['In', 'contrast', 'with', 'polymers', ',', 'which', 'are', 'typically', 'synthesized', 'in', 'the', 'liquid', 'phase', ',', 'SWNTs', 'are', 'produced', 'through', 'a', 'variety', 'of', 'synthesis', 'techniques', 'that', 'typically', 'involve', 'the', 'reaction', 'of', 'a', 'gaseous', 'carbon', 'feedstock', 'to', 'form', 'the', 'nanotubes', 'on', 'catalyst', 'particles', '.']