Improving film characteristics of pyrene derivatized carbon nanotubes by 3-aminopropyltri-ethoxysilane and N,N′-Diisopropylcarbodiimide crosslinker

In this work, we used different pyrenes derivatives with a carboxylic acid group to modify the surface of carbon nanotubes (CNTs). This non-covalent method of functionalization can improve the dispersion of CNTs in organic solvent without damaging the desired properties of CNTs. Thin films of CNTs functionalized with pyrene derivatives were deposited onto the glass substrate, which in prior, was treated by 3-aminopropyltri-ethoxysilane (APTES). N,N'-Diisopropylcarbodiimide (DIC), a cross-linker, facilitates the reaction of carboxylic acid group on CNTs with the amino group of APTES. We found that the introduction of DIC resulted in increased robustness of CNTs thin films on the glass substrate. Increase of interfacial adhesion can be attributed to the covalent bond formed during this process. We studied the effect of concentration of APTES and DIC on film adherence by subjecting them to waterjet. Our results show that the CNTs thin films were robust and smooth. The morphology analysis by Scanning Electron Microscopy and Atomic Force Microscopy techniques reveal that the surface functionalized CNTs thin films on glass substrates were smooth and the roughness was about 21.3 nm for the APTES-treated sample. We obtained relatively smooth CNTs thin films which possess high interfacial adhesion with the glass substrate due to covalent bond formed between amino group and carboxylic acid group.