Poly(octadecyl acrylate)-Grafted Multiwalled Carbon Nanotube Composites for Wearable Temperature Sensors

Nanocarbon-based disordered, conductive, polymeric nanocomposite materials (DCPNs) are increasingly being adopted in applications across the breadth of materials science. DCPNs characteristically exhibit poor electroconductive properties and irreproducibility/irreversibility in electronic phenomena, due largely to the percolative disordered nature intrinsic to such systems. The authors herein present an alternative approach toward enhancing the thermoresponsivity, repeatability, and reversibility of nanocarbon-based DCPNs in thermometric applications. This is empirically demonstrated using poly(octadecyl acrylate)-grafted-multiwall carbon nanotubes (PODA-g-MWCNTs) synthesized via reversible addition–fragmentation chain-transfer (RAFT) polymerization. Synthesized PODA-g-MWCNTs exhibit repeatable, near-pyrexia sensitized, switch-like electronic responses across subtle glass transitions characterized by an exceptionally large positive temperature coefficient of resistance values of 7496.53% K–1 ± 3950.58% K–1 at 315.1 K (42.0 °C). This corresponds to a sizable transition rate of 17.39 kΩ K–1 ± 0.49 kΩ K–1, and recoverable near room temperature resistance values of 246.17 Ω ± 12.19 Ω at 298.2 K (25.1 °C). Near-human body temperature sensitized PODA-g-MWCNTs assembled in this work are promising candidates for wearable temperature sensors and other thermometric applications.