Molecular self-assembly scales up from nanometers to millimeters

A joint effort of the Aalto University of Helsinki, the Politecnico di Milano, and VTT Technical Research Centre of Finland has now demonstrated that it is possible to align molecular self-assemblies from nanometers to millimeters without the intervention of external stimuli.

Molecular self-assembly is a concept derived from Nature that leads to the spontaneous organization of molecules into more complex and functional supramolecular structures. The recipe is “encoded” in the chemical structure of the self-assembling molecules. Molecular self-assembly has been exploited for “templating” functional devices, molecular wires, memory elements, etc. However, it has typically required additional processing steps to achieve extended alignment of the structures.

The new finding showed that by engineering recognition elements between polymers and fluorinated small molecules, it has been possible to drive their spontaneous self-assembly from nanometers to millimeters, thanks to the judicious use of noncovalent interactions. After the processing, fluoromolecules can optionally be removed upon thermal treatment.

This concept opens up new avenues in large area nanoconstruction, for example in templating nanowires, which is currently under investigation.

Nature Communications – Halogen-bonded mesogens direct polymer self-assemblies up to millimetre length scale

Aligning polymeric nanostructures up to macroscale in facile ways remains a challenge in materials science and technology. Here we show polymeric self-assemblies where nanoscale organization guides the macroscopic alignment up to millimetre scale. The concept is shown by halogen bonding mesogenic 1-iodoperfluoroalkanes to a star-shaped ethyleneglycol-based polymer, having chloride end-groups. The mesogens segregate and stack parallel into aligned domains. This leads to layers at ~10 nm periodicity. Combination of directionality of halogen bonding, mesogen parallel stacking and minimization of interfacial curvature translates into an overall alignment in bulk and films up to millimetre scale. Upon heating, novel supramolecular halogen-bonded polymeric liquid crystallinity is also shown. As many polymers present sites capable of receiving halogen bonding, we suggest generic potential of this strategy for aligning polymer self-assemblies.

6 pages of supplemental information

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