Torsten Pietsch

Functional hybrid materials

Nanofabrication via self-assembly of hybrid materials into well-defined architectures is essential for the next generation of miniaturized devices. This paper describes our groups achievements towards the development of multifunctional nanostructures via self-assembly of hybrid systems based on the block copolymer PS-b-P4VP and inorganic nanoparticles (NPs) into 0D, 1D, 2D and complex 3D periodic nanostructures. The morphologies of these architectures are adjusted to gain functions via structural control at different dimensions.

Nano- and micro-sized honeycomb patterns through hierarchical self-assembly of metal-loaded diblock copolymer vesicles

Herein we present a novel approach for fabricating metallic micro- and nano-structures in thin films viaspin-coating solutions of diblock copolymer vesicles. A simple concept was developed, which is based on the metallization and self-assembly diblock copolymers. Firstly, vesicles incorporating the inorganic components are generated in solution by adjusting the solvent ratio in water–toluene mixtures. Subsequently, thin films are deposited onto a solid substrate viaspin-coating. As a result micro- and nano-sized honeycomb structures are obtained; the pore diameter is dependent on the size and size distribution of the vesicles. Hence, control over the pattern dimensions and the degree of order can be achieved by tuning the vesicle diameter prior to film deposition. Finally, the block copolymer is extracted by means of oxygen plasma etching, leaving behind inorganic Au-nanostructures that mimic the original film morphology. The surface properties of these honeycomb patterns, in terms of hydrophobicity, can be adjusted by controlling the film thickness and the characteristic dimension of the pattern.

Water-soluble CdSe nanoparticles stabilised by dense-shell glycodendrimers

A simple and rapid method has been developed to prepare water-soluble CdSe nanoparticles at room temperature, with average particle diameters around 2 nm, stabilised by maltose-modified 2nd–5th generation poly(propylene imine) (PPI) dendrimers.

Hybrid Nanoalloy: Nanofibers Fabricated by Self‐Assembling Dendrimers Mediate In Situ CdSe Quantum Dots and Their Metallization with Discrete Gold Nanoparticles

Controlling the assembly of individual nanoparticles into welldefi ned nanostructures by self-assembled hybrid materials is a powerful technique to fabricate novel functional nanomaterials. [ 1 ] This type of nanofabrication facilitates the formation of different anisotropic nanostructures. [ 2 ] Among these types of nanostructures, 1D nanostructured hybrid organic–inorganic materials [ 3 ] have attracted signifi cant attention, not only because of their unique physical properties, but also because they can be used as building blocks to achieve a high degree of integral functionality useful for the next generation of miniaturized devices. Herein we report on a simple approach to fabricate metallized high density semiconducting hybrid nanofi bers based on self-assembled dendrimer templated CdSe nanoparticles in situ at room temperature. The dendrimer@CdSe hybrid nanofi bers are prepared by a wet chemical method in aqueous medium and have been used as a scaffold to deposit discrete metallic nanoparticles. Dendrimers are globular macromolecules composed of a core, dendrons, and surface groups. [ 4 ] Dendrimers possess many merits such as well-defi ned molecular structures and monodispersity in molecular weight. [ 5 ] Poly(propyleneimine) (PPI) is a common type of dendrimer consisting of tertiary amine groups in the dendritic scaffold and peripheral primary amine groups (Figure 1-SI, Supporting Information). [ 6 ] The unique dendritic architecture of PPI provides a simple tool to modulate intermolecular interactions by dissimilarity in the protonation state between the dendritic scaffold (core) and peripheral shell. [ 7a ]

Nanoporous Thin Films and Binary Nanoparticle Superlattices Created by Directed Self-Assembly of Block Copolymer Hybrid Materials

The design and development of well-defined, functional nanostructures via self-assembly is one of the key objectives in current nanotechnology. Block copolymer-based hybrid materials are attractive candidates for the fabrication of multifunctional nanostructures, which provide the building blocks for more complex nanoarchitectures and nanodevices. However, one of the major challenges lies in controlling the structure formation in these hybrid materials by guiding the self-assembly of the block copolymer. Here, hierarchical nanoporous structures are fabricated via guided multistep self-assembly of diblock copolymer micellar solutions onto hydrophilic solid substrates. The core of polystyrene-block-poly[4-vinylpyridine] micelles serves as a nanoreactor for the preparation of size-controlled gold nanoparticles. Deposition of thin films of the micellar solution in combination with a nonselective cosolvent (THF), on hydrophilic surfaces leads to the formation of hierarchical nanoporous structures. The micellar films exhibit two different pore diameters and a total pore density of more than 10(10) holes per cm2. Control over the pore diameter is achieved by adapting the molecular weight of the polystyrene-block-poly[4-vinylpyridine] diblock copolymer. Moreover, the porous morphology is used as a template for the fabrication of bimetallic nanostructured thin films. The PS-b-P4VP template is subsequently removed by oxygen plasma etching, leaving behind binary nanoparticle structures that mimic the original thin film morphology.

Cation‐Induced Unidirectional Self‐Assembly of Amino‐Terminated Poly(propylene imine) Dendrimers

Nanofabrication via directed self-assembly of hybrid mate-rials into well-defi ned nanostructures is a powerful tool to produce functional building blocks, which possess unique optical, magnetic, and electronic properties that are essential for the next generation of nanodevices. In particular, hybrid materials based on dendrimers in combination with inorganic components resemble an ideal functional system for nano-structuring via hierarchical self-assembly. Recently, it has been shown that dendrimers can act as unimolecular micelles for the controlled synthesis and stabilization of inorganic nano-particles.