Strategy to synthesise nano-engineered polymer nanocomposite with a mechanically strong interface: a highly flexible ammonia gas sensor

Abstract

The work reported herein describes a facile strategy for synthesize of a highly flexible and free standing novel polymethyl methacrylate/nanographite platelets nanocomposite (P-NC) film through click chemistry. The unique concept involves the formation of P-NCs which not only imparts the strong covalent interaction between the azide functionalized polymethyl methacrylate (Az-f-PMMA) and alkyne functionalized nanographite platelets (Alk-f-NGPs) at the interface through triazole linkages but also enhances the exfoliation of NGPs within the polymer matrix. Thus, the synergy between the polymer and the NGPs through the high density of interfaces results in remarkable electrical, mechanical and sensing properties. The structure and micromorphology of the prepared P-NCs were confirmed by FTIR, NMR, XPS, UV spectroscopy, Raman spectroscopy, XRD, TGA, SEM, TEM and AFM techniques. A maximum indentation elastic modulus (E) of 4.1 GPa and hardness (H) of 0.23 GPa were obtained for P-NC with an ultralow loading of 0.1% NGPs, as compared to 3.3 GPa and 0.17 GPa, respectively, for pure PMMA. The flexible, robust P-NC films demonstrated excellent sensing properties towards ammonia vapor with fast response and recovery, both at room temperature (response = ∼2 s, recovery = ∼32 s) as well as at 0 °C (response = ∼1 s, recovery = ∼13 s). The work reported opens up new opportunities for the development of robust and portable P-NC sensors which can detect ammonia vapor in refrigeration plants where leakage should be indicated both at low temperature near the valves, as well as room temperature in the surrounding atmosphere, having flexibility to be fabricated in any shape as per the positioning of the sensor in the refrigeration plant.