(260b) Porous Hollow Carbon Nanotube Composite Cages

Polyelectrolyte hollow spheres have been extensively investigated due to their potential applications as filler materials, microreactors, artificial cells and drug delivery vehicles.1 Among the currently available fabrication methods, the one adopting the layer-by-layer (LBL) coating technique is of particular interest due to the benefits of allowing multiple layers of different functional materials (e.g., functional polyelectrolytes) to be coated onto a sacrificial template particle. Subsequent template removal results in hollow spheres whose functionality and cage size can be controlled by the coated material and diameter of the template particle, respectively. However, for extremely large target species such as enzymes and proteins, the size of the pores present within the shell have to be made comparable to the size of those molecules, deteriorating the mechanical strength of the hollow sphere.The simultaneous achievement of a robust hollow architecture and improved large molecule permeability still remains a challenge. This work reports the fabrication of composite hollow spheres, consisting of carbon nanotubes (CNTs), polyelectrolyte molecules and inorganic materials (e.g., silica and titania), which are both mechanically robust and permeable to large species such as nanoparticles. It is anticipated that the incorporated CNTs will provide the composite spheres with mechanical strength and unique properties (e.g., electrical conductivity), while the polyelectrolyte will provide flexible functionality and tunable surface charges. Meanwhile, the inorganic component may provide protection, additional mechanical strength and other functionalities This work provides novel platforms for microreactors, artificial cells, controlled delivery and other applications. Further work is under way to synthesize CNT-based hollow spheres with controlled pore sizes, tunable functionalities, responsive properties through tuning the coating process and conditions, tuning functionalities and charges on CNTs, introducing functional components, and other strategies.