We dedicate this paper to the memory of Prof. Ulrich Gösele (MPI-Halle), whose support and input were crucial to our work.

We have investigated PLLA crystallization in lamellae-forming PS-b-PLLA confined to straight cylindrical nanopores under weak confinement (nanopore diameter D/equilibrium PS-b-PLLA period L0 ≥ 4.8). Molten PS-b-PLLA predominantly forms concentric lamellae along the nanopores, but intertwined helices occur even for D/L0 ≈ 7.3. Quenching PS-b-PLLA melts below TG(PS) results in PLLA cold crystallization strictly confined by the vitrified PS domains. Above TG(PS), PLLA crystallization is templated by the PS-b-PLLA melt domain structure in the nanopore centers, while adsorption on the nanopore walls stabilizes the outermost cylindrical PS-b-PLLA shell. In between, the nanoscopic PS-b-PLLA melt domain structure apparently ripens to reduce frustrations transmitted from the outermost immobilized PS-b-PLLA layer. The onset of PLLA crystallization catalyzes the ripening while transient ripening states are arrested by advancing PLLA crystallization. Certain helical structure motifs persist PLLA crystallization even if PS is soft. The direction of fastest PLLA crystal growth is preferentially aligned with the nanopore axes to the same degree as for PLLA homopolymer, independent of whether PS is vitreous or soft.

The use of shape-defi ning hard templates containing arrays of cylindrical nanopores, such as self-ordered nanoporous anodic aluminum oxide (AAO), [ 1 , 2 ] is a well-established synthetic approach to one-dimensional (1D) nanostructures. [ 3 ] However, generating specifi c functionalities requires control over mesoscopic structure formation processes occurring in the confi ned geometry of nanorods or nanotube walls, such as crystallization and phase separation. [ 4 ] The self-assembly of block copolymers (BCPs) in nanopores having hard confi ning pore walls has been considered as an attractive access to 1D nanostructures exhibiting mesoscopic fi ne structures as a second hierarchical structure level. Their nanoscopic domain structures could be converted into polymeric scaffolds containing mesoporous structures by post-infi ltration process steps including selective degradation of one of the blocks [ 5 ] or selective swelling of one of the components. [ 6 , 7 ] Since nanotubes can be exploited as nanoscopic containers, pipelines or separation media, it is highly desirable to fabricate tubular nanostructures, the walls of which consist of microphase-separated BCPs. Hence, potential functionalities of nanotubes and of BCPs could be combined. Thus, for example, nanotubes with walls composed of multiple concentric layers having different properties could be accessible in this way. Catalytic systems, micro reactorscharge storage systems, pipelines or sensors consisting of hallow/tubular nanostructures with multilayered walls may show superior properties as compared to device architectures based on corresponding soilid rodlike nanostructures. [ 8 ] BCP nanotubes inside nanoporous hard templates were produced previously by solution-infi ltration of BCPs dissolved in organic solvents. [ 9 , 10 ] In this case, the adsorption kinetics depends on a multitude of parameters including temperature and thermodynamic quality of the solvent. Most importantly, the evaporation of the solvent required for solidifi cation of the BCP is a non-equilibrium process diffi cult to control in a satisfactory manner, which involves additional migration of polymer from the supernatant solution into the pores, separation into solventrich and polymer-rich phases, occurrence of hydro dynamic instabilities and surface reconstruction processes, as well as uncontrolled development of ill-defi ned gradient structures. In contrast, the melt infi ltration of block copolymers has always yielded solid nanorods via a capillary fi lling mechanism. [11][12][13][14] Here we demonstrate that during melt infi ltration of microphase-separated BCPs having a fl uorinated block into AAO hard templates precursor fi lms form, the solidifi cation of which yields exclusively tubular BCP nanostructures. Terminal fl ow of the BCPs is not a prerequisite for precursor fi lm formation if the surface energy of the newly formed BCP/air interface is low enough, thus providing access to tubular BCP nanostructures with walls having mesoscopic fi ne structures such as concentri...

Cobalt iron oxide nanotube arrays with various wall thicknesses were prepared by atomic layer deposition in porous anodic alumina template. Nanotubes uniform in thickness and homogeneous in composition can be obtained with aspect ratios on the order of 50. These nanotubes have a polycrystalline spinel structure. Both the mean grain size and the grain size distribution increase with the tube wall thickness. Correspondingly, their magnetic properties (remanence and coercive field) also have a strong dependence on the thickness for measurements carried out at 300 K. This dependence is attributed to the superparamagnetic behavior of the grains that constitute the nanotube.

Shape-defining hard templates containing arrays of aligned cylindrical nanopores have been exploited as a powerful tool in the synthesis of tubular and solid, rod-like one-dimensional (1D) nanostructures consisting of inorganic and polymeric materials. Gaining control over the mesoscopic fine structure in the 1D nanostructures thus obtained has remained challenging. However, it is easy to conceive that their properties largely depend on internal features characterized by mesoscopic length scales. The self-assembly of block copolymers inside nanopores with hard confining pore walls can be exploited to rationally generate 1D nanostructures with internal self-assembled mesoscopic fine structures. These self-assembled mesoscopic fine structures can be converted to mesopores, into which functional inorganic materials can be deposited. Thus, 1D nanostructures that contain replicas of helical mesopores consisting of functional inorganic materials could be obtained. The complex shapes of the inorganic entities might add additional functionalities to those associated with the bulk inorganic material and with the anisotropy of plain 1D nanostructures. In this way, helical structure motifs can be generated that may exhibit specific optical properties, such as circular dichroism, as shown by simulations