Mechanically neutral and facile monitoring of thermoset matrices with ultrathin and highly porous carbon nanotube films

We examine how the physical features of single-walled carbon nanotube (SWCNT) thin films can affect monitoring thermoset polymers during their manufacturing and application. Film thickness (23, 37 and 53 nm), electrode materials and configuration, and embedding within or surface application on a polymer were all investigated. During manufacturing monitoring, thicker films provided higher sensitivity than thinner ones (ΔR/R0 = 111 % (53 nm) vs. 74 % (23 nm)). Electrode material and configuration showed that sputtered gold contacts allow higher sensitivity and reliability compared with conductive silver adhesive, and that parallel electrode placement provides more distinct and discreet stage measurements compared to diagonal. The opposite trend was noted for mechanical loading, where thinner films provide a higher piezoresistive response and embedded films outperform surface applied sensors (gauge factors between 23-86 and 4–10, respectively). All thin films accurately measured curing stages as well as mechanical changes, and are shown to be self-adjusting when the force increases during mechanical loading. We show that manufacturing monitoring should rely on uniformly deposited electrodes and thicker films for identification of polymerization stages, whereas embedding thinner films in the matrix is recommended for highly sensitive deformation monitoring. This work outlines how simple, overlooked parameters can easily be varied to optimize the dual-stage monitoring performance of CNT-based sensors and helps to identify what parameters should be chosen for specific applications. [Display omitted] •SWCNT films cause no mechanical loss and provide fast monitoring of thermosets.•Sensitivity was thickness and electrode-geometry dependent.•Thicker films are preferable for detecting thermoset curing stages.•Thinner films are preferable for embedded application and structural monitoring.•Embedded SWCNT films outperforms MWCNTs alternatives for thermoset monitoring.