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Mechanical Robustness (mechanical + robustness)
Selected AbstractsFormation of Thick Porous Anodic Alumina Films and Nanowire Arrays on Silicon Wafers and Glass,ADVANCED FUNCTIONAL MATERIALS, Issue 8 2003O. Rabin Abstract A method for the fabrication of thick films of porous anodic alumina on rigid substrates is described. The anodic alumina film was generated by the anodization of an aluminum film evaporated on the substrate. The morphology of the barrier layer between the porous film and the substrate was different from that of anodic films grown on aluminum substrates. The removal of the barrier layer and the electrochemical growth of nanowires within the ordered pores were accomplished without the need to remove the anodic film from the substrate. We fabricated porous anodic alumina samples over large areas (up to 70 cm2), and deposited in them nanowire arrays of various materials. Long nanowires were obtained with lengths of at least 9 ,m and aspect ratios as high as 300. Due to their mechanical robustness and the built-in contact between the conducting substrate and the nanowires, the structures were useful for electrical transport measurements on the arrays. The method was also demonstrated on patterned and non-planar substrates, further expanding the range of applications of these porous alumina and nanowire assemblies. [source] Conducting Nanocomposite Polymer Foams from Ice-Crystal-Templated Assembly of Mixtures of ColloidsADVANCED MATERIALS, Issue 28 2009Catheline A. L. Colard Fabrication of conducting nanocomposite- reinforced soft polymer foams is demonstrated. These multicomponent cellular materials are built from a mixture of colloids dispersed in water by freeze,drying, thereby using ice crystals as template for the porous structure. An excluded-volume effect armors the "soft"-polymer cell walls with "hard" nanoparticles, thereby enhancing the mechanical robustness of the foams. [source] Monolithic poly(1,2-bis(p -vinylphenyl)ethane) capillary columns for simultaneous separation of low- and high-molecular-weight compoundsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 15-16 2009Andreas Greiderer Abstract Monolithic poly(1,2-bis(p -vinylphenyl)ethane (BVPE)) capillary columns were prepared by thermally initiated free radical polymerisation of 1,2-bis(p -vinylphenyl)ethane in the presence of inert diluents (porogens) and ,,,,-azoisobutyronitrile (AIBN) as initiator. Polymerisations were accomplished in 200 ,m ID fused silica capillaries at 65°C and for 60 min. Mercury intrusion porosimetry measurements of the polymeric RP support showed a broad bimodal pore-size-distribution of mesopores and small macropores in the range of 5,400 nm and flow-channels in the ,m range. N2 -adsorption (BET) analysis resulted in a tremendous enhancement of surface area (101 m2/g) of BVPE stationary phases compared to typical organic monoliths (,20 m2/g), indicating the presence of a considerable amount of mesopores. Consequently, the adequate proportion of both meso- and (small) macropores allowed the rapid and high-resolution separation of low-molecular-weight compounds as well as biomolecules on the same monolithic support. At the same time, the high fraction of flow-channels provided enhanced column permeability. The chromatographic performance of poly(1,2-bis(p -vinylphenyl)ethane) capillary columns for the separation of biomolecules (proteins, oligonucleotides) and small molecules (alkyl benzenes, phenols, phenons) are demonstrated in this article. Additionally, pressure drop versus flow rate measurements of novel poly(1,2-bis(p -vinylphenyl)ethane) capillary columns confirmed high mechanical robustness, low swelling in organic solvents and high permeability. Due to the simplicity of monolith fabrication, comprehensive studies of the retention and separation behaviour of monolithic BVPE columns resulted in high run-to-run and batch-to-batch reproducibilities. All these attributes prove the excellent applicability of monolithic poly(1,2-bis(p -vinylphenyl)ethane) capillary columns for ,-HPLC towards a huge range of analytes of different chemistries and molecular sizes. [source] Photopatterning and degradation study of dextran-glycidyl methacrylate hydrogels,POLYMER ENGINEERING & SCIENCE, Issue 2 2010Chi-Wei Lo An approach to synthesizing photopatternable enzymatic degradable dextran hydrogel is presented. The glycidyl methacrylate derivatized dextran (Dex-GMA) was first prepared by reacting dextran with glycidyl methacrylate at 45°C with grafting efficiency of 10%. The degree of substitution (DS) was confirmed by 1H-NMR. Next, Dex-GMA hydrogels were prepared by crosslinking in the presence of a crosslinker: N,N,- methylene-bisacrylamide (NMBA), and a photoinitiator: 2,2,-dimethoxy-2-phenyl acetophenone (DMPA) in dimethyl sulfoxide (DMSO) solution. Further, the Dex-GMA hydrogels were photopatterned using liquid-phase photopolymerization (LP3) technique. The structure size ranged from 5 mm to 300 ,m and three different shapes of structures- - ,round, square, and star- - ,were demonstrated. The patterned Dex-GMA hydrogel structures not only exhibited mechanical robustness but also biodegradability. The dextranase-catalyzed degradation of Dex-GMA hydrogels with different DS was investigated at 37°C. The morphology of the degraded Dex-GMA hydrogels determined by SEM revealed the degree of enzymatic degradation due to dextranase. The Dex-GMA hydrogel was fully degraded by dextranase with concentration of 2 U/ml in 5 days. The Dex-GMA hydrogel also showed the ability to be readily integrated with microfluidics. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [source] | ||||||||||