Working Group Chemical Physics

Synthesis and Separation of Carbon Nanotubes (F. Hennrich)

Our research is focused on synthesis (Chemical Vapor Decomposition (CVD), Pulse Laser Vaporization) and sorting (by length, diameter, (n, m)) of Single Wall Carbon Nanotubes (SWNTs). SWNTs exhibit outstanding physical and chemical properties, making them excellent candidate in a wide range of applications including electronics, photonic, sensors and energy conversion. Up to now, SWNT production processes are not selective in producing only one (n, m)-species. Their applications are deeply correlated to this issue as device performances are strongly affected by SWNTs purity. Therefore post-processing approach including sorting of SWNTs is compulsory for their integration as active component in devices. For sorting SWNTs e. g. polymer wrapping is a non-destructive selective method using non-covalent and specific interactions that allows an efficient and scalable process for sorting SWNTs (n, m)-species.

Nano-Carbon Materials (S. Malik)

• - Chemical Vapour Deposition (CVD) of Vertically Aligned Carbon Nanotubes (VANTAs)
• - Graphene Synthesis by Intercalation of Highly Ordered Pyrolytic Graphite (HOPG)
• - Branched-Multi-Walled Carbon Nanotubes (b-MWCNTs)

Carbon nanotubes (CNTs) have atomically smooth surfaces and tend not to form covalent bonds with composite matrix materials. Thus, it is the magnitude of the CNT/fiber interfacial strength which limits the amount of nanomechanical interlocking when using conventional CNTs to improve the structural behavior of composite materials through reinforcement.

Two main issues are widely recognized as being critical for the development of mechanically efficient nanocomposites: (1) adequate dispersion of the nano-reinforcement filler within the matrix, and (2) strong interfacial bonding between the reinforcement element and matrix. This arises from poor dispersion of the CNTs which in turn leads to aggregation in certain areas of the matrix. However, a network of branched CNTs would significantly reduce this network resistance (Figure 1). This would provide major benefits to the existing commercial application of CNT reinforced composites in Electrostatic Discharge Materials (ESD) as well as potential usage in Supercapacitors, Solar Cells and Li-Ion batteries.