Quantitative\nConductive Atomic Force Microscopy on Single-Walled Carbon Nanotube-Based\nPolymer Composites

Abstract

Conductive\natomic force microscopy (C-AFM) is a valuable technique for correlating\nthe electrical properties of a material with its topographic features\nand for identifying and characterizing conductive pathways in polymer\ncomposites. However, aspects such as compatibility between tip material\nand sample, contact force and area between the tip and the sample,\ntip degradation and environmental conditions render quantifying the\nresults quite challenging. This study aims at finding the suitable\nconditions for C-AFM to generate reliable, reproducible, and quantitative\ncurrent maps that can be used to calculate the resistance in each\npoint of a single-walled carbon nanotube (SWCNT) network, nonimpregnated\nas well as impregnated with a polymer. The results obtained emphasize\nthe technique’s limitation at the macroscale as the resistance\nof these highly conductive samples cannot be distinguished from the\ntip–sample contact resistance. Quantitative C-AFM measurements\non thin composite sections of 150–350 nm enable the separation\nof sample and tip–sample contact resistance, but also indicate\nthat these sections are not representative for the overall SWCNT network.\nNevertheless, the technique was successfully used to characterize\nthe local electrical properties of the composite material, such as\nsample homogeneity and resistance range of individual SWCNT clusters,\nat the nano- and microscale.