The present work serves as a scalable basis upon which to expand the usage of MWCNT/polymeric nanocomposites into high-conductivity applications.

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)-graf ted-multiwall carbon nanotubes (PODA-g-MWCNTs) synthesized via reversible addition−fragmentation chain-transfer (RAFT) polymerization. Synthesized PODA-g-MWCNTs exhibit repeatable, nearpyrexia 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.

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Development and optimization of multiphase nanoscale systems and functional nanoarchitectures require a meticulous physicochemical understanding of interfacial regions and their interactions. Disordered multiphase systems like polymer nanocomposites often exhibit intricate and convoluted interfacial regions across interphases. [1-4] Resolving such nanocomposite interphases with sub-micrometer resolution and chemical exactitude is of substantial importance towards a complete quantitative understanding of nanoscale systems. [5] Vibrational spectroscopies afford the most chemical specificity, but are notably limited in spatial resolution. Conversely, electron microspectroscopies provide the highest spatial resolution but lack a high degree of chemical specificity, particularly for organic species. Electron and other high resolution microspectroscopies like scanning transmission X-ray microscopynear edge X-ray absorption fine structure spectroscopy (STXM-NEXAFS) typically require the sample to be characterized under vacuum, which can appreciably affect particle morphology and composition at the particle vacuum interface. Advancements in ubiquitous techniques like Fourier transform-infrared (FTIR) spectroscopy have culminated with the advent of the discrete-frequency quantum cascade laser (QCL), enabling single-frequency infrared (IR) imaging and faster data acquisition. [6] Notwithstanding advancements, such far-field IR vibrational microspectroscopies lack depth-resolving capabilities and are intrinsically restricted in spatial resolution by the wavelength-dependent diffraction limit of the probing IR light, which is typically between 5 and 12 µm across fingerprint regions and dependent on the particular objective lens used. [7] Efforts to circumvent such diffraction limited resolution have led to recent progress in optical-photothermal infrared (O-PTIR) microspectroscopy techniques, where selective absorbance of mid-IR excitation laser light is detected using a visible light probe laser via a photothermally induced thermal lensing effect. [8-18] In such all-optical schemes, the detectable signal is the modulated probe laser power ΔP probe , which is linearly proportional to