MSE PhD proposal- Amir A. Bakhtiary Davijani

Date: Friday, December 4th 2015 

Time: 1:00 PM

Location: MRDC 4404

Title: Effect of poly(methyl methacrylate) wrapping on the structure and properties of CNT films, and polymer/CNT films and fibers 

Committee:
Prof. Satish Kumar, Advisor, MSE
Prof. Karl Jacob, MSE
Prof. Hamid Garmestani, MSe
Prof. Donggang Yao, MSE
Prof. Seung Woo Lee, ME

Abstract
Carbon nanotubes (CNTs) exhibit high electrical and thermal conductivity and good mechanical properties, making them suitable fillers for composites. Their effectiveness as a filler is affected by their state of aggregation. Various solvents, surfactants, and processing techniques have been studied to improve CNT dispersion in polymers. However, to-date there is no ideal solution for achieving good CNT dispersion. In this study, a novel process has been developed that prevents CNT aggregation. Ordered helical wrapping of poly (methyl methacrylate) (PMMA) has been achieved on single wall carbon nanotubes (SWNTs). PMMA wrapped SWNT dispersions in dimethyl formamide (DMF) are found to be stable for over three months at room temperature. Ordered PMMA wrapping has been confirmed by X-ray diffraction, and the wrapping behavior has also been verified using molecular modeling. PMMA only wraps on SWNTs and not on larger diameter nanotubes, such as few wall and multi wall carbon nanotubes. PMMA wrapped SWNT dispersions have also been characterized using UV-vis and Raman spectroscopies.
This study focuses on investigating the properties of the CNT buckypapers, as well as polymer/CNT films and fibers using PMMA wrapped SWNTs as well as unwrapped SWNTs. SWNT buckypapers, typically have a surface area of about 600 m 2 /g. However, using this PMMA wrapping approach, SWNT buckypapers with surface area as high as 950 m 2 /g have been processed. These buckypapers exhibit significantly improved energy storage performance when used as electrodes in electrochemical supercapacitor. In another part of this study PMMA/SWNT films are being processed with PMMA wrapped as well as unwrapped SWNTs. Structure and properties of these films will be studied and the effect of PMMA wrapping on the performance of these nano composite films will be delineated. Stress transfer differences from the matrix to the nanotubes will be studied in the two nanocomposites using Raman spectroscopy, and the effect of PMMA wrapping on the stress transfer will be characterized. In the final part of this study, polyacrylonitrile (PAN) /SWNT fibers will be processed with PMMA wrapped and unwrapped SWNT. These fibers will be stabilized and carbonized. Structure and properties of the precursor fiber, and the resulting carbon fibers will be studied. The role of PMMA wrapping on SWNT will be studied in PAN/SWNT fibers and their carbon fibers.