Carbon nanotubes encapsulated in wormlike hollow silica shells

The synthesis of carbon nanotubes (CNT) encapsulated inside hollow silica capsules that has lots of application in cosmetics, encapsulation, confined-catalysis, controlled drug release and development of artificial cells was described. The CNT encapsulated inside hollow silica capsule is fabricated by coating the CNTs with silica and then selectively etching away the silicon from the inside out. The process comprises of successive acid- and base-catalyzed silica condensation, and firstly, nanotubes are functionalized with positively charged polyelectrolyte poly(allyamine hydrochloride) for stable dispersion of CNT. CNTs are dispersed in water by means of the polymerwrapping technique. During process, the hydrolysis and condensation of 3-aminopropyltrimethoxysilane and tetraethoxysilane is done in acidic medium and the pH of solution is rapidly increased for silane condensation. TEM and UV/Vis spectroscopy analysis indicates dissolution of silica shell from inside.