Large-scale carbon nanotube synthesis

Carbon nanotubes (CNTs) are a form of crystalline carbon with extraordinary chemical, physical, electrical and mechanical properties, making them potentially valuable in a broad range of applications. These properties have resulted in an unprecedented level of interest in the development of techniques to manufacture CNTs, and consequently a raft of competing patents have been issued, with universities and commercial entities alike looking to obtain patent protection for their inventions. In this paper we review relevant aspects of international patent law, summarize CNT definitions and discuss patent irregularities, and discuss the implications of the widening gap between nanotechnology practice and the underlying patent law. This is followed by a review of the chemical vapour deposition technique of CNT synthesis, in particular using a fluidised bed, identified as the most promising method to date for the large-scale, low cost production of CNTs. We further examine the carbon nanotube patent space, focusing primarily on patents for CNTs produced via CVD and FBCVD techniques. This patent space is both convoluted and uncertain, and it appears likely that some form of litigation will ensue in future to ultimately determine intellectual property ownership in various regions. We also discuss the likely effect of this 'patent thicket' on the commercialisation of large-scale CNT synthesis processes.