Carbon Nanotubes and Graphene

During 2010-11, One focus of Subproject 4 was studying graphitic parallel layers as formed on SiC surface when SiC is decomposed at high temperatures. We have determined that oxygen interacts with graphitic network initiates the formation of nano-caps. The surface deformations on the graphitic networks by oxygen lead to the growth of CNTs. The mechanism is able to explain various structural features of CNTs/SiC (b) growth and mechanism of graphene. A new technology of graphene growth on oxidized SiC is being developed, and (c) we have started to develop nano-porous (TiO2-polymer composites) and polymeric conducting materials for efficient electron interface transfers. In summary, progress has been made in finding new methods of synthesis of metal- free carbon nano-tube production, expand the knowledge on their properties and modifications and finally we have succeeded in growing graphene on oxidized SiC.

During the 2011 the research interests centered on (a) growth mechanism of metal-free carbon nano-structures. An atomic scale mechanism of metal-free CNT growth is proposed. Graphitic parallel layers are formed on SiC surface when SiC is decomposed at high temperatures. Oxygen interacts with graphitic network initiates the formation of nano-caps. The surface deformations on the graphitic networks by oxygen lead to the growth of CNTs. The mechanism is able to explain various structural features of CNTs/SiC (b) growth and mechanism of graphene. A new technology of graphene growth on oxidized SiC was developed, and (c) we started to develop nano-porous (TiO2-polymer composites) and polymeric conducting materials for efficient electron interface transfers. Some of the major facilities used in this activity were transferred when one of our researchers ( a Co-PI) left the center for another job. We will continue this activity with the completion of the work of a graduate student in 2012.

Polymers: Synthesis of Multipurpose Membrances

Another emphasis of project 4 was the synthesis and characterization of multipurpose membranes for fuel cells and reverse osmosis. This activity was directed by our new chemistry faculty, Dr. Arnett. The focus of this research has been to synthesize and characterize multipurpose membranes for proton exchange membrane fuel cells (PEMFCs) and reverse osmosis (RO). The primary focus of the PEMFC work has been to 1) synthesize disulfonated poly(arylene ether sulfone tetrachlorocyclotriphosphazene) (PAES-TCCP) hybrid copolymers as proton exchange membranes (PEM) for fuel cells and 2) to prepare disulfonated bisphenol A based PAES (BisA-XX) random copolymers to be used in blends with HCCP that display similar mechanical properties but have Tg’s that are at least 30 ºC lower than the biphenol based series with comparable levels of disulfonation. In the RO area, polyamide-polyetheramide (PAPEA) copolymers have been prepared by interfacial polymerization. The Project started September, 2010.

This research focuses on preparing proton-exchange membranes for fuel cells based on PAES-TCCP-XX hybrid copolymers with varying degrees of sulfonation. Polymer membranes created to date are insufficiently proton conductive to be useful for fuel cells. This research will combine the unique properties of HCCP monomer with disulfonated poly(arylene ether sulfone) (PAES) copolymer to prepare novel hybrid polymers with increased hydrophilicity, high proton conductivity, thermal stability, and mechanical properties.