical methods. In the two-particle model, the exciton is described as an electron-hole pair interacting via Coulomb forces and confined to the polymer backbone by rigid walls. Furthermore, by integrating out the transverse part, the two-particle equation is reduced to one-dimensional form. It is demonstrated how essentially exact solutions are obtained in the cases of short and long conjugation length, respectively. From a linear combination of these cases an approximate solution for the general case is obtained. As an application of the model the influence of a static electric field on the electron-hole overlap integral and exciton energy is considered.

Particle localization and hyperuniformity of polymer-grafted nanoparticle materials

Energy Technology Data Exchange (ETDEWEB)

Chremos, Alexandros [Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD (United States); Douglas, Jack F.

2017-05-15

The properties of materials largely reflect the degree and character of the localization of the molecules comprising them so that the study and characterization of particle localization has central significance in both fundamental science and material design. Soft materials are often comprised of deformable molecules and many of their unique properties derive from the distinct nature of particle localization. We study localization in a model material composed of soft particles, hard nanoparticles with grafted layers of polymers, where the molecular characteristics of the grafted layers allow us to ''tune'' the softness of their interactions. Soft particles are particular interesting because spatial localization can occur such that density fluctuations on large length scales are suppressed, while the material is disordered at intermediate length scales; such materials are called ''disordered hyperuniform''. We use molecular dynamics simulation to study a liquid composed of polymer-grafted nanoparticles (GNP), which exhibit a reversible self-assembly into dynamic polymeric GNP structures below a temperature threshold, suggesting a liquid-gel transition. We calculate a number of spatial and temporal correlations and we find a significant suppression of density fluctuations upon cooling at large length scales, making these materials promising for the practical fabrication of ''hyperuniform'' materials. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Toxicity of inhaled {sup 238}PuO{sub 2} in Beagle dogs: A. Monodisperse 1.5 {mu}m AMAD particles. B. Monodisperse 3.0 {mu}m particles. XV

Energy Technology Data Exchange (ETDEWEB)

Mewhinney, J A; Gillett, N A; Muggenburg, B A; Hahn, F F; Diel, J H; Mauderly, J L; Boecker, B B; McClellan, R O

1988-12-01

Beagle dogs inhaled one of two sizes of monodisperse aerosols of {sup 238}PuO{sub 2} that resulted in graded levels of {sup 238}Pu in the lung. All dogs are being studied for their life span. One hundred and thirty-seven dogs that had initial lung burdens ranging from 0.01 to 1.5 {mu}Ci {sup 238}Pu/kg body weight (0.37 to 56 kBq/kg) have died, 8 with radiation pneumonitis and pulmonary fibrosis, 8 with lung tumors, 88 with bone tumors, 10 with liver tumors, and 25 of miscellaneous causes. Eighteen control dogs have died. Observations are being continued on 8 exposed and 6 control dogs alive at 4577-5274 days after exposure. (author)

Restrictions in Model Reduction for Polymer Chain Models in Dissipative Particle Dynamics

KAUST Repository

Moreno Chaparro, Nicolas

2014-06-06

We model high molecular weight homopolymers in semidilute concentration via Dissipative Particle Dynamics (DPD). We show that in model reduction methodologies for polymers it is not enough to preserve system properties (i.e., density ρ, pressure p, temperature T, radial distribution function g(r)) but preserving also the characteristic shape and length scale of the polymer chain model is necessary. In this work we apply a DPD-model-reduction methodology for linear polymers recently proposed; and demonstrate why the applicability of this methodology is limited upto certain maximum polymer length, and not suitable for solvent coarse graining.

Restrictions in Model Reduction for Polymer Chain Models in Dissipative Particle Dynamics

KAUST Repository

Moreno Chaparro, Nicolas; Nunes, Suzana Pereira; Calo, Victor M.

2014-01-01

We model high molecular weight homopolymers in semidilute concentration via Dissipative Particle Dynamics (DPD). We show that in model reduction methodologies for polymers it is not enough to preserve system properties (i.e., density ρ, pressure p, temperature T, radial distribution function g(r)) but preserving also the characteristic shape and length scale of the polymer chain model is necessary. In this work we apply a DPD-model-reduction methodology for linear polymers recently proposed; and demonstrate why the applicability of this methodology is limited upto certain maximum polymer length, and not suitable for solvent coarse graining.

Unique morphology of dispersed clay particles in a polymer nanocomposite

CSIR Research Space (South Africa)

Malwela, T

2011-02-01

Full Text Available This communication reports a unique morphology of dispersed clay particles in a polymer nanocomposite. A nanocomposite of poly[butylene succinate)-co-adipate] (PBSA) with 3 wt% of organically modified montmorillonite was prepared by melt...

Optical properties of monodispersive FePt nanoparticle films

Energy Technology Data Exchange (ETDEWEB)

Lee, S.J.; Lo, C.C.H. [Ames Laboratory, Iowa State University, Ames, IA 50011 (United States); Yu, A.C.C. [Sony Corporation, Sendai Technology Center, 3-4-1 Sakuragi, Miyagi 985-0842 (Japan); Fan, M. [Center for Sustainable Environmental Technologies, Iowa State University, Ames, IA 50011 (United States)

2004-10-01

The optical properties of monodispersive FePt nanoparticle films were investigated using spectroscopic ellipsometry in the energy range of 1.5 to 5.5 eV. The monodispersive FePt nanoparticle film was stabilized on a Si substrate by means of an organosilane coupling film, resulting in the formation of a (Si/SiO{sub 2}/APTS/FePt nanoparticles monolayer) structure. Multilayer optical models were employed to study the contribution of the FePt nanoparticles to the measured optical properties of the monodispersive FePt nanoparticle film, and to estimate the optical properties of the FePt nanoparticle layer. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Agglomerated polymer monoliths with bimetallic nano-particles as flow-through micro-reactors

International Nuclear Information System (INIS)

Floris, P.; Twamley, B.; Nesterenko, P.N.; Paull, B.; Connolly, D.

2012-01-01

Polymer monoliths in capillary format have been prepared as solid supports for the immobilisation of platinum/palladium bimetallic nano-flowers. Optimum surface coverage of nano-flowers was realised by photografting the monoliths with vinyl azlactone followed by amination with ethylenediamine prior to nano-particle immobilisation. Field emission SEM imaging was used as a characterisation tool for evaluating nano-particle coverage, together with BET surface area analysis to probe the effect of nano-particle immobilisation upon monolith morphology. Ion exchange chromatography was also used to confirm the nature of the covalent attachment of nano-flowers on the monolithic surface. In addition, EDX and ICP analyses were used to quantify platinum and palladium on modified polymer monoliths. Finally the catalytic properties of immobilised bimetallic Pd/Pt nano-flowers were evaluated in flow-through mode, exploiting the porous interconnected flow-paths present in the prepared monoliths (pore diameter ∼ 1-2 μm). Specifically, the reduction of Fe (III) to Fe (II) and the oxidation of NADH to NAD+ were selected as model redox reactions. The use of a porous polymer monolith as an immobilisation substrate (rather than aminated micro-spheres) eliminated the need for a centrifugation step after the reaction. (author)

Microwave Synthesized Monodisperse CdS Spheres of Different Size and Color for Solar Cell Applications

Directory of Open Access Journals (Sweden)

Carlos A. Rodríguez-Castañeda

2015-01-01

Full Text Available Monodisperse CdS spheres of size of 40 to 140 nm were obtained by microwave heating from basic solutions. It is observed that larger CdS spheres were formed at lower solution pH (8.4–8.8 and smaller ones at higher solution pH (10.8–11.3. The color of CdS products changed with solution pH and reaction temperature; those synthesized at lower pH and temperature were of green-yellow color, whereas those formed at higher pH and temperature were of orange-yellow color. A good photovoltage was observed in CdS:poly(3-hexylthiophene solar cells with spherical CdS particles. This is due to the good dispersion of CdS nanoparticles in P3HT solution that led to a large interface area between the organic and inorganic semiconductors. Higher photocurrent density was obtained in green-yellow CdS particles of lower defect density. The efficient microwave chemistry accelerated the hydrolysis of thiourea in pH lower than 9 and produced monodisperse spherical CdS nanoparticles suitable for solar cell applications.

Advances in Biomagnetic Interfacing Concepts Derived from Polymer-Magnetic Particle Complexes

National Research Council Canada - National Science Library

Riffle, Judy S

2005-01-01

Our research on the development and characterization of magnetic nanoparticle-polymer complexes for tile project period 6/1/03-12/31/04 has yielded approximately 10-nm diameter cobalt particles coated...

Deposition and detection of particles during integrated circuit manufacturing

NARCIS (Netherlands)

Wali, F.; Knotter, D. Martin; Kelly, John J.; Kuper, F.G.

2006-01-01

Abstract—Deposition mechanism of silica particles on silicon wafers was investigated by depositing specially prepared mono-dispersed particles (mean diameter = 330 nm). To measure particles of the size below the detection limit of our particle measurement tools, silica particles with luminance core

Preparation and drug-loading properties of Fe{sub 3}O{sub 4}/Poly(styrene-co-acrylic acid) magnetic polymer nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Lu, Wensheng [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039 (China); Coordination Chemistry Institute, School of Chemistry and Chemical Engineering and Life Science, Chaohu University, Chaohu 238000 (China); Shen, Yuhua, E-mail: s_yuhua@163.com [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039 (China); Xie, Anjian [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039 (China); Zhang, Weiqiang [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039 (China); Coordination Chemistry Institute, School of Chemistry and Chemical Engineering and Life Science, Chaohu University, Chaohu 238000 (China)

2013-11-15

Fe{sub 3}O{sub 4}/poly(styrene-co-acrylic acid) magnetic polymer nanocomposites were synthesized by the dispersion polymerization method using styrene as hard monomer, acrylic acid as functional monomer, Fe{sub 3}O{sub 4} nanoparticles modified with oleic acid as core, and poly(styrene-co-acrylic acid) as shell. Drug-loading properties of magnetic polymer nanocomposites with curcumin as a model drug were also studied. The results indicated that magnetic polymer nanocomposites with monodisperse were obtained, the particle size distribution was 50–120 nm, and the average size was about 100 nm. The contents of poly(styrene-co-acrylic acid) and Fe{sub 3}O{sub 4} nanoparticles in magnetic polymer nanocomposites were 74% and 24.7%, respectively. The drug-loading capacity and entrapment efficiency were 2.5% and 44.4%, respectively. The saturation magnetization of magnetic polymer nanocomposites at 300 K was 20.2 emu/g without coercivity and remanence. The as-prepared magnetic polymer nanocomposites have not only lots of functional carboxyl groups but also stronger magnetic response, which might have potential applications in drug carrier and targeted drug release.

Laser ablation synthesis of monodispersed magnetic alloy nanoparticles

International Nuclear Information System (INIS)

Seto, Takafumi; Koga, Kenji; Akinaga, Hiroyuki; Takano, Fumiyoshi; Orii, Takaaki; Hirasawa, Makoto

2006-01-01

Monodispersed CoPt alloy nanoparticles were synthesized by a pulsed laser ablation (PLA) technique coupled with a low-pressure operating differential mobility analyzer (LP-DMA). The CoPt alloy nanoparticles were generated by laser ablating a solid Co-Pt target. In CoPt alloy nanoparticles synthesized from a target with a Co composition of 75 at%, the nanoparticle surfaces were covered by an oxide layer and exhibited a core-shell structure. In contrast, no shell was observed in particles generated from a target with a Co:Pt ratio of 50:50 at%. According to an EDX analysis, the compositions of the individual nanoparticles were almost the same as that of the target material. Finally, the magnetic hysteresis loops of the CoPt alloy nanoparticles exhibited ferromagnetism

Laser ablation synthesis of monodispersed magnetic alloy nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Seto, Takafumi, E-mail: t.seto@aist.go.jp; Koga, Kenji; Akinaga, Hiroyuki; Takano, Fumiyoshi; Orii, Takaaki; Hirasawa, Makoto [National Institute of Advanced Industrial Science and Technology (AIST), Research Consortium for Synthetic Nano-Function Materials Project (SYNAF) (Japan)

2006-08-15

Monodispersed CoPt alloy nanoparticles were synthesized by a pulsed laser ablation (PLA) technique coupled with a low-pressure operating differential mobility analyzer (LP-DMA). The CoPt alloy nanoparticles were generated by laser ablating a solid Co-Pt target. In CoPt alloy nanoparticles synthesized from a target with a Co composition of 75 at%, the nanoparticle surfaces were covered by an oxide layer and exhibited a core-shell structure. In contrast, no shell was observed in particles generated from a target with a Co:Pt ratio of 50:50 at%. According to an EDX analysis, the compositions of the individual nanoparticles were almost the same as that of the target material. Finally, the magnetic hysteresis loops of the CoPt alloy nanoparticles exhibited ferromagnetism.

Design of sustained release fine particles using two-step mechanical powder processing: particle shape modification of drug crystals and dry particle coating with polymer nanoparticle agglomerate.

Science.gov (United States)

Kondo, Keita; Ito, Natsuki; Niwa, Toshiyuki; Danjo, Kazumi

2013-09-10

We attempted to prepare sustained release fine particles using a two-step mechanical powder processing method; particle-shape modification and dry particle coating. First, particle shape of bulk drug was modified by mechanical treatment to yield drug crystals suitable for the coating process. Drug crystals became more rounded with increasing rotation speed, which demonstrates that powerful mechanical stress yields spherical drug crystals with narrow size distribution. This process is the result of destruction, granulation and refinement of drug crystals. Second, the modified drug particles and polymer coating powder were mechanically treated to prepare composite particles. Polymer nanoparticle agglomerate obtained by drying poly(meth)acrylate aqueous dispersion was used as a coating powder. The porous nanoparticle agglomerate has superior coating performance, because it is completely deagglomerated under mechanical stress to form fine fragments that act as guest particles. As a result, spherical drug crystals treated with porous agglomerate were effectively coated by poly(meth)acrylate powder, showing sustained release after curing. From these findings, particle-shape modification of drug crystals and dry particle coating with nanoparticle agglomerate using a mechanical powder processor is expected as an innovative technique for preparing controlled-release coated particles having high drug content and size smaller than 100 μm. Copyright © 2013 Elsevier B.V. All rights reserved.

Behaviour of non-spherical particles in the TSI aerodynamic particle sizer

International Nuclear Information System (INIS)

Marshall, I.A.

1991-02-01

The TSI Aerodynamic Particle Sizer (APS33B) is a real-time monitor which is capable of measuring aerosols in terms of this most relevant size parameter for the assessment of occupational risk. The influence of particle shape on APS33B performance has been investigated using a range of monodisperse, regular-shaped and non-porous solid particles in the size range from about 6 to 14 μm aerodynamic diameter. (author)

Influence of nanoclay particles modification by polyester-amide hyperbranched polymer on the corrosion protective performance of the epoxy nanocomposite

International Nuclear Information System (INIS)

Ganjaee Sari, M.; Ramezanzadeh, B.; Shahbazi, M.; Pakdel, A.S.

2015-01-01

Highlights: • Nanoclay particles were modified with polyester-amide hyperbranched polymer. • Epoxy/clay nanocomposites were prepared using modified clay particles. • Surface modification enhanced the clay particles exfoliation properties. • Surface modified clay particles enhanced corrosion resistance of the epoxy coating. - Abstract: Surface modification of nanoclay particles was carried out by various amounts of polyester-amide hyperbranched polymer (HBP). Thermal gravimetric analysis and X-ray diffraction analysis were performed to estimate the efficiency of the HPB grafting on the clay particles. Epoxy/clay nanocomposites were prepared by addition of 1 wt.% unmodified and modified clays. The corrosion protection properties of the nanocomposites were evaluated by electrochemical impedance spectroscopy (EIS). Results revealed that surface modification of the clay particles by HBP caused significant enhancement of the epoxy coating corrosion resistance especially when the ‘polymer/clay’ ratios were 10/1 and 5/1

Molecularly imprinted polymer beads for nicotine recognition prepared by RAFT precipitation polymerization: a step forward towards multifunctionalities

DEFF Research Database (Denmark)

Zhou, Tongchang; Jørgensen, Lars; Mattebjerg, Maria Ahlm

2014-01-01

A nicotine imprinted polymer was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization using methacrylic acid (MAA) as a functional monomer. The resulting molecularly imprinted polymers were monodispersed beads with an average diameter of 1.55 mm. The molecular...... selectivity of the imprinted polymer beads was evaluated by studying the uptake of nicotine and its structural analogs by the polymer beads. Equilibrium binding results indicate that the amount of nicotine bound to the imprinted polymer beads is significantly higher than that bound to the nonimprinted polymer...

Molecular identification of polymers and anthropogenic particles extracted from oceanic water and fish stomach - A Raman micro-spectroscopy study.

Science.gov (United States)

Ghosal, Sutapa; Chen, Michael; Wagner, Jeff; Wang, Zhong-Min; Wall, Stephen

2018-02-01

Pacific Ocean trawl samples, stomach contents of laboratory-raised fish as well as fish from the subtropical gyres were analyzed by Raman micro-spectroscopy (RMS) to identify polymer residues and any detectable persistent organic pollutants (POP). The goal was to access specific molecular information at the individual particle level in order to identify polymer debris in the natural environment. The identification process was aided by a laboratory generated automated fluorescence removal algorithm. Pacific Ocean trawl samples of plastic debris associated with fish collection sites were analyzed to determine the types of polymers commonly present. Subsequently, stomach contents of fish from these locations were analyzed for ingested polymer debris. Extraction of polymer debris from fish stomach using KOH versus ultrapure water were evaluated to determine the optimal method of extraction. Pulsed ultrasonic extraction in ultrapure water was determined to be the method of choice for extraction with minimal chemical intrusion. The Pacific Ocean trawl samples yielded primarily polyethylene (PE) and polypropylene (PP) particles >1 mm, PE being the most prevalent type. Additional microplastic residues (1 mm - 10 μm) extracted by filtration, included a polystyrene (PS) particle in addition to PE and PP. Flame retardant, deca-BDE was tentatively identified on some of the PP trawl particles. Polymer residues were also extracted from the stomachs of Atlantic and Pacific Ocean fish. Two types of polymer related debris were identified in the Atlantic Ocean fish: (1) polymer fragments and (2) fragments with combined polymer and fatty acid signatures. In terms of polymer fragments, only PE and PP were detected in the fish stomachs from both locations. A variety of particles were extracted from oceanic fish as potential plastic pieces based on optical examination. However, subsequent RMS examination identified them as various non-plastic fragments, highlighting the importance

Colloidal polymer particles as catalyst carriers and phase transfer agents in multiphasic hydroformylation reactions.

Science.gov (United States)

Peral, D; Stehl, D; Bibouche, B; Yu, H; Mardoukh, J; Schomäcker, R; Klitzing, R von; Vogt, D

2018-03-01

Colloidal particles have been used to covalently bind ligands for the heterogenization of homogeneous catalysts. The replacement of the covalent bonds by electrostatic interactions between particles and the catalyst could preserve the selectivity of a truly homogeneous catalytic process. Functionalized polymer particles with trimethylammonium moieties, dispersed in water, with a hydrophobic core and a hydrophilic shell have been synthesized by emulsion polymerization and have been thoroughly characterized. The ability of the particles with different monomer compositions to act as catalyst carriers has been studied. Finally, the colloidal dispersions have been applied as phase transfer agents in the multiphasic rhodium-catalyzed hydroformylation of 1-octene. The hydrodynamic radius of the particles has been shown to be around 100 nm, and a core-shell structure could be observed by atomic force microscopy. The polymer particles were proven to act as carriers for the water-soluble hydroformylation catalyst, due to electrostatic interaction between the functionalized particles bearing ammonium groups and the sulfonated ligands of the catalyst. The particles were stable under the hydroformylation conditions and the aqueous catalyst phase could be recycled three times. Copyright © 2017 Elsevier Inc. All rights reserved.

Tailored synthesis of monodispersed nano/submicron porous silicon oxycarbide (SiOC) spheres with improved Li-storage performance as an anode material for Li-ion batteries

Science.gov (United States)

Shi, Huimin; Yuan, Anbao; Xu, Jiaqiang

2017-10-01

A spherical silicon oxycarbide (SiOC) material (monodispersed nano/submicron porous SiOC spheres) is successfully synthesized via a specially designed synthetic strategy involving pyrolysis of phenyltriethoxysilane derived pre-ceramic polymer spheres at 900 °C. In order to prevent sintering of the pre-ceramic polymer spheres upon heating, a given amount of hollow porous SiO2 nanobelts which are separately prepared from tetraethyl orthosilicate with CuO nanobelts as templates are introduced into the pre-ceramic polymer spheres before pyrolysis. This material is investigated as an anode for lithium-ion batteries in comparison with the large-size bulk SiOC material synthesized under the similar conditions but without hollow SiO2 nanobelts. The maximum reversible specific capacity of ca. 900 mAh g-1 is delivered at the current density of 100 mA g-1 and ca. 98% of the initial capacity is remained after 100 cycles at 100 mA g-1 for the SiOC spheres material, which are much superior to the bulk SiOC material. The improved lithium storage performance in terms of specific capacity and cyclability is attributed to its particular morphology of monodisperse nano/submicron porous spheres as well as its modified composition and microstructure. This SiOC material has higher Li-storage activity and better stability against volume expansion during repeated lithiation and delithiation cycling.

Electromechanical characterization of individual micron-sized metal coated polymer particles

Energy Technology Data Exchange (ETDEWEB)

Bazilchuk, Molly; Kristiansen, Helge [Department of Structural Engineering, Norwegian University of Science and Technology, Trondheim 7491 (Norway); Conpart AS, Skjetten 2013 (Norway); Pettersen, Sigurd Rolland; Zhang, Zhiliang; He, Jianying, E-mail: jianying.he@ntnu.no [Department of Structural Engineering, Norwegian University of Science and Technology, Trondheim 7491 (Norway)

2016-06-28

Micron-sized polymer particles with nanoscale metal coatings are essential in conductive adhesives for electronics assembly. The particles function in a compressed state in the adhesives. The link between mechanical properties and electrical conductivity is thus of the utmost importance in the formation of good electrical contact. A custom flat punch set-up based on nanoindentation has been developed to simultaneously deform and electrically probe individual particles. The set-up has a sufficiently low internal resistance to allow the measurement of sub-Ohm contact resistances. Additionally, the set-up can capture mechanical failure of the particles. Combining this data yields a fundamental understanding of contact behavior. We demonstrate that this method can clearly distinguish between particles of different sizes, with different thicknesses of metal coating, and different metallization schemes. The technique provides good repeatability and physical insight into the behavior of these particles that can guide adhesive design and the optimization of bonding processes.

Electromechanical characterization of individual micron-sized metal coated polymer particles

International Nuclear Information System (INIS)

Bazilchuk, Molly; Kristiansen, Helge; Pettersen, Sigurd Rolland; Zhang, Zhiliang; He, Jianying

2016-01-01

Micron-sized polymer particles with nanoscale metal coatings are essential in conductive adhesives for electronics assembly. The particles function in a compressed state in the adhesives. The link between mechanical properties and electrical conductivity is thus of the utmost importance in the formation of good electrical contact. A custom flat punch set-up based on nanoindentation has been developed to simultaneously deform and electrically probe individual particles. The set-up has a sufficiently low internal resistance to allow the measurement of sub-Ohm contact resistances. Additionally, the set-up can capture mechanical failure of the particles. Combining this data yields a fundamental understanding of contact behavior. We demonstrate that this method can clearly distinguish between particles of different sizes, with different thicknesses of metal coating, and different metallization schemes. The technique provides good repeatability and physical insight into the behavior of these particles that can guide adhesive design and the optimization of bonding processes.

Multiscale Micromechanical Modeling of Polymer/Clay Nanocomposites and the Effective Clay Particle

Science.gov (United States)

Sheng, Nuo; Boyce, Mary C.; Parks, David M.; Manovitch, Oleg; Rutledge, Gregory C.; Lee, Hojun; McKinley, Gareth H.

2003-03-01

Polymer/clay nanocomposites have been observed to exhibit enhanced mechanical properties at low weight fractions (Wp) of clay. Continuum-based composite modeling reveals that the enhanced properties are strongly dependent on particular features of the second-phase ¡°particles¡+/-; in particular, the particle volume fraction (fp), the particle aspect ratio (L/t), and the ratio of particle mechanical properties to those of the matrix. However, these important aspects of as-processed nanoclay composites have yet to be consistently and accurately defined. A multiscale modeling strategy was developed to account for the hierarchical morphology of the nanocomposite: at a lengthscale of thousands of microns, the structure is one of high aspect ratio particles within a matrix; at the lengthscale of microns, the clay particle structure is either (a) exfoliated clay sheets of nanometer level thickness or (b) stacks of parallel clay sheets separated from one another by interlayer galleries of nanometer level height. Here, quantitative structural parameters extracted from XRD patterns and TEM micrographs are used to determine geometric features of the as-processed clay ¡°particles¡+/-, including L/t and the ratio of fp to Wp. These geometric features, together with estimates of silicate lamina stiffness obtained from molecular dynamics simulations, provide a basis for modeling effective mechanical properties of the clay particle. The structure-based predictions of the macroscopic elastic modulus of the nanocomposite as a function of clay weight fraction are in excellent agreement with experimental data. The adopted methodology offers promise for study of related properties in polymer/clay nanocomposites.

Production of micron-sized polymer particles for additive manufacturing by melt emulsification

Energy Technology Data Exchange (ETDEWEB)

Fanselow, Stephanie; Schmidt, Jochen; Wirth, Karl-Ernst; Peukert, Wolfgang, E-mail: Wolfgang.Peukert@fau.de [Institute of Particle Technology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstrasse 4, 91058 Erlangen (Germany)

2016-03-09

Melt emulsification is an advanced top-down approach that permits to produce spherical particles and thus widens the availability of polymer feed materials for additive manufacturing. In the process the polymer is molten in a continuous phase and droplet breakup is realized in a rotor-stator-device. The stabilization of the newly formed surfaces is quite challenging. Therefore, a new method to identify an appropriate emulsifier by measuring the interfacial tension between the polymer and continuous phase using a high pressure / high temperature cell is presented. The obtained powders are characterized by scanning electron microscopy (SEM) and by a Zimmermann tensile strength tester to determine the powder flowability. The processability of the polymer powders for additive manufacturing is investigated and demonstrated by building single layers by laser beam melting.

Effects of polyacrylic acid additive on barium sulfate particle morphology

Energy Technology Data Exchange (ETDEWEB)

Li, Jie; Liu, Dandan; Jiang, Hongkun; Wang, Jun; Jing, Xiaoyan; Chen, Rongrong [Key Laboratory of Superlight Material and Surface Technology of Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Zhu, Wenting [Department of Gastroenterology, Harbin Medical University Cancer Hospital, Harbin 150081 (China); Han, Shihui [Key Laboratory of Superlight Material and Surface Technology of Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Li, Wanyou [College of Power and Energy Engineering, Harbin Engineering University, Harbin 150001 (China); Wei, Hao, E-mail: weihao7512@126.com [Key Laboratory of Superlight Material and Surface Technology of Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); College of Power and Energy Engineering, Harbin Engineering University, Harbin 150001 (China)

2016-06-01

In this paper, polyacrylic acid (PAA) was used as a growth modifier to control micron-sized barium sulfate particles via a simple precipitation reaction between sodium sulfate and barium chloride at ambient temperature. The barium sulfate particles were exhibited various morphologies, such as monodisperse spheres, ellipsoids, rose-like aggregates, etc. To better understand the formation mechanisms of the various morphologies of these particles, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermo-gravimetric analysis (TGA) were employed. It was found that the PAA concentration, pH, and Ba{sup 2+} and SO{sub 4}{sup 2−} ions concentrations were the most important parameters controlling the morphology of the BaSO{sub 4} particles. These parameters affected the BaSO{sub 4} morphology by influencing the interactions between the PAA carboxyl groups and inorganic ions and the conformation change of the PAA molecular chains. Moreover, this work attempts to provide a preliminary understanding of the formation of the spherical BaSO{sub 4} particles with the randomly coiled conformation of the polymer. - Highlights: • Polyacrylic acid (PAA) was used as a growth modifier to control micron-sized BaSO{sub 4} particles. • The PAA/BaSO{sub 4} particles were exhibited various morphologies. • Provide a preliminary understanding of the formation mechanism of BaSO{sub 4} particles.

Nonthermal plasma synthesis of size-controlled, monodisperse, freestanding germanium nanocrystals

International Nuclear Information System (INIS)

Gresback, Ryan; Holman, Zachary; Kortshagen, Uwe

2007-01-01

Germanium nanocrystals may be of interest for a variety of electronic and optoelectronic applications including photovoltaics, primarily due to the tunability of their band gap from the infrared into the visible range of the spectrum. This letter discusses the synthesis of monodisperse germanium nanocrystals via a nonthermal plasma approach which allows for precise control of the nanocrystal size. Germanium crystals are synthesized from germanium tetrachloride and hydrogen entrained in an argon background gas. The crystal size can be varied between 4 and 50 nm by changing the residence times of crystals in the plasma between ∼30 and 440 ms. Adjusting the plasma power enables one to synthesize fully amorphous or fully crystalline particles with otherwise similar properties

Design and scale-up of a semi-industrial downer-reactor for the rounding of irregular polymer particles

Energy Technology Data Exchange (ETDEWEB)

Sachs, Marius; Schmidt, Jochen; Peukert, Wolfgang; Wirth, Karl-Ernst [Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Particle Technology, Cauerstr. 4, D-91058 Erlangen (Germany)

2016-03-09

The recent development of rapid prototyping technologies towards additive manufacturing reveals some major drawbacks of processes such as laser beam melting (LBM). This contribution focuses on the lack of suitable polymer material with a fine particle size and good flowability. Polymer particles obtained by a wet grinding process 1 are treated in a heated downer reactor. This treatment changes the particles’ morphology from a chiselled state towards a spherical form by surface tension forces in a molten state 2 and leads to an improved flowability. To reach the required amount of rounded polymer powder, a downer reactor in semi-industrial scale has been established and will be characterized in this article. For the purpose of particle rounding it is necessary to avoid contact of molten particles with each other and with the hot reactor walls. Furthermore, the heat distribution has been investigated as one of the key parameters of the process. Finally, a proof of concept by rounding wet grinded PBT material was successfully conducted. The product was examined to obtain data about a change in particle size and flowability.

Radiation crosslinking of polymers with segregated metallic particles. Final report, June 1, 1971--September 30, 1973

International Nuclear Information System (INIS)

Corneliussen, R.D.; Kamel, I.; Kusy, R.P.

1973-01-01

Through the past four years of research, a new approach to fabricating conductive polymer/metal composites has been developed. This approach consists of compacting mixtures of polymer and metal powders and then stabilizing the composite through radiation-induced crosslinking. The result is a mechanically strong, conductive materials consisting of two intertwining networks. One is a massive network consisting of fused crosslinked, large (greater than 100 μ) polymer particles while the other is a fine network of small, metallic particles (greater than 10 μ). Nine different systems including crystalline, amorphous, and rubbery polymers were studied. Processing at this time is limited to compression molding in a closed die because of network stability problems. Costs for processing were estimated at about $6.00/lb compared to $50.00 and up for commercial material based on random networks. (U.S.)

Intrinsic speckle noise in in-line particle holography due to polydisperse and continuous particle sizes

Science.gov (United States)

Edwards, Philip J.; Hobson, Peter R.; Rodgers, G. J.

2000-08-01

In-line particle holography is subject to image deterioration due to intrinsic speckle noise. The resulting reduction in the signal to noise ratio (SNR) of the replayed image can become critical for applications such as holographic particle velocimetry (HPV) and 3D visualisation of marine plankton. Work has been done to extend the mono-disperse model relevant to HPV to include poly-disperse particle fields appropriate for the visualisation of marine plankton. Continuous and discrete particle fields are both considered. It is found that random walk statistics still apply for the poly-disperse case. The speckle field is simply the summation of the individual speckle patters due to each scatter size. Therefor the characteristic speckle parameter (which encompasses particle diameter, concentration and sample depth) is alos just the summation of the individual speckle parameters. This reduces the SNR calculation to the same form as for the mono-disperse case. For the continuous situation three distributions, power, exponential and Gaussian are discussed with the resulting SNR calcuated. The work presented here was performed as part of the Holomar project to produce a working underwater holographic camera for recording plankton.

Synthesis of monodisperse silica microspheres and modification with diazoresin for mixed-mode ultra high performance liquid chromatography separations.

Science.gov (United States)

Cong, Hailin; Yu, Bing; Tian, Chao; Zhang, Shuai; Yuan, Hua

2017-11-01

Monodisperse silica particles with average diameters of 1.9-2.9 μm were synthesized by a modified Stöber method, in which tetraethyl orthosilicate was continuously supplied to the reaction mixture containing KCl electrolyte, water, ethanol, and ammonia. The obtained silica particles were modified by self-assembly with positively charged photosensitive diazoresin on the surface. After treatment with ultraviolet light, the ionic bonding between silica and diazoresin was converted into covalent bonding through a unique photochemistry reaction of diazoresin. Depending on the chemical structure of diazoresin and mobile phase composition, the diazoresin-modified silica stationary phase showed different separation mechanisms, including reversed phase and hydrophilic interactions. Therefore, a variety of baseline separation of benzene analogues and organic acids was achieved by using the diazoresin-modified silica particles as packing materials in ultra high performance liquid chromatography. According to the π-π interactional difference between carbon rings of fullerenes and benzene rings of diazoresin, C 60 and C 70 were also well separated by ultra-high performance liquid chromatography. Because it has a small size, the ∼2.5 μm monodisperse diazoresin-modified silica stationary phase shows ultra-high efficiency compared with the commercial C 18 -silica high-performance liquid chromatography stationary phase with average diameters of ∼5 μm. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Removal of toxic uranium from synthetic nuclear power reactor effluents using uranyl ion imprinted polymer particles.

Science.gov (United States)

Preetha, Chandrika Ravindran; Gladis, Joseph Mary; Rao, Talasila Prasada; Venkateswaran, Gopala

2006-05-01

Major quantities of uranium find use as nuclear fuel in nuclear power reactors. In view of the extreme toxicity of uranium and consequent stringent limits fixed by WHO and various national governments, it is essential to remove uranium from nuclear power reactor effluents before discharge into environment. Ion imprinted polymer (IIP) materials have traditionally been used for the recovery of uranium from dilute aqueous solutions prior to detection or from seawater. We now describe the use of IIP materials for selective removal of uranium from a typical synthetic nuclear power reactor effluent. The IIP materials were prepared for uranyl ion (imprint ion) by forming binary salicylaldoxime (SALO) or 4-vinylpyridine (VP) or ternary SALO-VP complexes in 2-methoxyethanol (porogen) and copolymerizing in the presence of styrene (monomer), divinylbenzene (cross-linking monomer), and 2,2'-azobisisobutyronitrile (initiator). The resulting materials were then ground and sieved to obtain unleached polymer particles. Leached IIP particles were obtained by leaching the imprint ions with 6.0 M HCl. Control polymer particles were also prepared analogously without the imprint ion. The IIP particles obtained with ternary complex alone gave quantitative removal of uranyl ion in the pH range 3.5-5.0 with as low as 0.08 g. The retention capacity of uranyl IIP particles was found to be 98.50 mg/g of polymer. The present study successfully demonstrates the feasibility of removing uranyl ions selectively in the range 5 microg - 300 mg present in 500 mL of synthetic nuclear power reactor effluent containing a host of other inorganic species.

Hierarchical ZnO particles grafting by fluorocarbon polymer derivative: Preparation and superhydrophobic behavior

Energy Technology Data Exchange (ETDEWEB)

Gao, Dahai; Jia, Mengqiu, E-mail: jiamq@mail.buct.edu.cn

2015-07-15

Graphical abstract: - Highlights: • The hierarchical particles were prepared by a simple, mild hydrothermal process. • The obtained “chestnut” ZnO particles show dual-scale morphology with high roughness. • FEVE derivative was creatively imported to graft onto hierarchical particles. • Superhydrophobic surfaces were obtained, on which the contact angles surpass 150°. • A special model was proposed to explain the wetting state in this work. - Abstract: Superhydrophobic surfaces on the basis of hierarchical ZnO particles grafted by fluoroethylene-vinylether (FEVE) polymer derivative were prepared using a facile, mild and low-cost method. X-ray diffraction (XRD) and scanning electron microscope (SEM) revealed that the resulting ZnO particles via hydrothermal process exhibit micro–nano dual-scale morphology with high purity under a suitable surfactant amount and alkali concentration. The grafting of FEVE derivative was confirmed by Fourier transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectrometer (EDS), suggesting that hierarchical surface of ZnO particles was an imported monomolecular layer of fluorocarbon polymer. The obtained surface fabricated by drop-casting shows considerably high contact angle and good resistance to water immersion. The wetting behavior in this work was furthermore analyzed by theoretical wetting model. This work demonstrates that the sufficient low-wettable surface and high roughness both take a vital role in the superhydrophobic behavior.

Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles

Directory of Open Access Journals (Sweden)

Sumeet Kumar

2015-02-01

Full Text Available In the present study, monodispersed CeO2 nanoparticles (NPs of size 8.5 ± 1.0, 11.4 ± 1.0 and 15.4 ± 1.0 nm were synthesized using the sol-gel method. Size-dependent structural, optical and magnetic properties of as-prepared samples were investigated by X-ray diffraction (XRD, field emission scanning electron microscope (FE-SEM, high resolution transmission electron microscopy (HR-TEM, ultra-violet visible (UV-VIS spectroscopy, Raman spectroscopy and vibrating sample magnetometer (VSM measurements. The value of optical band gap is calculated for each particle size. The decrease in the value of optical band gap with increase of particle size may be attributed to the quantum confinement, which causes to produce localized states created by the oxygen vacancies due to the conversion of Ce4+ into Ce3+ at higher calcination temperature. The Raman spectra showed a peak at ∼461 cm-1 for the particle size 8.5 nm, which is attributed to the 1LO phonon mode. The shift in the Raman peak could be due to lattice strain developed due to variation in particle size. Weak ferromagnetism at room temperature is observed for each particle size. The values of saturation magnetization (Ms, coercivity (Hc and retentivity (Mr are increased with increase of particle size. The increase of Ms and Mr for larger particle size may be explained by increase of density of oxygen vacancies at higher calcination temperature. The latter causes high concentrations of Ce3+ ions activate more coupling between the individual magnetic moments of the Ce ions, leading to an increase of Ms value with the particle size. Moreover, the oxygen vacancies may also produce magnetic moment by polarizing spins of f electrons of cerium (Ce ions located around oxygen vacancies, which causes ferromagnetism in pure CeO2 samples.

Particle-in-a-box model of exciton absorption and electroabsorption in conjugated polymers

Science.gov (United States)

Pedersen, Thomas G.

2000-12-01

The recently proposed particle-in-a-box model of one-dimensional excitons in conjugated polymers is applied in calculations of optical absorption and electroabsorption spectra. It is demonstrated that for polymers of long conjugation length a superposition of single exciton resonances produces a line shape characterized by a square-root singularity in agreement with experimental spectra near the absorption edge. The effects of finite conjugation length on both absorption and electroabsorption spectra are analyzed.

Contribution to the study of particle resuspension kinetics during thermal degradation of polymers.

Science.gov (United States)

Ouf, F-X; Delcour, S; Azema, N; Coppalle, A; Ferry, L; Gensdarmes, F; Lopez-Cuesta, J-M; Niang, A; Pontreau, S; Yon, J

2013-04-15

Experimental results are reported on the resuspension of particles deposited on polymer samples representative of glove boxes used in the nuclear industry, under thermal degradation. A parametric study was carried out on the effects of heat flux, air flow rate, fuel type and particle size distribution. Small-scale experiments were conducted on 10 cm × 10 cm PolyMethyl MethAcrylate (PMMA) and PolyCarbonate (PC) samples covered with aluminium oxide particles with physical geometric diameters of 0.7 and 3.6 μm. It was observed for both polymer (fuel) samples that heat flux has no effect on the airborne release fraction (ARF), whereas particle size is a significant parameter. In the case of the PMMA sample, ARF values for 0.7 and 3.6 μm diameter particles range from 12.2% (± 6.2%) to 2.1% (± 0.6%), respectively, whereas the respective values for the PC sample range from 3.2% (± 0.8%) to 6.9% (± 3.9%). As the particle diameter increases, a significant decrease in particle release is observed for the PMMA sample, whereas an increase is observed for the PC sample. Furthermore, a peak airborne release rate is observed during the first instants of PMMA exposure to thermal stress. An empirical relationship has been proposed between the duration of this peak release and the external heat flux. Copyright © 2013 Elsevier B.V. All rights reserved.

Monodispersed MnO nanoparticles with epitaxial Mn{sub 3}O{sub 4} shells

Energy Technology Data Exchange (ETDEWEB)

Berkowitz, A E; Rodriguez, G F [Department of Physics, University of California, San Diego La Jolla, CA 92093 (United States); Hong, J I; Fullerton, E E [Center for Magnetic Recording Research, University of California-San Diego La Jolla, CA 92093 (United States); An, K; Hyeon, T [National Creative Research Initiative Center for Oxide Nanocrystalline Materials, Seoul National University, Seoul 151-744 (Korea, Republic of); Agarwal, N; Smith, D J [School of Materials and Department of Physics, Arizona State University, Tempe, AZ 85287 (United States)

2008-07-07

We report the microstructural and magnetic properties of monodispersed nanoparticles (NPs) of antiferromagnetic MnO (T{sub N} = 118 K), with epitaxial ferrimagnetic Mn{sub 3}O{sub 4} (T{sub C} = 43 K) shells. Above T{sub C}, an unusually large magnetization is present, produced by the uncompensated spins (UCSs) on the surface of the MnO particles. These spins impart a net anisotropy to the MnO particles that is approximately three orders of magnitude larger than the bulk value. As a result, an anomalously high blocking temperature is exhibited by the MnO particles, and finite coercivity and exchange bias are present above T{sub C}. When field cooled below T{sub C}, a strong exchange bias was established in the Mn{sub 3}O{sub 4} shells as a result of high net anisotropy of the MnO particles. A large coercivity was also observed. Models of several aspects of the behaviour of this unusual system emphasized the essential role of the UCSs on the surfaces of the MnO NPs.

EFFECT OF BODY SIZE ON BREATHING PATTERN AND FINE PARTICLE DEPOSITION IN CHILDREN

Science.gov (United States)

Inter-child variability in breathing patterns may contribute to variability in fine particle, lung deposition and morbidity in children associated with those particles. Fractional deposition (DF) of fine particles (2um monodisperse, carnauba wax particles) was measured in healthy...

Solid particle erosion of polymers and composites

Science.gov (United States)

Friedrich, K.; Almajid, A. A.

2014-05-01

After a general introduction to the subject of solid particle erosion of polymers and composites, the presentation focusses more specifically on the behavior of unidirectional carbon fiber (CF) reinforced polyetheretherketone (PEEK) composites under such loadings, using different impact conditions and erodents. The data were analyzed on the basis of a newly defined specific erosive wear rate, allowing a better comparison of erosion data achieved under various testing conditions. Characteristic wear mechanisms of the CF/PEEK composites consisted of fiber fracture, matrix cutting and plastic matrix deformation, the relative contribution of which depended on the impingement angles and the CF orientation. The highest wear rates were measured for impingement angles between 45 and 60°. Using abrasion resistant neat polymer films (in this case PEEK or thermoplastic polyurethane (TPU) ones) on the surface of a harder substrate (e.g. a CF/PEEK composite plate) resulted in much lower specific erosive wear rates. The use of such polymeric films can be considered as a possible method to protect composite surfaces from damage caused by minor impacts and erosion. In fact, they are nowadays already successfully applied as protections for wind energy rotor blades.

Localization of a polymer in random media: Relation to the localization of a quantum particle

International Nuclear Information System (INIS)

Shiferaw, Yohannes; Goldschmidt, Yadin Y.

2001-01-01

In this paper we consider in detail the connection between the problem of a polymer in a random medium and that of a quantum particle in a random potential. We are interested in a system of finite volume where the polymer is known to be localized inside a low minimum of the potential. We show how the end-to-end distance of a polymer that is free to move can be obtained from the density of states of the quantum particle using extreme value statistics. We give a physical interpretation to the recently discovered one-step replica-symmetry-breaking solution for the polymer [Phys. Rev. E 61, 1729 (2000)] in terms of the statistics of localized tail states. Numerical solutions of the variational equations for chains of different length are performed and compared with quenched averages computed directly by using the eigenfunctions and eigenenergies of the Schro''dinger equation for a particle in a one-dimensional random potential. The quantities investigated are the radius of gyration of a free Gaussian chain, its mean square distance from the origin and the end-to-end distance of a tethered chain. The probability distribution for the position of the chain is also investigated. The glassiness of the system is explained and is estimated from the variance of the measured quantities

Monodisperse colloidal spheres for (Y,Eu2O3 red-emitting phosphors: establishment of processing window and size-dependent luminescence behavior

Directory of Open Access Journals (Sweden)

Qi Zhu, Ji-Guang Li, Xiaodong Li, Xudong Sun and Yoshio Sakka

2011-01-01

Full Text Available The urea-based homogeneous precipitation method was introduced in the preparation of monodisperse colloidal spheres for (Y0.95Eu0.052O3 red-emitting phosphors, and the processing window was defined. Particle size and shape are significantly affected by the ion concentration and the urea/RE3+ molar ratio R (RE3+=Y3++Eu3+. A low ion concentration is beneficial in forming monodisperse spheres and extending their formation domain. Increasing R results in a gradual change in the composition of spherical particles from the core-shell Eu(OHCO3@Y(OHCO3 structure to a homogeneous solid solution, thereby significantly lowering the calcination temperature at which precursors convert to oxides. Upon UV excitation into the charge-transfer band at 254 nm, the uniform phosphor spheres of (Y0.95Eu0.052O3 exhibit typical red emissions at 613 nm; the emission is stronger from larger particles mainly because of their smaller surface area. Both the luminescence intensity and quantum efficiency of the oxide phosphors increase with elevated calcination temperatures. The spherical shape and excellent dispersion of the precursor particles (~450 nm in diameter have been well retained after calcination at 1000 circleC for 4 h, and the resultant oxide phosphors exhibit external and internal quantum efficiencies of 50 and 82%, respectively.

Damage characterization for particles filled semi-crystalline polymer

Directory of Open Access Journals (Sweden)

Lauro Franck

2015-01-01

Full Text Available Damage evolution and characterization in semi-crystalline polymer filled with particles under various loadings is still a challenge. A specific damage characterization method using Digital Image Correlation is proposed for a wide range of strain rates considering tensile tests with hydraulic jacks as well as Hopkinson's bars. This damage measurement is obtained by using and adapting the SEE method [1] which was developed to characterize the behaviour laws at constant strain rates of polymeric materials in dynamic. To validate the characterization process, various damage measurement techniques are used under quasi-static conditions before to apply the procedure in dynamic. So, the well-known damage characterization by loss of stiffness technique under quasi-static loading is applied to a polypropylene. In addition, an in-situ tensile test, carried out in a microtomograph, is used to observe the cavitation phenomenon in real time. A good correlation is obtained between all these techniques and consequently the proposed technique is supposed suitable for measuring the ductile damage observed in semi-crystalline polymers under dynamic loading. By applying it to the semi-crystalline polymer at moderate and high speed loadings, the damage evolution is measured and it is observed that the damage evolution is not strain rate dependent but the failure strain on the contrary is strain rate dependent.

A new method for preparing mono-dispersed nanoparticles using magnetized water

Science.gov (United States)

Nakhaei Pour, Ali; Gholizadeh, Mostafa; Housaindokht, Mohammadreza; Moosavi, Fatemeh; Monhemi, Hasan

2017-04-01

We studied the use of magnetized water on the size of the nanoparticles. Magnetized water found to reduce the diameter of the nanoparticles during a homogeneous precipitation process, which is a combination of nucleation and nuclei growth processes. We found that the modified water, which demonstrated different physical properties especially on the surface tension and viscosity, significantly influenced the both processes. Therefore, the nucleation process was initially prolonged in the homogeneous precipitation process due to the lower critical size of nucleus and higher rate of nucleation, and consequently formed smaller particles and a larger number of particles. Furthermore, the growth rate of nanoparticles was hindered owing to the higher viscosity of the water and restriction in the mass transport process. As a result, the precipitated particles with the magnetized water were eventually structured smaller particle diameter compared to the bulk. The presented method in here indicated a low cost, straightforward, and feasible technique for industrial application. In addition, this method could open a new promising perspective on nanomaterial synthesis in order to facilitate the production of monodispersed nanoparticles. Molecular dynamic confirmed that surface tension decreased as the external magnetic field was applied. Moreover, the density profile illustrated that the average number of hydrogen atoms is greater than oxygen atoms.

Quantitative structure-activity relationships for green algae growth inhibition by polymer particles.

NARCIS (Netherlands)

Nolte, Tom M; Peijnenburg, Willie J G M; Hendriks, A Jan; van de Meent, Dik

After use and disposal of chemical products, many types of polymer particles end up in the aquatic environment with potential toxic effects to primary producers like green algae. In this study, we have developed Quantitative Structure-Activity Relationships (QSARs) for a set of highly structural

Molecular and structural properties of polymer composites filled with activated charcoal particles

Energy Technology Data Exchange (ETDEWEB)

Tahir, Dahlang, E-mail: dtahir@fmipa.unhas.ac.id; Bakri, Fahrul [Department of Physics, Hasanuddin University, Makassar 90245 Indonesia (Indonesia); Liong, Syarifuddin [Department of Chemistry, Hasanuddin University, Makassar 90245 Indonesia (Indonesia)

2016-03-11

We have studied the molecular properties, structural properties, and chemical composition of composites by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy, and X-ray fluorescence (XRF) spectroscopy, respectively. FTIR spectra shows absorption band of hydroxyl group (-OH), methyl group (-CH{sub 3}) and aromatic group (C-C). The absorption band for aromatic group (C-C) shows the formation of carbonaceous in composites. XRF shows chemical composition of composites, which the main chemicals are SO{sub 3}, Cl, and ZnO. The loss on ignition value (LOI) of activated charcoal indicates high carbonaceous matter. The crystallite size for diffraction pattern from hydrogel polymer is about 17 nm and for activated charcoal are about 19 nm. The crystallite size of the polymer is lower than that of activated charcoal, which make possible of the particle from filler in contact with each other to form continuous conducting polymer through polymer matrix.

Structure and Dynamics of Polymer/Polymer grafted nanoparticle composite

Science.gov (United States)

Archer, Lynden

Addition of nanoparticles to polymers is a well-practiced methodology for augmenting various properties of the polymer host, including mechanical strength, thermal stability, barrier properties, dimensional stability and wear resistance. Many of these property changes are known to arise from nanoparticle-induced modification of polymer structure and chain dynamics, which are strong functions of the dispersion state of the nanoparticles' and on their relative size (D) to polymer chain dimensions (e.g. Random coil radius Rg or entanglement mesh size a) . This talk will discuss polymer nanocomposites (PNCs) comprised of Polyethylene Glycol (PEG) tethered silica nanoparticles (SiO2-PEG) dispersed in polymers as model systems for investigating phase stability and dynamics of PNCs. On the basis of small-angle X-ray Scattering, it will be shown that favorable enthalpic interactions between particle-tethered chains and a polymer host provides an important mechanism for creating PNCs in which particle aggregation is avoided. The talk will report on polymer and particle scale dynamics in these materials and will show that grafted nanoparticles well dispersed in a polymer host strongly influence the host polymer relaxation dynamics on all timescales and the polymers in turn produce dramatic changes in the nature (from diffusive to hyperdiffusive) and speed of nano particle decorrelation dynamics at the polymer entanglement threshold. A local viscosity model capable of explaining these observations is discussed and the results compared with scaling theories for NP motions in polymers This material is based on work supported by the National Science Foundation Award Nos. DMR-1609125 and CBET-1512297.

Generation of colloidal granules and capsules from double emulsion drops

Science.gov (United States)

Hess, Kathryn S.

Assemblies of colloidal particles are extensively used in ceramic processing, pharmaceuticals, inks and coatings. In this project, the aim was to develop a new technique to fabricate monodispersed colloidal assemblies. The use of microfluidic devices and emulsion processing allows for the fabrication of complex materials that can be used in a variety of applications. A microfluidic device is used to create monodispersed water/oil/water (w/o/w) double emulsions with interior droplets of colloidal silica suspension ranging in size from tens to hundreds of microns. By tailoring the osmotic pressure using glycerol as a solute in the continuous and inner phases of the emulsion, we can control the final volume size of the monodispersed silica colloidal crystals that form in the inner droplets of the double emulsion. Modifying the ionic strength in the colloidal dispersion can be used to affect the particle-particle interactions and crystal formation of the final colloidal particle. This w/o/w technique has been used with other systems of metal oxide colloids and cellulose nanocrystals. Encapsulation of the colloidal suspension in a polymer shell for the generation of ceramic-polymer core-shell particles has also been developed. These core-shell particles have spawned new research in the field of locally resonant acoustic metamaterials. Systems and chemistries for creating cellulose hydrogels within the double emulsions have also been researched. Water in oil single emulsions and double emulsions have been used to create cellulose hydrogel spheres in the sub-100 micron diameter range. Oil/water/oil double emulsions allow us to create stable cellulose capsules. The addition of a second hydrogel polymer, such as acrylate or alginate, further strengthens the cellulose gel network and can also be processed into capsules and particles using the microfluidic device. This work could have promising applications in acoustic metamaterials, personal care products, pharmaceuticals

Preparation of UO_2 Fine Particle by Hydrolysis of Uranium(IV) Alkoxide

OpenAIRE

Satoh, Isamu; Takahashi, Mitsuyuki; Miura, Shigeyuki

1997-01-01

Fine particles of uranium(IV) dioxides were obtained by hydrolysis of uranium(IV) ethoxide which was synthesized by reacting uranium tetrachloride with sodium ethoxide. The monodispersed submicrometer particles were confirmed by SEM observation.

Understanding Effect of Constraint Release Environment on End-to-End Vector Relaxation of Linear Polymer Chains

KAUST Repository

Shivokhin, Maksim E.; Read, Daniel J.; Kouloumasis, Dimitris; Kocen, Rok; Zhuge, Flanco; Bailly, Christian; Hadjichristidis, Nikolaos; Likhtman, Alexei E.

2017-01-01

of a linear probe chain. For this purpose we first validate the ability of the model to consistently predict both the viscoelastic and dielectric response of monodisperse and binary mixtures of type A polymers, based on published experimental data. We

Development of polymer-biomolecule core-shell particles for biomedical applications

Science.gov (United States)

Suthiwangcharoen, Nisaraporn

Developing efficient strategies to introduce biomolecules around polymeric nanoparticles (NPs) is critical for targeted delivery of therapeutic or diagnostic agents. Although polymeric NPs have been well established, problems such as toxicity, stability, and immunoresistance remain potential concerns. The first part of this dissertation focuses on the development of nanosized targeted drug delivery vehicle in cancer chemotherapy. The vehicle was created by the self-assembly of folate-grafted filamentous bacteriophage M13 with poly(caprolactone- b-2-vinylpyridine) while doxorubicin, the antitumor drugs, was successfully loaded in the interior of the vehicles. These particles offer unique properties of being able to selectively target tumor cells while appearing to be safe and non-toxic to normal cells. Although they have shown great prospects in many biomedical applications, less is known about the interactions between biomolecules and polymers. The next part of the dissertation focuses on the self-assembly of proteins and polymers to create polymer-protein core-shell nanoparticles (PPCS-NPs). Several proteins with different isoelectric points and molecular weights were employed to demonstrate a versatility of our assembly method while a series of esterified derivatives of poly(2-hydroxyethyl methacrylate) (pHEMA) were synthesized to evaluate the interaction between proteins and polymers. Our data indicated that the polymers containing pyridine residues can successfully assemble with proteins, and the mechanism is mainly governed by hydrogen bonding and the hydrophobic/hydrophilic interactions. This in turn helps retaining proteins' folding conformation and functionality, which are also demonstrated in the in vitro/in vivo cellular uptake of the PPCS-NPs in endothelial cells. The last part of the dissertation focuses on the self-assembly of the bienzyme-polymer NPs. Glucose oxidase (GOX) together with horseradish peroxidase (HRP) were employed to construct bienzyme

A co-flow-focusing monodisperse microbubble generator

KAUST Repository

Zhang, Jiaming; Li, Erqiang; Thoroddsen, Sigurdur T

2014-01-01

We use a simple and inexpensive microfluidic device, which is based on microscope glass slides and two tapered glass capillaries, to produce monodisperse microbubbles. The innermost capillary used for transporting the gas is inserted into the second capillary, with its 2 μm sharp tip aligned with the center of the converging-diverging throat of the second capillary. This configuration provides a small and smooth gas flow rate, and a high velocity gradient at the tube outlet. Highly monodisperse microbubbles with diameters ranging from 3.5 to 60 microns have been successfully produced at a rate of up to 40 kHz. A simple scaling law, which is based on the capillary number and liquid-to-gas flow rate ratio, successfully predicts the bubble size. © 2014 IOP Publishing Ltd.

A co-flow-focusing monodisperse microbubble generator

KAUST Repository

Zhang, Jiaming

2014-02-14

We use a simple and inexpensive microfluidic device, which is based on microscope glass slides and two tapered glass capillaries, to produce monodisperse microbubbles. The innermost capillary used for transporting the gas is inserted into the second capillary, with its 2 μm sharp tip aligned with the center of the converging-diverging throat of the second capillary. This configuration provides a small and smooth gas flow rate, and a high velocity gradient at the tube outlet. Highly monodisperse microbubbles with diameters ranging from 3.5 to 60 microns have been successfully produced at a rate of up to 40 kHz. A simple scaling law, which is based on the capillary number and liquid-to-gas flow rate ratio, successfully predicts the bubble size. © 2014 IOP Publishing Ltd.

Preparation of polymer-blended quinine nanocomposite particles by spray drying and assessment of their instrumental bitterness-masking effect using a taste sensor.

Science.gov (United States)

Taki, Moeko; Tagami, Tatsuaki; Ozeki, Tetsuya

2017-05-01

The development of taste-masking technologies for foods and drugs is essential because it would enable people to consume and receive healthy and therapeutic effect without distress. In the current study, in order to develop a novel method to prepare nanocomposite particles (microparticles containing bitter nanoparticles) in only one step, by using spray drying, a two-solution mixing nozzle-equipped spray dryer that we previously reported was used. The nanocomposite particles with or without poorly water-soluble polymers prepared using our spray-drying technique were characterized. (1) The organic solution containing quinine, a model of bitter compound and poorly water-soluble polymers and (2) sugar alcohol (mannitol) aqueous solution were separately flown in tubes and two solutions were spray dried through two-solution type spray nozzle to prepare polymer-blended quinine nanocomposite particles. Mean diameters of nanoparticles, taste-masking effect and dissolution rate of quinine were evaluated. The results of taste masking by taste sensor suggested that the polymer (Eudragit EPO, Eudragit S100 or Ethyl cellulose)-blended quinine nanocomposite particles exhibited marked masking of instrumental quinine bitterness compared with the quinine nanocomposite particles alone. Quinine nanocomposite formulations altered the quinine dissolution rate, indicating that they can control intestinal absorption of quinine. These results suggest that polymer-blended quinine composite particles prepared using our spray-drying technique are useful for masking bitter tastes in the field of food and pharmaceutical industry.

Investigation of Monodisperse Dendrimeric Polysaccharide Nanoparticle Dispersions Using Small Angle Neutron Scattering

Science.gov (United States)

Atkinson, John; Nickels, Jonathan; Papp-Szabo, Erzsi; Katsaras, John; Dutcher, John

2015-03-01

Phytoglycogen is a highly branched polysaccharide that is very similar to the energy storage molecule glycogen. We have isolated monodisperse phytoglycogen nanoparticles from corn and these particles are attractive for applications in the cosmetic, food and beverage, and biomedical industries. Many of these promising applications are due to the special interaction between the nanoparticles and water, which results in: (1) high solubility; (2) low viscosity and high stability in aqueous dispersions; and (3) a remarkable capacity to sequester and retain water. Our rheology measurements indicate that the nanoparticles behave like hard spheres in water, with the viscosity diverging for concentrations >25% (w/w). Because of this, aqueous suspensions of phytoglycogen provide an ideal platform for detailed testing of theories of colloidal glasses and jamming. To further explore the interaction of the phytoglycogen particles and water, we have performed small angle neutron scattering (SANS) measurements on the Extended Q-Range SANS (EQ-SANS) diffractometer at the Spallation Neutron Source at Oak Ridge National Laboratory. Measurements performed on phytoglycogen dispersions in mixtures of hydrogenated and deuterated water have allowed us to determine the particle size and average particle spacing as a function of the phytoglycogen concentration in the limits of dilute and concentrated dispersions.

Formation of microscopic particles during the degradation of different polymers.

Science.gov (United States)

Lambert, Scott; Wagner, Martin

2016-10-01

This study investigated the formation and size distribution of microscopic plastic particles during the degradation of different plastic materials. Particle number concentrations in the size range 30 nm-60 μm were measured by nanoparticle tracking analysis (NTA) and Coulter Counter techniques. Each of the plastics used exhibited a measureable increase in the release of particles into the surrounding solution, with polystyrene (PS) and polylactic acid (PLA) generating the highest particle concentrations. After 112 d, particle concentrations ranged from 2147 particles ml(-1) in the control (C) to 92,465 particles ml(-1) for PS in the 2-60 μm size class; 1.2 × 10(5) particles ml(-1) (C) to 11.6 × 10(6) for PLA in the 0.6-18 μm size class; and 0.2 × 10(8) particles ml(-1) (C) to 6.4 × 10(8) particles ml(-1) for PS in the 30-2000 nm size class (84 d). A classification of samples based on principal component analysis showed a separation between the different plastic types, with PLA clustering individually in each of the three size classes. In addition, particle size distribution models were used to examine more closely the size distribution data generated by NTA. Overall, the results indicate that at the beginning of plastic weathering processes chain scission at the polymer surface causes many very small particles to be released into the surrounding solution and those concentrations may vary between plastic types. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis of Monodisperse Iron Oxide Nanoparticles without Surfactants

Directory of Open Access Journals (Sweden)

Xiao-Chen Yang

2014-01-01

Full Text Available Monodisperse iron oxide nanoparticles could be successfully synthesized with two kinds of precipitants through a precipitation method. As-prepared nanoparticles in the size around 10 nm with regular spherical-like shape were achieved by adjusting pH values. NaOH and NH3·H2O were used as two precipitants for comparison. The average size of nanoparticles with NH3·H2O precipitant got smaller and represented better dispersibility, while nanoparticles with NaOH precipitant represented better magnetic property. This work provided a simple method without using any organic solvents, organic metal salts, or surfactants which could easily obtain monodisperse nanoparticles with tunable morphology.

Transparent Conductive Adhesives for Tandem Solar Cells Using Polymer-Particle Composites

Energy Technology Data Exchange (ETDEWEB)

Klein, Talysa [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Lee, Benjamin G [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Schnabel, Manuel [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Warren, Emily L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Stradins, Paul [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Tamboli, Adele C [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Van Hest, Marinus F [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2018-02-14

Transparent conductive adhesives (TCAs) can enable conductivity between two substrates, which is useful for a wide range of electronic devices. Here, we have developed a TCA composed of a polymer-particle blend with ethylene-vinyl acetate as the transparent adhesive and metal-coated flexible poly(methyl methacrylate) microspheres as the conductive particles that can provide conductivity and adhesion regardless of the surface texture. This TCA layer was designed to be nearly transparent, conductive in only the out-of-plane direction, and of practical adhesive strength to hold the substrates together. The series resistance was measured at 0.3 and 0.8 O cm2 for 8 and 0.2% particle coverage, respectively, while remaining over 92% was transparent in both cases. For applications in photovoltaic devices, such as mechanically stacked multijunction III-V/Si cells, a TCA with 1% particle coverage will have less than 0.5% power loss due to the resistance and less than 1% shading loss to the bottom cell.

Coagulation of Agglomerates Consisting of Polydisperse Primary Particles.

Science.gov (United States)

Goudeli, E; Eggersdorfer, M L; Pratsinis, S E

2016-09-13

The ballistic agglomeration of polydisperse particles is investigated by an event-driven (ED) method and compared to the coagulation of spherical particles and agglomerates consisting of monodisperse primary particles (PPs). It is shown for the first time to our knowledge that increasing the width or polydispersity of the PP size distribution initially accelerates the coagulation rate of their agglomerates but delays the attainment of their asymptotic fractal-like structure and self-preserving size distribution (SPSD) without altering them, provided that sufficiently large numbers of PPs are employed. For example, the standard asymptotic mass fractal dimension, Df, of 1.91 is attained when clusters are formed containing, on average, about 15 monodisperse PPs, consistent with fractal theory and the literature. In contrast, when polydisperse PPs with a geometric standard deviation of 3 are employed, about 500 PPs are needed to attain that Df. Even though the same asymptotic Df and mass-mobility exponent, Dfm, are attained regardless of PP polydispersity, the asymptotic prefactors or lacunarities of Df and Dfm increase with PP polydispersity. For monodisperse PPs, the average agglomerate radius of gyration, rg, becomes larger than the mobility radius, rm, when agglomerates consist of more than 15 PPs. Increasing PP polydispersity increases that number of PPs similarly to the above for the attainment of the asymptotic Df or Dfm. The agglomeration kinetics are quantified by the overall collision frequency function. When the SPSD is attained, the collision frequency is independent of PP polydispersity. Accounting for the SPSD polydispersity in the overall agglomerate collision frequency is in good agreement with that frequency from detailed ED simulations once the SPSD is reached. Most importantly, the coagulation of agglomerates is described well by a monodisperse model for agglomerate and PP sizes, whereas the detailed agglomerate size distribution can be obtained by

Monodisperse Platinum and Rhodium Nanoparticles as Model Heterogeneous Catalysts

Energy Technology Data Exchange (ETDEWEB)

Grass, Michael Edward [Univ. of California, Berkeley, CA (United States)

2008-09-01

Model heterogeneous catalysts have been synthesized and studied to better understand how the surface structure of noble metal nanoparticles affects catalytic performance. In this project, monodisperse rhodium and platinum nanoparticles of controlled size and shape have been synthesized by solution phase polyol reduction, stabilized by polyvinylpyrrolidone (PVP). Model catalysts have been developed using these nanoparticles by two methods: synthesis of mesoporous silica (SBA-15) in the presence of nanoparticles (nanoparticle encapsulation, NE) to form a composite of metal nanoparticles supported on SBA-15 and by deposition of the particles onto a silicon wafer using Langmuir-Blodgett (LB) monolayer deposition. The particle shapes were analyzed by transmission electron microscopy (TEM) and high resolution TEM (HRTEM) and the sizes were determined by TEM, X-ray diffraction (XRD), and in the case of NE samples, room temperature H₂ and CO adsorption isotherms. Catalytic studies were carried out in homebuilt gas-phase reactors. For the nanoparticles supported on SBA-15, the catalysts are in powder form and were studied using the homebuilt systems as plug-flow reactors. In the case of nanoparticles deposited on silicon wafers, the same systems were operated as batch reactors. This dissertation has focused on the synthesis, characterization, and reaction studies of model noble metal heterogeneous catalysts. Careful control of particle size and shape has been accomplished though solution phase synthesis of Pt and Rh nanoparticles in order to elucidate further structure-reactivity relationships in noble metal catalysis.

Electrochemical etching amplification of low-let recoil particle tracks in polymers for fast neutron dosimetry

International Nuclear Information System (INIS)

Sohrabi, M.; Morgan, K.Z.

1975-11-01

An electrochemical etching method for the amplification of fast-neutron-induced recoil particle tracks in polymers was investigated. The technique gave superior results over those obtained by conventional etching methods especially when polycarbonate foils were used for recoil particle track amplification. Electrochemical etching systems capable of multi-foil processing were designed and constructed to demonstrate the feasibility of the techniques for large-scale neutron dosimetry. Electrochemical etching parameters were studied including the nature or type of the polymer foil used, foil thickness and its effect on etching time, the applied voltage and its frequency, the chemical composition, concentration, and temperature of the etchant, distance and angle between the electrodes, and the type of particles such as recoil particles including protons. Recoil particle track density, mean track diameter, and optical density as functions of the mentioned parameters were determined. Each parameter was found to have a distinct effect on the etching results in terms of the measured responses. Several new characteristics of this fast neutron dosimetry method were studied especially for personnel dosimetry using various radiation sources such as nuclear reactors, medical cyclotrons, and isotopic neutron sources. The dose range, neutron energy dependence, directional response, fading characteristics, neutron threshold energy, etc. were investigated

One-pot template-free synthesis of monodisperse hollow hydrogel microspheres and their resulting properties.

Science.gov (United States)

Lim, Hyung-Seok; Kwon, Eunji; Lee, Moonjoo; Moo Lee, Young; Suh, Kyung-Do

2013-08-01

Monodisperse poly(methacrylic acid/ethyleneglycoldimethacrylate) (MAA/EGDMA) hollow microcapsules, which exhibit pH-responsive behavior, are prepared by diffusion of cationic surfactants and hydrophobic interaction. During the association of the negatively charged hydrogel microspheres and an oppositely charged surfactant (cetyltrimethylammonium bromide, CTA(+)B), the hydrophobic polymer-surfactant complexes that form are separated from the internal water; consequently, a hollow structure can be formed. Confocal laser scanning microscopy, UV spectro-scopy and zeta potential are employed to study the formation of the hollow structure during the diffusion of the cationic surfactant. The controlled release behavior of methylene blue as a model drug from the as-prepared poly(MAA/EGDMA) microcapsules with a hollow structure is investigated under different pH conditions. The hollow structure can be retained, even during repetitive pH changes. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A simple two-step method to fabricate highly transparent ITO/polymer nanocomposite films

International Nuclear Information System (INIS)

Liu, Haitao; Zeng, Xiaofei; Kong, Xiangrong; Bian, Shuguang; Chen, Jianfeng

2012-01-01

Highlights: ► A simple two-step method without further surface modification step was employed. ► ITO nanoparticles were easily to be uniformly dispersed in polymer matrix. ► ITO/polymer nanocomposite film had high transparency and UV/IR blocking properties. - Abstract: Transparent functional indium tin oxide (ITO)/polymer nanocomposite films were fabricated via a simple approach with two steps. Firstly, the functional monodisperse ITO nanoparticles were synthesized via a facile nonaqueous solvothermal method using bifunctional chemical agent (N-methyl-pyrrolidone, NMP) as the reaction solvent and surface modifier. Secondly, the ITO/acrylics polyurethane (PUA) nanocomposite films were fabricated by a simple sol-solution mixing method without any further surface modification step as often employed traditionally. Flower-like ITO nanoclusters with about 45 nm in diameter were mono-dispersed in ethyl acetate and each nanocluster was assembled by nearly spherical nanoparticles with primary size of 7–9 nm in diameter. The ITO nanoclusters exhibited an excellent dispersibility in polymer matrix of PUA, remaining their original size without any further agglomeration. When the loading content of ITO nanoclusters reached to 5 wt%, the transparent functional nanocomposite film featured a high transparency more than 85% in the visible light region (at 550 nm), meanwhile cutting off near-infrared radiation about 50% at 1500 nm and blocking UV ray about 45% at 350 nm. It could be potential for transparent functional coating materials applications.

Particle size dependence of the Young's modulus of filled polymers: 1. Preliminary experiments

NARCIS (Netherlands)

Vollenberg, P.H.T.; Heikens, D.

1989-01-01

Experimental results are reported from which it appears that in the case of polymer filled with silane-treated glass beads the Young's modulus is, in accordance with present theory, independent of the particle size of the filler. However, if pure glass beads are used as filler, the Young's modulus

Coated particles for lithium battery cathodes

Science.gov (United States)

Singh, Mohit; Eitouni, Hany Basam; Pratt, Russell Clayton; Mullin, Scott Allen; Wang, Xiao-Liang

2017-07-18

Particles of cathodic materials are coated with polymer to prevent direct contact between the particles and the surrounding electrolyte. The polymers are held in place either by a) growing the polymers from initiators covalently bound to the particle, b) attachment of the already-formed polymers by covalently linking to functional groups attached to the particle, or c) electrostatic interactions resulting from incorporation of cationic or anionic groups in the polymer chain. Carbon or ceramic coatings may first be formed on the surfaces of the particles before the particles are coated with polymer. The polymer coating is both electronically and ionically conductive.

Encapsulation of anticancer drug and magnetic particles in biodegradable polymer nanospheres

Energy Technology Data Exchange (ETDEWEB)

Koneracka, M; Zavisova, V; Tomasovicova, N; Kopcansky, P; Timko, M; JurIkova, A; Csach, K; Kavecansky, V; Lancz, G [Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, Kosice (Slovakia); Muckova, M [Hameln rds a.s., Horna 36, Modra (Slovakia)], E-mail: konerack@saske.sk

2008-05-21

In this study, we have prepared PLGA (poly-D,L-lactide-co-glycolide) nanospheres loaded with biocompatible magnetic fluid and anticancer drug taxol by a modified nanoprecipitation technique and investigated their magnetic properties. A magnetic fluid, MF-PEG, with a biocompatible layer of polyethylene glycol (PEG), was chosen as a magnetic carrier. The PLGA, whose copolymer ratio of D,L-lactide to glycolide is 85:15, was utilized as a capsulation material. Taxol, as an important anticancer drug, was chosen for its significant role against a wide range of tumours. The morphology and particle size distributions of the prepared nanospheres were investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) and showed a spherical shape of prepared nanospheres with size 250 nm. Infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetry (TGA) analysis confirmed incorporation of magnetic particles and taxol into the PLGA polymer. The results showed good encapsulation with magnetite content 21.5 wt% and taxol 0.5 wt%. Magnetic properties of magnetic fluids and taxol within the PLGA polymer matrix were investigated by SQUID magnetometry from 4.2 to 300 K. The SQUID measurements showed superparamagnetism of prepared nanospheres with a blocking temperature of 160 K and saturation magnetization 1.4 mT.

Polystyrene Core-Silica Shell Particles with Defined Nanoarchitectures as a Versatile Platform for Suspension Array Technology.

Science.gov (United States)

Sarma, Dominik; Gawlitza, Kornelia; Rurack, Knut

2016-04-19

The need for rapid and high-throughput screening in analytical laboratories has led to significant growth in interest in suspension array technologies (SATs), especially with regard to cytometric assays targeting a low to medium number of analytes. Such SAT or bead-based assays rely on spherical objects that constitute the analytical platform. Usually, functionalized polymer or silica (SiO2) microbeads are used which each have distinct advantages and drawbacks. In this paper, we present a straightforward synthetic route to highly monodisperse SiO2-coated polystyrene core-shell (CS) beads for SAT with controllable architectures from smooth to raspberry- and multilayer-like shells by varying the molecular weight of poly(vinylpyrrolidone) (PVP), which was used as the stabilizer of the cores. The combination of both organic polymer core and a structurally controlled inorganic SiO2 shell in one hybrid particle holds great promises for flexible next-generation design of the spherical platform. The particles were characterized by electron microscopy (SEM, T-SEM, and TEM), thermogravimetry, flow cytometry, and nitrogen adsorption/desorption, offering comprehensive information on the composition, size, structure, and surface area. All particles show ideal cytometric detection patterns and facile handling due to the hybrid structure. The beads are endowed with straightforward modification possibilities through the defined SiO2 shells. We successfully implemented the particles in fluorometric SAT model assays, illustrating the benefits of tailored surface area which is readily available for small-molecule anchoring. Very promising assay performance was shown for DNA hybridization assays with quantification limits down to 8 fmol.

Universal shape characteristics for the mesoscopic star-shaped polymer via dissipative particle dynamics simulations

Science.gov (United States)

Kalyuzhnyi, O.; Ilnytskyi, J. M.; Holovatch, Yu; von Ferber, C.

2018-05-01

In this paper we study the shape characteristics of star-like polymers in various solvent quality using a mesoscopic level of modeling. The dissipative particle dynamics simulations are performed for the homogeneous and four different heterogeneous star polymers with the same molecular weight. We analyse the gyration radius and asphericity at the poor, good and θ-solvent regimes. Detailed explanation based on interplay between enthalpic and entropic contributions to the free energy and analyses on of the asphericity of individual branches are provided to explain the increase of the apsphericity in θ-solvent regime.

High-speed monodisperse droplet generation by ultrasonically controlled micro-jet breakup

Science.gov (United States)

Frommhold, Philipp Erhard; Lippert, Alexander; Holsteyns, Frank Ludwig; Mettin, Robert

2014-04-01

A liquid jet that is ejected from a nozzle into air will disintegrate into drops via the well-known Plateau-Rayleigh instability within a certain range of Ohnesorge and Reynolds numbers. With the focus on the micrometer scale, we investigate the control of this process by superimposing a suitable ultrasonic signal, which causes the jet to break up into a very precise train of monodisperse droplets. The jet leaves a pressurized container of liquid via a small orifice of about 20 μm diameter. The break-up process and the emerging droplets are recorded via high-speed imaging. An extended parameter study of exit speed and ultrasonic frequency is carried out for deionized water to evaluate the jet's state and the subsequent generation of monodisperse droplets. Maximum exit velocities obtained reach almost 120 m s-1, and frequencies have been applied up to 1.8 MHz. Functionality of the method is confirmed for five additional liquids for moderate jet velocities 38 m s-1. For the uncontrolled jet disintegration, the drop size spectra revealed broad distributions and downstream drop growth by collision, while the acoustic control generated monodisperse droplets with a standard deviation less than 0.5 %. By adjustment of the acoustic excitation frequency, drop diameters could be tuned continuously from about 30 to 50 μm for all exit speeds. Good agreement to former experiments and theoretical approaches is found for the relation of overpressure and jet exit speed, and for the observed stability regions of monodisperse droplet generation in the parameter plane of jet speed and acoustic excitation frequency. Fitting of two free parameters of the general theory to the liquids and nozzles used is found to yield an even higher precision. Furthermore, the high-velocity instability limit of regular jet breakup described by von Ohnesorge has been superseded by more than a factor of two without entering the wind-induced instability regime, and monodisperse droplet generation was

Nano indentation of particulate and polymer films

International Nuclear Information System (INIS)

Akram, Aisha

2001-01-01

A detailed knowledge of the formation and rupture mechanisms of agglomerates is essential when seeking to model equipment designed to produce and process such agglomerated particulate solids. In the work to be described the nano-indentation of two-dimensional agglomerate films was carried out in order to establish a means of identifying the generic breakage mechanisms of agglomerated systems. Data analysis techniques are developed that enable the individual inter-particle junction strengths to be calculated for a model system consisting of rather mono-dispersed colloidal silica particles (20-24 nm diameter) bound with a poly(methyl methacrylate). Applied load and penetration depth data in the range (10 mN and 500 nm respectively) are provided as a function of loading time during a continuous loading. It is argued that these data enable the sequence of the discrete binder bridge failures to be observed thus giving a quantitative indication of the breakage mechanism of this agglomerate system as well as reflect the agglomerate structure. The secondary objective of this work was to produce a range of agglomerates with different mechanical properties, without changing the type and amount of binder or prime particles used in the system. This was achieved by altering the mechanical properties of the binder, poly(methyl methacrylate), by the use of a variety of solvents. From data obtained using nano-indentation on thin films of the treated polymer, brittle and ductile forms of poly(methyl methacrylate) could be distinguished. These trends are reflected, to some degree, in the mechanical response of the agglomerated layers. (author)

Synthesis and characterization of new functionalized polymer-Fe3O4 nanocomposite particles

Directory of Open Access Journals (Sweden)

A. Bukowska

2017-01-01

Full Text Available In this study, Fe3O4 nanoparticles (NPs were functionalized with copolymer or terpolymer bearing glycidyl methacrylate (GMA moieties making them suitable for potential applications as drug delivery systems (DDS. For this purpose, the surface of magnetic nanoparticles was first coated with 3-(trimethoxysilyl propyl methacrylate (MPS by a silanization reaction to introduce reactive methacrylate groups onto the surface. Subsequently, monomers were grafted onto the surface of modified-MPS particles via two polymerization methods: seed emulsion (GMA, divinylbenzene, DVB, and styrene, S and distillation – precipitation (GMA and DVB. The obtained nanocomposite particles were characterized by FTIR (Fourier transform infrared spectroscopy, DR UV-Vis (diffuse reflectance ultraviolet – visible spectroscopy, TEM (transmission electron microscopy combined with EDS (energy dispersive X-ray spectroscopy analysis and DLS (dynamic light scattering. FTIR spectroscopy showed that indeed a polymer – Fe3O4@MPS composite was obtained. TEM and EDS analysis showed that the seed emulsion method resulted in nanosized, 100 nm Fe3O4@MPS core/polymer shell NPs, forming long chains. On the contrary, the distillation – precipitation method caused the formation of an inverted structure, i.e. polymer core coated by a Fe3O4@MPS shell, which exhibited a very coarse size distribution varying from several hundreds to over 2 µm.

Biocombatibility and in vivo toxicity assessment of multilayered polymer encapsulated lanthanide doped particles

International Nuclear Information System (INIS)

Dhanya, C.R.; Sri Sivakumar; Jaishree, J.; Abraham, Annie

2013-01-01

Layer-by-layer (LbL) deposition technique has led to the development of multilayered multifunctional nanoparticles that can prove to be promising system for directed drug delivery. Recently, surface functionalized Lanthanide doped nanoparticles have been explored as a candidate for biomedical applications like bio-detection, fluorescence imaging and drug delivery. The toxicity behaviors of biomedical devices proposed for therapeutic use in human must be checked for their toxicity behaviors in animal models. Here, we have presented an initial systematic animal toxicity study of polymer encapsulated lanthanide doped particle in Swiss Albino mice. Polymer coated LNPs with concentration of 100 nM in PBS was administered intravenously through tail vein according to body weight (4μl/g). Animal behavior, survival and animal mass, were monitored and evaluated over short-term (one week) and long-term (one month) periods, after which animals were euthanized. Blood was collected for evaluating clinical biochemistry (SGOT and SGPT) and hematological parameters, and tissues (liver and kidney) for organ histology. Results demonstrated normal serum clinical biochemistry in animals for both short and long time exposure. Histological examination of LNP treated mice also showed normal histology of liver and kidney even after one month of administration. Similar results were obtained for hematological evaluation. Results exhibited the systemic nontoxic nature of the polymer encapsulated lanthanide particles and their suitability as a tool for tumor targeted drug delivery. (author)

Rotation of magnetic particles inside the polymer matrix of magnetoactive elastomers with a hard magnetic filler

Energy Technology Data Exchange (ETDEWEB)

Stepanov, G.V., E-mail: gstepanov@mail.ru [State Scientific Research Institute of Chemistry and Technology of Organoelement Compounds, 105118 Moscow (Russian Federation); Borin, D.Yu. [TU Dresden, Magnetofluiddynamics, Measuring and Automation Technology, Dresden 01062 (Germany); Storozhenko, P.A. [State Scientific Research Institute of Chemistry and Technology of Organoelement Compounds, 105118 Moscow (Russian Federation)

2017-06-01

We propose the results of research on the magnetic properties of magnetoactive elastomers containing particles of a hard magnetic filler. According to our understanding, the mechanism of re-magnetizing of the composite is based on two competing processes, being the re-magnetizing of the magnetic filler and mechanical rotation of particles inside of the polymer matrix.

Redox active polymers and colloidal particles for flow batteries

Science.gov (United States)

Gavvalapalli, Nagarjuna; Moore, Jeffrey S.; Rodriguez-Lopez, Joaquin; Cheng, Kevin; Shen, Mei; Lichtenstein, Timothy

2018-05-29

The invention provides a redox flow battery comprising a microporous or nanoporous size-exclusion membrane, wherein one cell of the battery contains a redox-active polymer dissolved in the non-aqueous solvent or a redox-active colloidal particle dispersed in the non-aqueous solvent. The redox flow battery provides enhanced ionic conductivity across the electrolyte separator and reduced redox-active species crossover, thereby improving the performance and enabling widespread utilization. Redox active poly(vinylbenzyl ethylviologen) (RAPs) and redox active colloidal particles (RACs) were prepared and were found to be highly effective redox species. Controlled potential bulk electrolysis indicates that 94-99% of the nominal charge on different RAPs is accessible and the electrolysis products are stable upon cycling. The high concentration attainable (>2.0 M) for RAPs in common non-aqueous battery solvents, their electrochemical and chemical reversibility, and their hindered transport across porous separators make them attractive materials for non-aqueous redox flow batteries based on size-selectivity.

Controlling Particle Morphologies at Fluid Interfaces: Macro- and Micro- approaches

Science.gov (United States)

Beesabathuni, Shilpa Naidu

The controlled generation of varying shaped particles is important for many applications: consumer goods, biomedical diagnostics, food processing, adsorbents and pharmaceuticals which can benefit from the availability of geometrically complex and chemically inhomogeneous particles. This thesis presents two approaches to spherical and non-spherical particle synthesis using macro and microfluidics. In the first approach, a droplet microfluidic technique is explored to fabricate spherical conducting polymer, polyaniline, particles with precise control over morphology and functionality. Microfluidics has recently emerged as an important alternate to the synthesis of complex particles. The conducting polymer, polyaniline, is widely used and known for its stability, high conductivity, and favorable redox properties. In this approach, monodisperse micron-sized polyaniline spherical particles were synthesized using two-phase droplet microfluidics from Aniline and Ammonium persulfate oxidative polymerization in an oil-based continuous phase. The morphology of the polymerized particles is porous in nature which can be used for encapsulation as well as controlled release applications. Encapsulation of an enzyme, glucose oxidase, was also performed using the technique to synthesize microspheres for glucose sensing. The polymer microspheres were characterized using SEM, UV-Vis and EDX to understand the relationship between their microstructure and stability. In the second approach, molten drop impact in a cooling aqueous medium to generate non-spherical particles was explored. Viscoelastic wax based materials are widely used in many applications and their performance and application depends on the particle morphology and size. The deformation of millimeter size molten wax drops as they impacted an immiscible liquid interface was investigated. Spherical molten wax drops impinged on a cooling water bath, then deformed and as a result of solidification were arrested into various

Magnetic particles

Science.gov (United States)

Chang, Manchium (Inventor); Colvin, Michael S. (Inventor)

1989-01-01

Magnetic polymer particles are formed by swelling porous, polymer particles and impregnating the particles with an aqueous solution of precursor magnetic metal salt such as an equimolar mixture of ferrous chloride and ferric chloride. On addition of a basic reagent such as dilute sodium hydroxide, the metal salts are converted to crystals of magnetite which are uniformly contained througout the pores of the polymer particle. The magnetite content can be increased and neutral buoyancy achieved by repetition of the impregnaton and neutralization steps to adjust the magnetite content to a desired level.

Design, preparation, and application of ordered porous polymer materials

International Nuclear Information System (INIS)

Liu, Qingquan; Tang, Zhe; Ou, Baoli; Liu, Lihua; Zhou, Zhihua; Shen, Shaohua; Duan, Yinxiang

2014-01-01

Ordered porous polymer (OPP) materials have extensively application prospects in the field of separation and purification, biomembrane, solid supports for sensors catalysts, scaffolds for tissue engineering, photonic band gap materials owing to ordered pore arrays, uniform and tunable pore size, high specific surface area, great adsorption capacity, and light weight. The present paper reviewed the preparation techniques of OPP materials like breath figures, hard template, and soft template. Finally, the applications of OPP materials in the field of separation, sensors, and biomedicine are introduced, respectively. - Highlights: • Breath figures involve polymer casting under moist ambience. • Hard template employs monodisperse colloidal spheres as a template. • Soft template utilizes the etched block in copolymers as template

Precision polymers and 3D DNA nanostructures: emergent assemblies from new parameter space.

Science.gov (United States)

Serpell, Christopher J; Edwardson, Thomas G W; Chidchob, Pongphak; Carneiro, Karina M M; Sleiman, Hanadi F

2014-11-05

Polymer self-assembly and DNA nanotechnology have both proved to be powerful nanoscale techniques. To date, most attempts to merge the fields have been limited to placing linear DNA segments within a polydisperse block copolymer. Here we show that, by using hydrophobic polymers of a precisely predetermined length conjugated to DNA strands, and addressable 3D DNA prisms, we are able to effect the formation of unprecedented monodisperse quantized superstructures. The structure and properties of larger micelles-of-prisms were probed in depth, revealing their ability to participate in controlled release of their constituent nanostructures, and template light-harvesting energy transfer cascades, mediated through both the addressability of DNA and the controlled aggregation of the polymers.

Formation of monodisperse mesoporous silica microparticles via spray-drying.

Science.gov (United States)

Waldron, Kathryn; Wu, Winston Duo; Wu, Zhangxiong; Liu, Wenjie; Selomulya, Cordelia; Zhao, Dongyuan; Chen, Xiao Dong

2014-03-15

In this work, a protocol to synthesize monodisperse mesoporous silica microparticles via a unique microfluidic jet spray-drying route is reported for the first time. The microparticles demonstrated highly ordered hexagonal mesostructures with surface areas ranging from ~900 up to 1500 m(2)/g and pore volumes from ~0.6 to 0.8 cm(3)/g. The particle size could be easily controlled from ~50 to 100 μm from the same diameter nozzle via changing the initial solute content, or changing the drying temperature. The ratio of the surfactant (CTAB) and silica (TEOS), and the amount of water in the precursor were found to affect the degree of ordering of mesopores by promoting either the self-assembly of the surfactant-silica micelles or the condensation of the silica as two competing processes in evaporation induced self-assembly. The drying rate and the curvature of particles also affected the self-assembly of the mesostructure. The particle mesostructure is not influenced by the inlet drying temperature in the range of 92-160 °C, with even a relatively low temperature of 92 °C producing highly ordered mesoporous microparticles. The spray-drying derived mesoporous silica microparticles, while of larger sizes and more rapidly synthesized, showed a comparable performance with the conventional mesoporous silica MCM-41 in controlled release of a dye, Rhodamine B, indicating that these spray dried microparticles could be used for the immobilisation and controlled release of small molecules. Copyright © 2013 Elsevier Inc. All rights reserved.

Extracellular biosynthesis of monodispersed gold nanoparticles by a SAM capping route

International Nuclear Information System (INIS)

Wen Li; Lin Zhonghua; Gu Pingying; Zhou Jianzhang; Yao Bingxing; Chen Guoliang; Fu Jinkun

2009-01-01

Monodispersed gold nanoparticles capped with a self-assembled monolayer of dodecanethiol were biosynthesized extracellularly by an efficient, simple, and environmental friendly procedure, which involved the use of Bacillus megatherium D01 as the reducing agent and the use of dodecanethiol as the capping ligand at 26 o C. The kinetics of gold nanoparticle formation was followed by transmission electron microscope (TEM) and UV-vis spectroscopy. It was shown that reaction time was an important parameter in controlling the morphology of gold nanoparticles. The effect of thiol on the shape, size, and dispersity of gold nanoparticles was also studied. The results showed that the presence of thiol during the biosynthesis could induce the formation of small size gold nanoparticles (<2.5 nm), hold the shape of spherical nanoparticles, and promote the monodispersity of nanoparticles. Through the modulation of reaction time and the use of thiol, monodispersed spherical gold nanoparticles capped with thiol of 1.9 ± 0.8 nm size were formed by using Bacillus megatherium D01.

Extracellular biosynthesis of monodispersed gold nanoparticles by a SAM capping route

Energy Technology Data Exchange (ETDEWEB)

Wen Li [Xiamen University, Department of Chemistry, College of Chemistry and Chemical Engineering (China); Lin Zhonghua [Xiamen University, State Key Laboratory of Physical Chemistry of Solid Surfaces (China); Gu Pingying [Xiamen University, Department of Chemistry, College of Chemistry and Chemical Engineering (China); Zhou Jianzhang [Xiamen University, State Key Laboratory of Physical Chemistry of Solid Surfaces (China); Yao Bingxing [Xiamen University, School of Life Sciences (China); Chen Guoliang; Fu Jinkun, E-mail: wenli_1976@163.co [Xiamen University, Department of Chemistry, College of Chemistry and Chemical Engineering (China)

2009-02-15

Monodispersed gold nanoparticles capped with a self-assembled monolayer of dodecanethiol were biosynthesized extracellularly by an efficient, simple, and environmental friendly procedure, which involved the use of Bacillus megatherium D01 as the reducing agent and the use of dodecanethiol as the capping ligand at 26 {sup o}C. The kinetics of gold nanoparticle formation was followed by transmission electron microscope (TEM) and UV-vis spectroscopy. It was shown that reaction time was an important parameter in controlling the morphology of gold nanoparticles. The effect of thiol on the shape, size, and dispersity of gold nanoparticles was also studied. The results showed that the presence of thiol during the biosynthesis could induce the formation of small size gold nanoparticles (<2.5 nm), hold the shape of spherical nanoparticles, and promote the monodispersity of nanoparticles. Through the modulation of reaction time and the use of thiol, monodispersed spherical gold nanoparticles capped with thiol of 1.9 {+-} 0.8 nm size were formed by using Bacillus megatherium D01.

Osmotic pressure and virial coefficients of star and comb polymer solutions: dissipative particle dynamics.

Science.gov (United States)

Wang, Tzu-Yu; Fang, Che-Ming; Sheng, Yu-Jane; Tsao, Heng-Kwong

2009-03-28

The effects of macromolecular architecture on the osmotic pressure pi and virial coefficients (B(2) and B(3)) of star and comb polymers in good solvents are studied by dissipative particle dynamics simulations for both dilute and semiconcentrated regimes. The dependence of the osmotic pressure on polymer concentration is directly calculated by considering two reservoirs separated by a semipermeable, fictitious membrane. Our simulation results show that the ratios A(n+1) identical with B(n+1)/R(g)(3n) are essentially constant and A(2) and A(3) are arm number (f) dependent, where R(g) is zero-density radius of gyration. The value of dimensionless virial ratio g = A(3)/A(2)(2) increases with arm number of stars whereas it is essentially arm number independent for comb polymers. In semiconcentrated regime the scaling relation between osmotic pressure and volume fraction, pi proportional to phi(lambda), still holds for both star and comb polymers. For comb polymers, the exponent lambda is close to lambda(*) (approximately = 2.73 for linear chains) and is independent of the arm number. However, for star polymers, the exponent lambda deviates from lambda(*) and actually grows with increasing the arm number. This may be attributed to the significant ternary interactions near the star core in the many-arm systems.

In vivo integrity of polymer-coated gold nanoparticles

Science.gov (United States)

Kreyling, Wolfgang G.; Abdelmonem, Abuelmagd M.; Ali, Zulqurnain; Alves, Frauke; Geiser, Marianne; Haberl, Nadine; Hartmann, Raimo; Hirn, Stephanie; de Aberasturi, Dorleta Jimenez; Kantner, Karsten; Khadem-Saba, Gülnaz; Montenegro, Jose-Maria; Rejman, Joanna; Rojo, Teofilo; de Larramendi, Idoia Ruiz; Ufartes, Roser; Wenk, Alexander; Parak, Wolfgang J.

2015-07-01

Inorganic nanoparticles are frequently engineered with an organic surface coating to improve their physicochemical properties, and it is well known that their colloidal properties may change upon internalization by cells. While the stability of such nanoparticles is typically assayed in simple in vitro tests, their stability in a mammalian organism remains unknown. Here, we show that firmly grafted polymer shells around gold nanoparticles may degrade when injected into rats. We synthesized monodisperse radioactively labelled gold nanoparticles (198Au) and engineered an 111In-labelled polymer shell around them. Upon intravenous injection into rats, quantitative biodistribution analyses performed independently for 198Au and 111In showed partial removal of the polymer shell in vivo. While 198Au accumulates mostly in the liver, part of the 111In shows a non-particulate biodistribution similar to intravenous injection of chelated 111In. Further in vitro studies suggest that degradation of the polymer shell is caused by proteolytic enzymes in the liver. Our results show that even nanoparticles with high colloidal stability can change their physicochemical properties in vivo.

Fabrication of a multifunctional nano-in-micro drug delivery platform by microfluidic templated encapsulation of porous silicon in polymer matrix.

Science.gov (United States)

Zhang, Hongbo; Liu, Dongfei; Shahbazi, Mohammad-Ali; Mäkilä, Ermei; Herranz-Blanco, Bárbara; Salonen, Jarno; Hirvonen, Jouni; Santos, Hélder A

2014-07-09

A multifunctional nano-in-micro drug delivery platform is developed by conjugating the porous silicon nanoparticles with mucoadhesive polymers and subsequent encapsulation into a pH-responsive polymer using microfluidics. The multistage platform shows monodisperse size distribution and pH-responsive payload release, and the released nanoparticles are mucoadhesive. Moreover, this platform is capable of simultaneously loading and releasing multidrugs with distinct properties. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Syringe-vacuum microfluidics: A portable technique to create monodisperse emulsions.

Science.gov (United States)

Abate, Adam R; Weitz, David A

2011-03-16

We present a simple method for creating monodisperse emulsions with microfluidic devices. Unlike conventional approaches that require bulky pumps, control computers, and expertise with device physics to operate devices, our method requires only the microfluidic device and a hand-operated syringe. The fluids needed for the emulsion are loaded into the device inlets, while the syringe is used to create a vacuum at the device outlet; this sucks the fluids through the channels, generating the drops. By controlling the hydrodynamic resistances of the channels using hydrodynamic resistors and valves, we are able to control the properties of the drops. This provides a simple and highly portable method for creating monodisperse emulsions.

Bio-mineralisation on the composites of silicon-based polymer and nanodiamond particles by a species of Serratia Bacteria

International Nuclear Information System (INIS)

Sammon, R.; Mitev, D.; Pramatarova, L.; Hikov, T.; Radeva, E.; Presker, R.

2014-01-01

Serratia sp. NCIMB 40259 is a non-pathogenic Gram-negative bacterium that is able to produce hydroxyapatite by a mechanism involving enzymic cleavage of organic phosphates. Serratia bacteria can attach and form a biofilm on glass, plastics, ceramics and metals and the method can be used to form three dimensional porous scaffolds and for coating 3D structures with hydroxyapatite. The production of calcium phosphate is driven by an acid phosphatase enzyme located in the bacterial cell wall, on fimbriae and within the bacterial extracellular polymeric matrix. Calcium phosphate ceramic may be obtained by two methods: In the first, crystals of calcium phosphate are formed extracellularly within the pre-formed bacterial biofilm grown on the substrata. In the second method, planktonic bacteria catalyse the formation of CaP in suspension and on solid substrata placed in the same container. Composite thin layer of silicon-based polymer and detonated nanodiamond (DND) particles was used as substrate for the process of biomineralization by a species of Serratia. The plasma polymerization (PP) method was chosen to obtain composites of silicon-based polymer, in which DND particles were incorporated. Over the past decades carbon-based nanostructures have been the focus of intense research due to their unique chemical and physical properties. Recently it was shown that the incorporation of the DND particles in a polymer matrix (an organosilicon polymer) changes their physico-chemical properties. The composite films are homogeneous, chemically resistant, thermally and mechanically stable, thus allowing a large amount of biological components to be loaded onto their surface and to be used in tissue engineering, regenerative medicine, implants, stents, biosensors and other medical and biological devices. The aim of this study was to investigate the process of biomineralisation by Serratia bacteria on various composites of silicon-based polymer and detonated nanodiamond particles

Effect of particle size of mineral fillers on polymer-matrix composite shielding materials against ionizing electromagnetic radiation

International Nuclear Information System (INIS)

Belgin, E.E.; Aycik, G.A.

2017-01-01

Filler particle size is an important particle that effects radiation attenuation performance of a composite shielding material but the effects of it have not been exploited so far. In this study, two mineral (hematite-ilmenite) with different particle sizes were used as fillers in a polymer-matrix composite and effects of particle size on shielding performance was investigated within a widerange of radiation energy (0-2000 keV). The thermal and structural properties of the composites were also examined. The results showed that as the filler particle size decreased the shielding performance increased. The highest shielding performance reached was 23% with particle sizes being between <7 and <74 µm. (author)

Linear theory on temporal instability of megahertz faraday waves for monodisperse microdroplet ejection.

Science.gov (United States)

Tsai, Shirley C; Tsai, Chen S

2013-08-01

A linear theory on temporal instability of megahertz Faraday waves for monodisperse microdroplet ejection based on mass conservation and linearized Navier-Stokes equations is presented using the most recently observed micrometer- sized droplet ejection from a millimeter-sized spherical water ball as a specific example. The theory is verified in the experiments utilizing silicon-based multiple-Fourier horn ultrasonic nozzles at megahertz frequency to facilitate temporal instability of the Faraday waves. Specifically, the linear theory not only correctly predicted the Faraday wave frequency and onset threshold of Faraday instability, the effect of viscosity, the dynamics of droplet ejection, but also established the first theoretical formula for the size of the ejected droplets, namely, the droplet diameter equals four-tenths of the Faraday wavelength involved. The high rate of increase in Faraday wave amplitude at megahertz drive frequency subsequent to onset threshold, together with enhanced excitation displacement on the nozzle end face, facilitated by the megahertz multiple Fourier horns in resonance, led to high-rate ejection of micrometer- sized monodisperse droplets (>10(7) droplets/s) at low electrical drive power (<;1 W) with short initiation time (<;0.05 s). This is in stark contrast to the Rayleigh-Plateau instability of a liquid jet, which ejects one droplet at a time. The measured diameters of the droplets ranging from 2.2 to 4.6 μm at 2 to 1 MHz drive frequency fall within the optimum particle size range for pulmonary drug delivery.

Steady shear rheology of dilute polystyrene particle gels

NARCIS (Netherlands)

Folkersma, R.; Diemen, van A.J.G.; Laven, J.; Stein, H.N.

1999-01-01

This paper describes an experimental study on dispersions of monodisperse polystyrene (PS) spheres with a typical radius of 1 µm, dispersed in an electrolyte at high ionic strength, screening the electrostatic repulsion. These suspensions gelate at rest even at low volume fractions of PS particles.

Number concentrations of solid particles from the spinning top aerosol generator

International Nuclear Information System (INIS)

Mitchell, J.P.

1983-02-01

A spinning top aerosol generator has been used to generate monodisperse methylene blue particles in the size range from 0.6 to 6 μm. The number concentrations of these aerosols have been determined by means of an optical particle counter and compared with the equivalent measurements obtained by filter collection and microscopy. (author)

From particle segregation to the granular clock

International Nuclear Information System (INIS)

Lambiotte, R.; Salazar, J.M.; Brenig, L.

2005-01-01

Recently several authors studied the segregation of particles for a system composed of mono-dispersed inelastic spheres contained in a box divided by a wall in the middle. The system exhibited a symmetry breaking leading to an overpopulation of particles in one side of the box. Here we study the segregation of a mixture of particles composed of inelastic hard spheres and fluidized by a vibrating wall. Our numerical simulations show a rich phenomenology: horizontal segregation and periodic behavior. We also propose an empirical system of ODEs representing the proportion of each type of particles and the segregation flux of particles. These equations reproduce the major features observed by the simulations

From particle segregation to the granular clock

Energy Technology Data Exchange (ETDEWEB)

Lambiotte, R. [Physique Statistique, Plasmas et Optique Non-lineaire, Universite Libre de Bruxelles, Campus Plaine, Boulevard du Triomphe, Code Postal 231, 1050 Brussels (Belgium)]. E-mail: rlambiot@ulb.ac.be; Salazar, J.M. [Universite De Bougogne-LRRS UMR-5613 CNRS, Faculte des Sciences Mirande, 9 Av. Alain Savary, 21078 Dijon Cedex (France)]. E-mail: jmarcos@u-bourgogne.fr; Brenig, L. [Physique Statistique, Plasmas et Optique Non-lineaire, Universite Libre de Bruxelles, Campus Plaine, Boulevard du Triomphe, Code Postal 231, 1050 Brussels (Belgium)]. E-mail: lbrenig@ulb.ac.be

2005-08-01

Recently several authors studied the segregation of particles for a system composed of mono-dispersed inelastic spheres contained in a box divided by a wall in the middle. The system exhibited a symmetry breaking leading to an overpopulation of particles in one side of the box. Here we study the segregation of a mixture of particles composed of inelastic hard spheres and fluidized by a vibrating wall. Our numerical simulations show a rich phenomenology: horizontal segregation and periodic behavior. We also propose an empirical system of ODEs representing the proportion of each type of particles and the segregation flux of particles. These equations reproduce the major features observed by the simulations.

Growth of monodisperse nanocrystals of cerium oxide during synthesis and annealing

International Nuclear Information System (INIS)

Ghosh, Swapankumar; Divya, Damodaran; Remani, Kottayilpadi C.; Sreeremya, Thadathil S.

2010-01-01

Monodisperse cerium oxide nanocrystals have been successfully synthesised using simple ammonia precipitation technique from cerium(III) nitrate solution at different temperatures in the range 35-80 o C. The activation energy for growth of CeO 2 nanocrystals during the precipitation is calculated as 11.54 kJ/mol using Arrhenius plot. Average crystal diameter was obtained from XRD analysis, HR-TEM and light scattering (PCS). The analysis of size data from HR-TEM images and PCS clearly indicated the formation of highly crystalline CeO 2 particles in narrow size range. CeO 2 nanocrystals precipitated at 35 o C were further annealed at temperatures in the range 300-700 o C. The activation energy for crystal growth during annealing is also calculated and is close to the reported values. An effort is made to predict the mechanism of crystal growth during the precipitation and annealing.

Core–shell composite particles composed of biodegradable polymer particles and magnetic iron oxide nanoparticles for targeted drug delivery

Energy Technology Data Exchange (ETDEWEB)

Oka, Chiemi; Ushimaru, Kazunori [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan); Horiishi, Nanao [Bengala Techno Laboratory, 9-5-1006, 1-1 Kodai, Miyamae-ku, Kawasaki 216-0007 (Japan); Tsuge, Takeharu [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan); Kitamoto, Yoshitaka, E-mail: kitamoto.y.aa@m.titech.ac.jp [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan)

2015-05-01

Core–shell composite particles with biodegradability and superparamagnetic behavior were prepared using a Pickering emulsion for targeted drug delivery based on magnetic guidance. The composite particles were composed of a core of biodegradable polymer and a shell of assembled magnetic iron oxide nanoparticles. It was found that the dispersibility of the nanoparticles is crucial for controlling the core–shell structure. The addition of a small amount of dispersant into the nanoparticle's suspension could improve the dispersibility and led to the formation of composite particles with a thin magnetic shell covering a polymeric core. The composite particles were also fabricated with a model drug loaded into the core, which was released via hydrolysis of the core under strong alkaline conditions. Because the core can also be biodegraded by lipase, this result suggests that the slow release of the drug from the composite particles should occur inside the body. - Highlights: • Core−shell composites with biodegradability and magnetism are prepared. • O/W emulsion stabilized by iron oxide nanoparticles is utilized for the preparation. • The nanoparticle's dispersibility is crucial for controlling the composite structure. • Composites loading a model drug are also prepared. • The model drug is released with decomposition of the composites.

Elongational viscosity of monodisperse and bidisperse polystyrene melts

DEFF Research Database (Denmark)

Nielsen, Jens Kromann; Rasmussen, Henrik Koblitz; Hassager, Ole

2005-01-01

The startup and steady uniaxial elongational viscosity have been measured for two monodisperse polystyrene melts with molecular weights of 52 kg/mole (PS52K) and 103 kg/mole (PS103K), and for three bidisperse polystyrene melts. The bidisperse melts consist of PS103K or PS52K and a monodisperse...... (closed loop proportional regulator) using the laser in such a way that the stretch rate at the neck is kept constant. The rheometer has been described in more detail in (A. Bach, H.K. Rasmussen and O. Hassager, Journal of Rheology, 47 (2003) 429). PS390K show a decrease in the steady viscosity as a power......-law function of the elongational rate (A. Bach, K. Almdal, H.K. Rasmussen and O. Hassager, Macromolecules 36 (2003) 5174). PS52K and PS103K show that the steady viscosity has a maximum that is respectively 100% and 50% above 3 times the zero-shear-rate viscosity. The bidisperse melts show a significant...

Dry powder inhaler formulation of lipid-polymer hybrid nanoparticles via electrostatically-driven nanoparticle assembly onto microscale carrier particles.

Science.gov (United States)

Yang, Yue; Cheow, Wean Sin; Hadinoto, Kunn

2012-09-15

Lipid-polymer hybrid nanoparticles have emerged as promising nanoscale carriers of therapeutics as they combine the attractive characteristics of liposomes and polymers. Herein we develop dry powder inhaler (DPI) formulation of hybrid nanoparticles composed of poly(lactic-co-glycolic acid) and soybean lecithin as the polymer and lipid constituents, respectively. The hybrid nanoparticles are transformed into inhalable microscale nanocomposite structures by a novel technique based on electrostatically-driven adsorption of nanoparticles onto polysaccharide carrier particles, which eliminates the drawbacks of conventional techniques based on controlled drying (e.g. nanoparticle-specific formulation, low yield). First, we engineer polysaccharide carrier particles made up of chitosan cross-linked with tripolyphosphate and dextran sulphate to exhibit the desired aerosolization characteristics and physical robustness. Second, we investigate the effects of nanoparticle to carrier mass ratio and salt inclusion on the adsorption efficiency, in terms of the nanoparticle loading and yield, from which the optimal formulation is determined. Desorption of the nanoparticles from the carrier particles in phosphate buffer saline is also examined. Lastly, we characterize aerosolization efficiency of the nanocomposite product in vitro, where the emitted dose and respirable fraction are found to be comparable to the values of conventional DPI formulations. Copyright © 2012 Elsevier B.V. All rights reserved.

Synthesis of monodispersed silver nanoparticles using Hibiscus cannabinus leaf extract and its antimicrobial activity

Science.gov (United States)

Bindhu, M. R.; Umadevi, M.

2013-01-01

Synthesis of silver nanoparticles using leaf extract of Hibiscus cannabinus has been investigated. The influences of different concentration of H. cannabinus leaf extract, different metal ion concentration and different reaction time on the above cases on the synthesis of nanoparticles were evaluated. The synthesized nanoparticles were characterized using UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The prepared silver nanoparticles were monodispersed, spherical in shape with the average particle size of 9 nm and shows surface plasmon peak at 446 nm. The study also reveals that the ascorbic acid present in H. cannabinus leaf extract has been used as reducing agent. The prepared silver nanoparticle shows good antimicrobial activity against Escherichia coli, Proteus mirabilis and Shigella flexneri.

Protein-based polymers that bond to DNA : design of virus-like particles and supramolecular nanostructures

NARCIS (Netherlands)

Hernandez Garcia, A.

2014-01-01

In this thesis it is demonstrated that it is possible to use Protein-based Polymers (PbPs) as synthetic binders of DNA (or any other negatively charged polyelectrolyte). The PbPs co-assemble with their DNA templates to form highly organized virus-like particles and supramolecular structures. A

Nanocomposite coatings of Ti/C:H plasma polymer particles providing a surface with variable nanoroughness

Czech Academy of Sciences Publication Activity Database

Solař, P.; Kylián, O.; Polonskyi, O.; Artemenko, A.; Arzhakov, D.; Drábik, M.; Slavínská, D.; Vandrovcová, Marta; Bačáková, Lucie; Biederman, H.

2012-01-01

Roč. 206, č. 21 (2012), s. 4335-4342 ISSN 0257-8972 R&D Projects: GA AV ČR(CZ) KAN101120701 Institutional research plan: CEZ:AV0Z50110509 Keywords : plasma polymer particles * composite film * cell adhesion Subject RIV: EI - Biotechnology ; Bionics Impact factor: 1.941, year: 2012

Synthesis of Barium Titanate (BT) Nano Particles via Hydrothermal Route for the Production of BT-Polymer Nanocomposite

Science.gov (United States)

Habib, A.; Haubner, R.; Jakopic, G.; Stelzer, N.

2007-08-01

Barium titanate (high-k dielectric material) nano-powders (approx. 30 nm to 60 nm) were synthesised using hydrothermal route under moderate conditions. Effect of temperature and time was studied using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction techniques. Obtained barium titanate nano-powders were dispersed in thermoplastic polymethyl methacrylate (PMMA) to get homogeneous dispersions. Thin layers were obtained using these dispersions to achieve BaTiO3 endorsed polymer layers by dip-coating for improved polymer insulators on various substrates e.g., glass, and Au sputtered silicon wafers. SEM and focused ion beam (FIB) techniques were used to study the dispersion of barium titanate nano-particles in PMMA. The layers obtained showed homogenous distribution of BaTiO3 nano particles with no agglomeration.

Unipolar and bipolar diffusion charging of ultrafine particles

International Nuclear Information System (INIS)

Adachi, Motoaki; Okuyama, Kikuo; Kousaka, Yasuo.

1985-01-01

Unipolar and bipolar diffusion charging of monodisperse ultrafine particles of 4 - 100 nm in diameter has been studied experimentally and theoretically. The particles were charged by unipolar and bipolar ions generated by α-ray irradiation and the charge distribution of particles was directly observed in the electric field after the growth of them by condensation of di-butyl phthalate vapor. In both cases of unipolar and bipolar charging, the experimental results have been found in good agreement with the solution of basic equations where Fuchs' formula is used as the combination probability of an ion with a particle. (author)

Photonic Molecularly Imprinted Polymer Film for the Detection of Testosterone in Aqueous Samples

Directory of Open Access Journals (Sweden)

Abbas J. Kadhem

2018-03-01

Full Text Available The detection of testosterone in aqueous solutions is a difficult task due to the low concentration levels that are relevant in environmental and physiological samples. Current analytical methods are expensive and/or complex. To address this issue, we fabricated a molecularly imprinted polymer (MIP photonic film for the detection of testosterone in water. The films were obtained using colloidal crystals as templates for the pore morphology. Monodispersed silica particles with an average diameter 330 nm were used to obtain the colloidal crystal by vertical deposition. A solution of acrylic acid with testosterone as the imprinted template was infiltrated in the colloidal crystal and polymerized via bulk polymerization; the particles were then removed by acid etching and the testosterone eluted by a suitable solvent. The material was characterized by FTIR, swelling experiments and microscopy; MIPs were investigated by equilibrium rebinding, kinetics and reuse experiments. The results showed that the MIPs exhibited selectivity to the template, a 30-min equilibration time and stability after at least six cycles of use and regeneration. After incubation, the reflectance spectra of the films showed a shift of the Bragg diffraction peak that correlated with testosterone concentration in the 5–100 ppb range.

Modification of chitosan membranes with nanosilica particles as polymer electrolyte membranes

Energy Technology Data Exchange (ETDEWEB)

Kusumastuti, Ella, E-mail: ella.kusuma@gmail.com; Siniwi, Widasari Trisna, E-mail: wsiniwi@gmail.com; Mahatmanti, F. Widhi; Jumaeri [Department of Chemistry, Faculty of Mathematics and Natural Sciences, State University of Semarang D6 Building 2" n" d floor, Sekaran Unnes Campus, Gunungpati, Semarang (Indonesia); Atmaja, Lukman; Widiastuti, Nurul [Department of Chemistry, Faculty of Mathematics and Natural Sciences, Tenth November Institute of Technology Keputih ITS Campus, Sukolilo, Surabaya (Indonesia)

2016-04-19

Chitosan has been widely used as polymer matrix for Polymer Electrolyte Membrane (PEM) application replacing Nafion which has shortcomings in terms of high methanol permeability that degrades the performance of fuel cells. Chitosan membranes modification is performed by adding nanosilica to prevent methanol transport through the membrane. Nanosilica is synthesized by sol-gel method and the particle diameter is obtained by analysis using Breunner Emmet Teller (BET) that is 6.59 nm. Nanosilica is mixed with chitosan solution to obtain nanosilica-chitosan as polymer electrolyte membrane. The membranes are synthesized through phase inversion method with nanosilica composition including 0; 0.5; 1; 2; 3; 5; and 10% w/w of chitosan. Characterization of the membranes indicate that the results of water swelling, proton conductivity and methanol permeability of the membrane with 3% nanosilica respectively were 49.23%, 0.231 S/cm, and 5.43 x 10{sup −7} cm{sup 2}/s. Based on the results of membrane selectivity calculation, the optimum membrane is the composition of 3% nanosilica with value 5.91 x 105 S s cm{sup −3}. The results of functional groups analysis with FTIR showed that it was only physical interaction that occurred between chitosan and nanosilica since no significant changes found in peak around the wave number 1000-1250 cm{sup −-1}.

Growth of monodisperse nanocrystals of cerium oxide during synthesis and annealing

Energy Technology Data Exchange (ETDEWEB)

Ghosh, Swapankumar, E-mail: swapankumar.ghosh2@mail.dcu.ie; Divya, Damodaran [National Institute for Interdisciplinary Science and Technology (NIIST), Council of Scientific and Industrial Research (CSIR) (India); Remani, Kottayilpadi C. [Sree Neelakanda Government Sanskrit College, Department of Chemistry (India); Sreeremya, Thadathil S. [National Institute for Interdisciplinary Science and Technology (NIIST), Council of Scientific and Industrial Research (CSIR) (India)

2010-06-15

Monodisperse cerium oxide nanocrystals have been successfully synthesised using simple ammonia precipitation technique from cerium(III) nitrate solution at different temperatures in the range 35-80 {sup o}C. The activation energy for growth of CeO{sub 2} nanocrystals during the precipitation is calculated as 11.54 kJ/mol using Arrhenius plot. Average crystal diameter was obtained from XRD analysis, HR-TEM and light scattering (PCS). The analysis of size data from HR-TEM images and PCS clearly indicated the formation of highly crystalline CeO{sub 2} particles in narrow size range. CeO{sub 2} nanocrystals precipitated at 35 {sup o}C were further annealed at temperatures in the range 300-700 {sup o}C. The activation energy for crystal growth during annealing is also calculated and is close to the reported values. An effort is made to predict the mechanism of crystal growth during the precipitation and annealing.

Dependency of Nanodiamond Particle Size and Outermost-Surface Composition on Organo-Modification: Evaluation by Formation of Organized Molecular Films and Nanohybridization with Organic Polymers.

Science.gov (United States)

Tasaki, Taira; Guo, Yifei; Meng, Qi; Mamun, Muhammad Abdullah Al; Kasahara, Yusuke; Akasaka, Shuichi; Fujimori, Atsuhiro

2017-04-26

The formation behavior of organized organo-modified nanodiamond films and polymer nanocomposites has been investigated using nanodiamonds of several different particle sizes and outermost-surface compositions. The nanodiamond particle sizes used in this study were 3 and 5 nm, and the outermost surface contained -OH and/or -COOH groups. The nanodiamond was organo-modified to prepare -OH 2 + cations and -COO - anions on the outermost surface by carboxylic anion of fatty acid and long-chain phosphonium cation, respectively. The surface of nanodiamond is known to be covered with a nanolayer of adsorbed water, which was exploited here for the organo-modification of nanodiamond with long-chain fatty acids via adsorption, leading to nanodispersions of nanodiamond in general organic solvents as a mimic of solvency. Particle multilayers were then formed via the Langmuir-Blodgett technique and subjected to fine structural analysis. The organo-modification enabled integration and multilayer formation of inorganic nanoparticles due to enhancement of the van der Waals interactions between the chains. Therefore, "encounters" between the organo-modifying chain and the inorganic particles led to solubilization of the inorganic particles and enhanced interactions between the particles; this can be regarded as imparting a new functionality to the organic molecules. Nanocomposites with a transparent crystalline polymer were fabricated by nanodispersing the nanodiamond into the polymer matrix, which was achievable due to the organo-modification. The resulting transparent nanocomposites displayed enhanced degrees of crystallization and improved crystallization temperatures, compared with the neat polymer, due to a nucleation effect.

Novel polymer composite having diamond particles and boron nitride platelets for thermal management of electric vehicle motors

Science.gov (United States)

Nakajima, Anri; Shoji, Atsushi; Yonemori, Kei; Seo, Nobuhide

2016-02-01

Thermal conductivities of silicone matrix polymers including fillers of diamond particles and/or hexagonal boron nitride (h-BN) platelets were systematically investigated in an attempt to find a thermal interface material (TIM) having high isotropic thermal conductivity and high electrical insulating ability to enable efficient heat dissipation from the motor coil ends of electric vehicles. The TIM with mixed fillers of diamond particles and h-BN platelets had a maximum thermal conductivity of 6.1 W m-1 K-1 that was almost isotropic. This is the highest value among the thermal conductivities of TIMs with silicone matrix polymer reported to date. The mechanism behind the thermal conductivity of the TIMs was also examined from the viewpoint of the change in the number of thermally conductive networks and/or a decrease in the thermal resistivity of junctions of neighboring diamond particles through the incorporation of h-BN platelets. The TIMs developed in this study will make it possible to manage the heat of electric motors and will help to popularize electric vehicles.

Morphological control of calcium oxalate particles in the presence of poly-(styrene-alt-maleic acid)

International Nuclear Information System (INIS)

Yu Jiaguo; Tang Hua; Cheng Bei; Zhao Xiujian

2004-01-01

Calcium oxalate (CaOx) particles exhibiting different shapes and phase structures were fabricated by a simple precipitation reaction of sodium oxalate with calcium chloride in the absence and presence of poly-(styrene-alt-maleic acid) (PSMA) as a crystal modifier at room temperature. The as-obtained products were characterized with scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effects of reaction conditions including pH, [Ca 2+ ]/[C 2 O 4 2- ] ratio and concentration of PSMA and CaC 2 O 4 on the crystal forms and morphologies of the as-obtained calcium oxalate were investigated. The results show that various crystal morphologies of calcium oxalate, such as parallelograms, plates, spheres, bipyramids etc. can be obtained depending on the experimental conditions. Higher polymer concentration favors formation of the metastable calcium oxalate dihydrate (COD) crystals. Lower pH is beneficial to the formation of plate-like CaOx crystals. Especially, the monodispersed parallelogram-like CaOx crystals can be produced by PSMA as an additive at pH 2. PSMA may act as a good inhibitor for urolithiasis since it induces the formation of COD and reduces the particle size of CaOx. This research may provide new insight into the morphological control of CaOx particles and the prevention of urolithiasis

211At-labelling of polymer particles for radiotherapy: synthesis, purification and stability

International Nuclear Information System (INIS)

Larsen, R.H.; Hassfjell, S.P.; Hoff, P.; Alstad, J.; Bjoergum, J.

1993-01-01

Cyclotron-produced 211 At was distilled from a Bi metal target and coupled to N-succinimidyl-3-(trimethylstannyl)benzoate. The resulting N-succinimidyl-3-( 211 At)astatobenzoate was thereafter coupled to aminated monosized polymer particles with a diameter of 1.8 μm. The total time elapsed from the end of the cyclotron irradiation until the final product was prepared was about 2.5 hours. From 23 to 51% of the target activity at the end of bombardment was measured in the final conjugate. Solid-liquid extraction purification of the astatinated intermediate, using Sep-pak columns (Waters), gave more reproducible yields in the final conjugation step. The 211 At-labelled particles were incubated with fetal calf serum, human serum and human full blood at room temperature. The 211 At activity on the particles was measured before and after three times washing at 4, 24 and 48 hours. The stability was not significantly different from 100% for all media and for all time points. This indicates that 211 At-labelled particles can be stable under in vivo conditions, and may thereby be a promising agent for intracavitary radiotherapy on free-floating cancer cells or surface fixed cells. (Author)

Comb polymer architecture and particle size effects on the behavior of biphasic nanoparticle inks for direct-write assembly

Science.gov (United States)

Yoshikawa, Jun

Biphasic nanoparticle mixtures composed of attractive and repulsive colloidal species enable the direct-write assembly of 3D structures with much finer features than those produced by pure colloidal gels. These mixtures rely on the use of comb polymer dispersants to render one particle population stable, while the other population is attractive. In this thesis, we systematically investigate the effects of comb polymer architecture and particle size ratio on the behavior of biphasic nanoparticle inks with the overarching aim of further advancing the direct-write assembly of 3D colloidal structures. We first investigated the effects of both pure polyelectrolytes, poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA), and comb polymer dispersants composed of a PMAA backbone with methoxy-poly(ethylene oxide) (mPEO) teeth of varying molecular weights on the stability of barium titanate (BaTiO 3) suspensions. While each dispersant imparts stability to BaTiO 3 nanoparticles at low ionic strength (teeth (MWteeth = 2000) provides stability at higher ionic strengths over a broad range of particle sizes and counterion valencies. These results provide guidelines for tailoring the molecular architecture and functionality of comb polymer dispersants for optimal stabilization of the repulsive particle population within the biphasic inks. Next, particle size effects on the rheological properties of biphasic nanoparticle suspensions are studied. Shear elastic modulus, shear yield stress, and compressive yield stress are measured for mixtures of varying total volume fraction, attractive-to-repulsive volume fraction, and particle size ratio between attractive and repulsive species. Our observations indicate that the repulsive particles hinder the formation of the attractive gel network. The time required for shear elastic modulus to approach a steady-state value increases with the fraction of repulsive species. Furthermore, this behavior becomes more significant with increasing

Observation of Dust Particle Gyromotion in a Magnetized Dusty Plasma

Science.gov (United States)

Compton, C. S.; Amatucci, W. E.; Gatling, G.; Tejero, E.

2008-11-01

In dusty plasma research, gyromotion of the dust has been difficult to observe experimentally. Previous experiments by Amatucci et al. have shown gyromotion of a single dust particle [1]. This early work was performed with alumina dust that had a size distribution and non-uniformly shaped particles. In the current experiment, evidence of spherical, monodispersed, dust particles exhibiting gyromotion has been observed. Silica particles 0.97 micrometers in diameter are suspended in a DC glow discharge argon plasma. The experiment is performed in the Naval Research Laboratory's DUsty PLasma EXperiment (DUPLEX Jr.). DUPLEX is a 61-cm tall by 46-cm diameter acrylic chamber allowing full 360 degree optical access for diagnostics. The neutral pressure for the experiment is 230 mTorr with a 275 V bias between the circular electrodes. The electrodes have a separation of 4 cm. A strong magnetic field is created by 2 pairs of neodymium iron boride magnets placed above and below the anode and cathode respectively. The resulting field is 1.4 kG. The dust particles are illuminated with a 25 mW, 672 nm laser. Images are captured using an intensified CCD camera and a consumer digital video cassette recorder. Recent evidence of gyromotion of spherical, monodispersed, dust particles will be presented. [1] Amatucci, W.E., et al., Phys. Plasmas, 11, 2097 (2004)

Mechanical reinforcement and segmental dynamics of polymer nanocomposites

Science.gov (United States)

Gong, Shushan

The addition of nanofiller into a polymer matrix will dramatically change the physical properties of polymer. The introduction of nanofiller makes the polymer more applicable in many industries, such as automobile tires, coatings, semiconductors, and packaging. The altered properties are not the simple combination of the characters from the two components. The interactions in polymer nanocomposites play an important role in determining the physical properties. This dissertation focuses on the mechanical properties of polymer nanocomposites (silica/poly-2-vinylpyridine) above their glass transition temperature Tg, as a model for automobile tires, which utilize small silica particles in crosslinked rubber far above Tg. We also investigate the impacts of the interaction between particle filler and polymer matrix on the altered mechanical properties. Dielectric relaxation spectroscopy (DRS) is used to study the glassy bound polymer layers formed around the particles. The results show evidence of the existence of immobilized polymer layers at the surface of each nanoparticle. At the same time, the thickness of the immobilized polymer layers is quantified and formed to be around 2 nm. Then we consider particles with glassy bound polymer layers are bridged together (either rubbery bridge or glassy bridge) by polymer chains and form small clusters. Clusters finally percolate to form a particle-polymer network as loading fraction increases. Rheology is used to study the network formation, and to predict the boundary of rubbery bridge and glassy bridge regimes. The distance between particles determines the type of polymer bridging. The particle spacing larger than Kuhn length makes flexible (rubbery) bridge with rheology described by a flexible Rouse model for percolation. When the spacing is shorter than the Kuhn length (~ 1nm), stiffer bridge forms instead, which is called glassy bridge. The mechanical differences between rubbery bridge and glassy bridge, and the effect of

Segmented block copolymers with monodisperse aramide end-segments

NARCIS (Netherlands)

Araichimani, A.; Gaymans, R.J.

2008-01-01

Segmented block copolymers were synthesized using monodisperse diaramide (TT) as hard segments and PTMO with a molecular weight of 2 900 g · mol-1 as soft segments. The aramide: PTMO segment ratio was increased from 1:1 to 2:1 thereby changing the structure from a high molecular weight multi-block

Amperometric detection of morphine based on poly(3,4-ethylenedioxythiophene) immobilized molecularly imprinted polymer particles prepared by precipitation polymerization

International Nuclear Information System (INIS)

Ho, K.-C.; Yeh, W.-M.; Tung, T.-S.; Liao, J.-Y.

2005-01-01

Molecular imprinting is a novel technique used for chiral separation, artificial antibodies, sensors, and assays. Typically, molecular imprinted polymers (MIPs) are monoliths with irregular shapes. However, microspherical shapes with more uniform size can be obtained by the method of precipitation polymerization, which offers a higher active surface area by manipulating its compositions. In this study, MIP particles for the target molecule, morphine, were synthesized using a precipitation polymerization method that is more facile than the previous one that produced a thermally polymerized bulk. The conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), was utilized to immobilize the MIP particles onto the indium tin oxide (ITO) glass as a MIP/PEDOT-modified electrode. The sensitivity for the MIP/PEDOT-modified electrode with MIP particles was 41.63 μA/cm 2 mM, which is more sensitive than that with non-MIP particles or that of a single PEDOT film with no incorporated particles in detecting morphine ranging from 0.1 to 2 mM. The detection limit was 0.3 mM (S/N = 3). In addition, we presented that the modified electrode can discriminate codeine that plays an interfering species

Synthesis and characterization of silica–titania core–shell particles

Indian Academy of Sciences (India)

Nearly monodispersed particles of silica were prepared and coated with uniform layers of titanium dioxide in anatase phase by hydrolysis and condensation of titanium butoxide. The coating thickness could be altered by adjusting the concentration of reactants (titanium butoxide and water) and the amount of added silica ...

Synthesis of monodispersed silver nanoparticles using Hibiscus cannabinus leaf extract and its antimicrobial activity.

Science.gov (United States)

Bindhu, M R; Umadevi, M

2013-01-15

Synthesis of silver nanoparticles using leaf extract of Hibiscus cannabinus has been investigated. The influences of different concentration of H. cannabinus leaf extract, different metal ion concentration and different reaction time on the above cases on the synthesis of nanoparticles were evaluated. The synthesized nanoparticles were characterized using UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The prepared silver nanoparticles were monodispersed, spherical in shape with the average particle size of 9 nm and shows surface plasmon peak at 446 nm. The study also reveals that the ascorbic acid present in H. cannabinus leaf extract has been used as reducing agent. The prepared silver nanoparticle shows good antimicrobial activity against Escherichia coli, Proteus mirabilis and Shigella flexneri. Copyright © 2012 Elsevier B.V. All rights reserved.

Investigating the particle to fibre transition threshold during electrohydrodynamic atomization of a polymer solution

Energy Technology Data Exchange (ETDEWEB)

Husain, O.; Lau, W.; Edirisinghe, M.; Parhizkar, M., E-mail: maryam.parhizkar.09@ucl.ac.uk

2016-08-01

Electrohydrodynamic atomization (EHDA) is a key research area for producing micro and nano-sized structures. This process can be categorized into two main operating regimes: electrospraying for particle generation and electrospinning for fibre production. Producing particles/fibres of the desired size or morphology depends on two main factors; properties of the polymeric solution used and the processing conditions including flow rate, applied voltage and collection distance. In this work the particle-fibre transition region was analyzed by changing the polymer concentration of PLGA poly (lactic-co-glycolic acid) in acetone between 2 and 25 wt%. Subsequently the processing conditions were adjusted to study the optimum transition parameters. Additionally the EHDA configuration was also modified by adding a metallic plate to observe the deposition area. The diameter and the distance of the plate from the capillary tip were adjusted to investigate variations in particle and fibre morphologies as well. It was found that complete transition from particles to fibres occurs at 20 wt% indicating concentration to be the dominant criterion. Low flow rates yielded fibres without beads. However the applied voltage and distance between the tip of the nozzle jetting the polymer solution and collector (working distance) did not yield definitive results. Reducing the collector distance and increasing applied voltages produces smooth as well as beaded fibres. Addition of a metal plate reduces particle size by ~ 1 μm; the fibre size increases especially with increasing plate diameter while bead density and size reduces when the disc is fixed closer to the capillary tip. Additionally, the deposition area is reduced by 70% and 57% with the addition of metal plates of 30 mm and 60 mm, respectively. The results indicate that a metal plate can be utilized further to tune the particle/fibre size and morphology and this also significantly increases the yield of EHDA process which is

Particle clustering within a two-phase turbulent pipe jet

Science.gov (United States)

Lau, Timothy; Nathan, Graham

2016-11-01

A comprehensive study of the influence of Stokes number on the instantaneous distributions of particles within a well-characterised, two-phase, turbulent pipe jet in a weak co-flow was performed. The experiments utilised particles with a narrow size distribution, resulting in a truly mono-disperse particle-laden jet. The jet Reynolds number, based on the pipe diameter, was in the range 10000 developed technique. The results show that particle clustering is significantly influenced by the exit Stokes number. Particle clustering was found to be significant for 0 . 3 financial contributions by the Australian Research Council (Grant No. DP120102961) and the Australian Renewable Energy Agency (Grant No. USO034).

Synthesis of monodisperse silver nanoparticles for ink-jet printed flexible electronics

Energy Technology Data Exchange (ETDEWEB)

Zhang Zhiliang; Zhang Xingye; Xin Zhiqing; Deng Mengmeng; Wen Yongqiang; Song Yanlin, E-mail: zhangxy@iccas.ac.cn, E-mail: ylsong@iccas.ac.cn [Beijing National Laboratory for Molecular Sciences (BNLMS), Key Lab of Organic Solids, Laboratory of New Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

2011-10-21

In this study, monodisperse silver nanoparticles were synthesized with a new reduction system consisting of adipoyl hydrazide and dextrose at ambient temperature. By this facile and rapid approach, high concentration monodisperse silver nanoparticles were obtained on a large scale at low protectant/AgNO{sub 3} mass ratio which was highly beneficial to low cost and high conductivity. Based on the synthesized monodisperse silver nanoparticles, conductive inks were prepared with water, ethanol and ethylene glycol as solvents, and were expected to be more environmentally friendly. A series of electrocircuits were fabricated by ink-jet printing silver nanoparticle ink on paper substrate with a commercial printer, and they had low resistivity in the range of 9.18 x 10{sup -8}-8.76 x 10{sup -8} {Omega} m after thermal treatment at 160 {sup 0}C for 30 min, which was about five times that of bulk silver (1.586 x 10{sup -8} {Omega} m). Moreover, a radio frequency identification (RFID) antenna was fabricated by ink-jet printing, and 6 m wireless identification was realized after an Alien higgs-3 chip was mounted on the printed antenna by the flip-chip method. These flexible electrocircuits produced by ink-jet printing would have enormous potential for low cost electrodes and sensor devices.

Synthesis of monodisperse silver nanoparticles for ink-jet printed flexible electronics

International Nuclear Information System (INIS)

Zhang Zhiliang; Zhang Xingye; Xin Zhiqing; Deng Mengmeng; Wen Yongqiang; Song Yanlin

2011-01-01

In this study, monodisperse silver nanoparticles were synthesized with a new reduction system consisting of adipoyl hydrazide and dextrose at ambient temperature. By this facile and rapid approach, high concentration monodisperse silver nanoparticles were obtained on a large scale at low protectant/AgNO 3 mass ratio which was highly beneficial to low cost and high conductivity. Based on the synthesized monodisperse silver nanoparticles, conductive inks were prepared with water, ethanol and ethylene glycol as solvents, and were expected to be more environmentally friendly. A series of electrocircuits were fabricated by ink-jet printing silver nanoparticle ink on paper substrate with a commercial printer, and they had low resistivity in the range of 9.18 x 10 -8 -8.76 x 10 -8 Ω m after thermal treatment at 160 0 C for 30 min, which was about five times that of bulk silver (1.586 x 10 -8 Ω m). Moreover, a radio frequency identification (RFID) antenna was fabricated by ink-jet printing, and 6 m wireless identification was realized after an Alien higgs-3 chip was mounted on the printed antenna by the flip-chip method. These flexible electrocircuits produced by ink-jet printing would have enormous potential for low cost electrodes and sensor devices.

Self-healing properties of TiO{sub 2} particle-polymer composite coatings for protection of aluminum alloys against corrosion in seawater

Energy Technology Data Exchange (ETDEWEB)

Yabuki, A. [Faculty of Engineering, Hiroshima University, Higashi-hiroshima (Japan); Urushihara, W.; Kinugasa, J. [Materials Research Laboratory, KOBE STEEL, LTD., Takatsukadai, Nishi-ku, Kobe, Hyogo (Japan); Sugano, K. [Machinery and Engineering Company, KOBE STEEL, LTD., Shinhama, Arai, Takasago, Hyogo (Japan)

2011-10-15

TiO{sub 2} particle-polymer composite coatings were applied to the surface of a 5083 aluminum alloy. After using a knife to create an artificial defect, polarization resistance was monitored in artificial seawater at a temperature of 30 C. The polarization resistance of the specimen coated with the composite polymer containing 3 vol% TiO{sub 2} particles increased significantly over time, suggesting that the composite coating had self-healing properties. A carbon-containing 2-{mu}m thick film was found on the coated aluminum substrate at the site of the artificial defect. The formation of the film was related to the dissolution of bisphenol A (BPA), which is a chemical precursor of the polymer coating that behaved as an inhibiting agent. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Limiting diffusion current at rotating disk electrode with dense particle layer.

Science.gov (United States)

Weroński, P; Nosek, M; Batys, P

2013-09-28

Exploiting the concept of diffusion permeability of multilayer gel membrane and porous multilayer we have derived a simple analytical equation for the limiting diffusion current at rotating disk electrode (RDE) covered by a thin layer with variable tortuosity and porosity, under the assumption of negligible convection in the porous film. The variation of limiting diffusion current with the porosity and tortuosity of the film can be described in terms of the equivalent thickness of stagnant solution layer, i.e., the average ratio of squared tortuosity to porosity. In case of monolayer of monodisperse spherical particles, the equivalent layer thickness is an algebraic function of the surface coverage. Thus, by means of cyclic voltammetry of RDE with a deposited particle monolayer we can determine the monolayer surface coverage. The effect of particle layer adsorbed on the surface of RDE increases non-linearly with surface coverage. We have tested our theoretical results experimentally by means of cyclic voltammetry measurements of limiting diffusion current at the glassy carbon RDE covered with a monolayer of 3 μm silica particles. The theoretical and experimental results are in a good agreement at the surface coverage higher than 0.7. This result suggests that convection in a monolayer of 3 μm monodisperse spherical particles is negligibly small, in the context of the coverage determination, in the range of very dense particle layers.

Hydrophilic block copolymer-directed growth of lanthanum hydroxide nano-particles

Energy Technology Data Exchange (ETDEWEB)

Bouyer, F.; Sanson, N.; Gerardin, C. [Laboratoire de Materiaux Catalytiques et Catalyse en Chimie Organique, UMR 5618 CNRS-ENSCM-UM1, FR 1878, Institut Gerhardt, 34 - Montpellier (France); Destarac, M. [Centre de Recherches Rhodia Aubervilliers, 93 - Aubervilliers (France)

2006-03-15

Stable hairy lanthanum hydroxide nano-particles were synthesized in water by performing hydrolysis and condensation reactions of lanthanum cations in the presence of double hydrophilic poly-acrylic acid-b-polyacrylamide block copolymers (PAA-b-PAM). In the first step, the addition of asymmetric PAA-b-PAM copolymers (M{sub w,PAA} {<=} M{sub w,PAM}) to lanthanum salt solutions, both at pH = 5.5, induces the formation of monodispersed micellar aggregates, which are predominantly isotropic. The core of the hybrid aggregates is constituted of a lanthanum polyacrylate complex whose formation is due to bidentate coordination bonding between La{sup 3+} and acrylate groups, as shown by ATR-FTIR experiments and pH measurements. The size of the micellar aggregates depends on the molecular weight of the copolymer but is independent of the copolymer to metal ratio in solution. In the second step, the hydrolysis of lanthanum ions is induced by addition of a strong base such as sodium hydroxide. Either flocculated suspensions or stable anisotropic or spherical nano-particles of lanthanum hydrolysis products were obtained depending on the metal complexation ratio [acrylate]/[La]. The variation of that parameter also enables the control of the size of the core-corona nano-particles obtained by lanthanum hydroxylation. The asymmetry degree of the copolymer was shown to influence both the size and the shape of the particles. Elongated particles with a high aspect ratio, up to 10, were obtained with very asymmetric copolymers (M{sub w,PAM}/M{sub w,PAA}{>=}10) while shorter rice grain-like particles were obtained with a less asymmetric copolymer. The asymmetry degree also influences the value of the critical metal complexation degree required to obtain stable colloidal suspensions of polymer-stabilized lanthanum hydroxide. (authors)

Encapsulation of Polymer Colloids in a Sol-Gel Matrix. Direct-Writing of Coassembling Organic-Inorganic Hybrid Photonic Crystals.

Science.gov (United States)

Mikosch, Annabel; Kuehne, Alexander J C

2016-03-22

The spontaneous self-assembly of polymer colloids into ordered arrangements provides a facile strategy for the creation of photonic crystals. However, these structures often suffer from defects and insufficient cohesion, which result in flaking and delamination from the substrate. A coassembly process has been developed for convective assembly, resulting in large-area encapsulated colloidal crystals. However, to generate patterns or discrete deposits in designated places, convective assembly is not suitable. Here we experimentally develop conditions for direct-writing of coassembling monodisperse dye-doped polystyrene particles with a sol-gel precursor to form solid encapsulated photonic crystals. In a simple procedure the colloids are formulated in a sol-gel precursor solution, drop-cast on a flat substrate, and dried. We here establish the optimal parameters to form reproducible highly ordered photonic crystals with good optical performance. The obtained photonic crystals interact with light in the visible spectrum with a narrow optical stop-gap.

Synthesis of Silica Nanoparticles by Sol-Gel: Size-Dependent Properties, Surface Modification, and Applications in Silica-Polymer Nano composites-A Review

International Nuclear Information System (INIS)

Ismail, A.R.; Vejayakumaran, P.

2012-01-01

Application of silica nanoparticles as fillers in the preparation of nano composite of polymers has drawn much attention, due to the increased demand for new materials with improved thermal, mechanical, physical, and chemical properties. Recent developments in the synthesis of monodispersed, narrow-size distribution of nanoparticles by sol-gel method provide significant boost to development of silica-polymer nano composites. This paper is written by emphasizing on the synthesis of silica nanoparticles, characterization on size-dependent properties, and surface modification for the preparation of homogeneous nano composites, generally by sol-gel technique. The effect of nano silica on the properties of various types of silica-polymer composites is also summarized.

Chromo- and fluorophoric water-soluble polymers and silica particles by nucleophilic substitution reaction of poly(vinyl amine

Directory of Open Access Journals (Sweden)

Katja Hofmann

2010-07-01

Full Text Available Novel chromophoric and fluorescent carbonitrile-functionalized poly(vinyl amine (PVAm and PVAm/silica particles were synthesized by means of nucleophilic aromatic substitution of 8-oxo-8H-acenaphtho[1,2-b]pyrrol-9-carbonitrile (1 with PVAm in water. The water solubility of 1 has been mediated by 2,6-O-β-dimethylcyclodextrin or by pre-adsorption onto silica particles. Furthermore, 1 was converted with isopropylamine into the model compound 1-M. All new compounds were characterized by NMR, FTIR, UV–vis and fluorescence spectroscopy. The solvent-dependent UV–vis absorption and fluorescence emission band positions of the model compound and the carbonitrile-functionalized PVAm were studied and interpreted using the empirical Kamlet–Taft solvent parameters π* (dipolarity/polarizability, α (hydrogen-bond donating capacity and β (hydrogen-accepting ability in terms of the linear solvation energy relationship (LSER. The solvent-independent regression coefficients a, b and s were determined using multiple linear correlation analysis. It is shown, that the chains of the polymer have a significant influence on the solvatochromic behavior of 1-P. The structure of the carbonitrile 1-Si bound to polymer-modified silica particles was studied by means of X-ray photoelectron spectroscopy (XPS and Brunauer–Emmett–Teller (BET measurements. Fluorescent silica particles were obtained as shown by fluorescence spectroscopy with a diffuse reflectance technique.

Statistical optimization of microencapsulation process for coating of magnesium particles with Viton polymer

Energy Technology Data Exchange (ETDEWEB)

Pourmortazavi, Seied Mahdi, E-mail: pourmortazavi@yahoo.com [Faculty of Material and Manufacturing Technologies, Malek Ashtar University of Technology, P.O. Box 16765-3454, Tehran (Iran, Islamic Republic of); Babaee, Saeed; Ashtiani, Fatemeh Shamsi [Faculty of Chemistry & Chemical Engineering, Malek Ashtar University of Technology, Tehran (Iran, Islamic Republic of)

2015-09-15

Graphical abstract: - Highlights: • Surface of magnesium particles was modified with Viton via solvent/non-solvent method. • FT-IR, SEM, EDX, Map analysis, and TG/DSC techniques were employed to characterize the coated particles. • Coating process factors were optimized by Taguchi robust design. • The importance of coating conditions on resistance of coated magnesium against oxidation was studied. - Abstract: The surface of magnesium particles was modified by coating with Viton as an energetic polymer using solvent/non-solvent technique. Taguchi robust method was utilized as a statistical experiment design to evaluate the role of coating process parameters. The coated magnesium particles were characterized by various techniques, i.e., Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and thermogravimetry (TG), and differential scanning calorimetry (DSC). The results showed that the coating of magnesium powder with the Viton leads to a higher resistance of metal against oxidation in the presence of air atmosphere. Meanwhile, tuning of the coating process parameters (i.e., percent of Viton, flow rate of non-solvent addition, and type of solvent) influences on the resistance of the metal particles against thermal oxidation. Coating of magnesium particles yields Viton coated particles with higher thermal stability (632 °C); in comparison with the pure magnesium powder, which commences oxidation in the presence of air atmosphere at a lower temperature of 260 °C.

Monodisperse metal nanoparticle catalysts on silica mesoporous supports: synthesis, characterizations, and catalytic reactions

Energy Technology Data Exchange (ETDEWEB)

Somorjai, G.A.

2009-09-14

The design of high performance catalyst achieving near 100% product selectivity at maximum activity is one of the most important goals in the modern catalytic science research. To this end, the preparation of model catalysts whose catalytic performances can be predicted in a systematic and rational manner is of significant importance, which thereby allows understanding of the molecular ingredients affecting the catalytic performances. We have designed novel 3-dimensional (3D) high surface area model catalysts by the integration of colloidal metal nanoparticles and mesoporous silica supports. Monodisperse colloidal metal NPs with controllable size and shape were synthesized using dendrimers, polymers, or surfactants as the surface stabilizers. The size of Pt, and Rh nanoparticles can be varied from sub 1 nm to 15 nm, while the shape of Pt can be controlled to cube, cuboctahedron, and octahedron. The 3D model catalysts were generated by the incorporation of metal nanoparticles into the pores of mesoporous silica supports via two methods: capillary inclusion (CI) and nanoparticle encapsulation (NE). The former method relies on the sonication-induced inclusion of metal nanoparticles into the pores of mesoporous silica, whereas the latter is performed by the encapsulation of metal nanoparticles during the hydrothermal synthesis of mesoporous silica. The 3D model catalysts were comprehensively characterized by a variety of physical and chemical methods. These catalysts were found to show structure sensitivity in hydrocarbon conversion reactions. The Pt NPs supported on mesoporous SBA-15 silica (Pt/SBA-15) displayed significant particle size sensitivity in ethane hydrogenolysis over the size range of 1-7 nm. The Pt/SBA-15 catalysts also exhibited particle size dependent product selectivity in cyclohexene hydrogenation, crotonaldehyde hydrogenation, and pyrrole hydrogenation. The Rh loaded SBA-15 silica catalyst showed structure sensitivity in CO oxidation reaction. In

Consistent model reduction of polymer chains in solution in dissipative particle dynamics: Model description

KAUST Repository

Moreno Chaparro, Nicolas

2015-06-30

We introduce a framework for model reduction of polymer chain models for dissipative particle dynamics (DPD) simulations, where the properties governing the phase equilibria such as the characteristic size of the chain, compressibility, density, and temperature are preserved. The proposed methodology reduces the number of degrees of freedom required in traditional DPD representations to model equilibrium properties of systems with complex molecules (e.g., linear polymers). Based on geometrical considerations we explicitly account for the correlation between beads in fine-grained DPD models and consistently represent the effect of these correlations in a reduced model, in a practical and simple fashion via power laws and the consistent scaling of the simulation parameters. In order to satisfy the geometrical constraints in the reduced model we introduce bond-angle potentials that account for the changes in the chain free energy after the model reduction. Following this coarse-graining process we represent high molecular weight DPD chains (i.e., ≥200≥200 beads per chain) with a significant reduction in the number of particles required (i.e., ≥20≥20 times the original system). We show that our methodology has potential applications modeling systems of high molecular weight molecules at large scales, such as diblock copolymer and DNA.

Ion induced transformation of polymer films into diamond-like carbon incorporating silver nano particles

International Nuclear Information System (INIS)

Schwarz, Florian P.

2010-01-01

Silver containing diamond-like carbon (DLC) is an interesting material for medical engineering from several points of view. On the one hand DLC provides high mechanical robustness. It can be used as biocompatible and wear resistant coating for joint replacing implants. On the other hand silver has antimicrobial properties, which could reduce post-operative inflammations. However conventional production of Ag-DLC by co-deposition of silver and carbon in a plasma process is problematic since it does not allow for a separate control of nano particle morphology and matrix properties. In this work an alternative production method has been developed to circumvent this problem. In metall-DLC-production by ion implantation into a nano composite, silver nano particles are initially formed in solution and then incorporated within a polymer matrix. Finally the polymer is transformed into DLC by ion implantation. The aspects and single steps of this method were investigated with regard to the resulting material's properties. The goal was to design an economically relevant deposition method. Based on experimental results a model of the transformation process has been established, which has also been implemented in a computer simulation. Finally the antibacterial properties of the material have been checked in a biomedical test. Here a bacterial killing rate of 90% could be achieved. (orig.)

Polystyrene Microbeads by Dispersion Polymerization: Effect of Solvent on Particle Morphology

Directory of Open Access Journals (Sweden)

Lei Jinhua

2014-01-01

Full Text Available Polystyrene microspheres (PS were synthesized by dispersion polymerization in ethanol/2-Methoxyethanol (EtOH/EGME blend solvent using styrene (St as monomer, azobisisobutyronitrile (AIBN as initiator, and PVP (polyvinylpyrrolidone K-30 as stabilizer. The typical recipe of dispersion polymerization is as follows: St/Solvent/AIBN/PVP = 10 g/88 g/0.1 g/2 g. The morphology of polystyrene microspheres was characterized by the scanning electron microscopy (SEM and the molecular weights of PS particles were measured by the Ubbelohde viscometer method. The effect of ethanol content in the blend solvent on the morphology and molecular weight of polystyrene was studied. We found that the size of polystyrene microspheres increased and the molecular weight of polystyrene microspheres decreased with the decreasing of the ethanol content in the blend solvent from 100 wt% to 0 wt%. What is more, the size monodispersity of polystyrene microspheres was quite good when the pure ethanol or pure 2-Methoxyethanol was used; however when the blend ethanol/2-Methoxyethanol solvent was used, the polystyrene microspheres became polydisperse. We further found that the monodispersity of polystyrene microspheres can be significantly improved by adding a small amount of water into the blend solvent; the particles became monodisperse when the content of water in the blend solvent was up to 2 wt%.

Gravitational settling of a highly concentrated system of solid spherical particles

Science.gov (United States)

Arkhipov, V. A.; Usanina, A. S.

2017-09-01

In the present paper, we report on the results of an experimental study of the process of gravity sedimentation of a cloud of monodispersed solid spherical particles with initial volume concentration C > 0.03, which was performed in a wide range of Reynolds numbers. An analytical estimate of the settling regimes of spherical particle clouds is presented. A new method for creating a spherical particle cloud with a high concentration of particles is proposed. A qualitative picture of the settling process of a highly concentrated particle cloud under gravity is revealed. A criterial dependence for the drag coefficient of a sedimenting spherical particle cloud as an entity is obtained.

Modified resistivity-strain behavior through the incorporation of metallic particles in conductive polymer composite fibers containing carbon nanotubes

NARCIS (Netherlands)

Lin, L.; Deng, H.; Gao, X.; Zhang, S.M.; Bilotti, E.; Peijs, A.A.J.M.; Fu, Q.

2013-01-01

Eutectic metal particles and carbon nanotubes are incorporated into a thermoplastic polyurethane matrix through a simple but efficient method, melt compounding, to tune the resistivity-strain behavior of conductive polymer composite (CPC) fibers. Such a combination of conductive fillers is rarely

Mechanically Invisible Polymer Coatings

DEFF Research Database (Denmark)

2014-01-01

phase comprises particles, said particles comprising a filler material and an encapsulating coating of a second polymeric material, wherein the backbones of the first and second polymeric materials are the same. The composition may be used in electroactive polymers (EAPs) in order to obtain mechanically......The present invention relates to a composition comprising encapsulated particles in a polymeric material. The composition comprises a continuous phase and a discontinuous phase incorporated therein, wherein the continuous phase comprises a first polymeric material and wherein the discontinuous...... invisible polymer coatings....

Ultrasound-driven Megahertz Faraday Waves for Generation of Monodisperse Micro Droplets and Applications

Science.gov (United States)

Tsai, Chen S.; Mao, Rong W.; Lin, Shih K.; Tsai, Shirley C.; Boss, Gerry; Brenner, Matt; Smaldone, Gerry; Mahon, Sari; Shahverdi, Kaveh; Zhu, Yun

Our theoretical findings on instability of Faraday waves at megahertz (MHz) drive frequency and realization of silicon-based MHz multiple-Fourier horn ultrasonic nozzles (MFHUNs) together have enabled generation of mono-disperse droplets of controllable diameter (2.5-6.0 μm) at very low electrical drive power (generator has imminent application to pulmonary (inhalation) drug delivery and other potential applications. Here an update of advances on analysis and design of the MHz MFHUNs and the underlying physical mechanism for generation of mono-disperse micro droplets, and the nebulizer platform for application to detoxification of cyanide poisoning are presented.

Enzymatic Inverse Opal Hydrogel Particles for Biocatalyst.

Science.gov (United States)

Wang, Huan; Gu, Hongcheng; Chen, Zhuoyue; Shang, Luoran; Zhao, Ze; Gu, Zhongze; Zhao, Yuanjin

2017-04-19

Enzymatic carriers have a demonstrated value for chemical reactions and industrial applications. Here, we present a novel kind of inverse opal hydrogel particles as the enzymatic carriers. The particles were negatively replicated from spherical colloidal crystal templates by using magnetic nanoparticles tagged acrylamide hydrogel. Thus, they were endowed with the features of monodispersity, small volume, complete penetrating structure, and controllable motion, which are all beneficial for improving the efficiency of biocatalysis. In addition, due to the ordered porous nanostructure, the inverse opal hydrogel particles were imparted with unique photonic band gaps (PBGs) and vivid structural colors for encoding varieties of immobilized enzymes and for constructing a multienzymes biocatalysis system. These features of the inverse opal hydrogel particles indicate that they are ideal enzymatic carriers for biocatalysis.

Modified conductivity of polymer materials with proton beam

International Nuclear Information System (INIS)

Matsumoto, Shinji; Seki, Miharu; Shima, Kunihiro; Ishihara, Toyoyuki

2001-01-01

Ionic conductivity of polymer materials is of increasing interest in many scientific fields. Industrial applications seem to be promising. In the present investigation, we used proton bombardment to modify the characteristic properties of polymers, especially for improvement in conductivity and hardening gel polymers. Particle beam bombardment is known to produce many scissions by particle passages and new bonds by bridge connection. These effects may modify various properties in many ways. We examined the modification of conductivity in solid polymers composed of polyethylene oxide and polyurethane and the surface appearance of gel polymers with bombardment by a proton beam using the accelerator facility of Tsukuba University. The results indicated proton bombardment induced conductivity changes in various ways according to particle range and polymer properties. (author)

Physical characterization and in silico modeling of inulin polymer conformation during vaccine adjuvant particle formation.

Science.gov (United States)

Barclay, Thomas G; Rajapaksha, Harinda; Thilagam, Alagu; Qian, Gujie; Ginic-Markovic, Milena; Cooper, Peter D; Gerson, Andrea; Petrovsky, Nikolai

2016-06-05

This study combined physical data from synchrotron SAXS, FTIR and microscopy with in-silico molecular structure predictions and mathematical modeling to examine inulin adjuvant particle formation and structure. The results show that inulin polymer chains adopt swollen random coil in solution. As precipitation occurs from solution, interactions between the glucose end group of one chain and a fructose group of an adjacent chain help drive organized assembly, initially forming inulin ribbons with helical organization of the chains orthogonal to the long-axis of the ribbon. Subsequent aggregation of the ribbons results in the layered semicrystalline particles previously shown to act as potent vaccine adjuvants. γ-Inulin adjuvant particles consist of crystalline layers 8.5 nm thick comprising helically organized inulin chains orthogonal to the plane of the layer. These crystalline layers alternate with amorphous layers 2.4 nm thick, to give overall particle crystallinity of 78%. Copyright © 2016 Elsevier Ltd. All rights reserved.

Method of synthesizing tungsten nanoparticles

Science.gov (United States)

Thoma, Steven G; Anderson, Travis M

2013-02-12

A method to synthesize tungsten nanoparticles has been developed that enables synthesis of nanometer-scale, monodisperse particles that can be stabilized only by tetrahydrofuran. The method can be used at room temperature, is scalable, and the product concentrated by standard means. Since no additives or stabilizing surfactants are required, this method is particularly well suited for producing tungsten nanoparticles for dispersion in polymers. If complete dispersion is achieved due to the size of the nanoparticles, then the optical properties of the polymer can be largely maintained.

Rapid Synthesis of Highly Monodisperse Au x Ag 1− x Alloy Nanoparticles via a Half-Seeding Approach

KAUST Repository

Chng, Ting Ting

2011-05-03

Gold-silver alloy AuxAg1-x is an important class of functional materials promising new applications across a wide array of technological fields. In this paper, we report a fast and facile synthetic protocol for preparation of highly monodisperse AuxAg1-x alloy nanoparticles in the size range of 3-6 nm. The precursors employed in this work are M(I)-alkanethiolates (M = Au and Ag), which can be easily prepared by mixing common chemicals such as HAuCl4 or AgNO3 with alkanethiols at room temperature. In this half-seeding approach, one of the M(I)-alkanethiolates is first heated and reduced in oleylamine solvent, and freshly formed metal clusters will then act as premature seeds on which both the first and second metals (from M(I)-alkanethiolates, M = Au and Ag) can grow accordingly without additional nucleation and thus achieve high monodispersity for product alloy nanoparticles. Unlike in other prevailing methods, both Au and Ag elements present in these solid precursors are in the same monovalent state and have identical supramolecular structures, which may lead to a more homogeneous reduction and complete interdiffusion at elevated reaction temperatures. When the M(I)-alkanethiolates are reduced to metallic forms, the detached alkanethiolate ligands will serve as capping agent to control the growth. More importantly, composition, particle size, and optical properties of AuxAg1-x alloy nanoparticles can be conveniently tuned with this approach. The optical limiting properties of the prepared particles have also been investigated at 532 and 1064 nm using 7 ns laser pulses, which reveals that the as-prepared alloy nanoparticles exhibit outstanding broadband optical limiting properties with low thresholds. © 2011 American Chemical Society.

Synthesis and characterization of chemically ordered FePt magnetic nano-particles

Energy Technology Data Exchange (ETDEWEB)

Srinivasa Rao, K. [Centre for Materials for Electronics Technology (C-MET), IDA phase-III, Cherlapally, Hyderabad 500 051 (India); Balaji, T., E-mail: theerthambalaji@yahoo.co [Centre for Materials for Electronics Technology (C-MET), IDA phase-III, Cherlapally, Hyderabad 500 051 (India); Lingappa, Y. [Department of Chemistry, Sri Venkateswara University, Tirupati 517 502 (India); Reddy, M.R.P.; Kumar, Arbind; Prakash, T.L. [Centre for Materials for Electronics Technology (C-MET), IDA phase-III, Cherlapally, Hyderabad 500 051 (India)

2010-08-15

Monodispersed FePt alloy magnetic nano-particles are prepared by reduction of platinum acetyl acetonate and iron acetyl acetonate salts together in the presence of oleic acid and oleyl amine stabilizers by polyol process. The particle size of FePt is in the range of 2-3 nm confirmed by transmission electron microscopy (TEM). As-synthesized FePt nano-particles are chemically disordered with face centre cubic (fcc) structure where as after vacuum annealing these particles changed to face centre tetragonal (fct) ordered structure confirmed by the X-ray diffraction technique. Magnetic coercivity of 5.247 KOe was observed for fct structure.

The IBAS image analyser and its use in particle size measurement

International Nuclear Information System (INIS)

Snelling, K.W.

1984-10-01

The Kontron image analyser (IBAS) is used at Winfrith primarily for size analysis of aerosol particles. The system incorporates two computers, IBAS 1 for system communication and control, and IBAS 2 containing the main image memories. The first is accessed via a keyboard or digitiser tablet, and output can be displayed on a monitor or in printed form. The contents of the image memories are displayed on a colour monitor. Automatic image analysis is described, with typical applications, including the measurement of monodisperse particles, sodium fire aerosols, reactor crud particles and cadmium-silver aerosol particles. (U.K.)

μ-reactor measurements of catalytic activity of mass selected nano-particles

DEFF Research Database (Denmark)

Riedel, Jakob Nordheim

The work of this thesis revolves around catalytic activity measurements of nano-particles tested using a μ-reactor platform, developed and produced at DTU, in a collaboration between CINF and Nanotech. The thesis contains the results from two separate research projects; both utilising μ-reactors ......The work of this thesis revolves around catalytic activity measurements of nano-particles tested using a μ-reactor platform, developed and produced at DTU, in a collaboration between CINF and Nanotech. The thesis contains the results from two separate research projects; both utilising μ......-reactors in combination with surface science techniques and computer simulations. The first project described is a study of hydrogen dissociation on mono-disperse platinum clusters. The second project studies methanation from carbon monoxide and hydrogen on nano-particles of nickel-iron alloys. The second study is a work...... in progress, and the corresponding chapter aims to summarise the results so far. Other projects are not included in the thesis because they are inconclusive or dead ends. Hydrogen dissociation was studied by the H2/D2 exchange reaction on SiO2-supported mono-disperse platinum clusters in a -reactor...

Switching and memory effects in composite films of semiconducting polymers with particles of graphene and graphene oxide

Science.gov (United States)

Krylov, P. S.; Berestennikov, A. S.; Aleshin, A. N.; Komolov, A. S.; Shcherbakov, I. P.; Petrov, V. N.; Trapeznikova, I. N.

2015-08-01

The effects of switching were investigated in composite films based on multifunctional polymers. i.e., derivatives of carbazole (PVK) and fluorene (PFD), as well as based on particles of graphene (Gr) and graphene oxide (GO). The concentration of Gr and GO particles in the PVK(PFD) matrix was varied in the range of 2-3 wt %, which corresponded to the percolation threshold in these systems. The atomic composition of the composite films PVK: GO was examined using X-ray photoelectron spectroscopy. It was found that the effect of switching in structures of the form Al/PVK(PFD): GO(Gr)/ITO/PET manifests itself in a sharp change of the electrical resistance of the composite film from a low-conducting state to a relatively high-conducting state when applying a bias to Al-ITO electrodes of ˜0.1-0.3 V ( E ˜ 3-5 × 104 V/cm), which is below the threshold switching voltages for similar composites. The mechanism of resistance switching, which is associated with the processes of capture and accumulation of charge carriers by Gr (GO) particles introduced into the matrices of the high-molecular-weight (PVK) and relatively low-molecular-weight (PFD) polymers, was discussed.

Tritium containing polymers having a polymer backbone substantially void of tritium

Science.gov (United States)

Jensen, G.A.; Nelson, D.A.; Molton, P.M.

1992-03-31

A radioluminescent light source comprises a solid mixture of a phosphorescent substance and a tritiated polymer. The solid mixture forms a solid mass having length, width, and thickness dimensions, and is capable of self-support. In one aspect of the invention, the phosphorescent substance comprises solid phosphor particles supported or surrounded within a solid matrix by a tritium containing polymer. The tritium containing polymer comprises a polymer backbone which is essentially void of tritium. 2 figs.

Control of conducting polymer actuators without physical feedback: simulated feedback control approach with particle swarm optimization

International Nuclear Information System (INIS)

Xiang, Xingcan; Mutlu, Rahim; Alici, Gursel; Li, Weihua

2014-01-01

Conducting polymer actuators have shown significant potential in articulating micro instruments, manipulation devices, and robotics. However, implementing a feedback control strategy to enhance their positioning ability and accuracy in any application requires a feedback sensor, which is extremely large in size compared to the size of the actuators. Therefore, this paper proposes a new sensorless control scheme without the use of a position feedback sensor. With the help of the system identification technique and particle swarm optimization, the control scheme, which we call the simulated feedback control system, showed a satisfactory command tracking performance for the conducting polymer actuator’s step and dynamic displacement responses, especially under a disturbance, without needing a physical feedback loop, but using a simulated feedback loop. The primary contribution of this study is to propose and experimentally evaluate the simulated feedback control scheme for a class of the conducting polymer actuators known as tri-layer polymer actuators, which can operate both in dry and wet media. This control approach can also be extended to other smart actuators or systems, for which the feedback control based on external sensing is impractical. (paper)

Trends in Polymer and Particle Characterization by Microfluidic Field-Flow Fractionation Methods: Science or Business?

Czech Academy of Sciences Publication Activity Database

Janča, Josef; Sobota, Jaroslav

2014-01-01

Roč. 19, 16 May (2014), s. 296-308 ISSN 1023-666X R&D Projects: GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : Asymmetrical flow FFF * Electrical FFF * Field-flow fractionation * Flow FFF * Microelectrical FFF * Microfluidic channels * Microthermal FFF * Miniaturization and resolution * Polymers and particles separation * Sedimentation FFF * Technical benefits of microchannels * Thermal FFF Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.264, year: 2014

Interaction of Multiple Particles with a Solidification Front: From Compacted Particle Layer to Particle Trapping.

Science.gov (United States)

Saint-Michel, Brice; Georgelin, Marc; Deville, Sylvain; Pocheau, Alain

2017-06-13

The interaction of solidification fronts with objects such as particles, droplets, cells, or bubbles is a phenomenon with many natural and technological occurrences. For an object facing the front, it may yield various fates, from trapping to rejection, with large implications regarding the solidification pattern. However, whereas most situations involve multiple particles interacting with each other and the front, attention has focused almost exclusively on the interaction of a single, isolated object with the front. Here we address experimentally the interaction of multiple particles with a solidification front by performing solidification experiments of a monodisperse particle suspension in a Hele-Shaw cell with precise control of growth conditions and real-time visualization. We evidence the growth of a particle layer ahead of the front at a close-packing volume fraction, and we document its steady-state value at various solidification velocities. We then extend single-particle models to the situation of multiple particles by taking into account the additional force induced on an entering particle by viscous friction in the compacted particle layer. By a force balance model this provides an indirect measure of the repelling mean thermomolecular pressure over a particle entering the front. The presence of multiple particles is found to increase it following a reduction of the thickness of the thin liquid film that separates particles and front. We anticipate the findings reported here to provide a relevant basis to understand many complex solidification situations in geophysics, engineering, biology, or food engineering, where multiple objects interact with the front and control the resulting solidification patterns.

Tungsten atomic layer deposition on polymers

Energy Technology Data Exchange (ETDEWEB)

Wilson, C.A. [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215 (United States); McCormick, J.A. [Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309-0424 (United States); Cavanagh, A.S. [Department of Physics, University of Colorado, Boulder, Colorado 80309-0390 (United States); Goldstein, D.N. [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215 (United States); Weimer, A.W. [Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309-0424 (United States); George, S.M. [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215 (United States); Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309-0424 (United States)], E-mail: Steven.George@Colorado.Edu

2008-07-31

Tungsten (W) atomic layer deposition (ALD) was investigated on a variety of polymer films and polymer particles. These polymers included polyethylene, polyvinyl chloride, polystyrene, polycarbonate, polypropylene and polymethylmethacrylate. The W ALD was performed at 80 {sup o}C using WF{sub 6} and Si{sub 2}H{sub 6} as the gas phase reactants. W ALD on flat polymer films can eventually nucleate and grow after more than 60 AB cycles. X-ray photoelectron spectroscopy studies of W ALD on polystyrene after 50 AB cycles suggested that tungsten nanoclusters are present in the W ALD nucleation regime. The W ALD nucleation is greatly facilitated by a few cycles of Al{sub 2}O{sub 3} ALD. W ALD films were grown at 80 {sup o}C on spin-coated polymers on silicon wafers after 10 AB cycles of Al{sub 2}O{sub 3} ALD. The W ALD film was observed to grow linearly with a growth rate of 3.9 A per AB cycle on the polymer films treated with the Al{sub 2}O{sub 3} ALD seed layer. The W ALD films displayed an excellent, mirror-like optical reflectivity. The resistivity was 100-400 {mu}{omega} cm for W ALD films with thicknesses from 95-845 A. W ALD was also observed on polymer particles after W ALD in a rotary reactor. Without the Al{sub 2}O{sub 3} ALD seed layer, the nucleation of W ALD directly on the polymer particles at 80 {sup o}C required > 50 AB cycles. In contrast, the polymer particles treated with only 5 AB cycles of Al{sub 2}O{sub 3} ALD were observed to blacken after 25 AB cycles of W ALD. W ALD on polymers may have applications for flexible optical mirrors, electromagnetic interference shielding and gas diffusion barriers.

Highly Selective Synthesis of Catalytically Active Monodisperse Rhodium Nanocubes

Energy Technology Data Exchange (ETDEWEB)

Zhang, Y.; Grass, M.E.; Kuhn, J.N.; Tao, F.; Habas, S.E.; Huang, W.; Yang, P.; Somorjai, G.A.

2009-02-21

Synthesis of monodisperse and shape-controlled colloidal inorganic nanocrystals (NCs) is of increasing scientific interest and technological significance. Recently, shape control of Pt, Pd, Ag, Au, and Rh NCs has been obtained by tuning growth kinetics in various solution-phase approaches, including modified polyol methods, seeded growth by polyol reduction, thermolysis of organometallics, and micelle techniques. Control of reduction kinetics of the noble metal precursors and regulation of the relative growth rates of low-index planes (i.e. {l_brace}100{r_brace} and {l_brace}111{r_brace}) via selective adsorption of selected chemical species are two keys for achieving shape modification of noble metal NCs. One application for noble metal NCs of well-defined shape is in understanding how NC faceting (determines which crystallographic planes are exposed) affects catalytic performance. Rh NCs are used in many catalytic reactions, including hydrogenation, hydroformylation, hydrocarbonylation, and combustion reactions. Shape manipulation of Rh NCs may be important in understanding how faceting on the nanoscale affects catalytic properties, but such control is challenging and there are fewer reports on the shape control of Rh NCs compared to other noble metals. Xia and coworkers obtained Rh multipods exhibiting interesting surface plasmonic properties by a polyol approach. The Somorjai and Tilley groups synthesized crystalline Rh multipods, cubes, horns and cuboctahedra, via polyol seeded growth. Son and colleagues prepared catalytically active monodisperse oleylamine-capped tetrahedral Rh NCs for the hydrogenation of arenes via an organometallic route. More recently, the Somorjai group synthesized sizetunable monodisperse Rh NCs using a one-step polyol technique. In this Communication, we report the highly selective synthesis of catalytically active, monodisperse Rh nanocubes of < 10 nm by a seedless polyol method. In this approach, Br{sup -} ions from trimethyl

β-Cyclodextrin/thermosensitive containing polymer brushes grafted onto magnetite nano-particles for extraction and determination of venlafaxine in biological and pharmaceutical samples.

Science.gov (United States)

Ahmad Panahi, Homayon; Alaei, Haniyeh Sadat

2014-12-10

In this paper, a novel nano-sorbent is fabricated by the surface grafting of poly[β-CD/allylamine-co-N-isopropylacrylamide] onto modified magnetite nano-particles by 3-mercaptopropyltrimethoxysilane. The polymer grafted magnetite nano-particles was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, elemental analysis, scanning electron microscopy, and transmission electron microscopy. The feasibility of employing this nano-sorbent for extraction of trace venlafaxine in pharmaceutical samples and human biological fluids are investigated. The effect of various parameters such as pH, reaction temperature, and contact time was evaluated. The result revealed that the best sorption of venlafaxine by the magnetite nano-sorbent occurred at 35 °C at an optimum pH of 5. The kinetics of the venlafaxine shows accessibility of active sites in the grafted polymer onto the drug. The equilibrium data of venlafaxine by grafted magnetite nano-sorbent are well represented by the Langmuir and Freundlich isotherm models. The adsorption capacity of venlafaxine is found 142.8 mg g(-1) and indicated the homogeneous sites onto polymer grafted magnetite nano-sorbent surface. Nearly 80% of venlafaxine was released in simulated intestinal fluid, pH 7.4, in 30 h and 90% in simulated gastric fluid, pH 1.2, in 1 h. The venlafaxine loaded-polymer grafted magnetite nano-particles were successfully applied for the extraction in urine and pharmaceutical samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Settling of isolated particles and of suspensions in a shear-thinning medium; Sedimentation de particules isolees et de suspensions en milieu rheofluidifiant

Energy Technology Data Exchange (ETDEWEB)

Daugan, S.

2002-11-01

After drawing up a balance sheet of current knowledge of settling of particles and suspensions in Newtonian and non Newtonian fluids, we introduce the characterisation of the fluid-particles system and especially the shear-thinning behavior of Xanthan solutions. This experimental study is organised into two parts. First of all, we study the settling behavior of a few particles falling along their line of centres. The conditions for particles aggregation with respect to the rheological properties of the suspending fluid are systematically reported. To that extent, rheological relaxation experiments are performed. Once aggregated, the particles velocities are much more important that the velocity of a single one. We show that a simple model, based on the Newtonian case, allows to predict the position and the velocity of each particle with respect to the initial separation distance between them. The second part of this work is devoted to the study of the settling behavior of spherical and monodisperse particles suspensions according to the particles volume fraction, the polymer concentration of the suspending fluid and the geometry of the sedimenting cell. From a model giving the particle volume fraction as a function of the luminous intensity transmitted by the suspension, we show that three regimes of different kinetics occur. During the second regime, the particle volume fraction decreases exponentially with time and the observed phenomena are very fast. Finally, we study the spatial structuration of the suspension and we link it to the topography of the sediment obtained at the end of the sedimentation. (author)

Demagnetization factor for a powder of randomly packed spherical particles

DEFF Research Database (Denmark)

Bjørk, Rasmus; Bahl, Christian R.H.

2013-01-01

The demagnetization factors for randomly packed spherical particle powders with different porosities, sample aspect ratios, and monodisperse, normal, and log-normal particle size distributions have been calculated using a numerical model. For a relative permeability of 2, comparable to room...... temperature Gd, the calculated demagnetization factor is close to the theoretical value. The normalized standard deviation of the magnetization in the powder was 6.0%-6.7%. The demagnetization factor decreased significantly, while the standard deviation of the magnetization increased, for increasing relative...

Simple and inexpensive microfluidic devices for the generation of monodisperse multiple emulsions

KAUST Repository

Li, Erqiang

2013-12-16

Droplet-based microfluidic devices have become a preferred versatile platform for various fields in physics, chemistry and biology. Polydimethylsiloxane soft lithography, the mainstay for fabricating microfluidic devices, usually requires the usage of expensive apparatus and a complex manufacturing procedure. Here, we report the design and fabrication of simple and inexpensive microfluidic devices based on microscope glass slides and pulled glass capillaries, for generating monodisperse multiple emulsions. The advantages of our method lie in a simple manufacturing procedure, inexpensive processing equipment and flexibility in the surface modification of the designed microfluidic devices. Different types of devices have been designed and tested and the experimental results demonstrated their robustness for preparing monodisperse single, double, triple and multi-component emulsions. © 2014 IOP Publishing Ltd.

Effect of surfactant amount on the morphology and magnetic properties of monodisperse ZnFe{sub 2}O{sub 4} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Zhao, Haitao, E-mail: zht95711lunwen@163.com; Liu, Ruiping; Zhang, Qiang; Wang, Qiao

2016-03-15

Graphical abstract: Polyol process to monodisperse ZnFe{sub 2}O{sub 4} nanoparticles. - Highlights: • An one-step, facile and inexpensive synthetic route to monodisperse ZnFe{sub 2}O{sub 4} nanoparticles is described. • The sodium citrate stabilized ZnFe{sub 2}O{sub 4} nanoparticles with a diameter in the 5–8 nm size range can be easily dispersed in water. • The synthesis is very robust in terms of variations of experimental parameters. • ZnFe{sub 2}O{sub 4} nanoparticles present ferrimagnetic behavior at room temperature with a small hysteresis. - Abstract: The spinel ZnFe{sub 2}O{sub 4} ferrites with sodium citrate as a surfactant were fabricated by polyol process. The effect of surfactant amount on the structure, morphology and magnetic properties of ZnFe{sub 2}O{sub 4} ferrites were investigated by X-ray diffraction(XRD), transmission electron microscope (TEM), thermogravimetric and differential scanning calorimetry (TG–DSC) and vibrating sample magnetometry (VSM), respectively. The results indicate that the structure of ZnFe{sub 2}O{sub 4} ferrites is a pure cubic spinel structure with a particle size of 5–8 nm. The dispersion of the synthesized ZnFe{sub 2}O{sub 4} is enhanced when the mole ratio of Fe(acac){sub 3} to sodium citrate decreases. The synthesized particles present ferrimagnetic behavior with a small hysteresis at room temperature. The increase of surfactant amount conversely leads to the decrease in the saturation magnetization value (Ms) especially when the mole ratio of Fe(acac){sub 3} to sodium citrate decreases to 8:3. Its Ms value is drastically reduced to 18.97 emu/g.

A Convenient and Templated Method for the Fabrication of Monodisperse Micrometer Hollow Titania Spheres

Directory of Open Access Journals (Sweden)

Haibo Yao

2013-01-01

Full Text Available A simple and widely applicable methodology was presented to synthesize monodisperse micrometer hollow titania spheres (HTS based on the templating method. It was performed by using the preformed poly(styrene-acrylic acid (PSA as template spheres which was mixed with tetrabutyltitanate (TBOT in an ethanol solvent under steam treatment. The HTS which were obtained by the calcination of PSA/TiO2 composite core-shell spheres had a narrow particle size distribution and commendable surface topography characterized by SEM. The calcined HTS at 500°C displayed crystalline reflection peaks that were characteristic to the anatase phase by XRD. Moreover, some key influencing factors including TBOT concentration and reaction time were analyzed. As expected, the diameter of HTS could be readily controlled by altering the size of PSA template spheres. In addition, the approach was also applied to fabricate hollow zirconia spheres and other inorganic spheres.

Enteric-coated capsules filled with mono-disperse micro-particles containing PLGA-lipid-PEG nanoparticles for oral delivery of insulin.

Science.gov (United States)

Yu, Fei; Li, Yang; Liu, Chang Sheng; Chen, Qin; Wang, Gui Huan; Guo, Wei; Wu, Xue E; Li, Dong Hui; Wu, Winston Duo; Chen, Xiao Dong

2015-04-30

The success of the oral delivery of insulin (INS) as a therapeutic protein drug would significantly improve the quality of life of diabetic patients who would otherwise receive multiple daily INS injections. The oral delivery of INS, however, is still limited in its delivery efficiency, which could be due to the chemical, enzymatic, and adsorption barriers. In this work, in an attempt to improve the delivery efficiency, the INS-loaded polymer-lipid hybrid nanoparticles (INS-PLGA-lipid-PEG NPs) were designed and constructed through a double-emulsion solvent evaporation technique, followed by formulation of the spherical micro-particles using a spray freeze dryer (SFD). This kind of dryers has a uniquely designed microfluidic aerosol nozzle (MFAN), ensuring the formation of uniform particles. The resulted particles of ∼212 μm could easily be reverted to discrete INS-PLGA-lipid-PEG NPs in an aqueous solution. The INS-PLGA-lipid-PEG NPs created in this work showed a highly negative surface charge, excellent entrapment efficiency (92.3%) and a sustained drug release (∼24 h). Confocal laser scanning microscopy and flow cytometer were used to show that the cellular uptake efficiency for the INS-PLGA-lipid-PEG NPs was more effective than the INS in Caco-2 cells. More importantly, the in vivo pharmacodynamics demonstrated that the orally delivered system induced a prolonged decrease in blood glucose levels among diabetic rats. The relative bioavailability of INS compared with subcutaneous injection in diabetic rats was found to be approximately 12%. These results suggested that the encapsulated INS-PLGA-lipid-PEG NPs are promising and should be investigated further in the near future as an effective INS oral delivery system. Copyright © 2015. Published by Elsevier B.V.

Hybrid thin films derived from UV-curable acrylate-modified waterborne polyurethane and monodispersed colloidal silica

Directory of Open Access Journals (Sweden)

C. H. Yang

2012-01-01

Full Text Available Hybrid thin films containing nano-sized inorganic domains were synthesized from UV-curable acrylate-modified waterborne polyurethane (WPU-AC and monodispersed colloidal silica with coupling agent. The coupling agent, 3-(trimethoxysilylpropyl methacrylate (MSMA, was bonded onto colloidal silica first, and then mixed with WPU-AC to form a precursor solution. This precursor was spin coated, dried and UV-cured to generate the hybrid films. The silica content in the hybrid thin films was varied from 0 to 30 wt%. Experimental results showed the aggregation of silica particles in the hybrid films. Thus, the silica domain in the hybrid films was varied from 30 to 50 nm by the different ratios of MSMAsilica to WPU-AC. The prepared hybrid films from the crosslinked WPU-AC/MSMA-silica showed much better thermal stability and mechanical properties than pure WPU-AC.

The self-assembly of monodisperse nanospheres within microtubes

International Nuclear Information System (INIS)

Zheng Yuebing; Juluri, Bala Krishna; Huang, Tony Jun

2007-01-01

Self-assembled monodisperse nanospheres within microtubes have been fabricated and characterized. In comparison with colloidal crystals formed on planar substrates, colloidal nanocrystals self-assembled in microtubes demonstrate high spatial symmetry in their optical transmission and reflection properties. The dynamic self-assembly process inside microtubes is investigated by combining temporal- and spatial-spectrophotometric measurements. The understanding of this process is achieved through both experimentally recorded reflection spectra and finite difference time domain (FDTD)-based simulation results

Flexible high-loading particle-reinforced polyurethane magnetic nanocomposite fabrication through particle-surface-initiated polymerization

International Nuclear Information System (INIS)

Guo Zhanhu; Park, Sung; Wei Suying; Pereira, Tony; Moldovan, Monica; Karki, Amar B; Young, David P; Hahn, H Thomas

2007-01-01

Flexible high-loading nanoparticle-reinforced polyurethane magnetic nanocomposites fabricated by the surface-initiated polymerization (SIP) method are reported. Extensive field emission scanning electron microscopic (SEM) and atomic force microscopic (AFM) observations revealed a uniform particle distribution within the polymer matrix. X-ray photoelectron spectrometry (XPS) and differential thermal analysis (DTA) revealed a strong chemical bonding between the nanoparticles and the polymer matrix. The elongation of the SIP nanocomposite under tensile test was about four times greater than that of the composite fabricated by a conventional direct mixing fabrication method. The nanocomposite shows particle-loading-dependent magnetic properties, with an increase of coercive force after the magnetic nanoparticles were embedded into the polymer matrix, arising from the increased interparticle distance and the introduced polymer-particle interactions

Monodisperse Magneto-Fluorescent Bifunctional Nanoprobes for Bioapplications

Science.gov (United States)

Zhang, Hongwang; Huang, Heng; Pralle, Arnd; Zeng, Hao

2013-03-01

We present the work on the synthesis of dye-doped monodisperse Fe/SiO2 core/shell nanoparticles as bifunctional probes for bioapplications. Magnetic nanoparticles (NP) have been widely studied as nano-probes for bio-imaging, sensing as well as for cancer therapy. Among all the NPs, Fe NPs have been the focus because they have very high magnetization. However, Fe NPs are usually not stable in ambient due to the fast surface oxidation of the NPs. On the other hand, dye molecules have long been used as probes for bio-imaging. But they are sensitive to environmental conditions. It requires passivation for both so that they can be stable for applications. In this work, monodisperse Fe NPs with sizes ranging from 13-20 nm have been synthesized through the chemical thermal-decomposition in a solution. Silica shells were then coated on the Fe NPs by a two-phase oil-in-water method. Dye molecules were first bonded to a silica precursor and then encapsulated into the silica shell during the coating process. The silica shells protect both the Fe NPs and dye molecules, which makes them as robust probes. The dye doped Fe/SiO2 core/shell NPs remain both highly magnetic and highly fluorescent. The stable dye doped Fe/SiO2NPs have been used as a dual functional probe for both magnetic heating and local nanoscale temperature sending, and their performance will be reported. Research supported by NSF DMR 0547036, DMR1104994.

Photonic polymer-blend structures and method for making

Science.gov (United States)

Barnes, Michael D.

2004-06-29

The present invention comprises the formation of photonic polymer-blend structures having tunable optical and mechanical properties. The photonic polymer-blend structures comprise monomer units of spherical microparticles of a polymer-blend material wherein the spherical microparticles have surfaces partially merged with one another in a robust inter-particle bond having a tunable inter-particle separation or bond length sequentially attached in a desired and programmable architecture. The photonic polymer-blend structures of the present invention can be linked by several hundred individual particles sequentially linked to form complex three-dimensional structures or highly ordered two-dimensional arrays of 3D columns with 2D spacing.

Controllable dielectric and electrical performance of polymer composites with novel core/shell-structured conductive particles through biomimetic method

International Nuclear Information System (INIS)

Yang, Dan; Tian, Ming; Wang, Wencai; Li, Dongdong; Li, Runyuan; Liu, Haoliang; Zhang, Liqun

2013-01-01

Highlights: ► Conductive core/shell-structured particles were synthesized by biomimetic method. ► These particles with silica/poly(dopamine)/silver core and poly(dopamine) shell. ► Dielectric composites were prepared with resulted particles and silicone elastomer. ► The dielectric properties of the composites can be controlled by shell thickness. ► This biomimetic method is simple, nontoxic, efficient and easy to control. - Abstract: Novel silica/poly(dopamine)/silver (from inner to outer) (denoted as SiO 2 /PDA/Ag) conductive micro-particles were first synthesized by biomimetic poly(dopamine) coating. These micro-particles were then coated with a poly(dopamine) layer to form core/shell-structured particles, with silica/poly(dopamine)/silver core and poly(dopamine) shell (denoted as SiO 2 /PDA/Ag/PDA). This multilayer core/shell micro-particles were confirmed by scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and transmission electron microscope. Polymer composites were then prepared by mechanical blending of poly(dimethyl siloxane) and the core/shell-structured particles. It was found that the silver layer and the poly(dopamine) shell had good adhesion with substrate and they kept intact even under violent shearing stress during mechanical mixing. The effect of the thickness of outermost poly(dopamine) shell as well as the loading amount of this filler on the dielectric and electrical properties of the composites was further studied. The results showed that the dielectric constant, dielectric loss, and conductivity of the composites decreased with increasing shell thickness (10–53 nm) at the same loading level. And the maximal dielectric constant of composites was achieved in the composites filled with SiO 2 /PDA/Ag/PDA (with 10–15 nm PDA shell) particles, which was much larger than that of the composite filled with SiO 2 /PDA/Ag particles without insulative PDA shell. At the same time, the composites can change

Superficially porous particles with 1000Å pores for large biomolecule high performance liquid chromatography and polymer size exclusion chromatography.

Science.gov (United States)

Wagner, Brian M; Schuster, Stephanie A; Boyes, Barry E; Shields, Taylor J; Miles, William L; Haynes, Mark J; Moran, Robert E; Kirkland, Joseph J; Schure, Mark R

2017-03-17

To facilitate mass transport and column efficiency, solutes must have free access to particle pores to facilitate interactions with the stationary phase. To ensure this feature, particles should be used for HPLC separations which have pores sufficiently large to accommodate the solute without restricted diffusion. This paper describes the design and properties of superficially porous (also called Fused-Core ® , core shell or porous shell) particles with very large (1000Å) pores specifically developed for separating very large biomolecules and polymers. Separations of DNA fragments, monoclonal antibodies, large proteins and large polystyrene standards are used to illustrate the utility of these particles for efficient, high-resolution applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of particle size and porosity on in vivo remodeling of settable allograft bone/polymer composites.

Science.gov (United States)

Prieto, Edna M; Talley, Anne D; Gould, Nicholas R; Zienkiewicz, Katarzyna J; Drapeau, Susan J; Kalpakci, Kerem N; Guelcher, Scott A

2015-11-01

Established clinical approaches to treat bone voids include the implantation of autograft or allograft bone, ceramics, and other bone void fillers (BVFs). Composites prepared from lysine-derived polyurethanes and allograft bone can be injected as a reactive liquid and set to yield BVFs with mechanical strength comparable to trabecular bone. In this study, we investigated the effects of porosity, allograft particle size, and matrix mineralization on remodeling of injectable and settable allograft/polymer composites in a rabbit femoral condyle plug defect model. Both low viscosity and high viscosity grafts incorporating small (<105 μm) particles only partially healed at 12 weeks, and the addition of 10% demineralized bone matrix did not enhance healing. In contrast, composite grafts with large (105-500 μm) allograft particles healed at 12 weeks postimplantation, as evidenced by radial μCT and histomorphometric analysis. This study highlights particle size and surface connectivity as influential parameters regulating the remodeling of composite bone scaffolds. © 2015 Wiley Periodicals, Inc.

Application of dimensional regularization to single chain polymer static properties: Conformational space renormalization of polymers. III

International Nuclear Information System (INIS)

Oono, Y.; Ohta, T.; Freed, K.F.

1981-01-01

A dimensional regularization approach to the renormalization group treatment of polymer excluded volume is formulated in chain conformation space where monomers are specified by their spatial positions and their positions along the chain and the polymers may be taken to be monodisperse. The method utilizes basic scale invariance considerations. First, it is recognized that long wavelength macroscopic descriptions must be well defined in the limit that the minimum atomic or molecular scale L is set to zero. Secondly, the microscopic theory is independent of the conveniently chosen macroscopic scale of length k. The freedom of choice of k is exploited along with the assumed renormalizability of the theory to provide the renormalization group equations which directly imply the universal scaling laws for macroscopic properties. The renormalizability of the model implies the existence of the general relations between the basic macroparameters, such as chain length, excluded volume, etc., and their microscopic counterparts in the microscopic model for the system. These macro--micro relations are defined through the condition that macroscopic quantities be well defined for polymer chains for any spatial dimensionality. The method is illustrated by calculating the end vector distribution function for all values of end vectors R. The evaluation of this distribution function currently requires the use of expansions in e = 4-d. In this case our distribution reduces to known limits for R→0 or infinity. Subsequent papers will present calculations of the polymer coherent scattering function, the monomer spatial distribution function, and concentration dependent properties

Characterizing uranium oxide reference particles for isotopic abundances and uranium mass by single particle isotope dilution mass spectrometry

International Nuclear Information System (INIS)

Kraiem, M.; Richter, S.; Erdmann, N.; Kühn, H.; Hedberg, M.; Aregbe, Y.

2012-01-01

Highlights: ► A method to quantify the U mass in single micron particles by ID-TIMS was developed. ► Well-characterized monodisperse U-oxide particles produced by an aerosol generator were used. ► A linear correlation between the mass of U and the volume of particle(s) was found. ► The method developed is suitable for determining the amount of U in a particulate reference material. - Abstract: Uranium and plutonium particulate test materials are becoming increasingly important as the reliability of measurement results has to be demonstrated to regulatory bodies responsible for maintaining effective nuclear safeguards. In order to address this issue, the Institute for Reference Materials and Measurements (IRMM) in collaboration with the Institute for Transuranium Elements (ITU) has initiated a study to investigate the feasibility of preparing and characterizing a uranium particle reference material for nuclear safeguards, which is finally certified for isotopic abundances and for the uranium mass per particle. Such control particles are specifically required to evaluate responses of instruments based on mass spectrometric detection (e.g. SIMS, TIMS, LA-ICPMS) and to help ensuring the reliability and comparability of measurement results worldwide. In this paper, a methodology is described which allows quantifying the uranium mass in single micron particles by isotope dilution thermal ionization mass spectrometry (ID-TIMS). This methodology is characterized by substantial improvements recently achieved at IRMM in terms of sensitivity and measurement accuracy in the field of uranium particle analysis by TIMS. The use of monodisperse uranium oxide particles prepared using an aerosol generation technique developed at ITU, which is capable of producing particles of well-characterized size and isotopic composition was exploited. The evidence of a straightforward correlation between the particle volume and the mass of uranium was demonstrated in this study

Enhanced performance of P(VDF-HFP)-based composite polymer electrolytes doped with organic-inorganic hybrid particles PMMA-ZrO2 for lithium ion batteries

Science.gov (United States)

Xiao, Wei; Wang, Zhiyan; Zhang, Yan; Fang, Rui; Yuan, Zun; Miao, Chang; Yan, Xuemin; Jiang, Yu

2018-04-01

To improve the ionic conductivity as well as enhance the mechanical strength of the gel polymer electrolyte, poly(vinylidene fluoride-hexafluoroprolene) (P(VDF-HFP))-based composite polymer electrolyte (CPE) membranes doped with the organic-inorganic hybrid particles poly(methyl methacrylate) -ZrO2 (PMMA-ZrO2) are prepared by phase inversion method, in which PMMA is successfully grafted onto the surface of the homemade nano-ZrO2 particles via in situ polymerization confirmed by FT-IR. XRD and DSC patterns show adding PMMA-ZrO2 particles into P(VDF-HFP) can significantly decrease the crystallinity of the CPE membrane. The CPE membrane doped with 5 wt % PMMA-ZrO2 particles can not only present a homogeneous surface with abundant interconnected micro-pores, but maintain its initial shape after thermal exposure at 160 °C for 1 h, in which the ionic conductivity and lithium ion transference number at room temperature can reach to 3.59 × 10-3 S cm-1 and 0.41, respectively. The fitting results of the EIS plots indicate the doped PMMA-ZrO2 particles can significantly lower the interface resistance and promote lithium ions diffusion rate. The Li/CPE-sPZ/LiCoO2 and Li/CPE-sPZ/Graphite coin cells can deliver excellent rate and cycling performance. Those results suggest the P(VDF-HFP)-based CPE doped with 5 wt % PMMA-ZrO2 particles can become an exciting potential candidate as polymer electrolyte for the lithium ion battery.

Sonochemical synthesis of (3-aminopropyl)triethoxysilane-modified monodispersed silica nanoparticles for protein immobilization

International Nuclear Information System (INIS)

Shen, Shou-Cang; Ng, Wai Kiong; Chia, Leonard; Dong, Yuan-Cai; Tan, Reginald B.H.

2011-01-01

Graphical abstract: 3-Aminopropyltriethoxysilane modified monodispersed silica nanoparticles were synthesized by rapid sonochemical co-condensation to achieve high capability for protein immobilization. Highlights: → Amino-modified monodispersed silica nanoparticles were synthesized by rapid co-condensation. → Strong positive charge was created by aminopropyl-modification. → Capability for immobilization of negatively charged protein was enhanced. → Electrostatic interaction between proteins and surface contributed to the enhanced adsorption. -- Abstract: 3-Aminopropyltriethoxysilane modified monodispersed silica nanoparticles were synthesized by a rapid sonochemical co-condensation synthesis procedure. The chemical nature of surface organic modifier on the obtained modified silica nanoparticle was characterized by 13 C and 29 Si MAS Nuclear Magnetic Resonance (NMR) spectroscopies, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA)- differential scanning calorimetry (DSC). Due to the strengthened positive surface charge of the silica nanoparticles by the modification with aminopropyl groups, the capability for bovine serum albumin (BSA) adsorption was significantly increased as compared with bare silica nanoparticles. 80 mg/g BSA was adsorbed on modified silica nanoparticles, whereas only 20 mg/g BSA could be loaded on pure silica nanoparticles. The enhanced positive surface charge repelled proteins with net positive charge and the modified silica nanoparticles exhibited negligible adsorption of lysozyme, thus a selective adsorption of proteins could be achieved.

Sonochemical synthesis of (3-aminopropyl)triethoxysilane-modified monodispersed silica nanoparticles for protein immobilization

Energy Technology Data Exchange (ETDEWEB)

Shen, Shou-Cang, E-mail: shen_shoucang@ices.a-star.edu.sg [Institute of Chemical and Engineering Sciences, A-STAR (Agency for Science, Technology and Research), 1 Pesek Road, Jurong Island, Singapore 627833 (Singapore); Ng, Wai Kiong; Chia, Leonard; Dong, Yuan-Cai [Institute of Chemical and Engineering Sciences, A-STAR (Agency for Science, Technology and Research), 1 Pesek Road, Jurong Island, Singapore 627833 (Singapore); Tan, Reginald B.H., E-mail: reginald_tan@ices.a-star.edu.sg [Institute of Chemical and Engineering Sciences, A-STAR (Agency for Science, Technology and Research), 1 Pesek Road, Jurong Island, Singapore 627833 (Singapore); Department of Chemical and Biomolecular Engineering, The National University of Singapore, 4 Engineering Drive 4, Singapore 117576 (Singapore)

2011-10-15

Graphical abstract: 3-Aminopropyltriethoxysilane modified monodispersed silica nanoparticles were synthesized by rapid sonochemical co-condensation to achieve high capability for protein immobilization. Highlights: {yields} Amino-modified monodispersed silica nanoparticles were synthesized by rapid co-condensation. {yields} Strong positive charge was created by aminopropyl-modification. {yields} Capability for immobilization of negatively charged protein was enhanced. {yields} Electrostatic interaction between proteins and surface contributed to the enhanced adsorption. -- Abstract: 3-Aminopropyltriethoxysilane modified monodispersed silica nanoparticles were synthesized by a rapid sonochemical co-condensation synthesis procedure. The chemical nature of surface organic modifier on the obtained modified silica nanoparticle was characterized by {sup 13}C and {sup 29}Si MAS Nuclear Magnetic Resonance (NMR) spectroscopies, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA)- differential scanning calorimetry (DSC). Due to the strengthened positive surface charge of the silica nanoparticles by the modification with aminopropyl groups, the capability for bovine serum albumin (BSA) adsorption was significantly increased as compared with bare silica nanoparticles. 80 mg/g BSA was adsorbed on modified silica nanoparticles, whereas only 20 mg/g BSA could be loaded on pure silica nanoparticles. The enhanced positive surface charge repelled proteins with net positive charge and the modified silica nanoparticles exhibited negligible adsorption of lysozyme, thus a selective adsorption of proteins could be achieved.

The necessity of microscopy to characterize the optical properties of size-selected, nonspherical aerosol particles.

Science.gov (United States)

Veghte, Daniel P; Freedman, Miriam A

2012-11-06

It is currently unknown whether mineral dust causes a net warming or cooling effect on the climate system. This uncertainty stems from the varied and evolving shape and composition of mineral dust, which leads to diverse interactions of dust with solar and terrestrial radiation. To investigate these interactions, we have used a cavity ring-down spectrometer to study the optical properties of size-selected calcium carbonate particles, a reactive component of mineral dust. The size selection of nonspherical particles like mineral dust can differ from spherical particles in the polydispersity of the population selected. To calculate the expected extinction cross sections, we use Mie scattering theory for monodisperse spherical particles and for spherical particles with the polydispersity observed in transmission electron microscopy images. Our results for calcium carbonate are compared to the well-studied system of ammonium sulfate. While ammonium sulfate extinction cross sections agree with Mie scattering theory for monodisperse spherical particles, the results for calcium carbonate deviate at large and small particle sizes. We find good agreement for both systems, however, between the calculations performed using the particle images and the cavity ring-down data, indicating that both ammonium sulfate and calcium carbonate can be treated as polydisperse spherical particles. Our results indicate that having an independent measure of polydispersity is essential for understanding the optical properties of nonspherical particles measured with cavity ring-down spectroscopy. Our combined spectroscopy and microscopy techniques demonstrate a novel method by which cavity ring-down spectroscopy can be extended for the study of more complex aerosol particles.

Simple and inexpensive microfluidic devices for the generation of monodisperse multiple emulsions

KAUST Repository

Li, Erqiang; Zhang, Jiaming; Thoroddsen, Sigurdur T

2013-01-01

of expensive apparatus and a complex manufacturing procedure. Here, we report the design and fabrication of simple and inexpensive microfluidic devices based on microscope glass slides and pulled glass capillaries, for generating monodisperse multiple emulsions

Tribological characteristics of monodispersed cerium borate nanospheres in biodegradable rapeseed oil lubricant

Energy Technology Data Exchange (ETDEWEB)

Boshui, Chen, E-mail: boshuichen@163.com; Kecheng, Gu; Jianhua, Fang; Jiang, Wu; Jiu, Wang; Nan, Zhang

2015-10-30

Graphical abstract: - Highlights: • Monodispersed stearic acid-capped cerium borate composite nanoparticles were prepared by hydrothermal method. Their morphologies, element compositions, size distributions, crystal and chemical structures, hydrophobic characteristics were also characterized. • The surface-capped cerium borate nanoparticles exhibited excellent dispersing stability in rapeseed oil. As new lubricating additives, they were also outstanding in enhancing friction-reducing and anti-wear capacities of rapeseed oil in biodegradable rapeseed oil. The results presented in this paper would be of important significance for developing green lubricants and lubricant additives. • The prominent tribological performances of SA/CeBO{sub 3} in rapeseed oil were investigated and attributed to the formation of a composite boundary lubrication film mainly composed of lubricous tribochemical species on the tribo-surfaces. - Abstract: Stearic acid-capped cerium borate composite nanoparticles, abbreviated as SA/CeBO{sub 3}, were prepared by hydrothermal method. The morphologies, element compositions, size distributions, crystal and chemical structures, hydrophobic characteristics, of SA/CeBO{sub 3} were characterized by scanning electron microscope, energy dispersive X-ray spectrometer, dynamic laser particle size analyzer, X-ray diffraction, and Fourier transform infrared spectrometer, respectively. The friction and wear performances of SA/CeBO{sub 3} as a lubricating additive in a rapeseed oil were evaluated on a four-ball tribo-tester. The tribochemical characteristics of the worn surfaces were investigated by X-ray photoelectron spectroscopy. The results showed that the hydrophobic SA/CeBO{sub 3} were monodispersed nanospheres with an average diameter of 8 nm, and exhibited excellent dispersing stability in rapeseed oil. Meanwhile, SA/CeBO{sub 3} nanospheres were outstanding in enhancing friction-reducing and anti-wear capacities of rapeseed oil. The prominent

High performance of visible-NIR broad spectral photocurrent application of monodisperse PbSe nanocubes decorated on rGO sheets

Science.gov (United States)

Ghorban Shiravizadeh, A.; Elahi, S. M.; Sebt, S. A.; Yousefi, Ramin

2018-02-01

In this work, the photoresponse performance of monodisperse PbSe nanocubes in the range of visible and near-infrared (NIR) (400-1500 nm) regions was enhanced by reduced graphene oxide (rGO). A simple cost-effective method is presented to synthesize monodisperse PbSe nanocubes (NCs) that are decorated on the rGO sheets. By the addition of PbSe/rGO nanocomposites with different rGO concentrations, pristine PbSe NCs were synthesized with the same method. Microscopy images showed that the size of NCs was smaller than the exciton Bohr radius (46 nm) of PbSe bulk. Therefore, the UV-Vis-IR spectroscopy result revealed that the PbSe/rGO samples had absorption peaks in the NIR region around 1650 nm and showed a blue shift compared to the absorption peak of the PbSe bulk. J-V measurements of the samples indicated that monodisperse PbSe/rGO nanocomposites had a higher resistance than the other samples under dark condition. On the other hand, the resistance of the monodisperse PbSe/rGO nanocomposites decreased under different light source illuminations while the resistance of the other samples was increased under illumination. Photodetector measurements indicated that the monodisperse morphology of the PbSe NCs enhanced the photoresponse speed and photocurrent intensity. In addition, responsivity (R) and detectivity (D*) of the samples were higher in the NIR region.

The critical particle size for enhancing thermal conductivity in metal nanoparticle-polymer composites

Science.gov (United States)

Lu, Zexi; Wang, Yan; Ruan, Xiulin

2018-02-01

Polymers used as thermal interface materials are often filled with high-thermal conductivity particles to enhance the thermal performance. Here, we have combined molecular dynamics and the two-temperature model in 1D to investigate the impact of the metal filler size on the overall thermal conductivity. A critical particle size has been identified above which thermal conductivity enhancement can be achieved, caused by the interplay between high particle thermal conductivity and the added electron-phonon and phonon-phonon thermal boundary resistance brought by the particle fillers. Calculations on the SAM/Au/SAM (self-assembly-monolayer) system show a critical thickness Lc of around 10.8 nm. Based on the results, we define an effective thermal conductivity and propose a new thermal circuit analysis approach for the sandwiched metal layer that can intuitively explain simulation and experimental data. The results show that when the metal layer thickness decreases to be much smaller than the electron-phonon cooling length (or as the "thin limit"), the effective thermal conductivity is just the phonon portion, and electrons do not participate in thermal transport. As the thickness increases to the "thick limit," the effective thermal conductivity recovers the metal bulk value. Several factors that could affect Lc are discussed, and it is discovered that the thermal conductivity, thermal boundary resistance, and the electron-phonon coupling factor are all important in controlling Lc.

Nano-sized particles, processes of making, compositions and uses thereof

Science.gov (United States)

O'Brien, Stephen [New York, NY; Yin, Ming [Los Alamos, NM

2012-05-22

The present invention describes methods for preparing high quality nanoparticles, i.e., metal oxide based nanoparticles of uniform size and monodispersity. The nanoparticles advantageously comprise organic alkyl chain capping groups and are stable in air and in nonpolar solvents. The methods of the invention provide a simple and reproducible procedure for forming transition metal oxide nanocrystals, with yields over 80%. The highly crystalline and monodisperse nanocrystals are obtained directly without further size selection; particle size can be easily and fractionally increased by the methods. The resulting nanoparticles can exhibit magnetic and/or optical properties. These properties result from the methods used to prepare them. Also advantageously, the nanoparticles of this invention are well suited for use in a variety of industrial applications, including cosmetic and pharmaceutical formulations and compositions.

Luminescent nanocomposites of conducting polymers and in-situ grown CdS quantum dots

International Nuclear Information System (INIS)

Borriello, C.; Masala, S.; Nenna, G.; Minarini, C.; Di Luccio, T.; Bizzarro, V.; Re, M.; Pesce, E.

2010-01-01

Luminescent PVK:CdS and P3HT:CdS nanocomposites with enhanced electrooptical properties have been synthesized. The nucleation and growth of CdS nanoparticles have been obtained by the thermolysis of a single Cd and S precursor dispersed in the polymers. The size distribution and morphology of the nanoparticles have been studied by TEM analyses. Monodispersive and very small nanoparticles of diameter below 3 nm in PVK and 2 nm in P3HT, have been obtained. The application of such nanocomposites as emitting layers in OLED devices is discussed.

Rheological behavior study of a clay-polymer mixture: effects of the polymer addition

International Nuclear Information System (INIS)

Benchabane, A.

2006-11-01

The aim of the present work is to establish a bibliographical synthesis on the microstructure, the colloidal and rheological characterization of bentonite suspensions with and without polymer/surfactant addition; to lead to a rheological characterization of clay-additive mixtures and to understand the interaction between the clay particles and polymer/surfactants. Different experimental measurements: rheology, particle sizing, and x-ray diffraction were used to study the rheological character of the water-bentonite-anionic additive mixtures (CMC, SDS, xanthane) as well as the nature of the particle-particle interactions and particle-additive. The modeling part led to the adoption of Tiu and Boger's model to predict the thixotropy of the bentonite suspensions without additive. Thus, a new model is proposed with physical parameters for a better correlation of the rheological behavior of the various studied mixtures. (author)

Role of surface functionality on the formation of raspberry-like polymer/silica composite particles: Weak acid–base interaction and steric effect

International Nuclear Information System (INIS)

Wang, Lan; Song, LinYong; Chao, ZhiYin; Chen, PengPeng; Nie, WangYan; Zhou, YiFeng

2015-01-01

Graphical abstract: - Highlights: • Core–shell structured polymer/SiO 2 was obtained with carboxylic-functionalized templates. • Raspberry-like structure was observed with carboxylic and poly(ethylene glycol) hybrid-functionalized polymer microspheres. • Carboxylic groups contributed to the nucleation and the poly(ethylene glycol) chains was used to control the growth of silica particles. • Super-hydrophobic surface was obtained and the contact angle of water on the dual-sized structured surface was up to 160°. - Abstract: The surface functionality of polymer microspheres is the crucial factor to determine the nucleation and growth of silica particles and to construct the organic/inorganic hierarchical structures. The objective of this work was to evaluate the surface functionality and hierarchical morphology relationship via in situ sol–gel reaction. Carboxylic-functionalized poly (styrene-co-maleic anhydride) [P(S-co-MA)], poly(ethylene glycol)-functionalized poly(styrene-co-poly(ethylene glycol) methacrylate) [P(S-co-PEGMA)], and hybrid functionalized poly(styrene-co-maleic anhydride-co-poly(ethylene glycol) methacrylate) [P(S-co-MA-co-PEGMA)] microspheres were synthesized by emulsifier-free polymerization and used as templates. The morphologies of the composite particles were observed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results showed that core–shell structure was obtained with P(S-co-MA) as templates; raspberry-like structure was observed by using P(S-co-MA-co-PEGMA) as templates; and no silica particles were attached onto the surface of P(S-co-PEGMA) microspheres. These results indicated that the carboxylic groups on the surface formed by hydrolysis of anhydride groups were the determinate factor to control the nucleation of silica nanoparticles, and the PEG chains on the surface can affect the growth of silica particles. In addition, the particulate films were constructed by assembling these

Hybrid composites of monodisperse pi-conjugated rodlike organic compounds and semiconductor quantum particles

DEFF Research Database (Denmark)

Hensel, V.; Godt, A.; Popovitz-Biro, R.

2002-01-01

Composite materials of quantum particles (Q-particles) arranged in layers within crystalline powders of pi-conjugated, rodlike dicarboxylic acids are reported. The synthesis of the composites, either as three-dimensional crystals or as thin films at the air-water interface, comprises a two...... analysis of the solids and grazing incidence X-ray diffraction analysis of the films on water. 2) Topotactic solid/gas reaction of these salts with H2S to convert the metal ions into Q-particles of CdS or PbS embedded in the organic matrix that consists of the acids 6(H) and 8(H). These hybrid materials...

A study of the initiator concentration’s effect on styrene-divinylbenzene polymerization with iron particles

Directory of Open Access Journals (Sweden)

Bárbara M. da Conceição

2011-01-01

Full Text Available This paper describes the preparation of magnetic copolymer obtained from suspension polymerization of styrene (Sty and divinylbenzene (DVB in the presence of iron particles treated and not treated with oleic acid. The magnetic copolymers were characterized according to their morphology, particle size distribution and magnetic properties. The results show that incorporation of iron particles significantly changed the particles’ morphology. All samples presented higher saturation magnetization than the values reported in the literature and the particle size distribution was more monodisperse when the polymerization was conducted with 5%wt of benzoyl peroxide (BPO.

Preparation of spherical silver particles for solar cell electronic paste with gelatin protection

International Nuclear Information System (INIS)

Ao Yiwei; Yang Yunxia; Yuan Shuanglong; Ding Lihua; Chen Guorong

2007-01-01

Spherical silver particles used in electronic paste for solar cell were prepared using the chemical reduction method with ammonia as a complex agent, hydrazine hydrate as a reducing agent, and gelatin as a protective agent. The gelatin protective mechanism in the preparing process of spherical silver particles was studied. Observations of SEM and results of laser particle size analysis and ultraviolet absorption spectra demonstrate the formation of the coordinative complex of silver ions with gelatin in aqueous solution which accelerated the reduction of silver ions. Moreover, gelatin can promote the nucleation of the metallic silver particles, thus beneficiating availability of the monodisperse spherical silver particles

Heat Dissipation of Resonant Absorption in Metal Nanoparticle-Polymer Films Described at Particle Separation Near Resonant Wavelength

Directory of Open Access Journals (Sweden)

Jeremy R. Dunklin

2017-01-01

Full Text Available Polymer films containing plasmonic nanostructures are of increasing interest for development of responsive energy, sensing, and therapeutic systems. The present work evaluates heat dissipated from power absorbed by resonant gold (Au nanoparticles (NP with negligible Rayleigh scattering cross sections randomly dispersed in polydimethylsiloxane (PDMS films. Finite element analysis (FEA of heat transport was coordinated with characterization of resonant absorption by Mie theory and coupled dipole approximation (CDA. At AuNP particle separation greater than resonant wavelength, correspondence was observed between measured and CDA-predicted optical absorption and FEA-derived power dissipation. At AuNP particle separation less than resonant wavelength, measured extinction increased relative to predicted values, while FEA-derived power dissipation remained comparable to CDA-predicted power absorption before lagging observed extinguished power at higher AuNP content and resulting particle separation. Effects of isolated particles, for example, scattering, and particle-particle interactions, for example, multiple scattering, aggregation on observed optothermal activity were evaluated. These complementary approaches to distinguish contributions to resonant heat dissipation from isolated particle absorption and interparticle interactions support design and adaptive control of thermoplasmonic materials for a variety of implementations.

ADSORPTION BEHAVIOR OF PARTICLE IN POLYELECTROLYTE SOLUTION AND INTERACTION BETWEEN TWO PARTICLES ADSORBING POLYMER (I) MATHEMATICAL MODEL%粒子在溶液中吸附聚电解质行为及粒子间的相互作用(Ⅰ)模型建立

Institute of Scientific and Technical Information of China (English)

季君晖

2001-01-01

Mathematical models for particle adsorbing polymer chains from polyelelctrolyte solution and the interaction between two particles adsorbing polymer were derived by adopting predecessor-determined random walk model (PDRWM) on the basis of self-consistent field and statistical thermodynamics. The interactions among particle, polymer segment and solvent molecule, as well as the effect of charged groups in polymer chains were taken into account in these models. The profile of segment density distribution was derived. The change of free energy of the interaction between two particles adsorbing polymer was also derived according to the change in particle surface free energy.%以自洽场(CSF)理论为基础，综合粒子、溶剂分子和聚合物链节之间的相互作用及聚合物分子链电荷的作用对粒子在溶液中吸附聚合物的影响，采用前末端链节决定随机行走模型(PRDWM)建立了粒子在聚合物溶液中吸附平衡后的粒子表面的链节密度分布的数学模型——链节密度分布函数，并通过吸附前后粒子表面自由能的变化建立了吸附聚合物分子链的粒子间的相互作用势能模型.

Monodisperse and core-shell structured SiO{sub 2}-Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln=Eu, Tb, Dy, Sm, Er, Ho, and Tm) spherical particles: A facile synthesis and luminescent properties

Energy Technology Data Exchange (ETDEWEB)

Xu, Zhenhe, E-mail: xuzh056@163.com [College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang 100142 (China); Feng, Bin [China National Aviation Fuel Group Corporation, Planning and Development Department, Beijing 100088 (China); Bian, Shasha; Liu, Tao; Wang, Mingli; Gao, Yu; Sun, Di; Gao, Xin [College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang 100142 (China); Sun, Yaguang, E-mail: yaguangsun@yahoo.com.cn [College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang 100142 (China)

2012-12-15

The core-shell structured SiO{sub 2}-Lu{sub 2}O{sub 3}:Ln{sup 3+} particles were realized by coating the Lu{sub 2}O{sub 3}:Ln{sup 3+} phosphors onto the surface of non-aggregated, monodisperse and spherical SiO{sub 2} particles by the Pechini sol-gel method. The as-synthesized products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray (EDX) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photolumiminescence (PL), and low-voltage cathodoluminescence (CL). The results indicate that the 800 Degree-Sign C annealed sample consists of crystalline Lu{sub 2}O{sub 3} shells and amorphous SiO{sub 2} cores, in spherical shape with a narrow size distribution. The as-obtained particles show strong light emission with different colors corresponding to different Ln{sup 3+} ions under ultraviolet-visible light excitation and low-voltage electron beams excitation, which have potential applications in fluorescent lamps and field emission displays. - Graphical Abstract: Representative SEM and TEM images of the core-shell structured SiO{sub 2}-Lu{sub 2}O{sub 3}:Eu{sup 3+} particles; CIE chromaticity diagram showing the emission colors for SiO{sub 2}-Lu{sub 2}O{sub 3}:Ln{sup 3+}; Multicolor emissions of SiO{sub 2}-Lu{sub 2}O{sub 3}:Ln{sup 3+} particles. Highlights: Black-Right-Pointing-Pointer The core-shell particles were realized by coating the phosphors onto the surface of SiO{sub 2} particles. Black-Right-Pointing-Pointer The sample consists of crystalline Lu{sub 2}O{sub 3} shells and amorphous SiO{sub 2} cores. Black-Right-Pointing-Pointer The particles show different light emission colors corresponding to Ln{sup 3+} ions. Black-Right-Pointing-Pointer They have potential applications in fluorescent lamps and field emission displays.

Glass transition temperature of polymer nano-composites with polymer and filler interactions

Science.gov (United States)

Hagita, Katsumi; Takano, Hiroshi; Doi, Masao; Morita, Hiroshi

2012-02-01

We systematically studied versatile coarse-grained model (bead spring model) to describe filled polymer nano-composites for coarse-grained (Kremer-Grest model) molecular dynamics simulations. This model consists of long polymers, crosslink, and fillers. We used the hollow structure as the filler to describe rigid spherical fillers with small computing costs. Our filler model consists of surface particles of icosahedra fullerene structure C320 and a repulsive force from the center of the filler is applied to the surface particles in order to make a sphere and rigid. The filler's diameter is 12 times of beads of the polymers. As the first test of our model, we study temperature dependence of volumes of periodic boundary conditions under constant pressures through NPT constant Andersen algorithm. It is found that Glass transition temperature (Tg) decrease with increasing filler's volume fraction for the case of repulsive interaction between polymer and fillers and Tg weakly increase for attractive interaction.

Ni-polymer nanogel hybrid particles: A new strategy for hydrogen production from the hydrolysis of dimethylamine-borane and sodium borohydride

International Nuclear Information System (INIS)

Cai, Haokun; Liu, Liping; Chen, Qiang; Lu, Ping; Dong, Jian

2016-01-01

Efficient non-precious metal catalysts are crucial for hydrogen production from borohydride compounds in aqueous media via hydrogen atoms in water. A method for preparing magnetic polymer nanoparticles is developed in this study based on the chemical deposition of nickel onto hydrophilic polymer nanogels. High-resolution transmission electron microscopic and XPS analyses show that Ni exists mainly in the form of NiO in nanogels. Excellent catalytic activities of the nanoparticles are demonstrated for hydrogen generation from the hydrolysis of dimethylamine-borane and sodium borohydride in which the initial TOF (turn-over frequencies) are 376 and 1919 h"−"1, respectively. Kinetic studies also reveal an Arrhenius activation energy of 50.96 kJ mol"−"1 for the hydrolysis of dimethylamine-borane and 47.82 kJ mol"−"1 for the hydrolysis of sodium borohydride, which are lower than those catalyzed by Ru metal. Excellent reusability and the use of water for hydrogen production from dimethylamine-borane provide the additional benefit of using a hybrid catalyst. The principle illustrated in the present study offers a new strategy to explore polymer-transition metal hybrid particles for hydrogen energy technology. - Highlights: • Electroless Ni plating on polymer nanogels generated recyclable catalysts. • The Ni particles proved efficient for H_2 production from borohydride compounds. • The catalysts have lower activation energies than Ru for the hydrolysis. • Borohydride hydrolysis is more beneficial than dehydrogenation in organic solvent.

Thermodynamics of phase-separating nanoalloys: Single particles and particle assemblies

Science.gov (United States)

Fèvre, Mathieu; Le Bouar, Yann; Finel, Alphonse

2018-05-01

The aim of this paper is to investigate the consequences of finite-size effects on the thermodynamics of nanoparticle assemblies and isolated particles. We consider a binary phase-separating alloy with a negligible atomic size mismatch, and equilibrium states are computed using off-lattice Monte Carlo simulations in several thermodynamic ensembles. First, a semi-grand-canonical ensemble is used to describe infinite assemblies of particles with the same size. When decreasing the particle size, we obtain a significant decrease of the solid/liquid transition temperatures as well as a growing asymmetry of the solid-state miscibility gap related to surface segregation effects. Second, a canonical ensemble is used to analyze the thermodynamic equilibrium of finite monodisperse particle assemblies. Using a general thermodynamic formulation, we show that a particle assembly may split into two subassemblies of identical particles. Moreover, if the overall average canonical concentration belongs to a discrete spectrum, the subassembly concentrations are equal to the semi-grand-canonical equilibrium ones. We also show that the equilibrium of a particle assembly with a prescribed size distribution combines a size effect and the fact that a given particle size assembly can adopt two configurations. Finally, we have considered the thermodynamics of an isolated particle to analyze whether a phase separation can be defined within a particle. When studying rather large nanoparticles, we found that the region in which a two-phase domain can be identified inside a particle is well below the bulk phase diagram, but the concentration of the homogeneous core remains very close to the bulk solubility limit.

Protein cages and synthetic polymers: a fruitful symbiosis for drug delivery applications, bionanotechnology and materials science.

Science.gov (United States)

Rother, Martin; Nussbaumer, Martin G; Renggli, Kasper; Bruns, Nico

2016-11-07

Protein cages are hollow protein nanoparticles, such as viral capsids, virus-like particles, ferritin, heat-shock proteins and chaperonins. They have well-defined capsule-like structures with a monodisperse size. Their protein subunits can be modified by genetic engineering at predetermined positions, allowing for example site-selective introduction of attachment points for functional groups, catalysts or targeting ligands on their outer surface, in their interior and between subunits. Therefore, protein cages have been extensively explored as functional entities in bionanotechnology, as drug-delivery or gene-delivery vehicles, as nanoreactors or as templates for the synthesis of organic and inorganic nanomaterials. The scope of functionalities and applications of protein cages can be significantly broadened if they are combined with synthetic polymers on their surface or within their interior. For example, PEGylation reduces the immunogenicity of protein cage-based delivery systems and active targeting ligands can be attached via polymer chains to favour their accumulation in diseased tissue. Polymers within protein cages offer the possibility of increasing the loading density of drug molecules, nucleic acids, magnetic resonance imaging contrast agents or catalysts. Moreover, the interaction of protein cages and polymers can be used to modulate the size and shape of some viral capsids to generate structures that do not occur with native viruses. Another possibility is to use the interior of polymer cages as a confined reaction space for polymerization reactions such as atom transfer radical polymerization or rhodium-catalysed polymerization of phenylacetylene. The protein nanoreactors facilitate a higher degree of control over polymer synthesis. This review will summarize the hybrid structures that have been synthesized by polymerizing from protein cage-bound initiators, by conjugating polymers to protein cages, by embedding protein cages into bulk polymeric

Particle size dependence of the Young's modulus of filled polymers: 2. Annealing and solid-state nuclear magnetic resonance experiments

NARCIS (Netherlands)

Vollenberg, P.H.T.; Haan, de J.W.; Ven, van de L.J.M.; Heikens, D.

1989-01-01

Experimental results are reported from which it appears that in the case of polymer filled with silane-treated glass beads the Young's modulus is, in accordance with present theory, independent of the particle size of the filler. However, if pure glass beads are used as filler, the Young's modulus

Organic inorganic hybrid coating (poly(methyl methacrylate)/monodisperse silica)

Science.gov (United States)

Rubio, E.; Almaral, J.; Ramírez-Bon, R.; Castaño, V.; Rodríguez, V.

2005-04-01

Polymethylmethacrylate-silica hybrid coatings were prepared from methyl methacrylate and monodisperse colloidal silica prepared by the Stöber method. The surfaces of the spheres were successfully modified by chemical reaction with 3-(trimethoxysilyl) propyl methacrylate (TMSPM) to compatibilise the organic and inorganic components of the precursor solution mixture. The coatings were deposited by dip-coating on glass substrates. They result with good properties of homogeneity, optical transparence, hardness and adhesion.

Metal Fe3+ ions assisted synthesis of highly monodisperse Ag/SiO2 nanohybrids and their antibacterial activity

International Nuclear Information System (INIS)

Zhang, Nianchun; Xue, Feng; Yu, Xiang; Zhou, Huihua; Ding, Enyong

2013-01-01

Graphical abstract: TEM images of the Ag/SiO 2 -2 nanohybrids. The homogeneous and more mono-disperse Ag nanoparticles deposit on SiO 2 spheres. Through this method, Ag nanoparticles are easily formed on the surface of SiO 2 compared to other methods. Highlights: ► We prepared homogeneous and mono-dispersed Ag/SiO 2 -2 nanohybrids by adding Fe 3+ ions. ► The Ag/SiO 2 -2 nanohybrids had core(SiO 2 )-shell(Ag) structure. ► The Ag/SiO 2 -2 nanohybrids exhibited excellent antibacterial activity against bacteria. ► The reaction temperature was lower and the yield of Ag/SiO 2 -2 nanohybrids were higher. - Abstract: Highly monodispersed Ag/SiO 2 nanohybrids with excellent antibacterial property were synthesized by using DMF as a reducing agent and employing an additional redox potential of metal Fe 3+ ion as a catalytic agent. The obtained Ag/SiO 2 -2 nanohybrids of about 240 nm were highly monodispersity and uniformity by adding trace Fe 3+ ions into the reaction which Ag + reacted with N,N-dimethyl formamide (DMF) at 70 °C. Compared to the conventional techniques, which need long time and high temperature for silica coating of Ag nanoparticles, this new method was capable of synthesizing monodispersed, uniform, high yield Ag/SiO 2 nanohybrids. The electron was transferred from the Fe 2+ ion to the Ag + ion to accelerate the nucleation of silver nanoparticles. The chemical structures, morphologies and properties of the Ag/SiO 2 nanohybrids were characterized by X-ray diffraction (XRD), (High-resolution, Scanning transmission) transmission electron microscopy (TEM, HRTEM and STEM), and X-ray photoelectron spectroscopy (XPS), and UV–vis spectroscopy (UV–vis) and test of antibacterial. The results demonstrated that the silver nanoparticles supported on the surface of SiO 2 spheres in Ag/SiO 2 -2 nanohybrids structure, the Ag nanoparticles were homogeneous and monodispersed. The results also indicated that the Ag/SiO 2 -2 nanohybrid had excellent antibacterial.

Preparation and properties of hybrid direct methanol fuel cell membranes by embedding organophosphorylated titania submicrospheres into a chitosan polymer matrix

Energy Technology Data Exchange (ETDEWEB)

Wu, Hong [Key Laboratory for Green Chemical Technology, School of Chemical Engineering and Technology, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072 (China); Tianjin Key Laboratory of Membrane Science and Desalination Technology, Tianjin University, Tianjin 300072 (China); Hou, Weiqiang; Wang, Jingtao; Xiao, Lulu; Jiang, Zhongyi [Key Laboratory for Green Chemical Technology, School of Chemical Engineering and Technology, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072 (China)

2010-07-01

Organophosphorylated titania submicrospheres (OPTi) are prepared and incorporated into a chitosan (CS) matrix to fabricate hybrid membranes with enhanced methanol resistance and proton conductivity for application in direct methanol fuel cells (DMFC). The pristine monodispersed titania submicrospheres (TiO{sub 2}) of controllable particle size are synthesized through a modified sol-gel method and then phosphorylated by amino trimethylene phosphonic acid (ATMP) via chemical adsorption, which is confirmed by XPS, FTIR and TGA. The morphology and thermal property of the hybrid membranes are explored by SEM and TGA. The ionic cross-linking between the -PO{sub 3}H{sub 2} groups on OPTi and the -NH{sub 2} groups on CS lead to better compatibility between the inorganic fillers and the polymer matrix, as well as a decreased fractional free volume (FFV), which is verified by positron annihilation lifetime spectroscopy (PALS). The effects of particle size and content on the methanol permeability, proton conductivity, swelling and FFV of the membranes are investigated. Compared to pure CS membrane, the hybrid membranes exhibit an increased proton conductivity to an acceptable level of 0.01 S cm{sup -1} for DMFC application and a reduced methanol permeability of 5 x 10{sup -7} cm{sup 2} s{sup -1} at a 2 M methanol feed. (author)

Preparation and properties of hybrid direct methanol fuel cell membranes by embedding organophosphorylated titania submicrospheres into a chitosan polymer matrix

Science.gov (United States)

Wu, Hong; Hou, Weiqiang; Wang, Jingtao; Xiao, Lulu; Jiang, Zhongyi

Organophosphorylated titania submicrospheres (OPTi) are prepared and incorporated into a chitosan (CS) matrix to fabricate hybrid membranes with enhanced methanol resistance and proton conductivity for application in direct methanol fuel cells (DMFC). The pristine monodispersed titania submicrospheres (TiO 2) of controllable particle size are synthesized through a modified sol-gel method and then phosphorylated by amino trimethylene phosphonic acid (ATMP) via chemical adsorption, which is confirmed by XPS, FTIR and TGA. The morphology and thermal property of the hybrid membranes are explored by SEM and TGA. The ionic cross-linking between the -PO 3H 2 groups on OPTi and the -NH 2 groups on CS lead to better compatibility between the inorganic fillers and the polymer matrix, as well as a decreased fractional free volume (FFV), which is verified by positron annihilation lifetime spectroscopy (PALS). The effects of particle size and content on the methanol permeability, proton conductivity, swelling and FFV of the membranes are investigated. Compared to pure CS membrane, the hybrid membranes exhibit an increased proton conductivity to an acceptable level of 0.01 S cm -1 for DMFC application and a reduced methanol permeability of 5 × 10 -7 cm 2 s -1 at a 2 M methanol feed.

Zirconium tungstate/polymer nanocomposites: Challenges and opportunities

Energy Technology Data Exchange (ETDEWEB)

Lind, Cora; Kozy, Leah C. [Department of Chemistry, The University of Toledo, 2801W. Bancroft Street, Toledo, OH 43606 (United States); Coleman, Maria R.; Sharma, Gayathri R. [Department of Chemical Engineering, The University of Toledo, 2801W. Bancroft Street, Toledo, OH 43606 (United States)

2011-01-15

Negative thermal expansion (NTE) oxides are interesting materials for use in controlled thermal expansion composites. Cubic ZrW{sub 2}O{sub 8} is one of the most promising candidates due to its strong, isotropic NTE behaviour over a large temperature range. It is easily accessible from a hydrated precursor, ZrW{sub 2}O{sub 7}(OH){sub 2}. 2H{sub 2}O, which enables control of particle size and morphology during the topotactic conversion to the NTE phase. The preparation of high quality composites poses a number of challenges like compatibility of NTE material and composite matrix, stability of the NTE phase and particle morphology and size, which affect mixing and homogeneity. For ZrW{sub 2}O{sub 8}/polymer composites, surface modification is necessary to enhance interactions between the polymer matrix and the filler particles. In addition, small particle sizes are crucial to avoid settling of filler particles during polymer processing. This review presents results on the optimization of routes to nano-ZrW{sub 2}O{sub 8}, particle modification to achieve compatibility with polymers, preparation of NTE/polyimide composites and potential problems that can interfere with composite formation. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Dilute and Semidilute Solutions of a Nonionic, Rigid, Water-soluble Polymer

Science.gov (United States)

Russo, Paul; Huberty, Wayne; Zhang, Donghui; Water-Soluble Rodlike Polymer Team Collaboration

2014-03-01

The solution physics of random polymer chains was established largely on the behavior of commercial polymers such as polystyrene for organic solvents or nonionic poly(ethyleneoxide) for aqueous solvents. Not only are these materials widely available for industrial use, they can be synthesized to be essentially monodisperse. When it comes to stiff polymers, good choices are few and less prone to be used in industrial applications. Much was learned from polypeptides such as poly(benzylglutamate) or poly(stearylglutamate) in polar organic solvents and nonpolar organic solvents, respectively, but aqueous systems generally require charge. Poly(Nɛ-2-[2-(2-Methoxyethoxy) ethoxy]acetyl-L-Lysine) a.k.a. PEGL was pioneered by Deming and coworkers. In principle, PEGL provides a convenient platform from which to study stiff polymer behavior--phase relations, dynamics, liquid crystal formation and gelation--all with good molecular weight control and uniformity and without electrical charge. Still, a large gap in knowledge exists between PEGL and traditional rodlike polymer systems. To narrow this gap, dynamic and static scattering, circular dichroism, and viscosity measurements have been made in dilute and semidilute solutions as necessary preliminaries for lyotropic liquid crystalline and gel phases. Supported by NSF DMR 1306262. Department of Chemistry and Macromolecular Studies Group. Current address: Georgia Institute of Technology, School of Materials Science and Engineering.

Polymer Brushes: Synthesis, Characterization, Applications

Science.gov (United States)

Advincula, Rigoberto C.; Brittain, William J.; Caster, Kenneth C.; Rühe, Jürgen

2004-09-01

Materials scientists, polymer chemists, surface physicists and materials engineers will find this book a complete and detailed treatise on the field of polymer brushes, their synthesis, characterization and manifold applications. In a first section, the various synthetic pathways and different surface materials are introduced and explained, followed by a second section covering important aspects of characterization and analysis in both flat surfaces and particles. These specific surface initiated polymerization (SIP) systems such as linear polymers, homopolymers, block copolymers, and hyperbranched polymers are unique compared to previously reported systems by chemisorption or physisorption. They have found their way in both large-scale and miniature applications of polymer brushes, which is covered in the last section. Such 'hairy' surfaces offer fascinating opportunities for addressing numerous problems of both academic and, in particular, industrial interest: high-quality, functional or protective coatings, composite materials, surface engineered particles, metal-organic interfaces, biological applications, micro-patterning, colloids, nanoparticles, functional devices, and many more. It is the desire of the authors that this book will be of benefit to readers who want to "brush-up on polymers".

INVERSION SYMMETRY, ARCHITECTURE AND DISPERSITY, AND THEIR EFFECTS ON THERMODYNAMICS IN BULK AND CONFINED REGIONS: FROM RANDOMLY BRANCHED POLYMERS TO LINEAR CHAINS, STARS AND DENDRIMERS

Directory of Open Access Journals (Sweden)

P.D.Gujrati

2002-01-01

Full Text Available Theoretical evidence is presented in this review that architectural aspects can play an important role, not only in the bulk but also in confined geometries by using our recursive lattice theory, which is equally applicable to fixed architectures (regularly branched polymers, stars, dendrimers, brushes, linear chains, etc. and variable architectures, i.e. randomly branched structures. Linear chains possess an inversion symmetry (IS of a magnetic system (see text, whose presence or absence determines the bulk phase diagram. Fixed architectures possess the IS and yield a standard bulk phase diagram in which there exists a theta point at which two critical lines C and C' meet and the second virial coefficient A2 vanishes. The critical line C appears only for infinitely large polymers, and an order parameter is identified for this criticality. The critical line C' exists for polymers of all sizes and represents phase separation criticality. Variable architectures, which do not possess the IS, give rise to a topologically different phase diagram with no theta point in general. In confined regions next to surfaces, it is not the IS but branching and monodispersity, which becomes important in the surface regions. We show that branching plays no important role for polydisperse systems, but become important for monodisperse systems. Stars and linear chains behave differently near a surface.

Nanostructural and magnetic studies of virtually monodispersed NiFe2O4 nanocrystals synthesized by a liquid–solid-solution assisted hydrothermal route

International Nuclear Information System (INIS)

Li Xinghua; Tan Guoguo; Chen Wei; Zhou Baofan; Xue Desheng; Peng Yong; Li, Fashen; Mellors, Nigel J.

2012-01-01

This study presents a comprehensively and systematically structural, chemical and magnetic characterization of ∼9.5 nm virtually monodispersed nickel ferrite (NiFe 2 O 4 ) nanoparticles prepared using a modified liquid–solid-solution (LSS) assisted hydrothermal method. Lattice-resolution scanning transmission electron microscope (STEM) and converged beam electron diffraction pattern (CBED) techniques are adapted to characterize the detailed spatial morphology and crystal structure of individual NiFe 2 O 4 particles at nano scale for the first time. It is found that each NiFe 2 O 4 nanoparticle is single crystal with an fcc structure. The morphology investigation reveals that the prepared NiFe 2 O 4 nanoparticles of which the surfaces are decorated by oleic acid are dispersed individually in hexane. The chemical composition of nickel ferrite nanoparticles is measured to be 1:2 atomic ratio of Ni:Fe, indicating a pure NiFe 2 O 4 composition. Magnetic measurements reveal that the as-synthesized nanocrystals displayed superparamagnetic behavior at room temperature and were ferromagnetic at 10 K. The nanoscale characterization and magnetic investigation of monodispersed NiFe 2 O 4 nanoparticles should be significant for its potential applications in the field of biomedicine and magnetic fluid using them as magnetic materials.

Direct observation and analysis of yolk-shell materials using low-voltage high-resolution scanning electron microscopy: Nanometal-particles encapsulated in metal-oxide, carbon, and polymer

Energy Technology Data Exchange (ETDEWEB)

Asahina, Shunsuke; Suga, Mitsuo; Takahashi, Hideyuki [JEOL Ltd., SM Business Unit, Tokyo (Japan); Young Jeong, Hu [Graduate School of EEWS, WCU/BK21+, KAIST, Daejeon 305-701 (Korea, Republic of); Galeano, Carolina; Schüth, Ferdi [Department of Heterogeneous Catalysis, Max-Planck-Institut für Kohlenforschung, Mülheim (Germany); Terasaki, Osamu, E-mail: terasaki@mmk.su.se, E-mail: terasaki@kaist.ac.kr [Graduate School of EEWS, WCU/BK21+, KAIST, Daejeon 305-701 (Korea, Republic of); Department of Materials and Environmental Chemistry, Berzelii Centre EXSELENT on Porous Materials, Stockholm University, SE-10691 Stockholm (Sweden)

2014-11-01

Nanometal particles show characteristic features in chemical and physical properties depending on their sizes and shapes. For keeping and further enhancing their features, the particles should be protected from coalescence or degradation. One approach is to encapsulate the nanometal particles inside pores with chemically inert or functional materials, such as carbon, polymer, and metal oxides, which contain mesopores to allow permeation of only chemicals not the nanometal particles. Recently developed low-voltage high-resolution scanning electron microscopy was applied to the study of structural, chemical, and electron state of both nanometal particles and encapsulating materials in yolk-shell materials of Au@C, Ru/Pt@C, Au@TiO{sub 2}, and Pt@Polymer. Progresses in the following categories were shown for the yolk-shell materials: (i) resolution of topographic image contrast by secondary electrons, of atomic-number contrast by back-scattered electrons, and of elemental mapping by X-ray energy dispersive spectroscopy; (ii) sample preparation for observing internal structures; and (iii) X-ray spectroscopy such as soft X-ray emission spectroscopy. Transmission electron microscopy was also used for characterization of Au@C.

Artificial neural network based particle size prediction of polymeric nanoparticles.

Science.gov (United States)

Youshia, John; Ali, Mohamed Ehab; Lamprecht, Alf

2017-10-01

Particle size of nanoparticles and the respective polydispersity are key factors influencing their biopharmaceutical behavior in a large variety of therapeutic applications. Predicting these attributes would skip many preliminary studies usually required to optimize formulations. The aim was to build a mathematical model capable of predicting the particle size of polymeric nanoparticles produced by a pharmaceutical polymer of choice. Polymer properties controlling the particle size were identified as molecular weight, hydrophobicity and surface activity, and were quantified by measuring polymer viscosity, contact angle and interfacial tension, respectively. A model was built using artificial neural network including these properties as input with particle size and polydispersity index as output. The established model successfully predicted particle size of nanoparticles covering a range of 70-400nm prepared from other polymers. The percentage bias for particle prediction was 2%, 4% and 6%, for the training, validation and testing data, respectively. Polymer surface activity was found to have the highest impact on the particle size followed by viscosity and finally hydrophobicity. Results of this study successfully highlighted polymer properties affecting particle size and confirmed the usefulness of artificial neural networks in predicting the particle size and polydispersity of polymeric nanoparticles. Copyright © 2017 Elsevier B.V. All rights reserved.

Adsorption and flocculation by polymers and polymer mixtures.

Science.gov (United States)

Gregory, John; Barany, Sandor

2011-11-14

Polymers of various types are in widespread use as flocculants in several industries. In most cases, polymer adsorption is an essential prerequisite for flocculation and kinetic aspects are very important. The rates of polymer adsorption and of re-conformation (relaxation) of adsorbed chains are key factors that influence the performance of flocculants and their mode of action. Polyelectrolytes often tend to adopt a rather flat adsorbed configuration and in this state their action is mainly through charge effects, including 'electrostatic patch' attraction. When the relaxation rate is quite low, particle collisions may occur while the adsorbed chains are still in an extended state and flocculation by polymer bridging may occur. These effects are now well understood and supported by much experimental evidence. In recent years there has been considerable interest in the use of multi-component flocculants, especially dual-polymer systems. In the latter case, there can be significant advantages over the use of single polymers. Despite some complications, there is a broad understanding of the action of dual polymer systems. In many cases the sequence of addition of the polymers is important and the pre-adsorbed polymer can have two important effects: providing adsorption sites for the second polymer or causing a more extended adsorbed conformation as a result of 'site blocking'. Copyright © 2011 Elsevier B.V. All rights reserved.

Synthesis and Magnetic Properties of Nearly Monodisperse CoFe2O4Nanoparticles Through a Simple Hydrothermal Condition

Directory of Open Access Journals (Sweden)

Li Xing-Hua

2010-01-01

Full Text Available Abstract Nearly monodisperse cobalt ferrite (CoFe2O4 nanoparticles without any size-selection process have been prepared through an alluring method in an oleylamine/ethanol/water system. Well-defined nanospheres with an average size of 5.5 nm have been synthesized using metal chloride as the law materials and oleic amine as the capping agent, through a general liquid–solid-solution (LSS process. Magnetic measurement indicates that the particles exhibit a very high coercivity at 10 K and perform superparamagnetism at room temperature which is further illuminated by ZFC/FC curves. These superparamagnetic cobalt ferrite nanomaterials are considered to have potential application in the fields of biomedicine. The synthesis method is possible to be a general approach for the preparation of other pure binary and ternary compounds.

Deposition of Aerosol Particles in Electrically Charged Membrane Filters

Energy Technology Data Exchange (ETDEWEB)

Stroem, L

1972-05-15

A theory for the influence of electric charge on particle deposition on the surface of charged filters has been developed. It has been tested experimentally on ordinary membrane filters and Nuclepore filters of 8 mum pore size, with a bipolar monodisperse test aerosol of 1 mum particle diameter, and at a filter charge up to 20 muC/m2. Agreement with theory was obtained for the Coulomb force between filter and particle for both kinds of filters. The image force between charged filter and neutral particles did not result in the predicted deposition in the ordinary membrane filter, probably due to lacking correspondence between the filter model employed for the theory, and the real filter. For the Nuclepore filter a satisfactory agreement with theory was obtained, also at image interaction

Polymer architecture of magnetic gels: a review

Science.gov (United States)

Weeber, Rudolf; Hermes, Melissa; Schmidt, Annette M.; Holm, Christian

2018-02-01

In this review article, we provide an introduction to ferrogels, i.e. polymeric gels with embedded magnetic particles. Due to the interplay between magnetic and elastic properties of these materials, they are promising candidates for engineering and biomedical applications such as actuation and controlled drug release. Particular emphasis will be put on the polymer architecture of magnetic gels since it controls the degrees of freedom of the magnetic particles in the gel, and it is important for the particle-polymer coupling determining the mechanisms available for the gel deformation in magnetic fields. We report on the different polymer architectures that have been realized so far, and provide an overview of synthesis strategies and experimental techniques for the characterization of these materials. We further focus on theoretical and simulational studies carried out on magnetic gels, and highlight their contributions towards understanding the influence of the gels’ polymer architecture.

New nanocomposite surfaces and thermal interface materials based on mesoscopic microspheres, polymers and graphene flakes

Science.gov (United States)

Dmitriev, Alex A.; Dmitriev, Alex S.; Makarov, Petr; Mikhailova, Inna

2018-04-01

In recent years, there has been a great interest in the development and creation of new functional energy mate-rials, including for improving the energy efficiency of power equipment and for effectively removing heat from energy devices, microelectronics and optoelectronics (power micro electronics, supercapacitors, cooling of processors, servers and data centers). In this paper, the technology of obtaining new nanocomposites based on mesoscopic microspheres, polymers and graphene flakes is considered. The methods of sequential production of functional materials from graphene flakes of different volumetric concentration using epoxy polymers, as well as the addition of monodisperse microspheres are described. Data are given on the measurement of the contact angle and thermal conductivity of these nanocomposites with respect to the creation of thermal interface materials for cooling devices of electronics, optoelectronics and power engineering.

Phase stability and dynamics of entangled polymer-nanoparticle composites.

KAUST Repository

Mangal, Rahul

2015-06-05

Nanoparticle-polymer composites, or polymer-nanoparticle composites (PNCs), exhibit unusual mechanical and dynamical features when the particle size approaches the random coil dimensions of the host polymer. Here, we harness favourable enthalpic interactions between particle-tethered and free, host polymer chains to create model PNCs, in which spherical nanoparticles are uniformly dispersed in high molecular weight entangled polymers. Investigation of the mechanical properties of these model PNCs reveals that the nanoparticles have profound effects on the host polymer motions on all timescales. On short timescales, nanoparticles slow-down local dynamics of the host polymer segments and lower the glass transition temperature. On intermediate timescales, where polymer chain motion is typically constrained by entanglements with surrounding molecules, nanoparticles provide additional constraints, which lead to an early onset of entangled polymer dynamics. Finally, on long timescales, nanoparticles produce an apparent speeding up of relaxation of their polymer host.

Phase stability and dynamics of entangled polymer-nanoparticle composites.

KAUST Repository

Mangal, Rahul; Srivastava, Samanvaya; Archer, Lynden A

2015-01-01

Nanoparticle-polymer composites, or polymer-nanoparticle composites (PNCs), exhibit unusual mechanical and dynamical features when the particle size approaches the random coil dimensions of the host polymer. Here, we harness favourable enthalpic interactions between particle-tethered and free, host polymer chains to create model PNCs, in which spherical nanoparticles are uniformly dispersed in high molecular weight entangled polymers. Investigation of the mechanical properties of these model PNCs reveals that the nanoparticles have profound effects on the host polymer motions on all timescales. On short timescales, nanoparticles slow-down local dynamics of the host polymer segments and lower the glass transition temperature. On intermediate timescales, where polymer chain motion is typically constrained by entanglements with surrounding molecules, nanoparticles provide additional constraints, which lead to an early onset of entangled polymer dynamics. Finally, on long timescales, nanoparticles produce an apparent speeding up of relaxation of their polymer host.

Monodispersed macroporous architecture of nickel-oxide film as an anode material for thin-film lithium-ion batteries

International Nuclear Information System (INIS)

Wu, Mao-Sung; Lin, Ya-Ping

2011-01-01

A nickel-oxide film with monodispersed open macropores was prepared on a stainless-steel substrate by electrophoretic deposition of a polystyrene-sphere monolayer followed by anodic electrodeposition of nickel oxy-hydroxide. The deposited films convert to cubic nickel oxide after annealing at 400 o C for 1 h. Galvanostatic charge and discharge results indicate that the nickel-oxide film with monodispersed open macropores is capable of delivering a higher capacity than the bare nickel-oxide film, especially in high-rate charge and discharge processes. The lithiation capacity of macroporous nickel oxide reaches 1620 mA h g -1 at 1 C current discharge and decreases to 990 mA h g -1 at 15 C current discharge. The presence of monodispersed open macropores in the nickel-oxide film might facilitate the electrolyte penetration, diffusion, and migration. Electrochemical reactions between nickel oxide and lithium ions are therefore markedly improved by this tailored film architecture.

Ambiguity assessment of small-angle scattering curves from monodisperse systems.

Science.gov (United States)

Petoukhov, Maxim V; Svergun, Dmitri I

2015-05-01

A novel approach is presented for an a priori assessment of the ambiguity associated with spherically averaged single-particle scattering. The approach is of broad interest to the structural biology community, allowing the rapid and model-independent assessment of the inherent non-uniqueness of three-dimensional shape reconstruction from scattering experiments on solutions of biological macromolecules. One-dimensional scattering curves recorded from monodisperse systems are nowadays routinely utilized to generate low-resolution particle shapes, but the potential ambiguity of such reconstructions remains a major issue. At present, the (non)uniqueness can only be assessed by a posteriori comparison and averaging of repetitive Monte Carlo-based shape-determination runs. The new a priori ambiguity measure is based on the number of distinct shape categories compatible with a given data set. For this purpose, a comprehensive library of over 14,000 shape topologies has been generated containing up to seven beads closely packed on a hexagonal grid. The computed scattering curves rescaled to keep only the shape topology rather than the overall size information provide a `scattering map' of this set of shapes. For a given scattering data set, one rapidly obtains the number of neighbours in the map and the associated shape topologies such that in addition to providing a quantitative ambiguity measure the algorithm may also serve as an alternative shape-analysis tool. The approach has been validated in model calculations on geometrical bodies and its usefulness is further demonstrated on a number of experimental X-ray scattering data sets from proteins in solution. A quantitative ambiguity score (a-score) is introduced to provide immediate and convenient guidance to the user on the uniqueness of the ab initio shape reconstruction from the given data set.

Intrinsic immunogenicity of rapidly-degradable polymers evolves during degradation.

Science.gov (United States)

Andorko, James I; Hess, Krystina L; Pineault, Kevin G; Jewell, Christopher M

2016-03-01

Recent studies reveal many biomaterial vaccine carriers are able to activate immunostimulatory pathways, even in the absence of other immune signals. How the changing properties of polymers during biodegradation impact this intrinsic immunogenicity is not well studied, yet this information could contribute to rational design of degradable vaccine carriers that help direct immune response. We use degradable poly(beta-amino esters) (PBAEs) to explore intrinsic immunogenicity as a function of the degree of polymer degradation and polymer form (e.g., soluble, particles). PBAE particles condensed by electrostatic interaction to mimic a common vaccine approach strongly activate dendritic cells, drive antigen presentation, and enhance T cell proliferation in the presence of antigen. Polymer molecular weight strongly influences these effects, with maximum stimulation at short degradation times--corresponding to high molecular weight--and waning levels as degradation continues. In contrast, free polymer is immunologically inert. In mice, PBAE particles increase the numbers and activation state of cells in lymph nodes. Mechanistic studies reveal that this evolving immunogenicity occurs as the physicochemical properties and concentration of particles change during polymer degradation. This work confirms the immunological profile of degradable, synthetic polymers can evolve over time and creates an opportunity to leverage this feature in new vaccines. Degradable polymers are increasingly important in vaccination, but how the inherent immunogenicity of polymers changes during degradation is poorly understood. Using common rapidly-degradable vaccine carriers, we show that the activation of immune cells--even in the absence of other adjuvants--depends on polymer form (e.g., free, particulate) and the extent of degradation. These changing characteristics alter the physicochemical properties (e.g., charge, size, molecular weight) of polymer particles, driving changes in

Quasi-two-dimensional complex plasma containing spherical particles and their binary agglomerates.

Science.gov (United States)

Chaudhuri, M; Semenov, I; Nosenko, V; Thomas, H M

2016-05-01

A unique type of quasi-two-dimensional complex plasma system was observed which consisted of monodisperse microspheres and their binary agglomerations (dimers). The particles and their dimers levitated in a plasma sheath at slightly different heights and formed two distinct sublayers. The system did not crystallize and may be characterized as a disordered solid. The dimers were identified based on their characteristic appearance in defocused images, i.e., rotating interference fringe patterns. The in-plane and interplane particle separations exhibit nonmonotonic dependence on the discharge pressure.

A Study of Functional Polymer Colloids Prepared Using Thiol-Ene/Yne Click Chemistry

Science.gov (United States)

Durham, Olivia Z.

This project demonstrates the first instance of thiol-ene chemistry as the polymerization method for the production of polymer colloids in two-phase heterogeneous suspensions, miniemulsions, and emulsions. This work was also expanded to thiol-yne chemistry for the production of polymer particles containing increased crosslinking density. The utility of thiol-ene and thiol-yne chemistries for polymerization and polymer modification is well established in bulk systems. These reactions are considered 'click' reactions, which can be defined as processes that are both facile and simple, offering high yields with nearly 100% conversion, no side products, easy product separation, compatibility with a diverse variety of commercially available starting materials, and orthogonality with other chemistries. In addition, thiol-ene and thiol-yne chemistry follow a step-growth mechanism for the development of highly uniform polymer networks, where polymer growth is dependent on the coupling of functional groups. These step-growth polymerization systems are in stark contrast to the chain-growth mechanisms of acrylic and styrenic monomers that have dominated the field of conventional heterogeneous polymerizations. Preliminary studies evaluated the mechanism of particle production in suspension and miniemulsion systems. Monomer droplets were compared to the final polymer particles to confirm that particle growth occurred through the polymerization of monomer droplets. Additional parameters examined include homogenization energy (mechanical mixing), diluent species and concentration, and monomer content. These reactions were conducted using photoinitiation to yield particles in a matter of minutes with diameters in the size range of several microns to hundreds of microns in suspensions or submicron particles in miniemulsions. Improved control over the particle size and size distribution was examined through variation of reaction parameters. In addition, a method of seeded suspension

Electrochemistry of conductive polymers 39. Contacts between conducting polymers and noble metal nanoparticles studied by current-sensing atomic force microscopy.

Science.gov (United States)

Cho, Shin Hyo; Park, Su-Moon

2006-12-28

Electrical properties of contacts formed between conducting polymers and noble metal nanoparticles have been examined using current-sensing atomic force microscopy (CS-AFM). Contacts formed between electrochemically prepared pi-conjugated polymer films such as polypyrrole (PPy), poly(3-methylthiophene) (P3MeT), as well as poly(3,4-ethylenedioxythiophene) (PEDOT) and noble metal nanoparticles including platinum (Pt), gold (Au), and silver (Ag) have been examined. The Pt nanoparticles were electrochemically deposited on a pre-coated PPy film surface by reducing a platinum precursor (PtCl62-) at a constant potential. Both current and scanning electron microscopic images of the film showed the presence of Pt islands. The Au and Ag nanoparticles were dispersed on the P3MeT and PEDOT film surfaces simply by dipping the polymer films into colloid solutions containing Au or Ag particles for specified periods (5 to approximately 10 min). The deposition of Au or Ag particles resulted from either their physical adsorption or chemical bonding between particles and the polymer surface depending on the polymer. When compared with PPy, P3MeT and PEDOT showed a stronger binding to Au or Ag nanoparticles when dipped in their colloidal solutions for the same period. This indicates that Au and Ag particles are predominantly linked with the sulfur atoms via chemical bonding. Of the two, PEDOT was more conductive at the sites where the particles are connected to the polymer. It appears that PEDOT has better aligned sulfur atoms on the surface and is strongly bonded to Au and Ag nanoparticles due to their strong affinity to gold and silver. The current-voltage curves obtained at the metal islands demonstrate that the contacts between these metal islands and polymers are ohmic.

Clinically Relevant Anticancer Polymer Paclitaxel Therapeutics

Directory of Open Access Journals (Sweden)

Danbo Yang

2010-12-01

Full Text Available The concept of utilizing polymers in drug delivery has been extensively explored for improving the therapeutic index of small molecule drugs. In general, polymers can be used as polymer-drug conjugates or polymeric micelles. Each unique application mandates its own chemistry and controlled release of active drugs. Each polymer exhibits its own intrinsic issues providing the advantage of flexibility. However, none have as yet been approved by the U.S. Food and Drug Administration. General aspects of polymer and nano-particle therapeutics have been reviewed. Here we focus this review on specific clinically relevant anticancer polymer paclitaxel therapeutics. We emphasize their chemistry and formulation, in vitro activity on some human cancer cell lines, plasma pharmacokinetics and tumor accumulation, in vivo efficacy, and clinical outcomes. Furthermore, we include a short review of our recent developments of a novel poly(L-g-glutamylglutamine-paclitaxel nano-conjugate (PGG-PTX. PGG-PTX has its own unique property of forming nano-particles. It has also been shown to possess a favorable profile of pharmacokinetics and to exhibit efficacious potency. This review might shed light on designing new and better polymer paclitaxel therapeutics for potential anticancer applications in the clinic.

Clinically Relevant Anticancer Polymer Paclitaxel Therapeutics

International Nuclear Information System (INIS)

Yang, Danbo; Yu, Lei; Van, Sang

2010-01-01

The concept of utilizing polymers in drug delivery has been extensively explored for improving the therapeutic index of small molecule drugs. In general, polymers can be used as polymer-drug conjugates or polymeric micelles. Each unique application mandates its own chemistry and controlled release of active drugs. Each polymer exhibits its own intrinsic issues providing the advantage of flexibility. However, none have as yet been approved by the U.S. Food and Drug Administration. General aspects of polymer and nano-particle therapeutics have been reviewed. Here we focus this review on specific clinically relevant anticancer polymer paclitaxel therapeutics. We emphasize their chemistry and formulation, in vitro activity on some human cancer cell lines, plasma pharmacokinetics and tumor accumulation, in vivo efficacy, and clinical outcomes. Furthermore, we include a short review of our recent developments of a novel poly(l-γ-glutamylglutamine)-paclitaxel nano-conjugate (PGG-PTX). PGG-PTX has its own unique property of forming nano-particles. It has also been shown to possess a favorable profile of pharmacokinetics and to exhibit efficacious potency. This review might shed light on designing new and better polymer paclitaxel therapeutics for potential anticancer applications in the clinic

Clinically Relevant Anticancer Polymer Paclitaxel Therapeutics

Energy Technology Data Exchange (ETDEWEB)

Yang, Danbo [Biomedical Engineering and Technology Institute, Institutes for Advanced Interdisciplinary Research, East China Normal University, 3663 North Zhongshan Road, Shanghai, 200062 (China); Yu, Lei, E-mail: yu-lei@gg.nitto.co.jp [Biomedical Engineering and Technology Institute, Institutes for Advanced Interdisciplinary Research, East China Normal University, 3663 North Zhongshan Road, Shanghai, 200062 (China); Biomedical Group, Nitto Denko Technical Corporation, 501 Via Del Monte, Oceanside, CA 92058 (United States); Van, Sang [Biomedical Group, Nitto Denko Technical Corporation, 501 Via Del Monte, Oceanside, CA 92058 (United States)

2010-12-23

The concept of utilizing polymers in drug delivery has been extensively explored for improving the therapeutic index of small molecule drugs. In general, polymers can be used as polymer-drug conjugates or polymeric micelles. Each unique application mandates its own chemistry and controlled release of active drugs. Each polymer exhibits its own intrinsic issues providing the advantage of flexibility. However, none have as yet been approved by the U.S. Food and Drug Administration. General aspects of polymer and nano-particle therapeutics have been reviewed. Here we focus this review on specific clinically relevant anticancer polymer paclitaxel therapeutics. We emphasize their chemistry and formulation, in vitro activity on some human cancer cell lines, plasma pharmacokinetics and tumor accumulation, in vivo efficacy, and clinical outcomes. Furthermore, we include a short review of our recent developments of a novel poly(l-γ-glutamylglutamine)-paclitaxel nano-conjugate (PGG-PTX). PGG-PTX has its own unique property of forming nano-particles. It has also been shown to possess a favorable profile of pharmacokinetics and to exhibit efficacious potency. This review might shed light on designing new and better polymer paclitaxel therapeutics for potential anticancer applications in the clinic.

Self-healing of polymer modified concrete

Directory of Open Access Journals (Sweden)

Abd_Elmoaty M. Abd_Elmoaty

2011-06-01

Full Text Available Self healing phenomenon of concrete has been observed in traditional, fibrous, self compacting concrete. This phenomenon occurred mainly due to the presence of unhydrated cement particles in the presence of water. Mechanism of polymer in concrete depends on creating a layer and net of polymer around cement particles which enhances the properties of polymer modified concrete. This mechanism may affect the self healing of this type of concrete. This work aims to study the presence of the self healing phenomenon in polymer modified concrete and the related parameters. An experimental investigation on self healing of polymer modified concrete was undertaken. In this research work, effect of polymer type, polymer dose, cement content, cement type, w/cm ratio and age of damage were studied. The healing process extended up to 60 days. Ultrasonic pulse velocity measurements were used to evaluate the healing process. Results indicated that, the self healing phenomenon existed in polymer modified concrete as in traditional concrete. The increase of polymer dose increases the healing degree at the same healing time. This increase depends on polymer type. Also, the decrease of w/cm ratio reduces the self healing degree while the use of Type V Portland cement improves the self healing process compared with Type I Portland cement. Cement content has an insignificant effect on healing process for both concrete with and without polymer. In addition, the increase of damage age decreases the efficiency of self healing process.

Direct observation and analysis of york-shell materials using low-voltage high-resolution scanning electron microscopy: Nanometal-particles encapsulated in metal-oxide, carbon, and polymer

Directory of Open Access Journals (Sweden)

Shunsuke Asahina

2014-11-01

Full Text Available Nanometal particles show characteristic features in chemical and physical properties depending on their sizes and shapes. For keeping and further enhancing their features, the particles should be protected from coalescence or degradation. One approach is to encapsulate the nanometal particles inside pores with chemically inert or functional materials, such as carbon, polymer, and metal oxides, which contain mesopores to allow permeation of only chemicals not the nanometal particles. Recently developed low-voltage high-resolution scanning electron microscopy was applied to the study of structural, chemical, and electron state of both nanometal particles and encapsulating materials in york-shell materials of Au@C, Ru/Pt@C, Au@TiO2, and Pt@Polymer. Progresses in the following categories were shown for the york-shell materials: (i resolution of topographic image contrast by secondary electrons, of atomic-number contrast by back-scattered electrons, and of elemental mapping by X-ray energy dispersive spectroscopy; (ii sample preparation for observing internal structures; and (iii X-ray spectroscopy such as soft X-ray emission spectroscopy. Transmission electron microscopy was also used for characterization of Au@C.

A ''quick DYECET'' method for ECE particle tracks in polymer detectors

International Nuclear Information System (INIS)

Sohrabi, M.; Mahdi, S.

1993-01-01

The new dyed electrochemically etched track (DEYCET) method recently developed at the National Radiation Protection Department (NRPD) of the Atomic Energy Organization of Iran (AEOI) using sensitization and dyeing steps is a useful and powerful method for dyeing charged particle and neutron-induced-recoil tracks in polymer detectors. This original DYECET method is effective but time consuming due to the steps for sensitization and dyeing which usually takes several hours. A ''Quick DYECET'' method, also recently developed in our laboratory, is introduced in this paper which dyes ECE tracks effectively in different colours within a few minutes. This new method can dye ECE tracks, cracks, fractures and fractals with different water and/or alcohol soluble dyes using cold or hot dyebaths. The method provides a high contrast and a high resolution of ECE tracks for visual track counting especially at high track densities. Some preliminary results are reported and discussed. (author)

Multi-scale entropic depletion phenomena in polymer liquids

Energy Technology Data Exchange (ETDEWEB)

Banerjee, Debapriya [Department of Materials Science, University of Illinois, Urbana, Illinois 61801 (United States); Schweizer, Kenneth S., E-mail: kschweiz@illinois.edu [Department of Materials Science, University of Illinois, Urbana, Illinois 61801 (United States); Department of Chemistry, University of Illinois, Urbana, Illinois 61801 (United States); Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801 (United States)

2015-06-07

We apply numerical polymer integral equation theory to study the entropic depletion problem for hard spheres dissolved in flexible chain polymer melts and concentrated solutions over an exceptionally wide range of polymer radius of gyration to particle diameter ratios (R{sub g}/D), particle-monomer diameter ratios (D/d), and chain lengths (N) including the monomer and oligomer regimes. Calculations are performed based on a calibration of the effective melt packing fraction that reproduces the isobaric dimensionless isothermal compressibility of real polymer liquids. Three regimes of the polymer-mediated interparticle potential of mean force (PMF) are identified and analyzed in depth. (i) The magnitude of the contact attraction that dominates thermodynamic stability scales linearly with D/d and exhibits a monotonic and nonperturbative logarithmic increase with N ultimately saturating in the long chain limit. (ii) A close to contact repulsive barrier emerges that grows linearly with D/d and can attain values far in excess of thermal energy for experimentally relevant particle sizes and chain lengths. This raises the possibility of kinetic stabilization of particles in nanocomposites. The barrier grows initially logarithmically with N, attains a maximum when 2R{sub g} ∼ D/2, and then decreases towards its asymptotic long chain limit as 2R{sub g} ≫ D. (iii) A long range (of order R{sub g}) repulsive, exponentially decaying component of the depletion potential emerges when polymer coils are smaller than, or of order, the nanoparticle diameter. Its amplitude is effectively constant for 2R{sub g} ≤ D. As the polymer becomes larger than the particle, the amplitude of this feature decreases extremely rapidly and becomes negligible. A weak long range and N-dependent component of the monomer-particle pair correlation function is found which is suggested to be the origin of the long range repulsive PMF. Implications of our results for thermodynamics and miscibility are

Influences of Electrolytes on the Soap-free Emulsion Copolymerization of St-MMA-AA

Institute of Scientific and Technical Information of China (English)

Rong Long LI; Cheng You KAN; Yi DU; Ze Ping LI

2006-01-01

Monodisperse functional polymer microspheres with different particle size and with clean surface were prepared by batch soap-free emulsion polymerization of styrene, methyl methacrylate and acrylic acid in the presence of salts, and the influences of type and amount of electrolytes on polymerization process and particle morphology were investigated. Results showed that there was a critical concentration for different electrolyte to make polymerization process and the resultant emulsion stable, and the particle size increased with the increase of electrolyte concentration. The effect of metal ions was Ca2+＞＞K+＞Na+＞Li+, and the effect of haloids was Br-＞Cl-＞F-.

Solvent-free formation of hydroxyapatite coated biodegradable particles via nanoparticle-stabilized emulsion route

International Nuclear Information System (INIS)

Okada, Masahiro; Fujii, Syuji; Nishimura, Taiki; Nakamura, Yoshinobu; Takeda, Shoji; Furuzono, Tsutomu

2012-01-01

Highlights: ► Hydroxyapatite (HAp) nanoparticles stabilized polymer melt-in-water emulsions without any molecular surfactants. ► Interaction between polymer and HAp played a crucial role. ► HAp-coated polymer particles were obtained from the emulsions without any organic solvents. - Abstract: Hydroxyapatite (HAp) nanoparticle-coated biodegradable polymer particles were fabricated from a nanoparticle-stabilized emulsion in the absence of any molecular surfactants or organic solvents. First, a polymer melt-in-water emulsion was prepared by mixing a water phase containing nanosized HAp particles as a particulate emulsifier and an oil phase consisting of poly(ε-caprolactone) (PCL) or poly(L-lactide-co-ε-caprolactone) (P(LLA-CL)) above its melting point. It was clarified that the interaction between ester/carboxyl groups of the polymers and the HAp nanoparticles at the polymer–water interface played a crucial role to prepare the nanoparticle-stabilized emulsion. The HAp nanoparticle-coated biodegradable polymer particle (a polymer solid-in-water emulsion) was fabricated by cooling the emulsion. The particle morphology and particle size were evaluated using scanning electron microscope.

Improved polymer nanocomposite dielectric breakdown performance through barium titanate to epoxy interface control

Energy Technology Data Exchange (ETDEWEB)

Siddabattuni, Sasidhar [Missouri University of Science and Technology (formerly the University of Missouri-Rolla), Chemistry Department, 400W. 11th Street, Rolla, MO 65409 (United States); Schuman, Thomas P., E-mail: tschuman@mst.edu [Missouri University of Science and Technology (formerly the University of Missouri-Rolla), Chemistry Department, 400W. 11th Street, Rolla, MO 65409 (United States); Dogan, Fatih [Missouri University of Science and Technology, Materials Science and Engineering Department, 1400N. Bishop Avenue, Rolla, MO 65409 (United States)

2011-11-15

Highlights: > A covalent filler-matrix interface improves the dielectric properties of a polymer-particle nanocomposite dielectric. > A covalent interface reduced the polymer free volume around the nanoparticles as assessed through T{sub g} measurements. > Composite T{sub g} was raised and breakdown strength improved for nanocomposites with a covalent polymer-particle interface. > A larger Maxwell-Wagner (MW) relaxation correlated with reduced breakdown strengths and energy storage densities. > The MW relaxation could be considered a dielectric defect regarding breakdown strength and energy storage density. - Abstract: A composite approach to dielectric design has the potential to provide improved permittivity as well as high breakdown strength and thus afford greater electrical energy storage density. Interfacial coupling is an effective approach to improve the polymer-particle composite dielectric film resistance to charge flow and dielectric breakdown. A bi-functional interfacial coupling agent added to the inorganic oxide particles' surface assists dispersion into the thermosetting epoxy polymer matrix and upon composite cure reacts covalently with the polymer matrix. The composite then retains the glass transition temperature of pure polymer, provides a reduced Maxwell-Wagner relaxation of the polymer-particle composite, and attains a reduced sensitivity to dielectric breakdown compared to particle epoxy composites that lack interfacial coupling between the composite filler and polymer matrix. Besides an improved permittivity, the breakdown strength and thus energy density of a covalent interface nanoparticle barium titanate in epoxy composite dielectric film, at a 5 vol.% particle concentration, was significantly improved compared to a pure polymer dielectric film. The interfacially bonded, dielectric composite film had a permittivity {approx}6.3 and at a 30 {mu}m thickness achieved a calculated energy density of 4.6 J/cm{sup 3}.

Improved polymer nanocomposite dielectric breakdown performance through barium titanate to epoxy interface control

International Nuclear Information System (INIS)

Siddabattuni, Sasidhar; Schuman, Thomas P.; Dogan, Fatih

2011-01-01

Highlights: → A covalent filler-matrix interface improves the dielectric properties of a polymer-particle nanocomposite dielectric. → A covalent interface reduced the polymer free volume around the nanoparticles as assessed through T g measurements. → Composite T g was raised and breakdown strength improved for nanocomposites with a covalent polymer-particle interface. → A larger Maxwell-Wagner (MW) relaxation correlated with reduced breakdown strengths and energy storage densities. → The MW relaxation could be considered a dielectric defect regarding breakdown strength and energy storage density. - Abstract: A composite approach to dielectric design has the potential to provide improved permittivity as well as high breakdown strength and thus afford greater electrical energy storage density. Interfacial coupling is an effective approach to improve the polymer-particle composite dielectric film resistance to charge flow and dielectric breakdown. A bi-functional interfacial coupling agent added to the inorganic oxide particles' surface assists dispersion into the thermosetting epoxy polymer matrix and upon composite cure reacts covalently with the polymer matrix. The composite then retains the glass transition temperature of pure polymer, provides a reduced Maxwell-Wagner relaxation of the polymer-particle composite, and attains a reduced sensitivity to dielectric breakdown compared to particle epoxy composites that lack interfacial coupling between the composite filler and polymer matrix. Besides an improved permittivity, the breakdown strength and thus energy density of a covalent interface nanoparticle barium titanate in epoxy composite dielectric film, at a 5 vol.% particle concentration, was significantly improved compared to a pure polymer dielectric film. The interfacially bonded, dielectric composite film had a permittivity ∼6.3 and at a 30 μm thickness achieved a calculated energy density of 4.6 J/cm 3 .

Nano- and Micro-sized Molecularly Imprinted Polymer Particles on Solid Surfaces

OpenAIRE

Kamra, Tripta

2015-01-01

Molecularly imprinted polymers (MIPs) are artificial receptors made by imprinting template molecules in a polymer matrix followed by their removal through washing to obtain a specific and selective template cavities. This property of the MIPs have made them a very efficient material for diverse applications such as chromatography, purification, drug sensing, etc. Recently, zero-dimensional polymer materials, in the present case molecularly imprinted polymer nanoparticles (MIP nanoparticles), ...

Emulsion Polymerization of Etyl Acrylate: The Effect of Surfactant, Initiator Concentration and PolymerizationTechnique on Particle Size Distribution

OpenAIRE

Nitri Arinda; Emil Budianto; Helmiyati

2009-01-01

Emulsion polymerization was conducted using ethyl acrylate monomer. Theeffect of sodium lauryl sulfate concentration, ammonium persulfate concentration, the various of polymerizationtechniques and feeding time to the conversion, particle size and its distribution were observed. The purpose of thisresearch is to obtain the optimum condition of ethyl acrylate homopolymer with particle size around 100 nm, to get theparticle size distribution monodisperse and to get solid content value of the exp...

Polymer Directed Protein Assemblies

Directory of Open Access Journals (Sweden)

Patrick van Rijn

2013-05-01

Full Text Available Protein aggregation and protein self-assembly is an important occurrence in natural systems, and is in some form or other dictated by biopolymers. Very obvious influences of biopolymers on protein assemblies are, e.g., virus particles. Viruses are a multi-protein assembly of which the morphology is dictated by poly-nucleotides namely RNA or DNA. This “biopolymer” directs the proteins and imposes limitations on the structure like the length or diameter of the particle. Not only do these bionanoparticles use polymer-directed self-assembly, also processes like amyloid formation are in a way a result of directed protein assembly by partial unfolded/misfolded biopolymers namely, polypeptides. The combination of proteins and synthetic polymers, inspired by the natural processes, are therefore regarded as a highly promising area of research. Directed protein assembly is versatile with respect to the possible interactions which brings together the protein and polymer, e.g., electrostatic, v.d. Waals forces or covalent conjugation, and possible combinations are numerous due to the large amounts of different polymers and proteins available. The protein-polymer interacting behavior and overall morphology is envisioned to aid in clarifying protein-protein interactions and are thought to entail some interesting new functions and properties which will ultimately lead to novel bio-hybrid materials.

Novel preparation of monodisperse poly(styrene-co-divinylbenzene) microspheres by controlled dispersion polymerization

Czech Academy of Sciences Publication Activity Database

Šálek, Petr; Horák, Daniel; Hromádková, Jiřina

2018-01-01

Roč. 60, č. 1 (2018), s. 9-15 ISSN 1560-0904 R&D Projects: GA MŠk(CZ) LQ1604; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61389013 Keywords : sized polystyrene particles * cross-linking * copolymerization Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 0.621, year: 2016 https://link.springer.com/article/10.1134/S1560090418010116

Dosimetry of 239Pu in dogs that inhaled monodisperse aerosols of 239PuO2

International Nuclear Information System (INIS)

Guilmette, R.A.; Muggenburg, B.A.; Hahn, F.F.; Mewhinney, J.A.; Seiler, F.A.; Boecker, B.B.; McClellan, R.O.

1987-01-01

Existing data from human exposure cases and experimental animal studies on the fate and dosimetry of inhaled insoluble Pu particles are inadequate to provide a comprehensive description and evaluation of the tissues at risk from the alpha radiations of Pu. To improve our knowledge of the dosimetry of inhaled insoluble 239 PuO 2 , this paper describes the uptake and retention of 239 Pu in the tissues of dogs that received single inhalation exposures to monodisperse aerosols of 239 PuO 2 . These data include times through 3 years after exposure. Using analytical functions fitted to each tissue data set, 1100-day radiation doses were calculated for lung, liver, skeleton, kidney, spleen, and tracheobronchial, mediastinal, sternal, hepatic, mandibular, and retropharyngeal lymph nodes. The dosimetry results suggest that the lung and lymph nodes associated with lymphatic drainage of the respiratory tract are the principal sites of alpha irradiation. However, the doses for the different respiratory tract lymph nodes vary by a factor of 2000, suggesting that assuming equivalent doses to respiratory tract lymph nodes is not appropriate. Other tissues receive radiation doses also but at levels one to three orders of magnitude less than the lung. Particle size dependence on uptake and retention was noted for the skeleton, mediastinal lymph nodes, hepatic lymph nodes, retropharyngeal lymph nodes, and mandibular lymph nodes

Particle beam experiments for the analysis of reactive sputtering processes in metals and polymer surfaces

Energy Technology Data Exchange (ETDEWEB)

Corbella, Carles; Grosse-Kreul, Simon; Kreiter, Oliver; Arcos, Teresa de los; Benedikt, Jan; Keudell, Achim von [RD Plasmas with Complex Interactions, Ruhr-Universität Bochum, Universitätsstr. 150, 44780 Bochum (Germany)

2013-10-15

A beam experiment is presented to study heterogeneous reactions relevant to plasma-surface interactions in reactive sputtering applications. Atom and ion sources are focused onto the sample to expose it to quantified beams of oxygen, nitrogen, hydrogen, noble gas ions, and metal vapor. The heterogeneous surface processes are monitored in situ by means of a quartz crystal microbalance and Fourier transform infrared spectroscopy. Two examples illustrate the capabilities of the particle beam setup: oxidation and nitriding of aluminum as a model of target poisoning during reactive magnetron sputtering, and plasma pre-treatment of polymers (PET, PP)

Bis-polymer lipid-peptide conjugates and nanoparticles thereof

Energy Technology Data Exchange (ETDEWEB)

Xu, Ting; Dong, He; Shu, Jessica; Dube, Nikhil

2018-04-24

The present invention provides bis-polymer lipid-peptide conjugates containing a hydrophobic block and headgroup containing a helical peptide and two polymer blocks. The conjugates can self-assemble to form helix bundle subunits, which in turn assemble to provide micellar nanocarriers for drug cargos and other agents. Particles containing the conjugates and methods for forming the particles are also disclosed.

Monodispersepoly[BMA-co-(COPS-I)] Particles by Soap-Free Emulsion Copolymerization and Its Optical Properties as Photonic Crystals.

Science.gov (United States)

Lee, Ki Chang; Choo, Hun Seung

2015-10-01

In order to study the surfactant-free emulsion copolymerization of benzyl methacrylate (BMA) with sodium 1-allyloxy-2-hydroxypropane sulfonate (COPS-I) and the resulting optical properties, a series of experiments was carried out at various reaction conditions such as the changes of BMA concentration, COPS-I concentration, BMA concentration under a fixed COPS-I amount, initiator and divinyl benzene (DVB) concentration. All the latices showed highly monodispersed spherical particles in the size range of 144~435 nm and the respective shiny structural colors from their colloidal photonic crystals. It is found that the changes in such polymerization factors greatly affect the number of particles and particle diameter, polymerization rate, molecular weight, zeta-potential, and refractive indices. The increase of number of particles led to the increased rate of polymerization and zeta-potential of the latices, on the other hand, to the decreased molecular weight. Refractive indices and the reflectivity increased with COPS-I concentration, on the other hand, and decreased with DVB concentration. Especially, refractive indices of the resulting poly[BMA-co-(COPS-I)] colloidal photonic crystals showed much higher values of 1.65~2.21 than that of polystyrene, due to the formation of core-shell shaped morphology. Monodisperse and high refractive index of poly[BMA-co-(COPS-I)] particles prepared in this work could be used for the study in photonic crystals and electrophoretic display.

Making PMMA, PMA, PVAc and PSt nano particles using radiation

International Nuclear Information System (INIS)

Hidi, P.; Napper, D.H.; Sangster, D.F.

2000-01-01

Full text: During the last decade considerable research effort has been directed to making very small (10-50 nm diam.) nano size polymer particles. Most of the techniques described used more than one surfactant at high concentrations and resulted in relatively low polymer concentration. We have developed methods to make nano size polymer particles from methyl methacrylate (MMA), methyl acrylate (MA), vinyl acetat (Vac) and styrene (St) with a single anionic surfactant and gamma radiation. We succeeded in making nano particles in up to 15% concentration and with much higher polymer/ surfactant ratio than the earlier methods. With the radiation technique we can obtain high yield of polymer and can control the particle size of the polymer in the 2 S 2 0 8 ) instead of gamma irradiation. At present we prefer gamma initiation, because we have much better control and reproducibility of the exothermic polymerisation reaction, hence the critical parameters can be evaluated more accurately. We have started to use the different nano particles prepared for adsorption studies, as seeds for polymerisation and for making transparent gels with nano structure. We are also looking for other applications of the nano particles. It should be noted that the surface area of 1 gram of 20 nm diameter spheres is 300m 2

Surface functionalized hollow silica particles and composites

KAUST Repository

Rodionov, Valentin

2017-05-26

Composition comprising hollow spherical silica particles having outside particle walls and inside particle walls, wherein the particles have an average particle size of about 10 nm to about 500 nm and an average wall thickness of about 10 nm to about 50 nm; and wherein the particles are functionalized with at least one organic functional group on the outside particle wall, on the inside particle wall, or on both the outside and inside particle walls, wherein the organic functional group is in a reacted or unreacted form. The organic functional group can be epoxy. The particles can be mixed with polymer precursor or a polymer material such as epoxy to form a prepreg or a nanocomposite. Lightweight but strong materials can be formed. Low loadings of hollow particles can be used.

Surface functionalized hollow silica particles and composites

KAUST Repository

Rodionov, Valentin; Khanh, Vu Bao

2017-01-01

Composition comprising hollow spherical silica particles having outside particle walls and inside particle walls, wherein the particles have an average particle size of about 10 nm to about 500 nm and an average wall thickness of about 10 nm to about 50 nm; and wherein the particles are functionalized with at least one organic functional group on the outside particle wall, on the inside particle wall, or on both the outside and inside particle walls, wherein the organic functional group is in a reacted or unreacted form. The organic functional group can be epoxy. The particles can be mixed with polymer precursor or a polymer material such as epoxy to form a prepreg or a nanocomposite. Lightweight but strong materials can be formed. Low loadings of hollow particles can be used.

Design of monodisperse and well-defined polypeptide-based polyvalent inhibitors of anthrax toxin.

Science.gov (United States)

Patke, Sanket; Boggara, Mohan; Maheshwari, Ronak; Srivastava, Sunit K; Arha, Manish; Douaisi, Marc; Martin, Jacob T; Harvey, Ian B; Brier, Matthew; Rosen, Tania; Mogridge, Jeremy; Kane, Ravi S

2014-07-28

The design of polyvalent molecules, presenting multiple copies of a specific ligand, represents a promising strategy to inhibit pathogens and toxins. The ability to control independently the valency and the spacing between ligands would be valuable for elucidating structure-activity relationships and for designing potent polyvalent molecules. To that end, we designed monodisperse polypeptide-based polyvalent inhibitors of anthrax toxin in which multiple copies of an inhibitory toxin-binding peptide were separated by flexible peptide linkers. By tuning the valency and linker length, we designed polyvalent inhibitors that were over four orders of magnitude more potent than the corresponding monovalent ligands. This strategy for the rational design of monodisperse polyvalent molecules may not only be broadly applicable for the inhibition of toxins and pathogens, but also for controlling the nanoscale organization of cellular receptors to regulate signaling and the fate of stem cells. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nonlinear Stress Relaxation of ``Quasi-monodisperse'' Miscible Blends of cis-Polyisoprene and Poly(ptert-butylstyrene)

Science.gov (United States)

Watanabe, Hiroshi; Matsumiya, Yumi

Viscoelastic relaxation was examined for entangled miscible blends of cis-polyisoprene (PI) and poly(ptert-butylstyrene) (PtBS). The terminal relaxation times of PI and PtBS therein, τPI and τPtBS, changed with the composition wPI and the molecular weights MPI and MPtBS. This ratio became unity when the wPI, MPI, and MPtBS values were chosen adequately. For example, in a blend with wPI = 0.75, MPI = 321k, and MPtBS = 91k at T = 40ûC, τPI/τPtBS = 1 and M/Me = 55 and 8.3 for PI and PtBS. Under small strains, this blend exhibited sharp, single-step terminal relaxation as similar to monodisperse homopolymers, thereby behaving as a ``quasi-monodisperse'' material. Under large step strains, the blend exhibited moderate nonlinear damping known as the type-A damping for entangled monodisperse homopolymers. Nevertheless, PI had M/Me = 55 in that blend, and homopolymers having such a large M/Me ratio exhibit very strong type-C damping. Thus, as compared to homopolymers, the nonlinearity was suppressed in the PI/PtBS blend having the large M/Me ratio. This suppression is discussed in relation to the slow Rouse retraction of the coexisting PtBS chains (having M/Me = 8.3 in the blend).

Final Report for Fractionation and Separation of Polydisperse Nanoparticles into Distinct Monodisperse Fractions Using CO2 Expanded Liquids

Energy Technology Data Exchange (ETDEWEB)

Chistopher Roberts

2007-08-31

The overall objective of this project was to facilitate efficient fractionation and separation of polydisperse metal nanoparticle populations into distinct monodisperse fractions using the tunable solvent properties of gas expanded liquids. Specifically, the dispersibility of ligand-stabilized nanoparticles in an organic solution was controlled by altering the ligand-solvent interaction (solvation) by the addition of carbon dioxide (CO{sub 2}) gas as an antisolvent (thereby tailoring the bulk solvent strength) in a custom high pressure apparatus developed in our lab. This was accomplished by adjusting the CO{sub 2} pressure over the liquid dispersion, resulting in a simple means of tuning the nanoparticle precipitation by size. Overall, this work utilized the highly tunable solvent properties of organic/CO{sub 2} solvent mixtures to selectively size-separate dispersions of polydisperse nanoparticles (ranging from 1 to 20 nm in size) into monodisperse fractions ({+-}1nm). Specifically, three primary tasks were performed to meet the overall objective. Task 1 involved the investigation of the effects of various operating parameters (such as temperature, pressure, ligand length and ligand type) on the efficiency of separation and fractionation of Ag nanoparticles. In addition, a thermodynamic interaction energy model was developed to predict the dispersibility of different sized nanoparticles in the gas expanded liquids at various conditions. Task 2 involved the extension of the experimental procedures identified in task 1 to the separation of other metal particles used in catalysis such as Au as well as other materials such as semiconductor particles (e.g. CdSe). Task 3 involved using the optimal conditions identified in tasks 1 and 2 to scale up the process to handle sample sizes of greater than 1 g. An experimental system was designed to allow nanoparticles of increasingly smaller sizes to be precipitated sequentially in a vertical series of high pressure vessels by

Sonochemical synthesis of silica particles and their size control

Energy Technology Data Exchange (ETDEWEB)

Kim, Hwa-Min [Advanced Materials and Chemical Engineering, Catholic University of Daegu, Gyeongbuk 38430 (Korea, Republic of); Lee, Chang-Hyun [Electronic and Electrical Engineering, Catholic University of Daegu, Gyeongbuk 38430 (Korea, Republic of); Kim, Bonghwan, E-mail: bhkim@cu.ac.kr [Electronic and Electrical Engineering, Catholic University of Daegu, Gyeongbuk 38430 (Korea, Republic of)

2016-09-01

Graphical abstract: - Highlights: • Silica particles were easily prepared by an ultrasound-assisted sol–gel method. • The particle size was controlled by the ammonium hydroxide/water molar ratio. • The size-controlled diameter of silica particles ranged from 40 to 400 nm. • The particles were formed in a relatively short reaction time. - Abstract: Using an ultrasound-assisted sol–gel method, we successfully synthesized very uniformly shaped, monodisperse, and size-controlled spherical silica particles from a mixture of ethanol, water, and tetraethyl orthosilicate in the presence of ammonia as catalyst, at room temperature. The diameters of the silica particles were distributed in the range from 40 to 400 nm; their morphology was well characterized by scanning electron microscopy. The silica particle size could be adjusted by choosing suitable concentrations of ammonium hydroxide and water, which in turn determined the nucleation and growth rates of the particles during the reaction. This sonochemical-based silica synthesis offers an alternative way to produce spherical silica particles in a relatively short reaction time. Thus, we suggest that this simple, low-cost, and efficient method of preparing uniform silica particles of various sizes will have practical and wide-ranging industrial applicability.

Method of Making an Electroactive Sensing/Actuating Material for Carbon Nanotube Polymer Composite

Science.gov (United States)

Ounaies, Zoubeida (Inventor); Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Draughon, Gregory K. (Inventor)

2009-01-01

An electroactive sensing or actuating material comprises a composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation of the composite when such composite is affected by an external stimulus. In another embodiment, the composite comprises a, third component of micro -sized to nano-sized particles of an electroactive ceramic that is also incorporated in the polymer matrix. The method for making the three-phase composite comprises either incorporating the carbon nanotubes in the polymer matrix before incorporation of the particles of ceramic or mixing the carbon nanotubes and particles of ceramic together in a solution before incorporation in the polymer matrix.

Strippable core-shell polymer emulsion for decontamination of radioactive surface contamination

International Nuclear Information System (INIS)

Hwang, Ho-Sang; Seo, Bum-Kyoung; Lee, Kune-Woo

2011-01-01

In this study, the core-shell composite polymer for decontamination from the surface contamination was synthesized by the method of emulsion polymerization and blends of polymers. The strippable polymer emulsion is composed of the poly(styrene-ethyl acrylate) [poly(St-EA)] composite polymer, poly(vinyl alcohol) (PVA) and polyvinylpyrrolidone (PVP). The morphology of the poly(St-EA) composite emulsion particle was core-shell structure, with polystyrene (PS) as the core and poly(ethyl acrylate) (PEA) as the shell. Core-shell polymers of styrene (St)/ethyl acrylate (EA) pair were prepared by sequential emulsion polymerization in the presence of sodium dodecyl sulfate (SDS) as an emulsifier using ammonium persulfate (APS) as an initiator. Related tests and analysis confirmed the success in synthesis of composite polymer. The products are characterized by FT-IR spectroscopy, TGA that were used, respectively, to show the structure, the thermal stability of the prepared polymer. Two-phase particles with a core-shell structure were obtained in experiments where the estimated glass transition temperature and the morphologies of emulsion particles. Decontamination factors of the strippable polymeric emulsion were evaluated with the polymer blend contents. (author)

Development of polymer hybrid materials and analyzing techniques for their depletions

International Nuclear Information System (INIS)

Takaya, Haruo; Kobayashi, Yoshinori; Hirata, Koichi; Nakahara, Hisae; Kinugasa, Shinichi; Kamiya, Yoshinori

1999-01-01

The purpose of this research project was to develop new methods for evaluation and analysis of deterioration of polymer materials under radiological environment and its complicated environment including chemical effects. Furthermore, a screening and development for new radio-resistant polymer materials were attempted. In 1996, the third year of this project, the effects of γ-ray exposure on cardo-type polymers, novel high performance molecules were investigated and the early radiochemical changes due to the exposure were studied according to measurement of the life-time of cation. Cardo-type polymers were exposed to γ-ray and the changes in the molecular size and its distribution were analyzed by size exclusion chromatography and multi-angle laser light scattering (SEC/MALLS). Two cardo-type polymers, PI-BP and PA-T were used as the test subjects and polystyrene was as the standard control. Three membranes made from these three polymers were exposed to γ-ray at 0.2-1.2 MGy. The exposed membranes were applied onto SEC/MALLS after dissolving in NMP. The molecular weight of PI-BP was decreased as an increase of the radiation dose and there appeared a peak in a low molecular range when exposed at higher than 0.4 MGy. The molecular weight was decreased depending to the dose for all of the two cardo-type polymers and the control polystyrene sample. The ratio, Mw/Mn for PI-BP was decreased as an increase of the dose, whereas the ratio for PA-T was hardly changed by the exposure. On the contrary, the ratio for the polystyrene sample was greatly changed as an increase of the dose. These results suggest that various molecular-sized chains were produced by the exposure from the molecule, of which size was mono-dispersed before the exposure. (M.N.)

Hydrophilic segmented block copolymers based on poly(ethylene oxide) and monodisperse amide segments

NARCIS (Netherlands)

Husken, D.; Feijen, Jan; Gaymans, R.J.

2007-01-01

Segmented block copolymers based on poly(ethylene oxide) (PEO) flexible segments and monodisperse crystallizable bisester tetra-amide segments were made via a polycondensation reaction. The molecular weight of the PEO segments varied from 600 to 4600 g/mol and a bisester tetra-amide segment (T6T6T)

Self-Assembly Kinetics of Colloidal Particles inside Monodispersed Micro-Droplet and Fabrication of Anisotropic Photonic Crystal Micro-Particles

Directory of Open Access Journals (Sweden)

Ming-Yu Zhang

2016-09-01

Full Text Available A new microfluidic approach to preparing anisotropic colloidal photonic crystal microparticles is developed and the self-assembly kinetics of colloidal nanoparticles is discussed. Based on the “coffee ring” effect in the self-assembly process of colloidal silica particle in strong solvent extraction environment, we successfully prepared anisotropic photonic crystal microparticles with different shapes and improved optical properties. The shapes and optical properties of photonic crystal microparticles can be controlled by adjusting the droplet size and extraction rate. We studied the self-assembly mechanism of colloidal silica particles in strong solvent extraction environment, which has potential applications in a variety of fields including optical communication technology, environmental response, photo-catalysis and chromic material.

A novel process route for the production of spherical SLS polymer powders

Energy Technology Data Exchange (ETDEWEB)

Schmidt, Jochen; Sachs, Marius; Blümel, Christina; Winzer, Bettina; Toni, Franziska; Wirth, Karl-Ernst; Peukert, Wolfgang [Institute of Particle Technology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Cauerstraße 4, D-91058 Erlangen (Germany)

2015-05-22

Currently, rapid prototyping gradually is transferred to additive manufacturing opening new applications. Especially selective laser sintering (SLS) is promising. One drawback is the limited choice of polymer materials available as optimized powders. Powders produced by cryogenic grinding show poor powder flowability resulting in poor device quality. Within this account we present a novel process route for the production of spherical polymer micron-sized particles of good flowability. The feasibility of the process chain is demonstrated for polystyrene e. In a first step polymer microparticles are produced by a wet grinding method. By this approach the mean particle size and the particle size distribution can be tuned between a few microns and several 10 microns. The applicability of this method will be discussed for different polymers and the dependencies of product particle size distribution on stressing conditions and process temperature will be outlined. The comminution products consist of microparticles of irregular shape and poor powder flowability. An improvement of flowability of the ground particles is achieved by changing their shape: they are rounded using a heated downer reactor. The influence of temperature profile and residence time on the product properties will be addressed applying a viscous-flow sintering model. To further improve the flowability of the cohesive spherical polymer particles nanoparticles are adhered onto the microparticles’ surface. The improvement of flowability is remarkable: rounded and dry-coated powders exhibit a strongly reduced tensile strength as compared to the comminution product. The improved polymer powders obtained by the process route proposed open new possibilities in SLS processing including the usage of much smaller polymer beads.

A novel process route for the production of spherical SLS polymer powders

International Nuclear Information System (INIS)

Schmidt, Jochen; Sachs, Marius; Blümel, Christina; Winzer, Bettina; Toni, Franziska; Wirth, Karl-Ernst; Peukert, Wolfgang

2015-01-01

Currently, rapid prototyping gradually is transferred to additive manufacturing opening new applications. Especially selective laser sintering (SLS) is promising. One drawback is the limited choice of polymer materials available as optimized powders. Powders produced by cryogenic grinding show poor powder flowability resulting in poor device quality. Within this account we present a novel process route for the production of spherical polymer micron-sized particles of good flowability. The feasibility of the process chain is demonstrated for polystyrene e. In a first step polymer microparticles are produced by a wet grinding method. By this approach the mean particle size and the particle size distribution can be tuned between a few microns and several 10 microns. The applicability of this method will be discussed for different polymers and the dependencies of product particle size distribution on stressing conditions and process temperature will be outlined. The comminution products consist of microparticles of irregular shape and poor powder flowability. An improvement of flowability of the ground particles is achieved by changing their shape: they are rounded using a heated downer reactor. The influence of temperature profile and residence time on the product properties will be addressed applying a viscous-flow sintering model. To further improve the flowability of the cohesive spherical polymer particles nanoparticles are adhered onto the microparticles’ surface. The improvement of flowability is remarkable: rounded and dry-coated powders exhibit a strongly reduced tensile strength as compared to the comminution product. The improved polymer powders obtained by the process route proposed open new possibilities in SLS processing including the usage of much smaller polymer beads

High Resolution Shear Profile Measurements in Entangled Polymers

KAUST Repository

Hayes, Keesha A.

2008-11-17

We use confocal microscopy and particle image velocimetry to visualize motion of 250-300 nm. fluorescent tracer particles in entangled polymers subject to a rectilinear shear flow. Our results show linear velocity profiles in polymer solutions spanning a wide range of molecular weights and number of entanglements (8≤Z≤56), but reveal large differences between the imposed and measured shear rates. These findings disagree with recent reports that shear banding is a characteristic flow response of entangled polymers, and instead point to interfacial slip as an important source of strain loss. © 2008 The American Physical Society.

Growth of polymer nanoparticles in microemulsion polymerization initiated with γ ray

International Nuclear Information System (INIS)

Xu Xiangling; Ge Xuewu; Ye Qiang; Zhang Zhicheng; Zuo Ju; Niu Aizhen; Zhang Manwei

1999-01-01

In microemulsion polymerization of styrene, butyl acrylate and methyl methacrylate initiated with gamma ray, growth of polymer nanoparticles was observed with photon correlation spectroscopy, and the conversion curve was recorded with a dilatometer. There is some similarity in the growth of polymer particles. The size of polymer particles rapidly increases up to their maximum at the early stage. With the increase of conversion, the large particles supply their monomer to newly formed particles and become smaller. In all these three microemulsion polymerizations, the evidence of continuous nucleation was observed. When monomer is styrene or butyl acrylate, a plateau of polymerization rate emerges. When monomer is methyl methacrylate, no plateau of polymerization is observed

Method of preparing Ru-immobilized polymer-supported catalyst for hydrogen generation from NaBH{sub 4} solution

Energy Technology Data Exchange (ETDEWEB)

Chen, Ching-Wen; Chen, Chuh-Yung; Huang, Yao-Hui [Department of Chemical Engineering, National Cheng Kung University, No.1, University Road, Tainan City 70101 (China)

2009-03-15

A method of preparing a polymer-supported catalyst for hydrogen generation is introduced in this article. This polymer-supported catalyst is the structure of ruthenium (Ru) nanoparticle immobilized on a monodisperse polystyrene (PSt) microsphere. The diameter of the Ru nanoparticle is around 16 nm, and the diameter of the PSt microsphere is 2.65 um. This preparation method is accomplished by two unique techniques: one is sodium lauryl sulfate/sodium formaldehyde sulfoxylate (SLS/SFS) interface-initiated system, the other is 2-methacrylic acid 3-(bis-carboxymethylamino)-2-hydroxy-propyl ester (GMA-IDA) chelating monomer. By taking advantage of these two techniques, Ru{sup 3+} ion will be chelated and then reduced to Ru{sup (0)} nanoparticle over PSt surface predominantly. The hydrolysis of alkaline sodium borohydride (NaBH{sub 4}) solution catalyzed by this Ru-immobilized polymer-supported catalyst is also examined in this article. It reveals that the hydrogen generation rate is 215.9 ml/min g-cat. in a diluted solution containing 1 wt.% NaBH{sub 4} and 1 wt.% NaOH, and this Ru-immobilized polymer-supported catalyst could be recycled during the reaction. (author)

Highly temperature responsive core-shell magnetic particles: synthesis, characterization and colloidal properties.

Science.gov (United States)

Rahman, Md Mahbubor; Chehimi, Mohamed M; Fessi, Hatem; Elaissari, Abdelhamid

2011-08-15

Temperature responsive magnetic polymer submicron particles were prepared by two step seed emulsion polymerization process. First, magnetic seed polymer particles were obtained by emulsion polymerization of styrene using potassium persulfate (KPS) as an initiator and divinylbenzne (DVB) as a cross-linker in the presence of oil-in-water magnetic emulsion (organic ferrofluid droplets). Thereafter, DVB cross-linked magnetic polymer particles were used as seed in the precipitation polymerization of N-isopropylacrylamide (NIPAM) to induce thermosensitive PNIPAM shell onto the hydrophobic polymer surface of the cross-linked magnetic polymer particles. To impart cationic functional groups in the thermosensitive PNIPAM backbone, the functional monomer aminoethylmethacrylate hydrochloride (AEMH) was used to polymerize with NIPAM while N,N'-methylenebisacrylamide (MBA) and 2, 2'-azobis (2-methylpropionamidine) dihydrochloride (V-50) were used as a cross-linker and as an initiator respectively. The effect of seed to monomer (w/w) ratio along with seed nature on the final particle morphology was investigated. Dynamic light scattering (DLS) results demonstrated particles swelling at below volume phase transition temperature (VPTT) and deswelling above the VPTT. The perfect core (magnetic) shell (polymer) structure of the particles prepared was confirmed by Transmission Electron Microscopy (TEM). The chemical composition of the particles were determined by thermogravimetric analysis (TGA). The effect of temperature, pH, ionic strength on the colloidal properties such as size and zeta potential of the micron sized thermo-sensitive magnetic particles were also studied. In addition, a short mechanistic discussion on the formation of core-shell morphology of magnetic polymer particles has also been discussed. Copyright © 2011 Elsevier Inc. All rights reserved.

Polydisperse particle-driven gravity currents in non-rectangular cross section channels

Science.gov (United States)

Zemach, T.

2018-01-01

We consider a high-Reynolds-number gravity current generated by polydisperse suspension of n types of particles distributed in a fluid of density ρi. Each class of particles in suspension has a different settling velocity. The current propagates along a channel of non-rectangular cross section into an ambient fluid of constant density ρa. The bottom and top of the channel are at z = 0, H, and the cross section is given by the quite general form -f1(z) ≤ y ≤ f2(z) for 0 ≤ z ≤ H. The flow is modeled by the one-layer shallow-water equations obtained for the time-dependent motion. We solve the problem by a finite-difference numerical code to present typical height h, velocity u, and mass fractions of particle (concentrations) (ϕ( j), j = 1, …, n) profiles. The runout length of suspensions in channels of power-law cross sections is analytically predicted using a simplified depth-averaged "box" model. We demonstrate that any degree of polydispersivity adds to the runout length of the currents, relative to that of equivalent monodisperse currents with an average settling velocity. The theoretical predictions are supported by the available experimental data. The present approach is a significant generalization of the particle-driven gravity current problem: on the one hand, now the monodisperse current in non-rectangular channels is a particular case of n = 1. On the other hand, the classical formulation of polydisperse currents for a rectangular channel is now just a particular case, f(z) = const., in the wide domain of cross sections covered by this new model.

The Isolation of DNA by Polycharged Magnetic Particles: An Analysis of the Interaction by Zeta Potential and Particle Size.

Science.gov (United States)

Haddad, Yazan; Xhaxhiu, Kledi; Kopel, Pavel; Hynek, David; Zitka, Ondrej; Adam, Vojtech

2016-04-20

Magnetic isolation of biological targets is in major demand in the biotechnology industry today. This study considers the interaction of four surface-modified magnetic micro- and nanoparticles with selected DNA fragments. Different surface modifications of nanomaghemite precursors were investigated: MAN37 (silica-coated), MAN127 (polyvinylpyrrolidone-coated), MAN158 (phosphate-coated), and MAN164 (tripolyphosphate-coated). All particles were positive polycharged agglomerated monodispersed systems. Mean particle sizes were 0.48, 2.97, 2.93, and 3.67 μm for MAN37, MAN127, MAN164, and MAN158, respectively. DNA fragments exhibited negative zeta potential of -0.22 mV under binding conditions (high ionic strength, low pH, and dehydration). A decrease in zeta potential of particles upon exposure to DNA was observed with exception of MAN158 particles. The measured particle size of MAN164 particles increased by nearly twofold upon exposure to DNA. Quantitative PCR isolation of DNA with a high retrieval rate was observed by magnetic particles MAN127 and MAN164. Interaction between polycharged magnetic particles and DNA is mediated by various binding mechanisms such as hydrophobic and electrostatic interactions. Future development of DNA isolation technology requires an understanding of the physical and biochemical conditions of this process.

Assembly of Fe3O4 nanoparticles on SiO2 monodisperse spheres

Indian Academy of Sciences (India)

Assembly of Fe3O4 nanoparticles on SiO2 monodisperse spheres. K C BARICK and D BAHADUR*. Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay,. Mumbai 400 076, India. Abstract. The assembly of superparamagnetic Fe3O4 nanoparticles on submicroscopic SiO2 ...

Controlled Release from Core-Shell Nano porous Silica Particles for Corrosion Inhibition of Aluminum Alloys

International Nuclear Information System (INIS)

Jiang, X.; Rathod, Sh.; Shah, P.; Brinker, C.J.; Jiang, X.; Jiang, Y.; Liu, N.; Xu, H.; Brinker, C.J.

2011-01-01

Cerium (Ce) corrosion inhibitors were encapsulated into hexagonally ordered nanoporous silica particles via single-step aerosol-assisted self-assembly. The core/shell structured particles are effective for corrosion inhibition of aluminum alloy AA2024-T3. Numerical simulation proved that the core-shell nanostructure delays the release process. The effective diffusion coefficient elucidated from release data for monodisperse particles in water was 1.0x10-14 m 2 s for Ce 3+ compared to 2.5x10-13 m 2 s for NaCl. The pore size, pore surface chemistry, and the inhibitor solubility are crucial factors for the application. Microporous hydrophobic particles encapsulating a less soluble corrosion inhibitor are desirable for long-term corrosion inhibition.

Preparation of spherical particles by vibrating orifice technique

Science.gov (United States)

Shibata, Shuichi; Tomizawa, Atsushi; Yoshikawa, Hidemi; Yano, Tetsuji; Yamane, Masayuki

2000-05-01

Preparation of micrometer-sized spherical particles containing Rhodamine 6G (R6G) has been investigated for the spherical cavity micro-laser. Using phenyl triethoxy silane (PTES) as a starting material, R6G-doped monodisperse spherical particles were prepared by the vibrating orifice technique. Processing consists of two major processes: (1) Hydrolysis and polymerization of PTES and (2) Droplet formation from PTES oligomers by vibrating orifice technique. A cylindrical liquid jet passing through the orifice of 10 and 20 micrometers in diameter breaks up into equal- sized droplets by mechanical vibration. Alcohol solvent of these droplets was evaporated during flying with carrier gas and subsequently solidified in ammonium water trap. For making smooth surface and god shaped particles, control of molecular weight of PTES oligomer was essential. R6G-doped hybrid spherical particles of 4 to 10 micrometers size of cavity structure were successfully obtained. The spherical particles were pumped by a second harmonic pulse of Q- switched Nd:YAG laser and laser emission peaks were observed at wavelengths which correspond to the resonance modes.

Deformation and degradation of polymers in ultra-high-pressure liquid chromatography

NARCIS (Netherlands)

Uliyanchenko, E.; van der Wal, S.; Schoenmakers, P.J.

2011-01-01

Ultra-high-pressure liquid chromatography (UHPLC) using columns packed with sub-2 μm particles has great potential for separations of many types of complex samples, including polymers. However, the application of UHPLC for the analysis of polymers meets some fundamental obstacles. Small particles

Fabrication of shape-controllable polyaniline micro/nanostructures on organic polymer surfaces: obtaining spherical particles, wires, and ribbons.

Science.gov (United States)

Zhong, Wenbin; Wang, Yongxin; Yan, Yan; Sun, Yufeng; Deng, Jianping; Yang, Wantai

2007-04-19

A novel strategy was developed in order to prepare various micro/nanostructured polyanilines (PANI) on polymer substrates. The strategy involved two main steps, i.e., a grafting polymerization of acrylate acid (AA) onto the surface of a polypropylene (PP) film and subsequently an oxidative polymerization of aniline on the grafted surface. By tuning the conformation of the surface-grafted poly acrylate acid (PAA) brushes, as well as the ratio of AA to aniline, the shape of the PANIs fixated onto the surfaces of the polymer substrate could be controlled to go from spherical particles to nanowires and eventually to nanoribbons. In these structures, the PAA brushes not only acted as templates but also as dopants of PANI, and thereby, the nanostructured PANIs could be strongly bonded with the substrate. In addition, the surface of the PP films grafted with polyaniline nanowires and nanoribbons displayed superhydrophobicity with contact angles for water of approxiamtely 145 and 151 degrees , respectively.

Fabrication and characterisation of gold nano-particle modified polymer monoliths for flow-through catalytic reactions and their application in the reduction of hexacyanoferrate

International Nuclear Information System (INIS)

Floris, Patrick; Twamley, Brendan; Nesterenko, Pavel N.; Paull, Brett; Connolly, Damian

2014-01-01

Polymer monoliths in capillary (100 μm i.d.) and polypropylene pipette tip formats (vol: 20 μL) were modified with gold nano-particles (AuNP) and subsequently used for flow-through catalytic reactions. Specifically, methacrylate monoliths were modified with amine-reactive monomers using a two-step photografting method and then reacted with ethylenediamine to provide amine attachment sites for the subsequent immobilisation of 4 nm, 7 nm or 16 nm AuNP. This was achieved by flushing colloidal suspensions of gold nano-particles through each aminated polymer monolith which resulted in a multi-point covalent attachment of gold via the lone pair of electrons on the nitrogen of the free amine groups. Field emission scanning electron microscopy and scanning capacitively coupled conductivity detection was used to characterise the surface coverage of AuNP on the monoliths. The catalytic activity of AuNP immobilised on the polymer monoliths in both formats was then demonstrated using the reduction of Fe(III) to Fe(II) by sodium borohydride as a model reaction by monitoring the reduction in absorbance of the hexacyanoferrate (III) complex at 420 nm. Catalytic activity was significantly enhanced on monoliths modified with smaller AuNP with almost complete reduction (95 %) observed when using monoliths agglomerated with 7 nm AuNPs. (author)

On the interpolation of light-scattering responses from irregularly shaped particles

Science.gov (United States)

Videen, Gorden; Zubko, Evgenij; Arnold, Jessica A.; MacCall, Benjamin; Weinberger, Alycia J.; Shkuratov, Yuriy; Muñoz, Olga

2018-05-01

Common particle characteristics needed for many applications may include size, eccentricity, porosity and refractive index. Determining such characteristics from scattered light is a primary goal of remote sensing. For other applications, like differentiating a hazardous particle from the natural background, information about higher fidelity particle characteristics may be required, including specific shape or chemical composition. While a complete characterization of a particle system from its scattered light through the inversion process remains unachievable, great strides have been made in providing information in the form of constraints on particle characteristics. Recent advances have been made in quantifying the characteristics of polydispersions of irregularly shaped particles by making comparisons of the light-scattering signals from model simulant particles. We show that when the refractive index is changed, the light-scattering characteristics from polydispersions of such particles behave monotonically over relatively large parameter ranges compared with those of monodisperse distributions of particles having regular shapes, like spheres, spheroids, etc. This allows for their properties to be interpolated, which results in a significant reduction of the computational load when performing inversions.

Preparation and in vitro evaluation of folate-receptor-targeted SPION-polymer micelle hybrids for MRI contrast enhancement in cancer imaging

Science.gov (United States)

Mahajan, Shveta; Koul, Veena; Choudhary, Veena; Shishodia, Gauri; Bharti, Alok C.

2013-01-01

Polymer-SPION hybrids were investigated for receptor-mediated localization in tumour tissue. Superparamagnetic iron oxide nanoparticles (SPIONs) prepared by high-temperature decomposition of iron acetylacetonate were monodisperse (9.27 ± 3.37 nm), with high saturation magnetization of 76.8 emu g-1. Amphiphilic copolymers prepared from methyl methacrylate and PEG methacrylate by atom transfer radical polymerization were conjugated with folic acid (for folate-receptor specificity). The folate-conjugated polymer had a low critical micellar concentration (0.4 mg l-1), indicating stability of the micellar formulation. SPION-polymeric micelle clusters were prepared by desolvation of the SPION dispersion/polymer solution in water. Magnetic resonance imaging of the formulation revealed very good contrast enhancement, with transverse (T2) relaxivity of 260.4 mM-1 s-1. The biological evaluation of the SPION micelles included cellular viability assay (MTT) and uptake in HeLa cells. These studies demonstrated the potential use of these nanoplatforms for imaging and targeting.

Radiation synthesis of polymer polyol

International Nuclear Information System (INIS)

Guo Jianmei; Zeng Xinmiao; Zhou Chengfei; Cao Wei; Zhai Tong; Wu Dezhen

2010-01-01

The polymer polyol was synthesized by γ irradiation. The properties of polymer polyol synthesized with different radiation dose were studied. The experiment result showed the radiation dose hadn't significant influence on the hydroxyl value of polymer polyol. The sample with different solid content had different hydroxyl value. When the radiation dose is between 1 to 12 kGy, the viscosity and hydroxyl value of polymer polyol were increased with the increment of radiation dose. When radiation dose is between 1 to 12 kGy, with the increment of radiation dose, viscosity of polymer polyol was rapidly increased, and the content solid of sample has few change. When radiation dose is higher than 20 kGy, the viscosity and hydroxyl value of polymer polyol have gradually increase with the increment of radiation dose. The size of polymer particles is 0.1-0.6 μm. The value of 150 mesh filter was 100%. The polymer polyol may be used as PU foam and elastomer. (authors)

Micromechanical analysis of a hybrid composite—effect of boron carbide particles on the elastic properties of basalt fiber reinforced polymer composite

Science.gov (United States)

Krishna Golla, Sai; Prasanthi, P.

2016-11-01

A fiber reinforced polymer (FRP) composite is an important material for structural application. The diversified application of FRP composites has become the center of attention for interdisciplinary research. However, improvements in the mechanical properties of this class of materials are still under research for different applications. The reinforcement of inorganic particles in a composite improves its structural properties due to their high stiffness. The present research work is focused on the prediction of the mechanical properties of the hybrid composites where continuous fibers are reinforced in a micro boron carbide particle mixed polypropylene matrix. The effectiveness of the addition of 30 wt. % of boron carbide (B4C) particle contributions regarding the longitudinal and transverse properties of the basalt fiber reinforced polymer composite at various fiber volume fractions is examined by finite element analysis (FEA). The experimental approach is the best way to determine the properties of the composite but it is expensive and time-consuming. Therefore, the finite element method (FEM) and analytical methods are the viable methods for the determination of the composite properties. The FEM results were obtained by adopting a micromechanics approach with the support of FEM. Assuming a uniform distribution of reinforcement and considering one unit-cell of the whole array, the properties of the composite materials are determined. The predicted elastic properties from FEA are compared with the analytical results. The results suggest that B4C particles are a good reinforcement for the enhancement of the transverse properties of basalt fiber reinforced polypropylene.

Ultrasmooth, Highly Spherical Monocrystalline Gold Particles for Precision Plasmonics

KAUST Repository

Lee, You-Jin

2013-12-23

Ultrasmooth, highly spherical monocrystalline gold particles were prepared by a cyclic process of slow growth followed by slow chemical etching, which selectively removes edges and vertices. The etching process effectively makes the surface tension isotropic, so that spheres are favored under quasi-static conditions. It is scalable up to particle sizes of 200 nm or more. The resulting spherical crystals display uniform scattering spectra and consistent optical coupling at small separations, even showing Fano-like resonances in small clusters. The high monodispersity of the particles we demonstrate should facilitate the self-assembly of nanoparticle clusters with uniform optical resonances, which could in turn be used to fabricate optical metafluids. Narrow size distributions are required to control not only the spectral features but also the morphology and yield of clusters in certain assembly schemes. © 2013 American Chemical Society.

Synthesis and characterization of monodispersed silver nanoparticles

Science.gov (United States)

Jegatha Christy, A.; Umadevi, M.

2012-09-01

Synthesis of silver nanoparticles (NPs) has become a fascinating and important field of applied chemical research. In this paper silver NPs were prepared using silver nitrate (AgNO3), gelatin, and cetyl trimethyl ammonium bromide (CTAB). The prepared silver NPs were exposed under the laser ablation. In our photochemical procedure, gelatin acts as a biopolymer and CTAB acts as a reducing agent. The appearance of surface plasmon band around 410 nm indicates the formation of silver NPs. The nature of the prepared silver NPs in the face-centered cubic (fcc) structure are confirmed by the peaks in the x-ray diffraction (XRD) pattern corresponding to (111), (200), (220) and (311) planes. Monodispersed, stable, spherical silver NPs with diameter about 10 nm were obtained and confirmed by high-resolution transmission electron microscope (HRTEM).

Synthesis and characterization of monodispersed silver nanoparticles

International Nuclear Information System (INIS)

Christy, A Jegatha; Umadevi, M

2012-01-01

Synthesis of silver nanoparticles (NPs) has become a fascinating and important field of applied chemical research. In this paper silver NPs were prepared using silver nitrate (AgNO 3 ), gelatin, and cetyl trimethyl ammonium bromide (CTAB). The prepared silver NPs were exposed under the laser ablation. In our photochemical procedure, gelatin acts as a biopolymer and CTAB acts as a reducing agent. The appearance of surface plasmon band around 410 nm indicates the formation of silver NPs. The nature of the prepared silver NPs in the face-centered cubic (fcc) structure are confirmed by the peaks in the x-ray diffraction (XRD) pattern corresponding to (111), (200), (220) and (311) planes. Monodispersed, stable, spherical silver NPs with diameter about 10 nm were obtained and confirmed by high-resolution transmission electron microscope (HRTEM). (paper)

Controlled Release from Core-Shell Nanoporous Silica Particles for Corrosion Inhibition of Aluminum Alloys

Directory of Open Access Journals (Sweden)

Xingmao Jiang

2011-01-01

Full Text Available Cerium (Ce corrosion inhibitors were encapsulated into hexagonally ordered nanoporous silica particles via single-step aerosol-assisted self-assembly. The core/shell structured particles are effective for corrosion inhibition of aluminum alloy AA2024-T3. Numerical simulation proved that the core-shell nanostructure delays the release process. The effective diffusion coefficient elucidated from release data for monodisperse particles in water was 1.0×10−14 m2s for Ce3+ compared to 2.5×10−13 m2s for NaCl. The pore size, pore surface chemistry, and the inhibitor solubility are crucial factors for the application. Microporous hydrophobic particles encapsulating a less soluble corrosion inhibitor are desirable for long-term corrosion inhibition.

Volatile particles formation during PartEmis: a modelling study

Directory of Open Access Journals (Sweden)

X. Vancassel

2004-01-01

Full Text Available A modelling study of the formation of volatile particles in a combustor exhaust has been carried out in the frame of the PartEmis European project. A kinetic model has been used in order to investigate nucleation efficiency of the H2O-H2SO4 binary mixture in the sampling system. A value for the fraction of the fuel sulphur S(IV converted into S(VI has been indirectly deduced from comparisons between model results and measurements. In the present study, ranges between roughly 2.5% and 6%, depending on the combustor settings and on the value assumed for the parameter describing sulphuric acid wall losses. Soot particles hygroscopicity has also been investigated as their activation is a key parameter for contrail formation. Growth factors of monodisperse particles exposed to high relative humidity (95% have been calculated and compared with experimental results. The modelling study confirms that the growth factor increases as the soot particle size decreases.

Aqueous dispersion of monodisperse magnetic iron oxide nanocrystals through phase transfer

International Nuclear Information System (INIS)

Yu, William W; Chang, Emmanuel; Sayes, Christie M; Drezek, Rebekah; Colvin, Vicki L

2006-01-01

A facile method was developed for completely transferring high quality monodisperse iron oxide nanocrystals from organic solvents to water. The as-prepared aqueous dispersions of iron oxide nanocrystals were extremely stable and could be functionalized for bioconjugation with biomolecules. These iron oxide nanocrystals showed negligible cytotoxicity to human breast cancer cells (SK-BR-3) and human dermal fibroblast cells. This method is general and versatile for many organic solvent-synthesized nanoparticles, including fluorescent semiconductor nanocrystals

Particle size dependence of CO tolerance of anode PtRu catalysts for polymer electrolyte fuel cells

Science.gov (United States)

Yamanaka, Toshiro; Takeguchi, Tatsuya; Wang, Guoxiong; Muhamad, Ernee Noryana; Ueda, Wataru

An anode catalyst for a polymer electrolyte fuel cell must be CO-tolerant, that is, it must have the function of hydrogen oxidation in the presence of CO, because hydrogen fuel gas generated by the steam reforming process of natural gas contains a small amount of CO. In the present study, PtRu/C catalysts were prepared with control of the degree of Pt-Ru alloying and the size of PtRu particles. This control has become possible by a new method of heat treatment at the final step in the preparation of catalysts. The CO tolerances of PtRu/C catalysts with the same degree of Pt-Ru alloying and with different average sizes of PtRu particles were thus compared. Polarization curves were obtained with pure H 2 and CO/H 2 (CO concentrations of 500-2040 ppm). It was found that the CO tolerance of highly dispersed PtRu/C (high dispersion (HD)) with small PtRu particles was much higher than that of poorly dispersed PtRu/C (low dispersion (LD)) with large metal particles. The CO tolerance of PtRu/C (HD) was higher than that of any commercial PtRu/C. The high CO tolerance of PtRu/C (HD) is thought to be due to efficient concerted functions of Pt, Ru, and their alloy.

Dynamics of particle chain formation in a liquid polymer under ac electric field: modeling and experiments

International Nuclear Information System (INIS)

Belijar, G; Valdez-Nava, Z; Diaham, S; Laudebat, L; Lebey, T; Jones, T B

2017-01-01

Polymer/ceramic composite materials are of great interest for their many potential applications because of their ability to combine at least two properties of the constitutive elements: particles and matrix. In most cases, such enhanced properties are required only in one direction. Orthotropic materials can be elaborated by applying an ac electric field to form particle chain structures in the direction of the electric field due to the dielectrophoretic interactions affecting the particles. However, there is still a lack in the understanding of the impact of the structures on the properties of the material. The aim of this study is to propose a predictive model for the evolution of the permittivity during the chain formation, by including micro- and macroscopic phenomena. The chaining model is based on dipole–dipole interactions and the dielectric permittivity is computed through a finite element method. In parallel, an experimental study is performed with online permittivity measurements of composites during chaining. The developed model is able to predict the experimental results from 1 vol% while taking into account parameters such as the resin viscosity and permittivity and the transient evolution of the applied electric field. The formation of particle chains inside a material has applications in many domains such as electrorheological fluids, anisotropic composites, self-recovery materials etc. Such a developed model is a valuable tool for the tailoring of materials. (paper)

Bio-degradable highly fluorescent conjugated polymer nanoparticles for bio-medical imaging applications.

Science.gov (United States)

Repenko, Tatjana; Rix, Anne; Ludwanowski, Simon; Go, Dennis; Kiessling, Fabian; Lederle, Wiltrud; Kuehne, Alexander J C

2017-09-07

Conjugated polymer nanoparticles exhibit strong fluorescence and have been applied for biological fluorescence imaging in cell culture and in small animals. However, conjugated polymer particles are hydrophobic and often chemically inert materials with diameters ranging from below 50 nm to several microns. As such, conjugated polymer nanoparticles cannot be excreted through the renal system. This drawback has prevented their application for clinical bio-medical imaging. Here, we present fully conjugated polymer nanoparticles based on imidazole units. These nanoparticles can be bio-degraded by activated macrophages. Reactive oxygen species induce scission of the conjugated polymer backbone at the imidazole unit, leading to complete decomposition of the particles into soluble low molecular weight fragments. Furthermore, the nanoparticles can be surface functionalized for directed targeting. The approach opens a wide range of opportunities for conjugated polymer particles in the fields of medical imaging, drug-delivery, and theranostics.Conjugated polymer nanoparticles have been applied for biological fluorescence imaging in cell culture and in small animals, but cannot readily be excreted through the renal system. Here the authors show fully conjugated polymer nanoparticles based on imidazole units that can be bio-degraded by activated macrophages.

Initiator Systems Effect on Particle Coagulation and Particle Size Distribution in One-Step Emulsion Polymerization of Styrene

Directory of Open Access Journals (Sweden)

Baijun Liu

2016-02-01

Full Text Available Particle coagulation is a facile approach to produce large-scale polymer latex particles. This approach has been widely used in academic and industrial research owing to its higher polymerization rate and one-step polymerization process. Our work was motivated to control the extent (or time of particle coagulation. Depending on reaction parameters, particle coagulation is also able to produce narrowly dispersed latex particles. In this study, a series of experiments were performed to investigate the role of the initiator system in determining particle coagulation and particle size distribution. Under the optimal initiation conditions, such as cationic initiator systems or higher reaction temperature, the time of particle coagulation would be advanced to particle nucleation period, leading to the narrowly dispersed polymer latex particles. By using a combination of the Smoluchowski equation and the electrostatic stability theory, the relationship between the particle size distribution and particle coagulation was established: the earlier the particle coagulation, the narrower the particle size distribution, while the larger the extent of particle coagulation, the larger the average particle size. Combined with the results of previous studies, a systematic method controlling the particle size distribution in the presence of particle coagulation was developed.

Tri-block copolymers with mono-disperse crystallizable diamide segments: synthesis, analysis and rheological properties

NARCIS (Netherlands)

Araichimani, A.; Gaymans, R.J.

2008-01-01

Tri-block copolymers with polyether mid-segments and mono-disperse amide end segments were synthesized, analyzed and some properties studied. The end segment was an aromatic diamide (diaramide, TΦB). The polyether mid-segment was a difunctional poly(tetramethylene oxide) (PTMO, 1000 and 2900 g/mol).

Microscopic theory for dynamics in entangled polymer nanocomposites

Science.gov (United States)

Yamamoto, Umi

New microscopic theories for describing dynamics in polymer nanocomposites are developed and applied. The problem is addressed from two distinct perspectives and using two different theoretical approaches. The first half of this dissertation studies the long-time and intermediate-time dynamics of nanoparticles in entangled and unentangled polymer melts for dilute particle concentrations. Using a combination of mode-coupling, Brownian motion, and polymer physics ideas, the nanoparticle long-time diffusion coefficients is formulated in terms of multiple length-scales, packing microstructures, and spatially-resolved polymer density fluctuation dynamics. The key motional mechanism is described via the parallel relaxation of the force exerted on the particle controlled by collective polymer constraint-release and the particle self-motion. A sharp but smooth crossover from the hydrodynamic to the non-hydrodynamic regime is predicted based on the Stokes-Einstein violation ratio as a function of all the system variables. Quantitative predictions are made for the recovery of the Stokes-Einstein law, and the diffusivity in the crossover regime agrees surprisingly well with large-scale molecular dynamics simulations for all particle sizes and chain lengths studied. The approach is also extended to address intermediate-time anomalous transport of a single nanoparticle and two-particle relative diffusion. The second half of this dissertation focuses on developing a novel dynamical theory for a liquid of infinitely-thin rods in the presence of hard spherical obstacles, aiming at a technical and conceptual extension of the existing paradigm for entangled polymer dynamics. As a fundamental theoretical development, the two-component generalization of a first-principles dynamic meanfield approach is presented. The theory enforces inter-needle topological uncrossability and needlesphere impenetrability in a unified manner, leading to a generalized theory of entanglements that

Generating high-quality single droplets for optical particle characterization with an easy setup

Science.gov (United States)

Xu, Jie; Ge, Baozhen; Meng, Rui

2018-06-01

The high-performance and micro-sized single droplet is significant for optical particle characterization. We develop a single-droplet generator (SDG) based on a piezoelectric inkjet technique with advantages of low cost and easy setup. By optimizing the pulse parameters, we achieve various size single droplets. Further investigations reveal that SDG generates single droplets of high quality, demonstrating good sphericity, monodispersity and a stable length of several millimeters.

Facile Synthesis of Monodispersed Polysulfide Spheres for Building Structural Colors with High Color Visibility and Broad Viewing Angle.

Science.gov (United States)

Li, Feihu; Tang, Bingtao; Wu, Suli; Zhang, Shufen

2017-01-01

The synthesis and assembly of monodispersed colloidal spheres are currently the subject of extensive investigation to fabricate artificial structural color materials. However, artificial structural colors from general colloidal crystals still suffer from the low color visibility and strong viewing angle dependence which seriously hinder their practical application in paints, colorimetric sensors, and color displays. Herein, monodispersed polysulfide (PSF) spheres with intrinsic high refractive index (as high as 1.858) and light-absorbing characteristics are designed, synthesized through a facile polycondensation and crosslinking process between sodium disulfide and 1,2,3-trichloropropane. Owing to their high monodispersity, sufficient surface charge, and good dispersion stability, the PSF spheres can be assembled into large-scale and high-quality 3D photonic crystals. More importantly, high structural color visibility and broad viewing angle are easily achieved because the unique features of PSF can remarkably enhance the relative reflectivity and eliminate the disturbance of scattering and background light. The results of this study provide a simple and efficient strategy to create structural colors with high color visibility, which is very important for their practical application. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The binding parameters of radiolabelled monoclonal F (ab')2 and Fab' fragments relative to immunoglobulin G in reactions with surface-bound antigens

International Nuclear Information System (INIS)

Fjeld, J.G.; Nustad, K.; Michaelsen, T.E.

1992-01-01

The binding parameters of iodine-125-labelled intact monoclonal immunoglobulin G (IgG), F(ab') 2 and Fab' fragments were compared. The study was carried out with the two monoclonal antibodies (MoAbs) K13 and K16 specific for human Ig light chains κ and λ, respectively. When testing the 125 I-MoAbs against monodisperse polymer particles coated with the specific antigens, the K a for the F(ab') 2 fragments were similar to that for IgG, while the K a for the Fab' fragments were reduced to 10%-20% of that for IgG. The number N of effective target sites revealed with Fab' was higher than with F(ab') and IgG, presumably because less surface area is occupied by the small Fab' molecules. The immunoreactive fraction F ranged according to IgG>F(ab') 2 >Fab'. The explanation of the moderate difference between the K a of the monoclonal Fab' and the divalent IgG and F(ab') 2 was that the divalent molecules were not divalently attached to the particles. When testing the same antibody preparations against humanlymphoma cells producing Ig with light chains κ or λ, the binding results were less reliable than when particles were utilised, presumably due to antigen shedding. Different MoAbs vary in their loss of immunoreactivity due to enzymatic degradation and the radiolabelling procedure. The preparation of the radiolabelled fragments should therefore be optimized for each MoAb, and evaluation is necessary before injection. Artificial targets with a low leakage of antigen, like the monodisperse polymer particles here applied, are recommended for the in vitro evaluation of the immunoreactivity of labelled MoAb preparations. (orig.)

Synergistically enhanced stability of laccase immobilized on synthesized silver nanoparticles with water-soluble polymers.

Science.gov (United States)

Cunha, M N M; Felgueiras, H P; Gouveia, I; Zille, A

2017-06-01

Silver nanoparticles (AgNPs) were synthesized by citrate reduction method in the presence of polymers, poly(ethylene glycol) (PEG), poly(vinyl alcohol) (PVA) and chitosan, used as stabilizing agents, and an oxidoreductase enzyme, laccase (Lac), with the goal of expanding the NPs antimicrobial action. AgNPs were characterized by UV-vis spectrometry, dynamic light scattering and transmission electron microscopy. As protecting agents, PEG and PVA promoted the formation of spherical uniformly-shaped, small-sized, monodispersed AgNPs (≈20nm). High Mw polymers were established as most effective in producing small-sized NPs. Chitosan's viscosity led to the formation of aggregates. Despite the decrease in Lac activity registered for the hybrid formulation, AgNPs-polymer-Lac, a significant augment in stability over time (up to 13days, at 50°C) was observed. This novel formulation displays improved synergistic performance over AgNPs-Lac or polymer-Lac conjugates, since in the former the Lac activity becomes residual at the end of 3days. By enabling many ionic interactions, chitosan restricted the mass transfer between Lac and substrate and, thus, inhibited the enzymatic activity. These hybrid nanocomposites made up of inorganic NPs, organic polymers and immobilized antimicrobial oxidoreductive enzymes represent a new class of materials with improved synergistic performance. Moreover, the Lac and the AgNPs different antimicrobial action, both in time and mechanism, may also constitute a new alternative to reduce the probability of developing resistance-associated mutations. Copyright © 2017 Elsevier B.V. All rights reserved.

Performance enhancement of quantum dot-sensitized solar cells based on polymer nano-composite catalyst

International Nuclear Information System (INIS)

Seo, Hyunwoong; Gopi, Chandu V.V.M.; Kim, Hee-Je; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu

2017-01-01

Highlights: •We studied polymer nano-composite containing TiO 2 nano-particles as a catalyst. •Polymer nano-composite was applied for quantum dot-sensitized solar cells. •Polymer nano-composite catalyst was considerably improved with TiO 2 nano-particles. •Polymer nano-composite showed higher photovoltaic performance than conventional Au. -- Abstract: Polymer nano-composite composed of poly(3,4-ethylenedioxythiophene):poly (styrenesulfonate) and TiO 2 nano-particles was deposited on fluorine-doped tin oxide substrate and applied as an alternative to Au counter electrode of quantum dot-sensitized solar cell (QDSC). It became surface-richer with the increase in nano-particle amount so that catalytic reaction was increased by widened catalytic interface. Electrochemical impedance spectroscopy and cyclic voltammetry clearly demonstrated the enhancement of polymer nano-composite counter electrode. A QDSC based on polymer nano-composite counter electrode showed 0.56 V of V OC , 12.24 mA cm −2 of J SC , 0.57 of FF, and 3.87% of efficiency and this photovoltaic performance was higher than that of QDSC based on Au counter electrode (3.75%).

Fluorescent boronic acid terminated polymer grafted silica particles synthesized via click chemistry for affinity separation of saccharides

Energy Technology Data Exchange (ETDEWEB)

Xu, Zhifeng, E-mail: 897061147@qq.com; Deng, Peihong; Tang, Siping; Li, Junhua

2014-07-01

Boronic acids are important for effective separation of biological active cis-diols. For the purpose of constructing a new type of saccharide-sensitive material which can not only provide convenient separation but also improve the access of boronic acid to guest molecules, the fluorogenic boronic acid terminated, thermo-sensitive polymers (BA-polyNIPAm) were grafted to an alkyne modified silica gel through the exploitation of click chemistry. The BA-polyNIPAm grafted silica gel (BA-polyNIPAm-SG) was characterized by FT-IR, fluorescence spectra, fluorescence microscopy, elemental analysis (EA), thermal gravimetric analysis (TGA), scanning electron microscope (SEM) and so on. BA-polyNIPAm-SG displayed affinity binding ability for saccharides under physiological pH value and allowed saccharides to be conveniently separated from solution. The maximum binding capacities for fructose and glucose are 83.2 μmol/g and 70.4 μmol/g polymer, respectively. The intensity of fluorescence emission of BA-polyNIPAm-SG increased with the increasing of fructose concentration. The present study provides a new kind of composite material which contains moveable and flexible grippers for recognizing and binding guest molecules. - Highlights: • Fluorogenic boronic acid terminated polymers were conjugated to silica particle. • The prepared material can conveniently separate saccharides from solution. • The prepared material displays increased fluorescence emission upon binding fructose.

Fluorescent boronic acid terminated polymer grafted silica particles synthesized via click chemistry for affinity separation of saccharides

International Nuclear Information System (INIS)

Xu, Zhifeng; Deng, Peihong; Tang, Siping; Li, Junhua

2014-01-01

Boronic acids are important for effective separation of biological active cis-diols. For the purpose of constructing a new type of saccharide-sensitive material which can not only provide convenient separation but also improve the access of boronic acid to guest molecules, the fluorogenic boronic acid terminated, thermo-sensitive polymers (BA-polyNIPAm) were grafted to an alkyne modified silica gel through the exploitation of click chemistry. The BA-polyNIPAm grafted silica gel (BA-polyNIPAm-SG) was characterized by FT-IR, fluorescence spectra, fluorescence microscopy, elemental analysis (EA), thermal gravimetric analysis (TGA), scanning electron microscope (SEM) and so on. BA-polyNIPAm-SG displayed affinity binding ability for saccharides under physiological pH value and allowed saccharides to be conveniently separated from solution. The maximum binding capacities for fructose and glucose are 83.2 μmol/g and 70.4 μmol/g polymer, respectively. The intensity of fluorescence emission of BA-polyNIPAm-SG increased with the increasing of fructose concentration. The present study provides a new kind of composite material which contains moveable and flexible grippers for recognizing and binding guest molecules. - Highlights: • Fluorogenic boronic acid terminated polymers were conjugated to silica particle. • The prepared material can conveniently separate saccharides from solution. • The prepared material displays increased fluorescence emission upon binding fructose

Gas permeation through a polymer network

International Nuclear Information System (INIS)

Schmittmann, B; Gopalakrishnan, Manoj; Zia, R K P

2005-01-01

We study the diffusion of gas molecules through a two-dimensional network of polymers with the help of Monte Carlo simulations. The polymers are modelled as non-interacting random walks on the bonds of a two-dimensional square lattice, while the gas particles occupy the lattice cells. When a particle attempts to jump to a nearest-neighbour empty cell, it has to overcome an energy barrier which is determined by the number of polymer segments on the bond separating the two cells. We investigate the gas current J as a function of the mean segment density ρ, the polymer length l and the probability q m for hopping across m segments. Whereas J decreases monotonically with ρ for fixed l, its behaviour for fixed ρ and increasing ldepends strongly on q. For small, non-zero q, J appears to increase slowly with l. In contrast, for q = 0, it is dominated by the underlying percolation problem and can be non-monotonic. We provide heuristic arguments to put these interesting phenomena into context

Thermodynamics of swelling of latex particles with two monomers

NARCIS (Netherlands)

Maxwell, I.A.; Kurja, J.; van Doremaele, G.H.J.; German, A.L.

1992-01-01

The partitioning of 2 monomers between the latex particle, monomer droplet, and aq. phases of an emulsion polymer latex are measured at satn. swelling of the latex particle phase (corresponding to intervals I and II of an emulsion polymn.). The monomer (Me acrylate, Bu acrylate, styrene) and polymer

Synthesis of Monodisperse CdSe QDs using Controlled Growth Temperatures

International Nuclear Information System (INIS)

Noor Razinah Rahmat; Akrajas Ali Umar; Muhammad Yahya; Muhamad Mat Salleh; Mohammad Hafizuddin Jumali

2011-01-01

The effect of growth temperatures on size of CdSe quantum dots (QDs) has been investigated. CdSe QDs were synthesized using thermolysis of organometallics precursor route using wet chemical method. The growth temperature was varied from 260-310 degree Celsius with growth period fixed at 60 s. As the growth temperature increased, the monodispersed CdSe QDs with diameter in the range 3-7 nm were obtained. Both absorption and PL spectra of the QDs revealed a strong red-shift supporting the increment size of QDs with the rise of growth temperature. (author)

Segregation of chain ends to polymer melt surfaces and interfaces

International Nuclear Information System (INIS)

Zhao, W.; Zhao, X.; Rafailovich, M.H.; Sokolov, J.; Composto, R.J.; Smith, S.D.; Satkowski, M.; Russell, T.P.; Dozier, W.D.; Mansfield, T.

1993-01-01

The conformation of polymer chains in the melt near an impenetrable boundary has recently been studied by molecular dynamics and off-lattice Monte Carlo simulations. Both types of calculations show an enhancement of the chain end density within a distance of approximately two polymer segment lengths of the interface relative to the bulk. In the absence of preferential interactions between monomers and the interface, the segregation arises from minimizing the loss of conformational entropy near an impenetrable boundary; i.e., by positioning an end near the surface, only one unit rather than two is reflected. In order to obtain an experimental measure of this effect, monodisperse polystyrene (PS) chains of molecular weight 63 000 with short blocks of deuterated polystyrene (dPS) at each end were prepared. The block length was kept as short as possible, while yet producing sufficient neutron scattering contrast in order to minimize any preferential surface segregation due to isotopic effects. The synthesis was carried out via living anionic polymerization of a purified styrene monomer in cyclohexane at 60 C, utilizing sec-butyllithium as the initiator. The process was terminated using degassed methanol

Functional Hybrid Biomaterials based on Peptide-Polymer Conjugates for Nanomedicine

Science.gov (United States)

Shu, Jessica Yo

The focus of this dissertation is the design, synthesis and characterization of hybrid functional biomaterials based on peptide-polymer conjugates for nanomedicine. Generating synthetic materials with properties comparable to or superior than those found in nature has been a "holy grail" for the materials community. Man-made materials are still rather simplistic when compared to the chemical and structural complexity of a cell. Peptide-polymer conjugates have the potential to combine the advantages of the biological and synthetic worlds---that is they can combine the precise chemical structure and diverse functionality of biomolecules with the stability and processibility of synthetic polymers. As a new family of soft matter, they may lead to materials with novel properties that have yet to be realized with either of the components alone. In order for peptide-polymer conjugates to reach their full potential as useful materials, the structure and function of the peptide should be maintained upon polymer conjugation. The success in achieving desirable, functional assemblies relies on fundamentally understanding the interactions between each building block and delicately balancing and manipulating these interactions to achieve targeted assemblies without interfering with designed structures and functionalities. Such fundamental studies of peptide-polymer interactions were investigated as the nature of the polymer (hydrophilic vs. hydrophobic) and the site of its conjugation (end-conjugation vs. side-conjugation) were varied. The fundamental knowledge gained was then applied to the design of amphiphiles that self-assemble to form stable functional micelles. The micelles exhibited exceptional monodispersity and long-term stability, which is atypical of self-assembled systems. Thus such micelles based on amphiphilic peptide-polymer conjugates may meet many current demands in nanomedicine, in particular for drug delivery of hydrophobic anti-cancer therapeutics. Lastly

Numerical simulations of flows through fixed networks of monodispersed and bi-dispersed spheres, for moderate Reynolds numbers; Simulations numeriques d'ecoulements a travers des reseaux fixes de spheres monodisperses et bidisperses, pour des nombres de Reynolds moderes

Energy Technology Data Exchange (ETDEWEB)

Massol, A.

2004-02-15

The application of statistically averaged two-fluid models for the simulation of complex indus- trial two-phase flows requires the development of adequate models for the drag force exerted on the inclusions and the interfacial heat exchange. This task becomes problematic at high volume fractions of the dispersed phase. The quality of the simulation strongly depends upon the inter- facial exchange terms, starting with the steady drag force. For example, an accurate modelling of the drag force is therefore a crucial point to simulate the expansion of dense fluidized beds. Most models used to study the exchange terms between particles and fluids are based on the interaction between an isolated particle and a surrounding gas. Those models are clearly not adequate in cases where the volume fraction of particles increases and particle-particle interactions become important. Studying such cases is a complex task because of the multiple possible configurations. While the interaction between an isolated sphere and a gas depends only on the particle size and the slip velocity between gas and particles, the interaction between a cloud of particles and a gas depends on many more parameters: size and velocity distribution of particles, relative position of particles. Even if the particles keep relative fixed positions, there is an infinite number of combinations to construct such an array. The objective of the present work is to perform steady and unsteady simulations of the flow in regular arrays of fixed particles in order to analyze the influence of the size and distributions of spheres on drag force and heat transfer (the array of spheres can be either monodispersed, either bi-dispersed). Several authors have studied the drag exerted on the spheres, but only for low Reynolds numbers and/or solid volume fractions close to the packed limit. Moreover some discrepancies are observed between the different studies. On top of that, all existing studies are limited to steady flows

Lipid-peptide-polymer conjugates and nanoparticles thereof

Science.gov (United States)

Xu, Ting; Dong, He; Shu, Jessica

2015-06-02

The present invention provides a conjugate having a peptide with from about 10 to about 100 amino acids, wherein the peptide adopts a helical structure. The conjugate also includes a first polymer covalently linked to the peptide, and a hydrophobic moiety covalently linked to the N-terminus of the peptide, wherein the hydrophobic moiety comprises a second polymer or a lipid moiety. The present invention also provides helix bundles form by self-assembling the conjugates, and particles formed by self-assembling the helix bundles. Methods of preparing the helix bundles and particles are also provided.

Absorbency of Superabsorbent Polymers in Cementitious Environments

DEFF Research Database (Denmark)

Esteves, Luis Pedro; Jensen, Ole Mejlhede

2012-01-01

Optimal use of superabsorbent polymers (SAP) in cement-based materials relies on knowledge on how SAP absorbency is influenced by different physical and chemical parameters. These parameters include salt concentration in the pore fluid, temperature of the system and SAP particle size. The present...... work shows experimental results on this and presents a new technique to measure the swelling of SAP particles. This new technique is compared with existing techniques that have been recently proposed for the measurement of pore fluid absorption by superabsorbent polymers. It is seen...

Predictable Particle Engineering: Programming the Energy Level, Carrier Generation, and Conductivity of Core-Shell Particles.

Science.gov (United States)

Yuan, Conghui; Wu, Tong; Mao, Jie; Chen, Ting; Li, Yuntong; Li, Min; Xu, Yiting; Zeng, Birong; Luo, Weiang; Yu, Lingke; Zheng, Gaofeng; Dai, Lizong

2018-06-20

Core-shell structures are of particular interest in the development of advanced composite materials as they can efficiently bring different components together at nanoscale. The advantage of this structure greatly relies on the crucial design of both core and shell, thus achieving an intercomponent synergistic effect. In this report, we show that decorating semiconductor nanocrystals with a boronate polymer shell can easily achieve programmable core-shell interactions. Taking ZnO and anatase TiO 2 nanocrystals as inner core examples, the effective core-shell interactions can narrow the band gap of semiconductor nanocrystals, change the HOMO and LUMO levels of boronate polymer shell, and significantly improve the carrier density of core-shell particles. The hole mobility of core-shell particles can be improved by almost 9 orders of magnitude in comparison with net boronate polymer, while the conductivity of core-shell particles is at most 30-fold of nanocrystals. The particle engineering strategy is based on two driving forces: catechol-surface binding and B-N dative bonding and having a high ability to control and predict the shell thickness. Also, this approach is applicable to various inorganic nanoparticles with different components, sizes, and shapes.

Pair interactions in polyelectrolyte-nanoparticle systems: Influence of dielectric inhomogeneities and the partial dissociation of polymers and nanoparticles

International Nuclear Information System (INIS)

Pryamitsyn, Victor; Ganesan, Venkat

2015-01-01

We study the effective pair interactions between two charged spherical particles in polyelectrolyte solutions using polymer self-consistent field theory. In a recent study [V. Pryamitsyn and V. Ganesan, Macromolecules 47, 6095 (2015)], we considered a model in which the particles possess fixed charge density, the polymers contain a prespecified amount of dissociated charges and, the dielectric constant of the solution was assumed to be homogeneous in space and independent of the polymer concentration. In this article, we present results extending our earlier model to study situations in which either or both the particle and the polymers possess partially dissociable groups. Additionally, we also consider the case when the dielectric constant of the solution depends on the local concentration of the polymers and when the particle’s dielectric constant is lower than that of the solvent. For each case, we quantify the polymer-mediated interactions between the particles as a function of the polymer concentrations and the degree of dissociation of the polymer and particles. Consistent with the results of our previous study, we observe that the polymer-mediated interparticle interactions consist of a short-range attraction and a long-range repulsion. The partial dissociablity of the polymer and particles was seen to have a strong influence on the strength of the repulsive portion of the interactions. Rendering the dielectric permittivity to be inhomogeneous has an even stronger effect on the repulsive interactions and results in changes to the qualitative nature of interactions in some parametric ranges

Polymer nanocomposite particles of S-nitrosoglutathione: A suitable formulation for protection and sustained oral delivery.

Science.gov (United States)

Wu, Wen; Gaucher, Caroline; Fries, Isabelle; Hu, Xian-Ming; Maincent, Philippe; Sapin-Minet, Anne

2015-11-10

S-nitrosoglutathione (GSNO) is a nitric oxide (NO) donor with therapeutic potential for cardiovascular disease treatment. Chronic oral treatment with GSNO is limited by high drug sensitivity to the environment and limited oral bioavailability, requiring the development of delivery systems able to sustain NO release. The present work describes new platforms based on polymer nanocomposite particles for the delivery of GSNO. Five types of optimized nanocomposite particles have been developed (three based on chitosan, two based on alginate sodium). Those nanocomposite particles encapsulate GSNO with high efficiency from 64% to 70% and an average size of 13 to 61 μm compatible with oral delivery. Sustained release of GSNO in vitro was achieved. Indeed, chitosan nanocomposites discharged their payload within 24h; whereas alginate nanocomposites released GSNO more slowly (10% of GSNO was still remaining in the dosage form after 24h). Their cytocompatibility toward intestinal Caco-2 cells (MTT assay) was acceptable (IC50: 6.07 ± 0.07-9.46 ± 0.08 mg/mL), demonstrating their suitability as oral delivery systems for GSNO. These delivery systems presented efficient GSNO loading and sustained release as well as cytocompatibility, showing their promise as a means of improving the oral bioavailability of GSNO and as a potential new treatment. Copyright © 2015 Elsevier B.V. All rights reserved.

Facile Deposition of Ultrafine Silver Particles on Silicon Surface Not Submerged in Precursor Solutions for Applications in Antireflective Layer

Directory of Open Access Journals (Sweden)

Bing Jiang

2014-01-01

Full Text Available Using a facile deposition method, the ultrafine silver particles are successfully deposited on the Si surface that is not submerged in precursor solutions. The ultrafine silver particles have many advantages, such as quasiround shape, uniformity in size, monodisperse distribution, and reduction of agglomeration. The internal physical procedure in the deposition is also investigated. The results show that there are more particles on the rough Si surface due to the wetting effect of solid-liquid interface. The higher concentration of ethanol solvent can induce the increase of quantity and size of particles on Si surface not in solutions. The ultrafine particles can be used to prepare porous Si antireflective layer in solar cell applications.

Engineering of budesonide-loaded lipid-polymer hybrid nanoparticles using a quality-by-design approach.

Science.gov (United States)

Leng, Donglei; Thanki, Kaushik; Fattal, Elias; Foged, Camilla; Yang, Mingshi

2017-08-25

Chronic obstructive pulmonary disease (COPD) is a complex disease, characterized by persistent airflow limitation and chronic inflammation. The purpose of this study was to design lipid-polymer hybrid nanoparticles (LPNs) loaded with the corticosteroid, budesonide, which could potentially be combined with small interfering RNA (siRNA) for COPD management. Here, we prepared LPNs based on the biodegradable polymer poly(dl-lactic-co-glycolic acid) (PLGA) and the cationic lipid dioleyltrimethylammonium propane (DOTAP) using a double emulsion solvent evaporation method. A quality-by-design (QbD) approach was adopted to define the optimal formulation parameters. The quality target product profile (QTPP) of the LPNs was identified based on risk assessment. Two critical formulation parameters (CFPs) were identified, including the theoretical budesonide loading and the theoretical DOTAP loading. The CFPs were linked to critical quality attributes (CQAs), which included the intensity-based hydrodynamic particle diameter (z-average), the polydispersity index (PDI), the zeta-potential, the budesonide encapsulation efficiency, the actual budesonide loading and the DOTAP encapsulation efficiency. A response surface methodology (RSM) was applied for the experimental design to evaluate the influence of the CFPs on the CQAs, and to identify the optimal operation space (OOS). All nanoparticle dispersions displayed monodisperse size distributions (PDIPLGA increases when increasing the initial amount of budesonide. The OOS was modeled by applying the QTPP. The OOS had a budesonide encapsulation efficiency higher than 30%, a budesonide loading above 15μg budesonide/mg PLGA, a zeta-potential higher than 35mV and a DOTAP encapsulation efficiency above 50%. This study shows the importance of systematic formulation design for understanding the effect of formulation parameters on the characteristics of LPNs, eventually resulting in the identification of an OOS. Copyright © 2017 Elsevier B

Composition inversion in mixtures of binary colloids and polymer

Science.gov (United States)

Zhang, Isla; Pinchaipat, Rattachai; Wilding, Nigel B.; Faers, Malcolm A.; Bartlett, Paul; Evans, Robert; Royall, C. Patrick

2018-05-01

Understanding the phase behaviour of mixtures continues to pose challenges, even for systems that might be considered "simple." Here, we consider a very simple mixture of two colloidal and one non-adsorbing polymer species, which can be simplified even further to a size-asymmetrical binary mixture, in which the effective colloid-colloid interactions depend on the polymer concentration. We show that this basic system exhibits surprisingly rich phase behaviour. In particular, we enquire whether such a system features only a liquid-vapor phase separation (as in one-component colloid-polymer mixtures) or whether, additionally, liquid-liquid demixing of two colloidal phases can occur. Particle-resolved experiments show demixing-like behaviour, but when combined with bespoke Monte Carlo simulations, this proves illusory, and we reveal that only a single liquid-vapor transition occurs. Progressive migration of the small particles to the liquid phase as the polymer concentration increases gives rise to composition inversion—a maximum in the large particle concentration in the liquid phase. Close to criticality, the density fluctuations are found to be dominated by the larger colloids.

In-site synthesis of monodisperse, oleylamine-capped Ag nanoparticles through microemulsion approach

Science.gov (United States)

Chen, Shun; Ju, Yanyun; Guo, Yi; Xiong, Chuanxi; Dong, Lijie

2017-03-01

Ag NPs were in-site synthesized through microemulsion method by reducing silver acetate with oleylamine-mediated at 70 °C with highly monodisperse and narrow size from 10 to 20 nm. The synthesis of Ag NPs was aided by oleylamine and the role of oleylamine was researched. This in-site synthesis approach to Ag NPs was reproducibility and high yield more than 80% with stable store about 6 months.

The influence of particle size on intermediate and final stages of molybdenum sintering

International Nuclear Information System (INIS)

Uskokovic, D.; Novakovic, B.; Petrovic, V.; Ristic, M.M.

1982-01-01

The influence of initial particle size on kinetics of molybdenum sintering was investigated. Three fractions of monodispersed molybdenum powder (2, 5 and 10 μm) were used as well as a polydispersed powder with mean particle size of 12 μm. Decrease in particle size accelerates to a great extent densification and grain growth processes. During sintering of 10 μm powder and to a smaller extent in the case of polydispersed powder, Zeners's relation was confirmed. Quantitative equations for the intermediate sintering stages could not be fitted to the investigated particulate systems, even though the grain growth process could be described by cubic law and though the volume diffusion coefficient and the surface energy were known with great reliability. (Auth.)

Can natural polymers assist in delivering insulin orally?

Science.gov (United States)

Nur, Mokhamad; Vasiljevic, Todor

2017-10-01

Diabetes mellitus is one of the most grave and lethal non communicable diseases. Insulin is normally used to medicate diabetes. Due to bioavailability issues, the most regular route of administration is through injection, which may pose compliance problems to treatment. The oral administration thus appears as a suitable alternative, but with several important problems. Low stability of insulin in the gastrointestinal tract and low intestinal permeation are some of the issues. Encapsulation of insulin into polymer-based particles emerges as a plausible strategy. Different encapsulation approaches and polymers have been used in this regard. Polymers with different characteristics from natural or synthetic origin have been assessed to attain this goal, with natural polymers being preferable. Natural polymers studied so far include chitosan, alginate, carrageenan, starch, pectin, casein, tragacanth, dextran, carrageenan, gelatine and cyclodextrin. While some promising knowledge and results have been gained, a polymeric-based particle system to deliver insulin orally has not been introduced onto the market yet. In this review, effectiveness of different natural polymer materials developed so far along with fabrication techniques are evaluated. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis of Environmentally Responsive Polymers by Atom Transfer Radical Polymerization: Generation of Reversible Hydrophilic and Hydrophobic Surfaces

Directory of Open Access Journals (Sweden)

Vikas Mittal

2010-05-01

Full Text Available Environmentally responsive poly(N-isopropylacrylamide brushes were grafted from the surface of polymer particles or flat surfaces in order to generate reversible hydrophilic and hydrophobic surfaces. The use of atom transfer radical polymerization was demonstrated for the grafting of polymer brushes as it allows efficient control on the amount of grafted polymer. The polymer particles were generated with or without surfactant in the emulsion polymerization and their surface could be modified with the atom transfer radical polymerization (ATRP initiator. The uniform functionalization of the surface with ATRP initiator was responsible for the uniform grafting of polymer brushes. The grafted brushes responded reversibly with changes in temperature indicating that the reversible responsive behavior could be translated to the particle surfaces. The particles were observed to adsorb and desorb protein and virus molecules by changing the temperatures below or higher than 32 °C. The initiator functionalized particles could also be adsorbed on the flat surfaces. The adsorption process also required optimization of the heat treatment conditions to form a uniform layer of the particles on the substrate. The grafted polymer brushes also responded to the changes in temperatures similar to the spherical particles studied through water droplets placed on the flat substrates.

Core-shell particles at fluid interfaces

NARCIS (Netherlands)

Buchcic, C.

2016-01-01

There is a growing interest in the use of particles as stabilizers for foams and emulsions. Applying hard particles for stabilization of fluid interface is referred to as Pickering stabilization. By using hard particles instead of surfactants and polymers, fluid interfaces can be effectively

Multilayer Electroactive Polymer Composite Material

Science.gov (United States)

Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Park, Cheol (Inventor); Draughon, Gregory K. (Inventor); Ounaies, Zoubeida (Inventor)

2011-01-01

An electroactive material comprises multiple layers of electroactive composite with each layer having unique dielectric, electrical and mechanical properties that define an electromechanical operation thereof when affected by an external stimulus. For example, each layer can be (i) a 2-phase composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation, or (ii) a 3-phase composite having the elements of the 2-phase composite and further including a third component of micro-sized to nano-sized particles of an electroactive ceramic incorporated in the polymer matrix.

Biocompatible Amphiphilic Hydrogel-Solid Dimer Particles as Colloidal Surfactants.

Science.gov (United States)

Chen, Dong; Amstad, Esther; Zhao, Chun-Xia; Cai, Liheng; Fan, Jing; Chen, Qiushui; Hai, Mingtan; Koehler, Stephan; Zhang, Huidan; Liang, Fuxin; Yang, Zhenzhong; Weitz, David A

2017-12-26

Emulsions of two immiscible liquids can slowly coalesce over time when stabilized by surfactant molecules. Pickering emulsions stabilized by colloidal particles can be much more stable. Here, we fabricate biocompatible amphiphilic dimer particles using a hydrogel, a strongly hydrophilic material, and achieve large contrast in the wetting properties of the two bulbs, resulting in enhanced stabilization of emulsions. We generate monodisperse single emulsions of alginate and shellac solution in oil using a flow-focusing microfluidics device. Shellac precipitates from water and forms a solid bulb at the periphery of the droplet when the emulsion is exposed to acid. Molecular interactions result in amphiphilic dimer particles that consist of two joined bulbs: one hydrogel bulb of alginate in water and the other hydrophobic bulb of shellac. Alginate in the hydrogel compartment can be cross-linked using calcium cations to obtain stable particles. Analogous to surfactant molecules at the interface, the resultant amphiphilic particles stand at the water/oil interface with the hydrogel bulb submerged in water and the hydrophobic bulb in oil and are thus able to stabilize both water-in-oil and oil-in-water emulsions, making these amphiphilic hydrogel-solid particles ideal colloidal surfactants for various applications.

Spheronization process particle kinematics determined by discrete element simulations and particle image velocimentry measurements.

Science.gov (United States)

Koester, Martin; García, R Edwin; Thommes, Markus

2014-12-30

Spheronization is an important pharmaceutical manufacturing technique to produce spherical agglomerates of 0.5-2mm diameter. These pellets have a narrow size distribution and a spherical shape. During the spheronization process, the extruded cylindrical strands break in short cylinders and evolve from a cylindrical to a spherical state by deformation and attrition/agglomeration mechanisms. Using the discrete element method, an integrated modeling-experimental framework is presented, that captures the particle motion during the spheronization process. Simulations were directly compared and validated against particle image velocimetry (PIV) experiments with monodisperse spherical and dry γ-Al2O3 particles. demonstrate a characteristic torus like flow pattern, with particle velocities about three times slower than the rotation speed of the friction plate. Five characteristic zones controlling the spheronization process are identified: Zone I, where particles undergo shear forces that favors attrition and contributes material to the agglomeration process; Zone II, where the static wall contributes to the mass exchange between particles; Zone III, where gravitational forces combined with particle motion induce particles to collide with the moving plate and re-enter Zone I; Zone IV, where a subpopulation of particles are ejected into the air when in contact with the friction plate structure; and Zone V where the low poloidal velocity favors a stagnant particle population and is entirely controlled by the batch size. These new insights in to the particle motion are leading to deeper process understanding, e.g., the effect of load and rotation speed to the pellet formation kinetics. This could be beneficial for the optimization of a manufacturing process as well as for the development of new formulations. Copyright © 2014 Elsevier B.V. All rights reserved.

Structural state diagram of concentrated suspensions of jammed soft particles in oscillatory shear flow

Science.gov (United States)

Khabaz, Fardin; Cloitre, Michel; Bonnecaze, Roger T.

2018-03-01

In a recent study [Khabaz et al., Phys. Rev. Fluids 2, 093301 (2017), 10.1103/PhysRevFluids.2.093301], we showed that jammed soft particle glasses (SPGs) crystallize and order in steady shear flow. Here we investigate the rheology and microstructures of these suspensions in oscillatory shear flow using particle-dynamics simulations. The microstructures in both types of flows are similar, but their evolutions are very different. In both cases the monodisperse and polydisperse suspensions form crystalline and layered structures, respectively, at high shear rates. The crystals obtained in the oscillatory shear flow show fewer defects compared to those in the steady shear. SPGs remain glassy for maximum oscillatory strains less than about the yield strain of the material. For maximum strains greater than the yield strain, microstructural and rheological transitions occur for SPGs. Polydisperse SPGs rearrange into a layered structure parallel to the flow-vorticity plane for sufficiently high maximum shear rates and maximum strains about 10 times greater than the yield strain. Monodisperse suspensions form a face-centered cubic (FCC) structure when the maximum shear rate is low and hexagonal close-packed (HCP) structure when the maximum shear rate is high. In steady shear, the transition from a glassy state to a layered one for polydisperse suspensions included a significant induction strain before the transformation. In oscillatory shear, the transformation begins to occur immediately and with different microstructural changes. A state diagram for suspensions in large amplitude oscillatory shear flow is found to be in close but not exact agreement with the state diagram for steady shear flow. For more modest amplitudes of around one to five times the yield strain, there is a transition from a glassy structure to FCC and HCP crystals, at low and high frequencies, respectively, for monodisperse suspensions. At moderate frequencies, the transition is from glassy to HCP via

Infinite Coordination Polymer Nano- and Micro-Particles

Science.gov (United States)

2015-06-12

attachment (Figure 1). Particles were synthesized by combining DABA-bis-HP-N3 and ferric nitrate in dilute NaOH. The crude particles were purified by...cervical cancer cells using dye-labeled DNA (Figure 2). The ICP-DNA particles were found to cross cell membranes with efficiency very similar to the...deliver their genetic cargo to the cell and effect expression of a known cancer -related mRNA transcript in vitro. SKOV-3 ovarian cancer cells were chosen

Thermal spraying of polyethylene-based polymers: Processing and characterization

Science.gov (United States)

Otterson, David Mark

This research explores the development of a flame-spray process map as it relates to polymers. This work provides a more complete understanding of the thermal history of the coating material from injection, to deposition and finally to cooling. This was accomplished through precise control of the processing conditions during deposition. Mass flow meters were used to monitor air and fuel flows as they were systematically changed, while temperatures were simultaneously monitored along the length of the flame. A process model was then implemented that incorporated this information along with measured particle velocities, particle size distribution, the polymer's melting temperature and its enthalpy of melting. This computational model was then used to develop a process map that described particle softening, melting and decomposition phenomena as a function of particle size and standoff distance. It demonstrated that changes in particle size caused significant variations in particle states achieved in-flight. A series of experiments were used to determine the range of spray parameters within which a cohesive coating without visible signs of degradation could be sprayed. These results provided additional information that complimented the computational processing map. The boundaries established by these results were the basis for a Statistical Design of Experiments that tested the effects that subtle processing changes had on coating properties. A series of processing maps were developed that combined the computational and the experimental results to describe the manner in which processing parameters interact to determine the degree of melting, polymer degradation and coating porosity. Strong interactions between standoff distance and traverse rate can cause the polymer to degrade and form pores in the coating. A clear picture of the manner in which particle size and standoff distance interact to determine particle melting was provided by combining the computational

Biomimetic block copolymer particles with gated nanopores and ultrahigh protein sorption capacity

KAUST Repository

Yu, Haizhou

2014-06-17

The design of micro-or nanoparticles that can encapsulate sensitive molecules such as drugs, hormones, proteins or peptides is of increasing importance for applications in biotechnology and medicine. Examples are micelles, liposomes and vesicles. The tiny and, in most cases, hollow spheres are used as vehicles for transport and controlled administration of pharmaceutical drugs or nutrients. Here we report a simple strategy to fabricate microspheres by block copolymer self-assembly. The microsphere particles have monodispersed nanopores that can act as pH-responsive gates. They contain a highly porous internal structure, which is analogous to the Schwarz P structure. The internal porosity of the particles contributes to their high sorption capacity and sustained release behaviour. We successfully separated similarly sized proteins using these particles. The ease of particle fabrication by macrophase separation and self-assembly, and the robustness of the particles makes them ideal for sorption, separation, transport and sustained delivery of pharmaceutical substances. © 2014 Macmillan Publishers Limited.