InterNano Nanomanufacturing Repository
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Importance of dynamic hydrogen bonds and reorientation barriers in proton transport
No full textThe dynamic nature of hydrogen bonds in phenolic polymers, where the hydrogen bond donor/acceptor reorientation can occur in a single site, presents lower barriers for proton transport
Aligned nanowires and nanodots by directed block copolymer assembly
No full textThe directed self-assembly of block copolymers (BCPs) is a promising route to generate highly ordered arrays of sub-10 nm features. Ultradense arrays of a monolayer of spherical microdomains or cylindrical microdomains oriented parallel to the surface have been produced where the lateral ordering is guided by surface patterning and the lattice defined by the patterning can be commensurate or incommensurate with the natural period of the BCP. Commensurability between the two can be used to elegantly manipulate the lateral ordering and orientation of the BCP microdomains so as to form well-aligned arrays of 1D nanowires or 2D addressable nanodots. No modification of the substrate surface, aside from the patterning, was used, making the influence of lattice mismatch and pattern amplification on the size, shape and pitch of the BCP microdomains more transparent. A skew angle between incommensurate lattices, defining a stretching or compression of the BCP chains to compensate for the lattice mismatch, is presented
Hydrogen Bond Assisted Assembly of Well-Ordered Polyhedral Oligomeric Silsesquioxane-Block Copolymer Composites
No full textWell-ordered block copolymer nanocomposites with d-spacings as small as 15 nm and additive loadings greater than 70 mass % were formed upon blending functionalized polyhedral oligomeric silsesquioxanes (POSS) additives into disordered block copolymers containing poly(ethylene oxide) (PEO) as one of the blocks. The POSS additives were functionalized with maleamic acid or aminophenyl groups as ligands to enable selective hydrogen bonding with the PEO chains. The selective interaction of the additives with the PEO chains caused microphase separation of the block copolymer leading to formation of well-ordered morphologies as evidenced by small-angle X-ray scattering. Further addition of the additive induced transitions between cylindrical and spherical morphologies. While both ligands induced order, the maleamic acid ligand enabled higher levels of incorporation of POSS cages into the PEO phases of the composite. Differential scanning calorimetry and wide-angle X-ray diffraction were performed to confirm compatibility and good mixing of the additives within the PEO phase. The maleamic ligands can be cross-linked by a thermal treatment. The cross-linking was used to stabilize the structure of the composites prior to calcination at high temperatures, which resulted in the formation of mesoporous silica. Transmission electron microscopy showed that the cylindrical and spherical morphologies of the parent composites were maintained in the mesoporous silica
Sequential Electrodeposition of Platinum-Ruthenium at Boron-Doped Diamond Electrodes for Methanol Oxidation
No full textTunable metallic-like conductivity in microbial nanowire networks
No full textElectronic nanostructures made from natural amino acids are attractive because of their relatively low cost, facile processing and absence of toxicity(1-3). However, most materials derived from natural amino acids are electronically insulating(1-6). Here, we report metallic-like conductivity in films of the bacterium Geobacter sulfurreducens(7) and also in pilin nanofilaments (known as microbial nanowires(8,9)) extracted from these bacteria. These materials have electronic conductivities of similar to 5 mS cm(-1), which are comparable to those of synthetic metallic nanostructures(2). They can also conduct over distances on the centimetre scale, which is thousands of times the size of a bacterium. Moreover, the conductivity of the biofilm can be tuned by regulating gene expression, and also by varying the gate voltage in a transistor configuration. The conductivity of the nanofilaments has a temperature dependence similar to that of a disordered metal, and the conductivity could be increased by processing
