Effect of Surface Functionalization of Single-Walled Carbon Nanotubes (SWCNT) on Mechanical Properties of Ultra-Low Weight Percent SWCNT Reinforced PDMS Composite Thin Films

This study investigates the effect of single-walled carbon nanotube's (SWCNT) surface functionalization on the dispersion and reinforcing effect in polydimethylsiloxane (PDMS) thin films. At ultra-low weight percentage loadings (0.05 wt%, 0.5 wt%, and 1 wt%), carboxylic acid functionalized SWCNT (COOH-SWCNT) and silylated SWCNT (Sily-SWCNT) are compared as fillers on PDMS matrix. Fourier Transform Infrared (FTIR) analysis is used for chemical characterization of the samples. The optical transparency of the samples is measured using Ultraviolet-Visible (UV-Vis) spectrophotometer to quantify the improvement, which is an outcome of the better dispersion of functionalized SWCNT in PDMS. Delamination analysis (DL) is used to quantify the mechanical bond strength and time taken for delamination in composite thin films. Dynamic mechanical analysis (DMA) is used to estimate the stress-strain relationship in the samples under a tensile force ramp. Nanoindentation analysis (NI) is used to estimate the hardness (H) and elastic modulus (E) of the samples for a perpendicular indentation force. From the combined chemical, optical, and mechanical characterizations, the effect of the chemical bond strengths in the sample due to the surface functionalization of SWCNT is correlated with the mechanical bond strengths imparted to the composite films.