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4th Phase Technologies manufactures robust and durable, ultrathin densified carbon nanotube (DCN) sheets from raw pristine CNT sheets.  Raw pristine CNT sheets are synthesized via the floating catalyst chemical vapor deposition technique. In this technique, CNTs are synthesized in situ in a high-temperature furnace, gently pulled out of the furnace and loosely laid together and pressed to generate the final sheet form. This technique is capable of generating raw pristine CNT sheets of various sizes, shapes and thickness.  


However, raw pristine CNT sheets have various amounts of amorphous carbon, large irregular pores and generally are not durable for most applications. Thin raw pristine CNT sheets easily fracture and the loss of CNTs from raw pristine CNT sheets is a concern as CNTs in raw pristine sheets readily adhere to other surfaces on contact. Even though individual CNTs have been shown to have great physical strength and chemical stability, raw pristine CNT sheets need further treatment to impart practical utility.  


Conventional techniques use polymers as binding agents to hold CNTs together in an attempt to make stronger sheets. However, there are intrinsic drawbacks with the composite approach: i.e., 1) polymer materials are not as chemically stable as CNTs; 2) it requires uniform dispersion of CNTs in order to make uniform composite and uniform dispersion of CNTs requires physical means and CNT surface chemical functionalization, which create more structural defects in CNTs, making it poorly reproducible. 

A proprietary purification and densification process overcomes the above challenges. The resulting DCN sheets unlock the constraints of polymer membranes or polymer-based composite membranes.

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