For simple Dorsomorphin anodization, we observe a large ring, whereas the FT of double-anodized alumina shows a less thick and more prominent circle. If a thick ring is typical of a non-spatial organisation and varying inter-pore distances, we verify with the thin ring that a uniform inter-pore distance without any preferred orientation in the organisation is obtained for double-anodized alumina. This confirms the presence of grains with a hexagonal array randomly
orientated. On the FT of the SEM image from the nanoimprinted sample, a hexagonal array of fine dots is seen. This confirms the regularity of the arrays in two directions irrespective of grain size. These samples and the analysis of the SEM images show good versatility and improved control of the array in the case of nanoimprint anodization, making AAO a promising template. In addition,
original structures with a mixed growth of NIL-guided pores and generation of naturally guided pores have been developed. The nanoimprint process is used to pre-texture the aluminium surface with pores in a triangular array of period a. When the anodization voltage is adapted to an array of period , pores will be created in the holes made with the nanoimprint process, and it will force the creation of new pores in the middle of three imprinted ones. Samples Selleckchem Doramapimod with excellent regularity were obtained on surfaces of 4 cm2, as seen in Figure 2e. The shape of these newly created pores, called ‘induced pores’, can be tuned from a triangular to a cylindrical section by changing the acid used and the anodization conditions, whereas
‘imprinted’ ones always present a rounded shape. This technique not only allows to propose original structures but also to get rid of the limitation due to the complexity to produce templates of small period with the standard high-resolution lithography technique, here, electron-beam lithography. This also proves the ability of this technique to eventually restore any missing pore in the initial pattern. A mould of isosceles triangular lattice (230 × 230 × 200 nm3) was also used instead all of the classical equilateral triangle. During oxidation, the isosceles lattice is preserved as depicted in Figure 2f. However, we observe pores enlarging in the direction of the apex, leading to an oval/polygonal pore section. A possible hypothesis to explain this phenomenon is the confinement of the barrier layer in the small direction of the triangle, leading to an impossibility of etching the Al2O3 in this direction . Finally, we show here that the quality of AAO template is widely improved compared to simple or double anodization processes, in terms of homogeneity of the array and pores, in term of size as well as in Selleckchem GDC-973 originality with arrays of oval pore section or double array of cylindrical/triangular pore shape .