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Fabrication and Defect Designs on DNA Linked 2D Colloidal Photonic Crystals Using a Nd:YAG Pulsed Laser

MRS Online Proceedings Library 2006年第1期901卷 1-6页

作者： Ramazan Asmatulu Sejong Kim Robin Bright Phillip Yu Fotios Papadimitrakopoulos Harris Marcus Department of Materials Science and Engineering Institute of Materials Science University of Connecticut Storrs USA Department of Chemistry Nanomaterials Optoelectronics Laboratory Polymer Program Institute of Materials Science University of Connecticut Storrs USA

Controlled defects were created on DNA linked 2-D colloidal photonic crystals using a Nd:YAG pulsed laser. The 2-D photonic crystals were self-assembled using 1.8 μm polystyrene (PS) microspheres on functionalized glass substrates. To synthesize the hexagonal close packed crystalline samples, both substrate and particles attached single-strand DNA, sequence A on the substrate and sequence B on the particles. The DNA was hybridized using the DNA linker with complementary single-strand A’B’ that anchored the particles to the substrate during self-assembly. The 532 nm second harmonic wavelength beam of the pulsed Nd:YAG laser (1064 nm) with a pulse width of 10 ns was used for the removal of individual colloidal particles from the self assembled photonic crystals. In the present tests, the diameter of the laser beam was optically reduced from 7 mm to about 1.8 μm. Controlled line defects and geometrical shapes (e.g., hexagonal and triangle) were created in the 2D arrays in an aqueous medium.

关键词： colloid crystal laser

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Preparation and characterization of polymeric capsules containing functional additives

Preparation and characterization of polymeric capsules conta...

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Society of Plastics Engineers Annual Technical Conference 2006, ANTEC 2006

作者： Park, K. Feng, W. Kim, K. Xanthos, M. Materials Science and Engineering Program New Jersey Institute of Technology Newark NJ 07102 Otto H. York Department of Chemical Engineering New Jersey Institute of Technology Newark NJ 07102 Polymer Processing Institute New Jersey Institute of Technology Newark NJ 07102 Seoul National University Korea Republic of

In attempts to develop novel functional additives for thermoplastic and thermoset polymer coatings, various sizes of microcapsules containing a silicone fluid which could facilitate the release of the coating from a metallic substrate were prepared by in-situ polymerization. Fill content, size of capsules, wall-thickness, and surface morphology were observed by TGA, TEM, SEM, EDX, optical and NMR microscopy. The capsules were dispersed in polymeric coatings and the release of their content through mechanical means was followed microscopically.

关键词： Organic polymers

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Solvent mediated assembly of nanoparticles confined in mesoporous alumina

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Physical Review B 2006年第12期73卷 125412-125412页

作者： Kyle J. Alvine Diego Pontoni Oleg G. Shpyrko Peter S. Pershan David J. Cookson Kyusoon Shin Thomas P. Russell Markus Brunnbauer Francesco Stellacci Oleg Gang Division of Engineering and Applied Sciences Harvard University Cambridge Massachusetts 02138 USA Center for Nanoscale Materials Argonne National Laboratory Argonne Illinois 60439 USA Department of Physics Harvard University Cambridge Massachusetts 02138 USA Australian Synchrotron Research Program Building 434 Argonne National Laboratory Argonne Illinois 60439 USA Department of Polymer Science and Engineering University of Massachusetts Amherst Massachusetts 01003 USA Department of Materials Science and Engineering Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Center for Functional Nanomaterials Brookhaven National Lab Upton New York 11973 USA

The controlled self-assembly of thiol stabilized gold nanocrystals in a mediating solvent and confined within mesoporous alumina was probed in situ with small angle x-ray scattering. The evolution of the self-assembly process was controlled reversibly via regulated changes in the amount of solvent condensed from an undersaturated vapor. Analysis indicated that the nanoparticles self-assembled into cylindrical monolayers within the porous template. Nanoparticle nearest-neighbor separation within the monolayer increased and the ordering decreased with the controlled addition of solvent. The process was reversible with the removal of solvent. Isotropic clusters of nanoparticles were also observed to form temporarily during desorption of the liquid solvent and disappeared upon complete removal of liquid. Measurements of the absorption and desorption of the solvent showed strong hysteresis upon thermal cycling. In addition, the capillary filling transition for the solvent in the nanoparticle-doped pores was shifted to larger chemical potential, relative to the liquid/vapor coexistence, by a factor of 4 as compared to the expected value for the same system without nanoparticles.

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Vapor permeation and pervaporation of aqueous 2-propanol solutions through the Torlon© poly(amide imide) membrane (vol 40, pg 2697, 2005)

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SEPARATION science AND TECHNOLOGY 2005年第16期40卷 3419-3419页

作者： Higuchi, A Department of Polymer Science and Engineering Kyoto Institute of Technology Matsugasaki Kyoto Japan Institute of Chemical Process and Environmental Technology National Research Council of Canada Ottawa Ont. Canada Department of Polymer Science and Engineering Kyoto Institute of Technology Matsugasaki Kyoto 606-8585 Japan

In the present study, vapor permeation and pervaporation of aqueous 2propanol mixtures were investigated using Torlon poly(amide imide) as a membrane material. Torlon membranes preferentially permeated H 2 O from aqueous 2PrOH mixtures both by vapor permeation and pervaporation. Diffusion experiments led to the conclusion that both solubility selectivity and diffusivity selectivity showed a preference for H 2 O. Solubility selectivity is by far the dominant factor governing permselectivity, and as a result, Torlon membranes showed permselectivity toward water in vapor permeation and pervaporation. The present study showed that Torlon poly(amide imide) is a membrane material potentially applicable to the dehydration of water miscible organics.

关键词： Diffusion coefficients Diffusivity selectivity Permselectivity Pervaporation Solubility selectivity Torlon Vapor permeation

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Functionalized three-arm poly(ε-caprolactone) maleic acid microspheres for controlled protein release

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American Journal of Drug Delivery 2005年第4期3卷 253-267页

作者： Wu, Da-Qing Zhang, Xiang-Zheng Chu, Chih-Chang Fiber and Polymer Science Program Department of Textiles and Apparel and Biomedical Engineering Program Cornell University Ithaca NY United States Fiber and Polymer Science Program Department of Textiles and Apparel and Biomedical Engineering Program Cornell University Ithaca NY 14853-4401 United States

Introduction: The objective of this work was to fabricate a novel class of protein carriers from double-bond-functionalized multiarm poly(ε- caprolactone) maleic acid (PGCLM) microspheres and to examine protein sustained-release profiles in vitro over a period of a few months. Methods: The double-emulsion technique was used to formulate terminal functionalized three-arm PGCLM microspheres having three different types of functional groups (-OH, -COOH, and -C = C-), and one of the functional groups (>C = < bonds) was used to formulate surface-crosslinked microspheres (NPGCLM). Ovalbumin (OVA) was used as a model protein for examining its release profiles from PGCLM and NPGCLM microspheres in 0.1M phosphate-buffered saline (PBS) at 37°C. These microspheres were also characterized in terms of their morphology, size distribution, and stability. Results: The mean size of fabricated microspheres ranged from 21.9μm to 51.1μm. An OVA protein was successfully encapsulated into these biodegradable PGCLM microspheres with loading efficiency ranging from 34.2% to 46% (w/w), depending on the ratio of PGCLM to polyvinyl alcohol (PVA) stabilizer. Depending on the polymer to PVA stabilizer ratio, the cumulative OVA release % (w/w) in 0.1M PBS at 37°C ranged from 30% to 40% within 50 days. We further demonstrated the availability of the functional >C = C< bonds on the surface of PGCLM microspheres, which we expect could be used for either covalent binding of bioactive agents or imparting different chemical characteristics onto the surface of the microspheres for broadening of their applications. Discussion/Conclusion: A method for the preparation of biodegradable microspheres from water/oil emulsion of multiarm and functionalized poly(ε-caprolactone) [PGCL, PGCLM, and NPGCLM] was reported as a potential means of developing injectable therapeutic formulations for drugs. The most unique aspect of these biodegradable microspheres is the availability of two functional groups (>C = C< bon

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Strength distributions of sintered hydroxyapatite nanoparticles

Strength distributions of sintered hydroxyapatite nanopartic...

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11th International Conference on Fracture 2005, ICF11

作者： Kothapalli, Chandrasekhar Shaw, Montgomery T. Wei, M. Department of Materials Science and Engineering Institute of Materials Science University of Connecticut United States Department of Chemical Engineering and Polymer Program Institute of Materials Science University of Connecticut United States

ISBN: (纸本)9781617820632

In the past two decades, calcium phosphates, and especially hydroxyapatite (HA), have been used as bone substitutes, and the mechanical strength is one of the most important properties in this application. The flexural strength of an HA object depends on the nature of the HA powder, specimen preparation, flex test geometry and experimental conditions. HA was prepared by two methods, namely: wet and hydrothermal. The fundamental difference between these methods lies in the method of mixing the reactants and the reaction temperature. The obtained powders were pressed into pellets at 150 MPa and tested for flexural strength using a ring-on-disc method. The two-parameter Weibull and normal distributions were used to characterize the observed flexural strengths. Results were correlated with scanning microscope observations of fracture surfaces of the polished broken discs. The two-parameter Weibull distribution was found to be superior for the samples made with HA from the hydrothermal method. For the samples from the wet method, the normal distribution was equally suitable. The reason for this difference was sought by examining the discs for surface flaws.

关键词： Bending strength

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Tailor‐Made Onionlike Stereocomplex Crystals in Incompatible, Enantiomeric, Polylactide‐Containing Block Copolymer Blends†

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Angewandte Chemie 2006年第44期118卷

作者： Lu Sun Lei Zhu Lixia Rong Benjamin S. Hsiao Polymer Program Institute of Materials Science and Department of Chemical Materials and Biomolecular Engineering University of Connecticut Storrs CT 06269‐3136 USA Fax: (+1) 860‐486‐4745 http://www.ims.uconn.edu/∼lzhu Department of Chemistry State University of New York at Stony Brook Stony Brook NY 11794‐3400 USA

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Preparation of DNA hybrid polyethersulfone microspheres for endocrine disrupter removal

Preparation of DNA hybrid polyethersulfone microspheres for ...

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作者： Zhao, Changsheng Yang, Kaiguang Wen, Xian Li, Fan Zheng, Xiangben Nishi, Norio Department of Biomedical Polymer and Artificial Organs College of Polymer Science and Engineering Sichuan University Chengdu 610065 China Division of Bioscience Graduate School of Environmental Earth Science Hokkaido University Kita-ku Sapporo 060-0810 Japan

In this paper, DNA hybrid polyethersulfone (PES) microspheres, including DNA-loaded porous particles and DNA-encapsulated hollow particles, are fabricated using a liquid-liquid phase separation method based on precipitation technique;the microspheres are then used for the removal of poisonous organic chemicals and endocrine disrupters. With the increase of the DNA amount incorporated into the spheres, the removal ratios increased both for the poisonous organic chemicals and endocrine disrupters. The particles without DNA also remove and accumulate poisonous organic chemicals due to the high porosity of the spheres. The results suggested that DNA hybrid PES particles could be prepared by a liquid-liquid phase separation method, and have potential to serve as a useful functional biomaterial for medical, engineering, and environmental application.

关键词： Microspheres

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Crystallization of POSS in a PEG-based multiblock polyurethane: Toward a hybrid hydrogel

Crystallization of POSS in a PEG-based multiblock polyuretha...

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2004 Materials Research Society Fall Meeting

作者： Wu, Jian Ge, Qing Burke, Kelly A. Mather, Patrick T. Polymer Program Institute of Materials Science University of Connecticut Storrs CT 06269-3136 Department of Macromolecular Science and Engineering Case Western Reserve University Cleveland OH 44106

Building upon earlier success in forming materials with crystalline ordering of POSS via the telechelic architecture with POSS end-capping polyethylene glycols, here we report similar ordering in PEG-POSS thermoplastic polyurethane applicable to a novel hybrid hydrogel. Thus, a unique series of hybrid thermoplastic polyurethanes (TPUs) were synthesized using poly(ethylene glycol) (PEG) as soft segment and incorporating an isobutyl-functionalized POSS diol (TMP POSS diol) in the hard segment. The molecular weight of PEG was systematically varied to include 10: 20, and 35 kDa while the mole ratio of PEG to POSS diol (as chain extender) was chosen as 8:1. The diisocyanate employed for TPU polymerization was 4,4'methylenebis(phenyl-isocyanate) (MDI). Wide-angle X-ray diffraction (WAXD) studies revealed that both the hydrophilic soft segments (PEG) and hydrophobic hard segments (POSS) can form crystalline structures driven by micro-phase separation, itself due to thermodynamic incompatibility. Differential scanning calorimetry (DSC) and rheological studies revealed that thermal history is important in controlling the crystallization of a POSS-rich nanophase. Increasing the cooling rate monotonically decreases the crystallinity of POSS-rich phase and results in a decrease in the ultimate dynamic storage modulus following POSS crystallization and an increase of the loss angle for temperatures above Tm of PEG and below Tm of POSS. We conclude that both composition and thermal history are key factors in determing the internal network built by the POSS nanophase, which will have a significant influence on the properties of the resulting hybrid hydrogels now being studied. © 2005 Materials Research Society.

关键词： Crystallization

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Effect of electric field on alignment behavior and conductivity of composite membranes

Effect of electric field on alignment behavior and conductiv...

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Society of Plastics Engineers Annual Technical Conference 2005, ANTEC 2005

作者： Boob, Smita B. Shaw, Montgomery T. Polymer Program Institute of Materials Science University of Connecticut Storrs CT 06269 United States Department of Chemical Engineering Institute of Materials Science University of Connecticut Storrs CT 06269 United States

Composite membranes of sulfonated crosslinked polystyrene particles have been made by aligning the particles under an electric field in a crosslinked poly(dimethyl siloxane) matrix following a procedure described by Oren et al. (2004). The purpose of this work, however, was to investigate the effects of electric field amplitude and frequency on alignment behavior. As expected, the particles aligned only by application of a certain minimum electric field for a given frequency. Impedance measurements indicated that the unaligned membranes showed capacitive behavior up to 8 wt % particles, which transformed to conductive behavior on alignment.

关键词： polymeric membranes

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