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Polyaramides are materials that have been used in the manufacture of bullet proof vests and sports equipment for many years. Their excellent materials properties are largely due to their rigid rod-like geometry and their ability to form weak (hydrogen bond) interactions between the rigid polymer chains. We want to exploit the rigid rod-like characteristics of shorter and more soluble versions of the above-mentioned polymers as molecular scaffolds for the construction of nanoscopic architectures. In one sub-project we use these materials to build helices from linear and angled building blocks. A combination of covalent and non-covalent interactions allows us to assemble linear segments containing a kink into long helical polymers. One aim is to explore whether it is possible to make tubular helices with a large inner void. These could be used for the construction of porous membranes, low density materials, as nano-reactors or as molecular carriers. In another sub-project, we want to use similar rigid rod-like building blocks as molecular rulers. By attaching anchor sites at well-defined distances we could attach nanoparticles, chromophores or other compounds at precisely defined distances from each other. This can allow us to study the distance dependend interaction of such compounds.

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Last update: 21.02.2013

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Number	Title	Start	Funding scheme

The aim of the project is to synthesise shape persistent, highly functional and sequence-controlled oligoaramides. These oligomers are built from aromatic amino acid building blocks and represent themselves oligomeric amino acids. Polymerisation of these oligomeric amino acids will lead to high molecular weight polymers in which the sequence-controlled oligomer is continuously repeated. As a consequence, different types of functional nanostructures can be obtained. Two in particular will be the focus of this research proposal: 1) 1D-templates for nanoparticles, i.e. linear one-dimensional templates with recurring binding sites for inorganic nanoparticles at well-defined distances and 2) giant helices in which helix diameter and inside/outside polarity of the helix can be designed.1D-templates for nanoparticlesShort oligoaramides will be prepared that carry binding sites at well-defined positions within the oligomer. Due to the rigid rod-like and shape persistent nature of the resulting polymer all binding sites will have exactly the same distance from their next intramolecular neighbours. These molecular rulers can be used to bind inorganic nanoparticles, chromophores or other functional molecular structures. These templated one-dimensional assemblies are particularly interesting to study the distance dependent photon, electron or spin-interactions between the bound particles.Giant helicesThis research project describes the synthesis of large helical polymers via the polycondensation of complex shape persistent nanoscopic objects. The size and shape of these oligomers are directly controlled by the position of linear and bent units within the oligomer, i.e. the monomer sequence. The shape persistent oligomers can be seen as double stranded "ladder"-type structures in which the covalent bonds represent one strand and the non-covalent hydrogen bonds the other. This double stranded nature of the oligomer ensures that the geometrically desired conformer is energetically highly favoured. By variation of the substituents and monomer sequence, we expect to be able to control the polarity and functionality on the inside and outside of the helix independently. The helix diameter is controlled by the length of the oligomeric monomers and the angle of the "turn-inducing" monomer. Racemic mixtures of giant helical polymers can be prepared in this manner. The hollow interior of the helices or tubes can potentially serve as a host for guests of various sizes. Control of the helix size and its interior and exterior substitution pattern, might offer the possibility to selectively encapsulate guests. Such synthetic organic tubes are interesting materials which can find potential applications as nanoscopic reactors, for analyte enrichment or in size and affinity separation applications.