Novel ZnO nanostructures grown on carbon nanotubes by thermal evaporation

We report on the formation of ZnO/carbon nanotubes heterostructures achieved by means of a thermal evaporation method. Scanning electron microscopy revealed that the main building block of the observed morphologies was the nanorod whose self-assembling resulted in various structures such as polypods and nano-hedgehogs, depending on various factors as well as the location of the ZnO-CNT junction. X-ray diffraction and photoluminescence spectroscopy were used to study the structure and optical properties of obtained nanostructures. Semi-empirical molecular orbital calculations gave evidence for the nature of the binding between ZnO and CNTs.     

GISAXS study of Si nanoclusters in SiO/SiO2 layers

We present a study on amorphous SiO/SiO₂ superlattice using grazing-incidence small-angle X-ray scattering (GISAXS). Such nanostructured material might be of great interest for photovoltaic conversion and optoelectronics. Amorphous SiO/SiO₂ superlattices were prepared by magnetron sputtering of thin SiO and SiO₂ films (20 layers each) on Si (1 0 0) substrate. Rotation of the Si substrate during evaporation ensures homogeneity of the films over the whole substrate. After the evaporation, the samples were annealed at 1100 °C for 1 h in vacuum. The analysis of the 2-D GISAXS pattern has shown that Si nanocrystals are formed in the remaining SiO₂ films in the annealed samples. From the 2-D GISAXS pattern, their shape, size and inter-particle distance are determined.     

Multiwalled Carbon Nanotubes Catalytically Grown from Amorphous Silica Films Deposited by Combustion CVD

Homogeneous mixtures containing iron oxide and amorphous SiO₂ were obtained through the co-deposition of these oxides via combustion chemical vapor deposition technique (CCVD). This technique allows the deposition of thin films with low-cost precursors and equipments. After deposition, the deposited samples were submitted to a heat treatment in an atmosphere composed of natural gas and H₂ at 1000°C, in order to promote the growth of carbon nanotubes. Multiwalled carbon nanotubes, with diameters smaller than 15 nm, were obtained.     

Enzyme-catalyzed preparation of supramolecular structured hydrogel of polypseudorotaxanes derived from the self-assembly of α-CDs with 3-arm p-hydroxyphenylpropionate terminated PEG

A kind of novel 3-D cross-linked supramolecular structured hydrogels has been fabricated via enzymatic oxidative coupling of polypseudorotaxanes (PPRs) derived from the self-assembly of α-cyclodextrins (α-CDs) with 3-arm p-hydroxyphenylpropionate terminated PEG (3-HPPP) as a macromer by using horseradish peroxidase (HRP)/H₂O₂ catalytic system. The enzymatic cross-linking of the macomer or PPRs made with a smaller amount of α-CDs was found to be much faster than that by ordinary chemical pathways, showing the promise to be used as the surgical adhesive and sealant which are needed to rapidly function in vivo. The gelation time was highly extended and the gel content was considerably decreased by increasing the α-CDs to macromer feeding molar ratio. Thereby these hydrogels exhibited a decreasing trend in dynamical mechanical properties with increasing the amount of α-CDs in regard to the blank hydrogel made without α-CD addition.     

Recent developments in nanofabrication using ion projection lithography

Ion projection lithography (IPL) is an emerging technology and a major candidate for the next-generation lithography (NGL) designed to complement and supplement current optical lithographic techniques for future chip manufacturing. In this Review, the recent developments of IPL technology are examined with an emphasis on its ability to fabricate a wide variety of nanostructures for the semiconductor industry. Following an introduction of the uniqueness and strength of the technology, the basics of ion-source development and ion-target interactions with and without chemical enhancement are presented. The developments in equipment systems, masks, and resists are subsequently studied. The resolution of printed nanostructures and the corresponding throughput of the current system are assessed for NGL. Finally, concluding remarks are presented to summarize the strengths and weaknesses of the current technology and to suggest the scope for future improvement.     

Effects of a hindered phenol compound on the dynamic mechanical properties of chlorinated polyethylene,acrylic rubber,and their blend

The dynamic mechanical properties of binary hybrids of chlorinated polyethylene (CPE) and acrylic rubber (ACM) with 3,9‐bis{1,1‐dimethyl‐2[β‐(3‐tert‐butyl‐4‐ hydroxy‐5‐methylphenyl)propionyloxy]ethyl}‐2,4,8,10‐tetraoxaspiro[5,5]‐undecane (AO‐80) and their ternary hybrids were investigated. The addition of AO‐80 was successful in tailoring the damping profile. The ACM/AO‐80 hybrids show only one relaxation, which is larger than that of pure ACM, whereas for the CPE/AO‐80 hybrids, one novel relaxation appears above the glass‐transition temperature of CPE. In the case of CPE/AO‐80/ACM, a supramolecular network was formed by a crosslink due to hydrogen bonding. The replacement of a part of CPE by ACM increased the value in the middle of two peaks. The AO‐80 molecule, which is a bifunctional hydrogen‐bonding acceptor, was found to act as a compatibilizer. In addition, in such ternary hybrids, the tan δ value in the middle of the two peaks was found to be proportional to the slope of the E′ curve at an identical temperature. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2468–2473, 2001