A new and easy method for making Ni and Cu microtubules and their regularly assembled structures

Ni and Cu microtubules of several centimeters in length can be easily prepared using a new method herewith by the pyrolysis of composite fibers consisting of a poly(ethylene terephthalate) (PET) core fiber and an electroless-plated metal skin layer. Through the use of this approach, the diameter, wall-thickness, and length of metal microtubules can be conveniently controlled. Various analytical methods, including scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, and electron paramagnetic resonance, were used to characterize the resultant metal microtubules. The results indicated that the Ni microtubules essentially consist of single crystalline fcc-Ni, with the normal of the {110} planes being parallel to the direction of the tube axis, whereas the resultant Cu microtubules are polycrystalline. The respective conductivities for the resultant Ni and Cu microtubules were 1.22 x 10(5) (+/- 20%) S/cm and >1.58 x 10(5) (+/- 25%) S/cm, quite similar to those of pure metals. Most interestingly, this method also provides a feasible approach for the preparation of two- or three-dimensional well-organized metal microtubular assemblies from suitable woven fabrics or structures.