Polymer crystallization enabled carbon nanotube functionalization: morphology, structure and applications /

by Li, Lingyu.; Li, Christopher Yuren.; College of, Drexel University.

Polymer Crystallization Enabled Carbon Nanotube Functionalization: Morphology, Structure and Applications Lingyu Li Advisor: Christopher Li, Ph.D. Carbon Nanotubes (CNT) have attracted tremendous attention and numerous potential applications have been proposed. In this thesis study, a unique means to modify CNT surface with polymer crystals via controlled polymer crystallization method has been developed. CNTs were wrapped in polymer single crystal lamellae in a periodic manner, resulting in nano hybrid shish-kebab (NHSK) structures. The periodicity of the polymer lamellae can be varied from 20 - 150 nm. The kebabs are ~5 nm thick (along CNT direction) with a lateral size of ~ 20 nm to micrometers, which can be readily controlled by varying crystallization conditions. PE, Nylon 66 and PE-b-SBR were successfully decorated on single-walled carbon nanotubes (SWNT), multi-walled carbon nanotubes (MWNT), as well as vapor grown carbon nanofibers (CNF). The formation mechanism was attributed to “size dependent soft epitaxy”. Efforts were focused on PE/SWNT system to understand the growth mechanism and the effect of experimental parameters on the periodicity. It was found that weight ratio of SWNT and PE (defined as R) played an important role and periodicity increases with increasing R. This was attributed to a reduced polymer concentration at the crystal growth front. Since NHSK formation conditions depend upon CNT structures, it further provides a unique opportunity for CNT separation. Applications of using NHSK in CNT dispersions, separation and nanocomposites have also been successfully developed. This unique means is different from all the xviii reported methods and it opens a gateway to achieving periodically functionalized CNT for a variety of applications ranging from nanocomposites, sensors, fuel cells etc. 1