Raman Response of Carbon Nanotube/PVA Fibers under Strain

We study the strain-induced shift of the D* Raman band of single-wall carbon nanotubes in polyvinyl alcohol−nanotube composite fibers. If embedded in structural components, such strain-sensitive fibers may be considered for potential applications as strain or stress sensors. Due to improved interfacial adhesion, stronger shifts of the D* Raman band are observed when carboxylic functional groups are present at the nanotube surface. This indicates that nanotube carboxylation would yield better efficacy for future sensing applications. However, we also observe that the improvements of interfacial adhesion do not lead to substantially better mechanical properties of the fibers. This effect is discussed by considering possible degradation of nanotubes during surface functionalization.